The role of peroxisome proliferator-activated receptors in the modulation of hyperinflammation induced by SARS-CoV-2 infection: A perspective for COVID-19 therapy.

Coronavirus disease 2019 (COVID-19) is a severe respiratory disease caused by infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that affects the lower and upper respiratory tract in humans. SARS-CoV-2 infection is associated with the induction of a cascade of uncontrolled inflammatory responses in the host, ultimately leading to hyperinflammation or cytokine storm. Indeed, cytokine storm is a hallmark of SARS-CoV-2 immunopathogenesis, directly related to the severity of the disease and mortality in COVID-19 patients. Considering the lack of any definitive treatment for COVID-19, targeting key inflammatory factors to regulate the inflammatory response in COVID-19 patients could be a fundamental step to developing effective therapeutic strategies against SARS-CoV-2 infection. Currently, in addition to well-defined metabolic actions, especially lipid metabolism and glucose utilization, there is growing evidence of a central role of the ligand-dependent nuclear receptors and peroxisome proliferator-activated receptors (PPARs) including PPARα, PPARß/δ, and PPARγ in the control of inflammatory signals in various human inflammatory diseases. This makes them attractive targets for developing therapeutic approaches to control/suppress the hyperinflammatory response in patients with severe COVID-19. In this review, we (1) investigate the anti-inflammatory mechanisms mediated by PPARs and their ligands during SARS-CoV-2 infection, and (2) on the basis of the recent literature, highlight the importance of PPAR subtypes for the development of promising therapeutic approaches against the cytokine storm in severe COVID-19 patients.

The Promising Effect of Colchicine on Random-Pattern Skin Flap Survival in Rats: Glutamate Pathway.

BACKGROUND: Random-pattern skin flap is a conventional procedure in reconstructive surgery, yet partial or complete flap necrosis has remained a major issue. Herein, we investigated the potential effects of colchicine on skin flap survival through the glutamate pathway and N-methyl-D-aspartate (NMDA) receptors. METHODS: Wistar male rats were injected multiple doses of colchicine intraperitoneally (0.02, 0.05, 0.1, and 0.4 mg/kg) before the surgery. MK-801 (a noncompetitive NMDA receptor antagonist) was administered in combination with colchicine to assess the role of glutamate. Histopathological evaluation; quantitative assessment of glutamate, IL-6, and TNF-α; and the expression of NR2A-type NMDA receptors were performed in the skin tissue. RESULTS: Colchicine 0.05 mg/kg could significantly promote flap survival compared to the control group (P < 0.001), while administration of MK-801 (0.05 mg/kg) reversed the effect of colchicine (0.05 mg/kg) (P < 0.001). Levels of IL-6 and TNF-α decreased, and the expression of NR2A-type NMDA receptors was enhanced in the flap tissue of colchicine 0.05 mg/kg group compared to the controls. Also, glutamate level significantly increased after the administration of colchicine 0.05 mg/kg compared to the controls (P < 0.05). CONCLUSIONS: We found that colchicine could improve skin flap survival remarkably in rats that have undergone skin flap surgery through the glutamate pathway and NMDA receptors.

The Evaluation of the Neuroprotective Effect of a Single High-Dose Vitamin D3 in Patients with Moderate Ischemic Stroke.

INTRODUCTION: Vitamin D insufficiency is highly prevalent and is a negative predictor for survival in ischemic stroke patients. We evaluated the effect of a high dose of vitamin D3 on the Neuron-Specific Enolase (NSE) level, National Institute of Health Stroke Scale (NIHSS), and Barthel Index (BI) scoring system in moderate ischemic stroke patients. METHODS: This prospective, double-blind, randomized clinical trial (RCT) study was conducted from April 2020 to March 2021. Patients with moderate ischemic stroke (NIHSS 5 to 15) who had vitamin D deficiency (serum 25-OH vitamin D ≤30 ng/mL) were recruited and randomized into intervention and control groups. Subjects in the intervention group received a single dose, intramuscular (IM) injection of 600000 international unit (IU) vitamin D3, in addition to the standard treatment. NSE level and NIHSS were evaluated at baseline and 48 hours after the intervention. The BI was monitored three months after discharge. RESULTS: During the study period, 570 patients were assessed; finally, forty-one patients completed the study. Except for the age which was higher in the control group (p = 0.04), there were no statistically significant differences in other baseline characteristics between the two groups. After 48 hours, the NIHSS score was significantly lower in the intervention group (median 8 vs. 6.5, p = 0.008 in the control and intervention groups, respectively), but there was no significant difference in the NSE level (p = 0.80). Three months after discharge, the BI was significantly higher in the intervention group (median 8 vs. 9, p = 0.03 in the control and intervention groups, respectively). CONCLUSIONS: Administration of a single 600000 IU of vitamin D3 could have neuroprotective effects in patients with moderate ischemic stroke, according to its significantly positive effects on functional clinical outcomes (NIHSS and BI), but this effect on the biomarker related to neural damage (NSE) was not significant.

Anti-inflammatory Effects of Ivermectin in the Treatment of Acetic Acid-Induced Colitis in Rats: Involvement of GABAB Receptors.

BACKGROUND: Recent investigations have proposed the potential role of gamma-aminobutyric acid (GABA) in regulating motility and immunity of the gastrointestinal system. AIMS: We aimed to investigate the anti-inflammatory effects of ivermectin (IVM) through GABAB receptors following acetic acid-induced colitis in rats. METHODS: In a controlled experimental study, we enrolled 78 male Wistar rats (13 groups; 6 rats/group). After colitis induction using acetic acid (4%), IVM, baclofen (a standard GABAB agonist) or the combination of both agents was delivered to rats orally (by gavage), with the same dosage continued for 5 days. The control group received the vehicle, and prednisolone (a standard anti-inflammatory agent) was administered in a separate group as the positive control. Colon samples were collected on the sixth day for histopathological evaluations and measurement of myeloperoxidase (MPO) activity, TNF-α levels, and p-NF-ĸB p65, COX-2 and iNOS expression levels. RESULTS: The greatest recovery was found after administering IVM 0.5, baclofen 0.5, or IVM 0.2 + baclofen 0.2 mg/kg/day (ulcer index [UI] = 1.4 ± 0.4, 1.7 ± 0.6, and 1.4 ± 0.3, respectively; p < 0.001 vs. the control [UI = 6.5 ± 0.7]). Histopathological evaluations revealed a significant decrease in the inflammation severity in the three above-mentioned groups. P-NF-ĸB p65, COX-2, and iNOS expression, MPO activity, and TNF-α levels also decreased dramatically following treatment with IVM 0.5, baclofen 0.5, or the combination therapy (p < 0.001 vs. the control). CONCLUSIONS: IVM exerted promising anti-inflammatory effects in treating acetic acid-induced colitis in rats. Its synergistic effect with baclofen also signified the possible involvement of GABAB receptors in this process.