Angiotensin-(1-7) decreases inflammation and lung damage caused by betacoronavirus infection in mice.

OBJECTIVE: Pro-resolving molecules, including the peptide Angiotensin-(1-7) [Ang-(1-7)], have potential adjunctive therapy for infections. Here we evaluate the actions of Ang-(1-7) in betacoronavirus infection in mice. METHODS: C57BL/6J mice were infected intranasally with the murine betacoronavirus MHV-3 and K18-hACE2 mice were infected with SARS-CoV-2. Mice were treated with Ang-(1-7) (30 µg/mouse, i.p.) at 24-, 36-, and 48-hours post-infection (hpi) or at 24, 36, 48, 72, and 96 h. For lethality evaluation, one additional dose of Ang-(1-7) was given at 120 hpi. At 3- and 5-days post- infection (dpi) blood cells, inflammatory mediators, viral loads, and lung histopathology were evaluated. RESULTS: Ang-(1-7) rescued lymphopenia in MHV-infected mice, and decreased airways leukocyte infiltration and lung damage at 3- and 5-dpi. The levels of pro-inflammatory cytokines and virus titers in lung and plasma were decreased by Ang-(1-7) during MHV infection. Ang-(1-7) improved lung function and increased survival rates in MHV-infected mice. Notably, Ang-(1-7) treatment during SARS-CoV-2 infection restored blood lymphocytes to baseline, decreased weight loss, virus titters and levels of inflammatory cytokines, resulting in improvement of pulmonary damage, clinical scores and lethality rates. CONCLUSION: Ang-(1-7) protected mice from lung damage and death during betacoronavirus infections by modulating inflammation, hematological parameters and enhancing viral clearance.

SOCS2 regulates alveolar bone loss in Aggregatibacter actinomycetemcomitans-induced periodontal disease.

INTRODUCTION: The role of suppressor of cytokine signaling 2 (SOCS2) in Aggregatibacter actinomycetemcomitans (Aa)-induced alveolar bone loss is unknown; thus, it was investigated in this study. METHODS: Alveolar bone loss was induced by infecting C57BL/6 wild-type (WT) and Socs2-knockout (Socs2-/-) mice with Aa. Bone parameters, bone loss, bone cell counts, the expression of bone remodeling markers, and cytokine profile were evaluated by microtomography, histology, qPCR, and/or ELISA. Bone marrow cells (BMC) from WT and Socs2-/- mice were differentiated in osteoblasts or osteoclasts for analysis of the expression of specific markers. RESULTS: Socs2-/- mice intrinsically exhibited irregular phenotypes in the maxillary bone and an increased number of osteoclasts. Upon Aa infection, SOCS2 deficiency resulted in the increased alveolar bone loss, despite decreased proinflammatory cytokine production, in comparison to the WT mice. In vitro, SOCS2 deficiency resulted in the increased osteoclasts formation, decreased expression of bone remodeling markers, and proinflammatory cytokines after Aa-LPS stimulus. CONCLUSIONS: Collectively, data suggest that SOCS2 is a regulator of Aa-induced alveolar bone loss by controlling the differentiation and activity of bone cells, and proinflammatory cytokines availability in the periodontal microenvironment and an important target for new therapeutic strategies. Thus, it can be helpful in preventing alveolar bone loss in periodontal inflammatory conditions.

The glycosaminoglycan-binding chemokine fragment CXCL9(74-103) reduces inflammation and tissue damage in mouse models of coronavirus infection.

Introduction: Pulmonary diseases represent a significant burden to patients and the healthcare system and are one of the leading causes of mortality worldwide. Particularly, the COVID-19 pandemic has had a profound global impact, affecting public health, economies, and daily life. While the peak of the crisis has subsided, the global number of reported COVID-19 cases remains significantly high, according to medical agencies around the world. Furthermore, despite the success of vaccines in reducing the number of deaths caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), there remains a gap in the treatment of the disease, especially in addressing uncontrolled inflammation. The massive recruitment of leukocytes to lung tissue and alveoli is a hallmark factor in COVID-19, being essential for effectively responding to the pulmonary insult but also linked to inflammation and lung damage. In this context, mice models are a crucial tool, offering valuable insights into both the pathogenesis of the disease and potential therapeutic approaches. Methods: Here, we investigated the anti-inflammatory effect of the glycosaminoglycan (GAG)-binding chemokine fragment CXCL9(74-103), a molecule that potentially decreases neutrophil transmigration by competing with chemokines for GAG-binding sites, in two models of pneumonia caused by coronavirus infection. Results: In a murine model of betacoronavirus MHV-3 infection, the treatment with CXCL9(74-103) decreased the accumulation of total leukocytes, mainly neutrophils, to the alveolar space and improved several parameters of lung dysfunction 3 days after infection. Additionally, this treatment also reduced the lung damage. In the SARS-CoV-2 model in K18-hACE2-mice, CXCL9(74-103) significantly improved the clinical manifestations of the disease, reducing pulmonary damage and decreasing viral titers in the lungs. Discussion: These findings indicate that CXCL9(74-103) resulted in highly favorable outcomes in controlling pneumonia caused by coronavirus, as it effectively diminishes the clinical consequences of the infections and reduces both local and systemic inflammation.

