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The coronavirus disease 2019 (COVID‐19) pandemic is transmitted by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) and has affected millions of people all around the world, leading to more than 6.5 million deaths. The nucleocapsid (N) phosphoprotein plays important roles in modulating viral replication and transcription, virus‐infected cell cycle progression, apoptosis, and regulation of host innate immunity. As an immunodominant protein, N protein induces strong humoral and cellular immune responses in COVID‐19 patients, making it a key marker for studying N‐specific B cell and T cell responses and the development of diagnostic serological assays and efficient vaccines. In this review, we focus on the structural and functional features and the kinetic and epitope mapping of B cell and T cell responses against SARS‐CoV‐2 N protein to extend our understanding on the development of sensitive and specific diagnostic immunological tests and effective vaccines. [ABSTRACT FROM AUTHOR]

Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is the causative agent of the coronavirus disease 2019 (COVID‐19) pandemic. This disease has currently affected more than 346 million people and resulted in more than 5.5 million deaths in many countries. Neutralising monoclonal antibodies (MAbs) against the SARS‐CoV‐2 virus could serve as prophylactic/therapeutic agents in COVID‐19 infection by providing passive protection against the virus in individuals. Until now, no Food and Drug Administration/European Medicines Agency‐approved neutralising MAb against SARS‐CoV‐2 virus exists in the market, though a number of MAbs have been authorised for emergency use. Therefore, there is an urgent need for development of efficient anti‐SARS‐CoV‐2 neutralising MAbs for use in the clinic. Moreover, neutralising anti‐SARS‐CoV‐2 MAbs could be used as beneficial tools for designing epitope‐based vaccines against the virus. Given that the target epitope of a MAb is a crucial feature influencing its neutralising potency, target epitopes of neutralising anti‐SARS‐CoV‐2 MAbs already reported in the literature and reactivity of these MAbs with SARS‐CoV‐2 variants are reviewed herein. [ABSTRACT FROM AUTHOR]

Given the emergence of SARS-CoV-2 virus as a life-threatening pandemic, identification of immunodominant epitopes of the viral structural proteins, particularly the nucleocapsid (NP) protein and receptor-binding domain (RBD) of spike protein, is important to determine targets for immunotherapy and diagnosis. In this study, epitope screening was performed using a panel of overlapping peptides spanning the entire sequences of the RBD and NP proteins of SARS-CoV-2 in the sera from 66 COVID-19 patients and 23 healthy subjects by enzyme-linked immunosorbent assay (ELISA). Our results showed that while reactivity of patients' sera with reduced recombinant RBD protein was significantly lower than the native form of RBD (P  < 0.001), no significant differences were observed for reactivity of patients' sera with reduced and non-reduced NP protein. Pepscan analysis revealed weak to moderate reactivity towards different RBD peptide pools, which was more focused on peptides encompassing amino acids (aa) 181–223 of RBD. NP peptides, however, displayed strong reactivity with a single peptide covering aa 151–170. These findings were confirmed by peptide depletion experiments using both ELISA and western blotting. Altogether, our data suggest involvement of mostly conformational disulfide bond-dependent immunodominant epitopes in RBD-specific antibody response, while the IgG response to NP is dominated by linear epitopes. Identification of dominant immunogenic epitopes in NP and RBD of SARS-CoV-2 could provide important information for the development of passive and active immunotherapy as well as diagnostic tools for the control of COVID-19 infection. [ABSTRACT FROM AUTHOR]

Cancer stem cells population are necessary for cancerous invasion. Previous studies have indicated anti-tumor properties of probiotic Lactobacillus reuteri. At the current study, the effect of heat-killed sonicated (HK-SON) fraction and defined molecular weight secreted fractions from L. reuteri cell-free supernatant (CFS) on invasion and apoptosis levels of HT29-ShE cells was investigated. HT29-ShE cells were treated with a range of defined molecular weight fractions derived from CFS and HK-SON. A group of the cells was treated with uninoculated sterile bacterial growth media (MRS) as the negative control for 24 h. Afterward, real-time PCR analysis was done for investigating the relative production level of MMP-9, TIMP-1, and COX-2 mRNA. Matrigel-coated insert plates were used to evaluate cell invasion. The pro-apoptotic effect of CFS and HK-SON was determined using flowcytometry, and the gelatinolytic role of MMP-9 was analyzed via gelatin zymography. HK-SON treatment and defined fractions of CFS significantly decreased the cell invasion versus the MRS group (p < 0.05). Moreover, expression level and activity of MMP-9 was considerably reduced after processing with 10–50 kD, 50–100 kD, and > 100 kD, and HK-SON fractions (p < 0.05). Furthermore, crude CFS, and > 100 kD fraction significantly up-regulated the production level of TIMP-1 (p < 0.05) and HK-SON and > 100 kD fractions significantly increased the apoptosis percentage of HT29-ShE cells. Our results indicate the anti-metastatic and anti-proliferative properties of CFS derived from L. reuteri. Findings suggest that a secretory macromolecule (s) such as a polysaccharide, nucleic acid, or protein might exert these inhibitory effects on colon cancer stem-like cells. In conclusion, our results indicated that cell-free supernatant components can be used as the anti-metastatic agent. However, this study must be performed in experimental and in vivo models for further results. [ABSTRACT FROM AUTHOR]

