Fatty Liver and Chronic Kidney Disease: Novel Mechanistic Insights and Therapeutic Opportunities

Renal Complications in Portal Hypertension

Acute kidney injury (AKI) is a common complication among patients with decompensated cirrhosis and its development is associated with worse prognosis in terms of survival. Patients with decompensated cirrhosis may develop a unique type of AKI, known as hepatorenal syndrome (HRS-AKI), characterized by marked impairment of kidney function due to haemodynamic changes that occur in late stages of liver cirrhosis. Besides, patients with cirrhosis also may develop chronic alterations of kidney function (chronic kidney disease, CKD), the incidence of which is increasing markedly and may be associated with clinical complications. The aim of this review is to provide the reader with an update of the most relevant aspects of alterations of kidney function in patients with cirrhossi that may be useful for theri clinical practice.

Treatment Options and Continuity of Care in Metabolic-associated Fatty Liver Disease: A Multidisciplinary Approach

The terms non-alcoholic fatty liver disease and non-alcoholic steatohepatitis have some limitations as they use exclusionary confounder terms and the use of potentially stigmatising language. Recently, a study with content experts and patients has been set to change this nomenclature. The term chosen to replace non-alcoholic fatty liver disease was metabolic dysfunction-associated steatotic liver disease (MASLD), which avoids stigmatising and helps improve awareness and patient identification. MASLD is the most common cause of chronic liver disease with an increasing prevalence, accounting for 25% of the global population. It is considered the hepatic manifestation of the metabolic syndrome with lifestyle playing a fundamental role in its physiopathology. Diet change and physical activity are the cornerstones of treatment, encompassing weight loss and healthier behaviours and a holistic approach. In Europe, there is no approved drug for MASLD to date and there is a substantial unmet medical need for effective treatments for patients with MASLD. This review not only provides an update on advances in evidence for nutrition and physical activity interventions but also explores the different therapeutic options that are being investigated and whose development focuses on the restitution of metabolic derangements and halting inflammatory and fibrogenic pathways.

Effect of phospholipid curcumin Meriva on liver histology and kidney disease in nonalcoholic steatohepatitis: A randomized, double-blind, placebo-controlled trial

BACKGROUND AND AIMS

NASH confers an increased liver-related and kidney morbidity. Phospholipid curcumin (Meriva) is a phospholipid formulation with ameliorated systemic curcumin absorption and delivery. We assessed the safety and efficacy of Meriva in NASH.

APPROACH AND RESULTS

In this double-blind trial, 52 patients with biopsy-proven NASH (71% with stage ≥F2 fibrosis, 58% with stage A2-G2/A2-G3a chronic kidney disease) were randomized 1:1 to receive Meriva 2 g/d or placebo for 72 weeks. The primary endpoint was NASH resolution with no worsening of fibrosis. The secondary endpoints included a ≥1 stage liver fibrosis improvement with no NASH worsening; regression of significant (ie, stage ≥F2) fibrosis and CKD; and improvement in renal, glucose, lipid, and inflammatory parameters. We also explored the treatment effect on hepatic activation of NF-kB, a key proinflammatory transcription factor and a major target of curcumin. Fifty-one patients (26 on Meriva and 25 on placebo) completed the trial. Sixteen (62%) patients on Meriva versus 3 (12%) patients on placebo had NASH resolution (RR = 5.33 [95% CI = 1.76-12.13]; p = 0.003). Thirteen (50%) patients on Meriva versus 2 (8%) patients on placebo had ≥1 stage fibrosis improvement (RR = 6.50 [1.63-21.20]; p = 0.008). Eleven (42%) patients on Meriva versus 0 (0%) on placebo had regression of significant liver fibrosis (RR = 18.01 [1.43-36.07]; p = 0.02). Hepatic NF-kB inhibition predicted NASH resolution (AUC = 0.90, 95% CI = 0.84-0.95) and fibrosis improvement (AUC = 0.89, 95% CI = 0.82-0.96). Thirteen (50%) patients on Meriva versus 0 (0%) on placebo had chronic kidney disease regression (RR = 10.71 [1.94-17.99)]; p = 0.004). Compared with placebo, Meriva improved eGFR (difference in adjusted eGFR change: +3.59 [2.96-4.11] mL/min/1.73 m 2 /y, p = 0.009), fasting glucose(-17 mg/dL; 95% CI = -22, -12), HbA1c (-0.62%; 95% CI = -0.87%, -0.37%), LDL-C (-39 mg/dL; 95% CI = -45, -33), triglycerides (-36 mg/dL, 95% CI = -46, -26), HDL-C (+10 mg/dL; 95% CI = +8, +11), and inflammatory markers. Adverse events were rare, mild, and evenly distributed.

CONCLUSIONS

In patients with NASH, Meriva administration for 72 weeks was safe, well-tolerated, and improved liver histology, possibly through NF-kB inhibition, kidney disease, and metabolic profile.

Renal tubule-specific Atgl deletion links kidney lipid metabolism to glucagon-like peptide 1 and insulin secretion independent of renal inflammation or lipotoxicity

OBJECTIVE

Lipotoxic injury from renal lipid accumulation in obesity and type 2 diabetes (T2D) is implicated in associated kidney damage. However, models examining effects of renal ectopic lipid accumulation independent of obesity or T2D are lacking. We generated renal tubule-specific adipose triglyceride lipase knockout (RT-SAKO) mice to determine if this targeted triacylglycerol (TAG) over-storage affects glycemic control and kidney health.

METHODS

Male and female RT-SAKO mice and their control littermates were tested for changes in glycemic control at 10-12 and 16-18 weeks of age. Markers of kidney health and blood lipid and hormone concentrations were analyzed. Kidney and blood lysophosphatidic acid (LPA) levels were measured, and a role for LPA in mediating impaired glycemic control was evaluated using the LPA receptor 1/3 inhibitor Ki-16425.

RESULTS

All groups remained insulin sensitive, but 16- to 18-week-old male RT-SAKO mice became glucose intolerant, without developing kidney inflammation or fibrosis. Rather, these mice displayed lower circulating insulin and glucagon-like peptide 1 (GLP-1) levels. Impaired first-phase glucose-stimulated insulin secretion was detected and restored by Exendin-4. Kidney and blood LPA levels were elevated in older male but not female RT-SAKO mice, associated with increased kidney diacylglycerol kinase epsilon. Inhibition of LPA-mediated signaling restored serum GLP-1 levels, first-phase insulin secretion, and glucose tolerance.

CONCLUSIONS

TAG over-storage alone is insufficient to cause renal tubule lipotoxicity. This work is the first to show that endogenously derived LPA modulates GLP-1 levels in vivo, demonstrating a new mechanism of kidney-gut-pancreas crosstalk to regulate insulin secretion and glucose homeostasis.

Hepatic steatosis index at diagnosis has the potential for forecasting end-stage kidney disease in patients with antineutrophil cytoplasmic antibody-associated vasculitis

Objective

This study evaluated whether the hepatic steatosis index (HSI) at antineutrophil cytoplasmic antibody-associated vasculitis (AAV) diagnosis could forecast poor outcomes during the disease course in AAV patients.

Methods

This study included 260 AAV patients. The equation for HSI is as follows HSI=8×(alanine aminotransferase/aspartate aminotransferase)+body mass index+(2, diabetes mellitus)+(2, female). The cut-off of HSI was obtained using the receiver operating characteristic curve.

