Name: a mouse model to assess innate immune response to staphylococcus aureus infection
Uploaded: 2019-02-28T14:00:00
Description: Watch this Scientific Journal Video about A Mouse Model to Assess Innate Immune Response to Staphylococcus aureus Infection at JoVE.com

This work was supported by National Institutes of Health Grants R01 AI129302 (to S.I.S.) and the Training Program in Pharmacology: From Bench to Bedside at UC Davis (NIH T32 GM099608 to L.S.A). The Molecular and Genomic Imaging (CMGI) at the University of California Davis provided superb technological support.

All mouse studies were reviewed and approved by the Institutional Animal Care and Use Committee at UC Davis and were performed according to the guidelines of the Animal Welfare Act and the Health Research Extension Act. Be sure to use sterile gloves when working with animals.
1. Mouse Source and Housing
<ol>
	<li>Derive LysM-eGFP mice on a C57BL/6J genetic background as described previously12. Derive LysM-EGFP&#215;MyD88-/- mice by crossing LysM-EGFP mice w...

<ol>
	<li>Moran, G. 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=Methicillin-Resistant+S.+aureus+Infections+among+Patients+in+the+Emergency+Department.">Methicillin-Resistant S. aureus Infections among Patients in the Emergency Department.</a> New England Journal of Medicine. 355 (7), 666-674 (2009).</li><li>Suaya, J. 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=Incidence+and+cost+of+hospitalizations+associated+with+Staphylococcus+aureus+skin+and+soft+tissue+infections+in+the+United+States+from+2001+through+2009.">Incidence and cost of hospitalizations associated with Staphylococcus aureus skin and soft tissue infections in the United States from 2001 through 2009.</a> BMC Infectious Diseases. 14 (1), 296 (2014).</li><li>Ventola, C. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+antibiotic+resistance+crisis:+part+1:+causes+and+threats.">The antibiotic resistance crisis: part 1: causes and threats.</a> P &amp; T : a Peer-Reviewed Journal for Formulary Management. 40 (4), 277-283 (2015).</li><li>Blaser, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antibiotic+use+and+its+consequences+for+the+normal+microbiome.">Antibiotic use and its consequences for the normal microbiome.</a> Science. 352 (6285), 544-545 (2016).</li><li>Hilliard, J. 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=Anti-Alpha-Toxin+Monoclonal+Antibody+and+Antibiotic+Combination+Therapy+Improves+Disease+Outcome+and+Accelerates+Healing+in+a+Staphylococcus+aureus+Dermonecrosis+Model.">Anti-Alpha-Toxin Monoclonal Antibody and Antibiotic Combination Therapy Improves Disease Outcome and Accelerates Healing in a Staphylococcus aureus Dermonecrosis Model.</a> Antimicrobial Agents and Chemotherapy. 59 (1), 299-309 (2015).</li><li>Proctor, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+developments+for+Staphylococcus+aureus+vaccines:+clinical+and+basic+science+challenges.">Recent developments for Staphylococcus aureus vaccines: clinical and basic science challenges.</a> European Cells &amp; Materials. 30, 315-326 (2015).</li><li>M&#246;lne, L., Verdrengh, M., Tarkowski, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+Neutrophil+Leukocytes+in+Cutaneous+Infection+Caused+by+Staphylococcus+aureus.">Role of Neutrophil Leukocytes in Cutaneous Infection Caused by Staphylococcus aureus.</a> Infection and Immunity. 68 (11), 6162-6167 (2000).</li><li>Kolaczkowska, E., Kubes, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neutrophil+recruitment+and+function+in+health+and+inflammation.">Neutrophil recruitment and function in health and inflammation.