Biology subjects

Rothchild, A. C.

Publications and source records attributed to Rothchild, A. C..

7 recordsLinked to original sources

bioRxiv2026

Modulation of Ferroptosis During Early Mycobacterium tuberculosis Infection Contributes to Beijing Lineage Strain SA161 Virulence

Although spread of internalized Mtb from the initial infected alveolar macrophages (AMs) is a crucial determinant of infection outcomes, the role of cell death in facilitating this spread, and how it is regulated by Mtb remains poorly understood. Ferroptosis, a lipid peroxidation-mediated form of necrotic cell death, contributes to pathology during later stages of infection. However, the role of ferroptosis in early AM cell death remains inadequately defined, and its induction during infection has been primarily studied with the laboratory strain, H37Rv. Using gene set variation analysis of single cell RNAseq data profiling Mtb-infected murine lungs, we found that the hypervirulent Beijing sublineage clinical strain SA161 is associated with an elevated pro-ferroptotic transcriptional response in AMs compared to H37Rv by 17 days post infection. Consistent with these transcriptional profiles, we found that SA161 induced increased lipid peroxidation in comparison to H37Rv during infection in vitro and in vivo. Administration of the lipid peroxidation inhibitor, ferrostatin-1 (Fer-1), reduces this Mtb-induced lipid peroxidation. Notably, we found that administration of Fer-1 to Mtb-infected mice significantly reduced bacterial burden for SA161 at 14 dpi while having no effect on H37Rv. Microscopic analysis of SA161-infected lung lesions at 14 dpi suggests that inhibition of ferroptosis-driving lipid peroxidation results in a greater proportion of AMs amongst infected cells and decreased neutrophil-associated IFN signaling. Collectively, these findings reveal that ferroptosis plays an important role during early infection with virulent clinical strains of Mtb by influencing bacterial spread and signaling of immune cell responders, potentially informing host-directed intervention strategies.

immunology↗

bioRxiv2025

NRF2 inhibition of alveolar macrophage MHC II expression during Mycobacterium tuberculosis infection

During Mycobacterium tuberculosis (Mtb) infection, infected alveolar macrophages (AMs) initially up-regulate a NRF2 regulated cell-protective program, which is detrimental to host control and impedes AM activation, including MHC II expression. MHC II is critical for CD4+ T cell activation and host immunity during Mtb infection. We hypothesized that NRF2 regulates the MHC II pathway and AM antigen presentation to T cells. We found that NRF2 inhibits MHC II, but not MHC I, specifically in AMs, following Mtb infection in vitro and in vivo. NRF2 dampens Ciita and H2-Ab1 gene expression in uninfected AMs, and MHC II inhibition by NRF2 is retained following innate stimuli and IFN{gamma} exposure. NRF2 expression in Mtb-infected AMs impedes their ability to activate ESAT6-specific CD4+ T cells. Thus, although NRF2 expression enhances cell-protective functions, it has the unexpected consequence of limiting innate-adaptive crosstalk, which can impair CD4+ T cell activation and host immunity during Mtb infection. HIGHLIGHTSO_LINRF2 inhibits MHC II on AMs, but not DCs, MDMs, or PMNs, during Mtb infection C_LIO_LINRF2 inhibits Ciita and H2-Ab1 and total MHC II protein in AMs, but not in BMDMs C_LIO_LINRF2 blockade of AM MHC II is retained following PAMP and IFN{gamma} stimulation C_LIO_LINRF2 impedes the activation of antigen-specific CD4+ T cells by Ams C_LI

immunology↗

bioRxiv2025

Shared and distinct responses of human and murine alveolar macrophages and monocyte-derived macrophages to Mycobacterium tuberculosis

