Immunohistochemical detection of cytokines in paraffin-embedded mouse tissues

CD8 follicular T cells localize throughout the follicle during germinal center reactions and maintain cytolytic and helper properties

Follicular CXCR5+ PD-1+ CD8 T cells (CD8 Tfc) arise in multiple models of systemic autoimmunity yet their functional contribution to disease remains in debate. Here we define the follicular localization and functional interactions of CD8 Tfc with B cells during autoimmune disease. The absence of functional T regulatory cells in autoimmunity allows for CD8 Tfc development that then expands with lymphoproliferation. CD8 Tfc are identifiable within the lymph nodes and spleen during systemic autoimmunity, but not during tissue-restricted autoimmune disease. Autoimmune CD8 Tfc cells are polyfunctional, producing helper cytokines IL-21, IL-4, and IFNγ while maintaining cytolytic proteins CD107a, granzyme B, and TNF. During autoimmune disease, IL-2-KO CD8 T cells infiltrate the B cell follicle and germinal center, including the dark zone, and in vitro induce activation-induced cytidine deaminase in naïve B cells via IL-4 secretion. CD8 Tfc represent a unique CD8 T cell population with a diverse effector cytokine repertoire that can contribute to pathogenic autoimmune B cell response.

Proton pump inhibitors are not the key for therapying non-steroidal anti-inflammatory drugs-induced small intestinal injury

The ability of non-steroidal anti-inflammatory drugs (NSAIDs) to injure the small intestine has been well established in humans and animals. Proton pump inhibitors (PPIs) are frequently prescribed to reduce gastric and duodenal injury caused in high-risk patients taking NSAIDs. However, scarce information is available concerning the effects of PPIs on intestinal damage induced by NSAIDs, and the suppression of gastric acid secretion by PPIs is hard to provide any protection against the damage caused by NSAIDs in the small intestine. The present study was designed to examine the effects of intragastric treatment of two PPIs widely used in clinical practice, namely omeprazole and pantoprazole, on the intestinal damage induced by administration of diclofenac in rat. Male SD rats were treated with omeprazole or pantoprazole for 9 days, with concomitant treatment with anti-inflammatory doses of diclofenac on the final 5 days. The anatomical lesion, villous height, the thickness, and the section area of small intestine were quantitatively analyzed. The change of ultrastructural organization was observed. Endotoxin level in blood was measured by photometry. Epidermal growth factor was observed by immunohistochemistry. Omeprazole and pantoprazole didn't decrease the macroscopic and histologic damage induced by diclofenac in the rat's small intestine. In the two PPI groups, villous height was (89.6 ± 11.8 and 92.6 ± 19.3 μm) lower than which of the control group (P < 0.05). The thickness became thinning, and the section area became small. LPS levels in the portal blood of omeprazole and pantoprazole were (4.36 ± 1.26 and 4.25 ± 1.17 EU/ml), significantly higher than in controls (P < 0.05). The EFG of PPI group descended significantly compared with the control group (P < 0.05). Omeprazole and pantoprazole cannot protect the small intestine from the damage induced by diclofenac in the conscious rat. PPIs cannot repair NSAID-induced intestinal damage at least in part because of significant lesion in mechanical barrier function and reduction in epidermal growth factor.

Mucosal administration of the B subunit of E. coli heat-labile enterotoxin promotes the development of Foxp3-expressing regulatory T cells

Understanding the processes by which certain mucosal pathogens and their products induce regulatory T cells (Tregs) is important in determining mechanisms of pathogenicity and may point toward their use in treating immunological disorders. Accordingly, we have studied the events that follow mucosal administration of the B subunit of E. coli heat-labile enterotoxin (EtxB). EtxB modulates the response to co-administered antigens and can prevent autoimmune disease. Our data show that EtxB translocates across the nasal epithelium, modulating the expression of interleukin-10 (IL-10) and transforming growth factor-β(1) (TGF-β(1)). The modulated microenvironment drives an increase in Forkhead box P3 (Foxp3)-positive T cells, predominantly in the CD4(+)CD25(-) subset. Adoptive transfer experiments showed that enhanced Foxp3 expression was particularly evident in recently activated T cells by concomitant unrelated antigen challenge, and was both TGF-β(1) and IL-10 dependent. This ability to alter T-cell differentiation pathways following mucosal delivery explains how EtxB may modify mucosal immune environments and prevent unwanted pathologies.

