The variegated aspects of Immunoglobulin A

Serum immunoglobulin A levels: Diagnostic utility in alcoholic liver disease and association with liver fibrosis in steatotic liver disease

The relationship between immunoglobulin A (IgA) levels and chronic liver disease remains poorly understood. The present study evaluated the clinical significance of IgA in 478 new patients who visited the Outpatient Clinic of Nagasaki Harbor Medical Center (Nagasaki, Japan). Serum IgA levels in comparison to liver stiffness (LS), as measured using a FibroScan® device, were evaluated in 358 patients. Furthermore, in 270 patients, the associations between serum IgA levels and body composition were analyzed using computed tomography. The IgA levels of patients in the groups with Child-Pugh classification B and C (CPGBC), alcoholic liver disease (ALD), steatotic liver disease (SLD) or diabetes were higher than the IgA levels of patients in the groups with CPGA, non-ALD, non-SLD or no diabetes, respectively. Logistic regression analysis showed that CPGBC, ALD, high IgG (>1,700 mg/dl), high macrophage galactose-specific lectin-2 binding protein glycosylation isomer (M2BPGi) (>1 cut-off index) and diabetes were contributing factors for high serum IgA level (>410 mg/dl). The ratio of IgA level divided by IgG level was highest in patients with ALD, followed by those with metabolic dysfunction-associated SLD (MASLD) and non-SLD. In SLD, IgA level was associated more with LS than M2BPGi and fibrosis-4 (FIB-4) in multiple regression analysis. In the receiver operating characteristic analysis, IgA level, M2BPG, and FIB-4 had similar area under the curve values for discriminating high LS (>8 kPa) from low LS (≤8 kPa) in SLD. IgA levels were also associated with visceral fat, and this association was only found in women. In conclusion, elevated IgA is an indicator of liver fibrosis that also reflects the presence of diabetes and an increased visceral fat level. Therefore, IgA is considered a useful marker of liver disease severity in the current era of increased SLD.

Mucosal delivery of Lactococcus lactis carrying an anti-TNF scFv expression vector ameliorates experimental colitis in mice

Background

Anti-Tumor Necrosis Factor-alpha therapy has become clinically important for treating inflammatory bowel disease. However, the use of conventional immunotherapy requires a systemic exposure of patients and collateral side effects. Lactic acid bacteria have been shown to be effective as mucosal delivering system for cytokine and single domain antibodies, and it is amenable to clinical purposes. Therefore, lactic acid bacteria may function as vehicles for delivery of therapeutic antibodies molecules to the gastrointestinal tract restricting the pharmacological effect towards the gut. Here, we use the mucosal delivery of Lactococcus lactis carrying an anti-TNFα scFv expression plasmid on a DSS-induced colitis model in mice.

Results

Experimental colitis was induced with DSS administered in drinking water. L. lactis carrying the scFv expression vector was introduced by gavage. After four days of treatment, animals showed a significant improvement in histological score and disease activity index compared to those of untreated animals. Moreover, treated mice display IL-6, IL17A, IL1β, IL10 and FOXP3 mRNA levels similar to health control mice. Therefore, morphological and molecular markers suggest amelioration of the experimentally induced colitis.

Conclusion

These results provide evidence for the use of this alternative system for delivering therapeutic biopharmaceuticals in loco for treating inflammatory bowel disease, paving the way for a novel low-cost and site-specific biotechnological route for the treatment of inflammatory disorders.

Electronic supplementary material

The online version of this article (10.1186/s12896-019-0518-6) contains supplementary material, which is available to authorized users.

Protective Microbiota: From Localized to Long-Reaching Co-Immunity

Resident microbiota do not just shape host immunity, they can also contribute to host protection against pathogens and infectious diseases. Previous reviews of the protective roles of the microbiota have focused exclusively on colonization resistance localized within a microenvironment. This review shows that the protection against pathogens also involves the mitigation of pathogenic impact without eliminating the pathogens (i.e., “disease tolerance”) and the containment of microorganisms to prevent pathogenic spread. Protective microorganisms can have an impact beyond their niche, interfering with the entry, establishment, growth, and spread of pathogenic microorganisms. More fundamentally, we propose a series of conceptual clarifications in support of the idea of a “co-immunity,” where an organism is protected by both its own immune system and components of its microbiota.

The regulation of gut mucosal IgA B-cell responses: recent developments

The majority of activated B cells differentiate into IgA plasma cells, with the gut being the largest producer of immunoglobulin in the body. Secretory IgA antibodies have numerous critical functions of which protection against infections and the role for establishing a healthy microbiota appear most important. Expanding our knowledge of the regulation of IgA B-cell responses and how effective mucosal vaccines can be designed are of critical importance. Here we discuss recent developments in the field that shed light on the uniqueness and complexity of mucosal IgA responses and the control of protective IgA responses in the gut, specifically.

Cross-talk between microbiota and immune fitness to steer and control response to anti PD-1/PDL-1 treatment

Immune Checkpoint Inhibitors (ICIs) are improving the survival of cancer patients, however only the 20-30% of treated patients present clinical benefits. Toxicity represents the major cause of reduced dosage, delayed drug administration and therapy discontinuation. Hence in the context of multiple treatment possibilities, the identification of predictive markers of response and toxicity is a challenging approach for drug selection in order to obtain the best clinical benefit while minimizing the side effects. The loss of the protective function of intestinal barriers that interacts with the environment measured as increased intestinal permeability and the changes occurring in the microbiota composition have been proposed as a mechanism potentially explaining the pathogenesis of immune related toxicity.In this review we discuss the new perspectives on the involvement of PD-1 and PDL-1 in the cross talk between gut microbiota and immune fitness and how gut microbiota impacts on the efficacy of anti-PD-1 and anti-PDL-1 treatments in cancer.