Biology subjects

Lazrak, A.

Publications and source records attributed to Lazrak, A..

5 recordsLinked to original sources

bioRxiv2024

Oxidative Injury to Lung Mitochondrial DNA is a Key Contributorfor the Development of Chemical Lung Injury

The mechanisms and extent to which inhalation of oxidant gases damage the mitochondrial genome contributing to the development of acute and chronic lung injury have not been investigated. C57BL/6 mice exposed to chlorine (Cl2) gas and returned to room air, developed progressive loss of lung DNA glycosylase OGG1, significant oxidative injury to mtDNA, decreased intact lung mitochondrial (mt) DNA, generation of inflammatory pathway by DAMPs causing airway and alveolar injury with significant mortality. Global proteomics identified over 1400 lung proteins with alteration of key mitochondrial proteins at 24 h post Cl2 exposure. Intranasal instillation of a recombinant protein containing mitochondrial targeted OGG1 (mitoOGG1) post exposure, decreased oxidative injury to mtDNA, lung mitochondrial proteome, severity of the acute and chronic lung injury and increased survival. These data show that injury to the mt-genome is a key contributor to the development of acute and chronic lung injury.

physiology↗

bioRxiv2023

Leucine zipper-based sorting system enables generation of multi-functional CAR T cells

Resistance to chimeric antigen receptor (CAR) T cell therapy develops through multiple mechanisms including antigen-loss escape and tumor-induced immune suppression. Expression of multiple CARs may overcome multi-antigen-loss escape. Similarly, expression of switch receptors that convert inhibitory immune checkpoint signals into positive costimulatory signals may enhance CAR T cell activity in the tumor microenvironment. Engineering multiple features into one cell product, however, is limited by transgene packaging constraints of current vector systems. Here, we describe a leucine zipper-based cell sorting methodology that enables selective single-step immunomagnetic purification of cells co-transduced with two vectors, designed to potentially double the number of incorporated transgenes. This "Zip-sorting" system facilitated generation of T cells simultaneously expressing up to four CARs and co-expressing up to three switch receptors. These multi-CAR multi-Switch receptor arrays enabled T cells to eliminate antigenically heterogeneous syngeneic leukemia populations co-expressing multiple inhibitory ligands. Zip-sorted multi-CAR multi-Switch receptor T cells represent a potent therapeutic strategy to overcome multiple mechanisms of CAR T cell resistance.

synthetic biology↗

bioRxiv2022

Low Molecular Weight Hyaluronan Inhibits Lung Epithelial Ion Channels by Activating Calcium-Sensing Receptor

Herein, we tested the hypothesis low molecular weight hyaluronan (LMW-HA) inhibits lung epithelial ion transport in-vivo, ex-vivo, and in-vitro by activating the calcium-sensing receptor (CaSR). Intranasal instillation of LMW-HA (150g/ml) to C57BL/6 mice inhibited their alveolar fluid clearance (AFC) by 75%, increased the epithelial lining fluid (ELF) thickness threefold, and lung wet/dry (W/D) ratio by 20% 24hrs later. Incubation of lung slices from mouse and human lungs with 150g/ml LMW-HA decreased the open probability (Po) of ENaC in ATII cell by more than 50% in 4hrs, inhibited amiloride sensitive short circuit current (SCC) 4hrs post exposure, and Cl- current through CFTR by more than 70%, and Na,K-ATPase current by 66% at 24hrs. In all cases the inhibitory effect of LMW-HA on lung epithelial ion transport in vivo, ex vivo, and in vitro preparations were reversed by the administration of 1M of NPS2143, a CaSR inhibitor, or 150g/ml HMW-HA. In HEK-293 cells co-transfected with CaSR and the calcium sensitive Cl- channel TMEM16-A, LMW-HA activated an inward Cl- current. These data are the first demonstration of the inhibitory effects of LMW-HA on lung epithelial ion and water transport, and are due to the activation of CaSR and its downstream signaling cascades.

physiology↗

bioRxiv2021

Dynamic structural cell responses in the thymus to acute injury, regeneration, and age

The thymus is essential for establishing adaptive immunity yet undergoes age-related atrophy leading to compromised immune responsiveness. The thymus is also extremely sensitive to acute insult and although capable of regeneration, this capacity declines with age. Focusing on non-hematopoietic stromal cells, and using single-cell and spatial transcriptomics, lineage-tracing, and advanced imaging, we discovered two atypical thymic epithelial cell (TEC) states that emerged with age. Age-associated (aa)TECs formed atypical high-density epithelial clusters that were devoid of thymocytes, an accretion of non-functional thymic tissue that worsened with age and exhibited features of partial epithelial-to-mesenchymal transition (EMT). In silico interaction analysis revealed that aaTEC emergence drew tonic signals from other TEC populations at baseline, acting as a sink for TEC growth factors. Following damage, aaTEC expanded substantially, further perturbing trophic pathways, and correlating with defective regeneration of the involuted thymus. These findings define a unique feature of thymic involution linked to immune aging.

immunology↗

bioRxiv2020

Heme Impairs Alveolar Epithelial Sodium Channels Post Toxic Gas Inhalation

We previously reported that cell-free heme (CFH) is increased in the plasma of patients with acute and chronic lung injury and causes pulmonary edema in animal model of acute respiratory distress syndrome (ARDS) post inhalation of halogen gas. However, the mechanisms by which CFH causes pulmonary edema are unclear. Herein we report for the first time the presence of CFH and chlorinated lipids (formed by the interaction of halogen gas, Cl2, with plasmalogens) in the plasma of patients and mice exposed to Cl2 gas. Ex vivo incubation of red blood cells (RBC) with halogenated lipids caused oxidative damage to RBC cytoskeletal protein spectrin, resulting in hemolysis and release of CFH. A single intramuscular injection of the heme-scavenging protein hemopexin (4 {micro}g/kg body weight) in mice, one hour post halogen exposure, reversed RBC fragility and decreased CFH levels to those of air controls. Patch clamp and short circuit current measurements revealed that CFH inhibited the activity of amiloride-sensitive (ENaC) and cation sodium (Na+) channels in mouse alveolar cells and trans-epithelial Na+ transport across human airway cells with EC50 of 125 nM and 500 nM, respectively. Molecular modeling identified 22 putative heme-docking sites on ENaC (energy of binding range: 86-1563 kJ/mol) with at least 2 sites within its narrow transmembrane pore, potentially capable of blocking Na+ transport across the channel. In conclusion, results suggested that CFH mediated inhibition of ENaC activity may be responsible for pulmonary edema post inhalation injury.

physiology↗