Angiotensin-(1-7) Peptide Hormone Reduces Inflammation and Pathogen Burden during Mycoplasma pneumoniae Infection in Mice

The novel pleuromutilin derivative 22-((4-((4-nitrophenyl)acetamido)phenyl)thio)deoxy pleuromutilin possesses robust anti-mycoplasma activity both in vitro and in vivo

Objective

Mycoplasmas are structurally simple pathogenic microorganisms that can cause a wide range of diseases in humans and animals and conventional antibiotic therapies of fluoroquinolones and tetracyclines are toxic to young children and young animals and macrolide resistance is increasing. In this context, new anti-mycoplasma antimicrobial agents need to be developed. 22-((4-((4-nitrophenyl)acetamido)phenyl)thio)deoxypleuromutilin (compound 16C) is a novel acetamine phenyl pleuromutilin derivative. This study aimed to evaluate its acute toxicity in mice and generate pharmacokinetic and anti-mycoplasma profiles.

Methods

The safety of compound 16C was preliminarily evaluated by oral and intramuscular acute toxicity tests and single intravenous and intramuscular pharmacokinetic experiments were performed to obtain its pharmacokinetic profile. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and time-killing curves reflected the in vitro effects of the compounds against Mycoplasma pneumoniae. Five groups consisted of three treatments for compound 16C (20, 40, and 80 mg/kg), and two treatments for tiamulin (oral and intramuscular 40 mg/kg) were continued for 4 d. Bronchoalveolar lavage fluid (BALF) and lung tissues were collected at the end of treatment (96 h) and 4 days later (192 h) to assess the in vivo anti-mycoplasma and anti-pneumonia effects. ELISA assays were performed to detect IFN-γ, TNF-α, and IL-8 (CXCL1) in BALF. Lung tissues were fixed with 4% paraformaldehyde and sectioned for histopathological assessment.

Results

The results show that compound 16C has low toxicity (LD50 > 5,000 mg/kg). Its pharmacokinetic profile is characterized by a short time to maximum concentration (Tmax = 0.24 h), high bioavailability (F = 71.29%), and short elimination half-life (T1/2kel) (intramuscular and intravenous administration was 2.20 and 1.89 h, respectively). Treatment with compound 16C and intramuscular tiamulin reduced the mycoplasma load in mice. Intramuscular compound 16C and tiamulin also inhibited the release of IFN-γ, TNF-α, and CXCL1, decreasing the accumulation of inflammatory cells in the lungs, thereby mitigating lung damage.

Conclusion

This study proved that compound 16C has a strong antimicrobial effect against M. pneumoniae, can be rapidly absorbed and has therapeutic efficacy that provides a basis for developing new anti-mycoplasma drugs.

Intranasal liposomal angiotensin-(1-7) administration reduces inflammation and viral load in the lungs during SARS-CoV-2 infection in K18-hACE2 transgenic mice

To effectively reduce the health impact of coronavirus disease (COVID-19), it is essential to adopt comprehensive strategies to protect individuals from severe acute respiratory syndrome. In that sense, much effort has been devoted to the discovery and repurposing of effective antiviral and anti-inflammatory molecules. The endogenous peptide angiotensin-(1-7) [Ang-(1-7)] has been recently proposed as a promising anti-inflammatory agent to control respiratory infections. Liposomes also emerged as a safe and effective drug carrier system for local drug delivery to the lungs. In this context, the aim of this study was to develop a liposomal formulation of Ang-(1-7) [LAng (1-7)] and investigate its impact on animal survival as well as its antiviral and anti-inflammatory efficacies after intranasal administration in transgenic K18-hACE2 mice infected with SARS-CoV-2. The liposomal formulation was prepared by the ethanol injection method, exhibiting a mean diameter of 100 nm and a polydispersity index of 0.1. Following treatment of infected mice every 12 hours for 5 days, LAng (1-7) extended animal survival compared to the control groups that received either empty liposomes, free Ang-(1-7), or phosphate-buffered saline. Furthermore, the treatment with LAng (1-7) significantly decreased the viral load, as well as IL-6 and tumor necrosis factor levels in the lungs. Conventional treatment with remdesivir by parenteral route used as a positive control promoted similar effects, leading to improved survival rates and reduced viral load in the lungs without significant effects on IL-6 level. In conclusion, liposomal Ang-(1-7) emerges as a promising formulation to improve the treatment and decrease the severity of respiratory infections, such as COVID-19.

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.