Results

The median age of the 260 patients was 59.5 years, and 65.0% were female. Among the continuous variables excluding the parameters composing the equation for HSI, HSI was significantly correlated with Birmingham vasculitis activity score, five-factor score, haemoglobin, blood urea nitrogen, serum creatinine, and total cholesterol. Among poor outcomes, the area under the curve of HSI for end-stage renal disease (ESRD) was significant, and the cut-off of HSI for ESRD was set at ≤30.82. AAV patients with HSI ≤30.82 exhibited a significantly higher risk of ESRD (relative risk 3.489) and a significantly lower cumulative ESRD-free survival rate than those with HSI >30.82.

Conclusion

This study is the first to demonstrate that HSI at AAV diagnosis could forecast ESRD during the disease course in AAV patients.

Targeting Renal Proximal Tubule Cells in Obesity-Related Glomerulopathy

As a metabolic disorder, obesity can cause secondary kidney damage, which is called obesity-related glomerulopathy (ORG). As the incidence of obesity increases worldwide, so does the incidence of end-stage renal disease (ESRD) caused by ORGs. However, there is still a lack of effective strategies to prevent and delay the occurrence and development of ORG. Therefore, a deeper understanding and elaboration of the pathogenesis of ORG is conducive to the development of therapeutic drugs for ORG. Here, we review the characteristics of pathological lesions of ORG and describe the roles of lipid metabolism disorders and mitochondrial oxidative stress in the development of ORG. Finally, we summarize the current available drugs or compounds for the treatment of ORG and suggested that ameliorating renal lipid metabolism and mitochondrial function may be potential therapeutic targets for ORG.

Hepatic Fibrosis Evaluated in Patients with Type 2 Diabetes with and without Chronic Kidney Disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD), and particularly liver fibrosis, has been suggested as a risk factor of chronic kidney disease (CKD). Given that NAFLD affects every fourth person globally, better insight is needed. Our aim was to investigate the association between hepatic fibrosis and CKD in patients with type 2 diabetes and to compare different methods for diagnosing liver fibrosis in this study population.

METHODS

Cross-sectional study including patients with type 2 diabetes with CKD stages 3-5 (N = 50) or without CKD (N = 50). CKD was defined as estimated glomerular filtration rate <60 mL/min/1.73 m2 with or without proteinuria. Three methods were used to detect significant liver fibrosis defined as either ≥8 kilopascal measured by transient elastography (FibroScan®), fibrosis-4 (FIB-4) score ≥2.67, or NAFLD fibrosis score (NFS) >0.675.

RESULTS

Significant liver fibrosis was found in 38% and 28% of the patients with and without CKD, respectively, using at least one of the three methods. Both FIB-4 score and NFS were significantly higher in patients with CKD (p < 0.0009 and p < 0.0001, respectively), although insignificant after adjustments for age, sex, body mass index, and duration of diabetes. In patients without CKD, a significant association between steatosis and fibrosis was observed (p = 0.0007).

CONCLUSION

Our data do not support any strong independent association between liver fibrosis and established CKD as assessed by FibroScan, FIB-4 score, and NFS, respectively.

Clinical Prospect of Mesenchymal Stromal/Stem Cell-Derived Extracellular Vesicles in Kidney Disease: Challenges and the Way Forward

Kidney disease is a growing public health problem worldwide, including both acute and chronic forms. Existing therapies for kidney disease target various pathogenic mechanisms; however, these therapies only slow down the progression of the disease rather than offering a cure. One of the potential and emerging approaches for the treatment of kidney disease is mesenchymal stromal/stem cell (MSC) therapy, shown to have beneficial effects in preclinical studies. In addition, extracellular vesicles (EVs) released by MSCs became a potent cell-free therapy option in various preclinical models of kidney disease due to their regenerative, anti-inflammatory, and immunomodulatory properties. However, there are scarce clinical data available regarding the use of MSC-EVs in kidney pathologies. This review article provides an outline of the renoprotective effects of MSC-EVs in different preclinical models of kidney disease. It offers a comprehensive analysis of possible mechanisms of action of MSC-EVs with an emphasis on kidney disease. Finally, on the journey toward the implementation of MSC-EVs into clinical practice, we highlight the need to establish standardized methods for the characterization of an EV-based product and investigate the adequate dosing, safety, and efficacy of MSC-EVs application, as well as the development of suitable potency assays.

Insulin resistance and adipose tissue interactions as the cornerstone of metabolic (dysfunction)-associated fatty liver disease pathogenesis

The relationship between metabolic derangements and fatty liver development are undeniable, since more than 75% of patients with type 2 diabetes mellitus present with fatty liver. There is also significant epidemiological association between insulin resistance (IR) and metabolic (dysfunction)-associated fatty liver disease (MAFLD). For little more than 2 years, the nomenclature of fatty liver of non-alcoholic origin has been intended to change to MAFLD by multiple groups. While a myriad of reasons for which MAFLD is thought to be of metabolic origin could be exposed, the bottom line relies on the role of IR as an initiator and perpetuator of this disease. There is a reciprocal role in MAFLD development and IR as well as serum glucose concentrations, where increased circulating glucose and insulin result in increased de novo lipogenesis by sterol regulatory element-binding protein-1c induced lipogenic enzyme stimulation; therefore, increased endogenous production of triglycerides. The same effect is achieved through impaired suppression of adipose tissue (AT) lipolysis in insulin-resistant states, increasing fatty acid influx into the liver. The complementary reciprocal situation occurs when liver steatosis alters hepatokine secretion, modifying fatty acid metabolism as well as IR in a variety of tissues, including skeletal muscle, AT, and the liver. The aim of this review is to discuss the importance of IR and AT interactions in metabolic altered states as perhaps the most important factor in MAFLD pathogenesis.

Whole Grain Proso Millet (Panicum miliaceum L.) Attenuates Hyperglycemia in Type 2 Diabetic Mice: Involvement of miRNA Profile

This work aimed to investigate the hypoglycemic effects and underlying mechanism of whole grain proso millet (Panicum miliaceum L.; WPM) on type 2 diabetes mellitus (T2DM). The results showed that WPM supplementation significantly reduced fasting blood glucose (FBG) and serum lipid levels in T2DM mice induced by a high-fat diet (HFD) combined with streptozotocin (STZ), with improved glucose tolerance, liver and kidney injury, and insulin resistance. In addition, WPM significantly inhibited the expression of gluconeogenesis-related genes G6pase, Pepck, Foxo1, and Pgc-1α. Further study by miRNA high-throughput sequencing revealed that WPM supplementation mainly altered the liver miRNA expression profile of T2DM mice by increasing the expression of miR-144-3p_R-1 and miR-423-5p, reducing the expression of miR-22-5p_R-1 and miR-30a-3p. GO and KEGG analyses showed that the target genes of these miRNAs were mainly enriched in the PI3K/AKT signaling pathway. WPM supplementation significantly increased the level of PI3K, p-AKT, and GSK3β in the liver of T2DM mice. Taken together, WPM exerts antidiabetic effects by improving the miRNA profile and activating the PI3K/AKT signaling pathway to inhibit gluconeogenesis. This study implies that PM can act as a dietary supplement to attenuate T2DM.

