Pathways of hepatic and renal damage through non-classical activation of the renin-angiotensin system in chronic liver disease

Possible role of LCZ696 in atherosclerosis: new inroads and perspective

LCZ696 blocks both angiotensin receptor type 1 (ATR1) and neprilysin (NEP), which are intricate in the degradation of natriuretic peptides (NPs) and other endogenous peptides. It has been shown NEP inhibitors and LCZ696 could be effectively in the management of atherosclerosis (AS). However, the underlying mechanism of LCZ696 in AS is needed to be clarified entirely. Hence, this review is directed to reconnoiter the mechanistic role of LCZ696 in AS. The anti-inflammatory role of LCZ696 is related to the inhibition of transforming growth factor beta (TGF-β)-activated kinase 1 (TAK) and nod-like receptor pyrin 3 receptor (NLRP3) inflammasome. Moreover, LCZ696, via inhibition of pro-inflammatory cytokines, oxidative stress, apoptosis and endothelial dysfunction can attenuate the development and progression of AS. In conclusion, LCZ696 could be effective in the management of AS through modulation of inflammatory and oxidative signaling. Preclinical and clinical studies are recommended in this regard.

The Renin-Angiotensin System in Liver Disease

The renin-angiotensin system (RAS) is a complex homeostatic entity with multiorgan systemic and local effects. Traditionally, RAS works in conjunction with the kidney to control effective arterial circulation, systemic vascular resistance, and electrolyte balance. However, chronic hepatic injury and resulting splanchnic dilation may disrupt this delicate balance. The role of RAS in liver disease, however, is even more extensive, modulating hepatic fibrosis and portal hypertension. Recognition of an alternative RAS pathway in the past few decades has changed our understanding of RAS in liver disease, and the concept of opposing vs. "rebalanced" forces is an ongoing focus of research. Whether RAS inhibition is beneficial in patients with chronic liver disease appears to be context-dependent, but further study is needed to optimize clinical management and reduce organ-specific morbidity and mortality. This review presents the current understanding of RAS in liver disease, acknowledges areas of uncertainty, and describes potential areas of future investigation.

Can Plasma Volume Determination in Cirrhosis Be Replaced by an Algorithm Using Body Weight and Hematocrit?

BACKGROUND

Patients with cirrhosis often develop hyperdynamic circulation with increased cardiac output, heart rate, and redistribution of the circulating volume with expanded plasma volume (PV). PV determination is part of the evaluation of patients with cirrhosis, but gold-standard methods are invasive, expensive, and time-consuming. Therefore, other estimations of PV would be preferable, and the aim of this study was therefore to study if PV, as assessed by a simplified algorithm based on hematocrit and weight, can replace the gold-standard method.

METHODS

We included 328 patients with cirrhosis who had their PV assessed by the indicator dilution technique as the gold-standard method (PVI-125). Actual PV was estimated as PVa = (1 - hematocrit)·(a + (b·body weight)). Ideal PV was estimated as PVi = c · body weight, where a, b, and c are constants.

RESULTS

PVI-125, PVa, and PVi were 3.99 ± 1.01, 3.09 ± 0.54, and 3.01 ± 0.65 (Mean ± SD), respectively. Although PVI-125 correlated significantly with PVa (r = 0.72, p < 0.001), a Bland-Altman plot revealed wide limits of confidence.

CONCLUSIONS

The use of simplified algorithms does not sufficiently estimate PV and cannot replace the indicator dilution technique.

The classical and non-classical axes of renin-angiotensin system in Parkinson disease: The bright and dark side of the moon

Parkinson disease (PD) is a common brain neurodegenerative disease due to progressive degeneration of the dopaminergic neurons in the substantia nigra pars compacta (SNpc). Of note, the cardio-metabolic disorders such as hypertension are adversely affect PD neuropathology through exaggeration of renin-angiotensin system (RAS). The RAS affects the stability of dopaminergic neurons in the SNpc, and exaggeration of angiotensin II (AngII) is implicated in the development and progression of PD. RAS has two axes classical including angiotensin converting enzyme (ACE)/AngII/AT1R, and the non-classical axis which include ACE2/Ang1-7/Mas receptor, AngIII, AngIV, AT2R, and AT4R. It has been shown that brain RAS is differs from that of systemic RAS that produce specific neuronal effects. As well, there is an association between brain RAS and PD. Therefore, this review aims to revise from published articles the role of brain RAS in the pathogenesis of PD focusing on the non-classical pathway, and how targeting of this axis can modulate PD neuropathology.

Partial Replacement of NaCl with KCl in Cooked Meat Could Reduce the Liver Damage Through Renin-Angiotensin System in Mice

SCOPE

Dietary salt (sodium chloride, NaCl) is necessary for processed meat products, but intake of a high-sodium diet carries serious health risks. Considerable studies indicate that the partial substitution of NaCl with potassium chloride (KCl) can produce sodium-reduced cooked meat. However, most studies of sodium-reduced cooked meat focus on the production process in vitro, and the effect of cooked meat on health has not been well clarified in vivo.

METHODS AND RESULTS

This study finds that compared to the high-sodium group (HS), serum renin, angiotensin-converting enzyme (ACE), angiotensin (Ang) II, and the levels of some indicators of dyslipidemia are decreased in the reduced salt by partial substitution of NaCl with KCl group (RS + K). Furthermore, RS + K increases the antioxidation abilities, inhibits the renin-angiotensin system (RAS) through ACE/Ang II/Ang II type 1 receptor axis pathway, reduces synthesis of triglyceride and cholesterol and protein expressions of inflammatory factors interleukin-17A and nuclear factor-kappa B in the liver.

CONCLUSION

Partial substitution of NaCl with KCl in cooked meat can be a feasible approach for improving the health benefits and developing novel functional meat products for nutritional health interventions.

Angiotensin-converting enzyme inhibitory peptide IVGFPAYGH protects against liver injury in mice fed a high‑sodium diet by inhibiting the RAS and remodeling gut microbial communities

Consuming a high‑sodium diet carries serious health risks and significantly influences the activation state of the renin-angiotensin system (RAS). This study evaluates the protective effect of angiotensin-converting enzyme (ACE) inhibitory peptide IVGFPAYGH on a high‑sodium diet-induced liver injury. IVGFPAYGH supplementation increased the activities of liver antioxidase and decreased the levels of liver inflammatory factor in mice fed a high‑sodium diet (8 % NaCl). IVGFPAYGH supplementation also reduced liver fatty acid synthesis and promoted fatty acid oxidation, increased the expression of low-density lipoprotein receptor, and improved liver dyslipidemia. Furthermore, IVGFPAYGH supplementation inhibited the activation of the liver RAS via inhibiting ACE activity and reducing angiotensin II levels in mice fed a high‑sodium diet. Moreover, IVGFPAYGH supplementation could alter the gut microbiota composition toward a normal gut microbiota composition and increase the abundance of the Lactobacillus genus. IVGFPAYGH supplementation also increased the expression levels of small intestinal tight junction protein and cecum short-chain fatty acids. Thus, IVGFPAYGH supplementation may maintain intestinal homeostasis and improve high‑sodium diet-induced liver injury by altering the gut microbiota composition and inhibiting the RAS. IVGFPAYGH is a promising functional ingredient for protecting liver damage caused by a high‑sodium diet.

