IgA in human health and diseases: Potential regulator of commensal microbiota

Abstract

Gut microbiota has extensive and tremendous impacts on human physiology and pathology. The regulation of microbiota is therefore a cardinal problem for the mutualistic relationship, as both microbial overgrowth and excessive immune reactions toward them could potentially be detrimental to host homeostasis. Growing evidence suggests that IgA, the most dominant secretory immunoglobulin in the intestine, regulates the colonization of commensal microbiota, and consequently, the microbiota-mediated intestinal and extra-intestinal diseases. In this review, we discuss the interactions between IgA and gut microbiota particularly relevant to human pathophysiology. We review current knowledge about how IgA regulates gut microbiota in humans and about the molecular mechanisms behind this interaction. We further discuss the potential role of IgA in regulating human diseases by extrapolating experimental findings, suggesting that IgA can be a future therapeutic strategy that functionally modulates gut microbiota.

Functional effects of yacon (Smallanthus sonchifolius) and kefir on systemic inflammation, antioxidant activity, and intestinal microbiome in rats with induced colorectal cancer

“…Thus, despite the greater production of IgA being beneficial for the organism, the non-stimulation of additional production does not cause major harm either. 60 Thus, it turns out that since the cancer did not alter the production of IgA, the diets with yacon and kefir maintained the levels of this immunoglobulin within normal limits, even similar to the healthy group, without having additional effects on it. In other studies the beneficial effects of yacon on the immunological status of mice 36 have been observed and yacon consumption increased the fecal IgA levels in CRC-induced rats.…”

Serological assays to measure dimeric IgA antibodies in SARS‐CoV‐2 infections

“…Other mechanisms that could be contributing to dIgA levels for such an extended period include liver disease, microbial dysbiosis and intestinal disease. [10][11][12][13][14] Within the Biomex cohort, the ELISA levels of dIgA and IgA are similar across four individuals, whereas the MBA shows a clear differentiation in the levels of dIgA and IgA. Overall, the MBA had slightly better resolution between dIgA and IgA responses and allowed simultaneous detection of IgG, IgA and dIgA within the same reaction, making it amenable to high-throughput screening on samples where only small volumes are available.…”

“…Alternatively, severe COVID‐19 infection may impair transcytosis of dIgA across mucosal surfaces resulting in an accumulation of dIgA in blood, and lack of SIgA at the mucosa, which could in turn impair viral clearance, contributing to severe COVID‐19. Other mechanisms that could be contributing to dIgA levels for such an extended period include liver disease, microbial dysbiosis and intestinal disease 10–14 …”

Requirement of a Wnt5A-Microbiota Axis in the Maintenance of Gut B Cell Repertoire and Protection from Infection

“…Alongside, we measured bacteria bound IgA in the PP of all sets of mice in line with its strong correlation with alteration of microbial abundance and dysbiosis, as well as prevalence of gut infection (4,(14)(15)(16)(17)(18)(19). Experiments performed in the steady state revealed significantly higher level of bacteria bound secreted IgA (sIgA) but similar percentages of IgM and IgA expressing B220+, B1a and B1b cells in the PP of the Wnt5A heterozygous mice as compared to the wild type counterparts (Figures 1A, 1B and 1C).…”