Angiotensin-converting enzyme 2/angiotensin-(1-7)/Mas axis protects against lung fibrosis by inhibiting the MAPK/NF-κB pathway

TXM-CB13 Improves the Intestinal Mucosal Barrier and Alleviates Colitis by Inhibiting the ROS/TXNIP/TRX/NLRP3 and TLR4/MyD88/NF-κB/NLRP3 Pathways

The activation of inflammasomes (NLRP3 and NLRP1) is central to the pathogenesis of inflammatory bowel disease (IBD). Here we examined the protective effects of a thioredoxin-mimetic peptide CB13 (TXM-CB13), known for its antioxidative stress and anti-inflammatory properties. We examined the effects of TXM-CB13 on dextran sulfate sodium (DSS)-induced colitis and lipopolysaccharide (LPS)-induced NLRP3 inflammasome activation in RAW264.7 macrophages. TXM-CB13 appeared to alleviate symptoms of DSS-induced colitis and to significantly suppress the protein and mRNA levels of NLRP3, Mlck, and IL-1β in colonic tissues. Additionally, TXM-CB13 treatment increased the levels of the intestinal barrier proteins Occludin, ZO-1, and NLRP1, as shown through immunohistochemistry and Western blot analysis. In vitro, TXM-CB13 inhibited LPS-induced TLR4 signaling, reducing MyD88 levels and consequently attenuating the activation of the NF-κB pathways, including p-IκB-α/IκB-α and p-NF-κB-p65/NF-κB-p65. This inhibition further reduced the activation of the NLRP3 inflammasome components, NLRP3, ASC, Caspase-1, GSDMD, and IL-1β. In addition, TXM-CB13 prevented the ROS-mediated dissociation of TXNIP from TRX, inhibiting NLRP3 activation. These findings suggest that TXM-CB13 is a potential therapeutic candidate for IBD through its modulation of the TLR4/MyD88/NF-κB/NLRP3 and ROS/TXNIP/TRX/NLRP3 pathways.

Accuracy study of Angiotensin 1-7 composite index test to predict pulmonary fibrosis and guide treatment

BACKGROUND

Pulmonary fibrosis can develop after acute respiratory distress syndrome (ARDS). The hypothesis is we are able to measure phenotypes that lie at the origin of ARDS severity and fibrosis development. The aim is an accuracy study of prognostic circulating biomarkers.

METHODS

A longitudinal study followed COVID-related ARDS patients with medical imaging, pulmonary function tests and biomarker analysis, generating 444 laboratory data. Comparison to controls used non-parametrical statistics; p < 0·05 was considered significant. Cut-offs were obtained through receiver operating curve. Contingency tables revealed predictive values. Odds ratio was calculated through logistic regression.

RESULTS

Angiotensin 1-7 beneath 138 pg/mL defined Angiotensin imbalance phenotype. Hyper-inflammatory phenotype showed a composite index test above 34, based on high Angiotensin 1-7, C-Reactive Protein, Ferritin and Transforming Growth Factor-β. Analytical study showed conformity to predefined goals. Clinical performance gave a positive predictive value of 95 % (95 % confidence interval, 82 %-99 %), and a negative predictive value of 100 % (95 % confidence interval, 65 %-100 %). Those severe ARDS phenotypes represented 34 (Odds 95 % confidence interval, 3-355) times higher risk for pulmonary fibrosis development (p < 0·001).

CONCLUSIONS

Angiotensin 1-7 composite index is an early and objective predictor of ARDS evolving to pulmonary fibrosis. It may guide therapeutic decisions in targeted phenotypes.

Steroid hormones in systemic sclerosis: associations with disease characteristics and modifications during scleroderma renal crisis

OBJECTIVE

The renin-angiotensin-aldosterone system (RAAS) and glucocorticoids (GCs) are involved in vascular remodeling and fibrosis but have not been extensively studied in systemic sclerosis (SSc). Our aim was to investigate the RAAS and GC hormones in SSc patients.

METHODS

Serum levels of renin (dosage and activity), aldosterone and its precursors (DOC, B, 18-OH-DOC, 18-OH-B), and GCs (cortisol, cortisone, 11-deoxycortisol, 18-OH-F) were assessed in 122 SSc patients and 52 healthy controls. After applying stringent inclusion criteria aimed at ensuring accurate hormone assessments (exclusion of interfering drugs, strict sampling conditions), we analysed RAAS hormones in 61 patients, and GCs in 96 patients. Hormone levels were compared between patients and controls; and associations with disease characteristics were assessed in patients.

RESULTS

Regarding RAAS hormones, SSc patients displayed significantly lower aldosterone levels (although within normal range), similar renin levels, and higher B levels than controls. Abnormal RAAS hormone levels were associated with a more severe SSc phenotype (lung and skin fibrosis, heart and pulmonary vascular involvements, inflammation). Regarding GC hormones, SSc patients had higher levels of cortisol, 11-desoxycortisol (precursor) and 18-OH-F (metabolite) but lower levels of cortisone (inactive counterpart) than controls. RAAS hormone levels were assessed in five SSc patients before and during scleroderma renal crisis (SRC): concentrations varied considerably between patients, but consistently included normal/increased aldosterone levels and elevated renin levels.

CONCLUSION

RAAS and GC hormones are abnormally produced in SSc patients, especially in patients with severe SSc and during SRC. This could suggest a participation of these hormonal systems in SSc pathogenesis.

Effects of hemodynamic load on cardiac remodeling in fish and mammals: the value of comparative models

The ability of the vertebrate heart to remodel enables the cardiac phenotype to be responsive to changes in physiological conditions and aerobic demand. Examples include exercise-induced cardiac hypertrophy, and the significant remodeling of the trout heart during thermal acclimation. Such changes are thought to occur in response to a change in hemodynamic load (i.e. the forces that the heart must work against to circulate blood). Variations in hemodynamic load are caused by either a volume overload (high volume of blood returning to the heart, impairing contraction) or a pressure overload (elevated afterload pressure that the heart must contract against). The changes observed in the heart during remodeling are regulated by multiple cellular signaling pathways. The cardiac response to these regulatory mechanisms occurs across levels of biological organization, affecting cardiac morphology, tissue composition and contractile function. Importantly, prolonged exposure to pressure overload can cause a physiological response - that improves function - to transition to a pathological response that causes loss of function. This Review explores the role of changes in hemodynamic load in regulating the remodeling response, and considers the cellular signals responsible for regulating remodeling, incorporating knowledge gained from studying biomedical models and comparative animal models. We specifically focus on the renin-angiotensin system, and the role of nitric oxide, oxygen free radicals and transforming growth factor beta. Through this approach, we highlight the strong conservation of the regulatory pathways of cardiac remodeling, and the specific conditions within endotherms that may be conducive to the development of pathological phenotypes.

Possible mechanisms of SARS-CoV-2-associated myocardial fibrosis: reflections in the post-pandemic era

Since December 2019, coronavirus disease 2019 (COVID-19) has been spreading worldwide with devastating immediate or long-term effects on people's health. Although the lungs are the primary organ affected by COVID-19, individuals infected with SARS-CoV-2 also develop systemic lesions involving multiple organs throughout the body, such as the cardiovascular system. Emerging evidence reveals that COVID-19 could generate myocardial fibrosis, termed "COVID-19-associated myocardial fibrosis." It can result from the activation of fibroblasts via the renin-angiotensin-aldosterone system (RAAS), transforming growth factor-β1 (TGF-β1), microRNAs, and other pathways, and can also occur in other cellular interactions with SARS-CoV-2, such as immunocytes, endothelial cells. Nonetheless, to gain a more profound insight into the natural progression of COVID-19-related myocardial fibrosis, additional investigations are necessary. This review delves into the underlying mechanisms contributing to COVID-19-associated myocardial fibrosis while also examining the antifibrotic potential of current COVID-19 treatments, thereby offering guidance for future clinical trials of these medications. Ultimately, we propose future research directions for COVID-19-associated myocardial fibrosis in the post-COVID-19 era, such as artificial intelligence (AI) telemedicine. We also recommend that relevant tests be added to the follow-up of COVID-19 patients to detect myocardial fibrosis promptly.

ACE2 alleviates sepsis-induced cardiomyopathy through inhibiting M1 macrophage via NF-κB/STAT1 signals

Angiotensin-converting enzyme 2 (ACE2), a crucial element of the renin-angiotensin system (RAS), metabolizes angiotensin II into Ang (1-7), which then combines with the Mas receptor (MasR) to fulfill its protective role in various diseases. Nevertheless, the involvement of ACE2 in sepsis-induced cardiomyopathy (SIC) is still unexplored. In this study, our results revealed that CLP surgery dramatically impaired cardiac function accompanied with disruption of the balance between ACE2-Ang (1-7) and ACE-Ang II axis in septic heart tissues. Moreover, ACE2 knockin markedly alleviated sepsis induced RAS disorder, cardiac dysfunction and improved survival rate in mice, while ACE2 knockout significantly exacerbates these outcomes. Adoptive transfer of bone marrow cells and in vitro experiments showed the positive role of myeloid ACE2 by mitigating oxidative stress, inflammatory response, macrophage polarization and cardiomyocyte apoptosis by blocking NF-κB and STAT1 signals. However, the beneficial impacts were nullified by MasR antagonist A779. Collectively, these findings showed that ACE2 alleviated SIC by inhibiting M1 macrophage via activating the Ang (1-7)-MasR axis, highlight that ACE2 might be a promising target for the management of sepsis and SIC patients.

