Differential stimulation of peripheral blood mononuclear cells in Crohn's disease by fungal glycans

Mannan activates tissue native and IgE-sensitized mast cells to proinflammatory response and chemotaxis in TLR4-dependent manner

Mast cells take part in host defense against microorganisms as they are numerous at the portal of infection, exert several essential mechanisms of pathogen destruction, and they express pattern recognition receptors. Accumulating evidence indicates that these cells are involved in the control and clearance of bacterial, viral, or parasitic infections, but much less is known about their contribution in defense against fungi. The study was aimed to establish whether mannan, which comprises an outermost layer and major structural constituent of the fungal cell wall, may directly stimulate tissue mast cells to the antifungal response. Our findings indicate that mannan activates mast cells isolated from the rat peritoneal cavity to initiate the proinflammatory response. We found that mannan stimulates mast cells to release histamine and to generate cysteinyl leukotrienes, cytokines (IFN-γ, GM-CSF, TNF), and chemokines (CCL2, CCL3). It also increased the mRNA expression of various cytokines/chemokines. We also documented that mannan strongly activates mast cells to generate reactive oxygen species and serves as a potent chemoattractant for these cells. Furthermore, we established that mannan-induced activity of mast cells is mediated via TLR4 with the involvement of the spleen tyrosine kinase molecule. Taking together, our results clearly support the idea that mast cells act as sentinel cells and crucially determine the course of the immune response during fungal infection. Additionally, presented data on IgE-coated mast cells suggest that exposure to fungal mannan could influence the severity of IgE-dependent diseases, including allergic ones.

Commensal fungi and their cell-wall β-glucans direct differential responses in human intestinal epithelial cells

Intestinal epithelial cells (IECs) are the first to encounter luminal antigens and play an active role in intestinal immune responses. We previously reported that β-glucans, major fungal cell-wall glycans, induced chemokine secretion by IEC lines in a Dectin-1- and Syk-dependent manner. Here, we show that in contrast to β-glucans, stimulation of IEC lines with Candida albicans and Saccharomyces cerevisiae did not induce secretion of any of the proinflammatory cytokines IL-8, CCL2, CXCL1, and GM-CSF. Commensal fungi and β-glucans activated Syk and ERK in IEC lines. However, only β-glucans activated p38, JNK, and the transcription factors NF-κB p65 and c-JUN, which were necessary for cytokine secretion. Furthermore, costimulation of IEC lines with β-glucans and C. albicans yielded decreased cytokine secretion compared to stimulation with β-glucans alone. Finally, ex vivo stimulation of human colonic mucosal explants with zymosan and C. albicans, leads to epithelial Syk and ERK phosphorylation, implying recognition of fungi and similar initial signaling pathways as in IEC lines. Lack of cytokine secretion in response to commensal fungi may reflect IECs' response to fungal glycans, other than β-glucans, that contribute to mucosal tolerance. Skewed epithelial response to commensal fungi may impair homeostasis and contribute to intestinal inflammation.

The association between Candida infection and ankylosing spondylitis: a population-based matched cohort study

AIMS

To explore whether newly diagnosed Candida infection increases the risk of developing ankylosing spondylitis (AS).

METHODS AND MATERIALS

We investigated 61,550 patients with newly diagnosed Candida infection between 1997 and 2013 from the Taiwan National Health Insurance Research Datasets to conduct a population-based matched-cohort study. Controls were 61,550 subjects without Candida infection and propensity score matched with the Candida exposure cohort. The follow-up period was defined as month from the initial diagnosis of Candida infection (or nested index date for controls) to the date of AS, or 31 December 2013. We used Cox proportional hazards models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the occurrence of AS.

RESULTS

The incidence rates of AS in the Candida group and comparison group were respectively 4.58 and 3.88 per 100,000 person-months. The adjusted HR (95% CI) of AS for the Candida group was 1.19 (0.99-1.44) compared to the control group after adjustment for age, gender and all covariates (95% CI = 1.77-2.27). However, an adjusted hazard ratio (aHR) of 1.77-fold (95% CI = 1.26-2.53) significant increase in the risk of developing AS was observed after 6 years of follow-up, when exposure to Candida was at baseline. The effect of Candida infection was significantly time varying (p value for interaction between follow-up period and Candida infection is .018).

