Nonalcoholic Fatty Liver Disease and the Kidney: A Review

Oxidative stress and inflammation in hemodialysis: a comparison of patients with or without advanced nonalcoholic fatty liver disease (NAFLD)

Nonalcoholic fatty liver disease (NAFLD) and chronic kidney disease are global public health issues associated with high morbidity and mortality. Both diseases are also interlinked. Little is known about the meaning of NAFLD in hemodialysis (HD) patients. Therefore, the aim of our study was to investigate the difference in oxidative stress and inflammation in HD patients with or without advanced NAFLD. Seventy-seven HD patients were included (65.14 ± 12.34 years, 59.2% male) and divided according to abdominal ultrasound and two-dimensional shear wave elastography (2D-SWE) measurements into two groups: 1) no NAFLD or no advanced NAFLD (2D-SWE <9 kPa) and 2) advanced NAFLD (2D-SWE ≥9 kPa). Medical history data and blood results were collected. HD patients with advanced NAFLD had significantly higher levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG; p = 0.025), tumor necrosis factor-alpha (TNF-α; p = 0.023), and intercellular adhesion molecule 1 (ICAM-1; p = 0.015) in comparison to HD patients without advanced NAFLD. Interleukin 6 (IL-6) was higher in the advanced NAFLD group, but the difference was of borderline significance (p = 0.054). There was no significant difference in high-sensitivity C-reactive protein (hs-CRP), and vascular cell adhesion molecule 1 (VCAM-1) between groups. In binary logistic regression analysis, advanced NAFLD was significantly associated with 8-OHdG and ICAM-1. In conclusion, higher oxidative stress and inflammation levels are present in HD patients with advanced NAFLD.

The Effect of Backscatter Anisotropy in Assessing Hepatic Steatosis Using Ultrasound Hepatorenal Index

OBJECTIVES

To discuss challenges in assessing hepatic steatosis using ultrasound hepatorenal index (HRI).

METHODS

We retrospectively analyzed HRI and liver magnetic resonance imaging-based proton density fat fraction (MRI-PDFF) in 134 adult participants (53 men and 81 women, mean age 55 years). The diagnostic performance of HRI for determining hepatic steatosis was tested by the area under the receiver operating characteristic curve (AUROC) using liver MRI-PDFF as the reference. Regression plots were employed to compare the sampling sites in liver and kidney that were used to calculate HRIs.

RESULTS

In 11 of 134 cases (8.2%), we failed to acquire HRI measurements. In the remaining 123 cases, AUROC for HRI (cutoff: 1.69 ± 0.13 [mean ± standard deviation]) for defining the HRI threshold for diagnosing hepatic steatosis was 0.83. In 60 of 123 cases (49%) with HRI measurement IQR/median >0.3, slopes of the regression lines in the liver showed backscatter intensity changes consistent with signal attenuation. However, in the kidney, the backscatter intensity was inverted yielding position-dependent HRI cutoff values, mid-pole = 2.24 ± 0.20 and upper pole = 1.08 ± 0.16.

CONCLUSIONS

HRI is used to estimate liver steatosis based on backscattered ultrasound. In order to compensate for effects such as body habitus and transducer frequency, the liver backscatter is divided by backscatter from a corresponding region at the same depth in the right renal cortex. Theoretically, this compensation should make HRI sampling position independent. Yet, due to renal cortical backscatter anisotropy, this compensation method does not work in general, potentially producing inaccurate liver fat estimates.

From Liver to Kidney: The Overlooked Burden of Nonalcoholic Fatty Liver Disease in Chronic Kidney Disease

Nonalcoholic fatty liver disease (NAFLD) is increasingly recognized as a contributor to chronic kidney disease (CKD), yet its impact remains underappreciated in clinical practice. Recent studies reveal a strong association between NAFLD and CKD progression, with evidence linking hepatic dysfunction to renal impairment through metabolic and inflammatory pathways. NAFLD not only increases the risk of CKD but also accelerates its progression, leading to worse cardiovascular outcomes and higher mortality, particularly in patients with advanced fibrosis. Despite this growing evidence, NAFLD often goes undiagnosed in CKD patients and routine hepatic evaluation is rarely integrated into nephrology care. Emerging diagnostic tools, including noninvasive biomarkers and imaging techniques, offer potential for earlier detection, yet their clinical implementation remains inconsistent. Although lifestyle modifications remain the foundation of treatment, pharmacotherapeutic strategies, including SGLT2 inhibitors and GLP-1 receptor agonists, have demonstrated potential in mitigating both hepatic and renal impairment. Recognizing the interplay between NAFLD and CKD is essential for improving patient outcomes. A multidisciplinary approach, integrating hepatology and nephrology expertise, is crucial to refining screening strategies, optimizing treatment, and reducing the long-term burden of these coexisting conditions.