Wen-Shen-Jian-Pi-Hua-Tan decoction protects against early obesity-related glomerulopathy by improving renal bile acid composition and suppressing lipogenesis, inflammation, and fibrosis

BACKGROUND

Obesity is an independent predictor of chronic kidney disease (CKD) development and may directly lead to kidney lesions such as obesity-related glomerulopathy (ORG) which might play a vital pathogenic role in obese patients with CKD. Wen-Shen-Jian-Pi-Hua-Tan decoction (WSHT) has been clinically used for the treatment of obesity and obesity-related metabolic diseases for years. However, the renoprotective effects and potential mechanism of action of WSHT against ORG remain unknown.

PURPOSE

This study aimed to explore the potential effect of WSHT on ORG and reveal its mechanisms in high-fat diet (HFD)-induced obese rats.

METHODS

An animal model of early stage ORG was established using HFD-induced obese rats. After treatment with WSHT for 6 weeks, an integrated metabolomics and molecular biology strategy was utilized to illustrate the effects and mechanism of WSHT on ORG. First, UPLC-ESI-MS/MS-based targeted metabolomics was used to analyze renal bile acid (BA) levels. Biochemical, histological, and immunofluorescence assays; electron microscopy; and western blotting were performed to evaluate the efficacy of WSHT against ORG and its underlying mechanisms in vivo.

RESULTS

Our results showed that an HFD led to hyperlipidemia, proteinuria, renal lipid deposition, effacement of podocyte foot processes, and increased expression of proinflammatory factors and profibrotic growth factors in ORG rats. In addition, an HFD decreased the levels of renal BAs such as cholic acid, chenodeoxycholic acid, and lithocholic acid. After 6 weeks of treatment, WSHT markedly attenuated dyslipidemia and reduced body, kidney and epididymal fat weights in ORG rats. WSHT also significantly increased BA levels, suggesting that it altered BA composition; the effects of BAs are closely associated with farnesoid X receptor (FXR) activation. WSHT alleviated fat accumulation, podocyte loss and proteinuria, and reduced the expression of proinflammatory cytokines and profibrotic growth factors in the kidneys of ORG rats. Finally, WSHT remarkably upregulated the renal expression of FXR and salt-induced kinase 1 and blocked the renal expression of sterol regulatory element-binding protein-1c and its target genes.

CONCLUSION

WSHT attenuated early renal lesions in ORG rats by improving renal BA composition and suppressing lipogenesis, inflammation and fibrosis. This study develops a new way to alleviate obesity-induced renal damages.

Metabolic Syndrome and Its Association with Nonalcoholic Steatohepatitis

The relationship between insulin resistance, metabolic syndrome (MetS), and nonalcoholic fatty liver disease (NAFLD) is complicated. Although insulin resistance is almost universal in people with NAFLD and MetS, NAFLD may be present without features of MetS and vice versa. While NAFLD has a strong correlation with cardiometabolic risk factors, these are not intrinsic components of this condition. Taken together, our knowledge gaps call for caution regarding the common assertion that NAFLD is the hepatic manifestation of the MetS, and for defining NAFLD in broad terms as a "metabolic dysfunction" based on a diverse and poorly understood constellation of cardiometabolic features.

Genetic deletion of phosphodiesterase 4D in the liver improves kidney damage in high-fat fed mice: liver-kidney crosstalk

A growing body of epidemiological evidence suggests that nonalcoholic fatty liver disease (NAFLD) is an independent risk factor for chronic kidney disease (CKD), but the regulatory mechanism linking NAFLD and CKD remains unclear. Our previous studies have shown that overexpression of PDE4D in mouse liver is sufficient for NAFLD, but little is known about its role in kidney injury. Here, liver-specific PDE4D conditional knockout (LKO) mice, adeno-associated virus 8 (AAV8)-mediated gene transfer of PDE4D and the PDE4 inhibitor roflumilast were used to assess the involvement of hepatic PDE4D in NAFLD-associated renal injury. We found that mice fed a high-fat diet (HFD) for 16 weeks developed hepatic steatosis and kidney injury, with an associated increase in hepatic PDE4D but no changes in renal PDE4D. Furthermore, liver-specific knockout of PDE4D or pharmacological inhibition of PDE4 with roflumilast ameliorated hepatic steatosis and kidney injury in HFD-fed diabetic mice. Correspondingly, overexpression of hepatic PDE4D resulted in significant renal damage. Mechanistically, highly expressed PDE4D in fatty liver promoted the production and secretion of TGF-β1 into blood, which triggered kidney injury by activating SMADs and subsequent collagen deposition. Our findings revealed PDE4D might act as a critical mediator between NAFLD and associated kidney injury and indicated PDE4 inhibitor roflumilast as a potential therapeutic strategy for NAFLD-associated CKD.

Mouse strain-dependent variation in metabolic associated fatty liver disease (MAFLD): a comprehensive resource tool for pre-clinical studies

Non-alcoholic steatohepatitis (NASH), characterized as the joint presence of steatosis, hepatocellular ballooning and lobular inflammation, and liver fibrosis are strong contributors to liver-related and overall mortality. Despite the high global prevalence of NASH and the substantial healthcare burden, there are currently no FDA-approved therapies for preventing or reversing NASH and/or liver fibrosis. Importantly, despite nearly 200 pharmacotherapies in different phases of pre-clinical and clinical assessment, most therapeutic approaches that succeed from pre-clinical rodent models to the clinical stage fail in subsequent Phase I-III trials. In this respect, one major weakness is the lack of adequate mouse models of NASH that also show metabolic comorbidities commonly observed in NASH patients, including obesity, type 2 diabetes and dyslipidaemia. This study provides an in-depth comparison of NASH pathology and deep metabolic profiling in eight common inbred mouse strains (A/J, BALB/c, C3H/HeJ, C57BL/6J, CBA/CaH, DBA/2J, FVB/N and NOD/ShiLtJ) fed a western-style diet enriched in fat, sucrose, fructose and cholesterol for eight months. Combined analysis of histopathology and hepatic lipid metabolism, as well as measures of obesity, glycaemic control and insulin sensitivity, dyslipidaemia, adipose tissue lipolysis, systemic inflammation and whole-body energy metabolism points to the FVB/N mouse strain as the most adequate diet-induced mouse model for the recapitulation of metabolic (dysfunction) associated fatty liver disease (MAFLD) and NASH. With efforts in the pharmaceutical industry now focussed on developing multi-faceted therapies; that is, therapies that improve NASH and/or liver fibrosis, and concomitantly treat other metabolic comorbidities, this mouse model is ideally suited for such pre-clinical use.

Metabolic-associated fatty liver disease increases the risk of end-stage renal disease in patients with biopsy-confirmed diabetic nephropathy: a propensity-matched cohort study

AIMS

To investigate the relationship between metabolic-associated fatty liver disease (MAFLD) and end-stage renal disease (ESRD) in patients with biopsy-confirmed diabetic nephropathy (DN).

METHODS

A total of 316 participants with biopsy-confirmed DN between January 2008 and December 2019 were retrospectively assessed. Kaplan-Meier curve and Cox proportional hazard models were used to compare the risk of incident ESRD in 50 patients with MAFLD and 50 patients without MAFLD, after using propensity score matching (PSM) to address the imbalances of sex, age, baseline-estimated glomerular filtration rate, serum albumin, 24-h urine protein, hemoglobin and systolic blood pressure.

