Treatment with P28GST, a schistosome-derived enzyme, after acute colitis induction in mice: Decrease of intestinal inflammation associated with a down regulation of Th1/Th17 responses.

BACKGROUND: P28GST, a 28Kd glutathione S-transferase enzymatic protein derived from a schistosome helminth prevents experimental colitis when administered subcutaneously in the presence of adjuvant by decreasing pro-inflammatory Th1/Th17 response. Given the antioxidant properties of P28GST, we evaluated its anti-inflammatory potential when administered locally after colitis induction in the absence of adjuvant. METHODS: Colitis was induced in BALB/c mice by rectal administration of TNBS, followed by two intraperitoneal injections of P28GST at day 1 and day 2. Mice were sacrificed 48h after TNBS administration and evaluated for macroscopic and histological scores, myeloperoxidase (MPO) quantification and cytokine messenger RNA expression in the colonic tissues. RESULTS: Both clinical and histological scores significantly decreased in mice treated with P28GST at 5 or 50µg/kg when compared to vehicle- treated mice. A significant reduction of MPO was detected in colonic tissues from P28GST-treated mice, similarly to mice treated with methylprednisolone as the reference treatment. Pro-inflammatory cytokines TNF, IL-1ß, and IL-6, mRNA as well as serum levels were down-regulated in mice colonic tissues treated with P28GST at 5 or 50µg/kg. In addition, a significant decrease of mRNA expression levels of T-bet, and ROR-γ, respective markers of Th1 and Th17 cells was observed. Whereas no significant effect was detected on Gata3 mRNA, a marker of Th2 cells, the Arg/iNOS mRNA levels significantly increased in P28GST-treated mice, suggesting the induction of M2 macrophages. CONCLUSIONS: These findings provide evidence that P28GST injected locally after colitis induction induces a potent decrease of colitis inflammation in mice, associated to downregulation of Th1/Th17 response, and induction of anti-inflammatory alternatively activated macrophages.

IL-18 Is Involved in Eosinophil-Mediated Tumoricidal Activity against a Colon Carcinoma Cell Line by Upregulating LFA-1 and ICAM-1.

Eosinophils are multifunctional leukocytes that are involved in innate and adaptive immune responses through the expression of various receptors and mediators. Previously, we showed that human eosinophils and T cells shared cytotoxic activities against tumor cells that involved the γ-δ TCR and cell-cell contact. In this study, we investigated the molecules involved in eosinophil-tumor cell interactions. Given the role of IL-18 in cell adhesion and in protecting against colon cancer, we evaluated its role in eosinophil-mediated cytotoxicity against Colo-205, a human colon carcinoma cell line. We found that human eosinophils exerted dose- and time-dependent tumoricidal activity against Colo-205 cells. Neutralization of IL-18 significantly reduced eosinophil-mediated Colo-205 apoptosis and inhibited cell-cell adhesion. Moreover, addition of rIL-18 led to upregulation of CD11a and ICAM-1 adhesion molecules, which were involved in the contact between eosinophils and Colo-205 cells. Our results indicated that IL-18 was involved in the eosinophil-mediated death of Colo-205 by facilitating contact between effector and target cells. These data underscored the involvement of an additional mediator in eosinophil-mediated antitumor cytotoxicity. Our findings support existing evidence that eosinophils could play a beneficial role in the context of colon cancer.

Single-molecule analysis of the major glycopolymers of pathogenic and non-pathogenic yeast cells.

Most microbes are coated with carbohydrates that show remarkable structural variability and play a crucial role in mediating microbial-host interactions. Understanding the functions of cell wall glycoconjugates requires detailed knowledge of their molecular organization, diversity and heterogeneity. Here we use atomic force microscopy (AFM) with tips bearing specific probes (lectins, antibodies) to analyze the major glycopolymers of pathogenic and non-pathogenic yeast cells at molecular resolution. We show that non-ubiquitous ß-1,2-mannans are largely exposed on the surface of native cells from pathogenic Candida albicans and C. glabrata, the former species displaying the highest glycopolymer density and extensions. We also find that chitin, a major component of the inner layer of the yeast cell wall, is much more abundant in C. albicans. These differences in molecular properties, further supported by flow cytometry measurements, may play an important role in strengthening cell wall mechanics and immune interactions. This study demonstrates that single-molecule AFM, combined with immunological and fluorescence methods, is a powerful platform in fungal glycobiology for probing the density, distribution and extension of specific cell wall glycoconjugates. In nanomedicine, we anticipate that this new form of AFM-based nanoglycobiology will contribute to the development of sugar-based drugs, immunotherapeutics, vaccines and diagnostics.

The CARD8 p.C10X mutation associates with a low anti-glycans antibody response in patients with Crohn's disease.