Circulating miRNAs in the Plasma of Post-COVID-19 Patients with Typical Recovery and Those with Long-COVID Symptoms: Regulation of Immune Response-Associated Pathways

Following the acute phase of SARS-CoV-2 infection, certain individuals experience persistent symptoms referred to as long COVID. This study analyzed the patients categorized into three distinct groups: (1) individuals presenting rheumatological symptoms associated with long COVID, (2) patients who have successfully recovered from COVID-19, and (3) donors who have never contracted COVID-19. A notable decline in the expression of miR-200c-3p, miR-766-3p, and miR-142-3p was identified among patients exhibiting rheumatological symptoms of long COVID. The highest concentration of miR-142-3p was found in healthy donors. One potential way to reduce miRNA concentrations is through antibody-mediated hydrolysis. Not only can antibodies possessing RNA-hydrolyzing activity recognize the miRNA substrate specifically, but they also catalyze its hydrolysis. The analysis of the catalytic activity of plasma antibodies revealed that antibodies from patients with long COVID demonstrated lower hydrolysis activity against five fluorescently labeled oligonucleotide sequences corresponding to the Flu-miR-146b-5p, Flu-miR-766-3p, Flu-miR-4742-3p, and Flu-miR-142-3p miRNAs and increased activity against the Flu-miR-378a-3p miRNA compared to other patient groups. The changes in miRNA concentrations and antibody-mediated hydrolysis of miRNAs are assumed to have a complex regulatory mechanism that is linked to gene pathways associated with the immune system. We demonstrate that all six miRNAs under analysis are associated with a large number of signaling pathways associated with immune response-associated pathways.

Curcumin relieves arecoline-induced oral submucous fibrosis via inhibiting the LTBP2/NF-κB axis

BACKGROUND

Submucosal fibrosis (OSF) of the oral cavity is a chronic scarring disease. Arecoline (Are) is the driving factor for the occurrence and deterioration of OSF. Curcumin plays a vital anti-inflammatory role in Are-induced OSF development. However, its potential pharmacological mechanism needs to be elucidated.

METHODS

The relative molecular level was measured via qRT-PCR or Western blot. MTT assay, transwell assay and flow cytometry detected cell proliferation, migration, and apoptosis. The correlation between hypoxia-inducible factor-1α (HIF-1α) and LTBP2 promoter was confirmed through dual-luciferase reporter assay. ELISA was performed to detect inflammatory cytokines levels.

RESULTS

Curcumin alleviated Are-induced oral mucosal fibroblast cells fibrosis by reducing oral mucosa fibroblasts viability, promoting cell apoptosis, suppressing cell migration, and down-regulating the levels of fibrosis markers and inflammatory factors. Curcumin relieved Are-induced OSF via inhibiting HIF-1α. Mechanically, HIF-1α bound to the promoter of LTBP2 to transcriptionally activated LTBP2. LTBP2 knockdown relieved Are-induced OSF, and curcumin down-regulated LTBP2 via inhibiting HIF-1α to relieve Are-induced OSF. Moreover, curcumin decreased NF-κB signal associated proteins via inhibiting LTBP2 to relieve Are-induced OSF.

CONCLUSION

Curcumin reduced the transcription level of LTBP2 by inhibiting HIF-1α, thereby inactivating NF-κB pathway to alleviate Are-induced OSF.

Pharmacological inhibition of the ACE/Ang-2/AT1 axis alleviates mechanical ventilation-induced pulmonary fibrosis

Mechanical ventilation (MV) is an essential therapy for acute respiratory distress syndrome (ARDS) and pulmonary fibrosis. However, it can also induce mechanical ventilation-induced pulmonary fibrosis (MVPF) and the underlying mechanism remains unknown. Based on a mouse model of MVPF, the present study aimed to explore the role of the angiotensin-converting enzyme/angiotensin II/angiotensin type 1 receptor (ACE/Ang-2/AT1R) axis in the process of MVPF. In addition, recombinant angiotensin-converting enzyme 2(rACE2), AT1R inhibitor valsartan, AGTR1-directed shRNA and ACE inhibitor perindopril were applied to verify the effect of inhibiting ACE/Ang-2/AT1R axis in the treatment of MVPF. Our study found MV induced an inflammatory reaction and collagen deposition in mouse lung tissue accompanied by the activation of ACE in lung tissue, increased concentration of Ang-2 in bronchoalveolar lavage fluid (BALF), and upregulation of AT1R in alveolar epithelial cells. The process of pulmonary fibrosis could be alleviated by the application of the ACE inhibitor perindopril, ATIR inhibitor valsartan and AGTR1-directed shRNA. Meanwhile, rACE2 could also alleviate MVPF through the degradation of Ang-2. Our finding indicated the ACE/Ang-2/AT1R axis played an essential role in the pathogenesis of MVPF. Pharmacological inhibition of the ACE/Ang-2/AT1R axis might be a promising strategy for the treatment of MVPF.

Counter-regulatory RAS peptides: new therapy targets for inflammation and fibrotic diseases?

The renin-angiotensin system (RAS) is an important cascade of enzymes and peptides that regulates blood pressure, volume, and electrolytes. Within this complex system of reactions, its counter-regulatory axis has attracted attention, which has been associated with the pathophysiology of inflammatory and fibrotic diseases. This review article analyzes the impact of different components of the counter-regulatory axis of the RAS on different pathologies. Of these peptides, Angiotensin-(1-7), angiotensin-(1-9) and alamandine have been evaluated in a wide variety of in vitro and in vivo studies, where not only they counteract the actions of the classical axis, but also exhibit independent anti-inflammatory and fibrotic actions when binding to specific receptors, mainly in heart, kidney, and lung. Other functional peptides are also addressed, which despite no reports associated with inflammation and fibrosis to date were found, they could represent a potential target of study. Furthermore, the association of agonists of the counter-regulatory axis is analyzed, highlighting their contribution to the modulation of the inflammatory response counteracting the development of fibrotic events. This article shows an overview of the importance of the RAS in the resolution of inflammatory and fibrotic diseases, offering an understanding of the individual components as potential treatments.

GTS-21 attenuates ACE/ACE2 ratio and glycocalyx shedding in lipopolysaccharide-induced acute lung injury by targeting macrophage polarization derived ADAM-17

Acute lung injury (ALI) has received considerable attention in intensive care owing to its high mortality rate. It has been demonstrated that the selective alpha7 nicotinic acetylcholine receptor agonist Gainesville Tokushima scientists (GTS)-21 is promising for treating ALI caused by lipopolysaccharides (LPS). However, the precise underlying mechanism remains unknown. This study aimed to investigate the potential efficacy of GTS-21 in the treatment of ALI. We developed mouse models of ALI and alveolar epithelial type II cells (AT2s) injury following treatment with LPS and different polarized macrophage supernatants, respectively. Pathological changes, pulmonary edema, and lung compliance were assessed. Inflammatory cells count, protein content, and pro-inflammatory cytokine levels were analysed in the bronchoalveolar lavage fluid. The expression of angiotensin-converting enzyme (ACE), ACE2, syndecan-1 (SDC-1), heparan sulphate (HS), heparanase (HPA), exostosin (EXT)-1, and NF-κB were tested in lung tissues and cells. GTS-21-induced changes in macrophage polarization were verified in vivo and in vitro. Polarized macrophage supernatants with or without recombination a disintegrin and metalloproteinase-17 (ADAM-17) and small interfering (si)RNA ADAM-17 were used to verify the role of ADAM-17 in AT2 injury. By reducing pathological alterations, lung permeability, inflammatory response, ACE/ACE2 ratio, and glycocalyx shedding, as well as by downregulating the HPA and NF-κB pathways and upregulating EXT1 expression in vivo, GTS-21 significantly diminished LPS-induced ALI compared to that of the LPS group. GTS-21 significantly attenuated macrophage M1 polarization and augmented M2 polarization in vitro and in vivo. The destructive effects of M1 polarization supernatant can be inhibited by GTS-21 and siRNA ADAM-17. GTS-21 exerted a protective effect against LPS-induced ALI, which was reversed by recombinant ADAM-17. Collectively, GTS-21 alleviates LPS-induced ALI by attenuating AT2s ACE/ACE2 ratio and glycocalyx shedding through the inhibition of macrophage M1 polarization derived ADAM-17.

A cardiotoxicity-eliminated ACE2 variant as a pan-inhibitor against coronavirus cell invasion

Human recombinant ACE2 (hrACE2) has been highly anticipated as a successful COVID-19 treatment; however, its potential to cause cardiac side effects has given rise to many concerns. Here, we developed a cardiotoxicity-eliminated hrACE2 variant, which had four mutation sites within hrACE2 (H345L, H374L, H378L, H505L) and was named as hrACE2-4mu. hrACE2-4mu has a consistent binding affinity with the variant SARS-CoV-2 spike proteins (SPs) and an efficient ability to block SP-induced SARS-CoV-2 entry into cells. In golden hamsters, injection of purified wild-type (WT) hrACE2 rescues the early stages of pneumonia caused by the SPs of the WT, delta, and omicron variants with reduced inflammatory cell infiltration. However, long-term injection of WT hrACE2 induces undesired cardiac fibrosis, as demonstrated by upregulated fibronectin and collagen expression. Our newly developed hrACE2-4mu showed similar protective abilities against a series of coronavirus cell invasions as WT hrACE2, meanwhile it did not cause apparent cardiac side effects. Thus, we generated a cardiotoxicity-eliminated variant of hrACE2 as a pan-inhibitor against coronavirus cell invasion, providing a potential novel strategy for the treatment of COVID-19 and other coronaviruses.

Expression patterns of lncRNA MALAT-1 in SARS-COV-2 infection and its potential effect on disease severity via miR-200c-3p and SIRT1

Downregulating Angiotensin Converting Enzyme2 (ACE2) expression may be a shared mechanism for RNA viruses.

Aim

Evaluate the expressions of ACE2 effectors: the long non-coding RNA 'MALAT-1', the micro-RNA 'miR-200c-3p' and the histone deacetylase 'SIRT1' in SARS-COV-2 patients and correlate to disease severity. Sera samples from 98 SARS-COV-2 patients and 30 healthy control participants were collected. qRT-PCR was used for MALAT-1 and miR-200c-3p expression. SIRT1 was measured using ELISA.

Results

In sera of COVID-19 patients, gene expression of miR-200c-3p is increased while MALAT-1 is decreased. SIRT1 protein level is decreased (P value < 0.001). Findings are accentuated with increased disease severity. Serum MALAT-1, miR-200c-3p and SIRT1 could be used as diagnostic markers at cut off values of 0.04 (95.9 % sensitivity), 5.59 (94.9 % sensitivity, 99 % specificity), and 7.4 (98 % sensitivity) respectively. A novel MALAT-1-miR-200c-3p-SIRT1 pathway may be involved in the regulation of SARS-COV-2 severity.