RESULTS

During the median follow-up period of 3 years, there were 19 ESRD outcome events (19%) in PSM cohort. Kaplan-Meier curve analysis suggested that renal survival significantly deteriorated in patients with MAFLD versus those without MAFLD (p = 0.021). Additionally, the hazard ratios (95% confidence interval) of MAFLD were 3.12 (1.09-8.95, p = 0.035), 3.36 (1.09-10.43, p = 0.036), 3.66 (1.22-10.98, p = 0.021), 4.25 (1.34-13.45, p = 0.014), 3.11 (1.08-8.96, p = 0.035) and 5.84 (1.94-18.5, p = 0.003) after adjustment for six models, including demographic, clinical and pathological characteristics as well as medication use at the time of renal biopsy, respectively. Besides, patients with higher liver fibrosis score had a greater possibility of ESRD, comparing to those with lower liver fibrosis score (p = 0.002).

CONCLUSIONS

MAFLD increases the risk of incident ESRD in patients with biopsy-proven DN. Further research is needed to determine whether treatment targeting MAFLD improves the prognosis of DN.

MAFLD and NAFLD in the prediction of incident chronic kidney disease

Whether metabolic dysfunction-associated fatty liver disease (MAFLD) can replace nonalcoholic fatty liver disease (NAFLD) is under debate. This study evaluated which definition better predicted incident chronic kidney disease (CKD). This was a 5.3-year (range, 2.8-8.3) retrospective cohort study of 21,713 adults who underwent at least two serial health examinations. Cox analyses were used to compare the risk of incident CKD among non-fatty liver disease (FLD) without metabolic dysregulation (MD; reference), non-FLD with MD, MAFLD-only, NAFLD-only, or both-FLD groups. Non-FLD with MD group (hazard ratio [HR] 1.23, 95% confidence interval [CI] 1.00-1.53), both-FLD group (HR 1.50, 95% CI 1.19-1.89), and MAFLD-only group (HR 1.97, 95% CI 1.49-2.60), but not NAFLD-only group (HR 1.06, 95% CI 0.63-1.79) demonstrated an increased risk of CKD. The increased risk of CKD was significant in MAFLD subgroups with overweight/obesity (HR 2.94, 95% CI 1.91-4.55), diabetes (HR 2.20, 95% CI 1.67-2.90), MD only (HR 1.50, 95% CI 1.19-1.89), excessive alcohol consumption (HR 2.71, 95% CI 2.11-3.47), and viral hepatitis (HR 2.38, 95% CI 1.48-3.84). The switch from NAFLD to MAFLD criteria may identify a greater number of individuals at CKD risk. The association was also significant in MAFLD patients with excessive alcohol consumption or viral hepatitis.

A Comprehensive Weighted Gene Co-expression Network Analysis Uncovers Potential Targets in Diabetic Kidney Disease

Background and Objectives

Diabetic kidney disease (DKD) is one of the most common microvascular complications of diabetes. It has always been difficult to explore novel biomarkers and therapeutic targets of DKD. We aimed to identify new biomarkers and further explore their functions in DKD.

Methods

The weighted gene co-expression network analysis (WGCNA) method was used to analyze the expression profile data of DKD, obtain key modules related to the clinical traits of DKD, and perform gene enrichment analysis. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to verify the mRNA expression of the hub genes in DKD. Spearman's correlation coefficients were used to determine the relationship between gene expression and clinical indicators.

Results

Fifteen gene modules were obtained via WGCNA analysis, among which the green module had the most significant correlation with DKD. Gene enrichment analysis revealed that the genes in this module were mainly involved in sugar and lipid metabolism, regulation of small guanosine triphosphatase (GTPase) mediated signal transduction, G protein-coupled receptor signaling pathway, peroxisome proliferator-activated receptor (PPAR) molecular signaling pathway, Rho protein signal transduction, and oxidoreductase activity. The qRT-PCR results showed that the relative expression of nuclear pore complex-interacting protein family member A2 (NPIPA2) and ankyrin repeat domain 36 (ANKRD36) was notably increased in DKD compared to the control. NPIPA2 was positively correlated with the urine albumin/creatinine ratio (ACR) and serum creatinine (Scr) but negatively correlated with albumin (ALB) and hemoglobin (Hb) levels. ANKRD36 was positively correlated with the triglyceride (TG) level and white blood cell (WBC) count.

Conclusion

NPIPA2 expression is closely related to the disease condition of DKD, whereas ANKRD36 may be involved in the progression of DKD through lipid metabolism and inflammation, providing an experimental basis to further explore the pathogenesis of DKD.

Liver steatosis and fibrosis markers' association with cardiovascular and renal damage in Japanese adults: the TMM BirThree cohort study

INTRODUCTION AND OBJECTIVES

Patients with non-alcoholic fatty liver disease (NAFLD) are at risk for cardiovascular and chronic kidney diseases. Liver steatosis and fibrosis were assessed using the fatty liver index and fibrosis-4 index, respectively. This study aimed to examine the association between these two parameters in patients with atherosclerosis and chronic kidney disease.

MATERIALS AND METHODS

The two parameters were calculated for 11,867 adults who participated in the Tohoku Medical Megabank Project Birth and Three-Generation Cohort Study. Intima-media thickness and estimated glomerular filtration rate were also measured. Logistic regression models were used to estimate the odds ratios (OR).

RESULTS

Overall, 4257 (35.9%) and 4733 (39.9%) participants had a higher probability of liver steatosis and fibrosis, respectively. The adjusted OR of higher fatty liver index compared to lower fatty liver index for atherosclerosis and chronic kidney disease were 0.98 (95% confidence interval [CI], 0.77-1.24) and 1.79 (95% CI, 1.19-2.69), and those of higher FIB-4 compared to lower FIB-4 were 1.03 (95% CI, 0.82-1.30) and 0.79 (95% CI, 0.52-1.19) for atherosclerosis and chronic kidney disease, respectively.

CONCLUSIONS

A higher FLI was associated with CKD independent of other risk factors. Further research is required to identify the causal relationship between liver fat accumulation and CKD.

Heart Uptake of [18F]Fluoro-4-Thia-Oleate in a Non-Alcoholic Fatty Liver Disease Mouse Model

The world-wide high incidence of non-alcoholic fatty liver disease (NAFLD) is of concern for its progression to insulin resistance, steatohepatitis and cardiovascular disease (CVD). The increased uptake of fatty acids in critical organs plays a major role in NAFLD progression. Male Ceacam1−/− mice that develop NAFLD, insulin resistance and CVD on normal chow are a potential model for studying the dysregulation of fatty acid uptake. [18F]fluoro-4-thia-oleate ([18F]FTO) was chosen as a fatty acid reporter because of its higher uptake and retention in the heart in an animal model of CVD. Male wild-type (WT) or Ceacam1−/− mice fasted 4−6 h were administered [18F]FTO i.v., and dynamic PET scans were conducted in an MR/PET small animal imaging system along with terminal tissue biodistributions. Quantitative heart image analysis revealed significantly higher uptake at 35 min in Ceacam1−/− (6.0 ± 1.0% ID/cc) vs. WT (3.9 ± 0.6% ID/cc) mice (p = 0.006). Ex vivo heart uptake/retention (% ID/organ) was 2.82 ± 0.45 for Ceacam1−/− mice vs. 1.66 ± 0.45 for WT mice (p < 0.01). Higher kidney and pancreas uptake/retention in Ceacam1−/− was also evident, and the excretion of [18F]FTO into the duodenum was observed for both WT and Ceacam1−/− mice starting at 10 min. This study suggests that the administration of [18F]FTO as a marker of fatty acid uptake and retention may be an important tool in analyzing the effect of NAFLD on lipid dysregulation in the heart.