The pleiotropic effects of glucagon-like peptide-1 receptor agonists in patients with metabolic dysfunction-associated steatohepatitis: a review for gastroenterologists

INTRODUCTION

Glucagon-like peptide-1 receptor agonists (GLP-1RAs), and dual GLP-1/glucose-dependent insulinotropic peptide (GIP) or glucagon receptor agonists have emerged as promising agents to treat metabolic dysfunction-associated steatotic liver disease (MASLD)/metabolic dysfunction-associated steatohepatitis (MASH). Although the beneficial effects of GLP-1RAs on glycemic control and weight are well-established, clinicians may be unfamiliar with other potential benefits of this class.

AREAS COVERED

We examined the pleiotropic effects of GLP-1RAs and how they relate to gastroenterologists for MASLD/MASH treatment. Our narrative review of English articles included four GLP-1RAs (subcutaneous semaglutide, liraglutide, dulaglutide, and efpeglenatide), a dual GLP-1/GIP agonist (tirzepatide), a dual GLP-1/glucagon receptor agonist (survodutide), MASLD/MASH, related disorders, clinical management, treatment outcomes and landscape.

EXPERT OPINION

In Phase I - III trials, GLP-1RAs are associated with clinically relevant hepatic improvements including MASH resolution, liver fat reduction, and preventing worsening fibrosis. Effects on cardiometabolic parameters align with type 2 diabetes/obesity Phase III data, comprising substantial improvements in glycemic, weight, and cardiovascular outcomes. Promising data also suggest benefits in common comorbidities, including obstructive sleep apnea, polycystic ovary syndrome, chronic kidney disease, and heart failure with preserved ejection fraction.GLP-1RAs represent a valuable pharmacotherapeutic option for gastroenterologists managing individuals with MASLD/MASH and cardiometabolic comorbid conditions.

Glucagon and glucagon-like peptide-1 dual agonist therapy: A possible future towards fatty kidney disease

BACKGROUND

Obesity is a growing epidemic affecting approximately 40% of the adult population in developed countries with major health consequences and comorbidities, including diabetes mellitus and insulin resistance, metabolically associated fatty liver disease, atherosclerotic cardiovascular and cerebrovascular diseases and chronic kidney disease. Pharmacotherapies targeting significant weight reduction may have beneficial effects on such comorbidities, though such therapeutic options are highly limited. In this narrative review, we aim to evaluate current knowledge regarding dual agonist therapies and potential implications for managing fatty kidney and chronic kidney disease.

RESULTS AND CONCLUSION

Glucagon-like peptide-1 agonists and sodium-glucose cotransporter-2 inhibitors are two novel classes of glucose-lowering medications with potential implications and beneficiary effects on renal outcomes, including estimated glomerular filtration rate, albuminuria and chronic kidney disease progression. Recently, dual agonist therapies targeting glucagon-like peptide-1 and glucagon receptors, namely survodutide and cotadutide, have been evaluated in managing metabolically associated fatty liver disease, a well-established example of visceral obesity. Fatty kidney is another novel concept implicated in the pathophysiology of chronic kidney disease among patients with visceral obesity.

Alpha-1 antitrypsin deficiency and Pi*Z allele as important co-factors in the development of liver fibrosis

BACKGROUND

Alpha-1 antitrypsin deficiency (AATD) is a codominant autosomal hereditary condition that predisposes patients to the development of lung and/or liver disease, and Pi*Z allele is the most clinically relevant mutation.

AIM

To evaluate the impact of clinical parameters and AATD phenotypes, particularly the Pi*Z allele, in liver fibrosis.

METHODS

Cross-sectional cohort study including consecutive patients with AATD followed in Pulmonology or Hepatology consultation.