Pseudohypoadrenalism, a subclinical cortisol metabolism disorder in hyperuricemia

Background

Hyperuricemia is a known risk factor of lipid metabolism disorder. However, the mechanisms have not been fully understood.

Methods

The serum samples from hyperuricemia subjects were used to analyze the correlation between serum uric acid and clinical characteristics. Hyperuricemia mice induced by potassium oxonate (PO) and adenine were used to explore glucocorticoid metabolism.

Results

In hyperuricemia patients, the levels of serum uric acid were positively correlated with the levels of γ-glutamyltransferase, associated with a cortisol metabolism disorder. In hyperuricemia state, the adrenal glands failed to respond to adrenocorticotropic hormone properly, leading to low cortisol, but not corticosterone production, and decreased mRNA levels of aldosterone synthase, 11β-hydroxylase, and 3β-hydroxysteroid dehydrogenase 1, three key enzymes for cortisol synthesis. The expression of both hepatic 5α-reductase and renal 11β-hydroxysteroid dehydrogenase 2 was significantly reduced, which led to low cortisol clearance. We denominated this cortisol metabolism disorder in hyperuricemia as pseudohypoadrenalism (PHAL).

Conclusion

PHAL increased exposure to the bioavailable cortisol in the liver, leading to local amplification of the biological action of corticosteroids. Unregulated biosynthesis pathway of bile acid expanded bile acid pool, and further aggravated cholestatic liver injury.

Effects of renin-angiotensin inhibitors on renal function and the clinical course in patients with decompensated cirrhosis

Patients with decompensated cirrhosis are at risk of developing acute kidney injury (AKI). Studies have suggested that inhibition of the Renin-Angiotensin System (RAS) has certain nephro- and hepatoprotective effects in patients with compensated liver disease. This study aimed to investigate the clinical impact of RAS-Inhibitors in individuals with decompensated liver cirrhosis. Overall, 1181 consecutive hospitalized patients with ascites that underwent paracentesis were considered for this retrospective study. In total, 667 patients with decompensated cirrhosis fulfilled the inclusion criteria and were finally analyzed. RAS-Inhibitor intake was documented in 41 patients (7%). First, 28-day incidences of AKI and grade III AKI of all patients with RAS-Inhibitors were compared to those without intake. Afterwards, propensity score matching was conducted in a 3:1 manner. Here, incidence of further renal endpoints such as need of hemodialysis were analyzed in detail. In the unmatched setting, intake of RAS-Inhibitors was not associated with an increased 28 day-incidence of AKI (P = 0.76) or LTx-free survival (P = 0.60). However, 28 day-incidence of grade III AKI was significantly lower in patients with RAS-Inhibitor intake (P < 0.001). In the matched setting, 28 day-incidence of AKI did not differ (P = 0.81), while grade III AKI was significantly less frequent in the RAS-Inhibitor group (P < 0.001). Need for hemodialysis was also significantly lower in patients with RAS-Inhibitors (P = 0.03) and LTx-free survival was comparable between both groups (P = 0.52). Thus, this study suggests that intake of RAS-Inhibitors is associated with decreased incidences of grade III AKI and need of hemodialysis in patients with decompensated liver disease.

Advances in understanding and treating diabetic kidney disease: focus on tubulointerstitial inflammation mechanisms

Diabetic kidney disease (DKD) is a serious complication of diabetes that can lead to end-stage kidney disease. Despite its significant impact, most research has concentrated on the glomerulus, with little attention paid to the tubulointerstitial region, which accounts for the majority of the kidney volume. DKD's tubulointerstitial lesions are characterized by inflammation, fibrosis, and loss of kidney function, and recent studies indicate that these lesions may occur earlier than glomerular lesions. Evidence has shown that inflammatory mechanisms in the tubulointerstitium play a critical role in the development and progression of these lesions. Apart from the renin-angiotensin-aldosterone blockade, Sodium-Glucose Linked Transporter-2(SGLT-2) inhibitors and new types of mineralocorticoid receptor antagonists have emerged as effective ways to treat DKD. Moreover, researchers have proposed potential targeted therapies, such as inhibiting pro-inflammatory cytokines and modulating T cells and macrophages, among others. These therapies have demonstrated promising results in preclinical studies and clinical trials, suggesting their potential to treat DKD-induced tubulointerstitial lesions effectively. Understanding the immune-inflammatory mechanisms underlying DKD-induced tubulointerstitial lesions and developing targeted therapies could significantly improve the treatment and management of DKD. This review summarizes the latest advances in this field, highlighting the importance of focusing on tubulointerstitial inflammation mechanisms to improve DKD outcomes.

An impaired pituitary-adrenal signalling axis in stable cirrhosis is linked to worse prognosis

Background & Aims

Inadequate adrenal function has been described in patients with cirrhosis. We investigated (i) the pituitary-adrenal axis at different clinical stages and (ii) the clinical impact of decreased serum cortisol levels in stable patients with advanced chronic liver disease (ACLD).

Methods

We included 137 outpatients with ACLD undergoing hepatic venous pressure gradient (HVPG) measurement in the prospective VICIS study (NCT03267615). Patients were stratified into six clinical stages: S0: subclinical portal hypertension (PH) (HVPG 6-9 mmHg), S1: clinically significant PH (HVPG ≥10 mmHg) without varices, S2: presence of varices, S3: previous variceal bleeding, S4: previous non-bleeding decompensation, and S5: further decompensation.

Results

Fifty-one patients had compensated ACLD (S0: n = 13; S1: n = 12; S2: n = 26), whereas 86 patients had decompensated ACLD (S3: n = 7; S4: n = 46; S5: n = 33). Serum total cortisol (t-Cort) showed a strong correlation with estimated serum free cortisol (f-Cort; Spearman's ρ: 0.889). With progressive clinical stage, median ACTH levels (from S0: 44.0 pg/ml to S5: 20.0 pg/ml; p = 0.006), t-Cort (from S0: 13.9 μg/dl to S5: 9.2 μg/dl; p = 0.091), and cortisol binding globulin (from S0: 49.3 μg/ml to S5: 38.9 μg/ml; p <0.001) decreased, whereas f-Cort (p = 0.474) remained unchanged. Lower t-Cort levels independently predicted bacterial infections (asHR: 1.11; 95% CI: 1.04-1.19; p = 0.002), further decompensation (asHR: 1.08; 95% CI: 1.02-1.12; p = 0.008), acute-on-chronic liver failure (ACLF; asHR: 1.11; 95% CI: 1.04-1.19; p = 0.002), and liver-related death (asHR: 1.09; 95% CI: 1.01-1.18; p = 0.045).

Conclusions

The pituitary-ACTH-adrenal-cortisol axis is progressively suppressed with increasing severity of cirrhosis. Lower t-Cort is an independent risk factor for bacterial infections, further decompensation of ACLF, and liver-related mortality-even in stable outpatients with cirrhosis.

Clinical trial number

Vienna Cirrhosis Study (VICIS; NCT: NCT03267615).