A comprehensive weighted gene co-expression network analysis uncovers potential targets in diabetic kidney disease

Background and Objectives

Diabetic kidney disease (DKD) is one of the most common microvascular complications of diabetes. It has always been difficult to explore novel biomarkers and therapeutic targets of DKD. We aimed to identify new biomarkers and further explore their functions in DKD.

Methods

The weighted gene co-expression network analysis (WGCNA) method was used to analyze the expression profile data of DKD, obtain key modules related to the clinical traits of DKD, and perform gene enrichment analysis. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to verify the mRNA expression of the hub genes in DKD. Spearman’s correlation coefficients were used to determine the relationship between gene expression and clinical indicators.

Results

Fifteen gene modules were obtained via WGCNA analysis, among which the green module had the most significant correlation with DKD. Gene enrichment analysis revealed that the genes in this module were mainly involved in sugar and lipid metabolism, regulation of small guanosine triphosphatase (GTPase) mediated signal transduction, G protein-coupled receptor signaling pathway, peroxisome proliferator-activated receptor (PPAR) molecular signaling pathway, Rho protein signal transduction, and oxidoreductase activity. The qRT-PCR results showed that the relative expression of nuclear pore complex-interacting protein family member A2 (NPIPA2) and ankyrin repeat domain 36 (ANKRD36) was notably increased in DKD compared to the control. NPIPA2 was positively correlated with the urine albumin/creatinine ratio (ACR) and serum creatinine (Scr) but negatively correlated with albumin (ALB) and hemoglobin (Hb) levels. ANKRD36 was positively correlated with the triglyceride (TG) level and white blood cell (WBC) count.

Conclusion

NPIPA2 expression is closely related to the disease condition of DKD, whereas ANKRD36 may be involved in the progression of DKD through lipid metabolism and inflammation, providing an experimental basis to further explore the pathogenesis of DKD.

Crosstalk between kidney and liver in non-alcoholic fatty liver disease: mechanisms and therapeutic approaches

Liver and kidney are vital organs that maintain homeostasis and injury to either of them triggers pathogenic pathways affecting the other. For example, non-alcoholic fatty liver disease (NAFLD) promotes the progression of chronic kidney disease (CKD), vice versa acute kidney injury (AKI) endorses the induction and progression of liver dysfunction. Progress in clinical and basic research suggest a role of excessive fructose intake, insulin resistance, inflammatory cytokines production, activation of the renin-angiotensin system, redox imbalance, and their impact on epigenetic regulation of gene expression in this context. Recent developments in experimental and clinical research have identified several biochemical and molecular pathways for AKI-liver interaction, including altered liver enzymes profile, metabolic acidosis, oxidative stress, activation of inflammatory and regulated cell death pathways. This review focuses on the current preclinical and clinical findings on kidney-liver crosstalk in NAFLD-CKD and AKI-liver dysfunction settings and highlights potential molecular mechanisms and therapeutic targets.

Association of serum creatinine with hepatic steatosis and fibrosis: a cross-sectional study

Background

Recent studies have shown that chronic kidney disease (CKD) prevalence is significantly higher in patients with hepatic steatosis (HS); however, it remains unclear whether HS is associated with serum creatinine (SCr). We aimed to explore the association between SCr levels and HS in a Chinese population.

Methods

We performed a cross-sectional study among 56,569 Chinese individuals. SCr level, other clinical and laboratory parameters, abdominal ultrasound and noninvasive fibrosis scores were extracted, and the fibrosis 4 score (FIB-4) was calculated.

Results

A total of 27.1% of the subjects had HS. After 1:1 propensity score matching (PSM) according to sex and age, we included 13,301 subjects with HS and 13,301 subjects without HS. SCr levels were significantly higher in the HS group than in the non-HS group [73.19 ± 15.14(μmoI/L) vs. 71.75 ± 17.49(μmoI/L), p < 0.001]. Univariate and multivariate regression analyses showed a positive association between SCr and the prevalence of HS. Stepwise regression analysis showed that the association between SCr and HS was independent of other metabolic syndrome components. The prevalence of HS increased significantly with increasing SCr levels. Metabolism-related indicators and liver enzymes were significantly higher in the HS group than in the non-HS group; furthermore, these parameters increased with increasing SCr levels. FIB-4 was significantly higher in the HS group than in the non-HS group but did not show an increasing trend with increasing SCr levels.

Conclusions

Our results showed an independent association between SCr level and HS risk in a Chinese population.

Increased Renal Expression of Complement Components in Patients With Liver Diseases: Nonalcoholic Steatohepatitis, Alcohol-Associated, Viral Hepatitis, and Alcohol-Viral Combination

Inflammatory liver diseases, including nonalcoholic steatohepatitis (NASH), alcohol-associated liver disease (ALD), hepatitis C virus (HCV), and ALD/HCV, account for nearly 2 million deaths annually. Despite increasing evidence that liver dysfunction impacts renal physiology, there is limited supportive clinical information, due to limited diagnosis of liver disease, complexity in liver disease etiology, and inadequacy of renal function tests. Human kidney biopsies with liver and renal pathology were obtained from patients with nonalcoholic fatty liver disease (NAFLD), NASH, ALD, HCV, and ALD/HCV (n = 5-7). Each liver disease showed renal pathology with at least 50% interstitial nephritis, 50% interstitial fibrosis, and renal dysfunction by estimated glomerular filtration rate (NAFLD 36.7 ± 21.4; NASH 32.7 ± 15.0; ALD 16.0 ± 11.0; HCV 27.6 ± 11.5; ALD/HCV 21.0 ± 11.2 ml/min/1.73 m2). Transcriptomic analysis identified 55 genes with expression changes in a conserved direction in response to liver disease. Considering association with immune regulation, protein levels of alpha-2-macroglobulin, clusterin, complement C1q C chain (C1QC), CD163, and joining chain of multimeric IgA and IgM (JCHAIN) were further quantified by LC-MS/MS. C1QC demonstrated an increase in NASH, ALD, HCV, and ALD/HCV (42.9 ± 16.6; 38.8 ± 18.4; 39.0 ± 13.5; 40.1 ± 20.1 pmol/mg protein) relative to control (19.2 ± 10.4 pmol/mg protein; p ≤ 0.08). Renal expression changes identified in inflammatory liver diseases with interstitial pathology suggest the pathogenesis of liver associated renal dysfunction. This unique cohort overcomes diagnostic discrepancies and sample availability to provide insight for mechanistic investigations on the impact of liver dysfunction on renal physiology.

