Biology subjects

Maddox, M.

Publications and source records attributed to Maddox, M..

3 recordsLinked to original sources

bioRxiv2025

Transcriptional Regulator, Metabolic, and Pilus Biosynthesis Genes as Candidate Virulence Markers in High-Virulence Mycobacterium abscessus

Mycobacterium abscessus is a rapidly growing non-tuberculosis mycobacterium that opportunistically causes pulmonary infections and is notable for its high resistance to antibiotics. While ubiquitous in environmental reservoirs such as soil, water, and biofilms, the genetic factors that enable certain strains to invade and persist in human hosts have remained elusive. To address this gap, we compared whole-genome sequences from 45 environmental isolates-- primarily collected on Hawaii Island--with a globally sourced set of clinical isolates retrieved from NCBI RefSeq. Our phylogenetic reconstruction delineated environmental and clinical lineages, and pangenome profiling revealed a conserved core genome of approximately 4,800 genes alongside a large accessory genome. Crucially, we found 20 genes conserved in clinical isolates, but not environmental isolates. Clinical isolates were found to have conserved genes coding for erm(41), three transcriptional regulators, a pilus synthesis gene, an NADP-dependent oxidoreductase, a carbonic anhydrase, a probable L-ectoine synthase, a ribonuclease P protein component, and 11 hypothetical genes, whereas environmental isolated did not conserve any of these genes. This indicates that clinical isolates have undergone broad changes relating to metabolism, pilus biosynthesis, and transcriptional regulators, which may be necessary for pathogenicity. The candidate virulence markers uncovered here lay the groundwork for experimental validation, rapid diagnostics for non-tuberculous mycobacteria, and targeted surveillance of environmental reservoirs to mitigate the emergence of clinically significant strains. ImportanceMycobacterium abscessus is an emerging pathogen that causes pulmonary infections in susceptible individuals. Though currently an opportunistic pathogen, M. abscessus may be undergoing evolutionary changes to become an obligate pathogen. Because of this, there is the need to identify markers of virulence in M. abscessus in order to better screen isolates and assess their risk of causing infection. This also provides the opportunity to study a similar pathogenesis to what Mycobacterium tuberculosis may have undergone. This study revealed that clinical isolates of M. abscessus have conserved genes relating to pilus biosynthesis, metabolism, and transcriptional regulators that environmental isolates do not have. These conserved genes may be required for M. abscessus to acquire virulence, and these genes have potential use as biomarkers to screen isolates for possible pathogenicity.

microbiology↗

bioRxiv2024

Quinolinic acid links kidney injury to brain toxicity

Kidney dysfunction often leads to neurological impairment, yet the complex kidney-brain relationship remains elusive. We employed spatial and bulk metabolomics to investigate a mouse model of rapid kidney failure induced by mouse double minute 2 (Mdm2) conditional deletion in the kidney tubules to interrogate kidney and brain metabolism. Pathway enrichment analysis of focused plasma metabolomics panel pinpointed tryptophan metabolism as the most altered pathway with kidney failure. Spatial metabolomics showed toxic tryptophan metabolites in the kidneys and brains, revealing a novel connection between advanced kidney disease and accelerated kynurenine degradation. In particular, the excitotoxic metabolite quinolinic acid was localized in ependymal cells adjacent to the ventricle in the setting of kidney failure. These findings were associated with brain inflammation and cell death. A separate mouse model of acute kidney injury also had an increase in circulating toxic tryptophan metabolites along with altered brain inflammation. Patients with advanced CKD similarly demonstrated elevated plasma kynurenine metabolites and quinolinic acid was uniquely correlated with fatigue and reduced quality of life in humans. Overall, our study identifies the kynurenine pathway as a bridge between kidney decline, systemic inflammation, and brain toxicity, offering potential avenues for diagnosis and treatment of neurological issues in kidney disease.

molecular biology↗

bioRxiv2024

Targeting PD-L1 in solid cancer with myeloid cells expressing a CAR-like immune receptor

Myeloid cells are prevalent in solid cancers, but they frequently exhibit a pro-tumor phenotype, hindering cancer immunotherapy. Their abundance makes engineered myeloid cell therapy an intriguing approach to tackle challenges posed by solid cancers, such as tumor trafficking and infiltration along with tumor cell heterogenicity and immunosuppressive tumor microenvironment (TME). Solid cancers often upregulate the checkpoint molecule PD-L1 to evade immune responses. Thus, we devised an adoptive cell therapy strategy based on myeloid cells expressing a Chimeric Antigen Receptor (CAR)-like immune receptor (CARIR). The extracellular domain of CARIR is derived from the natural inhibitory receptor PD-1, while the intracellular domain(s) are derived from CD40 and/or CD3{xi}. To assess the efficacy of CARIR-engineered myeloid cells, we conducted proof-of-principle experiments using co-culture and flow cytometry-based phagocytosis assays in vitro. Additionally, we employed a fully immune-competent syngeneic tumor mouse model to evaluate the strategys effectiveness in vivo. Co-culturing CARIR-expressing human monocytic THP-1 cells with PD-L1+ target cells lead to upregulation of the co-stimulatory molecule CD86 along with expression of proinflammatory cytokines TNF-1 and IL-1{beta}. Moreover, CARIR expression significantly enhanced phagocytosis of multiple PD-L1+ human solid tumor cell lines in vitro. Similar outcomes were observed with CARIR-expressing human primary macrophages. In experiments conducted on Balb/c mice bearing aggressive 4T1 mammary tumors, infusing murine myeloid cells expressing a murine version of CARIR significantly slowed tumor growth and prolonged survival. Taken together, our results demonstrate that adoptive transfer of PD-1 CARIR-engineered myeloid cells may be an effective strategy in treating PD-L1+ solid tumors. Graphic Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=105 SRC="FIGDIR/small/577873v1_ufig1.gif" ALT="Figure 1"> View larger version (15K): org.highwire.dtl.DTLVardef@1657eborg.highwire.dtl.DTLVardef@e61ae3org.highwire.dtl.DTLVardef@ef3df4org.highwire.dtl.DTLVardef@cc90ea_HPS_FORMAT_FIGEXP M_FIG C_FIG In BriefWe described here an adoptive cell therapy approach employing PD-L1-specific CAR-like immune receptor (CARIR) modified myeloid cells as a potential immune cell therapy strategy for treating PD-L1+ solid cancer. O_LICARIR expression directed human THP-1 macrophages to recognize PD-L1+ target cells, which led to an upregulation of co-stimulatory molecule CD86 and production of proinflammatory cytokines TNF- and IL-1{beta}. C_LIO_LICARIR expression in human THP-1 macrophages had increased % phagocytosis and killing against PD-L1+ tumor cells in vitro. C_LIO_LIAdoptive transfer of CARIR transduced myeloid cells in immunocompetent syngeneic mice with established aggressive 4T1 tumor significantly slowed tumor growth and prolonged survival. C_LI

immunology↗