Biology subjects

Connelly, C.

Publications and source records attributed to Connelly, C..

5 recordsLinked to original sources

bioRxiv2023

Male pathology regardless of behaviour drives transmission in an avian host-pathogen system

Host sex is an important source of heterogeneity in the severity of epidemics. Pinpointing the mechanisms causing this heterogeneity can be difficult because differences in behaviour among sexes (e.g. greater territorial aggression in males) can bias exposure risk, obfuscating the role of immune function, which can lead to differences in pathology, in driving differential susceptibility between sexes. Thus, sex-biased transmission driven by differences in immune function independent of behaviour is poorly understood, especially in non-mammalian systems. Here we examine the previously unexplored potential for male-biased pathology to affect transmission using an avian host-pathogen system. We employ a sex-dependent multistate transmission model parameterized with isolated, individual-based experimental exposures of domestic canaries and experimental transmission data of house finches. The experiment revealed that male birds have shorter incubation periods, longer recovery periods, higher pathogen burdens, and greater disease pathology, than females. Our model revealed that male-biased pathology led to epidemic size rapidly increasing with the proportion of male birds, with a nearly 16-fold increase in total epidemic size from an all-female to an all-male simulation. Our results demonstrate that female-biased resistance, independent of male behaviour, can drive sex-dependent transmission in wildlife, indicating that sex-based differences in immune function, not just differences in exposure risk, can shape epidemic dynamics.

ecology↗

bioRxiv2023

GDF15 is a dynamic biomarker of the Integrated Stress Response in the central nervous system

AimCharacterize Growth Differentiation Factor 15 (GDF15) as a secreted biomarker of the Integrated Stress Response (ISR) within the Central Nervous System (CNS). MethodsWe determined GDF15 levels utilizing in vitro and in vivo neuronal systems wherein the ISR was activated. Primarily, we used the murine model of Vanishing White Matter disease (VWMD), a neurological disease driven by persistent ISR in the CNS, to establish a link between levels of GDF15 in the cerebrospinal fluid (CSF) and ISR gene expression signature in the CNS. GDF15 was also determined in the CSF of VWM patients. ResultsGDF15 expression was increased concomitant to ISR activation in stress-induced primary astrocytes as well as in retinal ganglion cells following optic nerve crush, while treatment with 2Bact, a specific eIF2B activator, suppressed both the ISR and GDF15. In the VWMD model, CSF GDF15 levels corresponded with the magnitude of the ISR and were reduced by 2BAct. In VWM patients, mean CSF GDF15 was elevated >20-fold as compared to healthy controls, whereas plasma GDF15 was undifferentiated. ConclusionsThese data suggest that CSF GDF15 is a dynamic marker of ISR activation in the CNS and may serve as a pharmacodynamic biomarker for ISR-modulating therapies.

neuroscience↗

bioRxiv2023

Disruption of Prostaglandin F2α Receptor Signaling Attenuates Fibrotic Remodeling and Alters Fibroblast Population Dynamics in A Preclinical Murine Model of Idiopathic Pulmonary Fibrosis

Idiopathic Pulmonary Fibrosis (IPF) is a chronic parenchymal lung disease characterized by repetitive alveolar cell injury, myofibroblast proliferation, and excessive extracellular matrix deposition for which unmet need persists for effective therapeutics. The bioactive eicosanoid, prostaglandin F2, and its cognate receptor FPr (Ptfgr) are implicated as a TGF{beta}1 independent signaling hub for IPF. To assess this, we leveraged our published murine PF model (IER -SftpcI73T) expressing a disease-associated missense mutation in the surfactant protein C (Sftpc) gene. Tamoxifen treated IER -Sftpc I73T mice develop an early multiphasic alveolitis and transition to spontaneous fibrotic remodeling by 28 days. IER -Sftpc I73T mice crossed to a Ptgfr null (FPr-/-) line showed attenuated weight loss and gene dosage dependent rescue of mortality compared to FPr+/+ cohorts. IER -Sftpc I73T /FPr-/- mice also showed reductions in multiple fibrotic endpoints for which administration of nintedanib was not additive. Single cell RNA sequencing, pseudotime analysis, and in vitro assays demonstrated Ptgfr expression predominantly within adventitial fibroblasts which were reprogrammed to an "inflammatory/transitional" cell state in a PGF2/ FPr dependent manner. Collectively, the findings provide evidence for a role for PGF2 signaling in IPF, mechanistically identify a susceptible fibroblast subpopulation, and establish a benchmark effect size for disruption of this pathway in mitigating fibrotic lung remodeling.

molecular biology↗

bioRxiv2020

PKR and the Integrated Stress Response drive immunopathology caused by ADAR1 mutation

Mutations in ADAR, the gene that encodes the ADAR1 RNA deaminase, cause numerous human diseases, including Aicardi-Goutieres Syndrome (AGS). ADAR1 is an essential negative regulator of the RNA sensor MDA5, and loss of ADAR1 function triggers inappropriate activation of MDA5 by self-RNAs. However, the mechanisms of MDA5-dependent disease pathogenesis in vivo remain unknown. Here, we introduce a knockin mouse that models the most common ADAR AGS mutation in humans. These Adar-mutant mice develop lethal disease that requires MDA5, the RIG-I-like receptor LGP2, type I interferons, and the eIF2 kinase PKR. We show that a small molecule inhibitor of the integrated stress response (ISR) that acts downstream of eIF2 phosphorylation prevents immunopathology and rescues the mice from mortality. These findings place PKR and the ISR as central components of immunopathology in vivo and identify new therapeutic targets for treatment of human diseases associated with the ADAR1-MDA5 axis.

immunology↗

bioRxiv2017

BRD4 inhibitors block telomere elongation

Cancer cells maintain telomere length equilibrium to avoid senescence and apoptosis induced by short telomeres, which are triggered by the DNA damage response. Limiting the potential for telomere maintenance in cancer cells has been long been proposed as a therapeutic target. Using an unbiased shRNA screen targeting known kinases, we identified bromodomain 4 (BRD4) as a telomere length regulator. Four independent BRD4 inhibitors blocked telomere elongation, in a dose dependent manner, in mouse cells overexpressing telomerase. Long-term treatment with BRD4 inhibitors caused telomere shortening in both mouse and human cells, suggesting BRD4 plays a role in telomere maintenance in vivo. Telomerase enzymatic activity was not directly affected by BRD4 inhibition. BRD4 is in clinical trials for a number of cancers, but its effects on telomere maintenance have not been previously reported investigated.

molecular biology↗