Complicated urinary tract infection is associated with uroepithelial expression of proinflammatory protein S100A8

F344 rats chronically infected with Ureaplasma parvum develop two distinct profiles: asymptomatic urinary tract infection (UTI) and UTI complicated by struvite urolithiasis. To identify factors that affect disease outcome, we characterized the temporal host immune response during infection by histopathologic analysis and in situ localization of U. parvum. We also used differential quantitative proteomics to identify distinguishing host cellular responses associated with complicated UTI. In animals in which microbial colonization was limited to the mucosal surface, inflammation was indistinguishable from that which occurred in sham-inoculated controls, and the inflammation resolved by 72 h postinoculation (p.i.) in both groups. However, inflammation persisted in animals with microbial colonization that extended into the deeper layers of the submucosa. Proteome profiling showed that bladder tissues from animals with complicated UTIs had significant increases (P < 0.01) in proteins involved in apoptosis, oxidative stress, and inflammation. Animals with complicated UTIs (2 weeks p.i.) had the highest concentrations of the proinflammatory protein S100A8 (P Collapse

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MESH Headings

• Animals
• Calgranulin A/biosynthesis
• Cytokines/biosynthesis
• Histocytochemistry
• Humans
• Microscopy, Fluorescence
• Proteome/analysis
• Rats
• Ureaplasma/immunology
• Ureaplasma/pathogenicity
• Ureaplasma Infections/immunology
• Ureaplasma Infections/microbiology
• Ureaplasma Infections/pathology
• Urinary Bladder/immunology
• Urinary Bladder/microbiology
• Urinary Bladder/pathology
• Urinary Tract Infections/immunology
• Urinary Tract Infections/microbiology
• Urinary Tract Infections/pathology

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Grants

• K08 DK075651 NIDDK NIH HHS
• K08 DK075651-02 NIDDK NIH HHS
• R01 AI045875 NIAID NIH HHS
• K08DK075651 NIDDK NIH HHS

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Affiliation(s)

Leticia Reyes University of Florida, College of Veterinary Medicine, Department of Infectious Diseases & Pathology, P.O. Box 110880, Gainesville, FL 32611-0880, USA.
Sophie Alvarez
Ayman Allam
Mary Reinhard
Mary B Brown

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Different inflammatory responses are associated with Ureaplasma parvum-induced UTI and urolith formation

Background

Epidemiologic studies show a strong association between Ureaplasmas and urogenital tract disease in humans. Since healthy humans can be colonized with Ureaplasmas, its role as a pathogen remains controversial. In order to begin to define the role of the host in disease, we developed a rodent model of urinary tract infection (UTI) using Fischer 344 (F344) rats. Animals were inoculated with sterile broth, 10¹, 10³, 10⁵, 10⁷, or 10⁹ log CFU of a rat-adapted strain of Ureaplasma parvum.

Results

Infected animals exhibited two distinct profiles, asymptomatic UTI and UTI complicated with struvite urolithiasis. Inoculum dose of U. parvum affected the incidence of UTI, and 50% to 57% of animals inoculated with ≥ 10⁷ CFU of U. parvum remained infected (p < 0.04). However, inoculum dose did not influence immune response to U. parvum. Asymptomatic UTI was characterized by a minimal immune response that was predominantly monocytic and lymphocytic, with limited lesions, and elevated urinary levels of IFN-γ, IL-18 and MCP-1 (P ≤ 0.02). UTI complicated with struvite formation was characterized by an exaggerated immune response that was mostly neutrophilic (P ≤ 0.0001), with lesions that showed extensive uroepithelial hyperplasia (P ≤ 0.0001), and a predominance of IL-1α, IL-1β, and GRO/KC in the urine (P ≤ 0.02). Animals with asymptomatic UTI also had a significantly high rate of kidney infection (P ≤ 0.0005).

Conclusion

Complications associated with U. parvum infection are primarily dependent upon host-specific factors rather than Ureaplasma microbial load. The immune response in F344 rats is similar to that which occurs in humans with ureaplasmal associated disease. Therefore, this model of infection is a useful tool for elucidating U. parvum-host interactions that confer UTI and disease.

