[Role of Mitochondria in Intestinal Epithelial Barrier Dysfunction in Inflammatory Bowel Disease].

Inflammatory bowel disease (IBD) is widespread in industrial countries with every 20th citizen being affected. Dysregulation of the epithelial barrier function is considered to play a key role in IBD. Permeability of the intestinal epithelium depends mostly on its self-renewal potential and the condition of intercellular junctions. Mitochondria are involved in regulating various intracellular processes in addition to their energy function. Recent data implicate mitochondria in intestinal epithelial barrier regulation and IBD. Mitochondrial dysfunction is possibly one of the factors that underlie the structural abnormalities of tight junctions and the cytoskeleton in intestinal epithelial cells and decrease the self-renewal capacity of the epithelium. The barrier function of the intestinal epithelium is consequently distorted, and IBD develops. The mechanisms of these processes are still unclear and require further research.

Effect of Antioxidants on the Production of MCP-1 Chemokine by EA.hy926 Cells in Response to IL-6.

An elevated level of circulatory interleukin 6 (IL-6) is a biomarker for cytokine storm of various etiologies, including COVID-19, and contributes to poor prognosis. Vascular endothelial cells are one of the main targets of pathological action of IL-6. IL-6 activates the trans-signaling pathway via the formation of the IL-6/sIL-6Ra/gp130 receptor complex and subsequent activation of the JAK/STAT3 signaling pathway and PI3K/AKT and MEK/ERK kinases in some cases. Previously, it was shown by the authors' group and other researchers that reactive oxygen species (ROS), including mitochondrial ROS (mito-ROS), contribute to the induction of IL-6 expression in the endothelium, mainly due to increased activation of the transcription factor NF-kB. We have also shown that the mitochondria-targeted antioxidant SkQ1 (Plastoquinolyl-10(6'-decyltriphenyl)phosphonium) prevented tumor necrosis factor (TNF)-induced cytokine storm and death in mice. In the aortas of these animals, SkQ1 also prevented the increase in the expression of NF-kB-dependent genes, including the cytokine IL-6 and the chemokine MCP-1. In the current work, the hypothesis of mito-ROS involvement in the IL-6-signaling-mediated proinflammatory gene expression in endothelial cells is tested. SkQ1 suppressed the expression and secretion of the MCP-1 chemokine, induced by IL-6 in combination with sIL-6-Ra, but not the expression of ICAM-1 adhesion molecules in EA.hy926 human endothelial cells. Using specific inhibitors, the authors have shown that, in EA.hy926 cells, IL-6-induced expression of MCP-1 and ICAM-1 depends on the signaling protein and transcription activator STAT3 and, in some cases, on JNK, PI3K, and MEK1/2 kinases and is independent of p38 kinase. In this model, IL-6 induced rapid STAT3 activation, while ERK1/2 activation was less pronounced, and there was no IL-6 effect on Akt and JNK activation. SkQ1 partially suppressed STAT3 and ERK1/2 activation. Thus, we have shown that SkQ1 suppresses not only NF-kB-dependent expression of IL-6 and other proinflammatory genes but also IL-6-induced activation of JAK/STAT3 and STAT3-dependent expression of MCP-1, which probably contributes to the overall therapeutic effect of SkQ1.

Comparison of the Effects of Mitochondria-Targeted Antioxidant 10-(6'-Plastoquinonyl)Decyltriphenylphosphonium Bromide (SkQ1) and a Fragment of its Molecule Dodecyltriphenylphosphonium on Carrageenan-Induced Acute Inflammation in Mouse Model of Subcuteneous Air Pouch.

