Endoplasmic Reticulum Stress and Renin-Angiotensin System Crosstalk in Endothelial Dysfunction.

BACKGROUND: Vascular endothelial dysfunction (VED) significantly results in catastrophic cardiovascular diseases with multiple aetiologies. Variations in vasoactive peptides, including angiotensin II and endothelin 1, and metabolic perturbations like hyperglycaemia, altered insulin signalling, and homocysteine levels result in pathogenic signalling cascades, which ultimately lead to VED. Endoplasmic reticulum (ER) stress reduces nitric oxide availability, causes aberrant angiogenesis, and enhances oxidative stress pathways, consequently promoting endothelial dysfunction. Moreover, the renin-angiotensin system (RAS) has widely been acknowledged to impact angiogenesis, endothelial repair and inflammation. Interestingly, experimental studies at the preclinical level indicate a possible pathological link between the two pathways in the development of VED. Furthermore, pharmacological modulation of ER stress ameliorates angiotensin-II mediated VED as well as RAS intervention either through inhibition of the pressor arm or enhancement of the depressor arm of RAS, mitigating ER stress-induced endothelial dysfunction and thus emphasizing a vital crosstalk. CONCLUSION: Deciphering the pathway overlap between RAS and ER stress may open potential therapeutic avenues to combat endothelial dysfunction and associated diseases. Several studies suggest that alteration in a component of RAS may induce ER stress or induction of ER stress may modulate the RAS components. In this review, we intend to elaborate on the crosstalk of ER stress and RAS in the pathophysiology of VED.

'PARP'ing fibrosis: repurposing poly (ADP ribose) polymerase (PARP) inhibitors.

Fibrosis is a wound-healing process that results in tissue scarring and organ dysfunction. Several novel mechanisms of fibrogenesis have been discovered recently. In this review, we focus on the role of poly-ADP ribose polymerase (PARP) in major organ fibrosis, such as lungs, heart, liver, and kidneys. PARP is a dynamic enzyme that modulates different cellular proteins by the addition of PAR groups and mediates an array of cellular events in both normal physiological and pathophysiological states. The US Food and Drug Administration (FDA) and European Medicines Agency (EMA) recently approved several PARP inhibitors, such as olaparib, niraparib, talazoparib, and rucaparib, for the treatment of ovarian and germline BRCA-mutant breast cancers. Consequently, repurposing these drugs could provide an opportunity to counter organ fibrosis.