RESULTS

Included 69 patients, 49.3% had Pi*MZ phenotype and 10.1% Pi*ZZ. An age ≥ 55 years, age at diagnosis ≥ 41 years and AAT at diagnosis < 77 mg/dL predicted a nonalcoholic fatty liver disease fibrosis score (NFS) not excluding advanced fibrosis [area under the curve (AUC) = 0.840, P < 0.001; AUC = 0.836, P < 0.001; AUC = 0.681, P = 0.025]. An age ≥ 50 years and age at diagnosis ≥ 41 years predicted a fibrosis-4 index of moderate to advanced fibrosis (AUC = 0.831, P < 0.001; AUC = 0.795, P < 0.001). Patients with hypertension, type 2 diabetes mellitus (DM), dyslipidaemia, metabolic syndrome, and regular alcohol consumption were more likely to have a NFS not excluding advanced fibrosis (P < 0.001, P = 0.002, P = 0.008, P < 0.001, P = 0.033). Patients with at least one Pi*Z allele and type 2 DM were 8 times more likely to have liver stiffness measurement ≥ 7.1 kPa (P = 0.040).

CONCLUSION

Risk factors for liver disease in AATD included an age ≥ 50 years, age at diagnosis ≥ 41 years, metabolic risk factors, regular alcohol consumption, at least one Pi*Z allele, and AAT value at diagnosis < 77 mg/dL. We created an algorithm for liver disease screening in AATD patients to use in primary care, selecting those to be referred to Hepatology consultation.

Systemic impacts of metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH) on heart, muscle, and kidney related diseases

Metabolic dysfunction-associated steatotic liver disease (MASLD), previously known as non-alcoholic fatty liver disease (NAFLD), is the most common liver disorder worldwide, with an estimated global prevalence of more than 31%. Metabolic dysfunction-associated steatohepatitis (MASH), formerly known as non-alcoholic steatohepatitis (NASH), is a progressive form of MASLD characterized by hepatic steatosis, inflammation, and fibrosis. This review aims to provide a comprehensive analysis of the extrahepatic manifestations of MASH, focusing on chronic diseases related to the cardiovascular, muscular, and renal systems. A systematic review of published studies and literature was conducted to summarize the findings related to the systemic impacts of MASLD and MASH. The review focused on the association of MASLD and MASH with metabolic comorbidities, cardiovascular mortality, sarcopenia, and chronic kidney disease. Mechanistic insights into the concept of lipotoxic inflammatory "spill over" from the MASH-affected liver were also explored. MASLD and MASH are highly associated (50%-80%) with other metabolic comorbidities such as impaired insulin response, type 2 diabetes, dyslipidemia, hypertriglyceridemia, and hypertension. Furthermore, more than 90% of obese patients with type 2 diabetes have MASH. Data suggest that in middle-aged individuals (especially those aged 45-54), MASLD is an independent risk factor for cardiovascular mortality, sarcopenia, and chronic kidney disease. The concept of lipotoxic inflammatory "spill over" from the MASH-affected liver plays a crucial role in mediating the systemic pathological effects observed. Understanding the multifaceted impact of MASH on the heart, muscle, and kidney is crucial for early detection and risk stratification. This knowledge is also timely for implementing comprehensive disease management strategies addressing multi-organ involvement in MASH pathogenesis.

New perspectives on the therapeutic potential of quercetin in non-communicable diseases: Targeting Nrf2 to counteract oxidative stress and inflammation

Non-communicable diseases (NCDs), including cardiovascular diseases, cancer, metabolic diseases, and skeletal diseases, pose significant challenges to public health worldwide. The complex pathogenesis of these diseases is closely linked to oxidative stress and inflammatory damage. Nuclear factor erythroid 2-related factor 2 (Nrf2), a critical transcription factor, plays an important role in regulating antioxidant and anti-inflammatory responses to protect the cells from oxidative damage and inflammation-mediated injury. Therefore, Nrf2-targeting therapies hold promise for preventing and treating NCDs. Quercetin (Que) is a widely available flavonoid that has significant antioxidant and anti-inflammatory properties. It modulates the Nrf2 signaling pathway to ameliorate oxidative stress and inflammation. Que modulates mitochondrial function, apoptosis, autophagy, and cell damage biomarkers to regulate oxidative stress and inflammation, highlighting its efficacy as a therapeutic agent against NCDs. Here, we discussed, for the first time, the close association between NCD pathogenesis and the Nrf2 signaling pathway, involved in neurodegenerative diseases (NDDs), cardiovascular disease, cancers, organ damage, and bone damage. Furthermore, we reviewed the availability, pharmacokinetics, pharmaceutics, and therapeutic applications of Que in treating NCDs. In addition, we focused on the challenges and prospects for its clinical use. Que represents a promising candidate for the treatment of NCDs due to its Nrf2-targeting properties.

