Proteomics approach to understand reduced clearance of mycobacteria and high viral titers during HIV–mycobacteria co‐infection

Abstract

Environmental mycobacteria, highly prevalent in natural and artificial (including chlorinated municipal water) niches, are emerging as new threat to human health, especially to HIV-infected population. These seemingly harmless non-pathogenic mycobacteria, which are otherwise cleared, establish as opportunistic infections adding to HIV-associated complications. Although immune-evading strategies of pathogenic mycobacteria are known, the mechanisms underlying the early events by which opportunistic mycobacteria establish infection in macrophages and influencing HIV infection are unclear. Proteomics of phagosome-enriched fractions from Mycobacterium bovis Bacillus Calmette-Guérin (BCG) mono-infected and HIV-M. bovis BCG co-infected THP-1 cells by LC-MALDI-MS/MS revealed differential distribution of 260 proteins. Validation of the proteomics data showed that HIV co-infection helped the survival of non-pathogenic mycobacteria by obstructing phagosome maturation, promoting lipid biogenesis and increasing intracellular ATP equivalents. In turn, mycobacterial co-infection up-regulated purinergic receptors in macrophages that are known to support HIV entry, explaining increased viral titers during co-infection. The mutualism was reconfirmed using clinically relevant opportunistic mycobacteria, Mycobacterium avium, Mycobacterium kansasii and Mycobacterium phlei that exhibited increased survival during co-infection, together with increase in HIV titers. Additionally, the catalogued proteins in the study provide new leads that will significantly add to the understanding of the biology of opportunistic mycobacteria and HIV coalition.

Understanding HIV-Mycobacteria synergism through comparative proteomics of intra-phagosomal mycobacteria during mono- and HIV co-infection

“…Glyoxylate pathway utilizes the C2 substrates from fatty acids, which are abundantly found in mammalian cells, without generating carbon dioxide and help in the persistence of mycobacteria during nutrient stress 46 . This was consistent with our observation of increased lipid body accumulation in host during co-infection 21 and mycobacteria adaptation to the host niche by concomitant expression of malate synthase. Isopropylmalate synthase and Acetolactate synthase, which were upregulated during co-infection, are involved in the synthesis of branched chain amino acids, Leucine, Isoleucine and Valine which may provide survival advantage during co-infection 49 50 .…”

“…This cell culture based set up simulated a condition when an HIV patient acquired secondary mycobacterial infection. In compliance with the clinical observations on HIV-mycobacterial co-infections, the co-infection of THP-1 with HIV and mycobacteria resulted in higher propagation of both the virus and the bacteria 21 .…”

“…We also observed that mycobacteria tend to adapt to the intracellular niche provided by HIV during co-infection by altering its protein complement. For instance, concurrent to the increased host lipid accumulation inside macrophages during co-infection 21 , it increases the expression of lipid utilizing mycobacterial enzymes or pathways during co-infection. Another significant observation from the data is the increased expression of proteins involved in altering the lipid and protein composition of the cell wall.…”

Histone methyltransferase SUV 39H1 participates in host defense by methylating mycobacterial histone‐like protein HupB

“…This was also confirmed by examining the number of viable intracellular bacteria as quantified by Alamar assay (Ganji et al , ) counting. Significantly more numbers of GFP:: M. bovis BCG bacilli were found in infected SUV39H1‐KD as compared to control macrophages (Fig D).…”

Mycobacterium tuberculosis Zinc Metalloprotease-1 Assists Mycobacterial Dissemination in Zebrafish

“…The CHO cell lines were maintained in RPMI media supplemented with 10% FBS and incubated at 37°C with 5% CO 2 . The media was changed when the cells reached 90% confluency, the cells were trypsinized with the Trypsin-EDTA (Sigma) and washed with phosphate buffered saline pH 7.4 (PBS) (Ganji et al, 2016b). …”