Name: preparation of murine submandibular salivary gland for upright intravital microscopy
Uploaded: 2018-05-07T12:30:00
Description: Watch this Scientific Journal Video about Preparation of Murine Submandibular Salivary Gland for Upright Intravital Microscopy at JoVE.com

This work was funded by Swiss National Foundation (SNF) project grant 31003A_135649, 31003A_153457 and 31003A_172994 (to JVS), and Leopoldina fellowship LPDS 2011-16 (to BS). This work benefitted from optical setups of the "Microscopy Imaging Center" (MIC) of the University of Bern.

All animal work has been approved by the Cantonal Committee for Animal Experimentation and conducted according to federal guidelines.
1. Anesthetize the Mouse
<ol>
	<li>Wear personal protective equipment, including lab coat and gloves.</li>
	<li>Mix ketamine, xylazine, and saline to a working concentration of 20 mg/mL and 1 mg/mL, respectively. Inject the working stock intraperitoneally (i.p.) at 8-10 &#181;L/g of mouse. Place the mouse back into the cage. 
	NOTE: This protocol has been...

<ol>
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This protocol offers a straightforward approach for in vivo imaging of murine submandibular and sublingual salivary glands using upright non-linear microscopy often used in the field of immunology. The method can be adapted for the imaging of other exocrine glands in the head and neck region. For instance, our lab has performed imaging of the lacrimal gland in an analogous manner (not shown).
Removing the connective tissue around the SMG is the most critical step of this protocol, sin...