Impact and Implications

In a cohort of stable outpatients, we observed progressive suppression of the pituitary-adrenal axis with increasing clinical stage of advanced chronic liver disease (ACLD). Increased levels of bile acids and systemic inflammation (assessed by interleukin-6 levels) could be involved in this suppression. Serum total cortisol (t-Cort) was strongly correlated with serum free cortisol (f-Cort) and lower t-Cort levels were independently associated with a higher risk of adverse clinical outcomes, including bacterial infections, further decompensation, acute-on-chronic liver failure, and liver-related death.

New Viral Diseases and New Possible Remedies by Means of the Pharmacology of the Renin-Angiotensin System

All strains of SARS-CoV-2, as well as previously described SARS-CoV and MERS-CoV, bind to ACE2, the cell membrane receptor of β-coronaviruses. Monocarboxypeptidase ACE2 activity stops upon viral entry into cells, leading to inadequate tissue production of angiotensin 1-7 (Ang1-7). Acute lung injury due to the human respiratory syncytial virus (hRSV) or avian influenza A H7N9 and H5N1 viruses is also characterized by significant downregulation of lung ACE2 and increased systemic levels of angiotensin II (Ang II). Restoration of Ang1-7 anti-inflammatory, antifibrotic, vasodilating, and natriuretic properties was attempted at least in some COVID-19 patients through i.v. infusion of recombinant human ACE2 or intranasal administration of the modified ACE2 protein, with inconsistent clinical results. Conversely, use of ACE inhibitors (ACEis), which increase ACE2 cell expression, seemed to improve the prognosis of hypertensive patients with COVID-19. To restore Ang1-7 tissue levels in all these viral diseases and avoid the untoward effects frequently seen with ACE2 systemic administration, a different strategy may be hypothesized. Experimentally, when metallopeptidase inhibitors block ACE2, neprilysin (NEP), highly expressed in higher and lower airways, starts cleaving angiotensin I (Ang I) into Ang1-7. We suggest a discerning use of ACEis in normohypertensive patients with β-coronavirus disease as well as in atypical pneumonia caused by avian influenza viruses or hRSV to block the main ACE-dependent effects: Ang II synthesis and Ang1-7 degradation into angiotensin 1-5. At the same time, i.v.-infused Ang I, which is not hypertensive provided ACE is inhibited, may become the primary substrate for local Ang1-7 synthesis via ubiquitous NEP; i.e., NEP could replace inadequate ACE2 function if Ang I was freely available. Moreover, inhibitors of chymase, a serine endopeptidase responsible for 80% of Ang II-forming activity in tissues and vessel walls, could protect patients with atypical pneumonia from Ang II-mediated microvascular damage without reducing arterial blood pressure.

Nonalcoholic Fatty Liver Disease and Chronic Kidney Disease Cross Talk

Nonalcoholic fatty liver disease is a multisystem condition with effects beyond the liver. The identification of chronic kidney disease as an independent mediator of nonalcoholic fatty liver disease or associated entity with shared cardiometabolic risk factors remains controversial and continues to draw scientific interest. With increasing prevalence of nonalcoholic fatty liver disease and lack of Food and Drug Administration approved therapies, these shared cardiometabolic risk factors have drawn significant attention. In this article, we review shared pathophysiological mechanisms between nonalcoholic fatty liver disease and chronic kidney disease along with current treatment strategies that might be useful for both disease processes.

Cathepsins in the extracellular space: Focusing on non-lysosomal proteolytic functions with clinical implications

Cathepsins can be found in the extracellular space, cytoplasm, and nucleus. It was initially suspected that the primary physiological function of the cathepsins was to break down intracellular protein, and that they also had a role in pathological processes including inflammation and apoptosis. However, the many actions of cathepsins outside the cell and their complicated biological impacts have garnered much interest. Cathepsins play significant roles in a number of illnesses by regulating parenchymal cell proliferation, cell migration, viral invasion, inflammation, and immunological responses through extracellular matrix remodeling, signaling disruption, leukocyte recruitment, and cell adhesion. In this review, we outline the physiological roles of cathepsins in the extracellular space, the crucial pathological functions performed by cathepsins in illnesses, and the recent breakthroughs in the detection and therapy of specific inhibitors and fluorescent probes in associated dysfunction.

Renin-angiotensin-aldosterone pathway modulators in chronic kidney disease: A comparative review

Chronic kidney disease presents a health challenge that has a complex underlying pathophysiology, both acquired and inherited. The pharmacotherapeutic treatment options available today lower the progression of the disease and improve the quality of life but cannot completely cure it. This poses a challenge to the healthcare provider to choose, from the available options, the best way to manage the disease as per the presentation of the patient. As of now, the recommended first line of treatment to control the blood pressure in chronic kidney disease is the administration of renin-angiotensin-aldosterone system modulators. These are represented mainly by the direct renin inhibitor, angiotensin-converting enzyme inhibitors, and angiotensin II receptor blockers. These modulators are varied in their structure and mechanisms of action, hence showing varying treatment outcomes. The choice of administration of these modulators is determined by the presentation and the co-morbidities of the patient, the availability and affordability of the treatment option, and the expertise of the healthcare provider. A direct head-to-head comparison between these significant renin-angiotensin-aldosterone system modulators is lacking, which can benefit healthcare providers and researchers. In this review, a comparison has been drawn between the direct renin inhibitor (aliskiren), angiotensin-converting enzyme inhibitors, and angiotensin II receptor blockers. This can be of significance for healthcare providers and researchers to find the particular loci of interest, either in structure or mechanism, and to intervene as per the case presentation to obtain the best possible treatment option.

The systemic and hepatic alternative renin-angiotensin system is activated in liver cirrhosis, linked to endothelial dysfunction and inflammation

We aimed to assess the systemic and hepatic renin-angiotensin-system (RAS) fingerprint in advanced chronic liver disease (ACLD). This prospective study included 13 compensated (cACLD) and 12 decompensated ACLD (dACLD) patients undergoing hepatic venous pressure gradient (HVPG) measurement. Plasma components (all patients) and liver-local enzymes (n = 5) of the RAS were analyzed using liquid chromatography-tandem mass spectrometry. Patients with dACLD had significantly higher angiotensin (Ang) I, Ang II and aldosterone plasma levels. Ang 1-7, a major mediator of the alternative RAS, was almost exclusively detectable in dACLD (n = 12/13; vs. n = 1/13 in cACLD). Also, dACLD patients had higher Ang 1-5 (33.5 pmol/L versus cACLD: 6.6 pmol/L, p < 0.001) and numerically higher Ang III and Ang IV levels. Ang 1-7 correlated with HVPG (ρ = 0.655; p < 0.001), von Willebrand Factor (ρ = 0.681; p < 0.001), MELD (ρ = 0.593; p = 0.002) and interleukin-6 (ρ = 0.418; p = 0.047). Considerable activity of ACE, chymase, ACE2, and neprilysin was detectable in all liver biopsies, with highest chymase and ACE2 activity in cACLD patients. While liver-local classical and alternative RAS activity was already observed in cACLD, systemic activation of alternative RAS components occurred only in dACLD. Increased Ang 1-7 was linked to severe liver disease, portal hypertension, endothelial dysfunction and inflammation.

