2-Benzyllawsone protects against polymicrobial sepsis and vascular hyporeactivity in swiss albino mice

PVAT-induced aortic hypercontractility in acute sepsis: Role of ROS and COX-2 signaling

AIMS

Acute sepsis disrupts vascular tone through an exacerbated inflammatory response, leading to the release of vasodilatory substances such as nitric oxide and cyclooxygenase (COX)-derived prostanoids, primarily from the COX-2 isoform. These alterations may influence the anticontractile properties of perivascular adipose tissue (PVAT). This study investigated how acute sepsis affects PVAT's vasoactive profile and its role in vascular dysfunction.

MAIN METHODS

Thoracic aortas, with and without PVAT, were collected 6 h after cecal ligation and puncture (CLP)-induced sepsis. Vascular reactivity was assessed, reactive oxygen species (ROS) levels were measured using DHE staining, and GP91phox and COX expression were evaluated by immunofluorescence.

KEY FINDINGS

Acute sepsis caused significant aortic hyporeactivity in the absence of PVAT, which was reversed by PVAT, indicating a shift to a pro-contractile profile. This effect involved ROS, as shown by tiron's reversal of contraction. Inhibition of COX and blockade of vasocontractile COX metabolites, including thromboxane A2 and prostaglandin F2α, confirmed PVAT's COX-driven contractile activity during sepsis. Increased ROS bioavailability in septic PVAT was reduced by NADPH oxidase and COX-2 inhibitors. Immunostaining revealed increased GP91phox expression in septic PVAT and the adventitia, but COX-2 levels did not differ significantly between groups or layers.

SIGNIFICANCE

Our findings demonstrate that during acute sepsis, PVAT adopts a pro-contractile role mediated by ROS generation and cyclooxygenase-2-derived metabolites. This feedback loop may contribute to restoring vascular tone in sepsis, highlighting PVAT's significant role in modulating vascular function under pathological conditions.

Dehydroepiandrosterone (DHEA), a circulating steroid hormone precursor produced potent vasorelaxation in rat aorta and mesenteric arteries through blockade of L-type voltage-dependent calcium channels

Dehydroepiandrosterone (DHEA) is known for potent cardioprotective properties and diminished DHEA level in plasma is often associated with hypertension and age-related anomalies. However, putative ex-vivo vasorelaxation potential of DHEA in systemic resistance vessels like mesenteric arteries and conduit arteries like aorta are still to be worked out. The study aimed to explore vasorelaxation potential of DHEA in superior and resistance mesenteric arteries and aorta in rats and to determine the contribution L-type Voltage dependent calcium channel (L-VDCC) in the relaxation response in these arterial tissues. Ex-vivo vasorelaxation potential of DHEA in isolated arterial tissues were evaluated and the mechanism of vasorelaxation induced by DHEA was characterized by contraction experiment in isolated arterial tissue and in-vitro calcium imaging assay using Fluo-4 in primary vascular smooth muscle cells derived from aorta. In the current study, DHEA was found to exhibit potent concentration dependent, endothelium and potassium channel independent vasorelaxation response in conduit and resistance arteries. The block of L-type VDCCs was evident from the findings that DHEA in a concentration-dependent manner inhibited both BAY K-8644 and CaCl2-induced contractions. The results of the contraction experiment were further substantiated by Fluo-4 mediated calcium imaging assay in primary rat vascular smooth muscle wherein DHEA concentration dependently blocked noradrenaline and BAY K-8644-induced rise in intracellular calcium fluorescence. The present study showed potent endothelium and potassium channel independent vasorelaxation properties of DHEA in aorta, superior and resistance mesenteric artery mediated predominantly through blockade of L-VDCC.

The molecular biology and therapeutic potential of Nrf2 in leukemia

NF-E2-related factor 2 (Nrf2) transcription factor has contradictory roles in cancer, which can act as a tumor suppressor or a proto-oncogene in different cell conditions (depending on the cell type and the conditions of the cell environment). Nrf2 pathway regulates several cellular processes, including signaling, energy metabolism, autophagy, inflammation, redox homeostasis, and antioxidant regulation. As a result, it plays a crucial role in cell survival. Conversely, Nrf2 protects cancerous cells from apoptosis and increases proliferation, angiogenesis, and metastasis. It promotes resistance to chemotherapy and radiotherapy in various solid tumors and hematological malignancies, so we want to elucidate the role of Nrf2 in cancer and the positive point of its targeting. Also, in the past few years, many studies have shown that Nrf2 protects cancer cells, especially leukemic cells, from the effects of chemotherapeutic drugs. The present paper summarizes these studies to scrutinize whether targeting Nrf2 combined with chemotherapy would be a therapeutic approach for leukemia treatment. Also, we discussed how Nrf2 and NF-κB work together to control the cellular redox pathway. The role of these two factors in inflammation (antagonistic) and leukemia (synergistic) is also summarized.