Saliva is secreted by exocrine glands to lubricate food, protect the mucosal surfaces of the oral tract, and to deliver digestive enzymes as well as antimicrobial substances1,2. In addition to minor salivary glands interspersed in the oral submucosa, there are three bilateral sets of major glands identified as parotid, sublingual, and submandibular, according to their location1,2. Pyramid-shaped epithelial cells, organized into flask-shaped sacs (acini) or demilunes that are surrounded by myoepithelial cells and a basement membrane, secrete the serous and mucous components of saliva1. The narrow luminal space of the acini drains into intercalated ducts, which unite into striated ducts until they finally join into a single excretory duct1. The main excretory duct of the SMG is called Wharton&#39;s duct (WD) and opens into the sublingual caruncle3,4. The SMG epithelial compartment therefore represents a highly arborized structure with manifold terminal endpoints, resembling a bundle of grapes1,5,6. The SMG interstitium is composed of blood and lymphatic vessels embedded in connective tissue7 containing parasympathetic nerves8 and extracellular matrix5. Normal human and rodent salivary glands also contain T cells, macrophages, and dendritic cells9, as well as plasma cells that secrete Immunoglobulin A (IgA) into the saliva9,10. Due to its multifaceted functions in health and disease, the SMG is a subject of interest for many fields of biological research, including dentistry4, immunology11, oncology12, physiology8, and cell biology3.
Imaging of dynamic cellular processes and interactions is a powerful tool in biological research13,14. The development of deep tissue imaging and innovations inmicroscopes based on nonlinear optics (NLO), which rely on scattering or absorption of multiple photons by the sample, has allowed to directly examine cellular processes in complex tissues13,15. Absorption of multiple photons involves delivery of the total excitation energy by low energy photons, which confines fluorophore excitation to the focal plane and thus allows deeper tissue penetration with reduced photodamage and noise from out of focus excitation13,15. This principle is employed by two-photon microscopy (2PM) and allows for imaging of fluorescent specimens in depths of up to 1 mm15,16. While commercially available 2PM setups have become user-friendly and reliable, the major challenge for intravital imaging is to carefully expose and stabilize the target organ of anesthetized mice, especially for imaging of time lapse series. Several methods for digital drift correction after data acquisition have been published17,18 and we recently developed &#34;VivoFollow&#34;, an automated correction system, which counteracts slow tissue drift in real time using a computerized stage19. However, it is still critical for high quality imaging to minimize tissue motion, especially fast movements caused by breathing or heartbeat19. Preparation and stabilization procedures have been published for multiple organs, including spinal cord20, liver21, skin22, lung23, and lymph node24. Furthermore, models for rat salivary gland imaging have been developed3,25 and further refined for high resolution intravital imaging of the murine SMG tailored to an inverted microscope setup26,27,28.
Here, we present a practical and adaptable protocol for intravital imaging of the murine SMG using upright nonlinear microscopy, which is commonly used for intravital imaging in the field of immunology. To this end, we modified a widely employed immobilization stage used for popliteal lymph node preparations.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Narketan 10 %&#160; (Ketamine) 20ml (100 mg/ml)</td>
			<td>Vetoquinol</td>
			<td>3605877535982</td>
			<td></td>
		</tr>
		<tr>
			<td>Rompun 2% (Xylazine) 25 ml (20 mg/ml)</td>
			<td>Bayer</td>
			<td>680538150144</td>
			<td></td>
		</tr>
		<tr>
			<td>Saline NaCl 0.9%</td>
			<td>B. Braun</td>
			<td>3535789</td>
			<td></td>
		</tr>
		<tr>
			<td>Prequillan 1% (Acepromazine) 10 ml (10 mg/ml)</td>
			<td>Fatro</td>
			<td>6805671900029</td>
			<td></td>
		</tr>
		<tr>
			<td>Electric shaver</td>
			<td>Wahl</td>
			<td>9818L</td>
			<td>or similar</td>
		</tr>
		<tr>
			<td>Hair removal cream</td>
			<td>Veet</td>
			<td>4002448090656</td>
			<td></td>
		</tr>
		<tr>
			<td>Durapore Surgical tape (2.5 cm x 9.1 m and 1.25 cm x 9.1 m)</td>
			<td>Durapore (3M)</td>
			<td>1538-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Durapore Surgical tape (2.5 cm x 9.1 m and 1.25 cm x 9.1 m)</td>
			<td>Durapore (3M)</td>
			<td>1538-0</td>
			<td></td>
		</tr>
		<tr>
			<td>Super glue Ultra gel, instantaneous glue</td>
			<td>Pattex, Henkel</td>
			<td>4015000415040</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope cover glass slides 20 mm and 22 mm</td>
			<td>Menzel-Gl&#228;ser</td>
			<td>631-1343/ 631-1344</td>
			<td></td>
		</tr>
		<tr>
			<td>Grease for laboratories 60 g glisseal N</td>
			<td>Borer (VWR supplier)</td>
			<td>DECO514215.00-CA15</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical scissors</td>
			<td>Fine Science Tools (F.S.T )</td>
			<td>14090-09</td>
			<td>or similar</td>
		</tr>
		<tr>
			<td>Fine Forceps</td>
			<td>Fine Science Tools (F.S.T )</td>
			<td>11252-20</td>
			<td>or similar</td>
		</tr>
		<tr>
			<td>Cotton swab</td>
			<td>Migros</td>
			<td>617027988254</td>
			<td>or similar</td>
		</tr>
		<tr>
			<td>Gauze Gazin 5 x 5 cm</td>
			<td>Lohmann and Rauscher</td>
			<td>18500</td>
			<td>or similar</td>
		</tr>
		<tr>
			<td>Stereomicroscope</td>
			<td>Leica</td>
			<td>MZ16</td>
			<td>or similar</td>
		</tr>
		<tr>
			<td>Texas Red dextran 70kDa</td>
			<td>&#160;Molecular Probes</td>
			<td>D1864</td>
			<td></td>
		</tr>
		<tr>
			<td>Cascade Blue dextran 10kDa</td>
			<td>invitrogen</td>
			<td>D1976</td>
			<td></td>
		</tr>
		<tr>
			<td>Two-photon system</td>
			<td>LaVision Biotec</td>
			<td>TrimScope I and II</td>
			<td>or similar</td>
		</tr>
		<tr>
			<td>XLUMPLANFL 20x/0.95 W objective</td>
			<td>Olympus</td>
			<td>n/a</td>
			<td>or other water immersion objective&#160;</td>
		</tr>
		<tr>
			<td>Digital thermometer</td>
			<td>Fluke</td>
			<td>95969077651</td>
			<td></td>
		</tr>
	</tbody>
</table>

preparation of murine submandibular salivary gland for upright intravital microscopy

The submandibular salivary gland (SMG) is one of the three major salivary glands, and is of interest for many different fields of biological research, including cell biology, oncology, dentistry, and immunology. The SMG is an exocrine gland comprised of secretory epithelial cells, myofibroblasts, endothelial cells, nerves, and extracellular matrix. Dynamic cellular processes in the rat and mouse SMG have previously been imaged, mostly using inverted multi-photon microscope systems. Here, we describe a straightforward protocol for the surgical preparation and stabilization of the murine SMG in anesthetized mice for in vivo imaging with upright multi-photon microscope systems. We present representative intravital image sets of endogenous and adoptively transferred fluorescent cells, including the labeling of blood vessels or salivary ducts and second harmonic generation to visualize fibrillar collagen. In sum, our protocol allows for surgical preparation of mouse salivary glands in upright microscopy systems, which are commonly used for intravital imaging in the field of immunology.

