INFLAMMATORY RESPONSES AT THE BOUNDARY BETWEEN THE HOST AND THE WORLD BEYOND: THE DILEMMA OF INFECTION VERSUS COLONIZATION FROM A TONSILLAR PERSPECTIVE

SARMIENTO VARÓN L; DE ROSA J; FERNANDEZ PABLO; ARABOLAZA ME; PAOLI BP; VAY C; BARBERIS CM; ARANA EI

Buenos Aires

Congreso; LXVIII REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE INMUNOLOGÍA (SAI); 2020

Obstructive sleep apnoea (OSAS) is a syndrome suffered by childrenwith hypertrophied tonsils. We have previously demonstratedthat these tonsils present a defective Breg compartment. Here,we extend those findings by evidencing the inflammatory cytokinepattern of tonsillar mononuclear cells (TMC) and investigating thegrounds of such profile. OSAS TMC were the only cells used for thiswork. We showed the ability of Bcs to promote the loss of immunehomeostatic control by promptly producing TNFα. Using FACS, wedetermined TNFα production by stimulated TMC in culture. Upon 24hours, Bcs represented the majority of TNFα+ cells (52,4% ± SEM4,2% CD20+/down cells vs 41,7% ± SEM 4,0% CD3+ cells, p < 0.05).Conversely, at the same time point, IL17 was produced primarily byCD4+ T cells (Th17) which comprised 90% of the IL17+ population.Also at 24 hs post stimulation, two thirds of the Th17 population(59% ± SEM 4%) co-expressed TNFα. Despite the pro-inflammatoryprofile displayed by TMC in culture, OSAS has long been consideredof non-infectious etiology. We cultured the core tonsillar tissueof 31 children and identified 89 bacterial species by MALDI-TOFMS. The species identified had been previously found either causingENT pathology or as harmless local flora, both situations in competenthosts. Pathogens differ from commensals in being able topenetrate the epithelial barriers. Hence, we performed fluorescencein situ hybridization (FISH) with a universal eubacterial (EUB338)probe followed by immune-fluorescence staining, on cryo-sectionsfrom excised tonsils. By confocal microscopy, we confirmed bacterialpresence within the lymphoid compartment from OSAS biopsies.To conclude, while we cannot ascertain that the microorganisms detectedin situ as well as through culture are the initiators of the ongoinginflammatory response characteristic of OSAS, the chronificationof the process must be related to the evidenced bacterial spreadingbeyond the normal boundaries.