Biomedical subjects

Abhishek Mishra

Publications and source records attributed to Abhishek Mishra.

3 recordsLinked to original sources

PubMed2026

Construction and characterization of novel Mycobacterium tuberculosis-derived triple and quadruple knockout vaccines against tuberculosis.

Tuberculosis (TB) is a deadly disease that claims the lives of over a million people each year worldwide. The Bacille Calmette-Guérin vaccine has long been used to protect against TB, but it produces variable effects across different populations and fails to protect against adult pulmonary TB. Therefore, there is an urgent need for alternative vaccines that can offer better protection. We have developed a strategy for the rational deletion of virulence-related genes in Mycobacterium tuberculosis (Mtb) to create hyperattenuation that also enhances immunogenicity. Previously, we generated both single (∆fbpA) and double knockout (DKO) (∆fbpA-∆sapM) mutants of Mtb and assessed their immunogenicity and efficacy using mice. Herein, we have created triple knockout (TKO) and quadruple knockout (QKO) strains to enhance the immunogenicity and safety of the DKO strain by deleting the zmp1 and dosR genes. The resulting TKO strains, TKO-Z (∆fbpA-∆sapM-∆zmp1) and TKO-D (∆fbpA-∆sapM-∆dosR), and the QKO strain (∆fbpA-∆sapM-∆zmp1-∆dosR), were evaluated for their immunogenicity and safety in mice. Whereas TKO-Z and QKO strains exhibited superior immunogenicity compared to the DKO strain, their protective efficacy in mice was comparable. However, survival studies involving SCID mice indicated that the QKO strain was highly attenuated. Therefore, rational deletion of genes in Mtb seems to be an innovative approach for developing safer and more efficacious vaccines against TB.

Animals↗

PubMed2025

The pathway of autophagy in the epigenetic landscape of Mycobacterium-host interactions.

Macroautophagy (autophagy) is an evolutionarily conserved process that degrades excess cytoplasmic components, such as protein aggregates and damaged organelles, by encapsulating them within double-membrane autophagosomes. These autophagosomes undergo distinct stages - initiation, phagophore nucleation, expansion, and closure - before fusing with lysosomes (or occasionally endosomes) for degradation and recycling. This process is regulated by ATG (autophagy related) proteins, which govern autophagosome formation and lysosomal fusion. Epigenetic modifications and transcription factors can regulate ATG gene expression in the nucleus. Autophagy also plays a key role in eliminating intracellular Mycobacterium tuberculosis (Mtb) through the lytic and antimicrobial activities of autolysosomes, which are more potent antimicrobial compartments than conventional phagosomes. Emerging evidence suggests that Mtb can modify the host epigenome and transcriptional machinery, significantly affecting the host immune response. This review explores the epigenetic regulation of autophagy during mycobacterium-host interactions. The interplay between epigenetic regulation and autophagy highlights a crucial aspect of host-pathogen interactions during Mtb infection. Understanding how Mtb manipulates the host epigenome to regulate autophagy could lead to the development of novel therapeutic strategies that enhance autophagic pathways or counteract Mtb's immune evasion tactics.Abbreviations: AM: Alveolar macrophages; ATG: autophagy related; DNMT: DNA methyltransferase; FOXO3: forkhead box O3; HAT: histone acetyltransferase; HDAC: histone deacetylase; MIR: microRNA; MTOR: mechanistic target of rapamycin kinase; Mtb: Mycobacterium tuberculosis; ROS: reactive oxygen species; SIRT: sirtuin; STPK: serine/threonine protein kinase.

Autophagy↗

PubMed2022

Human Macrophages Exhibit GM-CSF Dependent Restriction of Mycobacterium tuberculosis Infection via Regulating Their Self-Survival, Differentiation and Metabolism.

GM-CSF is an important cytokine that regulates the proliferation of monocytes/macrophages and its various functions during health and disease. Although growing evidences support the notion that GM-CSF could play a major role in immunity against tuberculosis (TB) infection, the mechanism of GM-CSF mediated protective effect against TB remains largely unknown. Here in this study we examined the secreted levels of GM-CSF by human macrophages from different donors along with the GM-CSF dependent cellular processes that are critical for control of M. tuberculosis infection. While macrophage of different donors varied in their ability to produce GM-CSF, a significant correlation was observed between secreted levels of GM-CSF, survial of macrophages and intra-macrophage control of Mycobacterium tuberculosis bacilli. GM-CSF levels secreted by macrophages negatively correlated with the intra-macrophage M. tuberculosis burden, survival of infected host macrophages positively correlated with their GM-CSF levels. GM-CSF-dependent prolonged survival of human macrophages also correlated with significantly decreased bacterial burden and increased expression of self-renewal/cell-survival associated genes such as BCL-2 and HSP27. Antibody-mediated depletion of GM-CSF in macrophages resulted in induction of significantly elevated levels of apoptotic/necrotic cell death and a simultaneous decrease in autophagic flux. Additionally, protective macrophages against M. tuberculosis that produced more GM-CSF, induced a stronger granulomatous response and produced significantly increased levels of IL-1β, IL-12 and IL-10 and decreased levels of TNF-α and IL-6. In parallel, macrophages isolated from the peripheral blood of active TB patients exhibited reduced capacity to control the intracellular growth of M. tuberculosis and produced significantly lower levels of GM-CSF. Remarkably, as compared to healthy controls, macrophages of active TB patients exhibited significantly altered metabolic state correlating with their GM-CSF secretion levels. Altogether, these results suggest that relative levels of GM-CSF produced by human macrophages plays a critical role in preventing cell death and maintaining a protective differentiation and metabolic state of the host cell against M. tuberculosis infection.

Cell Differentiation↗