Apocynin is a naturally occurring methoxy‐substituted catechol, experimentally used as an inhibitor of NADPH‐oxidase. It can decrease the production of superoxide () from activated neutrophils and macrophages while the ability of phagocytosis remains unaffected. The anti‐inflammatory activity of apocynin has been demonstrated in a variety of cell and animal models of inflammation. Apocynin, after metabolic conversion, inhibits the assembly of NADPH‐oxidase that is responsible for reactive oxygen species (ROS) production. It is, therefore, extensively used to reveal the role of this enzyme in cell and experimental models. Although some of the ROS serve as signaling molecules in the cells, excessive production is damaging and has been implicated to play an important role in the progression of many disease processes. This is why in many studies apocynin presents a promising potential treatment for some disorders; however, its utility with inflammatory diseases remains to be determined. Since its mode of action is not well defined, we tried to get a more precise insight into the mechanisms by which apocynin exerts its activity. Considering the anti‐inflammatory activities of apocynin, we may conclude that this compound definitely deserves further study.

The mechanism of aspirin (acetylsalicylic acid [ASA]) sensitivity associated with severe asthma and chronic rhinosinusitis with nasal polyps (“aspirin triad”) has been attributed to arachidonic metabolism alternations, although the putative biochemical defects have not been elucidated. The aim of this study was assessment of the hypothesis that local production of eicosanoids in the respiratory epithelium in patients with ASA-sensitive asthma/rhinosinusitis (ASARS) differs from that of ASA-tolerant patients with rhinosinusitis (ATRS). Nasal polyps were obtained from 10 patients with ASARS and 15 with ATRS during routine polypectomies, and epithelial cells (ECs) were cultured on bovine collagen type I matrix (Vitrogen 100), in medium supplemented with growth factors. The generation of eicosanoids in supernatants of confluent ECs (6 to 8 d of culture; purity > 98%) was quantified by immunoassays. Unstimulated ECs from ASARS patients generated significantly less prostaglandin E2(PGE2) compared with ATRS (0.8 ± 0.3 versus 2.4 ± 0.5 ng/ μ g double-stranded deoxyribonucleic acid [dsDNA], respectively), although a similar relative increase in response to calcium ionophore and inhibition with ASA was observed in both groups. Basal levels of 15-hydroxyeicosatetraenoic acid (15-HETE) were not different between groups, and calcium ionophore enhanced its production to a similar extent. However, cells incubation with 200 μ M ASA for 60 min resulted in a significant increase (mean + 359%) in 15-HETE generation only in ASARS patients, whereas no effect of ASA on 15-HETE generation in ATRS patients was observed. PGF2 α generation was similar in both groups, and no significant generation of PGD2 or leukotriene C4 (LTC4) was observed in epithelial cell cultures from either group. Our results indicate that nasal polyps ECs from ASA-sensitive patients have significant abnormality in basal and ASA-induced generation of eicosanoids which may be causally related to the mechanism of ASA sensitivity. Kowalski ML, Pawliczak R, Wozniak J, Siuda K, Poniatowska M, Iwaszkiewicz J, Kornatowski T, Kaliner MA. Differential metabolism of arachidonic acid in nasal polyp epithelial cells cultured from aspirin-sensitive and aspirin-tolerant patients.

Probiotics are defined as live microorganisms that have a beneficial effect on health by exhibiting quantitative and qualitative effects on intestinal microflora and/or modification of the immune system. A strain is considered probiotic if it demonstrates a series of clinically proven health...

The COVID‐19 pandemic caused relatively high mortality in patients, especially in those with concomitant diseases (i.e., diabetes, hypertension, and chronic obstructive pulmonary disease (COPD)). In most of aforementioned comorbidities, the oxidative stress appears to be an important player in their pathogenesis. The direct cause of death in critically ill patients with COVID‐19 is still far from being elucidated. Although some preliminary data suggests that the lung vasculature injury and the loss of the functioning part of pulmonary alveolar population are crucial, the precise mechanism is still unclear. On the other hand, at least two classes of medications used with some clinical benefits in COVID‐19 treatment seem to have a major influence on ROS (reactive oxygen species) and RNS (reactive nitrogen species) production. However, oxidative stress is one of the important mechanisms in the antiviral immune response and innate immunity. Therefore, it would be of interest to summarize the data regarding the oxidative stress in severe COVID‐19. In this review, we discuss the role of oxidative and antioxidant mechanisms in severe COVID‐19 based on available studies. We also present the role of ROS and RNS in other viral infections in humans and in animal models. Although reactive oxygen and nitrogen species play an important role in the innate antiviral immune response, in some situations, they might have a deleterious effect, e.g., in some coronaviral infections. The understanding of the redox mechanisms in severe COVID‐19 disease may have an impact on its treatment.

The aim of the present study was to assess whether probiotic bacteria Lactobacillus casei (4 × 10⁸ CFU) influences the antioxidant properties of human plasma when combined with prebiotic Inulin (400 mg). Experiments were carried out on healthy volunteers (n = 32). Volunteers were divided according to sex (16 male and 16 female) and randomly assigned to synbiotic and control groups. Blood samples were collected before synbiotic supplementation and after 7 weeks, at the end of the study. Catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) activity, and the ferric reducing ability of plasma (FRAP) in human plasma were examined. The administration of synbiotics containing L. casei plus Inulin resulted in a significant increase in FRAP values (p = 0.00008) and CAT activity (p = 0.02) and an insignificant increase in SOD and GPx activity compared to controls. Synbiotics containing L. casei (4 × 10⁸ CFU) with prebiotic Inulin (400 mg) may have a positive influence on human plasma antioxidant capacity and the activity of selected antioxidant enzymes.