Systematic review and meta-analysis of dysregulated microRNAs derived from liquid biopsies as biomarkers for amyotrophic lateral sclerosis

The discovery of disease-specific biomarkers, such as microRNAs (miRNAs), holds the potential to transform the landscape of Amyotrophic Lateral Sclerosis (ALS) by facilitating timely diagnosis, monitoring treatment response, and accelerating drug discovery. Such advancement could ultimately improve the quality of life and survival rates for ALS patients. Despite more than a decade of research, no miRNA biomarker candidate has been translated into clinical practice. We conducted a systematic review and meta-analysis to quantitatively synthesize data from original studies that analyzed miRNA expression from liquid biopsies via PCR and compared them to healthy controls. Our analysis encompasses 807 miRNA observations from 31 studies, stratified according to their source tissue. We identified consistently dysregulated miRNAs in serum (hsa-miR-3665, -4530, -4745-5p, -206); blood (hsa-miR-338-3p, -183-5p); cerebrospinal fluid (hsa-miR-34a-3p); plasma (hsa-miR-206); and neural-enriched extracellular vesicles from plasma (hsa-miR-146a-5p, -151a-5p, -10b-5p, -29b-3p, and -4454). The meta-analyses provided further support for the upregulation of hsa-miR-206, hsa-miR-338-3p, hsa-miR-146a-5p and hsa-miR-151a-5p, and downregulation of hsa-miR-183-5p, hsa-miR-10b-5p, hsa-miR-29b-3p, and hsa-miR-4454 as consistent indicators of ALS across independent studies. Our findings provide valuable insights into the current understanding of miRNAs' dysregulated expression in ALS patients and on the researchers' choices of methodology. This work contributes to the ongoing efforts towards discovering disease-specific biomarkers.

Pathophysiology of chikungunya virus infection associated with fatal outcomes

Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that causes acute, subacute, and chronic human arthritogenic diseases and, in rare instances, can lead to neurological complications and death. Here, we combined epidemiological, virological, histopathological, cytokine, molecular dynamics, metabolomic, proteomic, and genomic analyses to investigate viral and host factors that contribute to chikungunya-associated (CHIK) death. Our results indicate that CHIK deaths are associated with multi-organ infection, central nervous system damage, and elevated serum levels of pro-inflammatory cytokines and chemokines compared with survivors. The histopathologic, metabolite, and proteomic signatures of CHIK deaths reveal hemodynamic disorders and dysregulated immune responses. The CHIKV East-Central-South-African lineage infecting our study population causes both fatal and survival cases. Additionally, CHIKV infection impairs the integrity of the blood-brain barrier, as evidenced by an increase in permeability and altered tight junction protein expression. Overall, our findings improve the understanding of CHIK pathophysiology and the causes of fatal infections.

SARS-CoV-2 uses CD4 to infect T helper lymphocytes

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the agent of a major global outbreak of respiratory tract disease known as Coronavirus Disease 2019 (COVID-19). SARS-CoV-2 infects mainly lungs and may cause several immune-related complications, such as lymphocytopenia and cytokine storm, which are associated with the severity of the disease and predict mortality. The mechanism by which SARS-CoV-2 infection may result in immune system dysfunction is still not fully understood. Here, we show that SARS-CoV-2 infects human CD4⁺ T helper cells, but not CD8⁺ T cells, and is present in blood and bronchoalveolar lavage T helper cells of severe COVID-19 patients. We demonstrated that SARS-CoV-2 spike glycoprotein (S) directly binds to the CD4 molecule, which in turn mediates the entry of SARS- CoV-2 in T helper cells. This leads to impaired CD4 T cell function and may cause cell death. SARS-CoV-2-infected T helper cells express higher levels of IL-10, which is associated with viral persistence and disease severity. Thus, CD4-mediated SARS-CoV-2 infection of T helper cells may contribute to a poor immune response in COVID-19 patients.