The effect of mitochondria-targeted antioxidant 10-(6'-plastoquinonyl) decyltriphenylphosphonium bromide (SkQ1) and its fragment dodecyltriphenylphosphonium (C12TPP), weak uncouplers of respiration and oxidative phosphorylation, was studied using a mouse model of carrageenan-induced acute inflammation in the subcutaneous air pouch. In our model, SkQ1 demonstrated a strong anti-inflammatory effect that manifested in a decrease in the absolute number of inflammatory cells, mainly neutrophils, and their relative number in parallel with an increase in macrophages and mast cell content in the inflammatory exudate. The concentration of proinflammatory cytokine IL-6 in the exudate also tended to decrease. C12TPP produced no significant effect on the inflammation process.

Mitochondria-Targeted Antioxidant SkQ1 (10-(6´-Plastoquinonyl)decyltriphenylphosphonium Bromide) Inhibits Mast Cell Degranulation in vivo and in vitro.

The therapeutic effect of mitochondria-targeted antioxidant 10-(6´-plastoquinonyl)decyltriphenylphosphonium bromide (SkQ1) in experimental models of acute inflammation and wound repair has been shown earlier. It was suggested that the antiinflammatory activity of SkQ1 is related to its ability to suppress inflammatory activation of the vascular endothelium and neutrophil migration into tissues. Here, we demonstrated that SkQ1 inhibits activation of mast cells (MCs) followed by their degranulation and histamine release in vivo and in vitro. Intraperitoneal injections of SkQ1 in the mouse air-pouch model reduced the number of leukocytes in the air-pouch cavity and significantly decreased the histamine content in it, as well as suppressing MC degranulation in the air-pouch tissue. The direct effect of SkQ1 on MCs was studied in vitro in the rat basophilic leukemia RBL-2H3 cell line. SkQ1 inhibited induced degranulation of RBL-2H3 cells. These results suggest that mitochondrial reactive oxygen species are involved in the activation of MCs. It is known that MCs play a crucial role in regulation of vascular permeability by secreting histamine. Suppression of MC degranulation by SkQ1 might be a significant factor in the antiinflammatory activity of this mitochondria-targeted antioxidant.

[Surgical Site Infections after Open Appendectomy and Effectiveness of Complex Approach to Their Prevention].

AIM: To assess an incidence rate of surgical site infections (SSI) after open appendectomy and effectiveness of combined preventive measures (CPM). MATERIAL AND METHODS: This study was performed at three surgical departments of Smolensk hospitals. A total of 150 consecutive patients (50 at each department) hospitalized since January 2012 were included into the retrospective observation (period I). In order to perform prospective evaluation of CPM, a total of 66 consecutive patients (randomized 1:1) hospitalized since December 2012 (period II) were followed up at each of the departments. Antibiotic prophylaxis (AP) with IV amoxicillin/clavulanate (1.2 g) was planned for all patients from period II. The study group (group 1) included patients with surgical wound closure with triclosan-coated polyglactin 910 and additionally with a skin 2-octylcyanoacrylate-based adhesive. The control group (group 2) included patients with surgical wound closure with non-triclosan-coated polyglactin 910. Each patient from the period II was assigned to an "Individual SSI Prevention Package" (IPP), which included an antibiotic, sutures, skin adhesive (only in a package for CPM) and label "AP" for patients' medical records. Patients' medical records were reviewed by one expert. Exclusion criteria were: age <14 years; transition to midline laparotomy; drainage of the abdominal cavity through the surgical wound; simultaneous interventions; secondary appendicitis; refusal to use of sutures from the IPP. In order to determine signs of SSI presence/absence within 30 days after surgery, attempts to contact with patients by phone were made. The data obtained was recorded into case report forms and then entered into the study database. RESULTS: A total of 322 patients were included into the final analysis (mean age: 34.8±17.1 years). The mean length of hospital stay was 8.2±2.5 days. The mean duration of hospital stay with or without SSI was 7.9±1.8 and 14.2±4.0 days, respectively (p<0.001). The AP during the periods I and II was performed in 56.1% (83/148) and 97.7% (170/174) of patients, respectively (p<0.00001). Cephalosporins I-IV were the most frequently used antibiotics during the period I (85.6%). During the period II, amoxicillin/clavulanate from IPP was used in 98.2% of patients. Percentage of IV antibiotic administration in different time periods was 57.3% and 98.2%, respectively (p<0.0001); frequency of the first administration before skin incision was 53.6% and 97.1%, respectively (p<0.0001). The telephone contact with patient was successful in 74.8% (both periods), 56.8% (period I) and 90.2% (period II) of cases, respectively. SSI was recorded only once per patient with the following priority: SSI was documented in the patient's medical record; patient developed SSI that was not documented (in the expert's opinion) in the patient's medical record; SSI signs were determined during the telephone contact or reported by the patient. The incidence of SSI in both study periods, period I and period II was 14.9%, 15.5% and 14.4%, respectively (p>0.05 for all comparisons). In the patient subgroup with successful telephone contact, the incidence of SSI in both study periods, period I and period II was 17.4%, 21.4% and 15.3%, respectively; the incidence of SSI in group 1 and group 2 of the period II was 12.0% and 18.9%, respectively (p>0.05 for all comparisons). CONCLUSION: SSI after an open appendectomy remains an important problem. In order to determine a true incidence of SSI, it is necessary to improve the national nosocomial infection surveillance system. The CMP used in the study have showed a trend to significant SSI risk reduction and may be recommended to maximize patient protection. Further large studies are needed to confirm effectiveness of the proposed CMP.

