COVID-19 Complications: Oxidative Stress, Inflammation, and Mitochondrial and Endothelial Dysfunction.

SARS-CoV-2 infection, discovered and isolated in Wuhan City, Hubei Province, China, causes acute atypical respiratory symptoms and has led to profound changes in our lives. COVID-19 is characterized by a wide range of complications, which include pulmonary embolism, thromboembolism and arterial clot formation, arrhythmias, cardiomyopathy, multiorgan failure, and more. The disease has caused a worldwide pandemic, and despite various measures such as social distancing, various preventive strategies, and therapeutic approaches, and the creation of vaccines, the novel coronavirus infection (COVID-19) still hides many mysteries for the scientific community. Oxidative stress has been suggested to play an essential role in the pathogenesis of COVID-19, and determining free radical levels in patients with coronavirus infection may provide an insight into disease severity. The generation of abnormal levels of oxidants under a COVID-19-induced cytokine storm causes the irreversible oxidation of a wide range of macromolecules and subsequent damage to cells, tissues, and organs. Clinical studies have shown that oxidative stress initiates endothelial damage, which increases the risk of complications in COVID-19 and post-COVID-19 or long-COVID-19 cases. This review describes the role of oxidative stress and free radicals in the mediation of COVID-19-induced mitochondrial and endothelial dysfunction.

Direct Application of 3-Maleimido-PROXYL for Proving Hypoalbuminemia in Cases of SARS-CoV-2 Infection: The Potential Diagnostic Method of Determining Albumin Instability and Oxidized Protein Level in Severe COVID-19.

Oxidative stress and the albumin oxidized form can lead to hypoalbuminemia, which is a predisposing factor for reduced treatment effectiveness and an increased mortality rate in severe COVID-19 patients. The aim of the study is to evaluate the application of free radical 3-Maleimido-PROXYL and SDSL-EPR spectroscopy in the in vitro determination of ox/red HSA in serum samples from patients with SARS-CoV-2 infection. Venous blood was collected from patients intubated (pO2 < 90%) with a positive PCR test for SARS-CoV-2 and controls. At the 120th minute after the incubation of the serum samples from both groups with the 3-Maleimido-PROXYL, the EPR measurement was started. The high levels of free radicals were determined through the nitroxide radical TEMPOL, which probably led to increased oxidation of HSA and hypoalbuminemia in severe COVID-19. The double-integrated spectra of 3-Maleimido-PROXYL radical showed a low degree of connectivity due to high levels of oxidized albumin in COVID-19 patients. The low concentrations of reduced albumin in serum samples partially inhibit spin-label rotation, with Amax values and ΔH0 spectral parameters comparable to those of 3-Maleimido-PROXYL/DMSO. Based on the obtained results, we suggest that the stable nitroxide radical 3-Maleimido-PROXYL can be successfully used as a marker to study oxidized albumin levels in COVID-19.

Site-Directed Spin Labeling EPR Spectroscopy for Determination of Albumin Structural Damage and Hypoalbuminemia in Critical COVID-19.

The main factors in the COVID-19 pathology, which can initiate extensive structural changes at the cellular and molecular levels, are the generation of free radicals in abnormal amounts, and oxidative stress. Under "oxidative shock" conditions, the proteins undergo various modifications that affect their function and activity, and as a result distribute malfunctioning protein derivatives in the body. Human serum albumin is a small globular protein characterized by a high overall binding capacity for neutral lipophilic and acidic dosage forms. The albumin concentration is crucial for the maintenance of plasma oncotic pressure, the transport of nutrients, amino acids, and drugs, the effectiveness of drug therapy, and the prevention of drug toxicity. Hypoalbuminemia and structural defects molecule in the protein suggest a risk of changed metabolism and increased plasma concentration of unbound drugs. Therefore, the albumin structural and functional changes accompanied by low protein levels can be a serious prerequisite for ineffective therapy, frequent complications, and high mortality in patients with SARS-CoV-2 infection. The current opinion aims the research community the application of Site-Directed Spin Labeling Electron Paramagnetic Resonance spectroscopy (SDSL-EPR) and 3-Maleimido-PROXYL radical in determining abnormalities of the albumin dynamics and protein concentrations in COVID-19 critical patients.

Investigation of the role of MMP3 -1171insA polymorphism in cutaneous malignant melanoma - a preliminary study.

Coetaneous malignant melanoma is the most aggressive cancer of the skin with a high rate of mortality worldwide. Degradation of basement membranes and extracellular matrix is an essential step in cancer invasion and metastasis. Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) play key roles in this step. MMP-3 also called stromelysin-1 was one of the first proteinases found to be associated with cancer. In the gene of MMP-3 (MMP3), an insertion/deletion of an A nucleotide at position -1171 in promoter region has been identified and shown to effect the expression activity of the gene. The present study was conducted to investigate the relation of MMP3 -1171insA polymorphism with skin malignant melanoma risk in a pilot case-control study of Bulgarian patients (n = 26) and unaffected controls (n = 172). The genotypes of controls and melanoma patients were in Hardy-Weinberg equilibrium. The results showed no statistically significant difference both in genotype and allele frequencies of MMP3 -1171insA polymorphism between melanoma patients and healthy controls either in crude analyses (p = 0.360 and 0.790, c2-test) or after adjustment for age and sex. The comparison of some clinical characteristics between the patients with different genotypes showed a trend for longer survival of patients with 6A/6A genotype compared to the carriers of 5A allele (5A/5A+5A/6A genotypes, p = 0.118, Log rank test). The results of our current preliminary study do not provide evidence for the role of the promoter polymorphism -1171insA in MMP3 as a risk factor for development of coetaneous melanoma, but suggest its implication in progression of the diseases.