Serum Phosphorus, Serum Bicarbonate, and Renal Function in Relation to Liver CYP1A2 Activity

The liver plays an important role in normal metabolism and physiological functions such as acid-base balance; however, limited epidemiologic studies have investigated how the liver contributes toward acid-base balance using non-invasive biomarkers. We determined associations between serum biomarkers related to acid-base balance and renal function with liver CYP1A2 activity. We used data from 1381 participants of the 2009-2010 National Health and Nutrition Examination Survey (NHANES) with measurements of serum phosphorus, serum bicarbonate, caffeine intake, caffeine metabolites, and estimated glomerular filtration rate (eGFR). Liver CYP1A2 activity was estimated using urine caffeine metabolite indices, which were calculated as the ratio of one of the urine caffeine metabolites (i.e., paraxanthine and 1-methyluric acid) to caffeine intake. We analyzed associations in the whole data set and in different strata of hepatic steatosis index (HSI) based on different cut-points. We found that serum bicarbonate was positively associated with CYP1A2 activity in the whole data set when comparing persons with bicarbonate at Q4 to Q1 (β = 0.18, p = 0.10 for paraxanthine; β = 0.20, p = 0.02 for 1-methyluric acid). Furthermore, serum phosphorus was positively associated with CYP1A2 activity only in the stratum of 30 ≤ HSI < 36. Lastly, low eGFR was significantly associated with lower CYP1A2 activity measured with paraxanthine in the whole dataset and in all the strata with HSI < 42; when comparing eGFR < 60 to eGFR > 90, β estimates ranged from -0.41 to -1.38, p-values ranged from 0.0018 to 0.004. We observed an opposite trend in the highest stratum (HSI ≥ 42). Non-invasive measurements of serum bicarbonate, serum phosphorus, and eGFR have dynamic associations with CYP1A2 activity. These associations depend on the extent of liver damage and the caffeine metabolite used to assess CYP1A2 activity.

The liver-kidney axis: Is serum leptin a potential link in non-alcoholic fatty liver disease-associated chronic kidney disease?

BACKGROUND AND STUDY AIMS

Non-alcoholic fatty liver disease (NAFLD) is an independent risk factor for chronic kidney disease (CKD). Previous studies argued that leptin levels increase significantly with the progression of CKD. But the association between leptin and CKD has not been investigated in patients with NAFLD. Therefore, we conducted this study to establish whether increased leptin level is associated with CKD in NAFLD patients.

PATIENTS AND METHODS

In our prospective study with a follow up period of six months thirty-five teetotaller biopsy-proven NAFLD patients were divided as groups with mild, versus advanced, fibrosis. Liver fibrosis was also assessed with Fibroscan. Serum leptin levels were measured by radioimmunoassay. For insulin resistance we used the homeostasis model assessment method (HOMA-IR). For the kidney function, we used the abbreviated formula Modification of Diet in Renal Disease (MDRD) formula, which estimates GFR. For statistical analysis, Student's-t test, Mann-Whitney test, linear regression-binary logistic regression analyses and the ROC curve analysis were used.

RESULTS

Advanced fibrosis and increased HOMA-IR were risk factors for decreased eGFR. Leptin correlated inversely with advanced fibrosis (p: 0.03) and low leptin was a risk factor for CKD (p: 0.02). In ROC curve analysis, advanced fibrosis and low leptin were risk factors for decreased eGFR (p: 0.007 and 0.004, respectively). Low leptin level was dependently associated with decreased eGFR.

CONCLUSION

Advanced fibrosis in NAFLD patients is a risk factor for CKD. Leptin correlated inversely with advanced fibrosis. Unlike the previous studies, which were not performed in NAFLD patients, we found decreased leptin in NAFLD patients with decreased eGFR. Low leptin level was found to be a dependent predictor for differentiating NAFLD patients with high risk for CKD.