BACKGROUND: Crohn's disease (CD) is associated with elevated anti-glycans antibody response in 60% of CD patients, and 25% of healthy first-degree relatives (HFDRs), suggesting a genetic influence for this humoral response. In mice, anti-glucan antibody response depends on the NLRP3 inflammasome. Here, we explored the effect of mutated CARD8, a component of the inflammasome, on anti-glycans antibody response in human. METHODS: The association between p.C10X mutation (rs2043211) of the CARD8 gene and the levels of anti-glycans antibody response was examined in 39 CD families. The family-based QTDT association test was used to test for the genetic association between CARD8 p.C10X mutation and anti-glycan antibodies in the pedigrees. The difference in antibody responses determined by ELISA was tested in a subgroup of CD probands (one per family) and in a subgroup of HFDRs using the Wilcoxon Kruskal Wallis non-parametric test. RESULTS: The QTDT familial transmission tests showed that the p.C10X mutation of CARD8 was significantly associated with lower levels of antibody to mannans and glucans but not chitin (p=0.024, p=0.0028 and p=0.577, for ASCA, ALCA and ACCA, respectively). These associations were independent of NOD2 and NOD1 genetic backgrounds. The p.C10X mutation significantly associated or displayed a trend toward lower ASCA and ALCA levels (p=0.038 and p=0.08, respectively) only in the subgroup of CD probands. Such associations were not significant for ACCA levels in both subgroups of CD probands and of HFDRs. CONCLUSION: Our results show that ASCA and ALCA but not ACCA levels are under the influence of CARD8 genotype. Alteration of CARD8, a component of inflammasome, is associated with lower levels of antibodies directed to mannans and glucans at least in CD patients.

Murine model of dextran sulfate sodium-induced colitis reveals Candida glabrata virulence and contribution of ß-mannosyltransferases.

Candida glabrata, like Candida albicans, is an opportunistic yeast pathogen that has adapted to colonize all segments of the human gastrointestinal tract and vagina. The C. albicans cell wall expresses ß-1,2-linked mannosides (ß-Mans), promoting its adherence to host cells and tissues. Because ß-Mans are also present in C. glabrata, their role in C. glabrata colonization and virulence was investigated in a murine model of dextran sulfate sodium (DSS)-induced colitis. Five clustered genes of C. glabrata encoding ß-mannosyltransferases, BMT2-BMT6, were deleted simultaneously. ß-Man expression was studied by Western blotting, flow cytometry, and NMR analysis. Mortality, clinical, histologic, and colonization scores were determined in mice receiving DSS and different C. glabrata strains. The results show that C. glabrata bmt2-6 strains had a significant reduction in ß-1,2-Man expression and a disappearance of ß-1,2-mannobiose in the acid-stable domain. A single gavage of C. glabrata wild-type strain in mice with DSS-induced colitis caused a loss of body weight, colonic inflammation, and mortality. Mice receiving C. glabrata bmt2-6 mutant strains had normal body weight and reduced colonic inflammation. Lower numbers of colonies of C. glabrata bmt2-6 were recovered from stools and different parts of the gastrointestinal tract. Histopathologic examination revealed that the wild-type strain had a greater ability to colonize tissue and cause tissue damage. These results showed that C. glabrata has a high pathogenic potential in DSS-induced colitis, where ß-Mans contribute to colonization and virulence.

In vitro pro- and anti-inflammatory responses to viable Candida albicans yeasts by a murine macrophage cell line.

The balance between pro- and anti-inflammatory cytokine production is a crucial aspect of infections caused by Candida albicans. We therefore investigated the effect of yeast concentration on the pro- and anti-inflammatory cytokine response. Production of tumor necrosis factor-alpha (TNF-α) by the murine macrophage cell line J774 decreased significantly as the live yeast concentration increased. In parallel, a dose-dependent production of interleukin-10 (IL-10) was observed with live C. albicans. Paraformaldehyde-treated yeasts were unable to stimulate or modulate this response. Yeast culture supernatants induced high levels of TNF-α production when added to the macrophage cells, but did not down-modulate the macrophage response. In contrast, supernatants from yeast-macrophage co-cultures stimulated less TNF-α production and induced a down-modulation of the macrophage response, showing that modulation depended on macrophage- or yeast-derived components secreted when the yeast concentration was high. Phospholipomannan (PLM), but not farnesol, stimulated TNF-α production, but neither PLM nor farnesol down-modulated cytokine production in response to yeasts. Yeast culture supernatants or supernatants from yeast-macrophage co-cultures did not induce IL-10 production. These results suggest that the final macrophage cytokine response is determined by the interplay between live yeasts and macrophages, and that the direction of the response is dependent on the yeast concentration.

Host responses to a versatile commensal: PAMPs and PRRs interplay leading to tolerance or infection by Candida albicans.

The molecular interactions between commensal microorganisms and their host are basically different from those triggered by pathogens since they involve tolerance. When the commensal is genetically equipped to become an opportunistic pathogen, as is the case with Candida albicans, the picture becomes more complex. In this case, the balance between protection and invasion depends on host reactivity to altered microbial expression of ligands interacting with innate immune sensors. Based on experimental evidence obtained with C. albicans, we discuss the different molecular processes involved in the sensing of this important opportunistic human pathogen by a panel of pattern recognition receptors (PRRs) according to the numerous pathogen-associated molecular patterns (PAMPs) that can be exposed at its surface. Beneficial or deleterious immune responses that either maintain a commensal state or favour damage by the yeast result from this dynamic interplay.

A method for examining glycans surface expression of yeasts by flow cytometry.

Recognition of pathogenic yeasts by host cells is based on components of the yeast cell wall, which are considered part of its virulence attributes. Cell wall glycans play an important role in the continuous interchange that regulates the balance between saprophytism and parasitism and between resistance and infection. Flow cytometry is a useful method for probing surface yeast glycans in order to compare their expression depending on strains and growth conditions. By using different monoclonal or polyclonal antibodies, levels of beta- and alpha-linked mannosides as well as beta-glucans can be successfully evaluated by flow cytometry methods. The cytometric method we describe here represents a useful tool to investigate to what extent yeasts are able to regulate their glycan surface expression and therefore modify their virulence properties.