Project description:Aging has a significant impact on the immune system, leading to a gradual decline in immune function and changes in the body's ability to respond to bacterial infections. Non-tuberculous mycobacteria (NTM), also known as atypical mycobacteria or environmental mycobacteria, are commonly found in soil, water, and various environmental sources. While many NTM species are considered opportunistic pathogens, some can cause significant infections, particularly in individuals with compromised immune systems, such as the elderly. When mycobacteria enter the body, macrophages are among the first immune cells to encounter them, and attempt to engulf mycobacteria through a process called phagocytosis. Some NTM species, including Mycobacterium avium (M.avium) can survive and replicate within macrophages. However, little is known about the interaction between NTM and macrophages in the elderly. In this study, we investigated the mouse bone marrow-derived macrophage (BMMs) response to M. avium serotype 4, one of the main NTM species in patients with pulmonary NTM diseases. Our results demonstrated that old mouse BMMs have an increased level of intracellular iron and are more susceptible to M. avium serotype 4 infection compared to young mouse BMMs. The whole-cell proteomic analysis indicated a dysregulated expression of iron homeostasis-associated proteins in old mouse BMMs regardless of mycobacterial infection. Deferoxamine, an iron chelator, significantly rescued mycobacterial killing and phagolysosome maturation in old mouse BMMs. Therefore, our data indicate that an intracellular iron overload improves NTM survival within macrophages, and suggest a potential application of iron chelating drugs as a host-directed therapy for pulmonary NTM infection in the elderly
Project description:Lung disease due to non-tuberculous mycobacteria (NTM) is rising in incidence. While both 2D cell culture and animal models exist for NTM infections, a major knowledge gap is the early responses of human alveolar and innate immune cells to NTM within the human lung microenvironment. Here we describe development of a humanized, 3D, alveolus lung-on-a-chip (ALoC) model of Mycobacterium fortuitum infection that incorporates only primary human cells such as pulmonary vascular endothelial cells in a vascular channel, and type I and II alveolar cells and monocyte-derived macrophages in an alveolar channel along an air-liquid interface. M. fortuitum introduced into the alveolar channel primarily infected macrophages, with rare bacteria inside alveolar cells. Bulk-RNA sequencing of infected chips revealed marked upregulation of transcripts for cytokines, chemokines and secreted protease inhibitors (SERPINs). Our results demonstrate how a humanized ALoC system can identify critical early immune and epithelial responses to M. fortuitum infection. We envision potential application of the ALoC to other NTM and for studies of new antibiotics
Project description:Non-tuberculous mycobacteria (NTM) are emerging pathogens with high intrinsic drug resistance. Among rapidly growing NTM species, Mycobacterium abscessus is among the most pathogenic. Standard of care therapy has led to unacceptable outcomes and demonstrates the urgent need to develop effective, broad-spectrum antimycobacterial regimens. Through synthetic modification of spectinomycin (SPC), an aminocyclitol antibiotic, we have identified a distinct structural subclass of ethylene linked aminomethyl spectinomycins (eAmSPC) that are up to 64-fold more potent against M. abscessus when compared to SPC. Lead eAmSPC retain activity against other NTM species and multi-drug resistant M. abscessus clinical isolates. Sequencing of eAmSPC-resistant mutants revealed nucleotide changes in the distinct helix-34 spectinomycin binding site and X-ray crystallography further demonstrated the derivatives mode of ribosomal inhibition remained on target. The eAmSPC displayed increased intracellular accumulation compared to SPC and transcriptional profiling indicate that eAmSPC’s induce whiB7 resistance responses, however, the series maintains potency despite its expression. These leads display favorable pharmacokinetic profiles and robust efficacy in M. abscessus mouse infection models. The results of these studies suggest that eAmSPCs have the potential to be developed into clinical treatments for M. abscessus and other NTM infections.