Integrated spatially resolved metabolomics and network toxicology to investigate the hepatotoxicity mechanisms of component D of Polygonum multiflorum Thunb

ETHNOPHARMACOLOGICAL RELEVANCE

The liver toxicity of Reynoutria multiflora (Thunb.) Moldenke. (Polygonaceae) (Polygonum multiflorum Thunb, PM) has always attracted much attention, but the related toxicity materials and mechanisms have not been elucidated due to multi-component and multi-target characteristics. In previous hepatotoxicity screening, different components of PM were first evaluated and the hepatotoxicity of component D [95% ethanol (EtOH) elution] in a 70% EtOH extract of PM (PM-D) showed the highest hepatotoxicity. Furthermore, the main components of PM-D were identified and their hepatotoxicity was evaluated based on a zebrafish embryo model. However, the hepatotoxicity mechanism of PM-D is unknown.

AIM OF THE STUDY

This work is to explore the hepatotoxicity mechanisms of PM-D by integrating network toxicology and spatially resolved metabolomics strategy.

MATERIALS AND METHODS

A hepatotoxicity interaction network of PM-D was constructed based on toxicity target prediction for eight key toxic ingredients and a hepatotoxicity target collection. Then the key signaling pathways were enriched, and molecular docking verification was implemented to evaluate the ability of toxic ingredients to bind to the core targets. The pathological changes of liver tissues and serum biochemical assays of mice were used to evaluate the liver injury effect of mice with oral administration of PM-D. Furthermore, spatially resolved metabolomics was used to visualize significant differences in metabolic profiles in mice after drug administration, to screen hepatotoxicity-related biomarkers and analyze metabolic pathways.

RESULTS

The contents of four key toxic compounds in PM-D were detected. Network toxicology identified 30 potential targets of liver toxicity of PM-D. GO and KEGG enrichment analyses indicated that the hepatotoxicity of PM-D involved multiple biological activities, including cellular response to endogenous stimulus, organonitrogen compound metabolic process, regulation of the apoptotic process, regulation of kinase, regulation of reactive oxygen species metabolic process and signaling pathways including PI3K-Akt, AMPK, MAPK, mTOR, Ras and HIF-1. The molecular docking confirmed the high binding activity of 8 key toxic ingredients with 10 core targets, including mTOR, PIK3CA, AKT1, and EGFR. The high distribution of metabolites of PM-D in the liver of administrated mice was recognized by mass spectrometry imaging. Spatially resolved metabolomics results revealed significant changes in metabolic profiles after PM-D administration, and metabolites such as taurine, taurocholic acid, adenosine, and acyl-carnitines were associated with PM-D-induced liver injury. Enrichment analyses of metabolic pathways revealed tht linolenic acid and linoleic acid metabolism, carnitine synthesis, oxidation of branched-chain fatty acids, and six other metabolic pathways were significantly changed. Comprehensive analysis revealed that the hepatotoxicity caused by PM-D was closely related to cholestasis, mitochondrial damage, oxidative stress and energy metabolism, and lipid metabolism disorders.

CONCLUSIONS

In this study, the hepatotoxicity mechanisms of PM-D were comprehensively identified through an integrated spatially resolved metabolomics and network toxicology strategy, providing a theoretical foundation for the toxicity mechanisms of PM and its safe clinical application.

Activatable self-assembled organic nanotheranostics: Aspartyl aminopeptidase triggered NIR fluorescence imaging-guided photothermal/photodynamic synergistic therapy

Phototherapy has developed as a powerful method for remedial modalities. The conventional photosensitizers are "always on" state and lack tumor targeting, which contributed to poor therapeutic effect and high toxicity. Therefore, we developed an aspartyl aminopeptidase (DNPEP) activated self-assembled organic nanoparticles (NRh-Asp NPs) with sensitive external irradiation-induced photothermal therapy and photodynamic therapy (PTT/PDT). NRh-Asp NPs can be activated to NRh-NH₂ NPs by DNPEP, demonstrating strong near-infrared (NIR) fluorescence, and efficiently generating heat and singlet oxygen under the near-infrared laser. NRh-Asp NPs was successfully used for visualizing DNPEP in vitro and in vivo in NIR region, and demonstrated good synergistic anti-cancer efficacy of PDT and PTT. These results suggest that DNPEP-mediated NRh-Asp NPs are promising candidates for image-guided phototherapeutic of tumor.

Angiotensin-converting enzyme 2 improves hepatic insulin resistance by regulating GABAergic signaling in the liver

The angiotensin-converting enzyme 2 (ACE2)/angiotensin 1-7/MAS axis and the gamma-aminobutyric acid (GABA)ergic signaling system have both been shown to have the dual potential to improve insulin resistance (IR) and hepatic steatosis associated with obesity in the liver. Recent studies have demonstrated that ACE2 can regulate the GABA signal in various tissues. Notwithstanding this evidence, the functional relationship between ACE2 and GABA signal in the liver under IR remains elusive. Here, we used high-fat diet-induced models of IR in C57BL/6 mice as well as ACE2KO and adeno-associated virus-mediated ACE2 overexpression mouse models to address this knowledge gap. Our analysis showed that glutamate decarboxylase (GAD)67/GABA signaling was weakened in the liver during IR, whereas the expression of GAD67 and GABA decreased significantly in ACE2KO mice. Furthermore, exogenous administration of angiotensin 1-7 and adeno-associated virus- or lentivirus-mediated overexpression of ACE2 significantly increased hepatic GABA signaling in models of IR both in vivo and in vitro. We found that this treatment prevented lipid accumulation and promoted fatty acid β oxidation in hepatocytes as well as inhibited the expression of gluconeogenesis- and inflammation-related genes, which could be reversed by allylglycine, a specific GAD67 inhibitor. Collectively, our findings show that signaling via the ACE2/A1-7/MAS axis can improve hepatic IR by regulating hepatic GABA signaling. We propose that this research might indicate a potential strategy for the management of diabetes.

Galaxaura elongata Extract (GE) Modulates Vanadyl Sulfate-Induced Renal Damage via Regulating TGF-β/Smads and Nrf2/NF-κB Pathways

Nephrotoxicity becomes a provoked problem as the kidneys are the target of many chemotherapies. For this reason, we aimed to study the protective effect of Galaxaura elongata extract (GE) against the vanadyl sulfate (Van) induced nephrotoxicity in rats. Forty Wistar albino rats (male) were divided into four groups (n = 10) as follows: control group: rats received 0.5% carboxymethyl cellulose (CMC). Galaxa group: rats received GE at a dose (100 mg/kg orally) daily for 6 weeks. Van group: rats injected with Van at a dose (50 mg/kg i.p.) once weekly for 6 successive weeks. Galaxa + Van group: rats received GE at a dose (100 mg/kg orally) daily for 6 weeks concurrently with Van at a dose (50 mg/kg i.p.) for 6 weeks. Our results showed that Van significantly raised urea and creatinine serum levels as compared to the control group as well as disordered renal oxidative/antioxidant redox. Administration of GE with Van alleviated the adverse impact of Van over the kidney tissues. Furthermore, GE administration in Galaxa + Van group downregulates angiotensin-converting enzyme (ACE1) mRNA expression, angiotensin II (Ang II) concentration, transforming growth factor β (TGF-β) mRNA expression and protein concentration and Nuclear factor κB (NF-κB) mRNA expression as compared to Van group. Also, GE administration caused a noticeable upregulation of Nrf2 and heme oxygenase-1 (HO-1) expressions with a consequent decrease of DNA fragmentation % compared to Van group. The results of the current study show that simultaneous treatment with GE can alleviate nephrotoxicity caused by Van in diabetic rats. The GE treatment of the Van treated animals restored altered renal oxidative/antioxidant redox values towards normal and lessened fibrosis. These results are consistent with these effects being caused by interactions with the TGF-B/Smads and Nrf2/NF-κB signaling pathways.