Exosomes from adipose-derived mesenchymal stem cells improve liver fibrosis by regulating the miR-20a-5p/TGFBR2 axis to affect the p38 MAPK/NF-κB pathway

OBJECTIVE

Human adipose-derived mesenchymal stem cell exosomes (ADSC-Exos) are active constituents for treating liver fibrosis. This paper attempted to preliminarily explain the functional mechanism of ADSC-Exos in liver fibrosis through the p38 MAPK/NF-κB pathway.

METHODS

The cell models of hepatic fibrosis were established by inducing LX-2 cells with TGF-β1. Mouse models of liver fibrosis were established by treating mice with CCl4. The in vivo and in vitro models of liver fibrosis were treated with ADSC-Exos. ADSCs were identified by flow cytometry/Alizarin red/oil red O/alcian blue staining. ADSC-Exos were identified by transmission electron microscopy, nanoparticle tracking analysis, and Western blot. LX-2 cell proliferation/viability were evaluated by MTT/BrdU assays. Exosomes were tracked in vivo and body weight changes in mice were monitored. Hepatic pathological changes were observed by HE/Masson staining. α-SMA/collagen I levels in liver tissues were assessed by immunohistochemistry. HA/PIIINP concentrations were measured using the magnetic particle chemiluminescence method. Liver function was assessed using an automatic analyzer. miR-20a-5p level was measured by RT-qPCR. The mRNA levels of fibrosis markers were determined by RT-qPCR, and their protein levels and levels of MAPK/NF-κB pathway-related proteins, as well as TGFBR2 protein level were measured by Western blot. The P65 nuclear expression in mouse liver tissues was quantified by immunofluorescence.

RESULTS

ADSC-Exos suppressed TGF-β1-induced LX-2 cell proliferation and fibrosis and reduced mRNA and protein levels of fibrosis markers in vitro. ADSC-Exos ameliorated liver fibrosis by inhibiting the p38 MAPK/NF-κB pathway activation. ADSC-Exos inhibited activation of the p38 MAPK/NF-κB pathway via regulating the miR-20a-5p/TGFBR2 axis. The in vivo experiment asserted that ADSC-Exos were mainly distributed in the liver, and ADSC-Exos relieved liver fibrosis in mice, which was evidenced by alleviating decreased body weight, reducing collagen and enhancing liver function, and repressed the activation of the p38 MAPK/NF-κB pathway via the miR-20a-5p/TGFBR2 axis.

CONCLUSION

ADSC-Exos attenuated liver fibrosis by suppressing the activation of the p38 MAPK/NF-κB pathway via the miR-20a-5p/TGFBR2 axis.

Angiotensin-(1-7) attenuates SARS-CoV2 spike protein-induced interleukin-6 and interleukin-8 production in alveolar epithelial cells through activation of Mas receptor

BACKGROUND

SARS-CoV-2 spike proteins (SP) can bind to the human angiotensin-converting enzyme 2 (ACE2) in human pulmonary alveolar epithelial cells (HPAEpiC) and trigger an inflammatory process. Angiotensin-(1-7) may have an anti-inflammatory effect through activation of Mas receptor. This study aims to investigate whether SARS-CoV-2 SP can induce inflammation through ACE2 in the alveolar epithelial cells which can be modulated through angiotensin-(1-7)/Mas receptor axis.

METHODS

HPAEpiC were treated with SARS-CoV-2 SP in the presence or absence of ACE2 antagonist-dalbavancin and Mas receptor agonist-angiotensin-(1-7). Proinflammatory cytokine production (IL-6 and IL-8) were measured at mRNA and protein levels. MAP kinase phosphorylation and transcription factor activation was determined by Western Blot. Mas receptor was blocked by either antagonist (A779) or knockdown (specific SiRNA). Experiments were replicated using A549 cells.

FINDINGS

SARS-CoV-2 SP (5 μg/mL) significantly induced MAP kinase (ERK1/2) phosphorylation, downstream transcription factor (activator protein-1, AP-1) activation and cytokine production (IL-6 and IL-8) at both mRNA and protein levels. Pretreatment with dalbavancin (10 μg/mL), or angiotensin-(1-7) (10 μM) significantly reduced ERK1/2 phosphorylation, AP-1 activation, and cytokine production. However, these angiotensin-(1-7)-related protective effects were significantly abolished by blocking Mas receptor with either antagonist (A799,10 μM) or SiRNA knockdown.

INTERPRETATION

SARS-CoV-2 SP can induce proinflammatory cytokine production, which can be inhibited by either ACE2 antagonist or Mas receptor agonist-angiotensin-(1-7). Angiotensin-(1-7)-related protective effect on cytokine reduction can be abolished by blocking Mas receptor. Our findings suggest that ACE2/angiotensin-(1-7)/Mas axis may serve as a therapeutic target to control inflammatory response triggered by SARS-CoV-2 SP.

Emerging opportunities to treat idiopathic pulmonary fibrosis: Design, discovery, and optimizations of small-molecule drugs targeting fibrogenic pathways

Idiopathic pulmonary fibrosis (IPF) is the most common fibrotic form of idiopathic diffuse lung disease. Due to limited treatment options, IPF patients suffer from poor survival. About ten years ago, Pirfenidone (Shionogi, 2008; InterMune, 2011) and Nintedanib (Boehringer Ingelheim, 2014) were approved, greatly changing the direction of IPF drug design. However, limited efficacy and side effects indicate that neither can reverse the process of IPF. With insights into the occurrence of IPF, novel targets and agents have been proposed, which have fundamentally changed the treatment of IPF. With the next-generation agents, targeting pro-fibrotic pathways in the epithelial-injury model offers a promising approach. Besides, several next-generation IPF drugs have entered phase II/III clinical trials with encouraging results. Due to the rising IPF treatment requirements, there is an urgent need to completely summarize the mechanisms, targets, problems, and drug design strategies over the past ten years. In this review, we summarize known mechanisms, target types, drug design, and novel technologies of IPF drug discovery, aiming to provide insights into the future development and clinical application of next-generation IPF drugs.

Carbon dioxide and MAPK signalling: towards therapy for inflammation

Inflammation, although necessary to fight infections, becomes a threat when it exceeds the capability of the immune system to control it. In addition, inflammation is a cause and/or symptom of many different disorders, including metabolic, neurodegenerative, autoimmune and cardiovascular diseases. Comorbidities and advanced age are typical predictors of more severe cases of seasonal viral infection, with COVID-19 a clear example. The primary importance of mitogen-activated protein kinases (MAPKs) in the course of COVID-19 is evident in the mechanisms by which cells are infected with SARS-CoV-2; the cytokine storm that profoundly worsens a patient's condition; the pathogenesis of diseases, such as diabetes, obesity, and hypertension, that contribute to a worsened prognosis; and post-COVID-19 complications, such as brain fog and thrombosis. An increasing number of reports have revealed that MAPKs are regulated by carbon dioxide (CO2); hence, we reviewed the literature to identify associations between CO2 and MAPKs and possible therapeutic benefits resulting from the elevation of CO2 levels. CO2 regulates key processes leading to and resulting from inflammation, and the therapeutic effects of CO2 (or bicarbonate, HCO3-) have been documented in all of the abovementioned comorbidities and complications of COVID-19 in which MAPKs play roles. The overlapping MAPK and CO2 signalling pathways in the contexts of allergy, apoptosis and cell survival, pulmonary oedema (alveolar fluid resorption), and mechanical ventilation-induced responses in lungs and related to mitochondria are also discussed. Video Abstract.

Genetic variants associated with SARS-CoV-2 infection also affect lung function and asthma severity

Background

Host genetic factors may be associated with COVID-19 unfavourable outcomes. The first genome-wide association study (GWAS) conducted in individuals with respiratory failure due to COVID-19 revealed susceptibility loci close to six genes (SLC6A20, LZTFL1, CCR9, FYCO1, CXCR6 and XCR1) and the ABO blood-group gene. We aimed to investigate how polymorphisms in those genes could relate to lung function and severe asthma in a Brazilian population.

Methods

DNA samples of 784 individuals following the ProAR (Programa para Controle da Asma e Rinite Alérgica da Bahia) were genotyped by the Multi-Ethnic Global Array panel with ∼2 million polymorphisms (Illumina). Polymorphisms in SLC6A20, LZTFL1, CCR9, FYCO1, CXCR6, XCR1 and the ABO blood-group gene were evaluated. Logistic regression for severe asthma, airway obstruction and lack of FEV1 reversibility was performed using PLINK software 1.9, in the additive model and was adjusted for sex, age and PCA-1. Pairwise Linkage disequilibrium analyses were performed using Haploview 4.2. The haplotypes and gene score analyses were performed in the SNPstat tool. In silico functions of polymorphisms were analysed using rSNPbase and RegulomeDB plataforms.

Results

We identified the rs8176733 (G allele) and rs8176725 (A allele) in the ABO blood-group gene as risk factors for severe asthma, lower pulmonary obstruction and lack of FEV1 reversibility. Polymorphisms in CCR9 are risk factors for both severe asthma (A allele of rs34338823) and airway obstruction (A allele of rs6806802). The markers rs13079478 (A allele) and rs75817942 (A allele) in FYCO1 are related to more severe asthma and a lack of FEV1 reversibility, respectively. We identified the A allele of both rs35731912 and rs34338823 in LZTFL1 as risk factors for severe asthma. The marker rs6806802 (C allele) was associated with airway obstruction and rs7614952 (A allele), rs7625839 (G allele) and rs112509260 (A allele) are related to a lack of FEV1 reversibility. The A allele of rs2531747 in the SLC6A20 gene is also associated with severe asthma. Conversely, polymorphisms in XCR1 play a protective role in relation to severe asthma (A allele of rs2036295) and airway obstruction (A allele of rs2036295). Additionally, we found that individuals with a higher number of risk alleles have a greater risk of severe asthma, airway obstruction and FEV1 reversibility.

Conclusion

Our study suggests that polymorphisms in genes associated with respiratory failure in SARS-CoV-2-infected individuals are associated with greater susceptibility to severe asthma and reduced lung function in subjects with asthma.