This protocol allows imaging of almost the entire dorsal or ventral side of the SMG. The field of view typically also includes the sublingual salivary gland, which differs slightly from the SMG in cellular composition4. Both glands are encapsulated by fibrillar collagen and subdivided into lobes. Most 2PM systems can produce a label-free image of fibrillar collagen by measuring the 2nd harmonic signal, but usually fluorescent molecules are needed for vis...

Watch this Scientific Journal Video about Preparation of Murine Submandibular Salivary Gland for Upright Intravital Microscopy at JoVE.com

Preparation of Murine Submandibular Salivary Gland for Upright Intravital Microscopy

We describe a protocol to surgically expose and stabilize the murine submandibular salivary gland for intravital imaging using upright intravital microscopy. This protocol is easily adaptable to other exocrine glands of the head and neck region of mice and other small rodents.

The submandibular salivary gland (SMG) is one of the three major salivary glands, and is of interest for many different fields of biological research, ...

The overall goal of this surgical procedure is to prepare the murine submandibular salivary gland for upright intravital microscopy. This method can help answer questions in any field of research that uses the submandibular salivary gland as a model organ, for instance immunology. The main advantage of this technique it allows for surgical preparation of salivary gland for upright intravital microscopy which is widely used in the field of immunology.First, use an electric razor to remove fur from the shaving area on a C57 black six mouse. Then dab a cotton swab with hair removal cream and apply it on the shaved area. After about three minutes, use wet tissues to thoroughly remove the cream from the shaved area.Next, remove the holders for the heating ring and the removable coverslip holder to prepare the stage for fixing the mouse. Then loosen the screws of the ear bar and the fixed coverslip holders. Next, tape a piece of gauze on the center of the stage to prepare a bedding for the mouse.Use glue to attach a 20 millimeter diameter coverglass to the top of a cylindrical metal holder forming the lower coverglass. Then glue a 25 millimeter coverglass to the bottom of a flat metal holder forming the upper coverglass. Next, position the mouse with its back on the gauze perpendicular to the stretched string and the head centered between the ear bars.Next, use a surgical tape to fix the upper portion of the mouse on the stage. Then hook the string in the upper front incisors, tightening the string til the jaw reaches a horizontal position. Next, use angled curved forceps to carefully pull out the tongue to ensure breathing.Then pull the tail tightly and tape it on the stage. Next, align the ear bars such that an approximately 30 degree angle is established between the bar in the edge of the stage. To do so, draw two right and left 30 degree angles on a paper sheet.Then position the transparent stage on the paper to align the holders. Keep moving the left and right bars inward simultaneously to fix the jaws in an immobile position and then tighten the screw. Keep an eye on the chest movement before, during, and after fixing the jaw.Place a heating lamp nearby or a heating pad underneath the stage to heat the mouse. First, try to locate a slight bulge in the skin to identify the right submandibular salivary gland. Then use fine forceps to lift the skinfold at the center of the bulge and create an incision approximately five millimeters long.Next, use a syringe with 25 gauge hypodermic needle filled with vacuum grease to apply a four millimeter high ring of vacuum grease along the surface of the cut. Fill the grease ring with the saline to leave the tissue moist. Then sit under a stereomicroscope and use one forceps to firmly hold the connective tissue connected to the gland and use another forceps to pull the distal connective tissue for it to rupture.Continue disrupting the connective tissue on the top of the gland and then the medial section. Then remove the lateral connective tissue counterclockwise around the gland from the medial to the rostral section. Beginners usually struggle most with disrupting the connective tissue surrounding the gland without damaging the gland itself.Next, use forceps to pull the connective tissue attached to the gland upwards to lift the caudal part of the gland. Then disrupt the connective tissue below the submandibular lobe from the caudal towards the rostral end. After confirming the absence of leakage from the grease ring, position the lower coverglass attached to the metal bar to its height adjustable holder.Maintain an angle of 60 degrees with the mouse while positioning the holder from the caudal direction. Then lower the coverglass for it to contact the gland. Complete the grease ring on top of the coverglass to form a new saline reservoir.Next, use forceps to carefully pinch the connective tissue attached to the submandibular lobe and pull it on top of the coverslip. Maintain the grease ring at a height of four millimeters in order to prevent leakage. Check such that the coverglass holder for the upper coverglass is in its upper position.Then use a screw to attach the metal bar with the 25 millimeter upper coverglass to the holder. To position the submandibular gland in the center, use the adjustable screws of the holder to place the coverglass. Using the screws of the adjustable holder, lower the top coverglass to touch the submandibular gland.Then note the shape and color of the gland. Next, look for possible air bubbles or drops of saline outside the reservoir to rule out leakage. Then tighten all the fixation screws.During the routine use of this protocol, the critical step is to adjust the coverslip and the grease to form a perfect seal chamber without pressing the salivary gland too much or too little. Then insert a temperature probe inside the reservoir such that it's close to the gland and tape the probe wire to the stage. With the submandibular gland positioned in the center, apply a grease ring to the top coverslip.Then position the heating ring on top of the coverslip and seal with the grease. Finally, tape the tubing of the heating ring to the stage. Here, the vasculature of the submandibular gland and fibroblast-like cells expressing the reporter COL1A1 green fluorescent protein is demonstrated.In the fluorescence image, the blood vessels are labeled by intravenous injection of Texas Red Dextran conjugate whereas the fibrillar collagen present in between two lobes can be detected as the second harmonic signal. In this image, the ductal lumen is labeled with Cascade Blue Dextran after injecting it into the Wharton's duct and the green fluorescent protein tag CD8 positive T cells are also visible to show the presence of T cells in the murine salivary glands. These are the sequences of the GFP tag CD8 positive tissue resident memory T cells.These CD8 positive T cells migrate in the submandibular salivary gland. The blood vessels in the gland are labeled by intravenous injection of Texas Red Dextran and the cell nuclei are stained with Hoechst. Once mastered, this technique can be done in 30 to 40 minutes if performed properly.While attempting this procedure, it is important to regularly control vital signs of the mouse and the anesthesia. This procedure can be used in combination with many other methods like the adoptive transfer of fluorescently labeled immune cells to answer additional questions like the migration of immune cells in salivary gland parenchyme. This technique paved the way for researchers in the field of immunology to explore tissue resident memory T cell migration in the salivary gland.After watching this video, you should have a good understanding of how to surgically prepare submandibular salivary gland for upright intravital microscopy.

