The authors would like to acknowledge the following NIH awards/subawards for the support of this research: R01HL106790, R01HL106790-S1, R01HL106786, R01AI089323, R21AI091457, R21RR026006, P20RR020159, C06RR017563, 8T32OD011124-08, and P51OD011104.

1. Calibrate Mesodissection Instrument with 2iD Imaging Software
The 2iD imaging software will be referred to as either the software or the program for the remainder of this article. This step is needed to correctly track the image as well as align multiple slide frames.
<ol>
	<li>Turn on instrument and computer.</li>
	<li>Open software and select &#8220;calibrate instrument&#8221;.</li>
	<li>Calibrate stage travel by using the joystick. Move stage to upper left position. Press &#8220;set&#8221; under step 1 in program.</li>
	<li>Move stage to lower right position. Press &#8220;set&#8221; under step 2 in program.</li>
	<li>Calibrate aspiration by first pressing &#8220;Z-button&#8221; to raise head assembly. Press &#8220;aspirate pulse&#8221; button and &#8220;dissection&#8221; button on the joystick until plunger control rod reaches top position. Press &#8220;set&#8221; under step 3 of program.</li>
	<li>Press &#8220;aspirate reset&#8221; button. Once the plunger stops at the bottom position press &#8220;set&#8221; in step 4.</li>
	<li>Click on the &#8220;scale tab&#8221;.</li>
	<li>Place calibration ruler on blank side.</li>
	<li>Focus microscope if needed.</li>
	<li>Draw line between the two scale bars using mouse.</li>
	<li>Enter distance in box labeled step 2. Press &#8220;compute&#8221; button.</li>
	<li>Click on &#8220;crosshair&#8221; tab. Turn motor speed to 1.</li>
	<li>Insert xScisor into head assembly. Lower head assembly into z-axis ready position by pressing &#8220;z-axis&#8221; button. NOTE: The head assembly is the large structure on the top the dissection instrument. The xScisor will be referred to as a consumable mill bit for the remainder of this article.</li>
	<li>Click &#8220;dissection engage&#8221; button on joystick. NOTE: This button is located on the top of the joystick.</li>
	<li>Define center of rotation visually. To do this, move center of crosshair over center of rotation using defined parameter in step 1 of program. Use the up and down arrows in the &#8220;x&#8221; and &#8220;y-axis&#8221; bars to adjust the pixels to align crosshair. Click the &#8220;done&#8221; tab.</li>
	<li>Click on &#8220;home&#8221; icon. NOTE: This is represented by a house image located in the upper right hand corner.</li>
</ol>
2. Create Reference Image
<ol>
	<li>Place H&#38;E slide on stage. Place opaque cover on top of slide. Drive the instrument by moving the joystick to the desired area of the H&#38;E slide. Save the image generated. NOTE: Either the &#8220;capture reference&#8221; tab or &#8220;dissect&#8221; tab can be used to complete this step.</li>
</ol>
3. Align Tissue for Dissection
<ol>
	<li>Click the &#8220;dissect tissue&#8221; option on the home screen.</li>
	<li>Fill out the &#8220;operator,&#8221; &#8220;dissection accession number,&#8221; &#8220;reference accession number,&#8221; &#8220;xScisor barcode number,&#8221; &#8220;dissection fluid lot number,&#8221; &#8220;xScisor size&#8221; and &#8220;description&#8221; in the &#8220;setup&#8221; tab.</li>
	<li>Click on the &#8220;find tissue&#8221; tab.</li>
	<li>Import previously saved reference image.</li>
	<li>Place an unstained FFPE slide of 5 micron thickness on the stage. Move stage to the same area as the one depicted in the reference image. Click on &#8220;insert image&#8221; tab.</li>
	<li>Click on &#8220;align&#8221; tab. Use the mouse and associated arrows to align the reference image to the unstained image.</li>
</ol>
4. Annotate Slide
<ol>
	<li>Click on the &#8220;annotate&#8221; tab.</li>
	<li>Use the mouse to draw a circle around the desired area of the slide that will be microdissected.</li>
</ol>
5. Load Consumable Mill Bit
<ol>
	<li>Fill consumable mill bit with desired buffer, here PKD buffer, by pulling the plunger up and down in a fluid motion several times. Make sure to exclude air bubbles.</li>
	<li>Raise Z-axis by pressing &#8220;Z-axis button&#8221;.</li>
	<li>Load consumable mill bit into machine. Do this by sliding the consumable mill bit into the top of the machine so that the white line on the instrument lines up with the black line on the consumable mill bit. Press &#8220;aspiration reset&#8221; button to allow plunger to be lowered into the correct position. NOTE: It should be easy to slide the consumable mill bit. If it is not, make sure the notches are correctly aligned.</li>
	<li>Lower Z-axis by again pressing &#8220;Z-axis&#8221; button.</li>
</ol>
6. Dissect Tissue (Figure 4)
<ol>
	<li>Open &#8220;dissect&#8221; tab.</li>
	<li>Turn motor and aspiration speeds to 1.</li>
	<li>Check &#8220;show tracking&#8221; box. Note: This allows the user to visualize the dissected area during the dissection process.</li>
	<li>Once ready to dissect, continue to hold &#8220;engage&#8221; button as well as &#8220;aspirate&#8221; button while moving joystick in a counterclockwise direction to dissect tissue.</li>
	<li>Continue to dissect in a counterclockwise direction until the aspirate is &#8220;full&#8221; tab turns red.</li>
</ol>
7. Empty and Remove Consumable Mill Bit
<ol>
	<li>Place a 0.5 &#181;l microfuge tube under the tip of the consumable mill bit.</li>
	<li>Press &#8220;aspiration&#8221; control rod quickly to eject sample into microfuge tube.</li>
	<li>Press with increased force to eject used consumable mill bit.</li>
	<li>Rinse tissue fragment by pulling plunger back. Push plunger forward to express remaining sample into consumable mill bit. The tissue fragment will now be contained within the microfuge tube.</li>
</ol>
8. Lyse Sample with Proteinase K Digestion Followed by Heat Treatment
<ol>
	<li>Add 70 &#181;l TE pH 8.5 containing 5 &#181;g of proteinase K to recovered tissue sample.</li>
	<li>Place sample into programmable heater-shaker.</li>
	<li>Complete digestion using programmable heater-shaker at the following setting: 60 &#730;C for 30 min at 1,500 rpm; 82 &#730;C for 15 min at 1,500 rpm; and 25 &#730;C for 1 min at 450 rpm. The sample is now ready for downstream applications.</li>
</ol>