Chrysin Attenuates Fructose-Induced Nonalcoholic Fatty Liver in Rats via Antioxidant and Anti-Inflammatory Effects: The Role of Angiotensin-Converting Enzyme 2/Angiotensin (1-7)/Mas Receptor Axis

Aim

Nonalcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome, and if untreated, it may propagate into end-stage liver disease. The classical arm of the renin-angiotensin system (RAS) has a fundamental role in triggering oxidative stress and inflammation, which play potential roles in the pathogenesis of NAFLD. However, the nonclassical alternative axis of RAS, angiotensin- (Ang-) converting enzyme 2 (ACE2)/Ang (1-7)/Mas receptor, opposes the actions of the classical arm, mitigates the metabolic dysfunction, and improves hepatic lipid metabolism rendering it a promising protective target against NAFLD. The current study is aimed at investigating the impact of chrysin, a well-known antioxidant flavonoid, on this defensive RAS axis in NAFLD.

Methods

Rats were randomly distributed and treated daily for eight weeks as follows: the normal control, chrysin control (50 mg/kg, p.o), NAFLD group (received 20% fructose in drinking water), and treated groups (25 and 50 mg/kg chrysin given orally and concomitantly with fructose). Diminazene aceturate (DIZE) (15 mg/kg, s.c.) was used as a reference ACE2 activator. Key Findings. High fructose induced significant weight gain, hepatocyte degeneration with fat accumulation, and inflammatory cell infiltration (as examined by H&E staining). This was accompanied by a substantial increase in liver enzymes, glucose, circulating and hepatic triglycerides, lipid peroxides, inflammatory cytokines, and Ang II (the main component of classical RAS). At the same time, protein levels of ACE2, Ang (1-7), and Mas receptors were markedly reduced. Chrysin (25 and 50 mg/kg) significantly ameliorated these abnormalities, with a prominent effect of the dose of 50 mg/kg over DIZE and the lower dose in improving ACE2, Ang (1-7), and Mas. Significance. Chrysin is a promising efficient protective remedy against NAFLD; mechanisms include the activation of ACE2/Ang (1-7)/Mas axis.

Renin–Angiotensin System in Liver Metabolism: Gender Differences and Role of Incretins

The impaired hepatic lipids and carbohydrates metabolism result in various metabolic disorders, including obesity, diabetes, insulin resistance, hyperlipidemia and metabolic syndrome. The renin–angiotensin system (RAS) has been identified in the liver and it is now recognized as an important modulator of body metabolic processes. This review is intended to provide an update of the impact of the renin–angiotensin system on lipid and carbohydrate metabolism, regarding gender difference and prenatal undernutrition, specifically focused on the role of the liver. The discovery of angiotensin-converting enzyme 2 (ACE2) has renewed interest in the potential therapeutic role of RAS modulation. RAS is over activated in non-alcoholic fatty liver disease (NAFLD) and hepatocellular carcinoma. Glucagon-like peptide-1 (GLP-1) has been shown to modulate RAS. The GLP-I analogue liraglutide antagonizes hepatocellular steatosis and exhibits liver protection. Liraglutide has a negative effect on the ACE/AngII/AT1R axis and a positive impact on the ACE2/Ang(1-7)/Mas axis. Activation of the ACE2/Ang(1-7)/Mas counter-regulatory axis is able to prevent liver injuries. Angiotensin(1-7) and ACE2 shows more favorable effects on lipid homeostasis in males but there is a need to do more investigation in female models. Prenatal undernutrition exerts long-term effects in the liver of offspring and is associated with a number of metabolic and endocrine alterations. These findings provide a novel therapeutic regimen to prevent and treat many chronic diseases by accelerating the effect of the ACE2/Ang1-7/Mas axis and inhibiting the ACE/AngII/AT1R axis.

Interaction of Serum Alkaline Phosphatase and Folic Acid Treatment on Chronic Kidney Disease Progression in Treated Hypertensive Adults

The relation of alkaline phosphatase (ALP) with chronic kidney disease (CKD) is still uncertain. We aimed to examine the prospective association between serum ALP and CKD progression, and the modifying effect of serum ALP on folic acid in preventing CKD progression in treated hypertensive patients. This is a post-hoc analysis of 12,734 hypertensive adults with relevant measurements and without liver disease at baseline from the renal sub-study of the China Stroke Primary Prevention Trial, where participants were randomly assigned to daily treatments of 10 mg enalapril and 0.8 mg folic acid, or 10 mg enalapril alone. The primary outcome was CKD progression, defined as a decrease in estimated glomerular filtration rate (eGFR) of ≥30% and to a level of <60 ml/min/1.73 m² if baseline eGFR was ≥60 ml/min/1.73 m²; or a decrease in eGFR of ≥50% if baseline eGFR was <60 ml/min/1.73 m²; or end-stage renal disease. Over a median of 4.4 years, in the enalapril only group, participants with baseline serum ALP≥110IU/L (quartile 4) had a significantly higher risk of CKD progression (3.4% vs 2.3%; adjusted OR,1.61; 95%CI:1.11, 2.32), compared with those with ALP<110IU/L. For those with enalapril and folic acid treatment, compared with the enalapril only treatment, the risk of CKD progression was reduced from 3.4 to 2.1% (adjusted OR, 0.53; 95%CI:0.34, 0.83) among participants with baseline ALP≥110IU/L, whereas there was no significant effect among those with ALP<110IU/L. In hypertensive patients, higher serum ALP was associated with increased risk of CKD progression, and this risk was reduced by 47% with folic acid treatment.

Renin-angiotensin system: Basic and clinical aspects-A general perspective

The renin–angiotensin system (RAS) is one of the most complex hormonal regulatory systems, involving several organs that interact to regulate multiple body functions. The study of this system initially focused on investigating its role in the regulation of both cardiovascular function and related pathologies. From this approach, pharmacological strategies were developed for the treatment of cardiovascular diseases. However, new findings in recent decades have suggested that the RAS is much more complex and comprises two subsystems, the classic RAS and an alternative RAS, with antagonistic effects that are usually in equilibrium. The classic system is involved in pathologies where inflammatory, hypertrophic and fibrotic phenomena are common and is related to the development of chronic diseases that affect various body systems. This understanding has been reinforced by the evidence that local renin–angiotensin systems exist in many tissue types and by the role of the RAS in the spread and severity of COVID-19 infection, where it was discovered that viral entry into cells of the respiratory system is accomplished through binding to angiotensin-converting enzyme 2, which is present in the alveolar epithelium and is overexpressed in patients with chronic cardiometabolic diseases. In this narrative review, preclinical and clinical aspects of the RAS are presented and topics for future research are discussed some aspects are raised that should be clarified in the future and that call for further investigation of this system.