preparation-murine-submandibular-salivary-gland-for-upright

Research

JoVE Journal

Immunology and Infection

Intravital Microscopy of the Inguinal Lymph Node

Lymph nodes (LN's), located throughout the body, are an integral component of the immune system. They serve as a site for induction of adaptive immune response and therefore, the development of effector cells. As such, LNs are key to fighting invading pathogens and maintaining health. The choice of LN to study is dictated by accessibility and the desired model; the inguinal lymph node is well situated and easily supports studies of biologically relevant models of skin and genital mucosal infection.
The inguinal LN, like all LNs, has an extensive microvascular network supplying it with blood. In general, this microvascular network includes the main feed arteriole of the LN that subsequently branches and feeds high endothelial venules (HEVs). HEVs are specialized for facilitating the trafficking of immune cells into the LN during both homeostasis and infection. How HEVs regulate trafficking into the LN under both of these circumstances is an area of intense exploration. The LN feed arteriole, has direct upstream influence on the HEVs and is the main supply of nutrients and cell rich blood into the LN. Furthermore, changes in the feed arteriole are implicated in facilitating induction of adaptive immune response. The LN microvasculature has obvious importance in maintaining an optimal blood supply to the LN and regulating immune cell influx into the LN, which are crucial elements in proper LN function and subsequently immune response. 
The ability to study the LN microvasculature in vivo is key to elucidating how the immune system and the microvasculature interact and influence one another within the LN. Here, we present a method for in vivo imaging of the inguinal lymph node. We focus on imaging of the microvasculature of the LN, paying particular attention to methods that ensure the study of healthy vessels, the ability to maintain imaging of viable vessels over a number of hours, and quantification of vessel magnitude. Methods for perfusion of the microvasculature with vasoactive drugs as well as the potential to trace and quantify cellular traffic are also presented. 
Intravital microscopy of the inguinal LN allows direct evaluation of microvascular functionality and real-time interface of the direct interface between immune cells, the LN, and the microcirculation. This technique potential to be combined with many immunological techniques and fluorescent cell labelling as well as manipulated to study vasculature of other LNs.