Synergistic effect of constituent drugs of Baibutang on improving Yin-deficiency pulmonary fibrosis in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Baibutang (BBT) is an ancient prescription for the treatment of pulmonary fibrosis. Previous experiments have shown that BBT had a good therapeutic effect on pulmonary fibrosis. However, there had been no study on the synergy between drugs composed of BBT. Due to the interaction between the constituent drugs, exploring their synergy profile is of great significance for explaining the essence of BBT's efficacy in improving pulmonary fibrosis.

AIM OF THE STUDY

Based on the pharmacodynamic value, this study aimed to explore a method for the evaluation of the synergy profile between constituent drugs in traditional Chinese medicine (TCM) compounds.

MATERIALS AND METHODS

Nine herbs of BBT were divided into Zhikeqingre (ZK), Yangyinyiqi (YY) and Lishijianpi (LS) groups. A rat model of Yin-deficiency pulmonary fibrosis induced by thyroxine-bleomycin was used to evaluate the effects of BBT and the three groups. The pathological changes of lung tissue and the changes of biomarkers associated with fibrosis, Yin-deficiency and water-fluid metabolism were detected. After standardization of pharmacodynamics value (PV), the compatibility coefficient (CC) of the three groups, the relative PV (RPV) and contribution value (CV) of each group on every index were calculated.

RESULTS

The average CC on fibrosis indexes was 0.44, indicating that 44% of the efficacy of BBT came from the synergistic effect of the three groups. ZK group had the highest RPV (0.80) in improving fibrosis indexes such as histopathological changes, α-SMA, collagen-I and renin-angiotensin system. The average CC on Yin-deficiency indexes was 0.25, and YY group had the highest RPV (0.96) in improving deficiency indexes such as body temperature, cAMP/cGMP ratio, and PDEs, PGE2 and COX-2 levels. The average CC on water-fluid metabolism indexes was 0.15, and LS group had the highest RPV (1.52) in improving water-fluid metabolism indexes such as aquaporins, mucins, and surfactant proteins. The results also showed that 29% of the improvement effect of BBT on all indexes came from the synergistic effect of the three groups, and the contribution of ZK, YY and LS groups to the efficacy of BBT were 25%, 25% and 21%, respectively.

CONCLUSION

The established semiquantitative method can clearly and simply evaluate the synergy of the three groups in BBT, which will help to promote the research on the synergy of TCM compounds and other multiple-components combinations.

Targeting the renin angiotensin system for respiratory diseases

Renin-angiotensin system (RAS) plays an indispensable role in regulating blood pressure through its effects on fluid and electrolyte balance. As an aside, cumulative evidence from experimental to clinical studies supports the notion that dysregulation of RAS contributes to the pro-inflammatory, pro-oxidative, and pro-fibrotic processes that occur in pulmonary diseases like asthma, chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), and acute lung injury (ALI). Pharmacological intervention of the various RAS components can be a novel therapeutic strategy for the treatment of these respiratory diseases. In this chapter, we first give a recent update on the RAS, and then compile, review, and analyse recent reports on targeting RAS components as treatments for respiratory diseases. Inhibition of the pro-inflammatory renin, angiotensin-converting enzyme (ACE), angiotensin (Ang) II, and Ang II type 1 receptor (AT1R) axis, and activation of the protective ACE2, AT2R, Ang (1-7), and Mas receptor axis have demonstrated varying degrees of efficacies in experimental respiratory disease models or in human trials. The newly identified alamandine/Mas-related G-protein-coupled receptor member D pathway has shown some therapeutic promise as well. However, our understanding of the RAS ligand-and-receptor interactions is still inconclusive, and the modes of action and signaling cascade mediating the newly identified RAS receptors remain to be better characterized. Clinical data are obviously lacking behind the promising pre-clinical findings of certain well-established molecules targeting at different pathways of the RAS in respiratory diseases. Translational human studies should be the focus for RAS drug development in lung diseases in the next decade.

A Review on COVID-19: Primary Receptor, Endothelial Dysfunction, Related Comorbidities, and Therapeutics

Since December 2019, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has caused a global pandemic named coronavirus disease-19 (COVID-19) and resulted in a worldwide economic crisis. Utilizing the spike-like protein on its surface, the SARS-CoV-2 binds to the receptor angiotensin-converting enzyme 2 (ACE2), which highly expresses on the surface of many cell types. Given the crucial role of ACE2 in the renin–angiotensin system, its engagement by SARS-CoV-2 could potentially result in endothelial cell perturbation. This is supported by the observation that one of the most common consequences of COVID-19 infection is endothelial dysfunction and subsequent vascular damage. Furthermore, endothelial dysfunction is the shared denominator among previous comorbidities, including hypertension, kidney disease, cardiovascular diseases, etc., which are associated with an increased risk of severe disease and mortality in COVID-19 patients. Several vaccines and therapeutics have been developed and suggested for COVID-19 therapy. The present review summarizes the relationship between ACE2 and endothelial dysfunction and COVID-19, also reviews the most common comorbidities associated with COVID-19, and finally reviews several categories of potential therapies against COVID-19.

Human Coronavirus Cell Receptors Provide Challenging Therapeutic Targets

Coronaviruses interact with protein or carbohydrate receptors through their spike proteins to infect cells. Even if the known protein receptors for these viruses have no evolutionary relationships, they do share ontological commonalities that the virus might leverage to exacerbate the pathophysiology. ANPEP/CD13, DPP IV/CD26, and ACE2 are the three protein receptors that are known to be exploited by several human coronaviruses. These receptors are moonlighting enzymes involved in several physiological processes such as digestion, metabolism, and blood pressure regulation; moreover, the three proteins are expressed in kidney, intestine, endothelium, and other tissues/cell types. Here, we spot the commonalities between the three enzymes, the physiological functions of the enzymes are outlined, and how blocking either enzyme results in systemic deregulations and multi-organ failures via viral infection or therapeutic interventions is addressed. It can be difficult to pinpoint any coronavirus as the target when creating a medication to fight them, due to the multiple processes that receptors are linked to and their extensive expression.

The role of autophagy in idiopathic pulmonary fibrosis: from mechanisms to therapies

Idiopathic pulmonary fibrosis (IPF) is an interstitial pulmonary disease with an extremely poor prognosis. Autophagy is a fundamental intracellular process involved in maintaining cellular homeostasis and regulating cell survival. Autophagy deficiency has been shown to play an important role in the progression of pulmonary fibrosis. This review focused on the six steps of autophagy, as well as the interplay between autophagy and other seven pulmonary fibrosis related mechanisms, which include extracellular matrix deposition, myofibroblast differentiation, epithelial-mesenchymal transition, pulmonary epithelial cell dysfunction, apoptosis, TGF-β1 pathway, and the renin-angiotensin system. In addition, this review also summarized autophagy-related signaling pathways such as mTOR, MAPK, JAK2/STAT3 signaling, p65, and Keap1/Nrf2 signaling during the development of IPF. Furthermore, this review also illustrated the commonly used autophagy detection methods, the currently approved antifibrotic drugs pirfenidone and nintedanib, and several prospective compounds targeting autophagy for the treatment of IPF.

Connective tissue disease-related interstitial lung disease is alleviated by tripterine through inhibition of the PI3K/Akt, apoptosis, and TNF-α signalling pathways

Background: Interstitial lung disease (ILD) is the major cause of morbidity and mortality in patients with various rheumatic diseases. However, more interventions need to be sought. Tripterine, an extract of Tripterygium wilfordii Hook. F, has been widely studied for its powerful anti-inflammatory effect. However, its mechanism of action in treating connective tissue disease-related (CTD)-ILD remains unclear.

Purpose: To investigate the mechanism of tripterine in CTD-ILD treatment by combining network pharmacology and an in vivo experiment.

Methods: The related targets of tripterine were obtained after searching the Traditional Chinese Medicine System Pharmacology Database and Analysis Platform, Comparative Toxicogenomics Database, GeneCards, Search Tool for Interacting Chemicals database, and SymMap database. Following this, Online Mendelian Inheritance in Man, GeneCards, Genebank, and DrugBank were used to screen the targets of CTD-ILD. A target-signalling pathway network was constructed using Cytoscape. Additionally, topological analysis was performed. Protein interaction analysis was performed using the STRING online analysis platform. Following this, Gene Ontology (GO) and the Kyoto Encyclopaedia of Genes and Genomes (KEGG) signalling pathway enrichment analyses were performed. Subsequently, the molecular docking between tripterine and the core targets was verified. Finally, experimental verification was performed in bleomycin-induced model mice.

Results: A total of 134 common targets and 10 core targets of tripterine, including signal transducer and activator of transcription 3, tumour necrosis factor (TNF), v-rel avian reticuloendotheliosis viral oncogene homolog A, protein kinase B (Akt) α (Akt1), mitogen-activated protein kinase (MAPK) 1, Jun transcription factor family, tumour protein 53, MAPK3, nuclear factor kappa B subunit 1, and caspase 8, were obtained. GO enrichment analysis revealed that, while treating CTD-ILD, tripterine was mainly involved in cytokine receptor binding, receptor-ligand activity, signal receptor activation, cytokine activity, protein ubiquitination, deoxyribonucleic acid transcriptase activity, etc. The KEGG pathway enrichment analysis revealed that the most significant signalling pathways were multiple viral infections and the phosphatidylinositol-3-kinase (PI3K)/Akt, TNF, and apoptosis signalling pathways. Molecular docking results revealed that tripterine had good docking activity with the core targets. Experimental studies also demonstrated that tripterine could inhibit the activation of PI3K/Akt, apoptosis, and TNF-α signalling pathways in lung tissue and significantly improve lung pathology and collagen deposition in the model mice.

Conclusions: This study preliminarily revealed the potential molecular biological mechanism of tripterine while treating CTD-ILD might be related to inhibiting the PI3K/Akt, apoptosis, and TNF-α signalling pathways. Tripterygium wilfordii Hook. F. and its extract could be used clinically for treating CTD-ILD.

MIR99AHG inhibits EMT in pulmonary fibrosis via the miR-136-5p/USP4/ACE2 axis

Background

Long non-coding RNAs (lncRNAs) are closely related to the occurrence and development of cancer. Abnormally expressed lncRNA can be used as a diagnostic marker for cancer. In this study, we aim to investigate the clinical significance of MIR99AHG expression in lung adenocarcinoma (LUAD), and its biological roles in LUAD progression.