Role of dendritic cells in progression and clinical outcome of colon cancer.

PURPOSE: The dendritic cells (DCs) are key players in the initiation and regulation of immune responses including antitumor immunity. In the current study, we aimed to elucidate the role of different subtypes of DCs infiltrating the tumor stroma and invasive margin for tumor progression and survival of patients with colon cancer. METHODS: The presence of immature (CD1a- and S100 protein+) and mature (CD83- and HLA-DR+) DCs was evaluated by immunohistochemistry in tissue samples from 145 patients with colon cancer. Patients were dichotomized according to the number of DCs in the tumor stroma and invasive margin, and clinical, histological, and survival data were compared between the two groups of patients. RESULTS: The number of the mature CD83+ DCs in the tumor stroma and in the invasive margin significantly correlated with the tumor stage: the lower level of infiltration was found in patients that have advanced tumor stage. The frequency of distant metastases was higher in patients who had lower numbers of immature CD1a+ DCs in tumor stroma and of CD83+ DCs in invasive margin. Patients showing a relatively high number of S100+ DCs in the tumor stroma and HLA-DR+ DCs in the invasive margin had a longer overall survival (p < 0.05). Patients with lower CD83+ DCs infiltration in invasive margin had worse prognosis after surgical therapy compared with those with higher CD83+ DCs infiltration (p = 0.0397). CONCLUSIONS: Our results demonstrate that the infiltration of colon cancer with DCs is related with tumor progression and patient prognosis, suggesting a central role for DCs in controlling local antitumor immunity.

Role of TGF-beta1, its receptor TGFbetaRII, and Smad proteins in the progression of colorectal cancer.

AIM: In the current study, we investigated the expression of TGF-beta1, its receptor TGFbetaRII, and the signaling proteins Smad4 and Smad7 in colorectal cancer tissue in relation to infiltration with antigen-presenting cells and some clinical and pathologic parameters of disease progression in patients with colorectal cancer (CRC). MATERIALS AND METHODS: The immunohistochemical expression of TGF-beta1, TGFbetaRII, Smad4, Smad7, HLA-DR antigen, CD1a, CD83, and CD68 was evaluated in 142 patients (50 females and 92 males) with CRC, followed-up for 6-8 years period. RESULTS: In our study, 127 (89.4%) out of 142 colorectal cancers displayed cytoplasmic TGF-beta1 immunoreactivity. Common-mediator Smad4 was detected in the tumor cytoplasm in 124 cancers (79.5%) and inhibitory Smad7 immunostaining was observed in 110 (77.4%) tumor specimens. TGFbetaRII was expressed on tumor cell membranes in 119 (76.3%) of the cancers. The increased TGF-beta1 expression in tumor cytoplasm was related to low CD68(+)- and CD83(+)-cell infiltration in tumor tissues. Patients with TGF-beta1 overexpression had worse prognosis after surgical therapy compared to those with low expression of TGF-beta1. The observed association was more pronounced for the patients in T1-T2 stage (p = 0.0015). CONCLUSIONS: The expression of TGF-beta1, its receptor TGFbetaRII, and signaling proteins Smad4 and Smad7 was observed in the majority of colorectal cancer specimens. Our results suggest that TGF-beta1 production by tumor cells may affect the tumor environment via suppression of tumor-infiltrating immune cells and probably contributes to tumor cells aggressiveness through autocrine activation of Smad signaling.

Application of light microscopical and ultrastructural immunohistochemistry in the study of goblet cell carcinoid in the appendix.

BACKGROUND: Goblet cell carcinoids appear less frequently in the appendix than do other carcinoids. In the presented work a case with a goblet cell carcinoid of the appendix is described. METHODS: Routine histological and histochemical methods were employed, with a combination of histochemistry and immunohistochemistry on one section and light and electron microscopical immunohistochemisty on paraffin-embedded material, were applied to identify the type of the carcinoid and to reveal the fine structure of cell types in the tumour nests of the appendix. RESULTS: During the biopsy of a patient who had undergone appendectomy, an infiltration with clusters of goblet cells in the submucosa of the appendix was found. After a second operation of right-sided hemicolectomy, similar clusters of goblet cells were detected in the muscle layers of the caecum. After 18 months the patient died from cirrhosis and had not developed metastases or any recurrence. Immunohistochemically the serotonin-, somatostatin-, chromogranin A- and synaptophysin-positive endocrine cells were basally attached to mucin-secreting cells. The combined staining revealed simultaneously present endocrine cells (chromogranin-A-positive) and mucin-secreting cells (PAS- or alcian blue-positive). The ultrastructural immunohistochemistry showed that chromogranin A-positive cells had discoid and pleomorphic granules and were located in tumour nests or as single cells in the appendiceal wall. CONCLUSION: The combined histochemical and immunohistochemical procedure and the ultrastructural immunohistochemistry on archival material could contribute in clarifying the diagnosis of goblet cell carcinoid.