Topical levamisole hydrochloride therapy attenuates experimental murine allergic rhinitis

Allergic rhinitis is one of the most common chronic diseases. There are a number of effective therapeutic options for allergic rhinitis patients, such as intranasal corticosteroids. How to avoid the adverse effects of these traditional medicines has come to public attention and started the search for effective and safe medicine. We used BALB/c mice with experimental allergic rhinitis, and determined that levamisole delivered locally (intranasal, i.n.) could attenuate early-phase inflammatory response, decrease histamine, suppress edema and eosinophil infiltration, and diminish the ovalbumin-specific serum IgE level. Detailed analysis of cytokine gene expression showed that levamisole can decrease IL-4, IL-5 and IL-13 mRNA and increase IL-12, IL-18 and IFN-gamma mRNA. Levamisole showed analogous effects of down-regulating Th2 cytokines with budesonide and distinct up-regulating effects on Th1 cytokines gene expression. Our findings offer potential options for allergic rhinitis therapy.

Cytokine Expression in Paraffin Wax-embedded Tissues from Conventional Calves

The cross-reactivity of antibodies against human tumour necrosis factor (TNF)alpha, interleukin (IL)-1alpha, IL-1beta and porcine IL-6, and the distribution of immunolabelled cells were evaluated on paraffin wax-embedded tissues from five healthy calves. The tissues were fixed in 10% buffered formalin or Bouin's solution and processed for structural studies and immunohistochemical studies by the avidin-biotin-peroxidase technique. Bouin's solution proved to be the more suitable fixative and Tween 20 the most effective antigen unmasking technique for increasing detectable antigenicity. Constitutive expression of TNFalpha, IL-1alpha, IL-1beta and IL-6 by different cell populations, mainly macrophage-like cells, was detected. Lymphoid organs displayed a higher presence of immunolabelled cells than did lung, liver or kidney. TNFalpha and IL-1alpha appeared as the predominant cytokines, especially in the gut-associated lymphoid tissue of the ileum and in the regional mesenteric lymph nodes. The results will facilitate investigation of the role of these cytokine-producing cells in inflammatory disease processes in calves.

Contribution of the cornea to cytokine levels in the whole eye induced during the early phase of Pseudomonas aeruginosa challenge

Pseudomonas aeruginosa keratitis is one of the most destructive diseases of the cornea. The host response to this infection is critical to the outcome, and is regulated by cytokines produced in the ocular tissue. In this study, we assessed the relative contribution of the cytokines produced in the cornea to the inflammatory response of the whole eye to gain a better understanding of the inflammatory and regulatory processes in the ocular environment during localized corneal infection. C57BL/6 mice were challenged by topical application of P. aeruginosa to wounded corneas. Corneas and whole eyes were harvested 24 h post-challenge and bacterial numbers, myeloperoxidase levels and the levels of cytokines known to be important in keratitis were determined. The site of production of IL-6 and KC in the retina was determined by in situ hybridization. Before infection, 90% of macrophage inflammatory protein (MIP)-2 and approximately 80% of all IFN-gamma and IL-10 produced constitutively in the eye was found outside the cornea. Twenty-four hours after infection, bacterial numbers, levels of myeloperoxidase, and levels of MIP-2 and IL-1 were not different, whether measured in cornea or whole eye. However, expression of IL-6, KC, IFN-gamma and IL-10 was significantly greater in whole eyes than in the corneas of infected eyes. The cells expressing IL-6 and KC in the retina were identified by in situ hybridization. This study indicates that during corneal inflammation, the response of the whole eye as well as the cornea needs to be considered.

Development of organised conjunctival leucocyte aggregates after corneal transplantation in rats

AIM

To investigate the development of lymphoid aggregates in the conjunctiva after corneal transplantation in rats.

METHODS

LEW or PVG strain corneas were transplanted orthotopically to PVG rats. Cornea and conjunctiva were examined clinically for up to 42 days. Eyes were removed with attached conjunctiva on days 10 and 15 after transplantation (before and during rejection), together with normal eyes, fixed, paraffin embedded, and examined immunohistochemically.

