Live L. casei can counteract the proinflammatory effects of E. coli on CD inflamed mucosa by specific downregulation of key proinflammatory mediators.

(Gut 1998;42:643-649)

Apoptosis of active T lymphocytes constitutes a major control mechanism of immune homeostasis and tolerance. In Crohn's disease, abnormal activation of mucosal T lymphocytes against enteric bacteria is the key event triggering intestinal inflammation. Resistance of lymphocytes to apoptosis has been proposed as the pathogenetic defect. We examined the influence of bacteria-mucosa interactions on apoptosis of mucosal T lymphocytes. Ileal specimens were obtained at surgery from 12 patients with Crohn's disease. Mucosal explants from each specimen were cultured with nonpathogenic Escherichia coli ATCC 35345, Lactobacillus casei DN-114 001, or no bacteria. Cytokine release was measured in supernatant, and mononuclear cells were isolated for phenotypic characterization and Bcl-2 family protein expression. Coculture of inflamed tissue with L. casei significantly reduced the release of interleukin (IL)-6 and tumor necrosis factor alpha (P < 0.05). In addition, coculture with L. casei significantly reduced the number of T cells displaying the IL-2 receptor in the lamina propria. Expression of the antiapoptotic protein Bcl-2 in lamina propria lymphocytes was also reduced after coculture with L. casei, and the percentage of deoxyuridine triphosphate nick-end labeling positive lymphocytes increased. The nonpathogenic E. coli strain had no significant effect. In conclusion, L. casei reduces the number of activated T lymphocytes in the lamina propria of Crohn's disease mucosa. A balanced, local microecology may restore immune homeostasis.

Background Before the COVID-19 pandemic, Sexually transmitted infections (STIs) were increasing in Europe, and Spain and Catalonia were not an exception. Catalonia has been one of the regions with the highest number of COVID-19 confirmed cases in Spain. The objective of this study was to estimate the magnitude of the decline, due to the COVID-19 pandemic, in the number of STI confirmed cases in Catalonia during the lockdown and de-escalation phases. Methods Interrupted time series analysis was performed to estimate the magnitude of decline in the number of STI reported confirmed cases - chlamydia, gonorrhoea, syphilis, and lymphogranuloma venereum- in Catalonia since lockdown with historical data, from March 13th to August 1st 2020, comparing the observed with the expected values. Results We found that since the start of COVID-19 pandemic the number of STI reported cases was 51% less than expected, reaching an average of 56% during lockdown (50% and 45% during de-escalation and new normality) with a maximum decrease of 72% for chlamydia and minimum of 22% for syphilis. Our results indicate that fewer STIs were reported in females, people living in more deprived areas, people with no previous STI episodes during the last three years, and in the HIV negative. Conclusions The STI notification sharp decline was maintained almost five months after lockdown started, well into the new normality. This fact can hardly be explained without significant underdiagnosis and underreporting. There is an urgent need to strengthen STI/HIV diagnostic programs and services, as well as surveillance, as the pandemic could be concealing the real size of the already described re-emergence of STIs in most of the European countries.