CONCLUSIONS

A risk of AS was found after Candida infection, and a year of follow-up acts as an effect modifier between the Candida infection and risk of AS. Key messages What is already known on this subject? Links between spondyloarthritis and fungal infections have been found in animal studies before. What does this study add? Our study demonstrated that Candida infection is an independent risk factor for developing ankylosing spondylitis in terms of gender, age and relevant variables and comorbidities. A risk of ankylosing spondylitis was found after Candida infection, and year of follow-up acts as an effect modifier between the Candida infection and risk of AS. Clinicians should be aware of possible Candida infection in managing patients with ankylosing spondylitis. Implications: Clinicians must pay greater attention to patients with newly diagnosed Candida infection. Specifically, they should conduct tests for ankylosing spondylitis. Further research is needed to examine if and how treatment of Candida infection alleviates symptoms of AS.

Unique repertoire of anti-carbohydrate antibodies in individual human serum

Humoral immunity to pathogens and other environmental challenges is paramount to maintain normal health, and individuals lacking or unable to make antibodies are at risk. Recent studies indicate that many human protective antibodies are against carbohydrate antigens; however, little is known about repertoires and individual variation of anti-carbohydrate antibodies in healthy individuals. Here we analyzed anti-carbohydrate antibody repertoires (ACARs) of 105 healthy individual adult donors, aged 20-60+ from different ethnic backgrounds to explore variations in antibodies, as defined by binding to glycan microarrays and by affinity purification. Using microarrays that contained > 1,000 glycans, including antigens from animal cells and microbes, we profiled the IgG and IgM ACARs from all donors. Each donor expressed many ACAs, but had a relatively unique ACAR, which included unanticipated antibodies to carbohydrate antigens not well studied, such as chitin oligosaccharides, Forssman-related antigens, globo-type antigens, and bacterial glycans. We also saw some expected antibodies to ABO(H) blood group and α-Gal-type antigens, although these also varied among individuals. Analysis suggests differences in ACARs are associated with ethnicity and age. Thus, each individual ACAR is relatively unique, suggesting that individualized information could be useful in precision medicine for predicting and monitoring immune health and resistance to disease.

Detection of Beta-Glucan Contamination in Nanotechnology-Based Formulations

Understanding the potential contamination of pharmaceutical products with innate immunity modulating impurities (IIMIs) is essential for establishing their safety profiles. IIMIs are a large family of molecules with diverse compositions and structures that contribute to the immune-mediated adverse effects (IMAE) of drug products. Pyrogenicity (the ability to induce fever) and activation of innate immune responses underlying both acute toxicities (e.g., anaphylactoid reactions or pseudoallergy, cytokine storm) and long-term effects (e.g., immunogenicity) are among the IMAE commonly related to IIMI contamination. Endotoxins of gram-negative bacteria are the best-studied IIMIs in that both methodologies for and pitfalls in their detection and quantification are well established. Additionally, regulatory guidance documents and research papers from laboratories worldwide are available on endotoxins. However, less information is currently known about other IIMIs. Herein, we focus on one such IIMI, namely, beta-glucans, and review literature and discuss the experience of the Nanotechnology Characterization Lab (NCL) with the detection of beta-glucans in nanotechnology-based drug products.