Methods

The relative expression of MIR99AHG in LUAD tissues and cell lines was analyzed using public databases and RT-qPCR. The biological functions of MIR99AHG were investigated using a loss-of-function approach. The effect of MIR99AHG on lung fibrosis was assessed by scratch assay, invasion assay and lung fibrosis rat model. FISH, luciferase reporter assay and immunofluorescence were performed to elucidate the underlying molecular mechanisms.

Results

LncRNA MIR99AHG expression level was downregulated in LUAD tissues and cell lines. Low MIR99AHG levels were associated with poorer patient overall survival. Functional analysis showed that MIR99AHG is associated with the LUAD malignant phenotype in vitro and in vivo. Further mechanistic studies showed that, MIR99AHG functions as a competitive endogenous RNA (ceRNA) to antagonize miR-136-5p-mediated ubiquitin specific protease 4 (USP4) degradation, thereby unregulated the expression of angiotensin-converting enzyme 2 (ACE2), a downstream target gene of USP4, which in turn affected alveolar type II epithelial cell fibrosis and epithelial–mesenchymal transition (EMT). In summary, the MIR99AHG/miR-136-5p/USP4/ACE2 signalling axis regulates lung fibrosis and EMT, thus inhibiting LUAD progression.

Conclusion

This study showed that downregulated MIR99AHG leads to the development of pulmonary fibrosis. Therefore, overexpression of MIR99AHG may provide a new approach to preventing LUAD progression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03633-y.

The Pretreatment of Xiaoqinglong Decoction Alleviates Inflammation and Oxidative Damage and Up-Regulates Angiotensin-Converting Enzyme 2 in Lipopolysaccharide-Induced Septic Acute Lung Injury Rats

Xiaoqinglong decoction (XQLD), a classic prescription of Traditional Chinese Medicine, has already been used clinically to cure acute lung injury (ALI), but its mechanism remains unclear. This subject aimed to explore the preventive role of XQLD in septic ALI rats besides its effects on angiotensin-converting enzyme (ACE)2 and its downstream factors. After, respectively, administrated with different concentrations of XQLD (6.25 g/kg/d, 12.5 g/kg/d, 25 g/kg/d) for 5 days and dexamethasone (DEX, 1 mg/kg) for 0.5 h, the rat models of ALI were established by intraperitoneal injection of lipopolysaccharide (LPS, 5 mg/kg) for 24 h. All rats were evaluated by lung function test, arterial blood gas analysis, morphological observation, lung wet/dry (W/D) ratio, and the lung injury score. The levels of malonaldehyde (MDA), superoxide dismutase (SOD), interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and angiotensin (Ang) (1–7) in the lung were measured through biochemical and ELISA kits. The expressions of angiotensin-converting enzyme (ACE)2, mitochondrial assembly receptor (MasR), and nuclear factor (NF)-κB in lung tissue were detected by qRT-PCR and western blotting. Positive reaction cells of MasR were observed by immunohistochemistry. The results show that XQLD significantly ameliorated septic lung injury including edema and hemorrhage, as well as improved pulmonary function and arterial blood gas. Furthermore, XQLD markedly decreased the levels of IL-1β, TNF-α, MDA, and NF-κB while increased the levels of SOD, Ang (1–7), ACE2, and MasR in septic ALI rats. Pearson correlation showed that the expressions of ACE2 were inversely related to IL-1β, TNF-α, MDA, and NF-κB and positively correlated with SOD contents. Our data indicated that XQLD pretreatment alleviated inflammation and oxidative damage in septic ALI rats, which might be related to the up-regulation of ACE2-Ang (1–7)-MasR axis and inhibition of the NF-κB pathway.

Caffeine Inhibits NLRP3 Inflammasome Activation by Downregulating TLR4/MAPK/NF-κB Signaling Pathway in an Experimental NASH Model

Caffeine elicits protective effects against liver diseases, such as NASH; however, its mechanism of action involving the pyrin domain-containing-3 (NLRP3) inflammasome signaling pathway remains to be elucidated. This study aimed to evaluate the effect of caffeine on the NLRP3 inflammasome signaling pathway in a rat model of NASH. NASH was induced by feeding rats a high-fat, -sucrose, and -cholesterol diet (HFSCD) for 15 weeks along with a weekly low dose (400 mg/kg, i.p.) of CCl₄. Caffeine was administered at 50 mg/kg p.o. The effects of HFSCD+CCl₄ and caffeine on the liver were evaluated using biochemical, ultrastructural, histological, and molecular biological approaches. The HFSCD+CCl₄-treated rats showed fat accumulation in the liver, elevated levels of inflammatory mediators, NLRP3 inflammasome activation, antioxidant dysregulation, and liver fibrosis. Caffeine reduced necrosis, cholestasis, oxidative stress, and fibrosis. Caffeine exhibited anti-inflammatory effects by attenuating NLRP3 inflammasome activation. Moreover, caffeine prevented increases in toll-like receptor 4 (TLR4) and nuclear factor-κB (NF-κB) protein levels and mitigated the phosphorylation of mitogen-activated protein kinase (MAPK). Importantly, caffeine prevented the activation of hepatic stellate cells. This study is the first to report that caffeine ameliorates NASH by inhibiting NLRP3 inflammasome activation through the suppression of the TLR4/MAPK/NF-κB signaling pathway.

Network analysis for elucidating the mechanisms of Shenfu injection in preventing and treating COVID-19 combined with heart failure

BACKGROUND

The emergence of the novel coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to millions of infections and is exerting an unprecedented impact on society and economies worldwide. The evidence showed that heart failure (HF) is a clinical syndrome that could be encountered at different stages during the progression of COVID-19. Shenfu injection (SFI), a traditional Chinese medicine (TCM) formula has been widely used for heart failure therapy in China and was suggested to treat critical COVID-19 cases based on the guideline for diagnosis and treatment of COVID-19 (the 7th version) issued by National Health Commission of the People's Republic of China. However, the active components, potential targets, related pathways, and underlying pharmacology mechanism of SFI against COVID-19 combined with HF remain vague.

OBJECTIVE

To investigate the effectiveness and possible pharmacological mechanism of SFI for the prevention and treatment of COVID-19 combined with HF.

METHODS

In the current study, a network analysis approach integrating active compound screening (drug-likeness, lipophilicity, and aqueous solubility models), target fishing (Traditional Chinese Medicine Systems Pharmacology, fingerprint-based Similarity Ensemble Approach, and PharmMapper databases), compound-target-disease network construction (Cytoscape software), protein-protein interaction network construction (STRING and Cytoscape software), biological process analysis (STRING and Cytoscape plug-in Clue GO) and pathway analysis (Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis) was developed to decipher the active ingredients, potential targets, relevant pathways, and the therapeutic mechanisms of SFI for preventing and treating COVID-19 combined with HF.

RESULTS

Finally, 20 active compounds (DL ≥ 0.18, 1≤Alog P ≤ 5, and -5≤LogS ≤ -1) and 164 relevant targets of SFI were identified related to the development of COVID-19 combined with HF, which were mainly involved in three biological processes including metabolic, hemostasis, and cytokine signaling in immune system. The C-T-D network and reactome pathway analysis indicated that SFI probably regulated the pathological processes of heart failure, respiratory failure, lung injury, and inflammatory response in patients with COVID-19 combined with HF through acting on several targets and pathways. Moreover, the venn diagram was used to identify 54 overlapped targets of SFI, COVID-19, and HF. KEGG pathway enrichment analysis showed that 54 overlapped targets were highly enriched to several COVID-19 and HF related pathways, such as IL-17 signaling pathway, Th17 cell differentiation, and NF-kappa B signaling pathway.

CONCLUSIONS

A comprehensive network analysis approach framework was developed to systematically elucidate the potential pharmacological mechanism of SFI for the prevention and treatment of SFI against COVID-19 combined with HF. The current study may not only provide in-depth understanding of the pharmacological mechanisms of SFI, but also a scientific basis for the application of SFI against COVID-19 combined with HF.

Recombinant ACE2 protein protects against acute lung injury induced by SARS-CoV-2 spike RBD protein

BACKGROUND

SARS-CoV-2 infection leads to acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Both clinical data and animal experiments suggest that the renin-angiotensin system (RAS) is involved in the pathogenesis of SARS-CoV-2-induced ALI. Angiotensin-converting enzyme 2 (ACE2) is the functional receptor for SARS-CoV-2 and a crucial negative regulator of RAS. Recombinant ACE2 protein (rACE2) has been demonstrated to play protective role against SARS-CoV and avian influenza-induced ALI, and more relevant, rACE2 inhibits SARS-CoV-2 proliferation in vitro. However, whether rACE2 protects against SARS-CoV-2-induced ALI in animal models and the underlying mechanisms have yet to be elucidated.

METHODS AND RESULTS

Here, we demonstrated that the SARS-CoV-2 spike receptor-binding domain (RBD) protein aggravated lipopolysaccharide (LPS)-induced ALI in mice. SARS-CoV-2 spike RBD protein directly binds and downregulated ACE2, leading to an elevation in angiotensin (Ang) II. AngII further increased the NOX1/2 through AT1R, subsequently causing oxidative stress and uncontrolled inflammation and eventually resulting in ALI/ARDS. Importantly, rACE2 remarkably reversed SARS-CoV-2 spike RBD protein-induced ALI by directly binding SARS-CoV-2 spike RBD protein, cleaving AngI or cleaving AngII.

CONCLUSION

This study is the first to prove that rACE2 plays a protective role against SARS-CoV-2 spike RBD protein-aggravated LPS-induced ALI in an animal model and illustrate the mechanism by which the ACE2-AngII-AT1R-NOX1/2 axis might contribute to SARS-CoV-2-induced ALI.