RESULTS

Clinically, the temporal half of the upper palpebral conjunctiva of recipients of 10/19 allografts and 1/10 isografts developed pronounced swelling, correlating with inflammation and rejection. Histologically, the swelling comprised leucocytic aggregates with an altered overlying epithelium. Aggregates contained granulocytes, macrophages, and cells expressing major histocompatibility complex (MHC) class II, CD4, and CD8, all more numerous in allograft associated conjunctiva. Class II+ cells were more abundant at the surface, whereas macrophages and T cells were more numerous in the deeper stroma. There were few B cells. There was greater CD54 expression by vascular endothelium in allograft associated aggregates. Cells expressing TNFalpha and IFNgamma but not IL1beta were present in stromal and superficial areas.

CONCLUSIONS

Corneal transplantation in rats induces the development of organised conjunctival leucocytic aggregates in a fixed location that are significantly more pronounced in recipients of allografts compared with isografts and show characteristics of a Th1 type immune response. These aggregates have characteristics of conjunctiva associated lymphoid tissue and may be sites of presentation of graft antigens and lymphocyte proliferation at the ocular surface.

Experimental Pseudomonas aeruginosa keratitis in interleukin-10 gene knockout mice

Pseudomonas aeruginosa keratitis is one of the most destructive diseases of the cornea. The host response to this infection is critical to the outcome. The cytokine interleukin-10 (IL-10) is thought to play an important role in modulating excessive inflammation and antimicrobial defenses. We have found that in IL-10(-/-) mice there is a significant decrease in bacterial load in corneas at 7 days postchallenge with P. aeruginosa. This decrease was accompanied by a reduction in neutrophil numbers in the cornea and changes in cytokine levels compared to those of wild-type mice. A characteristic increase in neovascularization in the cornea was found in the IL-10(-/-) mice. This increased angiogenesis correlated with an increased expression of KC, whereas the kinetics of macrophage inflammatory peptide 2 expression correlated with neutrophil numbers. This finding suggests that KC may play a role in corneal angiogenesis. The source of IL-10 in mouse corneas was identified as a subpopulation of infiltrating cells and keratocytes. This study demonstrates that IL-10 plays an important role in regulating the balance of inflammatory mediators during P. aeruginosa infection of the cornea.

Pseudomonas aeruginosa keratitis in IL-6-deficient mice

BACKGROUND

Pseudomonas aeruginosa infection is one of the most destructive diseases of the eye. The host response to this infection is critical to the outcome. Interleukin-6 (IL-6) is implicated in this response; however, the mechanisms by which IL-6 contributes to the host defences in corneal infection remain unclear. Using IL-6-/- mice, we have explored the role of IL-6 in P. aeruginosa keratitis.

METHODS

The eyes of IL-6 gene knockout and wild-type mice were challenged topically with P. aeruginosa and examined on days 1-7. Keratitis was examined clinically and histologically. Cytokine, chemokine and complement 3 levels were determined by ELISA and ICAM-1 by immunohistochemistry.

RESULTS

Clinically, the IL-6-/- mice showed more severe disease than wild-type mice and this was supported by the histological findings. More than 2-fold higher bacterial load was detected in the eyes of the IL-6-/- mice than in those of the wild-type mice. Neutrophil infiltration to the central cornea of the IL-6-/- mice failed to occur in response to infection, although a greater number of neutrophils were present in the whole eye. This may in part be due to the reduced expression of the adhesion molecule ICAM-1 in the cornea, but does not appear to stem from insufficient production of chemokines or complement 3.

CONCLUSIONS

Our findings indicate that IL-6 is critical to the host defence of the cornea during P. aeruginosa infection. Pharmacological manipulation of the IL-6 response may represent a rational strategy for new interventions.