Cirrhosis-Associated RAS-Inflammation-Coagulation Axis Anomalies: Parallels to Severe COVID-19

(1) Background: Cirrhotic patients have an increased risk for severe COVID-19. We investigated the renin-angiotensin-aldosterone system (RAS), parameters of endothelial dysfunction, inflammation, and coagulation/fibrinolysis in cirrhotic patients and in COVID-19 patients. (2) Methods: 127 prospectively characterized cirrhotic patients (CIRR), along with nine patients with mild COVID-19 (mild-COVID), 11 patients with COVID-19 acute respiratory distress syndrome (ARDS; ARDS-COVID), and 10 healthy subjects (HS) were included in the study. Portal hypertension (PH) in cirrhotic patients was characterized by hepatic venous pressure gradient (HVPG). (3) Results: With increased liver disease severity (Child−Pugh stage A vs. B vs. C) and compared to HS, CIRR patients exhibited higher RAS activity (angiotensin-converting enzyme (ACE), renin, aldosterone), endothelial dysfunction (von Willebrand-factor (VWF) antigen), inflammation (C-reactive protein (CRP), interleukin-6 (IL-6)), and a disturbed coagulation/fibrinolysis profile (prothrombin fragment F1,2, D-dimer, plasminogen activity, antiplasmin activity). Increased RAS activity (renin), endothelial dysfunction (vWF), coagulation parameters (D-dimer, prothrombin fragment F1,2) and inflammation (CRP, IL-6) were significantly altered in COVID patients and followed similar trends from mild-COVID to ARDS-COVID. In CIRR patients, ACE activity was linked to IL-6 (ρ = 0.26; p = 0.003), independently correlated with VWF antigen (aB: 0.10; p = 0.001), and was inversely associated with prothrombin fragment F1,2 (aB: −0.03; p = 0.023) and antiplasmin activity (aB: −0.58; p = 0.006), after adjusting for liver disease severity. (4) Conclusions: The considerable upregulation of the RAS in Child−Pugh B/C cirrhosis is linked to systemic inflammation, endothelial dysfunction, and abnormal coagulation profile. The cirrhosis-associated abnormalities of ACE, IL-6, VWF antigen, and antiplasmin parallel those observed in severe COVID-19.

Newly discovered endocrine functions of the liver

The liver, the largest solid visceral organ of the body, has numerous endocrine functions, such as direct hormone and hepatokine production, hormone metabolism, synthesis of binding proteins, and processing and redistribution of metabolic fuels. In the last 10 years, many new endocrine functions of the liver have been discovered. Advances in the classical endocrine functions include delineation of mechanisms of liver production of endocrine hormones [including 25-hydroxyvitamin D, insulin-like growth factor 1 (IGF-1), and angiotensinogen], hepatic metabolism of hormones (including thyroid hormones, glucagon-like peptide-1, and steroid hormones), and actions of specific binding proteins to glucocorticoids, sex steroids, and thyroid hormones. These studies have furthered insight into cirrhosis-associated endocrinopathies, such as hypogonadism, osteoporosis, IGF-1 deficiency, vitamin D deficiency, alterations in glucose and lipid homeostasis, and controversially relative adrenal insufficiency. Several novel endocrine functions of the liver have also been unraveled, elucidating the liver’s key negative feedback regulatory role in the pancreatic α cell-liver axis, which regulates pancreatic α cell mass, glucagon secretion, and circulating amino acid levels. Betatrophin and other hepatokines, such as fetuin-A and fibroblast growth factor 21, have also been discovered to play important endocrine roles in modulating insulin sensitivity, lipid metabolism, and body weight. It is expected that more endocrine functions of the liver will be revealed in the near future.

Renin-angiotensin system: Basic and clinical aspects-A general perspective

The renin–angiotensin system (RAS) is one of the most complex hormonal regulatory systems, involving several organs that interact to regulate multiple body functions. The study of this system initially focused on investigating its role in the regulation of both cardiovascular function and related pathologies. From this approach, pharmacological strategies were developed for the treatment of cardiovascular diseases. However, new findings in recent decades have suggested that the RAS is much more complex and comprises two subsystems, the classic RAS and an alternative RAS, with antagonistic effects that are usually in equilibrium. The classic system is involved in pathologies where inflammatory, hypertrophic and fibrotic phenomena are common and is related to the development of chronic diseases that affect various body systems. This understanding has been reinforced by the evidence that local renin–angiotensin systems exist in many tissue types and by the role of the RAS in the spread and severity of COVID-19 infection, where it was discovered that viral entry into cells of the respiratory system is accomplished through binding to angiotensin-converting enzyme 2, which is present in the alveolar epithelium and is overexpressed in patients with chronic cardiometabolic diseases. In this narrative review, preclinical and clinical aspects of the RAS are presented and topics for future research are discussed some aspects are raised that should be clarified in the future and that call for further investigation of this system.

The mechanisms of renin-angiotensin system in hepatocellular carcinoma: From the perspective of liver fibrosis, HCC cell proliferation, metastasis and angiogenesis, and corresponding protection measures

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide, of which the occurrence and development involve a variety of pathophysiological processes, such as liver fibrosis, hepatocellular malignant proliferation, metastasis, and tumor angiogenesis. Some important cytokines, such as TGF-β, PI3K, protein kinase B (Akt), VEGF and NF-κB, can regulate the growth, proliferation, diffusion, metastasis, and apoptosis of HCC cells by acting on the corresponding signaling pathways. Besides, many studies have shown that the formation of HCC is closely related to the main components of renin-angiotensin system (RAS), such as Ang II, ACE, ACE2, MasR, AT1R, and AT2R. Therefore, this review focused on liver fibrosis, HCC cell proliferation, metastasis, tumor angiogenesis, and corresponding protective measures. ACE-Ang II-AT1 axis and ACE2-Ang-(1-7)-MasR axis were taken as the main lines to introduce the mechanism of RAS in the occurrence and development of HCC, so as to provide references for future clinical work and scientific research.

The association between hypertension and nonalcoholic fatty liver disease (NAFLD): literature evidence and systems biology analysis

Nonalcoholic fatty liver disease (NAFLD) has become a major public health issue as its progression increases risks of multisystem morbidity and mortality. Recent evidence indicates a more complex relationship between hypertension and NAFLD than previously thought. In this study, a comprehensive literature search was used to gather information supporting the comorbidity phenomenon of hypertension and NAFLD. Then, systems biology approach was applied to identify the potential genes and mechanisms simultaneously associated with hypertension and NAFLD. With the help of protein-protein interaction network-based algorithm, we found that the distance between hypertension and NAFLD was much less than random ones. Sixty-four shared genes of hypertension and NAFLD modules were identified as core genes. Kyoto Encyclopedia of Genes and Genomes(KEGG) enrichment analysis indicated that some inflammatory, metabolic and endocrine signals were related to the potential biological functions of core genes. More importantly, drugs used to treat cardiovascular diseases, hypertension, hyperlipidemia, inflammatory diseases and depression could be potential therapeutics against hypertension-NAFLD co-occurrence. After analyzing public OMICs data, ALDH1A1 was identified as a potential therapeutic target, without being affected by reverse causality. These findings give a clue for the potential mechanisms of comorbidity of hypertension and NAFLD and highlight the multiple target-therapeutic strategy of NAFLD for future clinical research.

