Endogenous innate sensor NLRP3 is a key component in peritoneal macrophage dynamics required for cestode establishment.

The NLRP3 receptor can assemble inflammasome platforms to trigger inflammatory responses; however, accumulating evidence suggests that it can also display anti-inflammatory properties. Here, we explored the role of nucleotide-binding oligomerization domain pyrin-containing protein 3 (NLRP3) in Taenia crassiceps experimental infection, which requires immune polarization into a Th2-type profile and peritoneal influx of suppressive macrophages for successful colonization. NLRP3 deficient mice (NLRP3-/-) were highly resistant against T. crassiceps, relative to wild-type (WT) mice. Resistance in NLRP3-/- mice was associated with a diminished IL-4 output, high levels of IL-15, growth factor for both innate and adaptive lymphocytes, and a dramatic decrease in peritoneum-infiltrating suppressive macrophages. Also, a transcriptional analysis on bone marrow-derived macrophages exposed to Taenia-secreted antigens and IL-4 revealed that NLRP3-/- macrophages express reduced transcripts of relm-α and PD-1 ligands, markers of alternative activation and suppressive ability, respectively. Finally, we found that the resistance displayed by NLRP3-/- mice is transferred through intestinal microbiota exchange, since WT mice co-housed with NLRP3-/- mice were significantly more resistant than WT animals preserving their native microbiota. Altogether, these data demonstrate that NLRP3 is a component of innate immunity required for T. crassiceps to establish, most likely contributing to macrophage recruitment, and controlling lymphocyte-stimulating cytokines such as IL-15.

Macrophage Migration Inhibitory Factor (MIF) is a Key Player in Dry Eye Disease.

PURPOSE: To explore the role of the proinflammatory cytokine, macrophage migration inhibitory factor (MIF), in a murine model of dry eye disease (DED). METHODS: The role of MIF on DED was determined using genetically MIF deficient mice and pharmacological inhibition of MIF. DED was induced with 0.5 mg of scopolamine via subcutaneous injection in wild type (WT) and mice lacking MIF (Mif-/-), three times a day for 21 days. DED signs, tear volume, ferning pattern and cytology impression were evaluated. Also, eye tissues were collected to determine transcripts of key inflammatory mediators and histopathological damage. In a second set of experiments, we neutralized MIF with ISO-1, an isozaxiline-derivative MIF tautomerase activity-inhibiting small molecule in WT mice, following an acute DED model for 10 days. ISO-1 was given starting on day 3 after DED induction and signs were evaluated, including a recovery phase in both experimental approaches. RESULTS: When compared to WT, Mif-/- mice showed attenuated signs of DED like preserved mucin pattern and increased tear volume. Also, Mif-/- mice maintained conjunctival epithelial cells and less corneal damage, associated with lower levels of TNFα and IL-1ß. At recovery phase, Mif-/- mice presented improved signs. Interestingly, in cornea and conjunctiva the absence of MIF selectively downregulated the transcription of inflammatory enzymes like inos and nox4 whereas displayed enhanced transcripts of il-4, il-13, tgfß and cox2. Finally, pharmacological inhibition of MIF using ISO-1, replicated the above findings in the mouse model. CONCLUSION: MIF is a central positive mediator of the inflammatory process in experimental DED, thus, targeting MIF could be used as a novel therapy in ocular surface inflammatory pathologies.

Mast Cells in Immune-Mediated Cholangitis and Cholangiocarcinoma.

Cholestasis, which is impaired bile flow from the liver into the intestine, can be caused by cholangitis and/or bile duct obstruction. Cholangitis can arise from bacterial infections and cholelithiasis, however, immune-mediated cholangitis in primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) is characterized by a strong immune response targeting the biliary epithelial cells (BECs). Persistent biliary inflammation further represents a risk for biliary neoplasia, cholangiocarcinoma (CCA) by driving chronic cellular stress in the BECs. Currently, immune-mediated cholangitis is considered a Th1-Th17-dominant disease, however, the presence of Th2-related mast cells (MCs) in tissue samples from PBC, PSC and CCA patients has been described, showing that these MCs are active players in these diseases. Here, we reviewed and discussed experimental and clinical data supporting a pro-fibrotic role for MCs in immune-mediated cholangitis as well as their participation in supporting tumor growth acting as angiogenesis promoters. Thus, although MCs have classically been identified as downstream effectors of Th2 responses in allergies and parasitic infections, evidence suggests that these MCs are relevant players in biliary inflammation and neoplasia. The availability of strategies to prevent MCs' activation represents a therapeutic opportunity in biliary diseases.

NLRP3 receptor contributes to protection against experimental antigen-mediated cholangitis.