An Inhibitor of Nuclear Factor-Kappa B Pathway Attenuates the Release of TGF-β1 and Inhibits the Fibrogenic Progress in a Model of Airway Remodeling Induced by Acrolein

Airway inflammation, airway hypersecretion, and airway remodeling are believed to be involved in the process of lung fibrosis. Nowadays, acrolein is widely used to establish the model of airway remodeling. An active component of propolis, named caffeic acid phenethyl ester (CAPE), is recognized as an inhibitor of the NF-κB pathway and shows anti-inflammatory effect. The purpose of this study was to investigate the protective effect of CAPE on acrolein-induced airway remodeling. 24 mice were divided into 4 groups: control group; acrolein group, mice received acrolein (inhalation of acrolein for 20 days); CAPE group, mice received CAPE (30 mg/kg); and acrolein+CAPE group, mice received acrolein and CAPE. After 20 days, lung tissue was removed for histopathology and immunohistochemical evaluations. TGF-β1 and Muc5ac levels were measured at the protein and molecular levels. Additionally, the phospho-P65/P65 values in the airway smooth muscle cells treated with TGF-β1 or CAPE were detected by Western blot. The results showed that compared with the control, subepithelial collagen deposition, airway inflammation, and peribronchus fibrosis were inhibited in the group treated with CAPE. Furthermore, TGF-β1 was significantly decreased in the acrolein+CAPE group compared with the acrolein group. Additionally, we identified CAPE inhibited P65 phosphorylation. However, CAPE did not inhibit the Muc5ac overproduction and hypersecretion induced by acrolein. In conclusion, as an inhibitor of the NF-κB pathway, CAPE attenuated the release of TGF-β1_, which inhibited the fibrogenic progress induced by acrolein in mice and took no effect on inhibiting airway mucus hypersecretion.

Role of the renin-angiotensin system in NETosis in the coronavirus disease 2019 (COVID-19)

Myocardial infarction and stroke are the leading causes of death in the world. Numerous evidence has confirmed that hypertension promotes thrombosis and induces myocardial infarction and stroke. Recent findings reveal that neutrophil extracellular traps (NETs) are involved in the induction of myocardial infarction and stroke. Meanwhile, patients with severe COVID-19 suffer from complications such as myocardial infarction and stroke with pathological signs of NETs. Due to the extremely low amount of virus detected in the blood and remote organs (e.g., heart, brain and kidney) in a few cases, it is difficult to explain the mechanism by which the virus triggers NETosis, and there may be a different mechanism than in the lung. A large number of studies have found that the renin-angiotensin system regulates the NETosis at multiple levels in patients with COVID-19, such as endocytosis of SARS-COV-2, abnormal angiotensin II levels, neutrophil activation and procoagulant function at multiple levels, which may contribute to the formation of reticular structure and thrombosis. The treatment of angiotensin-converting enzyme inhibitors (ACEI), angiotensin II type 1 receptor blockers (ARBs) and neutrophil recruitment and active antagonists helps to regulate blood pressure and reduce the risk of net and thrombosis. The review will explore the possible role of the angiotensin system in the formation of NETs in severe COVID-19.

Latent Transforming Growth Factor-β Binding Protein-2 Regulates Lung Fibroblast-to-Myofibroblast Differentiation in Pulmonary Fibrosis via NF-κB Signaling

Despite past extensive studies, the mechanisms underlying pulmonary fibrosis (PF) still remain poorly understood. The aberrantly activated lung myofibroblasts, predominantly emerging through fibroblast-to-myofibroblast differentiation, are considered to be the key cells in PF, resulting in excessive accumulation of extracellular matrix (ECM). Latent transforming growth factor-β (TGFβ) binding protein-2 (LTBP2) has been suggested as playing a critical role in modulating the structural integrity of the ECM. However, its function in PF remains unclear. Here, we demonstrated that lungs originating from different types of patients with PF, including idiopathic PF and rheumatoid arthritis-associated interstitial lung disease, and from mice following bleomycin (BLM)-induced PF were characterized by increased LTBP2 expression in activated lung fibroblasts/myofibroblasts. Moreover, serum LTBP2 was also elevated in patients with COVID-19-related PF. LTBP2 silencing by lentiviral shRNA transfection protected against BLM-induced PF and suppressed fibroblast-to-myofibroblast differentiation in vivo and in vitro. More importantly, LTBP2 overexpression was able to induce differentiation of lung fibroblasts to myofibroblasts in vitro, even in the absence of TGFβ1. By further mechanistic analysis, we demonstrated that LTBP2 silencing prevented fibroblast-to-myofibroblast differentiation and subsequent PF by suppressing the phosphorylation and nuclear translocation of NF-κB signaling. LTBP2 overexpression-induced fibroblast-to-myofibroblast differentiation depended on the activation of NF-κB signaling in vitro. Therefore, our data indicate that intervention to silence LTBP2 may represent a promising therapy for PF.

Pulmonary Hypertension Is Associated With Systemic Arterial Hypertension Among Patients With Normal Left Ventricular Diastolic Function

Background

The association of pulmonary and systemic arterial hypertension is believed to be mediated through hypertensive left heart disease. The purpose of the current study was to investigate whether pulmonary hypertension (PHT) is associated with systemic arterial hypertension among patients with apparently normal left ventricular diastolic function.

Methods and Results

Consecutive patients who had echocardiographic evaluation between 2007 and 2019 were enrolled. Patients with disease states that are known to be associated with PHT, including diastolic dysfunction, were excluded from the analysis. Estimated right ventricular systolic pressure was extracted for all patients from the echocardiographic reports. PHT was defined as estimated right ventricular systolic pressure >40 mm Hg. Multivariate logistic regression models were applied. Final study population included 25 916 patients with a median age of 59 (interquartile range, 44–69) years, of whom 12 501 (48%) were men and 13 265 (51%) had systemic arterial hypertension. Compared with normotensive patients, hypertensive patients were 3.2 times more likely to have PHT (95% CI, 2.91–3.53; P<0.001). A multivariate model adjusted for clinical and echocardiographic parameters that are known to be associated with PHT demonstrated that hypertensive patients are almost 3 times more likely to have PHT (95% CI, 2.45–3.15; P<0.001). The association was significant in multiple subgroups but was more significant among women compared with men (odds ratio, 3.1 versus 2.4; P for interaction <0.001).

Conclusions

PHT is associated with systemic arterial hypertension irrespective of left heart disease. The association is more pronounced among women.

Virus infection induced pulmonary fibrosis

Pulmonary fibrosis is the end stage of a broad range of heterogeneous interstitial lung diseases and more than 200 factors contribute to it. In recent years, the relationship between virus infection and pulmonary fibrosis is getting more and more attention, especially after the outbreak of SARS-CoV-2 in 2019, however, the mechanisms underlying the virus-induced pulmonary fibrosis are not fully understood. Here, we review the relationship between pulmonary fibrosis and several viruses such as Human T-cell leukemia virus (HTLV), Human immunodeficiency virus (HIV), Cytomegalovirus (CMV), Epstein–Barr virus (EBV), Murine γ-herpesvirus 68 (MHV-68), Influenza virus, Avian influenza virus, Middle East Respiratory Syndrome (MERS)-CoV, Severe acute respiratory syndrome (SARS)-CoV and SARS-CoV-2 as well as the mechanisms underlying the virus infection induced pulmonary fibrosis. This may shed new light on the potential targets for anti-fibrotic therapy to treat pulmonary fibrosis induced by viruses including SARS-CoV-2.

Pathogenesis and Mechanism of Gastrointestinal Infection With COVID-19

As a new infectious disease, COVID-19 is spread through the respiratory tract in most cases. Its source and pathological mechanism are not clear. The most common clinical feature is pulmonary infection. Also, a lot patients have gastrointestinal symptoms. Angiotensin-converting enzyme 2 (ACE2) is a functional cellular receptor for SARS-CoV-2, which is like SARS-CoV, a coronavirus associated with severe acute respiratory syndrome (SARS) outbreak in 2003. The tissues and cells expressing ACE2 are potential targets for SARS-CoV-2 infection, and the high expression of ACE2 in intestinal epithelial cells marks that SARS-CoV-2 may directly infect intestinal epithelial cells. Recent studies also suggest that SARS-CoV-2 existed and replicated in intestinal environment for a long time. The interaction between SARS-CoV-2 and RAS system leads to the decrease of local anti-inflammatory ability. The virus cycle leads to excessive imbalance of immune response and cytokine release. The downregulation of ACE2 after viral infection leads to gastrointestinal dysfunction. The above are the causes of gastrointestinal symptoms. Here, we reviewed the possible causes and mechanisms of gastrointestinal symptoms caused by COVID-19. Additionally, we discussed the influence of gastrointestinal symptoms on the prognosis of patients.

COVID-19-Associated acute respiratory distress syndrome (CARDS): Mechanistic insights on therapeutic intervention and emerging trends

AIMS

The novel Coronavirus disease 2019 (COVID-19) has caused great distress worldwide. Acute respiratory distress syndrome (ARDS) is well familiar but when it happens as part of COVID-19 it has discrete features which are unmanageable. Numerous pharmacological treatments have been evaluated in clinical trials to control the clinical effects of CARDS, but there is no assurance of their effectiveness.

MATERIALS AND METHODS

A systematic review of the literature of the Medline, Scopus, Bentham, PubMed, and EMBASE (Elsevier) databases was examined to understand the novel therapeutic approaches used in COVID-19-Associated Acute Respiratory Distress Syndrome and their outcomes.

KEY FINDINGS

Current therapeutic options may not be enough to manage COVID-19-associated ARDS complications in group of patients and therefore, the current review has discussed the pathophysiological mechanism of COVID-19-associated ARDS, potential pharmacological treatment and the emerging molecular drug targets.

SIGNIFICANCE

The rationale of this review is to talk about the pathophysiology of CARDS, potential pharmacological treatment and the emerging molecular drug targets. Currently accessible treatment focuses on modulating immune responses, rendering antiviral effects, anti-thrombosis or anti-coagulant effects. It is expected that considerable number of studies conducting globally may help to discover effective therapies to decrease mortality and morbidity occurring due to CARDS. Attention should be also given on molecular drug targets that possibly will help to develop efficient cure for COVID-19-associated ARDS.