<ol>
	<li>Fend, F., Raffeld, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser+capture+microdissection+in+pathology.">Laser capture microdissection in pathology.</a> J Clin Pathol. 53 (9), 666-672 (2000).</li><li>Esposito, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Complementary+techniques:+laser+capture+microdissection--increasing+specificity+of+gene+expression+profiling+of+cancer+specimens.">Complementary techniques: laser capture microdissection--increasing specificity of gene expression profiling of cancer specimens.</a> Adv Exp Med Biol. 593, 54-65 (2007).</li><li>Adey, N., Bosh, D., Emery, D., Birch, L., Parry, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesodissection+of+Paraffin+Embedded+Slide+Mounted+Tissue+Sections.">Mesodissection of Paraffin Embedded Slide Mounted Tissue Sections.</a> Journal of Molecular Diagnostics. 14 (6), (2012).</li><li>Fleischmann, R. D., Alland, D., Eisen, J. A., Carpenter, L., White, O., Peterson, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Whole-genome+comparison+of+Mycobacterium+tuberculosis+clinical+and+laboratory+strains.">Whole-genome comparison of Mycobacterium tuberculosis clinical and laboratory strains.</a> J Bacteriol. 184 (19), 5479-5490 (2002).</li><li>Russell, D. G., Barry 3rd, C. E., Flynn, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tuberculosis:+what+we+don't+know+can,+and+does,+hurt+us.">Tuberculosis: what we don't know can, and does, hurt us.</a> Science. 328 (5980), 852-856 (2010).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesodissection+of+fibrous+tissue.">Mesodissection of fibrous tissue.</a> AvanSciBio. , (2013).</li><li>Paige, C., Bishai, W. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Penitentiary+or+penthouse+condo:+the+tuberculous+granuloma+from+the+microbe's+point+of+view.">Penitentiary or penthouse condo: the tuberculous granuloma from the microbe's point of view.</a> Cell Microbiol. 12 (3), 301-309 (2010).</li><li>Mehra, S., Alvarez, X., Didier, P. J., Doyle, L. A., Blanchard, J. L., Lackner, A. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Granuloma+correlates+of+protection+against+tuberculosis+and+mechanisms+of+immune+modulation+by+Mycobacterium+tuberculosis.">Granuloma correlates of protection against tuberculosis and mechanisms of immune modulation by Mycobacterium tuberculosis.</a> J Infect Dis. 207 (7), 1115-1127 (2013).</li><li>Kaushal, D., Schroeder, B. G., Tyagi, S., Yoshimatsu, T., Scott, C., Ko, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reduced+immunopathology+and+mortality+despite+tissue+persistence+in+a+Mycobacterium+tuberculosis+mutant+lacking+alternative+sigma+factor,+SigH.">Reduced immunopathology and mortality despite tissue persistence in a Mycobacterium tuberculosis mutant lacking alternative sigma factor, SigH.</a> Proc Natl Acad Sci U S A. (12), 8330-8335 (2002).</li><li>Mehra, S., Kaushal, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+genomics+reveals+extended+roles+of+the+Mycobacterium+tuberculosis+stress+response+factor+sigmaH.">Functional genomics reveals extended roles of the Mycobacterium tuberculosis stress response factor sigmaH.</a> J Bacteriol. 191 (12), 3965-3980 (2009).</li><li>Rohde, K. H., Veiga, D. F., Caldwell, S., Balazsi, G., Russell, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Linking+the+transcriptional+profiles+and+the+physiological+states+of+Mycobacterium+tuberculosis+during+an+extended+intracellular+infection.">Linking the transcriptional profiles and the physiological states of Mycobacterium tuberculosis during an extended intracellular infection.</a> PLoS Pathog. 8 (6), (2012).</li><li>Fontan, P. A., Voskuil, M. I., Gomez, M., Tan, D., Pardini, M., Manganelli, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Mycobacterium+tuberculosis+sigma+factor+sigmaB+is+required+for+full+response+to+cell+envelope+stress+and+hypoxia+in+vitro,+but+it+is+dispensable+for+in+vivo+growth.">The Mycobacterium tuberculosis sigma factor sigmaB is required for full response to cell envelope stress and hypoxia in vitro, but it is dispensable for in vivo growth.</a> J Bacteriol. 191 (18), 5628-5633 (2009).</li><li>Rustad, T. R., Harrell, M. I., Liao, R., Sherman, D. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+enduring+hypoxic+response+of+Mycobacterium+tuberculosis.">The enduring hypoxic response of Mycobacterium tuberculosis.</a> PLoS One. 3 (1), (2008).</li></ol>