A technique for performing intravital microscopy of the inguinal lymph node (LN) is outlined. Such technique allows for real-time, in vivo study of the lymph node microvasculature and structure both during homeostasis and infection. This technique can be adapted to cell trafficking studies and to other lymph node sites.

Lymph nodes (LN's), located throughout the body, are an integral component of the immune system. They serve as a site for induction of adaptive immune ...

Intravital Imaging of the Mouse Thymus using 2-Photon Microscopy

Two-photon Microscopy (TPM) provides image acquisition in deep areas inside tissues and organs. In combination with the development of new stereotactic tools and surgical procedures, TPM becomes a powerful technique to identify "niches" inside organs and to document cellular "behaviors" in live animals. While intravital imaging provides information that best resembles the real cellular behavior inside the organ, it is both more laborious and technically demanding in terms of required equipment/procedures than alternative ex vivo imaging acquisition. Thus, we describe a surgical procedure and novel "stereotactic" organ holder that allows us to follow the movements of Foxp3+ cells within the thymus.
Foxp3 is the master regulator for the generation of regulatory T cells (Tregs). Moreover, these cells can be classified according to their origin: ie. thymus-differentiated Tregs are called "naturally-occurring Tregs" (nTregs), as opposed to peripherally-converted Tregs (pTregs). Although significant amount of research has been reported in the literature concerning the phenotype and physiology of these T cells, very little is known about their in vivo interactions with other cells. This deficiency may be due to the absence of techniques that would permit such observations. The protocol described in this paper provides a remedy for this situation.
Our protocol consists of using nude mice that lack an endogenous thymus since they have a punctual mutation in the DNA sequence that compromises the differentiation of some epithelial cells, including thymic epithelial cells. Nude mice were gamma-irradiated and reconstituted with bone marrows (BM) from Foxp3-KIgfp/gfp mice. After BM recovery (6 weeks), each animal received embryonic thymus transplantation inside the kidney capsule. After thymus acceptance (6 weeks), the animals were anesthetized; the kidney containing the transplanted thymus was exposed, fixed in our organ holder, and kept under physiological conditions for in vivo imaging by TPM. We have been using this approach to study the influence of drugs in the generation of regulatory T cells.

We have developed novel laboratory tools and protocols for intravital imaging acquisition of the thymus. Our technique should help in the identification of &#x201C;niches&#x201D; within the thymus where T cell development occurs.

Two-photon Microscopy (TPM) provides image acquisition in deep areas inside tissues and organs. In combination with the development of new stereotactic ...

Intravital Microscopy of the Spleen: Quantitative Analysis of Parasite Mobility and Blood Flow

The advent of intravital microscopy in experimental rodent malaria models has allowed major advances to the knowledge of parasite-host interactions 1,2. Thus, in vivo imaging of malaria parasites during pre-erythrocytic stages have revealed the active entrance of parasites into skin lymph nodes 3, the complete development of the parasite in the skin 4, and the formation of a hepatocyte-derived merosome to assure migration and release of merozoites into the blood stream 5. Moreover, the development of individual parasites in erythrocytes has been recently documented using 4D imaging and challenged our current view on protein export in malaria 6. Thus, intravital imaging has radically changed our view on key events in Plasmodium development. Unfortunately, studies of the dynamic passage of malaria parasites through the spleen, a major lymphoid organ exquisitely adapted to clear infected red blood cells are lacking due to technical constraints.
Using the murine model of malaria Plasmodium yoelii in Balb/c mice, we have implemented intravital imaging of the spleen and reported a differential remodeling of it and adherence of parasitized red blood cells (pRBCs) to barrier cells of fibroblastic origin in the red pulp during infection with the non-lethal parasite line P.yoelii 17X as opposed to infections with the P.yoelii 17XL lethal parasite line 7. To reach these conclusions, a specific methodology using ImageJ free software was developed to enable characterization of the fast three-dimensional movement of single-pRBCs. Results obtained with this protocol allow determining velocity, directionality and residence time of parasites in the spleen, all parameters addressing adherence in vivo. In addition, we report the methodology for blood flow quantification using intravital microscopy and the use of different colouring agents to gain insight into the complex microcirculatory structure of the spleen. 
Ethics statement
All the animal studies were performed at the animal facilities of University of Barcelona in accordance with guidelines and protocols approved by the Ethics Committee for Animal Experimentation of the University of Barcelona CEEA-UB (Protocol No DMAH: 5429). Female Balb/c mice of 6-8 weeks of age were obtained from Charles River Laboratories.