Macrophages serve as important sites of bacterial replication and host immune response during Mycobacterium tuberculosis (Mtb) infection with distinct roles for alveolar macrophages (AMs) early in infection and monocyte-derived (MDMs) during later stages of disease. Here, we leverage data from human and mouse models to perform a cross-species analysis of macrophage responses to Mtb infection. Overall, we find that both subsets of human and murine macrophages mount a strong interferon response to Mtb infection. However, AM across both species do not generate as strong a pro-inflammatory response as human MDMs or murine bone marrow-derived macrophages (BMDMs), as characterized by TNFA signaling and inflammatory response pathways. Interestingly, AMs from mice that were previously vaccinated with BCG (scBCG) or from a model of contained TB (coMtb) had Mtb responses that were more similar to human AMs than control mice. We also identify species-specific pathways altered by infection differently in mouse and human macrophages, specifically in pathways related to cholesterol in AMs as well as MYC targets and Hedgehog signaling in MDMs/BMDMs. Lastly, to investigate downstream effects of the macrophage interferon responses, we examine macrophage expression of IL-10, an immunosuppressive cytokine induced by Type I Interferons, and c-Maf, a transcription factor required for IL-10 expression in myeloid cells. We find that c-Maf and IL-10 have significantly lower expression in AMs compared to MDMs in both humans and mice, suggesting one possible mechanism by which AMs mount a stronger interferon response following Mtb infection. Overall, these results highlight the dynamics of innate myeloid responses over the course of Mtb infection and the benefit of a combined analysis across species to reveal conserved and unique responses.

immunology↗

bioRxiv2024

Absence of c-Maf and IL-10 enables Type I IFN enhancement of innate responses to low-dose LPS in alveolar macrophages

Alveolar macrophages (AMs) are lower-airway resident myeloid cells and are among the first to respond to inhaled pathogens. Here, we interrogate AM innate sensing to Pathogen Associated Molecular Patterns (PAMPs) and determine AMs have decreased responses to low- dose LPS compared to other macrophages, as measured by TNF, IL-6, Ifnb, and Ifit3. We find the reduced response to low-dose LPS correlates with minimal TLR4 and CD14 surface expression, despite sufficient internal expression of TLR4. Additionally, we find that AMs do not produce IL-10 in response to a variety of PAMPs due to low expression of transcription factor c- Maf and that lack of IL-10 production contributes to an enhancement of pro-inflammatory responses by Type I IFN. Our findings demonstrate that AMs have cell-intrinsic dampened responses to LPS, which is enhanced by type I IFN exposure. These data implicate conditions where AMs may have reduced or enhanced sentinel responses to bacterial infections. HIGHLIGHTSO_LIAlveolar macrophages (AMs) do not produce TNF or IL-6 in response to low-dose LPS due to minimal surface expression of TLR4 and CD14 C_LIO_LILack of AM IL-10 production is dependent on low c-Maf expression C_LIO_LIExogenous c-Maf expression increases AM IL-10 production C_LIO_LIIFN{beta} enhances AM TNF and IL-6 responses to low-dose LPS and this is dependent on a lack of IL-10 C_LI

immunology↗

bioRxiv2022

Mycobacterial exposure remodels alveolar macrophages and the early innate response to Mycobacterium tuberculosis infection

Alveolar macrophages (AMs) play a critical role during Mycobacterium tuberculosis (Mtb) infection as the first cells in the lung to encounter bacteria. We previously showed that AMs initially respond to Mtb in vivo by mounting a cell-protective, rather than pro-inflammatory response. However, the plasticity of the initial AM response was unknown. Here, we characterize how previous exposure to mycobacterium, either through subcutaneous vaccination with Mycobacterium bovis (scBCG) or through a contained Mtb infection (coMtb) that mimics aspects of concomitant immunity, impacts the initial response by AMs. We find that both scBCG and coMtb accelerate early innate cell activation and recruitment and generate a stronger pro-inflammatory response to Mtb in vivo by AMs. Within the lung environment, AMs from scBCG vaccinated mice mount a robust interferon-associated response, while AMs from coMtb mice produce a broader inflammatory response that is not dominated by Interferon Stimulated Genes. Using scRNAseq, we identify changes to the frequency and phenotype of airway-resident macrophages following mycobacterium exposure, with enrichment for both interferon-associated and pro-inflammatory populations of AMs. In contrast, minimal changes were found for airway-resident T cells and dendritic cells after exposures. Ex vivo stimulation of AMs with Pam3Cys, LPS and Mtb reveal that scBCG and coMtb exposures generate stronger interferon-associated responses to LPS and Mtb that are cell-intrinsic changes. However, AM profiles that were unique to each exposure modality following Mtb infection in vivo are dependent on the lung environment and do not emerge following ex vivo stimulation. Overall, our studies reveal significant and durable remodeling of AMs following exposure to mycobacterium, with evidence for both AM-intrinsic changes and contributions from the altered lung microenvironments. Comparisons between the scBCG and coMtb models highlight the plasticity of AMs in the airway and opportunities to target their function through vaccination or host-directed therapies. Author SummaryTuberculosis, a disease caused by the bacteria Mycobacterium tuberculosis (Mtb), claims around 1.6 million lives each year, making it one of the leading causes of death worldwide by an infectious agent. Based on principles of conventional immunological memory, prior exposure to either Mtb or M. bovis BCG leads to antigen-specific long-lasting changes to the adaptive immune response that can be effective at protecting against subsequent challenge. However, how these exposures may also impact the innate immune response is less understood. Alveolar macrophages are tissue-resident myeloid cells that play an important role during Mtb infection as innate immune sentinels in the lung and the first host cells to respond to infection. Here, we examined how prior mycobacterium exposure, either through BCG vaccination or a model of contained Mtb infection impacts the early innate response by alveolar macrophages. We find that prior exposure remodels the alveolar macrophage response to Mtb through both cell-intrinsic changes and signals that depend on the altered lung environment. These findings suggest that the early innate immune response could be targeted through vaccination or host-directed therapy and could complement existing strategies to enhance the host response to Mtb.