The authors disclose that there are no competing financial interests.

Mesodissection is a technique that can be applied to RNA extraction from pathologic lesion slides caused by a vast array of pathogens. It is a necessity that the user tracks the image and aligns the image correctly. To accomplish this, the instrument must be calibrated following the directions on the imaging software. When dissecting, if the slide and area of interest being dissected do not align, the user must recalibrate the instrument. Another critical step in the dissection process is to load the consumable mill bit ...

The corresponding author was changed for the article, <a href="http://www.jove.com/video/51693">A Novel Microdissection Approach to Recovering Mycobacterium tuberculosis Specific Transcripts from Formalin Fixed Paraffin Embedded Lung Granulomas</a>. The corresponding author was changed from:
Teresa A. Hudock
to:
Deepak Kaushal

The corresponding author was changed for the article, <a href="http://www.jove.com/video/51693">A Novel Microdissection Approach to Recovering Mycobacterium tuberculosis Specific Transcripts from Formalin Fixed Paraffin Embedded Lung Granulomas</a>.

Erratum: A Novel Microdissection Approach to Recovering Mycobacterium tuberculosis Specific Transcripts from Formalin Fixed Paraffin Embedded Lung Granulomas

Samples have traditionally been manually microdissected from either whole tissue or slides using a needle and scalpel. This necessitates a clear separation between the tissue section of interest and surrounding tissues sections2. With the current advancements in molecular profiling technology, there has been an increasing need to assess tissue at the cellular level. Due to the limitations of manual microdissection, techniques including LCM were established to allow greater isolation precision. This technique allows the researcher to isolate specific cell populations from various cell and slide types, which can then be used for downstream assays such as gene expression profiling. Although very effective for downstream assays, LCM is not without limitations. First, LCM is an expensive and time consuming process. Additionally, due to the unstable nature of RNA, it is often challenging to obtain high quality RNA from LCM samples2. Due to the disadvantages of LCM, new advances in microdissection technology are still needed to make it more accessible to a greater number of researchers in an affordable and time sensitive manner.
One such advancement in microdissection technology now available is a technique known as mesodissection. In this technique a machine is used to mill the annotated tissue section of interest and aspirates it into a consumable mill bit3. Next, this sample can be aspirated into a collection tube and used for downstream applications. The advantages of this system are that it is significantly less expensive and time sensitive. In our experience, the system allows the dissection of a lung granuloma tissue section in ten minutes. On the other hand, traditional LCM would likely require hours to complete the process. The system allows the operator to load a reference slide to use as a comparison as well as tool for annotation. Additionally a report is generated outlining the area of the slide that was dissected. There are two main disadvantages to mesodissection. Although effective at extracting multiple cells, it is challenging to isolate a single cell. In addition, the precision of the image generated is not as clear as if using other imaging microscopes.
Tuberculosis (TB) is a major infectious disease killer of humanity worldwide and results from infection with Mtb. In a majority of individuals exposed to aerosols of Mtb, the infection is latently limited. In at least 10 million people annually, it results in active TB disease4. During latent infection, Mtb is contained within pathological lung lesions known as granulomas. Hence it has been argued that the outcome of Mtb infection is decided at the level of the granuloma5.
Here we demonstrate how mesodissection can be used to microdissect granulomas caused by Mtb. The slides used are from FFPE lung tissue from infected rhesus macaques. For the purpose of this demonstration, we will dissect granulomas in their entirety. We also demonstrate that RNA can be extracted from the recovered tissue. This technique can be applied to tissue samples from various other specimens and then used for a variety of downstream assays.

