Effect of SARS-CoV-2 and Toxoplasma gondii co-infection on IFN-γ and TNF-α expression and its impact on disease severity.

The symptomatology of COVID-19 is dependent on the immune status and the cytokine response of the host. The cytokine level of the host is influenced by the presence of chronic persistent or latent infections with co-pathogens. Parasitic diseases are known to induce host immune-modulation which may impact the response to co-infection. Toxoplasmosis is a widespread protozoal infection that remains quiescent in its latent form to be re-activated during states of immune depression. Clinical data on the relation between toxoplasmosis and COVID-19 cytokine profile and symptomatology are still insufficient. Seventy-nine subjects were included in this study. Patients were diagnosed with COVID-19 by PCR. Serological testing for toxoplasmosis was performed by the detection of anti-Toxoplasma IgG antibodies, in addition to IgG avidity testing. IFN-γ and TNF-α levels were determined by RT-PCR. Among patients diagnosed with COVID-19, 67.1% were seronegative for anti-Toxoplasma IgG, while 32.9% were seropositive. High avidity was found in 10 cases (40% of seropositive cases), 4 of whom required ICU administration, while low avidity was found in 15 cases (60%), 7 of which were administered to the ICU. TNF-α and INF-γ levels were significantly higher in COVID-19 patients than in healthy control subjects. No significant association was found between the seroprevalence of toxoplasmosis and the presence of COVID-19 and its severity. Cytokines were significantly higher in both seropositive and seronegative COVID-19 patients than in their control counterparts. The high prevalence of toxoplasmosis merits further exploration of its relation to COVID-19 by mass studies.

Regulatory Role of circRNA-0067835 in Behcet Disease through Targeting Micro RNA-155: Implication of ATG1, AKT and MTOR.

Background: Autophagy has been proven to contribute to maintaining eukaryotic cells' normal intracellular homeostasis, whereas autophagy malfunction may predispose to Behcet Disease (BD). The accumulation of the products of autophagic degradation as well as impairment in autophagic flux in cases with BD, may be attributed to dysregulated miRNA-155 expression. This study attempts to determine the contribution of circRNA-0067835 in miRNA-155-mediated modulation of the autophagy axis as well as to investigate its impact on the production of pro-inflammatory cytokines in BD. Methods: This study was carried out on 40 cases with BD and 40 healthy control subjects. The collection of serum samples was done before performing a real-time PCR to estimate the relative gene expression of ATG1, AKT, miRNA-155, mTOR, TAB2, and circRNA-0067835. Additionally, IL-1ß, IL-17, and TNF-α serum levels were determined by ELISA. Results: Behcet Disease (BD) patients had significantly upregulated circRNA-0067835, with subsequent downregulation of its target gene, miRNA-155 than controls (P<0.05). In addition, decreased miRNA-155 gene expression was correlated with significantly increased TAB2 gene expression levels in BD patients compared to the controls (P<0.05). Furthermore, enhanced production of pro-inflammatory cytokines was detected in cases with BD than in controls. Conclusion: The correlation between circRNA-0067835 and miRNA-155 fairly contributes to the regulation of cytokine production in BD via the modulation of autophagy. The investigation of the circRNA-0067835 and the microRNA-155 and their downstream adaptor molecules could be a potential therapeutic agent for BD.

Potential Role of circRNA-HIPK3/microRNA-124a Crosstalk in the Pathogenesis of Rheumatoid Arthritis.

Background: Circular RNA-HIPK3 (CircHIPK3) has been shown to be aberrantly expressed in a variety of diseases, contributing to disease initiation and progression. The aim of the present study is to investigate the role of the circHIPK3 RNA/microRNA-124a interaction in the pathogenesis of rheumatoid arthritis (RA). Methods: This study included 79 RA patients and 30 control individuals. The patients involved were classified according to the disease activity score (DAS28) into mild (24 patients), moderate (24 patients), and severe (31 patients). Serum samples were collected to estimate the relative gene expression of circHIPK3 RNA and its target gene microRNA-124a by quantitative real time-PCR. Moreover, ELISA was used to detect the serum levels of monocyte chemoattractant protein-1 (MCP-1). Routine laboratory estimation of erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and rheumatoid factor (RF) was also done. Results: In all grades of RA groups, there was a significantly substantial elevation of circHIPK3 RNA gene expression, with subsequent downregulation of miRNA-124a when compared to the control group. CircHIPK3 and microRNA-124a expression have been established to be inversely linked. Also, estimation of serum levels of MCP-1, ESR, CRP, and RF exhibited a significant increase in all grades of RA as compared to the control group. Conclusion: CircHIPK3 and microRNA-124a might be regarded as key players in the pathogenesis of RA. The cross-talk between them appears to be responsible for inducing joint inflammation by increasing MCP-1 production. Targeting circHIPK3 and microRNA-124a, and their downstream adaptor molecules, poses a new challenge for RA therapy.

