Biology subjects

McKee, S. R.

Publications and source records attributed to McKee, S. R..

5 recordsLinked to original sources

bioRxiv2025

1,2,4-Triazole-based first-in-class non-nucleoside inhibitors of bacterial enzyme MraY

MraY, a bacterial enzyme crucial for the synthesis of peptidoglycans, represents a promising yet underexplored target for the development of effective antibacterial agents. Nature has provided several classes of nucleoside inhibitors of MraY and scientists have modified these structures further to obtain natural product-like inhibitors of MraY. The natural products and their synthetic analogs suffer from non-optimal in vivo efficacy, and the synthetic complexity of the structures renders the synthesis and structure-activity relationship (SAR) studies of these molecules particularly challenging. In this study, we present our findings on the discovery of first-in-class 1,2,4-triazole-based MraY inhibitors that are not nucleoside-derived. A series of 1,2,4-triazole analogous were identified by a structure-activity-relationship (SAR) study using a structure-based drug design strategy. Compound 1, with an IC50 of 171 {micro}M against MraY from Staphylococcus aureus (MraYSA), was optimized to compound 12a, exhibiting an IC50 of 25 {micro}M. Molecular docking studies against MraYSA provided insights into these compounds binding interactions and activity. Furthermore, screening against the ESKAPE bacterial panel was also conducted, through which we discovered compounds demonstrating broad-spectrum antibacterial activity against E. faecium, methicillin-resistant S. aureus (MRSA), vancomycin-resistant Enterococci (VRE) strains and Mycobacterium tuberculosis. The novel, first-in-class non-nucleoside inhibitors of MraY highlighted in this work provide a strong proof-of-concept of how to leverage structural information of the protein to develop future antibacterial agents targeting MraY. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=168 SRC="FIGDIR/small/635793v1_ufig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@14b1f84org.highwire.dtl.DTLVardef@1024f45org.highwire.dtl.DTLVardef@a246d0org.highwire.dtl.DTLVardef@1d70e52_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2023

Type I IFN signaling in the absence of IRGM1 promotes M. tuberculosis replication in immune cells by suppressing T cell responses

Polymorphisms in the IRGM gene are associated with susceptibility to tuberculosis in humans. A murine ortholog of Irgm, Irgm1, is also essential for controlling Mycobacterium tuberculosis (Mtb) infection in mice. Multiple processes have been associated with IRGM1 activity that could impact the host response to Mtb infection, including roles in autophagy-mediated pathogen clearance and expansion of activated T cells. However, what IRGM1-mediated pathway is necessary to control Mtb infection in vivo and the mechanistic basis for this control remains unknown. We dissected the contribution of IRGM1 to immune control of Mtb pathogenesis in vivo and found that Irgm1 deletion leads to higher levels of IRGM3-dependent type I interferon signaling. The increased type I interferon signaling precludes T cell expansion during Mtb infection. The absence of Mtb-specific T cell expansion in Irgm1-/- mice results in uncontrolled Mtb infection in neutrophils and alveolar macrophages, which directly contributes to susceptibility to infection. Together, our studies reveal that IRGM1 is required to promote T cell-mediated control of Mtb infection in neutrophils, which is essential for the survival of Mtb-infected mice. These studies also uncover new ways type I interferon signaling can impact TH1 immune responses.

immunology↗

bioRxiv2023

Autophagy functions in lung macrophages and dendritic cells to suppress TH17 responses and neutrophil accumulation during allergic airway inflammation