Primary herpes simplex virus type 1 infection of the eye triggers similar immune responses in the cornea and the skin of the eyelids

Herpetic stromal keratitis (HSK) and blepharoconjunctivitis in humans are thought partly to result from immunopathological responses to herpes simplex virus type 1 (HSV-1). The corneas of NIH mice were inoculated with HSV-1 (strain McKrae) and mice were examined for signs of disease and infection on days 1, 4, 7, 10, 14 and 21. The eyes and eyelids of infected and control mice were processed for immunohistochemistry and double stained for viral antigens and one of the following cell surface markers (Gr-1, F4/80, CD4, CD8, CD45R or MHC class II) or one of the following cytokines (IL-2, IL-4, IL-6, IL-10, IL-12 or IFN-gamma). All infected mice developed signs of HSK by day 4 and blepharitis by day 7 and these both persisted until day 21, when signs of resolution where apparent. Virus was detected during the first week of infection and became undetectable by day 10. Large numbers of Gr-1(+) cells (neutrophils) infiltrated infected corneas and eyelids in areas of viral antigen and CD4(+) T cells increased significantly in number after virus clearance. In both sites, the predominant cytokines were IL-6, IL-10, IL-12 and IFN-gamma, with few IL-2(+) and IL-4(+) cells. These observations suggest that the immune responses in the cornea are similar to those in the eyelids but, overall, the responses are not clearly characterized as either Th1 or Th2. In both sites, the neutrophil is the predominant infiltrating cell type and is a likely source of the cytokines observed and a major effector of the disease process.

Regulation of mucosal immune responses by recombinant interleukin 10 produced by intestinal epithelial cells in mice

BACKGROUND & AIMS

Interleukin (IL)-10 is a cytokine with anti-inflammatory properties. The aim of this study was to explore the effect of a site-specific delivery of IL-10 on intestinal immune responses.

METHODS

Transgenic mice were created in which IL-10 is expressed by the intestinal epithelial cells.

RESULTS

Transgenic mice showed a marked increase in the number of intraepithelial lymphocytes in the small intestine. Mucosal lymphocytes of transgenic animals produced fewer T helper type 1 cytokines than wild-type lymphocytes. By contrast, the production of transforming growth factor beta was increased. Moreover, the epithelial layer in transgenic mice was significantly enriched for CD4(+)CD25(+) T cells. Furthermore, transgenic mice had increased numbers of immunoglobulin A-producing B cells in the small intestine. These effects were local because splenic lymphocytes were not affected. Studies in models of inflammatory bowel disease showed that transgenic IL-10 was able to attenuate the acute colitis induced by dextran sodium sulfate administration or by adoptive transfer of CD4(+)CD45RB(high) splenocytes, with a modest effect on the chronic intestinal inflammation arising spontaneously in IL-10(-/-) mice.

CONCLUSIONS

These observations provide evidence for an in vivo lymphoepithelial cross talk, by which cytokines locally produced by epithelial cells can regulate immune responses in the intestine without systemic modifications.

Co-stimulatory requirements of effector T cells at inflammatory sites

There is a growing appreciation of the importance of T cell costimulation at inflammatory sites. Here, we briefly review the literature on the subject, and describe recent pertinent findings in our model of herpes simplex keratitis.

Epidermal growth factor reduces the development of necrotizing enterocolitis in a neonatal rat model

Necrotizing enterocolitis (NEC) is the most common gastrointestinal disease of prematurely born infants. Maternal milk plays an important protective role against NEC development and is the major source of epidermal growth factor (EGF) for neonates. The aim of this study was to examine the effect of orally administered EGF on the incidence of NEC in a neonatal rat model. Newborn rats were artificially fed either with growth factor-free rat milk substitute (RMS) or RMS supplemented with 500 ng/ml of EGF (RMS+EGF). Experimental NEC was induced by exposure to asphyxia and cold stress. Development of NEC was evaluated by gross and histological scoring of damage in the ileum. Ileal EGF receptor (EGF-R), EGF, and transforming growth factor-alpha mRNA expression was assessed by RT competitive-PCR, and the EGF-R was localized by immunohistochemistry. EGF supplementation of formula reduced the incidence and severity of NEC in rats (13/16 RMS vs. 4/13 RMS+EGF). Ileal EGF-R mRNA expression was markedly increased in the RMS group compared with RMS+EGF. Enhanced EGF-R expression in the RMS group was localized predominantly in the epithelial cells of injured ileum. These data suggest a new potential therapeutic approach for the prevention and treatment of NEC.

