Systemic neutrophils are triggered by respiratory Bacillus Calmette- Guérin and mediate pulmonary mycobacterial clearance in synergy with the triggering receptor expressed on myeloid cells 1.

Tuberculosis remains a threat to public health. The only approved vaccine, Bacillus Calmette-Guérin (BCG), is administered intradermally and provides limited protection, and its effect on innate immunity via the respiratory route has not been fully elucidated. A mouse model with genetically depleted TREM1 and seven-color flow cytometry staining were used to characterize the comprehensive immune response induced by respiratory BCG, through evaluating organ bacterial loads, lung histopathology, and lung immunohistochemistry. During respiratory BCG infection, the murine lungs displayed effective bacterial clearance. Notably, marked differences in neutrophils were observed between thymus and bone marrow cells, characterized by a significant increase in the expression of the triggering receptor expressed on myeloid cells 1 (TREM1). Subsequently, upon depletion of TREM1, a reduction in pulmonary neutrophils was observed, which further exacerbated bacterial loads and resulted in worsened pathology following respiratory BCG infection. In summary, up-regulated expression of TREM1 in rapidly increasing circulating neutrophil by pulmonary BCG is required for an efficient host response to BCG infection, and suggests the important role of TREM1 in neutrophil-related pulmonary bacteria clearance and pathology.

Polymorphism of OAS2 rs739901 C/A Involves the Susceptibility to EV71 Infection in Chinese Children.

This study aimed to assess the relationship of OAS2 rs739901 5,-flanking C/A polymorphisms with the susceptibility to Enterovirus-71 (EV71) infection. We investigated 294 hand-foot-mouth disease (HFMD) Chinese children with EV71 infection (165 mild cases and 129 encephalitis cases). The improved multiplex ligation detection reaction (iMLDR) technique was used to test the genotypes. In EV71-infected patients, the CA genotype distribution (P=0.007), A allele frequency (OR 1.32,95% CI 1.0-1.7, P=0.034) and CA+AA carriage frequency (P=0.003) of OAS2 rs739901 5'-flanking were obviously elevated as compared with controls, but there were no statistically significant differences between mild cases and encephalitis cases. In EV71-infected patients, the counts of white blood cells (P=0.034) and blood glucose concentrations (P=0.042) were raised in A carriers (CA+AA). Among different genotypes of encephalitis cases, the contents of cerebrospinal fluid (CSF) showed no significant differences. IFN-γ levels in EV71-infected patients were higher than those in controls (mild group vs. control group, P<0.01; encephalitis group vs. control group, P<0.01;). In encephalitis cases, IFN-γ levels were reduced (P<0.05) in A carriers compared to CC genotype, however, there were no significant differences between genotypes CA and AA (P=0.226). These findings suggest that OAS2 rs739901 5'-flanking C/A genetic polymorphisms involve the susceptibility to EV71 infection, and A allele might be a risk factor of the susceptibility to EV-71 infection.