<table border="0" cellpadding="0" cellspacing="0" width="675">
	<tbody>
		<tr height="20">
			<td height="20" style="height:20px;width:260px;">MeSectr</td>
			<td style="width:113px;">AvanSci Bio</td>
			<td style="width:108px;"></td>
			<td style="width:195px;">Mesodissector</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">400 nm xScisors</td>
			<td>AvanSci Bio</td>
			<td></td>
			<td>Other sizes available</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">THOR</td>
			<td>AvanSci Bio</td>
			<td></td>
			<td>Programmable Heater-Shaker</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">NanoDrop2000</td>
			<td>ThermoScientific</td>
			<td>ND-2000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">RNeasy FFPE extraction kit&#160;</td>
			<td>Qiagen</td>
			<td align="right" style="width:108px;">73504</td>
			<td style="width:195px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ovation RNA-Seq FFPE System&#160;</td>
			<td>Nugen</td>
			<td align="right">7150</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">QIAquick PCR Purification Kit&#160;</td>
			<td>Qiagen</td>
			<td align="right" style="width:108px;">28104</td>
			<td style="width:195px;"></td>
		</tr>
	</tbody>
</table>

a novel microdissection approach to recovering mycobacterium tuberculosis specific transcripts from formalin fixed paraffin embedded lung granulomas

Microdissection has been used for the examination of tissues at DNA, RNA, and protein levels for over a decade. Laser capture microscopy (LCM) is the most common microdissection technique used today. In this technique, a laser is used to focally melt a thermoplastic membrane that overlies a dehydrated tissue section1. The tissue section composite is then lifted and separated from the membrane. Although this technique can be used successfully for tissue examination, it is time consuming and expensive. Furthermore, the successful completion of procedures using this technique requires the use of a laser, thus limiting its use. A new more affordable and practical microdissection approach called mesodissection is a possible solution to the pitfalls of LCM. This technique employs the MESO-1/MeSectr system to mill the desired tissue from a slide mounted tissue sample while concurrently dispensing and aspirating fluid to recover the desired tissue sample into a consumable mill bit. Before the dissection process begins, the user aligns the formalin fixed paraffin embedded (FFPE) slide with a hematoxylin and eosin stained (H&#38;E) reference slide. Thereafter, the operator annotates the desired dissection area and proceeds to dissect the appropriate segment. The program generates an archived image of the dissection. The main advantage of mesodissection is the short duration needed to dissect a slide, taking an average of ten minutes from set up to sample generation in this experiment. Additionally, the system is significantly more cost effective and user friendly. A slight disadvantage is that it is not as precise as laser capture microscopy. In this article we demonstrate how mesodissection can be used to extract RNA from slides from FFPE granulomas caused by Mycobacterium tuberculosis (Mtb).

The aforementioned protocol shows how to use a new mesodissection technique to extract RNA from FFPE tissue slides. This protocol&#8217;s efficacy is shown through FFPE slides of lung granulomas from NHP infected with Mtb in various infective stages. Figures 1-3&#160;are images of the instrument. Figure 4 depicts how the dissection process occurs and the resulting image generated by the software. Table 1 shows the results of RNA extraction with a granuloma from ...

Watch this Scientific Journal Video about A Novel Microdissection Approach to Recovering Mycobacterium tuberculosis Specific Transcripts from Formalin Fixed Paraffin Embedded Lung Granulomas at JoVE.c

A Novel Microdissection Approach to Recovering Mycobacterium tuberculosis Specific Transcripts from Formalin Fixed Paraffin Embedded Lung Granulomas

Microdissection has been extensively employed for the examination of DNA, RNA, and protein within tissue. Laser capture microscopy (LCM) is the most commonly used method, but a new milling technique, mesodissection, is recently available. We demonstrate RNA extraction from mesodissected formalin fixed paraffin embedded tissue slides of Mycobacterium tuberculosis granulomas.

A Novel Microdissection Approach to Recovering Mycobacterium tuberculosis Specific Transcripts from Formalin Fixed Paraffin Embedded Lung Granulomas

Microdissection has been used for the examination of tissues at DNA, RNA, and protein levels for over a decade. Laser capture microscopy (LCM) is the most ...

a-novel-microdissection-approach-to-recovering-mycobacterium

Research

JoVE Journal

Immunology and Infection

7.9K Views.  Tulane National Primate Research Center. Microdissection has been extensively employed for the examination of DNA, RNA, and protein within tissue. Laser capture microscopy (LCM) is the most commonly used method, but a new milling technique, mesodissection, is recently available. We demonstrate RNA extraction from mesodissected formalin fixed paraffin embedded tissue slides of Mycobacterium tuberculosis granulomas.