Nonalcoholic Fatty Liver Disease and Cardiovascular Disease: a Review of Shared Cardiometabolic Risk Factors

The prevalence of nonalcoholic fatty liver disease (NAFLD) is rising. NAFLD/nonalcoholic steatohepatitis (NASH) is associated not only with hepatic morbidity and mortality but also with an increased cardiovascular risk. NAFLD and cardiovascular disease (CVD) share several risk factors, such as obesity, metabolic syndrome, hypertension, dyslipidemia, type 2 diabetes, and chronic kidney disease. This review summarizes the evidence linking cardiometabolic risk factors and NAFLD in the context of risk for CVD. The cause of NAFLD/NASH is complex, involving a range of factors from genetics to lifestyle and energy balance. Genetically driven high liver fat content does not appear to be causally associated with increased CVD risk. In contrast, metabolic dysfunction not only predisposes to liver pathology but also leads to a significantly higher CVD risk. Given that NAFLD pathophysiology is influenced by multiple factors, each patient is unique as to their risk of developing CVD and liver pathology. At the same time, the rising burden of NAFLD/NASH is closely linked with the global increase in metabolic disorders, including obesity and type 2 diabetes. Therefore, both personalized therapeutic approaches that recognize individual pathophysiology, as well as public health policies that address the root causes of cardiometabolic risk factors for NAFLD may be needed to effectively address the NAFLD/NASH epidemic.

Obesity-related glomerulopathy: Current approaches and future perspectives

Obesity-related glomerulopathy (ORG) is a silent comorbidity which is increasing in incidence as the obesity epidemic escalates. ORG is associated with serious health consequences including chronic kidney disease, end-stage renal disease (ESRD), and increased mortality. Although the pathogenic mechanisms involved in the development of ORG are not fully understood, glomerular hemodynamic changes, renin-angiotensin-aldosterone system (RAAS) overactivation, insulin-resistance, inflammation and ectopic lipid accumulation seem to play a major role. Despite albuminuria being commonly used for the non-invasive evaluation of ORG, promising biomarkers of early kidney injury that are emerging, as well as new approaches with proteomics and metabolomics, might permit an earlier diagnosis of this disease. In addition, the assessment of ectopic kidney fat by renal imaging could be a useful tool to detect and evaluate the progression of ORG. Weight loss interventions appear to be effective in ORG, although large-scale trials are needed. RAAS blockade has a renoprotective effect in patients with ORG, but even so, a significant proportion of patients with ORG will eventually progress to ESRD despite therapeutic efforts. It is noteworthy that certain antidiabetic agents such as sodium-glucose cotransporter 2 inhibitors (SGLT2i) or glucagon-like peptide-1 receptor agonists (GLP-1 RAs) could be useful in the treatment of ORG through different pleiotropic effects. In this article, we review current approaches and future perspectives in the care and treatment of ORG.

Efficacy and safety of cotadutide, a dual glucagon-like peptide-1 and glucagon receptor agonist, in a randomized phase 2a study of patients with type 2 diabetes and chronic kidney disease

AIM

To assess the efficacy, safety and tolerability of cotadutide in patients with type 2 diabetes mellitus and chronic kidney disease.

MATERIALS AND METHODS

In this phase 2a study (NCT03550378), patients with body mass index 25-45 kg/m² , estimated glomerular filtration rate 30-59 ml/min/1.73 m² and type 2 diabetes [glycated haemoglobin 6.5-10.5% (48-91 mmol/mol)] controlled with insulin and/or oral therapy combination, were randomized 1:1 to once-daily subcutaneous cotadutide (50-300 μg) or placebo for 32 days. The primary endpoint was plasma glucose concentration assessed using a mixed-meal tolerance test.

RESULTS

Participants receiving cotadutide (n = 21) had significant reductions in the mixed-meal tolerance test area under the glucose concentration-time curve (-26.71% vs. +3.68%, p < .001), more time in target glucose range on continuous glucose monitoring (+14.79% vs. -21.23%, p = .001) and significant reductions in absolute bodyweight (-3.41 kg vs. -0.13 kg, p < .001) versus placebo (n = 20). In patients with baseline micro- or macroalbuminuria (n = 18), urinary albumin-to-creatinine ratios decreased by 51% at day 32 with cotadutide versus placebo (p = .0504). No statistically significant difference was observed in mean change in estimated glomerular filtration rate between treatments. Mild/moderate adverse events occurred in 71.4% of participants receiving cotadutide and 35.0% receiving placebo.

CONCLUSIONS

We established the efficacy of cotadutide in this patient population, with significantly improved postprandial glucose control and reduced bodyweight versus placebo. Reductions in urinary albumin-to-creatinine ratios suggest potential benefits of cotadutide on kidney function, supporting further evaluation in larger, longer-term clinical trials.

Paricalcitol Attenuates Metabolic Syndrome-Associated Heart Failure through Enhanced Mitochondrial Fusion

Objectives

Transition from cardiac hypertrophy to failure involves adverse metabolic reprogramming involving mitochondrial dysfunction. We have earlier shown that vitamin D deficiency induces heart failure, at least in part, through insulin resistance. However, whether activation of vitamin D receptor (VDR) can attenuate heart failure and underlying metabolic phenotype requires investigation. Thus, we aimed to assess the cardioprotective potential of paricalcitol, a vitamin D receptor-activator, against cardiac hypertrophy and failure in high-fat high-fructose-fed rats.

Methods

Male Sprague Dawley rats were fed control (Con) or high-fat high-fructose (HFHFrD) diet for 20 weeks. After 12 weeks, rats from HFHFrD group were divided into the following: HFHFrD, HFHFrD+P (paricalcitol i.p. 0.08 μg/kg/day) and HFHFrD+E (enalapril maleate i.p. 10 mg/kg/day). Intraperitoneal glucose tolerance test, blood pressure measurement, and 2D echocardiography were performed. Cardiac fibrosis was assessed by Masson's trichrome staining of paraffin-embedded heart sections. Mitochondrial DNA and proteins, and citrate synthase activity were measured in rat hearts. VDR was silenced in H9c2 cardiomyoblasts, and immunoblotting was performed.

Results

Paricalcitol improved glucose tolerance, serum lipid profile, and blood pressure in high-fat high-fructose-fed rats. Paricalcitol reduced cardiac wall thickness and increased ejection fraction in high-fat high-fructose-fed rats but had no effect on perivascular fibrosis. PGC1-α was upregulated in the HFHFrD+P group compared to the HFHFrD group, but there was no significant difference in mitochondrial content. Citrate synthase activity was significantly higher in the HFHFrD+P group compared to the HFHFrD group. Rat hearts of the HFHFrD+P group had significantly higher expression of mitofusins. H9c2 cells with VDR knockdown showed significantly lower expression of Mfn2. Improvement in the HFHFrD+P group was comparable with that in the HFHFrD+E group.

Conclusions

Paricalcitol reverses cardiac dysfunction in rats with metabolic syndrome by enhancing mitochondrial fusion. We demonstrate repurposing potential of the drug currently used in end-stage kidney disease.

The Roles of Fatty Acids and Apolipoproteins in the Kidneys

The kidneys are organs that require energy from the metabolism of fatty acids and glucose; several studies have shown that the kidneys are metabolically active tissues with an estimated energy requirement similar to that of the heart. The kidneys may regulate the normal and pathological function of circulating lipids in the body, and their glomerular filtration barrier prevents large molecules or large lipoprotein particles from being filtered into pre-urine. Given the permeable nature of the kidneys, renal lipid metabolism plays an important role in affecting the rest of the body and the kidneys. Lipid metabolism in the kidneys is important because of the exchange of free fatty acids and apolipoproteins from the peripheral circulation. Apolipoproteins have important roles in the transport and metabolism of lipids within the glomeruli and renal tubules. Indeed, evidence indicates that apolipoproteins have multiple functions in regulating lipid import, transport, synthesis, storage, oxidation and export, and they are important for normal physiological function. Apolipoproteins are also risk factors for several renal diseases; for example, apolipoprotein L polymorphisms induce kidney diseases. Furthermore, renal apolipoprotein gene expression is substantially regulated under various physiological and disease conditions. This review is aimed at describing recent clinical and basic studies on the major roles and functions of apolipoproteins in the kidneys.

