AUTHOR=Rodel Hylton E. , Ferreira Isabella A. T. M. , Ziegler Carly G. K. , Ganga Yashica , Bernstein Mallory , Hwa Shi-Hsia , Nargan Kievershen , Lustig Gila , Kaplan Gilla , Noursadeghi Mahdad , Shalek Alex K. , Steyn Adrie J. C. , Sigal Alex
TITLE=Aggregated Mycobacterium tuberculosis Enhances the Inflammatory Response
JOURNAL=Frontiers in Microbiology
VOLUME=12
YEAR=2021
URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.757134
DOI=10.3389/fmicb.2021.757134
ISSN=1664-302X
ABSTRACT=
Mycobacterium tuberculosis (Mtb) bacilli readily aggregate. We previously reported that Mtb aggregates lead to phagocyte death and subsequent efficient replication in the dead infected cells. Here, we examined the transcriptional response of human monocyte derived macrophages to phagocytosis of aggregated Mtb relative to phagocytosis of non-aggregated single or multiple bacilli. Infection with aggregated Mtb led to an early upregulation of pro-inflammatory associated genes and enhanced TNFα signaling via the NFκB pathway. These pathways were significantly more upregulated relative to infection with single or multiple non-aggregated bacilli per cell. Phagocytosis of aggregates led to a decreased phagosome acidification on a per bacillus basis and increased phagocyte cell death, which was not observed when Mtb aggregates were heat killed prior to phagocytosis. Mtb aggregates, observed in a granuloma from a patient, were found surrounding a lesion cavity. These observations suggest that TB aggregation may be a mechanism for pathogenesis. They raise the possibility that aggregated Mtb, if spread from individual to individual, could facilitate increased inflammation, Mtb growth, and macrophage cell death, potentially leading to active disease, cell necrosis, and additional cycles of transmission.