</a> Nature Reviews Immunology. 13 (3), 159-175 (2013).</li><li>Borregaard, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neutrophils,+from+Marrow+to+Microbes.">Neutrophils, from Marrow to Microbes.</a> Immunity. 33 (5), 657-670 (2010).</li><li>Miller, L. S., Cho, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immunity+against+Staphylococcus+aureus+cutaneous+infections.">Immunity against Staphylococcus aureus cutaneous infections.</a> Nature Reviews Immunology. 11 (8), 505-518 (2011).</li><li>Hasenberg, 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=Catchup:+a+mouse+model+for+imaging-based+tracking+and+modulation+of+neutrophil+granulocytes.">Catchup: a mouse model for imaging-based tracking and modulation of neutrophil granulocytes.</a> Nature Methods. 12 (5), 445-452 (2015).</li><li>Faust, N., Varas, F., Kelly, L. M., Heck, S., Graf, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insertion+of+enhanced+green+fluorescent+protein+into+the+lysozyme+gene+creates+mice+with+green+fluorescent+granulocytes+and+macrophages.">Insertion of enhanced green fluorescent protein into the lysozyme gene creates mice with green fluorescent granulocytes and macrophages.</a> Blood. 96 (2), 719-726 (2000).</li><li>Falahee, P. 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=&#945;-Toxin+Regulates+Local+Granulocyte+Expansion+from+Hematopoietic+Stem+and+Progenitor+Cells+in+Staphylococcus+aureus-Infected+Wounds.">&#945;-Toxin Regulates Local Granulocyte Expansion from Hematopoietic Stem and Progenitor Cells in Staphylococcus aureus-Infected Wounds.</a> Journal of immunology. 199 (5), 1772-1782 (2017).</li><li>Kim, M. -. H., 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=Dynamics+of+Neutrophil+Infiltration+during+Cutaneous+Wound+Healing+and+Infection+Using+Fluorescence+Imaging.">Dynamics of Neutrophil Infiltration during Cutaneous Wound Healing and Infection Using Fluorescence Imaging.</a> Journal of Investigative Dermatology. 128 (7), 1812-1820 (2008).</li><li>Liese, J., Rooijakkers, S. H. M., Strijp, J. A. G., Novick, R. P., Dustin, M. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intravital+two-photon+microscopy+of+host-pathogen+interactions+in+a+mouse+model+of+Staphylococcus+aureus+skin+abscess+formation.">Intravital two-photon microscopy of host-pathogen interactions in a mouse model of Staphylococcus aureus skin abscess formation.</a> Cellular Microbiology. 15 (6), 891-909 (2013).</li><li>Bogoslowski, A., Butcher, E. C., Kubes, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neutrophils+recruited+through+high+endothelial+venules+of+the+lymph+nodes+via+PNAd+intercept+disseminating+Staphylococcus+aureus.">Neutrophils recruited through high endothelial venules of the lymph nodes via PNAd intercept disseminating Staphylococcus aureus.</a> Proceedings of the National Academy of Sciences of the United States of America. 115 (10), 2449-2454 (2018).</li><li>Takeuchi, O., Hoshino, K., Akira, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cutting+Edge:+TLR2-Deficient+and+MyD88-Deficient+Mice+Are+Highly+Susceptible+to+Staphylococcus+aureus+Infection.">Cutting Edge: TLR2-Deficient and MyD88-Deficient Mice Are Highly Susceptible to Staphylococcus aureus Infection.</a> The Journal of Immunology. 165 (10), 5392-5396 (2000).</li><li>Miller, L. S., 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=MyD88+Mediates+Neutrophil+Recruitment+Initiated+by+IL-1R+but+Not+TLR2+Activation+in+Immunity+against+Staphylococcus+aureus.">MyD88 Mediates Neutrophil Recruitment Initiated by IL-1R but Not TLR2 Activation in Immunity against Staphylococcus aureus.