The transcription factor T‐cell factor 3 (TCF3), one component of the Wnt pathway, is known as a cell‐intrinsic inhibitor of many pluripotency genes in embryonic stem cells (ESCs) that influences the balance between pluripotency and differentiation. In this study, the effects of inhibition of TCF3 transcription factor on the stemness of mouse ESCs (mESCs) were investigated using the decoy oligodeoxynucleotides (ODNs) strategy. The TCF3 decoy and its scramble ODNs were designed and synthesized. The interaction specificity of the TCF3 decoy with the TCF3 transcription factor was evaluated by the electrophoretic mobility shift assay. Subcellular localization was carried out using fluorescence and confocal microscopy. Self‐renewal and pluripotency of mESCs were analyzed by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide (MTT), cell cycle and apoptosis, alkaline phosphatase (ALP), embryoid body (EB) formation, and real‐time assays. All experiments were performed in triplicate. The results showed that knockdown of TCF3 by decoy ODNs transfection in mESCs led to an increase in the cell proliferation, ALP enzyme activity, and master regulatory stemness genes and a decrease in the number and diameter of EBs. These results supported TCF3 as a potential target to maintain the pluripotency and self‐renewal capacity of mESCs. Knockdown of the TCF3 transcription factor using decoy ODNs can be a promising method to maintain the stemness of stem cells in regenerative medicine and cell therapy researches. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effects of M2000, a novel non-steroidal anti-inflammatory drug (NSAID) with immunosuppressive property and without gastro-nephrotoxicitic effects on matrix metalloproteinases (MMP)-2 and (MMP)-9 in phorbol myristate acetate (PMA)-differentiated THP-1 cells. Gene expression and activity of MMP-2 and MMP-9 are inhibited respectively by the tissue inhibitor of matrix metalloproteinase (TIMP)-2 and (TIMP)-1 and are induced by extracellular matrix metalloproteinase inducer (CD147/EMMPRIN). In this study, real-time quantitative reverse transcription polymerase chain reaction (RT-PCR) was used to determine gene expression of MMP-2, MMP-9, TIMP-1, and TIMP-2. Flow cytometry and zymography were applied to determine cellular surface expression of CD147 and activity of MMP-2 and MMP-9, respectively. Our results showed that treatment of THP-1 cells with high concentration (25 µg/mL) of M2000 significantly decreased the cellular surface expression of CD147 (p<0.05) and the gene expression of MMP-2, MMP-9 and TIMP-1 (p<0.05), and inhibited the gelatinolytic activity of MMP-2 and MMP-9 (p<0.05). According to our results, M2000 can reduce inflammation through inhibition of the cellular surface expression of CD147 and decrease the gene expression and gelatinolytic activity of MMP-2 and MMP-9 in PMA-differentiated THP-1 cells. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effects of M2000, a novel non-steroidal anti-inflammatory drug (NSAID) with immunosuppressive property and without gastronephrotoxicitic effects on matrix metalloproteinases (MMP)-2 and (MMP)-9 in phorbol myristate acetate (PMA)-differentiated THP-1 cells. Gene expression and activity of MMP-2 and MMP-9 are inhibited respectively by the tissue inhibitor of matrix metalloproteinase (TIMP)-2 and (TIMP)-1 and are induced by extracellular matrix metalloproteinase inducer (CD147/EMMPRIN). In this study, real-time quantitative reverse transcription polymerase chain reaction (RT-PCR) was used to determine gene expression of MMP-2, MMP-9, TIMP-1, and TIMP- 2. Flow cytometry and zymography were applied to determine cellular surface expression of CD147 and activity of MMP-2 and MMP-9, respectively. Our results showed that treatment of THP-1 cells with high concentration (25 μg/mL) of M2000 significantly decreased the cellular surface expression of CD147 (p<0.05) and the gene expression of MMP-2, MMP-9 and TIMP-1 (p<0.05), and inhibited the gelatinolytic activity of MMP-2 and MMP-9 (p<0.05). According to our results, M2000 can reduce inflammation through inhibition of the cellular surface expression of CD147 and decrease the gene expression and gelatinolytic activity of MMP-2 and MMP-9 in PMA-differentiated THP-1 cells. [ABSTRACT FROM AUTHOR]