Direct and indirect impact of SARS-CoV-2 on the brain.

Although COVID-19 is mostly a pulmonary disease, it is now well accepted that it can cause a much broader spectrum of signs and symptoms and affect many other organs and tissue. From mild anosmia to severe ischemic stroke, the impact of SARS-CoV-2 on the central nervous system is still a great challenge to scientists and health care practitioners. Besides the acute and severe neurological problems described, as encephalopathies, leptomeningitis, and stroke, after 2 years of pandemic, the chronic impact observed during long-COVID or the post-acute sequelae of COVID-19 (PASC) greatly intrigues scientists worldwide. Strikingly, even asymptomatic, and mild diseased patients may evolve with important neurological and psychiatric symptoms, as confusion, memory loss, cognitive decline, chronic fatigue, associated or not with anxiety and depression. Thus, the knowledge on the correlation between COVID-19 and the central nervous system is of great relevance. In this sense, here we discuss some important mechanisms obtained from in vitro and in vivo investigation regarding how SARS-CoV-2 impacts the brain and its cells and function.

Neuroinflammation at single cell level: What is new?

Multiple sclerosis is a chronic and demyelinating disease of the central nervous system (CNS), most prevalent in women, and with an important social and economic cost worldwide. It is triggered by self-reacting lymphocytes that infiltrate the CNS and initiate neuroinflammation. Further, axonal loss and neuronal death takes place, leading to neurodegeneration and brain atrophy. The murine model for studying MS, experimental autoimmune encephalomyelitis (EAE), consists in immunizing mice with myelin-derived epitopes. APCs activate encephalitogenic T CD4 and CD8 lymphocytes that migrate mainly to the spinal cord resulting in neuroinflammation. Most of the knowledge on the pathophysiology and treatment of MS was obtained from EAE experiments, as Th17 cells, anti-alpha4 blocking Abs and the role of microbiota. Conversely, recent technology breakthroughs, such as CyTOF and single-cell RNA-seq, promise to revolutionize our understanding on the mechanisms involved both in MS and EAE. In fact, the importance of specific cellular populations and key molecules in MS/EAE is a constant matter of debate. It is well accepted that both Th1 and Th17 T CD4 lymphocytes play a relevant role in disease initiation after re-activation in situ. What is still under constant investigation, however, is the plasticity of the lymphocyte population, and the individual contribution of both resident and inflammatory cells for the progression or recovery of the disease. Thus, in this review, new findings obtained after single-cell analysis of blood and central nervous system infiltrating cells from MS/EAE and how they have contributed to a better knowledge on the cellular and molecular mechanisms of neuroinflammation are discussed.

COVID-19 Pandemic and Dysbiosis: Can the Ivermectin Hysteria Lead to an Increase of Autoimmune Neuroinflammatory Diseases?

The pandemic caused by the SARS-CoV-2 has made new treatments a goal for the scientific community. One of these treatments is Ivermectin. Here we discuss the hypothesis of dysbiosis caused by the use of Ivermectin and the possible impacts on neuroinflammatory diseases after the end of the pandemic.

Endostatin gene therapy stimulates upregulation of ICAM-1 and VCAM-1 in a metastatic renal cell carcinoma model.

