Mycobacterium tuberculosis (Mtb) is an intracellular pathogen that can infect and replicate in macrophages. Peptidoglycan (PGN) is a major component of the mycobacterial cell wall and is recognized by host pattern recognition receptors (PRRs). Many bacteria modulate and evade the immune defenses of their hosts through PGN deacetylation. Rv1096 was previously characterized as a PGN N-deacetylase gene in Mtb. However, the underlying mechanism by which Rv1096 regulates host immune defenses during macrophage infection remains unclear. In the present study, we investigated the role of Rv1096 in evading host immunity using a recombinant M. smegmatis expressing exogenous Rv1096 and Rv1096-deleted Mtb strain H37Rv mutant. We found that Rv1096 promoted intracellular bacillary survival and inhibited the inflammatory response in M. smegmatis- or Mtb-infected macrophages. The inhibition of mycobacteria-induced inflammatory response in macrophages was at least partially due to NF-κB and MAPK activation downstream of TLR and NOD signaling pathways. Furthermore, we found that Rv1096 inhibitory effect on inflammatory response was associated with TLR2, TLR4 and NOD2. Finally, we demonstrated the PGN deacetylase activity of Rv1096 by Fourier transform IR and Rv1096 NODB deficient mutant. Our findings suggest that Rv1096 may deacetylate PGNs to evade PRRs recognition, thus protecting Mtb from host immune surveillance and clearance in macrophages.

结核分枝杆菌（Mtb）是一种细胞内病原体，可以感染并在巨噬细胞中复制。肽聚糖（PGN）是分枝杆菌细胞壁的主要成分，可被宿主模式识别受体（PRR）识别。许多细菌通过PGN脱乙酰作用来调节和逃避宿主的免疫防御。Rv1096以前被表征为Mtb中的PGN N-脱乙酰基酶基因。然而，Rv1096调节巨噬细胞感染期间宿主免疫防御的基本机制仍不清楚。在本研究中，我们调查了Rv1096在使用重组耻垢分枝杆菌逃避宿主免疫力中的作用表达外源Rv1096和Rv1096-缺失的Mtb菌株H37Rv突变体。我们发现Rv1096促进了细胞内细菌的存活，并抑制了耻垢分枝杆菌或Mtb感染的巨噬细胞的炎症反应。巨噬细胞中分枝杆菌诱导的炎症反应的抑制至少部分归因于TLR和NOD信号通路下游的NF-κB和MAPK活化。此外，我们发现Rv1096对炎症反应的抑制作用与TLR2，TLR4和NOD2相关。最后，我们通过傅里叶变换IR和Rv1096 NODB缺陷型突变体证明了Rv1096的PGN脱乙酰酶活性。我们的发现表明，Rv1096可能使PGN脱乙酰基，从而逃避PRR的识别，从而保护Mtb免受宿主免疫监视和巨噬细胞清除。