Dendritic cell activation by sensing Mycobacterium tuberculosis-induced apoptotic neutrophils via DC-SIGN

• In Mycobacterium tuberculosis (Mtb)-infected individuals cells of the innate immune system accumulate in the spleen and in granulomas, but how this relates to the protection against Mtb or in the pathogenesis is unknown. Mtb is internalized in the lung by phagocytic cells, such as neutrophils (PMNs), dendritic cells (DCs) and macrophages. PMNs undergo accelerated apoptosis after internalization of the bacterium and are subsequently sequestered by neighbouring phagocytes. Removal of aged apoptotic cells is an immunologically silent process and the aim of this study was to clarify the interaction between Mtb-induced apoptotic PMNs and DCs, and evaluate if this interaction induced functional maturation of the DCs. In fact,  Mtb-induced apoptotic PMNs induced DC maturation, whereas exposure to spontaneous apoptotic PMNs had no effect on DCs maturation status. We found that the cell fraction contained almost all stimulatory capacity, suggesting that the cell-cell interaction is crucial for DC activation. Inhibitory studies showed that this cell contact-dependent activation required binding of the PMN Mac-1 (CD11b/CD18) to the DC via DC-SIGN and endocytic activity. Taken together, this study proves that the DCs can distinguish between normal and infected apoptotic PMNs via cellular cross talk, where the DCs can sense the presence of danger on the Mtb-infected PMNs and modulate their response accordingly.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Mikrobiologi inom det medicinska området (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Microbiology in the medical area (hsv//eng)

Keyword

Microbiology, immunology, infectious diseases

Mikrobiologi, immunologi, infektionssjukdomar

Publication and Content Type

vet (subject category)

ovr (subject category)