Video: A Novel Microdissection Approach to Recovering Mycobacterium tuberculosis Specific Transcripts from Formalin Fixed Paraffin Embedded Lung Granulomas

Sample Preparation of Mycobacterium tuberculosis Extracts for Nuclear Magnetic Resonance Metabolomic Studies

Mycobacterium tuberculosis is a major cause of mortality in human beings on a global scale. The emergence of both multi- (MDR) and extensively-(XDR) drug-resistant strains threatens to derail current disease control efforts. Thus, there is an urgent need to develop drugs and vaccines that are more effective than those currently available. The genome of M. tuberculosis has been known for more than 10 years, yet there are important gaps in our knowledge of gene function and essentiality. Many studies have since used gene expression analysis at both the transcriptomic and proteomic levels to determine the effects of drugs, oxidants, and growth conditions on the global patterns of gene expression. Ultimately, the final response of these changes is reflected in the metabolic composition of the bacterium including a few thousand small molecular weight chemicals. Comparing the metabolic profiles of wild type and mutant strains, either untreated or treated with a particular drug, can effectively allow target identification and may lead to the development of novel inhibitors with anti-tubercular activity. Likewise, the effects of two or more conditions on the metabolome can also be assessed. Nuclear magnetic resonance (NMR) is a powerful technology that is used to identify and quantify metabolic intermediates. In this protocol, procedures for the preparation of M. tuberculosis cell extracts for NMR metabolomic analysis are described. Cell cultures are grown under appropriate conditions and required Biosafety Level 3 containment,1 harvested, and subjected to mechanical lysis while maintaining cold temperatures to maximize preservation of metabolites. Cell lysates are recovered, filtered sterilized, and stored at ultra-low temperatures. Aliquots from these cell extracts are plated on Middlebrook 7H9 agar for colony-forming units to verify absence of viable cells. Upon two months of incubation at 37 &deg;C, if no viable colonies are observed, samples are removed from the containment facility for downstream processing. Extracts are lyophilized, resuspended in deuterated buffer and injected in the NMR instrument, capturing spectroscopic data that is then subjected to statistical analysis. The procedures described can be applied for both one-dimensional (1D) 1H NMR and two-dimensional (2D) 1H-13C NMR analyses. This methodology provides more reliable small molecular weight metabolite identification and more reliable and sensitive quantitative analyses of cell extract metabolic compositions than chromatographic methods. Variations of the procedure described following the cell lysis step can also be adapted for parallel proteomic analysis.

Sample Preparation of Mycobacterium tuberculosis Extracts for Nuclear Magnetic Resonance Metabolomic Studies

The metabolomic profile of Mycobacterium tuberculosis is determined after growth in broth cultures. Conditions can be varied to test the effects of nutritional supplements, oxidants, and anti-tuberculosis agents on the metabolic profile of this microorganism. Procedure for extract preparation is applicable for both 1D 1H and 2D 1H-13C NMR analyses.

Mycobacterium tuberculosis is a major cause of mortality in human beings on a global scale. The emergence of both multi- (MDR) and extensively-(XDR) ...

Growth of Mycobacterium tuberculosis Biofilms

Mycobacterium tuberculosis, the etiologic agent of human tuberculosis, has an extraordinary ability to survive against environmental stresses including antibiotics. Although stress tolerance of M. tuberculosis is one of the likely contributors to the 6-month long chemotherapy of tuberculosis 1, the molecular mechanisms underlying this characteristic phenotype of the pathogen remain unclear. Many microbial species have evolved to survive in stressful environments by self-assembling in highly organized, surface attached, and matrix encapsulated structures called biofilms 2-4. Growth in communities appears to be a preferred survival strategy of microbes, and is achieved through genetic components that regulate surface attachment, intercellular communications, and synthesis of extracellular polymeric substances (EPS) 5,6. The tolerance to environmental stress is likely facilitated by EPS, and perhaps by the physiological adaptation of individual bacilli to heterogeneous microenvironments within the complex architecture of biofilms 7.
In a series of recent papers we established that M. tuberculosis and Mycobacterium smegmatis have a strong propensity to grow in organized multicellular structures, called biofilms, which can tolerate more than 50 times the minimal inhibitory concentrations of the anti-tuberculosis drugs isoniazid and rifampicin 8-10. M. tuberculosis, however, intriguingly requires specific conditions to form mature biofilms, in particular 9:1 ratio of headspace: media as well as limited exchange of air with the atmosphere 9. Requirements of specialized environmental conditions could possibly be linked to the fact that M. tuberculosis is an obligate human pathogen and thus has adapted to tissue environments. In this publication we demonstrate methods for culturing M. tuberculosis biofilms in a bottle and a 12-well plate format, which is convenient for bacteriological as well as genetic studies. We have described the protocol for an attenuated strain of M. tuberculosis, mc27000, with deletion in the two loci, panCD and RD1, that are critical for in vivo growth of the pathogen 9. This strain can be safely used in a BSL-2 containment for understanding the basic biology of the tuberculosis pathogen thus avoiding the requirement of an expensive BSL-3 facility. The method can be extended, with appropriate modification in media, to grow biofilm of other culturable mycobacterial species.
Overall, a uniform protocol of culturing mycobacterial biofilms will help the investigators interested in studying the basic resilient characteristics of mycobacteria. In addition, a clear and concise method of growing mycobacterial biofilms will also help the clinical and pharmaceutical investigators to test the efficacy of a potential drug.