Chitosan Nanoparticles: Shedding Light on Immunotoxicity and Hemocompatibility

Nanoparticles (NPs) assumed an important role in the area of drug delivery. Despite the number of studies including NPs are growing over the last years, their side effects on the immune system are often ignored or omitted. One of the most studied polymers in the nano based drug delivery system field is chitosan (Chit). In the scientific literature, although the physicochemical properties [molecular weight (MW) or deacetylation degree (DDA)] of the chitosan, endotoxin contamination and appropriate testing controls are rarely reported, they can strongly influence immunotoxicity results. The present work aimed to study the immunotoxicity of NPs produced with different DDA and MW Chit polymers and to benchmark it against the polymer itself. Chit NPs were prepared based on the ionic gelation of Chit with sodium tripolyphosphate (TPP). This method allowed the production of two different NPs: Chit 80% NPs (80% DDA) and Chit 93% NPs (93% DDA). In general, we found greater reduction in cell viability induced by Chit NPs than the respective Chit polymers when tested in vitro using human peripheral blood monocytes (PBMCs) or RAW 264.7 cell line. In addition, Chit 80% NPs were more cytotoxic for PBMCs, increased reactive oxygen species (ROS) production (above 156 μg/mL) in the RAW 264.7 cell line and interfered with the intrinsic pathway of coagulation (at 1 mg/mL) when compared to Chit 93% NPs. On the other hand, only Chit 93% NPs induced platelet aggregation (at 2 mg/mL). Although Chit NPs and Chit polymers did not stimulate the nitric oxide (NO) production in RAW 264.7 cells, they induced a decrease in lipopolysaccharide (LPS)-induced NO production at all tested concentrations. None of Chit NPs and polymers caused hemolysis, nor induced PBMCs to secrete TNF-α and IL-6 cytokines. From the obtained results we concluded that the DDA of the Chit polymer and the size of Chit NPs influence the in vitro immunotoxicity results. As the NPs are more cytotoxic than the corresponding polymers, one should be careful in the extrapolation of trends from the polymer to the NPs, and in the comparisons among delivery systems prepared with different DDA chitosans.

An increase in LRRK2 suppresses autophagy and enhances Dectin-1-induced immunity in a mouse model of colitis

The LRRK2/MUC19 gene region constitutes a high-risk genetic locus for the occurrence of both inflammatory bowel diseases (IBDs) and Parkinson's disease. We show that dendritic cells (DCs) from patients with Crohn's disease (CD) and lymphoblastoid cell lines derived from patients without CD but bearing a high-risk allele (rs11564258) at this locus as heterozygotes exhibited increased LRRK2 expression in vitro. To investigate the immunological consequences of this increased LRRK2 expression, we conducted studies in transgenic mice overexpressing Lrrk2 and showed that these mice exhibited more severe colitis induced by dextran sodium sulfate (DSS) than did littermate control animals. This increase in colitis severity was associated with lamina propria DCs that showed increased Dectin-1-induced NF-κB activation and proinflammatory cytokine secretion. Colitis severity was driven by LRRK2 activation of NF-κB pathway components including the TAK1 complex and TRAF6. Next, we found that membrane-associated LRRK2 (in association with TAB2) caused inactivation of Beclin-1 and inhibition of autophagy. HCT116 colon epithelial cells lacking Beclin-1 exhibited increased LRRK2 expression compared to wild-type cells, suggesting that inhibition of autophagy potentially could augment LRRK2 proinflammatory signaling. We then showed that LRRK2 inhibitors decreased Dectin-1-induced TNF-α production by mouse DCs and ameliorated DSS-induced colitis, both in control and Lrrk2 transgenic animals. Finally, we demonstrated that LRRK2 inhibitors blocked TNF-α production by cultured DCs from patients with CD. Our findings suggest that normalization of LRRK2 activation could be a therapeutic approach for treating IBD, regardless of whether a LRRK2 risk allele is involved.

Starch Consumption May Modify Antiglycan Antibodies and Fecal Fungal Composition in Patients With Ileo-Anal Pouch

BACKGROUND

Inflammatory bowel diseases (IBDs) are characterized by serologic responses to glycans. Patients with ulcerative colitis (UC) after proctocolectomy with ileo-anal anastomosis (pouch surgery) may develop inflammation (pouchitis) that resembles Crohn's disease (CD). We hypothesized that patients' serologic responses were affected by their consumption of dietary sugars. This study analyzed the correlations between antiglycan antibody expression and dietary sugar consumption in patients with UC pouch and the evolution in antibody levels over time.

METHODS

Patients were followed prospectively for 2 consecutive visits. The following antiglycan carbohydrate antibodies were detected by enzyme-linked immunosorbent assay: antichitobioside (ACCA), antilaminaribioside (ALCA), antimannobioside (AMCA), and anti-Saccharomyces cerevisiae (ASCA) antibodies. Patients completed a food frequency questionnaire. The fungal community in patients' fecal samples was analyzed by sequencing the internal transcribed spacer 2 (ITS2) region of nuclear ribosomal DNA.