Role of Reactive Oxygen Species in Mast Cell Degranulation.

Mast cells are a heterogeneous multifunctional cellular population that promotes connective tissue homeostasis by slow release of biologically active substances, affecting primarily the permeability of vessels and vascular tone, maintenance of electrolyte and water balance, and composition of the extracellular matrix. Along with this, they can rapidly release inflammatory mediators and chemotactic factors that ensure the mobilization of effector innate immune cells to fight against a variety of pathogens. Furthermore, they play a key role in initiation of allergic reactions. Aggregation of high affinity receptors to IgE (FcεRI) results in rapid degranulation and release of inflammatory mediators. It is known that reactive oxygen species (ROS) participate in intracellular signaling and, in particular, stimulate production of several proinflammatory cytokines that regulate the innate immune response. In this review, we focus on known molecular mechanisms of FcεRI-dependent activation of mast cells and discuss the role of ROS in the regulation of this pathway.

A cytofluorometric study of membrane rafts in human monocyte subsets in atherosclerosis.

The peripheral blood monocytes of atherosclerotic patients are pre-activated and have some of the features of tissue macrophages. Their adhesion to the endothelium is 1.5 times higher than that of monocytes from healthy subjects, and they express a number of receptors and antigens typical of tissue macrophages. Additionally, earlier we showed that the biosynthesis of gangliosides, whose main function is the formation of membrane rafts, is significantly activated in blood monocytes from atherosclerotic patients, as well as during the in vitro differentiation of normal monocytes into macrophages. In this study, we investigated the expression of membrane rafts on various monocyte subsets from healthy subjects and atherosclerotic patients. Based on flow cytometry results, the monocytes in the examined atherosclerotic patients were found to differ from those in healthy subjects by a twofold increase in the proportion of the intermediate subset (CD14(++)/CD16(+)) and by enhancement in the expression of the fractalkine receptor CX3CR1 on the intermediate and non-classical subsets (CD14(++)/CD16(+) and CD14(+)/CD16(++)) (2.3 and 1.8 times, respectively). This suggests a pre-activated state of monocytes in atherosclerotic patients. At the same time, the expression of the membrane raft marker on the monocyte subsets was similar in both studied groups. However, a study of the in vitro differentiation of monocytes into macrophages showed that the membrane raft expression increased 2 times as early as on the 1st day of culturing and 3 times on the 7th day compared to that in freshly isolated monocytes. Therefore, it is suggested that monocytes in atherosclerosis accumulate gangliosides that are used to form membrane rafts during the macrophage differentiation after the migration of monocytes into the arterial intima.