</a> Immunity. 24 (1), 79-91 (2006).</li><li>Macedo, L., 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=Wound+healing+is+impaired+in+MyD88-deficient+mice:+a+role+for+MyD88+in+the+regulation+of+wound+healing+by+adenosine+A2A+receptors.">Wound healing is impaired in MyD88-deficient mice: a role for MyD88 in the regulation of wound healing by adenosine A2A receptors.</a> The American Journal of Pathology. 171 (6), 1774-1788 (2007).</li><li>Cho, J. S., 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=Neutrophil-derived+IL-1&#946;+Is+Sufficient+for+Abscess+Formation+in+Immunity+against+Staphylococcus+aureus+in+Mice.">Neutrophil-derived IL-1&#946; Is Sufficient for Abscess Formation in Immunity against Staphylococcus aureus in Mice.</a> PLoS Pathogens. 8 (11), e1003047 (2012).</li><li>Granick, J. L., 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=Staphylococcus+aureus+recognition+by+hematopoietic+stem+and+progenitor+cells+via+TLR2/MyD88/PGE2+stimulates+granulopoiesis+in+wounds.">Staphylococcus aureus recognition by hematopoietic stem and progenitor cells via TLR2/MyD88/PGE2 stimulates granulopoiesis in wounds.</a> Blood. 122 (10), 1770-1778 (2013).</li><li>Kim, M. H., 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=Neutrophil+survival+and+c-kit+-progenitor+proliferation+in+Staphylococcus+aureus-infected+skin+wounds+promote+resolution.">Neutrophil survival and c-kit+-progenitor proliferation in Staphylococcus aureus-infected skin wounds promote resolution.</a> Blood. 117 (12), 3343-3352 (2011).</li><li>Foster, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immune+evasion+by+staphylococci.">Immune evasion by staphylococci.</a> Nature Reviews Microbiology. 3 (12), 948-958 (2005).</li><li>Gordon, R. J., Lowy, F. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pathogenesis+of+Methicillin-Resistant+Staphylococcus+aureus+Infection.">Pathogenesis of Methicillin-Resistant Staphylococcus aureus Infection.</a> Clinical Infectious Diseases. 46 (Supplement_5), S350-S359 (2008).</li><li>Cho, J. S., 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=Neutrophil-derived+IL-1&#946;+Is+Sufficient+for+Abscess+Formation+in+Immunity+against+Staphylococcus+aureus+in+Mice.">Neutrophil-derived IL-1&#946; Is Sufficient for Abscess Formation in Immunity against Staphylococcus aureus in Mice.</a> PLoS Pathogens. 8 (11), e1003047-e1003020 (2012).</li><li>Bernthal, N. M., 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=A+mouse+model+of+post-arthroplasty+Staphylococcus+aureus+joint+infection+to+evaluate+in+vivo+the+efficacy+of+antimicrobial+implant+coatings.">A mouse model of post-arthroplasty Staphylococcus aureus joint infection to evaluate in vivo the efficacy of antimicrobial implant coatings.</a> PLoS ONE. 5 (9), e12580 (2010).</li><li>Plaut, R. D., Mocca, C. P., Prabhakara, R., Merkel, T. J., Stibitz, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stably+Luminescent+Staphylococcus+aureus+Clinical+Strains+for+Use+in+Bioluminescent+Imaging.">Stably Luminescent Staphylococcus aureus Clinical Strains for Use in Bioluminescent Imaging.</a> PLoS ONE. 8 (3), e59232 (2013).</li><li>Dillen, C. 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=Clonally+expanded+&#947;&#948;+T+cells+protect+against+Staphylococcus+aureus+skin+reinfection.">Clonally expanded &#947;&#948; T cells protect against Staphylococcus aureus skin reinfection.</a> The Journal of Clinical Investigation. 128 (3), 1026-1042 (2018).</li></ol>