The Negative Association Between NAFLD Severity and CKD in a Non-Diabetic Gouty Population

Nonalcoholic fatty liver disease (NAFLD) and chronic kidney disease (CKD) share common pathogenic mechanisms and risk factors. We aim to evaluate the association between NAFLD and CKD in a non-diabetic gouty population. The retrospective cross sectional study was performed on 1049 non-diabetic gouty participants, who were hospitalized between 2014 and 2020, across 4 districts in Shandong, China. Demographic and clinical characteristics of the study population were collected. The odds ratios (OR) and corresponding 95% confidence intervals (CI) about the NAFLD severity determined by ultrasonography were obtained by multiple logistic regression analysis. An unexpectedly inverse relationship was found between NAFLD severity and the risk of CKD in people with gout. Multivariate logistic regression analysis demonstrated that a higher degree of NAFLD severity is independently associated with a lower risk of CKD in people with gout, after adjusted for age, sex, smoking, gout duration, and metabolic risk factors including obesity, hypertension, hyperglycemia, hyperuricemia, and dyslipidemia, with OR 0.392 (95% CI 0.248-0.619, p<0.001), 0.379 (95% CI 0.233-0.616, p<0.001) and 0.148 (95% CI 0.043-0.512, p=0.003) in participants with mild, moderate, and severe NAFLD, respectively, compared to those without NAFLD. We also observed a weakened association of serum uric acid (SUA) with metabolic risk factors and NAFLD under circumstances of CKD in people with gout (r=-0.054, p=0.466). In conclusion, the presence and severity of NAFLD were negatively associated with the risk of CKD in the non-diabetic gouty population.

The Interplay Between Nonalcoholic Fatty Liver Disease and Kidney Disease

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease worldwide, involving approximately 25% of the general population and increasing in prevalence in patient populations afflicted with metabolic syndrome and type 2 diabetes. This article discusses the complex interplay between NAFLD and chronic kidney disease (CKD), as well as the underlying pathogenesis and mechanisms through which NAFLD and CKD are linked. Exploration of these sophisticated relationships and causative factors is essential to accurately assessing kidney function in patients with NAFLD, recommending pharmacologic treatment of disease, and identifying favorable avenues for future investigation.

Advanced liver fibrosis measured by transient elastography predicts chronic kidney disease development in individuals with non-alcoholic fatty liver disease

AIMS/HYPOTHESIS

Non-alcoholic fatty liver disease (NAFLD) and chronic kidney disease (CKD) are progressive chronic conditions that share important cardiometabolic risk factors and pathogenic mechanisms. We investigated the association between liver fibrosis measured by transient elastography (TE) and the risk of incident CKD in individuals with NAFLD.

METHODS

A total of 5983 participants with NAFLD (defined as controlled attenuation parameter >222 dB/m) but without CKD who underwent TE between March 2012 and August 2018 were selected. The primary outcome was incident CKD, defined as the occurrence of eGFR <60 ml min^-1 [1.73 m]^-2 or proteinuria (≥1+ on dipstick test) on two consecutive measurements during follow-up. The secondary outcome was a 25% decline in eGFR measured on two consecutive visits.

RESULTS

The mean age was 51.8 years and 3756 (62.8%) participants were male. During 17,801 person-years of follow-up (mean follow-up of 3.0 years), 62 participants (1.0%) developed incident CKD. When stratified into TE-defined fibrosis stages (F0-F4), multivariable Cox models revealed that risk of incident CKD was 5.40-fold (95% CI 2.46, 11.84; p < 0.001) higher in the F3/F4 group (≥9.5 kPa) than in the F0 group (<5.5 kPa). During 17,577 person-years of follow-up (mean follow-up of 3.0 years), 201 participants (3.4%) experienced the secondary outcome, for which the F3/F4 group had a 3.22-fold higher risk (95% CI 1.96, 5.28; p < 0.001) than the F0 group.

CONCLUSIONS/INTERPRETATION

In this large cohort of individuals with NAFLD but without baseline CKD, advanced liver fibrosis measured by TE was significantly associated with a higher risk of incident CKD.

Glomerular Biomechanical Stress and Lipid Mediators during Cellular Changes Leading to Chronic Kidney Disease

Hyperfiltration is an important underlying cause of glomerular dysfunction associated with several systemic and intrinsic glomerular conditions leading to chronic kidney disease (CKD). These include obesity, diabetes, hypertension, focal segmental glomerulosclerosis (FSGS), congenital abnormalities and reduced renal mass (low nephron number). Hyperfiltration-associated biomechanical forces directly impact the cell membrane, generating tensile and fluid flow shear stresses in multiple segments of the nephron. Ongoing research suggests these biomechanical forces as the initial mediators of hyperfiltration-induced deterioration of podocyte structure and function leading to their detachment and irreplaceable loss from the glomerular filtration barrier. Membrane lipid-derived polyunsaturated fatty acids (PUFA) and their metabolites are potent transducers of biomechanical stress from the cell surface to intracellular compartments. Omega-6 and ω-3 long-chain PUFA from membrane phospholipids generate many versatile and autacoid oxylipins that modulate pro-inflammatory as well as anti-inflammatory autocrine and paracrine signaling. We advance the idea that lipid signaling molecules, related enzymes, metabolites and receptors are not just mediators of cellular stress but also potential targets for developing novel interventions. With the growing emphasis on lifestyle changes for wellness, dietary fatty acids are potential adjunct-therapeutics to minimize/treat hyperfiltration-induced progressive glomerular damage and CKD.

Serum creatinine levels and risk of nonalcohol fatty liver disease in a middle-aged and older Chinese population: A cross-sectional analysis

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is now regarded as the hepatic manifestation of metabolic syndrome (MetS). Recent research has suggested that serum creatinine (SCr) may be an indicator of MetS and its related diseases. We aimed to investigate the association between SCr and NAFLD in Chinese adults.

METHODS

A cross-sectional sample of 8862 subjects aged 40 years or older (40-73 years) from China were analysed in this study. The anthropometric measurements, laboratory tests, and hepatic ultrasonography were conducted. NAFLD presence was defined by hepatic ultrasound in the absence of other liver diseases.

RESULTS

NAFLD subjects had higher SCr than those without NAFLD (66.8 μmol/L vs. 65.6 μmol/L, p < 0.001). Moreover, SCr levels were correlated with alanine aminotransferase (β = 0.099, p < 0.001), aspartate aminotransferase (β = 0.135, p < 0.001), γ-glutamyltransferase (β = 0.039, p < 0.001), and insulin resistance (β = 0.027, p = 0.014) after adjusted for potential covariates. In the multivariable-adjusted logistic regression analyses, compared to the first SCr quintile, the odds ratio for NAFLD was 1.35 (95% confidence interval 1.14-1.60, p < 0.001) for the fifth quintile after adjusting multiple measured confounders.

