A Direct MS-Based Approach to Profile Human Milk Secretory Immunoglobulin A (IgA1) Reveals Donor-Specific Clonal Repertoires With High Longitudinal Stability

Recently, a mass spectrometry-based approach was introduced to directly assess the IgG1 immunoglobulin clonal repertoires in plasma. Here we expanded upon this approach by describing a mass spectrometry-based technique to assess specifically the clonal repertoire of another important class of immunoglobulin molecules, IgA1, and show it is efficiently and robustly applicable to either milk or plasma samples. Focusing on two individual healthy donors, whose milk was sampled longitudinally during the first 16 weeks of lactation, we demonstrate that the total repertoire of milk sIgA1 is dominated by only 50-500 clones, even though the human body theoretically can generate several orders of magnitude more clones. We show that in each donor the sIgA1 repertoire only changes marginally and quite gradually over the monitored 16-week period of lactation. Furthermore, the observed overlap in clonal repertoires between the two individual donors is close to non-existent. Mothers provide protection to their newborn infants directly by the transfer of antibodies via breastfeeding. The approach introduced here, can be used to visualize the clonal repertoire transferred from mother to infant and to detect changes in-time in that repertoire adapting to changes in maternal physiology.

Induced Polyspecificity of Human Secretory Immunoglobulin A Antibodies: Is It Possible to Improve Their Ability to Bind Pathogens?

<b><i>Introduction:</i></b> As has been shown previously, various protein-modifying agents can change the antigen-binding properties of immunoglobulins. However, induced polyspecificity of human secretory immunoglobulin A (sIgA) has not been previously characterized in detail. <b><i>Methods:</i></b> In the present study, human secretory immunoglobulin A (IgA) was exposed to buffers with acidic pH, to free heme, or to pro-oxidative ferrous ions, and the antigen-binding behavior of the native and modified IgA to viral and bacterial antigens was compared using Western blotting and enzyme-linked immunosorbent assay. The ability of these agents to modulate the antigen-binding properties of human sIgA toward a wide range of pathogen peptides was investigated using an epitope microarray. <b><i>Results:</i></b> We have shown that acidic pH, heme, and pro-oxidative ferrous ions influenced the binding of secretory IgA in opposite directions (either increasing or decreasing); however, the strongest effect was observed when using buffers with low pH. This fraction had the highest number of affected reactivities; most of them were increased and most of the new ones were toward common pathogens. <b><i>Conclusions:</i></b> Thus, it was shown that all investigated treatments can alter to some degree the antigen-binding of secretory IgA, but acidic pH has the most potentially beneficial effect by increasing binding to a largest number of common pathogens’ antigens.

The immune landscape of IgA induction in the gut

Antibodies are key elements of protective immunity. In the mucosal immune system in particular, secretory immunoglobulin A (SIgA), the most abundantly produced antibody isotype, protects against infections, shields the mucosal surface from toxins and environmental factors, and regulates immune homeostasis and a peaceful coexistence with our microbiota. However, the dark side of IgA biology promotes the formation of immune complexes and provokes pathologies, e.g., IgA nephropathy (IgAN). The precise mechanisms of how IgA responses become deregulated and pathogenic in IgAN remain unresolved. Yet, as the field of microbiota research moved into the limelight, our basic understanding of IgA biology has been taking a leap forward. Here, we discuss the structure of IgA, the anatomical and cellular foundation of mucosal antibody responses, and current concepts of how we envision the interaction of SIgA and the microbiota. We center on key concepts in the field while taking account of both historic findings and exciting new observations to provide a comprehensive groundwork for the understanding of IgA biology from the perspective of a mucosal immunologist.

Secretory immune status of oral cavity in the patients with Сandida-associated denture stomatitis

Age-related changes in the oral mucosa immunity, including decreased contents of secretory immunoglobulins and antimicrobial peptides in saliva, along with changed balance of pro- and antiinflammatory cytokines, care risks for development of purulent-inflammatory or allergic diseases of the oral cavity. For example, denture stomatitis (DS) caused by Candida albicans occurs in about 30—70% of denture users. The purpose of this study was to assess the secretory immune state of oral mucous membranes in the patients with Candida-associated denture stomatitis. We examined 42 elderly patients (61-72 years old) with one-piece acrylic dentures for at least, 6 months (15 men and 27 women). Based on clinical and microbiological studies, the patients were divided into a group with DS (n = 24) and a group without DS (n = 18). The contents of secretory immunoglobulin A (sIgA) and proinflammatory cytokines was determined, i.e., interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), tumor necrosis factor-α (TNFα), and anti-inflammatory cytokines, e.g., receptor antagonist of interleukin-1 (RAIL), interleukin-4 (IL-4), interleukin-10 (IL-10), as well as antimicrobial peptides (cathelicidin LL-37, lactoferrin and alphadefensins 1-3 (HNP1-3). The sIgA levels in the salivary fluid of patients with DS (0.92 (0.80-1.26) g/l) were significantly lower (p < 0.05) than in patients without stomatitis (1.71 (1.23-2,13) g/l). In the group with advanced DS, a significant increase of IL-1β levels in saliva was observed, along with simultaneous decrease of IL-8 concentrations, compared to the other group, without differences in TNFα and IL-6 concentrations. Increased contents of IL-10 in saliva was also noted. It was shown that the concentrations of cathelicidin LL-37 in saliva of the DS patients was increased two-fold, whereas the contents of neutrophil-derived alpha-defensins (HNP 1-3) was decreased. Conclusions: The development of inflammation in denture stomatitis caused by usage of removable acrylic dentures associated with Candida albicans infection is characterized by functional insufficiency of the secretory immunity of the oral mucosa associated with decreased amounts of secretory immunoglobulin A and antimicrobial peptides of neutrophilic origin. Low levels of alpha-defensins may suggest a decrease in the functional activity of neutrophils in the elderly, thus leading to higher susceptibility to fungal infection of oral cavity.

Immunodiagnostics, immunotherapy and immunoprophylaxis in otorhinolaryngological practice. Report 3. Diagnostic approaches to the palatine tonsils functional state assessment for selecting a treatment strategy for patients with chronic tonsillitis (analytical summary)

Experimental work carried out over the past 20 years to study the activity of various functional groups in tonsillar cells in patients with chronic tonsillitis (CT) under local exposure to various immune response modifiers showed that: - tonsillar cells from CT patients in 69.5% of cases are capable of increasing their immunofunctional activity under the influence of immune modifiers in vitro reactions; - the most active of the group of immunotropic immune response modifiers are T-activin and Thymogen; - it can be considered the optimal diagnostic technique to carry out a "stress" test on the tonsil tissue using nonspecific (alternating magnetic field of industrial (low) frequency and low-frequency ultrasound) and specific — a microbial vaccine when applied to the tonsil tissue; - a non-invasive method for recording changes in the tonsils after stimulation may be fluctuations in the level of secretory immunoglobulin A and α-interferon in saliva after the test; - an increase in the level of secretory immunoglobulin A and α-interferon by more than 1/3 of the initial level after the test is a clinically favorable sign and a recommendation for medical treatment to the managing of patients with CT.