Dietary Vitamin D Mitigates Coronavirus-Induced Lung Inflammation and Damage in Mice.

The COVID-19 pandemic caused by the SARS-CoV-2 (ß-CoV) betacoronavirus has posed a significant threat to global health. Despite the availability of vaccines, the virus continues to spread, and there is a need for alternative strategies to alleviate its impact. Vitamin D, a secosteroid hormone best known for its role in bone health, exhibits immunomodulatory effects in certain viral infections. Here, we have shown that bioactive vitamin D (calcitriol) limits in vitro replication of SARS-CoV-2 and murine coronaviruses MHV-3 and MHV-A59. Comparative studies involving wild-type mice intranasally infected with MHV-3, a model for studying ß-CoV respiratory infections, confirmed the protective effect of vitamin D in vivo. Accordingly, mice fed a standard diet rapidly succumbed to MHV-3 infection, whereas those on a vitamin D-rich diet (10,000 IU of Vitamin D3/kg) displayed increased resistance to acute respiratory damage and systemic complications. Consistent with these findings, the vitamin D-supplemented group exhibited lower viral titers in their lungs and reduced levels of TNF, IL-6, IL-1ß, and IFN-γ, alongside an enhanced type I interferon response. Altogether, our findings suggest vitamin D supplementation ameliorates ß-CoV-triggered respiratory illness and systemic complications in mice, likely via modulation of the host's immune response to the virus.

Purification and Biological Properties of Raniseptins-3 and -6, Two Antimicrobial Peptides from Boana raniceps (Cope, 1862) Skin Secretion.

The number of multidrug-resistant pathogenic microorganisms has been growing in recent years, most of which is due to the inappropriate use of the commercial antibiotics that are currently available. The dissemination of antimicrobial resistance represents a serious global public health problem. Thus, it is necessary to search for and develop new drugs that can act as antimicrobial agents. Antimicrobial peptides are a promising alternative for the development of new therapeutic drugs. Anurans' skin glands are a rich source of broad-spectrum antimicrobial compounds and hylids, a large and diverse family of tree frogs, are known as an important source of antimicrobial peptides. In the present study, two novel antimicrobial peptides, named Raniseptins-3 and -6, were isolated from Boana raniceps skin secretion and their structural and biological properties were evaluated. Raniseptins-3 and -6 are cationic, rich in hydrophobic residues, and adopt an α-helix conformation in the presence of SDS (35 mM). Both peptides are active against Gram-negative bacteria and Gram-positive pathogens, with low hemolytic activity at therapeutic concentrations. No activity was observed for yeasts, but the peptides are highly cytotoxic against B16F10 murine melanoma cells and NIH3T3 mouse fibroblast cells. None of the tested compounds showed improvement trends in the MTT and LDH parameters of MHV-3 infected cells at the concentrations tested.

Dysbiotic oral microbiota contributes to alveolar bone loss associated with obesity in mice.

INTRODUCTION: Periodontal diseases (PD) are inflammatory conditions that affect the teeth supporting tissues. Increased body fat tissues may contribute to activation of the systemic inflammatory response, leading to comorbidities. Some studies have shown that individuals with obesity present higher incidence of PD than eutrophics. OBJECTIVE: To investigate the impact of obesity on periodontal tissues and oral microbiota in mice. METHODOLOGY: Two obesity mice models were performed, one using 12 weeks of the dietary protocol with a high-fat (HF) diet in C57BL/6 mice and the other using leptin receptor-deficient mice (db/db-/-), which became spontaneously obese. After euthanasia, a DNA-DNA hybridization technique was employed to evaluate the microbiota composition and topical application of chlorhexidine (CHX), an antiseptic, was used to investigate the impact of the oral microbiota on the alveolar bone regarding obesity. RESULTS: Increased adipose tissue may induce alveolar bone loss, neutrophil recruitment, and changes in the oral biofilm, similar to that observed in an experimental model of PD. Topical application of CHX impaired bone changes. CONCLUSION: Obesity may induce changes in the oral microbiota and neutrophil recruitment, which are associated with alveolar bone loss.

Dysbiotic oral microbiota contributes to alveolar bone loss associated with obesity in mice

Abstract Periodontal diseases (PD) are inflammatory conditions that affect the teeth supporting tissues. Increased body fat tissues may contribute to activation of the systemic inflammatory response, leading to comorbidities. Some studies have shown that individuals with obesity present higher incidence of PD than eutrophics. Objective: To investigate the impact of obesity on periodontal tissues and oral microbiota in mice. Methodology: Two obesity mice models were performed, one using 12 weeks of the dietary protocol with a high-fat (HF) diet in C57BL/6 mice and the other using leptin receptor-deficient mice (db/db-/-), which became spontaneously obese. After euthanasia, a DNA-DNA hybridization technique was employed to evaluate the microbiota composition and topical application of chlorhexidine (CHX), an antiseptic, was used to investigate the impact of the oral microbiota on the alveolar bone regarding obesity. Results: Increased adipose tissue may induce alveolar bone loss, neutrophil recruitment, and changes in the oral biofilm, similar to that observed in an experimental model of PD. Topical application of CHX impaired bone changes. Conclusion: Obesity may induce changes in the oral microbiota and neutrophil recruitment, which are associated with alveolar bone loss.