We show the method for performing intravital microscopy of the spleen using GFP transgenic malaria parasites and the quantification of parasite mobility and blood flow within this organ.

The advent of intravital microscopy in experimental rodent malaria models has allowed major advances to the knowledge of parasite-host interactions 1,2. ...

Saliva, Salivary Gland, and Hemolymph Collection from Ixodes scapularis Ticks

Ticks are found worldwide and afflict humans with many tick-borne illnesses. Ticks are vectors for pathogens that cause Lyme disease and tick-borne relapsing fever (Borrelia spp.), Rocky Mountain Spotted fever (Rickettsia rickettsii), ehrlichiosis (Ehrlichia chaffeensis and E. equi), anaplasmosis (Anaplasma phagocytophilum), encephalitis (tick-borne encephalitis virus), babesiosis (Babesia spp.), Colorado tick fever (Coltivirus), and tularemia (Francisella tularensis) 1-8. To be properly transmitted into the host these infectious agents differentially regulate gene expression, interact with tick proteins, and migrate through the tick 3,9-13. For example, the Lyme disease agent, Borrelia burgdorferi, adapts through differential gene expression to the feast and famine stages of the tick's enzootic cycle 14,15. Furthermore, as an Ixodes tick consumes a bloodmeal Borrelia replicate and migrate from the midgut into the hemocoel, where they travel to the salivary glands and are transmitted into the host with the expelled saliva 9,16-19.
As a tick feeds the host typically responds with a strong hemostatic and innate immune response 11,13,20-22. Despite these host responses, I. scapularis can feed for several days because tick saliva contains proteins that are immunomodulatory, lytic agents, anticoagulants, and fibrinolysins to aid the tick feeding 3,11,20,21,23. The immunomodulatory activities possessed by tick saliva or salivary gland extract (SGE) facilitate transmission, proliferation, and dissemination of numerous tick-borne pathogens 3,20,24-27. To further understand how tick-borne infectious agents cause disease it is essential to dissect actively feeding ticks and collect tick saliva. This video protocol demonstrates dissection techniques for the collection of hemolymph and the removal of salivary glands from actively feeding I. scapularis nymphs after 48 and 72 hours post mouse placement. We also demonstrate saliva collection from an adult female I. scapularis tick.

Saliva, Salivary Gland, and Hemolymph Collection from Ixodes scapularis Ticks

The collection of infected tick hemolymph, salivary glands, and saliva is important to study how tick-borne pathogens cause disease. In this protocol we demonstrate how to collect hemolymph and salivary glands from feeding Ixodes scapularis nymphs. We also demonstrate saliva collection from female I. scapularis adults.

Ticks are found worldwide and afflict humans with many tick-borne illnesses. Ticks are vectors for pathogens that cause Lyme disease and tick-borne ...

Highly Resolved Intravital Striped-illumination Microscopy of Germinal Centers

Monitoring cellular communication by intravital deep-tissue multi-photon microscopy is the key for understanding the fate of immune cells within thick tissue samples and organs in health and disease. By controlling the scanning pattern in multi-photon microscopy and applying appropriate numerical algorithms, we developed a striped-illumination approach, which enabled us to achieve 3-fold better axial resolution and improved signal-to-noise ratio, i.e. contrast, in more than 100 &#181;m tissue depth within highly scattering tissue of lymphoid organs as compared to standard multi-photon microscopy. The acquisition speed as well as photobleaching and photodamage effects were similar to standard photo-multiplier-based technique, whereas the imaging depth was slightly lower due to the use of field detectors. By using the striped-illumination approach, we are able to observe the dynamics of immune complex deposits on secondary follicular dendritic cells &#8211; on the level of a few protein molecules in germinal centers.

High-resolution intravital imaging with enhanced contrast up to 120 &#181;m depth in lymph nodes of adult mice is achieved by spatially modulating the excitation pattern of a multi-focal two-photon microscope. In 100 &#181;m depth we measured resolutions of 487 nm (lateral) and 551 nm (axial), thus circumventing scattering and diffraction limits.