Asthma affects 260 million people worldwide, with severe asthma cases that are associated with TH17/TH1 responses and neutrophil dominated inflammation being the most difficult to treat due to corticosteroid insensitivity. Single nucleotide polymorphisms in the ATG5 gene, which encodes for a protein required for the cellular recycling process of autophagy, are associated with higher risk for developing severe asthma. However, the role for ATG5 during allergic inflammation remains mostly unknown. We have identified an autophagy-dependent role for ATG5 in lung macrophages and dendritic cells (DCs) for suppressing TH17 responses and neutrophil accumulation in house dust mite (HDM)-challenged mice, a TH17/TH1 dominated model for allergic airway inflammation due to contamination of the HDM with lipopolysaccharide. In contrast, autophagy was required to promote eosinophil accumulation in the TH2-dominated ovalbumin model of allergic airway inflammation, supporting a model where autophagy functions in lung macrophages and DCs to suppress TH17 responses and promote TH2 responses in an allergen-dependent manner. In addition, we discover that autophagy is also required in macrophages exposed to HDM to suppress the secretion of cytokines and chemokines that would otherwise recruit neutrophils to the lungs, independent of T cell responses. Together, our data identify multiple roles for autophagy in suppressing the neutrophil accumulation in lungs that is associated with severe asthma.

immunology↗

bioRxiv2022

Discovery, Synthesis, and Optimization of 1,2,4-Triazolyl Pyridines Targeting Mycobacterium tuberculosis

Tuberculosis (TB) results in 1.5 million deaths every year. The rise in multi-drug resistant TB underscores the urgent need to develop new antibacterials, particularly those with new chemical entities and/or novel mechanisms of action that can be used in combination therapy with existing drugs to prevent the rapid emergence of resistance. Herein, we report the discovery and synthesis of a new series of compounds containing a 3-thio-1,2,4-triazole moiety that show inhibition of Mycobacterium tuberculosis (Mtb) growth and survival. Structure-activity relationship studies led us to identify potent analogs displaying nanomolar inhibitor activity, specifically against Mtb. These potent analogs exhibit a promising ADME/pharmacokinetic profile and no cytotoxicity in mammalian cells at over 100 times the effective dose in Mtb. Our preliminary investigations into the mechanism of action suggest this series is not engaging promiscuous targets and, thereby, could be acting on a novel target. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=79 SRC="FIGDIR/small/516356v1_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@1fd7a78org.highwire.dtl.DTLVardef@738c7dorg.highwire.dtl.DTLVardef@c7957org.highwire.dtl.DTLVardef@f26ae3_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2022

Autophagy protects against high-dose Mycobacterium tuberculosis infection

Host autophagy had been associated with the control of Mycobacterium tuberculosis (Mtb) infection due to its ability to sequesters microorganisms through a process termed "xenophagy"1-4. Xenophagy purportedly limits Mtb replication within infected macrophages1-4. However, studies in mice using a standard low-dose infection model demonstrated that xenophagy in infected phagocytes is not required to control Mtb pathogenesis5,6. Instead, an autophagy-independent function of ATG5 in myeloid cells controls low-dose Mtb infection through limiting neutrophilic inflammation5. Hitherto, an in vivo role for autophagy during Mtb infection remained to be elucidated. We report herein that autophagy in myeloid cells mediates protection against high-dose Mtb infection, providing the first evidence for a role for autophagy in myeloid cells during Mtb infection in vivo. With the exception of ATG5, the autophagy proteins required to control high-dose Mtb infection are dispensable for host defense against a standard low-dose Mtb infection. Specifically, autophagy is required in CD11c+ cells, but is dispensable in neutrophils, to control a high-dose Mtb infection in the lung. The role for autophagy is not to directly degrade Mtb in macrophages through xenophagy, but mainly to limit myeloid-derived suppressor cell accumulation and to promote sustained protective T cell responses. Together, our data highlight a novel role for autophagy in controlling Mtb infection, distinct from that of Atg5 during low-dose Mtb infection, or any previously reported roles for autophagy. In addition, our finding that the result of a pathogen-plus-susceptibility gene interaction is dependent on pathogen burden has important implications on our understanding of how Mtb infection in humans can lead to a spectrum of outcomes, the variables that contribute to autophagy gene function during infection and inflammation, and the potential use of autophagy modulators in clinical medicine.

microbiology↗