RESULTS

We included 75 UC pouch patients aged 45.2 ± 14 years who underwent pouch surgery 9.8 ± 6.7 years previously. Of these patients, 34.7% (n = 26) showed seropositivity for antiglycan antibodies. Starch consumption was significantly higher in patients with positive serologic responses (P = 0.05). Higher starch consumption was associated with higher AMCA and ACCA titers, which increased by 4.08% (0.8%-7.4%; P = 0.014) and 4.8% (0.7%-9.1%; P = 0.007), respectively, for each 10-g increase of dietary starch. The per-patient change in the relative abundance of Candida albicans in fecal samples correlated positively with changes in starch consumption (Spearman's r = 0.72; P = 0.012).

CONCLUSIONS

Starch consumption correlated with positive antiglycan serology (ACCA and AMCA), suggesting that increased dietary starch intake may promote a specific immune response in patients with IBD.

Spondyloarthritis, Acute Anterior Uveitis, and Fungi: Updating the Catterall-King Hypothesis

Spondyloarthritis is a common type of arthritis which affects mostly adults. It consists of idiopathic chronic inflammation of the spine, joints, eyes, skin, gut, and prostate. Inflammation is often asymptomatic, especially in the gut and prostate. The HLA-B*27 allele group, which presents intracellular peptides to CD8+ T cells, is by far the strongest risk factor for spondyloarthritis. The precise mechanisms and antigens remain unknown. In 1959, Catterall and King advanced a novel hypothesis explaining the etiology of spondyloarthritis: an as-yet-unrecognized sexually acquired microbe would be causing all spondyloarthritis types, including acute anterior uveitis. Recent studies suggest an unrecognized sexually acquired fungal infection may be involved in prostate cancer and perhaps multiple sclerosis. This warrants reanalyzing the Catterall-King hypothesis based on the current literature. In the last decade, many links between spondyloarthritis and fungal infections have been found. Antibodies against the fungal cell wall component mannan are elevated in spondyloarthritis. Functional polymorphisms in genes regulating the innate immune response against fungi have been associated with spondyloarthritis (CARD9 and IL23R). Psoriasis and inflammatory bowel disease, two common comorbidities of spondyloarthritis, are both strongly associated with fungi. Evidence reviewed here lends credence to the Catterall-King hypothesis and implicates a common fungal etiology in prostate cancer, benign prostatic hyperplasia, multiple sclerosis, psoriasis, inflammatory bowel disease, and spondyloarthritis. However, the evidence available at this time is insufficient to definitely confirm this hypothesis. Future studies investigating the microbiome in relation to these conditions should screen specimens for fungi in addition to bacteria. Future clinical studies of spondyloarthritis should consider antifungals which are effective in psoriasis and multiple sclerosis, such as dimethyl fumarate and nystatin.

The Syk Inhibitor Fostamatinib Decreases the Severity of Colonic Mucosal Damage in a Rodent Model of Colitis

BACKGROUND AND AIMS

Inflammatory bowel disease is a chronic inflammatory disease of the gastrointestinal system. In some cases, current medications used for inflammatory bowel disease may not be enough for remission, creating a need for more potent and reliable medications. There is no study showing the efficacy of fostamatinib, with proven effects on some inflammatory diseases, on ulcerative colitis. In our study we planned to research the efficacy of fostamatinib, a spleen tyrosine kinase inhibitor, on acetic acid-induced colitis.

METHODS

The study included 28 male Sprague-Dawley rats, randomly divided into control group, fostamatinib group, colitis group and fostamatinib + colitis group, each containing seven rats. Colitis induction was performed with 4% acetic acid. Colonic inflammation was assessed with disease activity index, macroscopic and histological damage scores, colonic myeloperoxidase, malondialdehyde and superoxide dismutase activity, and tumour necrosis factor alpha [TNFα], CD3, Syk, and phospho-Syk expression.

RESULTS

There was a significant difference between the colitis and control groups in terms of all parameters. The disease activity index, macroscopic and microscopic damage scores, immunohistochemical TNFα, CD3, Syk, and phospho-Syk expression, and tissue myeloperoxidase activity were found to be significantly lower in the colitis + fostamatinib group compared with the colitis group. There was no significant difference between the two groups in terms of myeloperoxidase and malondialdehyde activity.

CONCLUSIONS

Fostamatinib reduced the inflammatory damage in the experimental colitis. This effect may be due to suppression of TNFα, T-lymphocytes, and neutrophils in colonic mucosa via suppression of Syk. Fostamatinib may be an appropriate treatment alternative for ulcerative colitis. Further clinical studies are required to support this.