Inflammatory diseases of the bile ducts like primary sclerosing colangitis (PSC) are characterized by a robust cellular response targeting the biliary epithelium leading to chronic inflammation and fibrosis. Driving fibro-inflammatory diseases, NOD-like receptors such as NLRP3 have been identified as a central component to immune-mediated pathology. However, to date the role of NLRP3 in biliary diseases has been poorly explored. Here, we addressed the role of NLRP3 in the OVAbil mouse model of antigen-mediated cholangitis. As obesity continues to spread worldwide, we also evaluated the NLRP3 response in experimental cholangitis after high-fat diet exposure. We compared the extent of histopathological liver damage between OVAbil and OVAbilxNLRP3-/- mice after either a standard chow or a high-fat diet. Infiltrating immune cells were characterized by flow cytometry and levels of cytokines, chemokines and liver enzymes in blood samples were analyzed at the end of the experiment. We observed a more severe histopathological phenotype of cholangitis in absence of NLRP3, characterized by loss of bile ducts and larger inflammatory foci and higher levels of IL- 6 and CXCL10 as compared with NLRP3 sufficient mice. This phenotype was further exaggerated in the context of obesity, where cholangitis induced in NLRP3-deficient obese mice resulted in further exacerbated histopathology and increased levels of IL-13 and TNFα, suggesting a diet-specific profile. The absence of NLRP3 caused a supressed IL-17 response. In summary, our data suggest that activation of NLRP3 attenuates this antigen-mediated OVAbil model of cholangitis.

Comparison of Glucose and Satiety Hormone Response to Oral Glucose vs. Two Mixed-Nutrient Meals in Rats.

The obesity epidemic is driving interest in identifying strategies that enhance appetite control by altering the secretion of hormones that regulate satiety and food intake. An appropriate nutrient stimulus, such as a meal or oral nutrient solution, is needed to elicit the secretion of satiety hormones in order to evaluate the impact of dietary and other interventions. Our objective was to compare the effects of oral glucose vs. mixed nutrients on plasma concentrations of glucose and appetite-regulating hormones to determine the most appropriate oral nutrient challenge to trigger robust hormone secretion. A 120 min oral glucose tolerance test (OGTT) was compared with two meal tolerance tests (MTT) of differing formulation to evaluate glucose and satiety hormone responses. Following overnight feed deprivation, male Sprague-Dawley rats were given one of three oral gavages with equal carbohydrate content (2 g CHO/kg) in the form of: (1) Dextrose, (2) Ensure®, or (3) Mixed Meal. A fourth group was given saline as a control. Blood was collected via tail snip and analyzed for glucose, insulin, GLP-1, GIP, PYY, amylin, leptin, and ghrelin. Dextrose resulted in the highest blood glucose at T15 (P = 0.014), while the mixed meal was significantly higher than saline from T30-T120 (P < 0.05). Insulin was higher at T15 with dextrose compared to saline (P = 0.031) and Ensure® (P = 0.033). GLP-1 tAUC was significantly higher with dextrose compared to mixed meal (P = 0.04) while GIP tAUC was higher with dextrose and mixed meal compared to saline (P < 0.05). Changes in tAUC for insulin, amylin, leptin, ghrelin, and PYY did not reach significance. Based on these findings, dextrose appears to provide a robust acute glycemic and hormone response and is therefore likely an appropriate oral solution to reproducibly test the impact of various dietary, surgical, or pharmacological interventions on glucose and satiety hormone response.

Innate and Adaptive Cell Populations Driving Inflammation in Dry Eye Disease.

Dry eye disease (DED) is the most common ocular disease and affects millions of individuals worldwide. DED encompasses a heterogeneous group of diseases that can be generally divided into two forms including aqueous-deficient and evaporative DED. Evidence suggests that these conditions arise from either failure of lacrimal gland secretion or low tear film quality. In its secondary form, DED is often associated with autoimmune diseases such as Sjögren's syndrome and rheumatoid arthritis. Current treatment strategies for DED are limited to anti-inflammatory medications that target the immune system as the source of deleterious inflammation and tissue injury. However, there is a lack of understanding of the underlying pathogenesis of DED, and subsequently, there are very few effective treatment strategies. The gap in our knowledge of the etiology of primary DED is in part because the majority of research in DED focused on secondary autoimmune causes. This review focuses on what is currently understood about the contribution of innate and adaptive immune cell populations in the pathogenesis of DED and highlights the need to continue investigating the central role of immunity driving DED.

Neutralization of IL-15 abrogates experimental immune-mediated cholangitis in diet-induced obese mice.

Obesity is a global epidemic affecting chronic inflammatory diseases. Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease that can occur as an extraintestinal manifestation of inflammatory bowel disease (IBD). Previously we reported that patients with PSC who are obese have a higher risk of advanced liver disease. Currently it is unknown how obesity accelerates or worsens PSC. We evaluated the progression of PSC in an antigen-driven cholangitis mouse model of diet-induced obesity. Obesity was induced in our murine model of immune-mediated cholangitis (OVAbil). OVAbil mice were fed standard chow or high-fat/sucrose diet for twelve weeks followed by induction of biliary inflammation by OVA-specific T cell transfer. Histopathological damage in portal tracts was scored and serum collected. Neutralizing antibodies against IL-15 were administered daily until study termination. Obese mice developed exacerbated liver inflammation and damage. Immune cell phenotyping in liver revealed greater numbers of neutrophils and CD8+ T cells in obese mice. Higher levels of cytokines and chemokines were found in obese mice with cholangitis. Immuno-neutralizing antibodies against IL-15 greatly attenuated cholangitis in obese mice. Obesity exacerbated experimental PSC in part by overproduction of IL-15. Timely targeting of IL-15 may slow the progression of PSC.