COVID-19-related hyperglycemia is associated with infection of hepatocytes and stimulation of gluconeogenesis

Occurrence of hyperglycemia upon infection is associated with worse clinical outcome in COVID-19 patients. However, it is still unknown whether SARS-CoV-2 directly triggers hyperglycemia. Herein, we interrogated whether and how SARS-CoV-2 causes hyperglycemia by infecting hepatocytes and increasing glucose production. We performed a retrospective cohort study including patients that were admitted at a hospital with suspicion of COVID-19. Clinical and laboratory data were collected from the chart records and daily blood glucose values were analyzed to test the hypothesis on whether COVID-19 was independently associated with hyperglycemia. Blood glucose was collected from a subgroup of nondiabetic patients to assess pancreatic hormones. Postmortem liver biopsies were collected to assess the presence of SARS-CoV-2 and its transporters in hepatocytes. In human hepatocytes, we studied the mechanistic bases of SARS-CoV-2 entrance and its gluconeogenic effect. SARS-CoV-2 infection was independently associated with hyperglycemia, regardless of diabetic history and beta cell function. We detected replicating viruses in human hepatocytes from postmortem liver biopsies and in primary hepatocytes. We found that SARS-CoV-2 variants infected human hepatocytes in vitro with different susceptibility. SARS-CoV-2 infection in hepatocytes yields the release of new infectious viral particles, though not causing cell damage. We showed that infected hepatocytes increase glucose production and this is associated with induction of PEPCK activity. Furthermore, our results demonstrate that SARS-CoV-2 entry in hepatocytes occurs partially through ACE2- and GRP78-dependent mechanisms. SARS-CoV-2 infects and replicates in hepatocytes and exerts a PEPCK-dependent gluconeogenic effect in these cells that potentially is a key cause of hyperglycemia in infected patients.

First evaluation of the anxiolytic-like effects of a bromazepam‑palladium complex in mice

A significant fraction of patients are affected by persistent fear and anxiety. Currently, there are several anxiolytic drug options, however their clinical outcomes do not fully manage the symptoms. Here, we evaluated the effects of a bromazepam‑palladium derivative [2-{(7-bromo-2-oxo-1,3-dihydro-2H-1,4-benzodiazepin-5-il)pyridinyl-κ²-N,N}chloropalladium(II)], [(BMZ)PdCl₂], on fear/anxiety and memory-related behavior in mice. For this, female Swiss mice were treated intraperitoneally (i.p.) with saline (NaCl 0.9%) or [(BMZ)PdCl₂] (0.5, 5.0, or 50 μg/kg). After 30 min, different tests were performed to evaluate anxiety, locomotion, and memory. We also evaluated the acute toxicity of [(BMZ)PdCl₂] using a cell viability assay (neutral red uptake assay), and whether the drugs mechanism of action involves the γ-aminobutyric acid type A (GABA_A) receptor complex by pre-treating animals with flumazenil (1.0 mg/kg, i.p., a competitive antagonist of GABA_A-binding site). Our results demonstrate that [(BMZ)PdCl₂] induces an anxiolytic-like phenotype in the elevated plus-maze test and that this effect can be blocked by flumazenil. Furthermore, there were no behavioral alterations induced by [(BMZ)PdCl₂], as evaluated in the light-dark box, open field, and step-down passive avoidance tests. In the acute toxicity assay, [(BMZ)PdCl₂] presented IC₅₀ and LD₅₀ values of 218 ± 60 μg/mL and 780 ± 80 mg/kg, respectively, and GSH category 4. Taken together, our results show that the anxiolytic-like effect of acute treatment with [(BMZ)PdCl₂] occurs through the modulation of the benzodiazepine site in the GABA_A receptor complex. Moreover, we show indications that [(BMZ)PdCl₂] does not promote sedation and amnesia and presents the same toxicity as the bromazepam prototype.

Impact of Microbiota Depletion by Antibiotics on SARS-CoV-2 Infection of K18-hACE2 Mice