Project description:Background: Patients with cystic fibrosis (CF) have an elevated lifetime risk of infection and disease caused by nontuberculous mycobacteria (NTM). Currently, there is no method to predict whether patients with cystic fibrosis will develop disease related to non-tuberculous mycobacteria. In non cystic fibrosis populations, several genetic susceptibility factors have been described. In this study, we examined whether patients with cystic fibrosis demonstrate a similar pattern of genetic susceptibility and explored host immune-related biomarkers predictive of NTM pulmonary disease (NTM-PD). Methods: We evaluated whole blood gene expression using bulk RNA-seq in a cohort of CF patients at the time of first isolation of NTM. Differential gene expression was compared in patients who did (n = 12) vs. did not (n= 30) develop NTM-PD following first NTM growth. Results: No differences in demographics or composition of white blood cell sample populations at the time of sample collection were identified between groups. There were no significant differences in the expression of genes previously reported to confer susceptibility to NTM-PD in non-CF populations. However, CF patients who went on to develop NTM-PD had higher expression of genes involved in the interferon ( and ), tumor necrosis factor, and IL6 STAT3 JAK pathways. Conclusion: Patients with CF who develop NTM-PD have increased expression of genes involved in innate immunity, in contrast to non-CF populations where these responses seem to be suppressed.
Project description:Bacille Calmette Guerin (BCG) is the only licensed vaccine against Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB) disease. However, BCG has limited efficacy, necessitating the development of better vaccines. Non-tuberculous mycobacteria (NTM), a distinct lineage from Mtb, are opportunistic pathogens present in the environment. TB endemic countries experience higher exposure to NTM, but previous studies have not elucidated the relationship between NTM exposure and BCG efficacy. Therefore, we developed a mouse model (BCG+NTM) that mimics human BCG vaccination at an early stage and continuous NTM exposure via the oral route, including during TB infection. Our results show that BCG+NTM mice had improved protection against pulmonary TB correlating with increased pulmonary influx of B-cells, higher titers of anti-Mtb IgA and IgG antibodies in serum and airways, compared to mice vaccinated with BCG alone. Notably, the lungs of BCG+NTM mice developed B-cell aggregates expressing markers of germinal center formation as determined by spatial transcriptomics. We conclude a direct correlation between NTM exposure and protection from TB, with B-cells playing a crucial role.
Project description:Tuberculosis (TB) is still a major global health challenge, killing over 1.5 million people each year, and hence, there is a need to identify and develop novel treatments for Mycobacterium tuberculosis (M. tuberculosis). The prevalence of infections caused by nontuberculous mycobacteria (NTM) is also increasing and has overtaken TB cases in the United States and much of the developed world. Mycobacterium abscessus (M. abscessus) is one of the most frequently encountered NTM and is difficult to treat. We describe the use of drug-disease association using a semantic knowledge graph approach combined with machine learning models that has enabled the identification of several molecules for testing anti-mycobacterial activity. We established that niclosamide (M. tuberculosis IC90 2.95 μM; M. abscessus IC90 59.1 μM) and tribromsalan (M. tuberculosis IC90 76.92 μM; M. abscessus IC90 147.4 μM) inhibit M. tuberculosis and M. abscessus in vitro. To investigate the mode of action, we determined the transcriptional response of M. tuberculosis and M. abscessus to both compounds in axenic log phase, demonstrating a broad effect on gene expression that differed from known M. tuberculosis inhibitors. Both compounds elicited transcriptional responses indicative of respiratory pathway stress and the dysregulation of fatty acid metabolism. Further testing against drug-resistant isolates and other NTM is warranted to clarify the usefulness of these repurposed drugs for mycobacteria.
Project description:Mycobacterium abscessus is one of the common clinical non-tuberculous mycobacteria (NTM) which can cause severe skin infections. 5-Aminolevulinic acid photodynamic therapy (ALA_PDT) is an emerming effective antimicrobial medication. To explore whether ALA_PDT can treat M. abscessus infections, we found that ALA_PDT can kill M. abscesses via colony forming unit method. ALA_PDT promoted ferroptosis-like death of M. abscesses, and the antioxidant N-Acetyl-L-cysteine (NAC) and ferroptosis inhibitor Ferrostatin-1(Fer-1) can mitigate the ALA_PDT-mediated sterilization. Furthermore, ALA_PDT significantly up-regulated the transcription of heme oxygenase MAB_4773, increased the intracellular Fe2+ concentration, altering the transcription of M. abscessus iron metabolism genes. ALA_PDT disrupted the integrity of the cell membrane and enhanced the permeability of the cell membrane, as evidenced by the boosted sterilization effect of antibiotics. In summary, ALA_PDT can kill M. abscesses via promoting the ferroptosis-like death and antibiotic sterilization through oxidative stress. This new mechanism of ALA_PDT against M. abscessus might underlie its clinical efficacy.