Growth of Mycobacterium tuberculosis Biofilms

Mycobacterium tuberculosis forms drug tolerant biofilms when cultured in certain conditions. Here we describe methods for culturing M. tuberculosis biofilms and determining the frequency of drug tolerant persisters. These protocols will be useful for further studies into the mechanisms of drug tolerance in M. tuberculosis.

Mycobacterium tuberculosis, the etiologic agent of human tuberculosis, has an extraordinary ability to survive against environmental stresses including ...

An Experimental Model to Study Tuberculosis-Malaria Coinfection upon Natural Transmission of Mycobacterium tuberculosis and Plasmodium berghei

Coinfections naturally occur due to the geographic overlap of distinct types of pathogenic organisms. Concurrent infections most likely modulate the respective immune response to each single pathogen and may thereby affect pathogenesis and disease outcome. Coinfected patients may also respond differentially to anti-infective interventions. Coinfection between tuberculosis as caused by mycobacteria and the malaria parasite Plasmodium, both of which are coendemic in many parts of sub-Saharan Africa, has not been studied in detail. In order to approach the challenging but scientifically and clinically highly relevant question how malaria-tuberculosis coinfection modulate host immunity and the course of each disease, we established an experimental mouse model that allows us to dissect the elicited immune responses to both pathogens in the coinfected host. Of note, in order to most precisely mimic naturally acquired human infections, we perform experimental infections of mice with both pathogens by their natural routes of infection, i.e. aerosol and mosquito bite, respectively.

An Experimental Model to Study Tuberculosis-Malaria Coinfection upon Natural Transmission of Mycobacterium tuberculosis and Plasmodium berghei

Tuberculosis and malaria are two of the most prevalent infections in humans and major causes of morbidity and mortality in impoverished populations in the tropics. We established an experimental model system to study outcome of malaria-tuberculosis coinfection in mice after challenge with both pathogens via their natural route of infection.

Coinfections naturally occur due to the geographic overlap of distinct types of pathogenic organisms. Concurrent infections most likely modulate the ...

Demonstrating a Multi-drug Resistant Mycobacterium tuberculosis Amplification Microarray

Simplifying microarray workflow is a necessary first step for creating MDR-TB microarray-based diagnostics that can be routinely used in lower-resource environments. An amplification microarray combines asymmetric PCR amplification, target size selection, target labeling, and microarray hybridization within a single solution and into a single microfluidic chamber. A batch processing method is demonstrated with a 9-plex asymmetric master mix and low-density gel element microarray for genotyping multi-drug resistant Mycobacterium tuberculosis (MDR-TB). The protocol described here can be completed in 6 hr and provide correct genotyping with at least 1,000 cell equivalents of genomic DNA. Incorporating on-chip wash steps is feasible, which will result in an entirely closed amplicon method and system. The extent of multiplexing with an amplification microarray is ultimately constrained by the number of primer pairs that can be combined into a single master mix and still achieve desired sensitivity and specificity performance metrics, rather than the number of probes that are immobilized on the array. Likewise, the total analysis time can be shortened or lengthened depending on the specific intended use, research question, and desired limits of detection. Nevertheless, the general approach significantly streamlines microarray workflow for the end user by reducing the number of manually intensive and time-consuming processing steps, and provides a simplified biochemical and microfluidic path for translating microarray-based diagnostics into routine clinical practice.

Demonstrating a Multi-drug Resistant Mycobacterium tuberculosis Amplification Microarray

An amplification microarray combines asymmetric PCR amplification and microarray hybridization into a single chamber, which significantly streamlines microarray workflow for the end user. Simplifying microarray workflow is a necessary first step for creating microarray-based diagnostics that can be routinely used in lower-resource environments.

Simplifying microarray workflow is a necessary first step for creating MDR-TB microarray-based diagnostics that can be routinely used in lower-resource ...