Clinical and experimental data indicate that severe acute respiratory syndrome coronavirus (SARS-CoV)-2 infection is associated with significant changes in the composition and function of intestinal microbiota. However, the relevance of these effects for SARS-CoV-2 pathophysiology is unknown. In this study, we analyzed the impact of microbiota depletion after antibiotic treatment on the clinical and immunological responses of K18-hACE2 mice to SARS-CoV-2 infection. Mice were treated with a combination of antibiotics (kanamycin, gentamicin, metronidazole, vancomycin, and colistin, Abx) for 3 days, and 24 h later, they were infected with SARS-CoV-2 B lineage. Here, we show that more than 80% of mice succumbed to infection by day 11 post-infection. Treatment with Abx had no impact on mortality. However, Abx-treated mice presented better clinical symptoms, with similar weight loss between infected-treated and non-treated groups. We observed no differences in lung and colon histopathological scores or lung, colon, heart, brain and kidney viral load between groups on day 5 of infection. Despite some minor differences in the expression of antiviral and inflammatory markers in the lungs and colon, no robust change was observed in Abx-treated mice. Together, these findings indicate that microbiota depletion has no impact on SARS-CoV-2 infection in mice.

Abnormal brown adipose tissue mitochondrial structure and function in IL10 deficiency

Background

Inflammation is the most relevant mechanism linking obesity with insulin-resistance and metabolic disease. It impacts the structure and function of tissues and organs involved in metabolism, such as the liver, pancreatic islets and the hypothalamus. Brown adipose tissue has emerged as an important component of whole body energy homeostasis, controlling caloric expenditure through the regulation of non-shivering thermogenesis. However, little is known about the impact of systemic inflammation on the structure and function of brown adipose tissue.

Methods

The relations between IL10 and mitochondria structure/function and also with thermogenesis were evaluated by bioinformatics using human and rodent data. Real-time PCR, immunoblot, fluorescence and transmission electron microscopy were employed to determine the effect of IL10 in the brown adipose tissue of wild type and IL10 knockout mice.

Findings

IL10 knockout mice, a model of systemic inflammation, present severe structural abnormalities of brown adipose tissue mitochondria, which are round-shaped with loss of cristae structure and increased fragmentation. IL10 deficiency leads to newborn cold intolerance and impaired UCP1-dependent brown adipose tissue mitochondrial respiration. The reduction of systemic inflammation with an anti-TNFα monoclonal antibody partially rescued the structural but not the functional abnormalities of brown adipose tissue mitochondria. Using bioinformatics analyses we show that in both humans and mice, IL10 transcripts correlate with mitochondrial lipid metabolism and caspase gene expression.

Interpretation

IL10 and systemic inflammation play a central role in the regulation of brown adipose tissue by controlling mitochondrial structure and function.

Fund

Sao Paulo Research Foundation grant 2013/07607-8.

Hypothalamic mitochondrial abnormalities occur downstream of inflammation in diet-induced obesity

Hypothalamic dysfunction is a common feature of experimental obesity. Studies have identified at least three mechanisms involved in the development of hypothalamic neuronal defects in diet-induced obesity: i, inflammation; ii, endoplasmic reticulum stress; and iii, mitochondrial abnormalities. However, which of these mechanisms is activated earliest in response to the consumption of large portions of dietary fats is currently unknown. Here, we used immunoblot, real-time PCR, mitochondrial respiration assays and transmission electron microscopy to evaluate markers of inflammation, endoplasmic reticulum stress and mitochondrial abnormalities in the hypothalamus of Swiss mice fed a high-fat diet for up to seven days. In the present study we show that the expression of the inflammatory chemokine fractalkine was the earliest event detected. Its hypothalamic expression increased as early as 3 h after the introduction of a high-fat diet and was followed by the increase of cytokines. GPR78, an endoplasmic reticulum chaperone, was increased 6 h after the introduction of a high-fat diet, however the actual triggering of endoplasmic reticulum stress was only detected three days later, when IRE-1α was increased. Mitofusin-2, a protein involved in mitochondrial fusion and tethering of mitochondria to the endoplasmic reticulum, underwent a transient reduction 24 h after the introduction of a high-fat diet and then increased after seven days. There were no changes in hypothalamic mitochondrial respiration during the experimental period, however there were reductions in mitochondria/endoplasmic reticulum contact sites, beginning three days after the introduction of a high-fat diet. The inhibition of TNF-α with infliximab resulted in the normalization of mitofusin-2 levels 24 h after the introduction of the diet. Thus, inflammation is the earliest mechanism activated in the hypothalamus after the introduction of a high-fat diet and may play a mechanistic role in the development of mitochondrial abnormalities in diet-induced obesity.