The differential activation of cardiovascular hormones across distinct stages of portal hypertension predicts clinical outcomes

Background and aims

The cardiovascular hormones renin/angiotensin/aldosterone (RAA), brain-type natriuretic peptide (BNP)and arginine-vasopressin (AVP) are key regulators of systemic circulatory homeostasis in portal hypertension (PH). We assessed (i) the activation of renin, BNP and AVP across distinct stages of PH and (ii) whether activation of these hormones correlates with clinical outcomes.

Methods

Plasma levels of renin, proBNP and copeptin (AVP biomarker) were determined in 663 patients with advanced chronic liver disease (ACLD) undergoing hepatic venous pressure gradient (HVPG) measurement at the Vienna General Hospital between 11/2011 and 02/2019. We stratified for Child stage (A–C), HVPG (6–9 mmHg, 10–15 mmHg, ≥ 16 mmHg) and compensated vs. decompensated ACLD.

Results

With increasing PH, hyperdynamic state was indicated by higher heart rates (6–9 mmHg: median 71.0 [IQR 18.0] bpm, 10–15 mmHg: 76.0 [19.0] bpm, ≥ 16 mmHg: 80.0 [22.0] bpm; p < 0.001), lower mean arterial pressure (6–9 mmHg: 103.0 [13.5] mmHg, 10–15 mmHg: 101.0 [19.5] mmHg, ≥ 16 mmHg: 99.0 [21.0] mmHg; p = 0.032) and lower serum sodium (6–9 mmHg: 139.0 [3.0] mmol/L, 10–15 mmHg: 138.0 [4.0] mmol/L, ≥ 16 mmHg: 138.0 [5.0] mmol/L; p < 0.001). Across HVPG strata (6–9 mmHg vs. 10–15 mmHg vs ≥ 16 mmHg), median plasma levels of renin (21.0 [50.5] vs. 25.1 [70.9] vs. 65.4 [219.6] µIU/mL; p < 0.001), proBNP (86.1 [134.0] vs. 63.6 [118.0], vs. 132.2 [208.9] pg/mL; p = 0.002) and copeptin (7.8 [7.7] vs. 5.6 [8.0] vs. 10.7 [18.6] pmol/L; p = 0.024) increased with severity of PH. Elevated renin levels independently predicted first hepatic decompensation (adjusted hazard ratio [aHR]: 1.69; 95% confidence interval [95% CI] 1.07–2.68; p = 0.025) and mortality in compensated patients (aHR: 3.15; 95% CI 1.70–5.84; p < 0.001) and the overall cohort aHR: 1.42; 95% CI 1.01–2.01; p = 0.046). Elevated copeptin levels predicted mortality in decompensated patients (aHR: 5.77; 95% CI 1.27–26.33; p = 0.024) and in the overall cohort (aHR: 3.29; 95% CI 1.36–7.95; p = 0.008). ProBNP levels did not predict clinical outcomes.

Conclusions

The cardiovascular hormones renin, proBNP and AVP are activated with progression of ACLD and PH. Renin activation is a risk factor for hepatic decompensation and mortality, especially in compensated patients. Increased plasma copeptin is a risk factor for mortality, in particular in decompensated patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12072-021-10203-9.

Could protein content of Urinary Extracellular Vesicles be useful to detect Cirrhosis in Alcoholic Liver Disease?

Alcohol abuse has a high impact on the mortality and morbidity related to a great number of diseases and is responsible for the development of alcoholic liver disease (ALD). It remains challenging to detect and evaluate its severity, which is crucial for prognosis. In this work, we studied if urinary EVs (uEVs) could serve in diagnose and evaluate cirrhosis in ALD. To this purpose, uEVs characterization by cryo-electron microscopy (Cryo-EM), Nanoparticle Tracking Analysis (NTA) and Western blotting (WB) was performed in a cohort of 21 controls and 21 cirrhotic patients. Then, proteomics of uEVs was carried out in a second cohort of 6 controls and 8 patients in order to identify new putative biomarkers for cirrhosis in ALD. Interestingly, uEVs concentration, size and protein composition were altered in cirrhotic patients. From a total of 1304 proteins identified in uEVs, 90 of them were found to be altered in cirrhotic patients. The results suggest that uEVs could be considered as a tool and a supplier of new biomarkers for cirrhosis in ALD, whose application would be especially relevant in chronic patients. Yet, further research is necessary to obtain more relevant result in clinical terms.

Impact of cytokine storm and systemic inflammation on liver impairment patients infected by SARS-CoV-2: Prospective therapeutic challenges

Coronavirus disease 2019 (COVID-19) is a devastating worldwide pandemic infection caused by a severe acute respiratory syndrome namely coronavirus 2 (SARS-CoV-2) that is associated with a high spreading and mortality rate. On the date this review was written, SARS-CoV-2 infected about 96 million people and killed about 2 million people. Several arguments disclosed the high mortality of COVID-19 due to acute respiratory distress syndrome or change in the amount of angiotensin-converting enzyme 2 (ACE2) receptor expression or cytokine storm strength production. In a similar pattern, hepatic impairment patients co-infected with SARS-CoV-2 exhibited overexpression of ACE2 receptors and cytokine storm overwhelming, which worsens the hepatic impairment and increases the mortality rate. In this review, the impact of SARS-CoV-2 on hepatic impairment conditions we overviewed. Besides, we focused on the recent studies that indicated cytokine storm as well as ACE2 as the main factors for high COVID-19 spreading and mortality while hinting at the potential therapeutic strategies.

Inflammasome as an Effective Platform for Fibrosis Therapy

Fibrosis is the final stage of the development of chronic inflammation. It is characterized by excessive deposition of the extracellular matrix, leading to tissue structure damage and organ dysfunction, which is a serious threat to human health and life. However, the molecular mechanism of fibrosis is still unclear. Inflammasome is a molecular complex of proteins that has been becoming a key innate sensor for host immunity and is involved in pyroptosis, pathogen infection, metabolic syndrome, cellular stress, and tumor metastasis. Inflammasome signaling and downstream cytokine responses mediated by the inflammasome have been found to play an important role in fibrosis. The inflammasome regulates the secretion of IL-1β and IL-18, which are both critical for the process of fibrosis. Recently, researches on the function of inflammasome have attracted extensive attention, and data derived from these researches have increased our understanding of the effects and regulation of inflammasome during fibrosis. In this review, we emphasize the growing evidence for both indirect and direct effects of inflammasomes in triggering fibrosis as well as potential novel targets for antifibrotic therapies.

COVID-19-associated liver injury: from bedside to bench

The outbreak of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been a global challenge since December 2019. Although most patients with COVID-19 exhibit mild clinical manifestations, in approximately 5% of these patients, the disease eventually progresses to severe lung injury or even multiorgan dysfunction. This situation represents various challenges to hepatology. In the context of liver injury in patients with COVID-19, several key problems need to be solved. For instance, it is important to determine whether SARS-CoV-2 can directly invade liver, especially when ACE2 appears to be negligibly expressed on hepatocytes. In addition, the mechanisms underlying liver dysfunction in COVID-19 patients are not fully understood, which are likely multifactorial and related to hyperinflammation, dysregulated immune responses, abnormal coagulation and drugs. Here, we systematically describe the potential pathogenesis of COVID-19-associated liver injury and propose several hypotheses about its etiopathogenesis.