Involvement of the ACE2/Ang-(1-7)/MasR Axis in Pulmonary Fibrosis: Implications for COVID-19

Pulmonary fibrosis is a chronic, fibrotic lung disease affecting 3 million people worldwide. The ACE2/Ang-(1–7)/MasR axis is of interest in pulmonary fibrosis due to evidence of its anti-fibrotic action. Current scientific evidence supports that inhibition of ACE2 causes enhanced fibrosis. ACE2 is also the primary receptor that facilitates the entry of SARS-CoV-2, the virus responsible for the current COVID-19 pandemic. COVID-19 is associated with a myriad of symptoms ranging from asymptomatic to severe pneumonia and acute respiratory distress syndrome (ARDS) leading to respiratory failure, mechanical ventilation, and often death. One of the potential complications in people who recover from COVID-19 is pulmonary fibrosis. Cigarette smoking is a risk factor for fibrotic lung diseases, including the idiopathic form of this disease (idiopathic pulmonary fibrosis), which has a prevalence of 41% to 83%. Cigarette smoke increases the expression of pulmonary ACE2 and is thought to alter susceptibility to COVID-19. Cannabis is another popular combustible product that shares some similarities with cigarette smoke, however, cannabis contains cannabinoids that may reduce inflammation and/or ACE2 levels. The role of cannabis smoke in the pathogenesis of pulmonary fibrosis remains unknown. This review aimed to characterize the ACE2-Ang-(1–7)-MasR Axis in the context of pulmonary fibrosis with an emphasis on risk factors, including the SARS-CoV-2 virus and exposure to environmental toxicants. In the context of the pandemic, there is a dire need for an understanding of pulmonary fibrotic events. More research is needed to understand the interplay between ACE2, pulmonary fibrosis, and susceptibility to coronavirus infection.

Alternative RAS in Various Hypoxic Conditions: From Myocardial Infarction to COVID-19

Alternative branches of the classical renin–angiotensin–aldosterone system (RAS) represent an important cascade in which angiotensin 2 (AngII) undergoes cleavage via the action of the angiotensin-converting enzyme 2 (ACE2) with subsequent production of Ang(1-7) and other related metabolites eliciting its effects via Mas receptor activation. Generally, this branch of the RAS system is described as its non-canonical alternative arm with counterbalancing actions to the classical RAS, conveying vasodilation, anti-inflammatory, anti-remodeling and anti-proliferative effects. The implication of this branch was proposed for many different diseases, ranging from acute cardiovascular conditions, through chronic respiratory diseases to cancer, nonetheless, hypoxia is one of the most prominent common factors discussed in conjugation with the changes in the activity of alternative RAS branches. The aim of this review is to bring complex insights into the mechanisms behind the various forms of hypoxic insults on the activity of alternative RAS branches based on the different duration of stimuli and causes (acute vs. intermittent vs. chronic), localization and tissue (heart vs. vessels vs. lungs) and clinical relevance of studied phenomenon (experimental vs. clinical condition). Moreover, we provide novel insights into the future strategies utilizing the alternative RAS as a diagnostic tool as well as a promising pharmacological target in serious hypoxia-associated cardiovascular and cardiopulmonary diseases.

Mefunidone Ameliorates Bleomycin-Induced Pulmonary Fibrosis in Mice

Idiopathic pulmonary fibrosis (IPF) is one of the most common and devastating interstitial lung diseases with poor prognosis. Currently, few effective drugs are available for IPF. Hence, we sought to explore the role of mefunidone (MFD), a newly synthesized drug developed by our team, in lung fibrosis. In this study, MFD was found to attenuate bleomycin (BLM) -induced lung fibrosis and inflammation in mice according to Ashcroft and alveolitis scoring. The protein contents and total cell counts in bronchoalveolar lavage fluids of BLM-treated mice were also lowered by MFD. Moreover, the elevation of TGF-β/Smad2 and phosphorylation of MAPK pathways was repressed by MFD. Additionally, MFD attenuated the swelling and vacuolization of mitochondria, lowered the ratio of apoptotic cells, restored the mitochondrial membrane potential, and reversed the expression of cleaved-caspase 3, Bcl-2 and Bax. Meanwhile, the level of epithelial marker, E-cadherin, was restored by MFD, while the levels of mesenchymal markers such as Snail and vimentin were down-regulated by MFD. Besides, MFD inhibited the expression of fibronectin and α-smooth muscle actin in TGF-β treated normal human lung fibroblasts. Thus, our findings suggested that MFD could ameliorate lung fibrosis, cell apoptosis and EMT potentially via suppression of TGF-β/Smad2 and MAPK pathways.

Renin angiotensin aldosterone system in pulmonary fibrosis: Pathogenesis to therapeutic possibilities

Pulmonary fibrosis is a devastating lung disease with multifactorial etiology characterized by alveolar injury, fibroblast proliferation and excessive deposition of extracellular matrix proteins, which progressively results in respiratory failure and death. Accumulating evidence from experimental and clinical studies supports a central role of the renin angiotensin aldosterone system (RAAS) in the pathogenesis and progression of idiopathic pulmonary fibrosis. Angiotensin II (Ang II), a key vasoactive peptide of the RAAS mediates pro-inflammatory and pro-fibrotic effects on the lungs, adversely affecting organ function. Recent years have witnessed seminal discoveries in the field of RAAS. Identification of new enzymes, peptides and receptors has led to the development of several novel concepts. Of particular interest is the establishment of a protective axis of the RAAS comprising of Angiotensin converting enzyme 2 (ACE2), Angiotensin-(1-7) [Ang-(1-7)], and the Mas receptor (the ACE2/Ang-(1-7)/Mas axis), and the discovery of a functional role for the Angiotensin type 2 (AT₂) receptor. Herein, we will review our current understanding of the role of RAAS in lung fibrogenesis, provide evidence on the anti-fibrotic actions of the newly recognized RAAS components (the ACE2/Ang-(1-7)/Mas axis and AT₂ receptor), discuss potential strategies and translational efforts to convert this new knowledge into effective therapeutics for PF.

Anlotinib Inhibits PFKFB3-Driven Glycolysis in Myofibroblasts to Reverse Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal disease in which the normal alveolar network is gradually replaced by fibrotic scars. Current evidence suggests that metabolic alterations correlate with myofibroblast activation in IPF. Anlotinib has been proposed to have antifibrotic effects, but the efficacy and mechanisms of anlotinib against lung fibrosis have not been systematically evaluated. The antifibrotic effects of anlotinib were evaluated in bleomycin-induced mouse models and transforming growth factor-beta 1 (TGF-β1)-stimulated lung fibroblasts. We measured lactate levels, 2-NBDG glucose uptake and the extracellular acidification rate (ECAR) to assess glycolysis in fibroblasts. RNA-protein coimmunoprecipitation (RIP) and polysome analyses were performed to investigate novel mechanisms of glycolytic reprogramming in pulmonary fibrosis. We found that anlotinib diminished myofibroblast activation and inhibited the augmentation of glycolysis. Moreover, we show that PCBP3 posttranscriptionally increases PFKFB3 expression by promoting its translation during myofibroblast activation, thus promoting glycolysis in myofibroblasts. Regarding mechanism, anlotinib exerts potent antifibrotic effects by downregulating PCBP3, reducing PFKFB3 translation and inhibiting glycolysis in myofibroblasts. Furthermore, we observed that anlotinib had preventative and therapeutic antifibrotic effects on bleomycin-induced pulmonary fibrosis. Therefore, we identify PCBP3 as a protein involved in the regulation of glycolysis reprogramming and lung fibrogenesis and propose it as a therapeutic target for pulmonary fibrosis. Our data suggest that anlotinib has antifibrotic effects on the lungs, and we provide a novel mechanism for this effect. Anlotinib may constitute a novel and potent candidate for the treatment of pulmonary fibrosis.

Apela inhibits systemic and renal inflammatory reactions in mice with type I cardiorenal syndrome

This study investigated the effect of apela on renal function and anti-inflammatory effect on whole body and kidney tissue in mice with type I cardiorenal syndrome (CRS). The murine type I CRS model was established and apela was subcutaneously infused for two weeks. Cardiac and renal functions were evaluated by echocardiography and blood biochemistry, respectively. The systemic and renal inflammatory responses were examined with molecular biological and histological methods. Human renal glomerular endothelial cells (RGECs) were used to evaluate the adhesion effect of monocytes in vitro. Compared to mice from the control group (CRS + vehicle), the plasma levels of N-terminal pro-brain natriuretic peptide, blood urea nitrogen and creatinine were significantly decreased, while the mean left ventricular ejection fraction was increased in apela-treated CRS mice at the 4th week. The expression of monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-α (TNF-α) in the circulation and kidney was decreased in apela-treated mice compared with control mice, and apela improved cardio-renal pathology in mice with type I CRS. Additionally, Apela significantly suppressed the expression of MCP-1, TNF-α, intercellular adhesion molecule-1 and vascular intercellular adhesion molecule-1 in RGECs induced by angiotensin II (Ang II), and inhibited the promoting effect of Ang II on the adhesion of THP-1 cells to RGECs. Western blot results showed that the expression of phosphorylated nuclear factor kappa B (phospho-NFκB) in CRS mice was increased, but the expression of phospho-NFκB was down-regulated after apela treatment. Furthermore, apela significantly inhibited the Ang II-mediated increase in phospho-NFκB expression in RGECs in vitro, but the administration of an apelin peptide jejunum receptor (APJ) inhibitor blocked the inhibitory effect of apela. This study revealed that apela improves cardiorenal function and reduces systemic and renal inflammatory response in type I CRS mice and the apela/APJ system may alleviate renal inflammatory responses by inhibiting the NFκB signalling pathway.

Macrophage exosomes transfer angiotensin II type 1 receptor to lung fibroblasts mediating bleomycin-induced pulmonary fibrosis

BACKGROUND

Macrophages are involved in the pathogenesis of idiopathic pulmonary fibrosis, partially by activating lung fibroblasts. However, how macrophages communicate with lung fibroblasts is largely unexplored. Exosomes can mediate intercellular communication, whereas its role in lung fibrogenesis is unclear. Here we aim to investigate whether exosomes can mediate the crosstalk between macrophages and lung fibroblasts and subsequently induce fibrosis.