Therapeutic potential of dietary flavonoid hyperoside against non-communicable diseases: targeting underlying properties of diseases

Non-communicable diseases (NCDs) are a global epidemic with diverse pathogenesis. Among them, oxidative stress and inflammation are the most fundamental co-morbid features. Therefore, multi-targets and multi-pathways therapies with significant anti-oxidant and anti-inflammatory activities are potential effective measures for preventing and treating NCDs. The flavonol glycoside compound hyperoside (Hyp) is widely found in a variety of fruits, vegetables, beverages, and medicinal plants and has various health benefits, especially excellent anti-oxidant and anti-inflammatory properties targeting nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor-κB (NF-κB) signaling pathways. In this review, we summarize the pathogenesis associated with oxidative stress and inflammation in NCDs and the biological activity and therapeutic potential of Hyp. Our findings reveal that the anti-oxidant and anti-inflammatory activities regulated by Hyp are associated with numerous biological mechanisms, including positive regulation of mitochondrial function, apoptosis, autophagy, and higher-level biological damage activities. Hyp is thought to be beneficial against organ injuries, cancer, depression, diabetes, and osteoporosis, and is a potent anti-NCDs agent. Additionally, the sources, bioavailability, pharmacy, and safety of Hyp have been established, highlighting the potential to develop Hyp into dietary supplements and nutraceuticals.

Metabolic Syndrome but Not Fatty Liver-Associated Genetic Variants Correlates with Glomerular Renal Function Decline in Patients with Non-Alcoholic Fatty Liver Disease

The association between non-alcoholic fatty liver disease (NAFLD) and chronic kidney disease (CKD) has been extensively demonstrated. Recent studies have focused attention on the role of patatin-like phospholipase domain-containing 3 (PNPLA3) rs738409 polymorphism in the association between NAFLD and CKD in non-metabolic adults and children, but the genetic impact on NAFLD-CKD association is still a matter of debate. The aim of the study was to investigate the impact of PNPLA3, transmembrane 6 superfamily member 2 (TM6SF2), membrane-bound O-acyltransferase domain containing 7 (MBOAT7) and glucokinase regulatory protein (GCKR) gene variants rather than metabolic syndrome features on renal function in a large population of NAFLD patients. The present study is a post hoc analysis of the Plinio Study (ClinicalTrials.gov: NCT04036357). PNPLA3, TM6SF2, MBOAT7 and GCKR genes were analyzed by using real-time PCR with TaqMan probes. Glomerular filtration rate (GFR) was estimated with CKD-EPI. We analyzed 538 NAFLD; 47.2% had GFR < 90 mL/min/1.73 m2 while 5.9% had GFR < 60 mL/min/1.73 m2. The distribution of genotypes was superimposable according to GFR cut-offs. Results from the multivariable regression model did not show any correlation between genotypes and renal function. Conversely, metabolic syndrome was highly associated with GFR < 90 mL/min/1.73 m2 (odds ratio (OR): 1.58 [1.10−2.28]) and arterial hypertension with GFR < 60 mL/min/1.73 m2 (OR: 1.50 [1.05−2.14]). In conclusion, the association between NAFLD and CKD might be related to the shared metabolic risk factors rather than the genetic NAFLD background.

Decrease in Sleep Duration and Poor Sleep Quality over Time Is Associated with an Increased Risk of Incident Non-Alcoholic Fatty Liver Disease

The impact of changes in sleep duration and sleep quality over time on the risk of non-alcoholic fatty liver disease (NAFLD) is not known. We investigated whether changes in sleep duration and in sleep quality between baseline and follow-up are associated with the risk of developing incident NAFLD. The cohort study included 86,530 Korean adults without NAFLD and with a low fibrosis score at baseline. The median follow-up was 3.6 years. Sleep duration and quality were assessed using the Pittsburgh Sleep Quality Index. Hepatic steatosis (HS) and liver fibrosis were assessed using ultrasonography and the fibrosis-4 index (FIB-4). Cox proportional hazard models were used to determine hazard ratios (HRs) and 95% confidence intervals (Cis). A total of 12,127 subjects with incident HS and 559 with incident HS plus intermediate/high FIB-4 was identified. Comparing the decrease in sleep duration of >1 h, with stable sleep duration, the multivariate-adjusted HR (95% CIs) for incident HS was 1.24 (1.15–1.35). The corresponding HRs for incident HS plus intermediate/high FIB-4 was 1.58 (1.10–2.29). Comparing persistently poor sleep quality with persistently good sleep quality, the multivariate-adjusted HR for incident HS was 1.13 (95% CI, 1.05–1.20). A decrease in sleep duration or poor sleep quality over time was associated with an increased risk of incident NAFLD, underscoring an important potential role for good sleep in preventing NAFLD risk.