The clinical course and prognostic factors of severe COVID-19 in Wuhan, China: A retrospective case-control study

ABSTRACT

With the surge of newly diagnosed and severe cases of coronavirus disease 2019 (COVID-19), the death toll is mounting, this study is aimed to explore the prognostic factors of severe COVID-19. This retrospective study included 122 inpatients diagnosed with COVID-19 from January 13 to February 25, 2020. Univariate and multivariate analysis were used to identity the risk factors, receiver operating characteristics curve (ROC) analysis was used for risk stratification. The baseline neutrophil-to-lymphocyte ratio (NLR) (OR = 1.171, 95%CI = 1.049-1.306, P = .005) and Lactate dehydrogenase (LDH) (OR = 1.007, 95%CI = 1.002-1.011, P = .004) were identified as the independent risk factors for severe COVID-19 conditions, and the NLR-LDH grading system was developed to perform risk stratification. The baseline C-reactive protein (CRP) (OR = 1.019, 95%CI = 1.004-1.306, P = .016) and B-type natriuretic peptide (BNP) (OR = 1.018, 95%CI = 1.004-1.035, P = .007) were identified as the independent predictors for disease progression of severe patients. Accordingly, The NLR-LDH grading system was a useful prognostic tool for the early detection of severe COVID-19. And in the severe patients, CRP and BNP seemed to be helpful for predicting the disease progression or death.

Neuroprotective Effects of Casein-Derived Peptide Met-Lys-Pro (MKP) in a Hypertensive Model

We have previously reported that casein hydrolysate, CH-3, from bovine milk and casein-derived tripeptide Met-Lys-Pro (MKP) has ACE inhibitory activity and reduces blood pressure. In this study, we investigated the therapeutic effects of MKP in a hypertensive rat model (7-week-old male SHRSP/Izm rats). For long term evaluation, rats were fed either a diet containing CH-3 or normal diet. The survival rate of SHRSP rats was significantly improved by intake of CH-3 for 181 days. For short term evaluation, rats were orally administered synthetic tripeptide MKP or distilled water for 4 weeks. MRI study demonstrated that hemorrhagic lesions were observed in two of five rats in the control group, while no hemorrhagic lesions were observed in the MKP group. Volumetric analysis using MRI revealed that MKP administration inhibited atrophy of diencephalic regions. Histological examinations revealed that hemorrhage areas and astrogliosis in the hippocampus and cerebral cortex were lower in the MKP group than in the control group. Gene expression analysis indicated that MKP administration reduced expression of genes related to cerebral circulation insufficiency such as immune responses (Cd74 and Prkcd), response to hypoxia (Ddit4, Apold1, and Prkcd), reactive oxygen species metabolic process (Ddit4 and Pdk4), and apoptotic process (Ddit4, Prkcd, and Sgk1), suggesting that MKP administration prevented cerebral ischemia associated with hypertension. In addition, some genes encoding responses to hormone stimulus (Fos, Dusp1, and Sik1) were also downregulated. Serum aldosterone and corticosterone levels were also significantly decreased following MKP administration. The present study indicates that MKP shows neuroprotective effects in SHRSP rats by regulating cerebral circulation insufficiency and corticoid levels. MKP administration may therefore be a potential therapeutic strategy for hypertensive brain diseases such as cerebrovascular disease.

Liraglutide Attenuates Non-Alcoholic Fatty Liver Disease in Mice by Regulating the Local Renin-Angiotensin System

The renin-angiotensin system (RAS) is involved in the pathogenesis of non-alcoholic fatty liver disease (NAFLD) and represents a potential therapeutic target for NAFLD. Glucagon-like peptide-1 (GLP-1) signaling has been shown to regulate the RAS within various local tissues. In this study, we aimed to investigate the functional relationship between GLP-1 and the local RAS in the liver during NAFLD. Wild-type and ACE2 knockout mice were used to establish a high-fat-induced NAFLD model. After the mice were treated with liraglutide (a GLP-1 analogue) for 4 weeks, the key RAS component genes were up-regulated in the liver of NAFLD mice. Liraglutide treatment regulated the RAS balance, preventing a reduction in fatty acid oxidation gene expression and increasing gluconeogenesis and the expression of inflammation-related genes caused by NAFLD, which were impaired in ACE2 knockout mice. Liraglutide-treated HepG2 cells exhibited activation of the ACE2/Ang1-7/Mas axis, increased fatty acid oxidation gene expression, and decreased inflammation, which could be reversed by A779 and AngII. These results indicate that the local RAS in the liver becomes overactivated in response to NAFLD. Moreover, ACE2 knockout increases the severity of liver steatosis. Liraglutide has a negative and antagonistic effect on the ACE/AngII/AT1R axis, a positive impact on the ACE2/Ang1-7/Mas axis, and is mediated through the PI3K/AKT pathway. This may represent a potential new mechanism by which liraglutide improves NAFLD.

The Role of High Fat Diets and Liver Peptidase Activity in the Development of Obesity and Insulin Resistance in Wistar Rats

High-fat diets (HFD) have been widely associated with an increased risk of metabolic disorders and overweight. However, a high intake of sources that are rich in monounsaturated fatty acids has been suggested as a dietary agent that is able to positively influence energy metabolism and vascular function. The main objective of this study was to analyze the role of dietary fats on hepatic peptidases activities and metabolic disorders. Three diets: standard (S), HFD supplemented with virgin olive oil (VOO), and HFD supplemented with butter plus cholesterol (Bch), were administered over six months to male Wistar rats. Plasma and liver samples were collected for clinical biochemistry and aminopeptidase activities (AP) analysis. The expression of inducible nitric oxide synthase (iNOS) was also determined by Western blot in liver samples. The diet supplement with VOO did not induce obesity, in contrast to the Bch group. Though the VOO diet increased the time that was needed to return to the basal levels of plasma glucose, the fasting insulin/glucose ratio and HOMA2-%B index (a homeostasis model index of insulin secretion and valuation of β-cell usefulness (% β-cell secretion)) were improved. An increase of hepatic membrane-bound dipeptidyl-peptidase 4 (DPP4) activity was found only in VOO rats, even if no differences in fasting plasma glucagon-like peptide 1 (GLP-1) were obtained. Both HFDs induced changes in hepatic pyroglutamyl-AP in the soluble fraction, but only the Bch diet increased the soluble tyrosyl-AP. Angiotensinase activities that are implicated in the metabolism of angiotensin II (AngII) to AngIV increased in the VOO diet, which was in agreement with the higher activity of insulin-regulated-AP (IRAP) in this group. Otherwise, the diet that was enriched with butter increased soluble gamma-glutamyl transferase (GGT) and Leucyl-AP, iNOS expression in the liver, and plasma NO. In summary, VOO increased the hepatic activity of AP that were related to glucose metabolism (DPP4, angiotensinases, and IRAP). However, the Bch diet increased activities that are implicated in the control of food intake (Tyrosine-AP), the index of hepatic damage (Leucine-AP and GGT), and the expression of hepatic iNOS and plasma NO. Taken together, these results support that the source of fat in the diet affects several peptidases activities in the liver, which could be related to alterations in feeding behavior and glucose metabolism.