Differential production of IL-12, IFN-alpha, and IFN-gamma by mouse dendritic cell subsets

Dendritic cells (DC) not only stimulate T cells effectively but are also producers of cytokines that have important immune regulatory functions. In this study we have extended information on the functional differences between DC subpopulations to include differences in the production of the major immune-directing cytokines IL-12, IFN-alpha, and IFN-gamma. Splenic CD4(-)8(+) DC were identified as the major IL-12 producers in response to microbiological or T cell stimuli when compared with splenic CD4(-)8(-) or CD4(+)8(-) DC; however, all three subsets of DC showed similar IL-12 regulation and responded with increased IL-12 p70 production if IL-4 was present during stimulation. High level CD8 expression also correlated with extent of IL-12 production for DC isolated from thymus and lymph nodes. By using gene knockout mice we ruled out any role for CD8alpha itself, or of priming by T cells, on the superior IL-12-producing capacity of the CD8(+) DC. Additionally, CD8(+) DC were identified as the major producers of IFN-alpha compared with the two CD8(-) DC subsets, a finding that suggests similarity to the human plasmacytoid DC lineage. In contrast, the CD4(-)8(-) DC produced much more IFN-gamma than the CD4(-)8(+) or the CD4(+)8(-) DC under all conditions tested.

Pararosaniline fixation for detection of co-stimulatory molecules, cytokines, and specific antibody

Integral immunohistochemical analysis of immune responses in frozen sections requires that, in addition to constitutively expressed membrane CD markers, less stable determinants can be reliably visualized. Therefore, we compared the commonly used acetone fixation method with pararosaniline fixation for six determinant categories. These categories included selected constitutively expressed markers, inducible co-stimulatory molecules, pro- and anti-inflammatory cytokines (including the novel cytokine IL-18, also known as IGIF and IL-1gamma), antigen-specific antibody in plasma cells, bacterial peptidoglycan, and lysosomal acid phosphatase activity. Human spleen and mouse spleen activated by agonistic anti-CD40 antibody or TNP-Ficoll immunization were analyzed in parallel with brain tissue from multiple sclerosis (MS) patients and marmoset monkeys with experimental autoimmune encephalomyelitis (EAE), an animal model for MS. Fixation with pararosaniline resulted in better morphology of all tissues and inhibited endogenous alkaline phosphatase activity in brain tissue. Most determinants could be reliably detected. Staining sensitivity and intensity were markedly increased for selected determinant-tissue combinations, e.g., for IL-4 in human spleen and CD40 in human and mouse spleen. These data show that pararosaniline is a useful alternative to acetone, resulting in superior morphology and specific staining for selected determinant-tissue combinations. This provides additional flexibility for in situ analysis of immune reactivity.

Reactivation of herpes simplex virus type 1 in the mouse trigeminal ganglion: an in vivo study of virus antigen and cytokines

Reactivation of herpes simplex virus type 1 (HSV-1) in the trigeminal ganglion (TG) was induced by UV irradiation of the corneas of latently infected mice. Immunocytochemistry was used to monitor the dynamics of cytokine (interleukin-2 [IL-2], IL-4, IL-6, IL-10, gamma interferon [IFN-gamma], and tumor necrosis factor alpha [TNF-alpha]) and viral antigen production in the TG and the adjacent central nervous system on days 1 to 4, 6, 7, and 10 after irradiation. UV irradiation induced increased expression of IL-6 and TNF-alpha from satellite cells in uninfected TG. In latently infected TG, prior to reactivation, all satellite cells were TNF-alpha+ and most were also IL-6(+). Reactivation, evidenced by HSV-1 antigens and/or infiltrating immune cells, occurred in 28 of 45 (62%) TG samples. Viral antigens were present in the TG in neurons, often disintegrating on days 2 to 6 after irradiation. Infected neurons were usually surrounded by satellite cells and the foci of immune cells producing TNF-alpha and/or IL-6. IL-4(+) cells were detected as early as day 3 and were more numerous by day 10 (a very few IL-2(+) and/or IFN-gamma+ cells were seen at this time). No IL-10 was detected at any time. Our observations indicate that UV irradiation of the cornea may modulate cytokine production by satellite cells. We confirm that neurons are the site of reactivation and that they probably do not survive this event. The predominance of TNF-alpha and IL-6 following reactivation parallels primary infection in the TG and suggests a role in viral clearance. The presence of Th2-type cytokines (IL-4 and IL-6) indicates a role for antibody. Thus, several clearance mechanisms may be at work.