METHODS

In vivo, bleomycin (BLM)-induced lung fibrosis model was established and macrophages infiltration was examined. The effects of GW4869, an exosomes inhibitor, on lung fibrosis were assessed. Moreover, macrophage exosomes were injected into mice to observe its pro-fibrotic effects. In vitro, exosomes derived from angiotensin II (Ang II)-stimulated macrophages were collected. Then, lung fibroblasts were treated with the exosomes. Twenty-four hours later, protein levels of α-collagen I, angiotensin II type 1 receptor (AT1R), transforming growth factor-β (TGF-β), and phospho-Smad2/3 (p-Smad2/3) in lung fibroblasts were examined. The Student's t test or analysis of variance were used for statistical analysis.

RESULTS

In vivo, BLM-treated mice showed enhanced infiltration of macrophages, increased fibrotic alterations, and higher levels of Ang II and AT1R. GW4869 attenuated BLM-induced pulmonary fibrosis. Mice with exosomes injection showed fibrotic features with higher levels of Ang II and AT1R, which was reversed by irbesartan. In vitro, we found that macrophages secreted a great number of exosomes. The exosomes were taken by fibroblasts and resulted in higher levels of AT1R (0.22 ± 0.02 vs. 0.07 ± 0.02, t = 8.66, P = 0.001), TGF-β (0.54 ± 0.05 vs. 0.09 ± 0.06, t = 10.00, P < 0.001), p-Smad2/3 (0.58 ± 0.06 vs. 0.07 ± 0.03, t = 12.86, P < 0.001) and α-collagen I (0.27 ± 0.02 vs. 0.16 ± 0.01, t = 7.01, P = 0.002), and increased Ang II secretion (62.27 ± 7.32 vs. 9.56 ± 1.68, t = 12.16, P < 0.001). Interestingly, Ang II increased the number of macrophage exosomes, and the protein levels of Alix (1.45 ± 0.15 vs. 1.00 ± 0.10, t = 4.32, P = 0.012), AT1R (4.05 ± 0.64 vs. 1.00 ± 0.09, t = 8.17, P = 0.001), and glyceraldehyde-3-phosphate dehydrogenase (2.13 ± 0.36 vs. 1.00 ± 0.10, t = 5.28, P = 0.006) were increased in exosomes secreted by the same number of macrophages, indicating a positive loop between Ang II and exosomes production.

CONCLUSIONS

Exosomes mediate intercellular communication between macrophages and fibroblasts plays an important role in BLM-induced pulmonary fibrosis.

Coronavirus disease 2019 (COVID-19): Biophysical and biochemical aspects of SARS-CoV-2 and general characteristics

The coronavirus disease (COVID-19) arises from the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) which is an enveloped RNA virus. COVID-19 has rapidly spread throughout the world by infecting more than 143 million people and causing 3.04 million deaths worldwide by 22 April 2021, confirmed by the World Health Organization. It caused great concern and pandemic all over the world, therewithal there has not been found any specific and efficient treatment yet. In the current review, we aimed to define the biophysical and biochemical aspects of SARS-CoV-2, including renin-angiotensin-system, cytokine storms, receptor binding, protein structural and functional features, molecular interactions, and conformational changes that take place during viral attachment and entering into human cells. It was also aimed to highlight the general hallmarks of COVID-19, including treatment strategies, diagnosis and even prevention. Thus, this review will serve as an updated comprehensive body of information and discussion on COVID-19 and will help the molecular scientists, biophysicists, clinicians, as well as medical engineers. Thereby, further understanding of COVID-19 will provide novel insights and advances in development of therapeutic potentials and vaccine alternatives as well as in detection of specific targets for diagnosis.

The secret identities of TMPRSS2: Fertility factor, virus trafficker, inflammation moderator, prostate protector and tumor suppressor

The human TMPRSS2 gene is pathogenetically implicated in both coronaviral lung infection and prostate cancer, suggesting its potential as a drug target in both contexts. SARS-COV-2 spike polypeptides are primed by the host transmembrane TMPRSS2 protease, triggering virus fusion with epithelial cell membranes followed by an endocytotic internalisation process that bypasses normal endosomal activation of cathepsin-mediated innate immunity; viral co-opting of TMPRSS2 thus favors microbial survivability by attenuating host inflammatory responses. In contrast, most early hormone-dependent prostate cancers express TMPRSS2:ERG fusion genes arising from deletions that eliminate the TMPRSS2 coding region while juxtaposing its androgen-inducible promoter and the open reading frame of ERG, upregulating pro-inflammatory ERG while functionally disabling TMPRSS2. Moreover, inflammatory oxidative DNA damage selects for TMPRSS2:ERG-fused cancers, whereas patients treated with antiinflammatory drugs develop fewer of these fusion-dependent tumors. These findings imply that TMPRSS2 protects the prostate by enabling endosomal bypass of pathogens which could otherwise trigger inflammation-induced DNA damage that predisposes to TMPRSS2:ERG fusions. Hence, the high oncogenic selectability of TMPRSS2:ERG fusions may reflect a unique pro-inflammatory synergy between androgenic ERG gain-of-function and fusogenic TMPRSS2 loss-of-function, cautioning against the use of TMPRSS2-inhibitory drugs to prevent or treat early prostate cancer.

Classical and Counter-Regulatory Renin-Angiotensin System: Potential Key Roles in COVID-19 Pathophysiology

In the current COVID-19 pandemic, severe acute respiratory syndrome coronavirus 2 uses angiotensin-converting enzyme-2 (ACE-2) receptors for cell entry, leading to ACE-2 dysfunction and downregulation, which disturb the balance between the classical and counter-regulatory renin-angiotensin system (RAS) in favor of the classical RAS. RAS dysregulation is one of the major characteristics of several cardiovascular diseases; thus, adjustment of this system is the main therapeutic target. RAS inhibitors-particularly angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II type 1 receptor blockers (ARBs)-are commonly used for treatment of hypertension and cardiovascular disease. Patients with cardiovascular diseases are the group most commonly seen among those with COVID-19 comorbidity. At the beginning of this pandemic, a dilemma occurred regarding the use of ACEIs and ARBs, potentially aggravating cardiovascular and pulmonary dysfunction in COVID-19 patients. Urgent clinical trials from different countries and hospitals reported that there is no association between RAS inhibitor treatment and COVID-19 infection or comorbidity complication. Nevertheless, the disturbance of the RAS that is associated with COVID-19 infection and the potential treatment targeting this area have yet to be resolved. In this review, the link between the dysregulation of classical RAS and counter-regulatory RAS activities in COVID-19 patients with cardiovascular metabolic diseases is investigated. In addition, the latest findings based on ACEI and ARB administration and ACE-2 availability in relation to COVID-19, which may provide a better understanding of the RAS contribution to COVID-19 pathology, are discussed, as they are of the utmost importance amid the current pandemic.

Lock, Stock and Barrel: Role of Renin-Angiotensin-Aldosterone System in Coronavirus Disease 2019

Since the end of 2019, the medical-scientific community has been facing a terrible pandemic caused by a new airborne viral agent known as SARS-CoV2. Already in the early stages of the pandemic, following the discovery that the virus uses the ACE2 cell receptor as a molecular target to infect the cells of our body, it was hypothesized that the renin-angiotensin-aldosterone system was involved in the pathogenesis of the disease. Since then, numerous studies have been published on the subject, but the exact role of the renin-angiotensin-aldosterone system in the pathogenesis of COVID-19 is still a matter of debate. RAAS represents an important protagonist in the pathogenesis of COVID-19, providing the virus with the receptor of entry into host cells and determining its organotropism. Furthermore, following infection, the virus is able to cause an increase in plasma ACE2 activity, compromising the normal function of the RAAS. This dysfunction could contribute to the establishment of the thrombo-inflammatory state characteristic of severe forms of COVID-19. Drugs targeting RAAS represent promising therapeutic options for COVID-19 sufferers.

Broadening COVID-19 Interventions to Drug Innovation: Neprilysin Pathway as a Friend, Foe, or Promising Molecular Target?

The coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus is anticipated to transition to an endemic state as vaccines are providing relief in some, but not all, countries. Drug discovery for COVID-19 can offer another tool in the fight against the pandemic. Additionally, COVID-19 impacts multiple organs that call for a systems medicine approach to planetary health and therapeutics innovation. In this context, innovation for drugs that prevent and treat COVID-19 is timely and much needed. As the virus variants emerge under different ecological conditions and contexts in the long haul, a broad array of vaccine and drug options will be necessary. This expert review article argues for a need to expand the COVID-19 interventions, including and beyond vaccines, to stimulate discovery and development of novel medicines against SARS-CoV-2 infection. The Renin-Angiotensin-Aldosterone System (RAAS) is known to play a major role in SARS-CoV-2 infection. Neprilysin (NEP) and angiotensin-converting enzyme (ACE) have emerged as the pharmaceutical targets of interest in the search for therapeutic interventions against COVID-19. While the NEP/ACE inhibitors offer promise for repurposing against COVID-19, they may display a multitude of effects in different organ systems, some beneficial, and others adverse, in modulating the inflammation responses in the course of COVID-19. This expert review offers an analysis and discussion to deepen our present understanding of the pathophysiological function of neprilysin in multiple organs, and the possible effects of NEP inhibitor-induced inflammatory responses in COVID-19-infected patients.

Influence of Seasonal Vitamin D Changes on Clinical Manifestations of Rheumatoid Arthritis and Systemic Sclerosis

Vitamin D [1,25(OH)2D-calcitriol] is basically a steroid hormone with pleiotropic biologic effects, and its impact on the regulation of immune system may influence several clinical conditions. Calcidiol (25OHD), as precursor of calcitriol, derives, for the most part (80%), from cutaneous cholesterol (7-dehydrocholesterol) under the action of UV-B (sunlight). Consequently, serum concentrations fluctuate during the year following the circannual rhythm of sun exposition. We will update about the available evidence regarding the complex influence of seasonal vitamin D changes on two different chronic connective tissue diseases, namely rheumatoid arthritis (RA) and systemic sclerosis (SSc). Notably, RA is an emblematic model of autoimmune disease with prevalent joint inflammatory features, while SSc is mainly an autoimmune progressive pro-fibrotic disease. However, in both conditions, low serum concentrations of 25OHD are involved in the pathogenesis of the diseases, and emerging data report their impact on clinical manifestations.