Monitoring cellular communication by intravital deep-tissue multi-photon microscopy is the key for understanding the fate of immune cells within thick ...

Intravital Microscopy Imaging of the Liver following Leishmania Infection: An Assessment of Hepatic Hemodynamics

Intravital microscopy (IVM) is a powerful optical imaging technique that has made possible the visualization, monitoring and quantification of various biological events in real time and in live animals. This technology has greatly advanced our understanding of physiological processes and pathogen-mediated phenomena in specific organs.
In this study, IVM is applied to the mouse liver and protocols are designed to image in vivo the circulatory system of the liver and measure red blood cell (RBC) velocity in individual hepatic vessels. To visualize the different vessel subtypes that characterize the hepatic organ and perform blood flow speed measurements, C57Bl/6 mice are intravenously injected with a fluorescent plasma reagent that labels the liver-associated vasculature. IVM enables in vivo, real time, measurement of RBC velocity in a specific vessel of interest. Establishing this methodology will make it possible to investigate liver hemodynamics under physiological and pathological conditions. Ultimately, this imaging-based methodology will be important for studying the influence of L. donovani infection&#160;on hepatic hemodynamics.
This method can be applied to other infectious models and mouse organs and might be further extended to pre-clinical testing of a drug&#8217;s effect on inflammation by quantifying its effect on blood flow.

Intravital Microscopy Imaging of the Liver following Leishmania Infection: An Assessment of Hepatic Hemodynamics

This article reports on a detailed method for the dynamic measurement and quantification of blood flow velocity within individual blood vessels of the mouse liver vasculature using intravital microscopy imaging in combination with a specific methodology for image acquisition and analysis.

Intravital microscopy (IVM) is a powerful optical imaging technique that has made possible the visualization, monitoring and quantification of various ...

Long Term Intravital Multiphoton Microscopy Imaging of Immune Cells in Healthy and Diseased Liver Using CXCR6.Gfp Reporter Mice

Liver inflammation as a response to injury is a highly dynamic process involving the infiltration of distinct subtypes of leukocytes including monocytes, neutrophils, T cell subsets, B cells, natural killer (NK) and NKT cells. Intravital microscopy of the liver for monitoring immune cell migration is particularly challenging due to the high requirements regarding sample preparation and fixation, optical resolution and long-term animal survival. Yet, the dynamics of inflammatory processes as well as cellular interaction studies could provide critical information to better understand the initiation, progression and regression of inflammatory liver disease. Therefore, a highly sensitive and reliable method was established to study migration and cell-cell-interactions of different immune cells in mouse liver over long periods (about 6 hr) by intravital two-photon laser scanning microscopy (TPLSM) in combination with intensive care monitoring.
The method provided includes a gentle preparation and stable fixation of the liver with minimal perturbation of the organ; long term intravital imaging using multicolor multiphoton microscopy with virtually no photobleaching or phototoxic effects over a time period of up to 6 hr, allowing tracking of specific leukocyte subsets; and stable imaging conditions due to extensive monitoring of mouse vital parameters and stabilization of circulation, temperature and gas exchange.
To investigate lymphocyte migration upon liver inflammation CXCR6.gfp knock-in mice were subjected to intravital liver imaging under baseline conditions and after acute and chronic liver damage induced by intraperitoneal injection(s) of carbon tetrachloride (CCl4).
CXCR6 is a chemokine receptor expressed on lymphocytes, mainly on Natural Killer T (NKT)-, Natural Killer (NK)- and subsets of T lymphocytes such as CD4 T cells but also mucosal associated invariant (MAIT) T cells1. Following the migratory pattern and positioning of CXCR6.gfp+ immune cells allowed a detailed insight into their altered behavior upon liver injury and therefore their potential involvement in disease progression.

Stable intravital high-resolution imaging of immune cells in the liver is challenging. Here we provide a highly sensitive and reliable method to study migration and cell-cell-interactions of immune cells in mouse liver over long periods (about 6 hours) by intravital multiphoton laser scanning microscopy in combination with intensive care monitoring.

Liver inflammation as a response to injury is a highly dynamic process involving the infiltration of distinct subtypes of leukocytes including monocytes, ...