The angiotensin-(1-7)/MasR axis improves pneumonia caused by Pseudomonas aeruginosa: Extending the therapeutic window for antibiotic therapy

Pseudomonas aeruginosa is a frequent cause of antimicrobial-resistant hospital-acquired pneumonia, especially in critically ill patients. Inflammation triggered by P. aeruginosa infection is necessary for bacterial clearance but must be spatially and temporally regulated to prevent further tissue damage and bacterial dissemination. Emerging data have shed light on the pro-resolving actions of angiotensin-(1-7) [Ang-(1-7)] signaling through the G protein-coupled receptor Mas (MasR) during infections. Herein, we investigated the role of the Ang-(1-7)/Mas axis in pneumonia caused by P. aeruginosa by using genetic and pharmacological approach and found that Mas receptor-deficient animals developed a more severe form of pneumonia showing higher neutrophilic infiltration into the airways, bacterial load, cytokines, and chemokines production and more severe pulmonary damage. Conversely, treatment of pseudomonas-infected mice with Ang-(1-7) was able to decrease neutrophilic infiltration in airways and lungs, local and systemic levels of pro-inflammatory cytokines and chemokines, and increase the efferocytosis rates, mitigating lung damage/dysfunction caused by infection. Notably, the therapeutic association of Ang-(1-7) with antibiotics improved the survival rates of mice subjected to lethal inoculum of P. aeruginosa, extending the therapeutic window for imipenem. Mechanistically, Ang-(1-7) increased phagocytosis of bacteria by neutrophils and macrophages to accelerate pathogen clearance. Altogether, harnessing the Ang-(1-7) pathway during infection is a potential strategy for the development of host-directed therapies to promote mechanisms of resistance and resilience to pneumonia.

LINC02605 involved in paediatric Mycoplasma pneumoniae pneumonia complicated with diarrhoea via miR-539-5p/CXCL1 axis

BACKGROUND

To investigate the involvement of LINC02605 in the progression of paediatric Mycoplasma pneumoniae pneumonia (MPP).

METHODS

One hundred and thirty-two children with MPP (90 simple MPP and 42 MPP + diarrhoea) were enrolled, and their plasma was collected for detection of LINC026505 expression. CCK-8 kit and commercial apoptosis kit were introduced to determine cell growth and apoptosis. In silico prediction analyses were conducted to predict the downstream miRNA for LINC02605, following verification by dual luciferase reporter assay. The lipid-associated membrane proteins (LAMPs) were used to treat A549 and Coca-2 cells.

RESULTS

LIN02605 was highly expressed in the MPP, especially in MPP complicated with diarrhoea. LINC02605 downregulation in A549 cells correlated with significant suppression of cell apoptosis rate and growth inhibition rate in vitro. Introduction of miR-539-5p inhibited luciferase activity in a reporter system containing the wild-type LINC02605 and CXCL1. After stimulation with LAMPs, overexpression of LINC02605 and CXCL1 and inhibition of miR-539-5p were found. miR-539-5p and CXCL1 knockdown resulted in a rescue effect on the LINC02605-inhibited cell apoptosis. LAMPs induced IL-1β in intestinal epithelial cells and IL-1β induced LINC02605 expression in A549 cells.

CONCLUSIONS

LINC02605 was upregulated in MPP and miR-539-5p was a target for LINC02605. LINC02605 may be involved in the crosstalk between the gastrointestinal tract and the respiratory tract.

Renin-angiotensin system inhibitors positively impact on multiple aging regulatory pathways: Could they be used to protect against human aging?

The renin-angiotensin system (RAS)-a classical blood pressure regulator-largely contributes to healthy organ development and function. Besides, RAS activation promotes age-related changes and age-associated diseases, which are attenuated/abolished by RAS-blockade in several mammalian species. RAS-blockers also increase rodent lifespan. In previous work, we discussed how RAS-blockade downregulates mTOR and growth hormone/IGF-1 signaling, and stimulates AMPK activity (together with klotho, sirtuin, and vitamin D-receptor upregulation), and proposed that at least some of RAS-blockade's aging benefits are mediated through regulation of these intermediaries and their signaling to mitochondria. Here, we included RAS-blockade's impact on other aging regulatory pathways, that is, TGF-ß, NF-kB, PI3K, MAPK, PKC, Notch, and Wnt, all of which affect mitochondria. No direct evidence is available on RAS/RAS-blockade-aging regulatory pathway-mitochondria interactions. However, existing results allow to conjecture that RAS-blockers neutralize mitochondrial dysfunction by acting on the discussed pathways. The reviewed evidence led us to propose that the foundation is laid for conducting clinical trials aimed at testing whether angiotensin-converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB)-even at subclinical doses-offer the possibility to live longer and in better health. As ACEi and ARB are low cost and well-tolerated anti-hypertension therapies in use for over 35 years, investigating their administration to attenuate/prevent aging effects seems simple to implement.

