Biology subjects

Porter, G.

Publications and source records attributed to Porter, G..

5 recordsLinked to original sources

bioRxiv2025

Lower Airway Dysbiosis in NTM+ Bronchiectasis is Associated with NET-Predominant Severe Phenotypes

RationaleThe discoveries of neutrophilic inflammation and Pseudomonas-dominant pulmonary dysbiosis have helped pave the way for host-directed therapy in bronchiectasis. Substantial knowledge gaps remain about the interplay between neutrophilic signatures and microbes in non-tuberculous mycobacterial lung disease (NTM-LD), a phenotypically diverse lung infection that is increasingly prevalent in the United States and other parts of the world. ObjectivesEvaluate the lower airway microbiota and neutrophilic traits in NTM- and NTM+ bronchiectasis. Methods16S rRNA gene sequencing, cell counts and neutrophil extracellular trap (NET) immunoassays were performed on bronchoscopic lower airway samples in 200 bronchiectasis subjects (108 NTM-, 92 NTM+). A preclinical model of oral commensal micro-aspiration and NTM infection was used to profile the murine lower airways with flow cytometry and a NET assay. Measurements and Main ResultsLower airways of NTM+ bronchiectasis patients were enriched with Mycobacterium and oral commensals (e.g., Veillonella, Prevotella). NET levels were higher in NTM+ BAL. Mycobacterium and oral commensals co-occurred with NET and neutrophils in network studies. Distinct oral commensal taxa associated with severe disease phenotypes such as cavitary disease and exacerbators. In a murine micro-aspiration model, the combination of oral commensals and Mycobacterium led to a sustained pro-inflammatory immune response marked by an increase in Th17, {gamma}8T cells, PD-1+ T lymphocytes as well as higher NET levels. ConclusionsOur analyses showed that distinct microbiome features beyond the primary pathogen can contribute to neutrophilic inflammation and severe disease phenotypes in bronchiectasis/ NTM-LD.

immunology↗

bioRxiv2025

Low Magnetic Fields Stimulate Cardiac Mitochondrial Bioenergetics with a Bell-Shaped Response: Possibly Via a Radical Pair Mechanism

Studies have shown that low magnetic fields (LMFs) of less than 1 x 10-3 Tesla (T) affect numerous biological events, including bacteria and plant growth, bird migration, and human brain activity. On a cellular level, LMFs affect ion channel activities, intracellular Ca2+ concentrations, and mitochondrial reactive oxygen species (mROS) generation. However, the mechanisms that could account for these effects are controversial. Here, we show that applying a static LMF, ranging from [~]2.7 x 10-4 to [~]1.9 x 10-3 T, to mitochondria isolated from adult rat hearts produced a bell-shaped increase in maximal respiration (Vmax) up to 40%. A similar LMF-induced increase in Vmax was also observed in mitochondria isolated from rat hearts subjected to ischemia-reperfusion (I-R) injury. We then obtained data showing that LMF- mediated bell-shaped response was also observed in the activity of several enzymes involved in oxidative phosphorylation (OXPHOS), including Complexes II, III, and V, and citrate synthase. By contrast, similar LMF caused little change in the enzymatic activity of Complex I. Interestingly, mROS generation responded to LMF with an inverted bell-shaped decrease. We propose a radical pair mechanism of magnetoreception in cytochromes, catalytical reactions, and iron-sulfur clusters within the OXPHOS enzymes to explain how an LMF can increase the likelihood of electron spin transitions from singlet to triplet state and reverse it as the magnetic field strength further increases, resulting in a bell-shaped response. Our results indicate that a narrow range of LMF can enhance mitochondrial bioenergetics and decrease mROS. This may provide a non-invasive approach to treating diseases, such as I-R injury, when energy generation is compromised and oxidative stress is magnified.

biophysics↗

bioRxiv2021

Transcriptional regulation of cyclophilin D by BMP/SMAD signaling and its role in osteogenic differentiation

Cyclophilin D (CypD) promotes opening of the mitochondrial permeability transition pore (MPTP) which plays a key role in both cell physiology and pathology. It is, therefore beneficial for cells to tightly regulate CypD and MPTP but little is known about such regulation. We have reported before that CypD is downregulated and MPTP deactivated during differentiation in various tissues. Herein, we identify BMP/Smad signaling, a major driver of differentiation, as a transcriptional repressor of the CypD gene, Ppif. Using osteogenic induction of mesenchymal lineage cells as a model of BMP/Smad-dependent differentiation, we show that CypD is in fact transcriptionally repressed during this process. The importance of such CypD downregulation is evidenced by the negative effect of CypD rescue via gain-of-function on osteogenesis both in vitro and in vivo. In sum, we characterized BMP/Smad signaling as a regulator of CypD expression and elucidated the role of CypD downregulation during cell differentiation.

cell biology↗

bioRxiv2021

TNF signalling fine-tunes Langerhans cell transcriptional programmes mediating adaptive immunity.

Langerhans cells (LCs) reside in the epidermis as a dense network of immune system sentinels, coordinating both immunogenic and tolerogenic immune responses. To determine molecular switches directing induction of LC immune activation, we performed mathematical modelling of gene regulatory networks identified by single cell RNA sequencing of LCs exposed to TNF, a key pro-inflammatory signal produced by the skin. Our approach delineated three programmes of LC phenotypic activation (immunogenic, tolerogenic or ambivalent), and confirmed that TNF enhanced LC immunogenic programming. Through regulon analysis followed by mutual information modelling, we identified IRF1 as the key transcription factor for the regulation of immunogenicity in LCs. Application of a mathematical toggle switch model, coupling IRF1 with tolerance-inducing transcription factors, determined the key set of transcription factors regulating the switch between tolerance and immunogenicity, and correctly predicted LC behaviour in LCs derived from different body sites. Our findings provide a mechanistic explanation of how combinatorial interactions between different transcription factors can coordinate specific transcriptional programmes in human LCs, interpreting the microenvironmental context of the local tissue microenvironments.

systems biology↗

bioRxiv2019

Single cell transcriptomic analysis identifies Langerhans cells immunocompetency is critical for IDO1- dependent ability to induce tolerogenic T cells.

Human epidermal Langerhans cells (LCs) can coordinate both immunogenic and tolerogenic immune responses, creating an attractive opportunity for immunomodulation strategies. To investigate transcriptional determinants of human primary LC tolerance we applied single cells RNA-sequencing combined with transcriptional network modelling and functional analysis. Unsupervised clustering of single cell transcriptomes revealed that steady-state LCs exist in immature and immunocompetent states, and become fully immunocompetent on migration. Interestingly, LC migration, which has been shown to result in upregulation of the transcription factor IRF4, led in parallel to increased expression of a tolerogenic gene module including IDO1, LGALS1, LAMTOR1 and IL10RA, which translated to efficient induction of regulatory T cells in co-culture assays by immunocompetent LCs. Using protein expression analysis and perturbation with inhibitors, we confirmed the role of IDO1 as a mediator of LC tolerogenic responses induced during LC migration. Computational analysis of regulons and Partial Information Decomposition analyses identified IRF4 as a key driver for LC tolerogenic programmes. The predicted IRF4-regulated genes were confirmed by analysis of CRISPR-Cas9 edited LCs. These findings suggest that efficient priming of tolerogenic responses by LCs requires upregulation of a migration-coupled maturation program which is superimposed with a tolerance-inducing genomic module.

systems biology↗