A Method for the Measurement of Salivary Gland Function in Mice

Patients with Sj&#246;gren&#39;s syndrome, an autoimmune disease affecting the exocrine glands, develop salivary gland inflammation and have reduced saliva production. Similarly, saliva production is severely compromised in patients receiving radiation treatment for head and neck cancers. Rodent models, developed to mimic these clinical conditions, facilitate an understanding of the disease pathogenesis and allow for the development of new therapeutic strategies. Therefore, the ability to accurately, reproducibly, and repeatedly measure salivary gland function in animal models is critical. Building on procedures previously described in the literature, a method was developed that meets these criteria and was used to evaluate salivary gland function in mice. An additional advantage of this new method is that it is easily mastered, and has little inter-operator variation. Salivary gland function is evaluated as the amount (weight or volume) or rate (mL/min) of saliva produced in response to pilocarpine stimulation. The collected saliva is a good source for the analyses of protein content, immunoglobulin concentrations, and other biomolecules.

Salivary gland hypofunction is a frequent consequence of autoimmune disease and radiation therapy. Reproducible evaluation of salivary gland function in mouse models of these diseases is a technical challenge. Here, a simple method for accurate and reproducible measurement of saliva production in mice is described.

Patients with Sj&#246;gren&#39;s syndrome, an autoimmune disease affecting the exocrine glands, develop salivary gland inflammation and have reduced ...

Imaging Cell Interaction in Tracheal Mucosa During Influenza Virus Infection Using Two-photon Intravital Microscopy

The analysis of cell-cell or cell-pathogen interaction in vivo is an important tool to understand the dynamics of the immune response to infection. Two-photon intravital microscopy (2P-IVM) allows the observation of cell interactions in deep tissue in living animals, while minimizing the photobleaching generated during image acquisition. To date, different models for 2P-IVM of lymphoid and non-lymphoid organs have been described. However, imaging of respiratory organs remains a challenge due to the movement associated with the breathing cycle of the animal.
Here, we describe a protocol to visualize in vivo immune cell interactions in the trachea of mice infected with influenza virus using 2P-IVM. To this purpose, we developed a custom imaging platform, which included the surgical exposure and intubation of the trachea, followed by the acquisition of dynamic images of neutrophils and dendritic cells (DC) in the mucosal epithelium. Additionally, we detailed the steps needed to perform influenza intranasal infection and flow cytometric analysis of immune cells in the trachea. Finally, we analyzed neutrophil and DC motility as well as their interactions during the course of a movie. This protocol allows for the generation of stable and bright 4D images necessary for the assessment of cell-cell interactions in the trachea.

In this study, we present a protocol to perform two-photon intravital imaging and cell interaction analysis in the murine tracheal mucosa after infection with influenza virus. This protocol will be relevant for researchers studying immune cell dynamics during respiratory infections.

The analysis of cell-cell or cell-pathogen interaction in vivo is an important tool to understand the dynamics of the immune response to infection. ...

Intravital Imaging of Intraepithelial Lymphocytes in Murine Small Intestine

Intraepithelial lymphocytes expressing &#947;&#948; T cell receptor (&#947;&#948; IEL) play a key role in immune surveillance of the intestinal epithelium. Due in part to the lack of a definitive ligand for the &#947;&#948; T cell receptor, our understanding of the regulation of &#947;&#948; IEL activation and their function in vivo remains limited. This necessitates the development of alternative strategies to interrogate signaling pathways involved in regulating &#947;&#948; IEL function and the responsiveness of these cells to the local microenvironment. Although &#947;&#948; IELs are widely understood to limit pathogen translocation, the use of intravital imaging has been critical to understanding the spatiotemporal dynamics of IEL/epithelial interactions at steady-state and in response to invasive pathogens. Herein, we present a protocol for visualizing IEL migratory behavior in the small intestinal mucosa of a GFP &#947;&#948; T cell reporter mouse using inverted spinning disk confocal laser microscopy. Although the maximum imaging depth of this approach is limited relative to the use of two-photon laser-scanning microscopy, spinning disk confocal laser microscopy provides the advantage of high speed image acquisition with reduced photobleaching and photodamage. Using 4D image analysis software, T cell surveillance behavior and their interactions with neighboring cells can be analyzed following experimental manipulation to provide additional insight into IEL activation and function within the intestinal mucosa.

We describe a method to visualize GFP-labeled &#947;&#948; IELs using intravital imaging of murine small intestine by inverted spinning disk confocal microscopy. This technique enables the tracking of live cells within the mucosa for up to 4 h and can be used to investigate a variety of intestinal immune-epithelial interactions. &#160;