Active form of vitamin D analogue mitigates neurodegenerative changes in Alzheimer's disease in rats by targeting Keap1/Nrf2 and MAPK-38p/ERK signaling pathways.

BACKGROUND: The nuclear factor erythroid2-related factor2 (Nrf2), a chief transcriptional regulator of antioxidant response element (ARE), is considered a promising target for the prevention of Alzheimer's disease (AD). Vitamin D has been recognized to have a crucial role in improving AD cognitive functions. The present study was conducted to evaluate the effects of active vitamin D analogue, Maxacalcitol, on Keap1-Nrf2 signaling pathway in experimental Alzheimer's disease in rats. MATERIALS AND METHODS: The study was conducted on thirty female white albino rats divided equally into 3 groups: control group, Alzheimer group induced by Lipopolysaccharide and Alzheimer group treated with active vitamin D3 analogue, Maxacalcitol. The following parameters were assessed in rat brain tissues: Gene expression of Nrf2, Keap1 and MAF by RT-PCR, protein levels of phosphorylated MAPK-38p and ERK1/2 by Western Blot Technique, estimation of HO-1, Amyloid ß, p-Tau levels and serum levels of TNFα, IL-10 and total 25-hydroxyvitamin D, serum calcium levels, GSH and MDA levels were also estimated in addition to cognitive function tests and histo-pathological examination of rat brain tissues. RESULTS: In Alzheimer group, there was a significant deficit in cognition along with down-regulation of gene expression of Nrf2 and the protein levels of its downstream antioxidant effectors (HO-1 and GSH) with increased levels of the lipid peroxidation biomarker MDA. Also, there was increased neuro-inflammation as evidenced by increased levels of TNFα and decreased levels of IL-10. Moreover, there were increased amyloid ß load and enhanced levels of phosphorylation of MAPK-38 and ERK1/2 leading to hyperphosphorylation of Tau protein. In addition, there were decreased serum levels of both total 25-hydroxyvitamin D and calcium. Treatment with vitamin D3 analogue, Maxacalcitol significantly improved cognitive dysfunction and histopathological picture of the brains of Alzheimer rats. Also, Vitamin D analogue significantly increased expression of Nrf2 and its downstream effectors (HO-1 and GSH), improved serum levels of total 25-hydroxyvitamin D and calcium, decreased neuro-inflammation and Amyloid ß load as well as hyperphosphorylation of MAPK-38, ERK1/2 and tau proteins were also observed. Therefore, these data suggest that vitamin D analogue, Maxacalcitol could be used as a therapeutic agent in treatment of Alzheimer disease.

Impact of Mesenchymal Stem Cells and Vitamin D on Transforming Growth Factor Beta Signaling Pathway in Hepatocellular Carcinoma in Rats

Background: Transforming growth factor-beta (TGF-ß) signaling is recognized as being critical for carcinogenesis. Vitamin D has proved to exert numerous tumor suppressive effects. Effects of bone marrow derived mesenchymal stem cells (BM-MSCs) on tumor progression are still controversial. The present study was conducted to evaluate the effects of BM-MSCs and vitamin D on TGF-ß signaling in an experimental hepatocellular carcinoma (HCC) model in rats. Materials and Methods: The study was conducted on fifty female white albino rats divided equally into 5 groups: controls, HCC induced by diethyl-nitrosamine (DENA) and carbon tetrachloride (CCl4), HCC plus MSCs, HCC plus vitamin D and HCC plus both MSCs and vitamin D. The following parameters were assessed in rat liver tissues: TGF-ß and Smad2 protein levels by ELISA and western blotting, respectively, gene expression of Smad3, Smad7, Snail, HNF4α and MMP-2 and histopathological lesions. Serum levels of alpha fetoprotein (AFP), ALT and albumin were also assessed. Results: TGF-ß protein levels and gene expression of its downstream effectors (Smad3 and Snail), in addition to Smad2 protein levels were significantly higher in the HCC group than in the control group. On the other hand, they were significantly down-regulated in all treated groups with most significant amelioration with both MSCs and vitamin D. Also, the serum levels of AFP were significantly increased in the untreated HCC group, and this was again reversed in all treated groups. Histopathological examination of liver tissue revealed that administration of MSCs or vitamin D into HCC rat group improved the histopathological picture with residual tumor pathology, while administration of both MSCs and vitamin D showed better restoration of liver parenchyma. These data suggest that the TGF-ß signaling pathway could be used as a therapeutic target in HCC.