Advances in Biomarkers for Diagnosis and Treatment of ARDS

Acute respiratory distress syndrome (ARDS) is a common and fatal disease, characterized by lung inflammation, edema, poor oxygenation, and the need for mechanical ventilation, or even extracorporeal membrane oxygenation if the patient is unresponsive to routine treatment. In this review, we aim to explore advances in biomarkers for the diagnosis and treatment of ARDS. In viewing the distinct characteristics of each biomarker, we classified the biomarkers into the following six categories: inflammatory, alveolar epithelial injury, endothelial injury, coagulation/fibrinolysis, extracellular matrix turnover, and oxidative stress biomarkers. In addition, we discussed the potential role of machine learning in identifying and utilizing these biomarkers and reviewed its clinical application. Despite the tremendous progress in biomarker research, there remain nonnegligible gaps between biomarker discovery and clinical utility. The challenges and future directions in ARDS research concern investigators as well as clinicians, underscoring the essentiality of continued investigation to improve diagnosis and treatment.

Diminazene aceturate mitigates cardiomyopathy by interfering with renin-angiotensin system in a septic rat model

Background

There were limited studies investigating treatments of septic cardiomyopathy (SCM), which is a common complication during sepsis. A septic rat model created by cecal ligation and puncture (CLP) was used to investigate the effects of diminazene aceturate (DIZE) in SCM.

Methods

A total of 151 Wistar rats were randomly assigned into the sham, CLP, or CLP + DIZE group. Data evaluated postoperatively at 6, 12, 24, and 48 hours included: cardiac function; plasma concentrations of tumor necrosis factor-alpha (TNF-α), interleukin-6, angiotensin-(1–7) [Ang-(1–7)], angiotensin II (AngII), troponin I, and brain natriuretic peptide; expression levels of myocardial Ang-(1–7), angiotensin-converting enzyme (ACE), ACE2, and angiotensin type 1 and Mas receptors; and histological changes.

Results

We found that the CLP + DIZE group had a lower mortality compared to the CLP group (38.5% versus 61.5%) within 48 h postoperatively, although without statistical significance. In contrast to the sham group, the CLP group had decreased cardiac functions, increased myocardial injuries, and higher TNF-α levels, which were ameliorated in the CLP + DIZE group. Furthermore, administration of DIZE could reverse the decreases of myocardial Ang-(1–7) and ACE2 expressions in the CLP group, which finally minimized the myocardial microstructure disruptions.

Conclusions

It was concluded that DIZE could mitigate the development of SCM and preserve cardiac function during sepsis possibly by interfering with the renin-angiotensin system through promoting myocardial ACE2 expression and restoring local Ang-(1–7) levels.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40360-022-00584-4.

Fucoxanthin, a Marine Carotenoid, Suppresses Mycoplasma pneumoniae-Triggered Inflammatory Cytokine Production and Promotes Bacterial Clearance in a Murine Model

Mycoplasma pneumoniae (MP), an atypical bacterium, is a common pathogenetic organism of respiratory infection in children. In the present study, we analyzed the beneficial role of fucoxanthin (Fx), a marine carotenoid, in a murine model of MP. C57BL/6 mice were inoculated once intranasally with 107 CFU of M. pneumoniae, and we found that Fx treatment markedly decreased BAL (quantitative bronchoalveolar lavage) M. pneumoniae concentrations and alleviated airway obstruction in the infected mice. Moreover, the concentrations of proinflammatory cytokines, including IL-6, TNF-α and IL-1β, were significantly decreased by Fx treatment in the BAL samples of infected mice. In vitro study further indicated that Fx treatment markedly suppressed the production of proinflammatory cytokines in mouse peritoneal macrophages after M. pneumoniae infection. In conclusion, this may be the first study to report the protective role of Fx against M. pneumoniae infection, providing a potential therapeutic agent for MP.

Pro-resolving therapies as potential adjunct treatment for infectious diseases: Evidence from studies with annexin A1 and angiotensin-(1-7)

Infectious diseases, once believed to be an eradicable public health threat, still represent a leading cause of death worldwide. Environmental and social changes continuously favor the emergence of new pathogens and rapid dissemination around the world. The limited availability of anti-viral therapies and increased antibiotic resistance has made the therapeutic management of infectious disease a major challenge. Inflammation is a primordial defense to protect the host against invading microorganisms. However, dysfunctional inflammatory responses contribute to disease severity and mortality during infections. In recent years, a few studies have examined the relevance of resolution of inflammation in the context of infections. Inflammation resolution is an active integrated process transduced by several pro-resolving mediators, including Annexin A1 and Angiotensin-(1-7). Here, we examine some of the cellular and molecular circuits triggered by pro-resolving molecules and that may be beneficial in the context of infectious diseases.