Interaction of alveolar epithelial cells with CFP21, a mycobacterial cutinase-like enzyme
Pooja Vir1, Dheeraj Gupta, Ritesh Agarwal
1Department of Biochemistry, Postgraduate Institute of Medical Education and Research, Sector-12, Chandigarh, 160012, India.
Abstract:
Mycobacterium tuberculosis (M. tb), an intracellular pathogen, has the ability to infect alveolar epithelial cells (AEC) also in addition to alveolar macrophages. The virulence of M. tb is attributed to proteins encoded by genomic regions of deletion (RD) and till date 16 such regions (RD1-RD16) have been identified. Culture filtrate protein 21 (CFP21), a RD2 secretory protein, is a cutinase-like enzyme that possesses esterase and lipolytic activity. It is hypothesized that CFP21 could be playing a role in M. tb virulence by disrupting the host cell integrity. In this study, recombinant CFP21 was expressed and purified. The in vitro exposure of type I (WI26) and type II (A549) AEC to CFP21 resulted in a significant decline in their cellular viability by inducing cell apoptosis. However, the cytotoxic effects were more pronounced in WI26 cells than in A549 cells. The analysis of immune responses in CFP21-treated AEC exhibited significant production of reactive oxygen species and anti-inflammatory cytokine TGF-β which indicated oxidative stress-mediated cell death. These results show that CFP21 could play an important role in M. tb pathogenesis by disrupting the host alveolar barrier and thereby facilitating mycobacterial dissemination.
Insights
Mycobacterium tuberculosis secretes CFP21, a protein that damages alveolar epithelial cells (AEC) by inducing apoptosis and oxidative stress. This disruption of the lung barrier aids tuberculosis (TB) pathogen spread.
Area of Science:
- Cellular microbiology
- Immunology
- Pathogenesis
Background:
- Mycobacterium tuberculosis (M. tb) infects alveolar macrophages and epithelial cells.
- Virulence factors, including proteins from genomic deletion regions (RDs), contribute to M. tb pathogenesis.
- Culture filtrate protein 21 (CFP21), a RD2 protein, has esterase and lipolytic activity, suggesting a role in host cell disruption.
Purpose of the Study:
- To investigate the role of CFP21 in M. tb virulence by examining its effects on alveolar epithelial cells (AEC).
- To determine if CFP21 disrupts host cell integrity and induces immune responses.
Main Methods:
- Recombinant CFP21 was expressed and purified.
- In vitro exposure of type I (WI26) and type II (A549) AEC to CFP21.
- Assessment of cellular viability, apoptosis, reactive oxygen species (ROS) production, and TGF-β cytokine levels.
Main Results:
- CFP21 significantly reduced AEC viability by inducing apoptosis in both WI26 and A549 cell lines.
- Cytotoxic effects were more pronounced in WI26 cells compared to A549 cells.
- CFP21-treated AEC showed increased ROS production and TGF-β levels, indicating oxidative stress and an anti-inflammatory response.
Conclusions:
- CFP21 contributes to M. tb pathogenesis by damaging the host alveolar barrier.
- CFP21-induced disruption of AEC integrity facilitates mycobacterial dissemination.
- Oxidative stress and altered immune responses are key mechanisms in CFP21-mediated cell death.