immunology↗

bioRxiv2019

Alveolar macrophages up-regulate a non-classical innate response to Mycobacterium tuberculosis infection in vivo

Alveolar macrophages (AMs) are the first cells to be infected during Mycobacterium tuberculosis (Mtb) infection. Thus the AM response to infection is the first of many steps leading to initiation of the adaptive immune response, which is required for efficient control of infection. A hallmark of Mtb infection is the delay of the adaptive response, yet the mechanisms responsible for this delay are largely unknown. We developed a system to identify, sort and analyze Mtb-infected AMs from the lung within the first 10 days of infection. In contrast to what has been previously described using in vitro systems, we find that Mtb-infected AMs up-regulate a cell-protective antioxidant transcriptional signature that is dependent on the lung environment and not dependent on bacterial virulence. Computational approaches including pathway analysis and transcription factor binding motif enrichment analysis identify Nrf2 as a master regulator of the response of AMs to Mtb infection. Using knock-out mouse models, we demonstrate that Nrf2 drives the expression of the cell protective transcriptional program and impairs the ability of the host to control bacterial growth over the first 10 days of infection. Mtb-infected AMs exhibit a highly delayed pro-inflammatory response, and comparisons with uninfected AMs from the same infected animals demonstrate that inflammatory signals in the lung environment are blocked in the Mtb-infected cells. Thus, we have identified a novel lung-specific transcriptional response to Mtb infection that impedes AMs from responding rapidly to intracellular infection and thereby hinders the overall immune response.\n\nOne Sentence SummaryIn response to Mtb infection in vivo, alveolar macrophages fail to up-regulate the canonical pro-inflammatory innate response and instead induce an Nrf2-dependent cell protective transcriptional program, which in turn impairs the hosts control of bacterial growth.

immunology↗

bioRxiv2018

An essential mycolate remodeling program for mycobacterial adaptation in host cells

The success of Mycobacterium tuberculosis (MTB) stems from its ability to remain hidden from the immune system within macrophages. Here, we report a new technology (Path-seq) to sequence miniscule amounts of MTB transcripts within up to million-fold excess host RNA. Using Path-seq we have discovered a novel transcriptional program for in vivo mycobacterial cell wall remodeling when the pathogen infects alveolar macrophages in mice. We have discovered that MadR transcriptionally modulates two mycolic acid desaturases desA1/A2 to initially promote cell wall remodeling upon in vitro macrophage infection and, subsequently, reduces mycolate biosynthesis upon entering dormancy. We demonstrate that disrupting MadR program is lethal to diverse mycobacteria making this evolutionarily conserved regulator a prime antitubercular target for both early and late stages of infection.\n\nOne Sentence SummaryNovel technology (Path-seq) discovers cell wall remodeling program during Mycobacterium tuberculosis infection of macrophages

microbiology↗