In Situ Detection of Bacteria within Paraffin-embedded Tissues Using a Digoxin-labeled DNA Probe Targeting 16S rRNA

The presence of bacteria within the pocket epithelium and underlying connective tissue in gingival biopsies from patients with periodontitis has been reported using various methods, including electron microscopy, immunohistochemistry or immunofluorescence using bacteria-specific antibodies, and fluorescent in situ hybridization (FISH) using a fluorescence-labeled oligonucleotide probe. Nevertheless, these methods are not widely used due to technical limitation or difficulties. Here a method to localize bacteria within paraffin-embedded tissues using DIG-labeled DNA probes has been introduced. The paraffin-embedded tissues are the most common form of biopsy tissues available from pathology banks. Bacteria can be detected either in a species-specific or universal manner. Bacterial signals are detected as either discrete forms (coccus, rod, fusiform, and hairy form) of bacteria or dispersed forms. The technique allows other histological information to be obtained: the epithelia, connective tissue, inflammatory infiltrates, and blood vessels are well distinguished. This method can be used to study the role of bacteria in various diseases, such as periodontitis, cancers, and inflammatory immune diseases.

In Situ Detection of Bacteria within Paraffin-embedded Tissues Using a Digoxin-labeled DNA Probe Targeting 16S rRNA

Here a method to localize bacteria within paraffin-embedded tissues using DIG-labeled 16S rRNA-targeting DNA probes has been described. This protocol can be applied to study the role of bacteria in various diseases such as periodontitis, cancers, and inflammatory immune diseases.

The presence of bacteria within the pocket epithelium and underlying connective tissue in gingival biopsies from patients with periodontitis has been ...

A 3D Human Lung Tissue Model for Functional Studies on Mycobacterium tuberculosis Infection

Tuberculosis (TB) still holds a major threat to the health of people worldwide, and there is a need for cost-efficient but reliable models to help us understand the disease mechanisms and advance the discoveries of new treatment options. In vitro cell cultures of monolayers or co-cultures lack the three-dimensional (3D) environment and tissue responses. Herein, we describe an innovative in vitro model of a human lung tissue, which holds promise to be an effective tool for studying the complex events that occur during infection with Mycobacterium tuberculosis (M. tuberculosis). The 3D tissue model consists of tissue-specific epithelial cells and fibroblasts, which are cultured in a matrix of collagen on top of a porous membrane. Upon air exposure, the epithelial cells stratify and secrete mucus at the apical side. By introducing human primary macrophages infected with M. tuberculosis to the tissue model, we have shown that immune cells migrate into the infected-tissue and form early stages of TB granuloma. These structures recapitulate the distinct feature of human TB, the granuloma, which is fundamentally different or not commonly observed in widely used experimental animal models. This organotypic culture method enables the 3D visualization and robust quantitative analysis that provides pivotal information on spatial and temporal features of host cell-pathogen interactions. Taken together, the lung tissue model provides a physiologically relevant tissue micro-environment for studies on TB. Thus, the lung tissue model has potential implications for both basic mechanistic and applied studies. Importantly, the model allows addition or manipulation of individual cell types, which thereby widens its use for modelling a variety of infectious diseases that affect the lungs.

A 3D Human Lung Tissue Model for Functional Studies on Mycobacterium tuberculosis Infection

Human tuberculosis infection is a complex process, which is difficult to model in vitro. Here we describe a novel 3D human lung tissue model that recapitulates the dynamics that occur during infection, including the migration of immune cells and early granuloma formation in a physiological environment.

Tuberculosis (TB) still holds a major threat to the health of people worldwide, and there is a need for cost-efficient but reliable models to help us ...

System for Efficacy and Cytotoxicity Screening of Inhibitors Targeting Intracellular Mycobacterium tuberculosis

Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), is a leading cause of morbidity and mortality worldwide. With the increased spread of multi drug-resistant TB (MDR-TB), there is a real urgency to develop new therapeutic strategies against M. tuberculosis infections. Traditionally, compounds are evaluated based on their antibacterial activity under in vitro growth conditions in broth; however, results are often misleading for intracellular pathogens like M. tuberculosis since in-broth phenotypic screening conditions are significantly different from the actual disease conditions within the human body. Screening for inhibitors that work inside macrophages has been traditionally difficult due to the complexity, variability in infection, and slow replication rate of M. tuberculosis. In this study, we report a new approach to rapidly assess the effectiveness of compounds on the viability of M. tuberculosis in a macrophage infection model. Using a combination of a cytotoxicity assay and an in-broth M. tuberculosis viability assay, we were able to create a screening system that generates a comprehensive analysis of compounds of interest. This system is capable of producing quantitative data at a low cost that is within reach of most labs and yet is highly scalable to fit large industrial settings.

System for Efficacy and Cytotoxicity Screening of Inhibitors Targeting Intracellular Mycobacterium tuberculosis

We have developed a modular high-throughput screening system for discovering novel compounds against Mycobacterium tuberculosis, targeting intracellular and in-broth growing bacteria as well as cytotoxicity against the mammalian host cell.

Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), is a leading cause of morbidity and mortality worldwide. With the increased spread ...