One of the greatest challenges in urological oncology is renal cell carcinoma (RCC), which is the third leading cause of death in genitourinary cancers. RCCs are highly vascularized and respond positively to antiangiogenic therapy. Endostatin (ES) is a fragment of collagen XVIII that possesses antiangiogenic activity. In this study, we examined the potential of ES-based antiangiogenic therapy to activate tumor-associated endothelial cells in metastatic RCC (mRCC). Balb/c-bearing Renca cells were treated with NIH/3T3-LendSN or, as a control, with NIH/3T3-LXSN cells. The T-cell subsets and lymphocyte populations of tumors, mediastinal lymph nodes and the spleen were assessed by flow cytometry. The expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) was assessed by real-time PCR, flow cytometry and immunohistochemistry analysis. ES gene therapy led to an increase in the percentage of infiltrating CD4-interferon (IFN)-γ cells (P<0.05), CD8-IFN-γ cells (P<0.01) and CD49b-tumor necrosis factor-α cells (P<0.01). In addition, ES therapy caused an increase at the mRNA level of ICAM-1 (1.4-fold; P<0.01) and VCAM-1 (1.5-fold) (control vs treated group; P<0.001). Through flow cytometry, we found a significant increase in the CD34/ICAM-1 cells (8.1-fold; P<0.001) and CD34/VCAM-1 cells (1.6-fold; P<0.05). ES gene therapy induced a significant increase in both T CD4 and CD8 cells in the lymph nodes and the spleen, suggesting that ES therapy may facilitate cell survival or clonal expansion. CD49b cells were also present in increased quantities in all of these organs. In this study, we demonstrate an antitumor inflammatory effect of ES in an mRCC model, and this effect is mediated by an increase in ICAM-1 and VCAM-1 expression in tumor-associated endothelial cells.

IL-10 and TGF-beta immunoregulatory cytokines rather than natural regulatory T cells are associated with the resolution phase of Vogt-Koyanagi-Harada (VKH) syndrome.

The pro-inflammatory cytokines play a critical role in the initiation and propagation of ocular autoimmune diseases. Regulation of these cytokines is generally mediated by the immunoregulatory cytokine such as IL-10 or TGF-beta. In this study, we investigated the immunoregulatory cytokine profile and frequency of natural regulatory T cells (nTregs) in patients with Vogt-Koyanagi-Harada (VKH). We obtained the peripheral blood mononuclear cells (PBMC) from patients with VKH and healthy controls. The cytokine profile from supernatants of PBMC cultured with or without phytohaemagglutinin (PHA) was measured by ELISA, the percentage of CD4(+) Foxp3(+) and CD25(high)Foxp3(+) T regulatory cells were analysed by flow cytometry, and the transcriptional level of Foxp3 expression was analysed by real-time quantitative PCR. The immunoregulatory cytokines, TGF-beta and IL-10, increased in patients with VKH in the inactive stage of the disease. We observed no significant difference in the CD4(+) Foxp3(+) and CD25(high)Foxp3(+) T cells as well as no reduction in FOXP3 mRNA expression in the patients with VKH when compared to healthy controls. We showed in our work, an increase in IFN-gamma secretion by PBMC of patients with VKH in the active stage of the disease when compared to healthy controls and patients in the inactive stage. Our data suggest that IL-10 and TGF-beta cytokines, rather than nTregs are associated with the resolution phase of the disease and may have a more relevant role in controlling this disease.

Protective immunity against Trypanosoma cruzi provided by oral immunization with Phytomonas serpens: role of nitric oxide.

We have previously demonstrated that Phytomonas serpens, a tomato parasite, shares antigens with Trypanosoma cruzi, the protozoa that causes Chagas' disease. These antigens are recognized by human sera and induce protective immunity in Balb/c mice. In the present study, inducible nitric oxide synthase (iNOS) knockout (KO) mice and C57BL/6 mice treated with the nitric oxide inhibitor, aminoguanidine (AG, 50 mg kg(-1)) infected with T. cruzi, were used to demonstrate the role of nitric oxide (NO) to host protection against T. cruzi infection achieved by oral immunization with live P. serpens. A reduction in parasitaemia and an increase in survival were observed in C57BL/6 infected mice and previously immunized with P. serpens, when compared to non-immunized mice. iNOS (KO) mice immunized and C57BL/6 immunized and treated with AG presented parasitaemia and mortality rates comparable to those of infected and non-immunized mice. By itself, immunization with P. serpens did not induce inflammation in the myocardium, but C57BL/6 mice so immunized showed fewer amastigotes nests in the heart following an acute T. cruzi infection than those in non-immunized mice. These results suggest that protective immunity against T. cruzi infection induced by immunization with P. serpens is dependent upon enhanced NO production during the acute phase of T. cruzi infection.