Proteomic Profiling Reveals the Architecture of Granulomatous Lesions Caused by Tuberculosis and Mycobacterium avium Complex Lung Disease

Abstract

Tuberculosis (TB) and Mycobacterium avium complex lung disease (MAC-LD) are both characterized pathologically by granuloma lesions, which are typically composed of a necrotic caseum at the center surrounded by fibrotic cells and lymphocytes. Although the histological characterization of TB and MAC-LD granulomas has been well-documented, their molecular signatures have not been fully evaluated. In this research we applied mass spectrometry-based proteomics combined with laser microdissection to investigate the unique protein markers in human mycobacterial granulomatous lesions. Comparing the protein abundance between caseous and cellular sub-compartments of mycobacterial granulomas, we found distinct differences. Proteins involved in cellular metabolism in transcription and translation were abundant in cellular regions, while in caseous regions proteins related to antimicrobial response accumulated. To investigate the determinants of their heterogeneity, we compared the protein abundance in caseous regions between TB and MAC-LD granulomas. We found that several proteins were significantly abundant in the MAC-LD caseum of which proteomic profiles were different from those of the TB caseum. Immunohistochemistry demonstrated that one of these proteins, Angiogenin, specifically localized to the caseous regions of selected MAC-LD granulomas. We also detected peptides derived from mycobacterial proteins in the granulomas of both diseases. This study provides new insights into the architecture of granulomatous lesions in TB and MAC-LD.

Antimycobacterial Potential of Mycobacteriophage Under Disease-Mimicking Conditions

“…Several species of Mycobacterium exist as intracellular pathogens in acidic and hypoxic environments ( Sibling et al, 1987 ; Oh and Straubinger, 1996 ; Rastogi et al, 2001 ; Houben et al, 2006 ; Benítez-Guzmán et al, 2019 ; Seto et al, 2020 ). In order for phage therapy to be efficient against such mycobacterial infections, phages need to retain their activity and infectivity in these extreme environments.…”

“…Various Mycobacterium species ( M. tuberculosis , M. avium complex, M. bovis , and M. leprae ) are found to reside intracellularly at low pH conditions which poses a challenge in efficacy of anti-bacterials ( Sibling et al, 1987 ; Oh and Straubinger, 1996 ; Ehlers and Schaible, 2012 ; Benítez-Guzmán et al, 2019 ). M. tuberculosis and M. avium complex also form granulomatous structures, marked by a gradient of hypoxia, nutrient deprivation and acidity ( Timm et al, 2003 ; Voskuil et al, 2004 ; Lawn and Zumla, 2011 ; Ehlers and Schaible, 2012 ; Seto et al, 2020 ). For a phage to successfully eliminate these bacilli, it needs to be active and efficient under such low pH and hypoxic conditions and should be able to enter into the eukaryotic cells.…”

Antimycobacterial potential of Mycobacteriophage under disease-mimicking conditions

“…Several species of Mycobacterium exist as intracellular pathogens in acidic and hypoxic environments (Sibling et al, 1987; Oh and Straubinger, 1996; Rastogi et al, 2001; Houben et al, 2006; Benítez-Guzmán et al, 2019; Seto et al, 2020). In order for phage therapy to be efficient against such mycobacterial infections, phages need to retain their activity and infectivity in these extreme environments.…”

“…Various Mycobacterium species ( M. tuberculosis , M. avium complex, M. bovis and M. leprae ) are found to reside intracellularly at low pH conditions which poses a challenge in efficacy of anti-bacterials (Sibling et al, 1987; Oh and Straubinger, 1996; Ehlers and Schaible, 2012; Benítez-Guzmán et al, 2019). M. tuberculosis and M. avium complex also form granulomatous structures, marked by a gradient of hypoxia, nutrient deprivation and acidity (Timm et al, 2003; Voskuil et al, 2004; Lawn and Zumla, 2011; Ehlers and Schaible, 2012; Seto et al, 2020). For a phage to successfully eliminate these bacilli, it needs to be active and efficient under such low pH and hypoxic conditions and should be able to enter into the eukaryotic cells.…”

Tolerance and Persistence to Drugs: A Main Challenge in the Fight Against Mycobacterium tuberculosis

“…Liquefied caseum that reaches an adjacent airway stimulates the cough reflex facilitating bacterial dissemination ( Marakalala et al, 2016 ). Granulomas caseous centers represent a pro-inflammatory environment characterized by anoxia and the presence of several proteins and lipids deriving from cellular necrosis, as well as reactive oxygen species, pro-inflammatory eicosanoids, and antimicrobial peptides ( Marakalala et al, 2016 ; Seto et al, 2019 ). Sarathy et al (2018) showed that M. tuberculosis residing in caseum is not able to replicate and become highly tolerant to several first‐ and second-line anti tubercular drugs following a trend similar to that observed in in vitro models of non-replicative M. tuberculosis based on hypoxia or starvation.…”