A High-throughput Compatible Assay to Evaluate Drug Efficacy against Macrophage Passaged Mycobacterium tuberculosis

The early drug development process for anti-tuberculosis drugs is hindered by the inefficient translation of compounds with in vitro activity to effectiveness in the clinical setting. This is likely due to a lack of consideration for the physiologically relevant cellular penetration barriers that exist in the infected host. We recently established an alternative infection model that generates large macrophage aggregate structures containing densely packed M. tuberculosis (Mtb) at its core, which was suitable for drug susceptibility testing. This infection model is inexpensive, rapid, and most importantly BSL-2 compatible. Here, we describe the experimental procedures to generate Mtb/macrophage aggregate structures that would produce macrophage-passaged Mtb for drug susceptibility testing. In particular, we demonstrate how this infection system could be directly adapted to the 96-well plate format showing throughput capability for the screening of compound libraries against Mtb. Overall, this assay is a valuable addition to the currently available Mtb drug discovery toolbox due to its simplicity, cost effectiveness, and scalability.

A High-throughput Compatible Assay to Evaluate Drug Efficacy against Macrophage Passaged Mycobacterium tuberculosis

New models and assays that would improve the early drug development process for next-generation anti-tuberculosis drugs are highly desirable. Here, we describe a quick, inexpensive, and BSL-2 compatible assay to evaluate drug efficacy against Mycobacterium tuberculosis that can be easily adapted for high-throughput screening.

The early drug development process for anti-tuberculosis drugs is hindered by the inefficient translation of compounds with in vitro activity to ...

Analysis of 18FDG PET/CT Imaging as a Tool for Studying Mycobacterium tuberculosis Infection and Treatment in Non-human Primates

Mycobacterium tuberculosis remains the number one infectious agent in the world today. With the emergence of antibiotic resistant strains, new clinically relevant methods are needed that evaluate the disease process and screen for potential antibiotic and vaccine treatments. Positron Emission Tomography/Computed Tomography (PET/CT) has been established as a valuable tool for studying a number of afflictions such as cancer, Alzheimer&#39;s disease, and inflammation/infection. Outlined here are a number of strategies that have been employed to evaluate PET/CT images in cynomolgus macaques that are infected intrabronchially with low doses of M. tuberculosis. Through evaluation of lesion size on CT and uptake of 18F-fluorodeoxyglucose (FDG) in lesions and lymph nodes in PET images, these described methods show that PET/CT imaging can predict future development of active versus latent disease and the propensity for reactivation from a latent state of infection. Additionally, by analyzing the overall level of lung inflammation, these methods determine antibiotic efficacy of drugs against M. tuberculosis in the most clinically relevant existing animal model. These image analysis methods are some of the most powerful tools in the arsenal against this disease as not only can they evaluate a number of characteristics of infection and drug treatment, but they are also directly translatable to a clinical setting for use in human studies.

Analysis of 18FDG PET/CT Imaging as a Tool for Studying Mycobacterium tuberculosis Infection and Treatment in Non-human Primates

Here, we present a protocol to describe the analysis of 18F-FDG PET/CT imaging in non-human primates that have been infected with M. tuberculosis to study disease process, drug treatment, and disease reactivation.

Mycobacterium tuberculosis remains the number one infectious agent in the world today. With the emergence of antibiotic resistant strains, new clinically ...

Imaging Mycobacterium tuberculosis in Mice with Reporter Enzyme Fluorescence

Reporter enzyme fluorescence (REF) utilizes substrates that are specific for enzymes present in target organisms of interest for imaging or detection by fluorescence or bioluminescence. We utilize BlaC, an enzyme expressed constitutively by all M. tuberculosis strains. REF allows rapid quantification of bacteria in lungs of infected mice. The same group of mice can be imaged at many time points, greatly reducing costs, enumerating bacteria more quickly, allowing novel observations in host-pathogen interactions, and increasing statistical power, since more animals per group are readily maintained. REF is extremely sensitive due to the catalytic nature of the BlaC enzymatic reporter and specific due to the custom flourescence resonance energy transfer (FRET) or fluorogenic substrates used. REF does not require recombinant strains, ensuring normal host-pathogen interactions. We describe the imaging of M. tuberculosis infection using a FRET substrate with maximal emission at 800 nm. The wavelength of the substrate allows sensitive deep tissue imaging in mammals. We will outline aerosol infection of mice with M. tuberculosis, anesthesia of mice, administration of the REF substrate, and optical imaging. This method has been successfully applied to evaluating host-pathogen interactions and efficacy of antibiotics targeting M. tuberculosis.

Imaging Mycobacterium tuberculosis in Mice with Reporter Enzyme Fluorescence

We describe the optical imaging of mice infected with Mycobacterium tuberculosis (M. tuberculosis) using reporter enzyme fluorescence (REF). This protocol facilitates the sensitive and specific detection of M. tuberculosis in pre-clinical animal models for pathogenesis, therapeutics and vaccine research.

Reporter enzyme fluorescence (REF) utilizes substrates that are specific for enzymes present in target organisms of interest for imaging or detection by ...