S. aureus infection models that utilize bioluminescent S. aureus infection in a fluorescent neutrophil reporter mouse in conjunction with advanced techniques of whole animal in vivo optical imaging have advanced our knowledge of the innate immune response to infection. Previous studies using the LysM-EGFP mouse have shown that up to 1 x 107 neutrophils recruit to an S. aureus infected wound over the first 24 h of infection14, and wound-recruited neutrophils ex...

Staphylococcus aureus (S. aureus) accounts for the majority of skin and soft tissue infections (SSTIs) in the United States1. The incidence of methicillin-resistant S. aureus (MRSA) infections has increased steadily over the past two decades2, motivating the study of the mechanisms of persistence and the discovery of new treatment strategies. The standard of care for MRSA infections is systemic antibiotic therapy, but MRSA has become increasingly resistant to antibiotics over time3 and these drugs can diminish the host&#39;s beneficial microbiome, causing negative health effects, especially in children4. Preclinical studies have examined alternative strategies to treat MRSA infections5, but translating these approaches to the clinic has proved challenging due to emergence of virulence factors that thwart host immune responses6. To dissect the host-pathogen dynamics that drive S. aureus SSTIs, we combine noninvasive and longitudinal readouts of the number of neutrophils recruited to the wound bed with kinetic measures of bacterial abundance and wound area.
Neutrophils are the most abundant circulating leukocyte in humans and the first responders to a bacterial infection7. Neutrophils are a necessary component for an effective host response against S. aureus infections due to their bactericidal mechanisms, including production of reactive oxygen species, proteases, antimicrobial peptides and functional responses including phagocytosis and neutrophil extracellular trap production8,9. Human patients with genetic defects in neutrophil function, such as chronic granulomatous disease and Chediak-Higashi syndrome, show an increased susceptibility to S. aureus infection. In addition, patients with genetic (such as congenital neutropenia) and acquired (such as neutropenia seen in chemotherapy patients) defects in neutrophil numbers are also highly susceptible to S. aureus infection10. Given the importance of neutrophils in clearing S. aureus infections, enhancing their immune capacity or tuning their numbers within a S. aureus lesion may prove an effective strategy in resolving infection.
Over the past decade, transgenic mice with fluorescence neutrophil reporters have been developed to study their trafficking11,12. Combining neutrophil reporter mice with whole animal imaging techniques permits spatiotemporal analysis of neutrophils in tissues and organs. When combined with bioluminescent strains of S. aureus, it is possible to track the accumulation of neutrophils in response to S. aureus abundance and persistence in the context of bacterial virulence factors that directly and indirectly perturb neutrophil numbers in affected tissue13,14,15,16.
Mice are less susceptible to S. aureus virulence and immune evasion mechanisms than humans. As such, wild-type mice may not be an ideal animal model to investigate the efficacy of a given therapeutic to treat chronic S. aureus infection. MyD88-deficient mice (i.e., MyD88-/- mice), an immunocompromised mouse strain that lacks functional interleukin-1 receptor (IL-1R) and Toll-like receptor (TLR) signaling, show greater susceptibility to S. aureus infection compared to wild-type mice17 and an impairment in neutrophil trafficking to a site of S. aureus infection in the skin18. Development of a mouse strain that possesses a fluorescent neutrophil reporter in MyD88-/- mice has provided an alternative model for investigating the efficacy of therapies to treat S. aureus infection compared to current neutrophil reporter mice.
In this protocol, we characterize S. aureus infection in the immunocompromised LysM-EGFP&#215;MyD88-/- mice, and compare the time course and resolution of infection with the LysM-EGFP mice. LysM-EGFP&#215;MyD88-/- mice develop a chronic infection that does not resolve, and 75% succumb to infection after 8 days. A significant defect in initial neutrophil recruitment occurs over 72 h of the inflammatory phase of infection, and 50% fewer neutrophils recruit during the latter stage of infection. The increased susceptibility of the LysM-EGFP&#215;MyD88-/- mice makes this particular strain a rigorous preclinical model to evaluate the efficacy of new therapeutic techniques targeting S. aureus infection compared to current models that utilize wild-type mice, especially techniques aiming to boost the innate immune response against infection.

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a mouse model to assess innate immune response to staphylococcus aureus infection

Staphylococcus aureus (S. aureus)&#160;infections, including methicillin resistant stains, are an enormous burden on the healthcare system. With incidence rates of S. aureus infection climbing annually, there is a demand for additional research in its&#160;pathogenicity. Animal models of infectious disease advance our understanding of the host-pathogen response and lead to the development of effective therapeutics. Neutrophils play a primary role in the innate immune response that controls S. aureus infections by forming an abscess to wall off the infection and facilitate bacterial clearance; the number of neutrophils that infiltrate an S. aureus skin infection often correlates with disease outcome. LysM-EGFP mice, which possess the enhanced green fluorescent protein (EGFP) inserted in the Lysozyme M (LysM) promoter region (expressed primarily by neutrophils), when used in conjunction with in vivo whole animal fluorescence imaging (FLI) provide&#160;a means of quantifying neutrophil emigration noninvasively and longitudinally into wounded skin. When combined with a bioluminescent S. aureus strain and sequential in vivo whole animal bioluminescent imaging (BLI), it is possible to longitudinally monitor both the neutrophil recruitment dynamics and in vivo bacterial burden at the site of infection in anesthetized mice from onset of infection to resolution or death. Mice are more resistant to a number of virulence factors produced by S. aureus that facilitate effective colonization and infection in humans. Immunodeficient mice provide a more sensitive animal model to examine persistent S. aureus infections and the ability of therapeutics to boost innate immune responses. Herein, we characterize responses in LysM-EGFP mice that have been bred to MyD88-deficient mice (LysM-EGFP&#215;MyD88-/- mice) along with wild-type LysM-EGFP mice to investigate S. aureus skin wound infection. Multispectral simultaneous detection enabled study of neutrophil recruitment dynamics by using in vivo FLI, bacterial burden by using in vivo BLI, and wound healing longitudinally and noninvasively over time.

LysM-EGFP&#215;MyD88-/- mice are more susceptible to S. aureus infection than LysM-EGFP mice
The strain of S. aureus used in this study, ALC290618, was constructed with a plasmid that contains the lux construct that produces bioluminescent signals from live and actively metabolizing bacteria. When inoculated into mice, in vivo bioluminescence imaging (BLI) techn...

Watch this Scientific Journal Video about A Mouse Model to Assess Innate Immune Response to Staphylococcus aureus Infection at JoVE.com

A Mouse Model to Assess Innate Immune Response to Staphylococcus aureus Infection

An approach is described for real-time detection of the innate immune response to cutaneous wounding and Staphylococcus aureus infection of mice. By comparing LysM-EGFP mice (which possess fluorescent neutrophils) with a LysM-EGFP crossbred immunodeficient mouse strain, we advance our understanding of infection and the development of approaches to combat infection.

A Mouse Model to Assess Innate Immune Response to Staphylococcus aureus Infection

Staphylococcus aureus (S. aureus)&#160;infections, including methicillin resistant stains, are an enormous burden on the healthcare system. With incidence ...

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An attenuated West Nile virus (WNV), a nonstructural (NS) 4B-P38G mutant, induced higher innate cytokine and T cell responses than the wild-type WNV in ...

Non-invasive Imaging of the Innate Immune Response in a Zebrafish Larval Model of Streptococcus iniae Infection

Non-invasive Imaging of the Innate Immune Response in a Zebrafish Larval Model of Streptococcus iniae Infection

The aquatic pathogen, Streptococcus iniae, is responsible for over 100 million dollars in annual losses for the aquaculture industry and is capable of ...

A Galleria mellonella Oral Administration Model to Study Commensal-Induced Innate Immune Responses

A Galleria mellonella Oral Administration Model to Study Commensal-Induced Innate Immune Responses

The investigation of the immunogenic potential of commensal bacteria on the host immune system is one essential component when studying intestinal ...

Quantifying the Cytotoxicity of Staphylococcus aureus Against Human Polymorphonuclear Leukocytes

Quantifying the Cytotoxicity of Staphylococcus aureus Against Human Polymorphonuclear Leukocytes

Staphylococcus aureus is capable of secreting a wide range of leukocidins that target and disrupt the membrane integrity of polymorphonuclear leukocytes ...

Isolation of Tonsillar Mononuclear Cells to Study Ex Vivo Innate Immune Responses in a Human Mucosal Lymphoid Tissue

Studying isolated cells from mucosa-associated lymphoid tissues (MALT) allows understanding of immune cells response in pathologies involving mucosal ...