CONCLUSION

SCr concentration is independently associated with NAFLD in a middle aged and older Chinese population. Elevated SCr levels, even within normal ranges, were associated with higher risk of NAFLD.

Integrated analysis of potential gene crosstalk between non-alcoholic fatty liver disease and diabetic nephropathy

BACKGROUND

Growing evidence indicates that non-alcoholic fatty liver disease (NAFLD) is related to the occurrence and development of diabetic nephropathy (DN). This bioinformatics study aimed to explore optimal crosstalk genes and related pathways between NAFLD and DN.

METHODS

Gene expression profiles were downloaded from Gene Expression Omnibus. CIBERSORT algorithm was employed to analyze the similarity of infiltrating immunocytes between the two diseases. Protein-protein interaction (PPI) co-expression network and functional enrichment analysis were conducted based on the identification of common differentially expressed genes (DEGs). Least absolute shrinkage and selection operator (LASSO) regression and Boruta algorithm were implemented to initially screen crosstalk genes. Machine learning models, including support vector machine, random forest model, and generalized linear model, were utilized to further identify the optimal crosstalk genes between DN and NAFLD. An integrated network containing crosstalk genes, transcription factors, and associated pathways was developed.

RESULTS

Four gene expression datasets, including GSE66676 and GSE48452 for NAFLD and GSE30122 and GSE1009 for DN, were involved in this study. There were 80 common DEGs between the two diseases in total. The PPI network built with the 80 common genes included 77 nodes and 83 edges. Ten optimal crosstalk genes were selected by LASSO regression and Boruta algorithm, including CD36, WIPI1, CBX7, FCN1, SLC35D2, CP, ZDHHC3, PTPN3, LPL, and SPP1. Among these genes, LPL and SPP1 were the most significant according to NAFLD-transcription factor network. Five hundred twenty-nine nodes and 1,113 edges comprised the PPI network of activated pathway-gene. In addition, 14 common pathways of these two diseases were recognized using Gene Ontology (GO) analysis; among them, regulation of the lipid metabolic process is closely related to both two diseases.

CONCLUSIONS

This study offers hints that NAFLD and DN have a common pathogenesis, and LPL and SPP1 are the most relevant crosstalk genes. Based on the common pathways and optimal crosstalk genes, our proposal carried out further research to disclose the etiology and pathology between the two diseases.

The association between NAFLD and risk of chronic kidney disease: a cross-sectional study

Objective:

The aim of this study was to evaluate the association between nonalcoholic fatty liver disease (NAFLD) and NAFLD with different comorbidities and risk of chronic kidney disease (CKD) and abnormal albuminuria.

Materials and Methods:

A total of 3872 Chinese individuals excluding those with hepatitis B or C infection and absence of alcohol abuse were included in the study. NAFLD was diagnosed by abdominal ultrasonography. The liver fibrosis was assessed by NAFLD fibrosis score (NFS) and fibrosis-4 index (FIB-4). CKD was defined as an estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m² and/or abnormal albuminuria (urinary albumin-to-creatinine ratio ⩾ 3 mg/mmol). The logistic regression analysis was performed to examine the association between NAFLD and NAFLD with different comorbidities and risk of CKD.

Results:

The prevalence of CKD and abnormal albuminuria was higher in individuals with NAFLD than in those without NAFLD (15.8% vs 11.9%, p < 0.001; 14.8% vs 11.0%, p < 0.001). Logistic regression analysis demonstrated that NAFLD was risk factor of CKD. Notably, after adjustment for sex, age, and DM, NAFLD was associated with 1.31-fold higher risk of prevalent CKD ⩾ 1 (p < 0.05). NAFLD individuals with elder age, DM, obesity, hypertension, MetS, and advanced liver fibrosis had higher risks of both prevalent CKD and abnormal albuminuria than those without comorbidities.

Conclusions:

NAFLD and NAFLD with traditional comorbidities are strongly associated with risk of prevalence of CKD and abnormal albuminuria. Patients with NAFLD especially those with coexisting comorbidities were recommended to carefully access the development of CKD.

Real-world Comorbidity Burden, Health Care Utilization, and Costs of Nonalcoholic Steatohepatitis Patients With Advanced Liver Diseases

GOALS

This study evaluates the real-world comorbidity burden, health care resource utilization (HRU), and costs among nonalcoholic fatty liver disease/nonalcoholic steatohepatitis (NAFLD/NASH) patients with advanced liver diseases [compensated cirrhosis (CC), decompensated cirrhosis (DCC), liver transplantation (LT), hepatocellular carcinoma (HCC)].

BACKGROUND

NAFLD/NASH is a leading cause of liver diseases.

MATERIALS AND METHODS

Adult NAFLD/NASH patients were identified retrospectively from MarketScan Commercial claims (2006-2016). Following initial NAFLD/NASH diagnosis, advanced liver diseases were identified using the first diagnosis as their index date. Mean annual all-cause HRU and costs (2016 USD) were reported. Adjusted costs were estimated through generalized linear models. Cumulative costs were illustrated for patient subsets with variable follow-up for each stage.

RESULTS

Within the database, 485,774 NAFLD/NASH patients met eligibility criteria. Of these, 93.4% (453,564) were NAFLD/NASH patients without advanced liver diseases, 1.6% (7665) with CC, 3.3% (15,833) with DCC, 0.1% (696) with LT, and 0.1% (428) with HCC. Comorbidity burden was high and increased as patients progressed through liver disease severity stages. Compared with NAFLD/NASH without advanced liver diseases (adjusted costs: $23,860), the annual cost of CC, DCC, LT, and HCC were 1.22, 5.64, 8.27, and 4.09 times higher [adjusted costs: $29,078, $134,448, $197,392, and $97,563 (P<0.0001)]. Inpatient admissions significantly drove increasing HRU.

CONCLUSION

Study findings suggest the need for early identification and effective management of NAFLD/NASH patients to minimize comorbidity burden, HRU, and costs in the privately insured US population.

The Protective Effects of Live and Pasteurized Akkermansia muciniphila and Its Extracellular Vesicles against HFD/CCl4-Induced Liver Injury

Akkermansia muciniphila, as a member of the gut microbiota, has been proposed as a next-generation probiotic. Liver fibrosis is the main determinant of liver dysfunction and mortality in patients with chronic liver disease. In this study, we aimed to determine the beneficial effects of live and pasteurized A. muciniphila and its extracellular vesicles (EVs) on the prevention of liver fibrosis. The response of hepatic stellate cells (HSCs) to live and pasteurized A. muciniphila and its EVs was examined in quiescent, lipopolysaccharide (LPS)-activated LX-2 cells. Liver fibrosis was induced in 8-week-old C57BL/6 mice, using a high-fat diet (HFD) and carbon tetrachloride (CCl4) administration for 4 weeks. The mice were concomitantly treated via oral gavage with three forms of bacteria. The relative expression of different fibrosis and inflammatory markers was assessed in the tissues. Histological markers, serum biochemical parameters, and cytokine production were also analyzed, and their correlations with the relative abundance of targeted fecal bacteria were examined. All A. muciniphila preparations exhibited protective effects against HSC activation; however, EVs showed the greatest activity in HSC regression. Oral gavage with A. muciniphila ameliorated the serum biochemical and inflammatory cytokines and improved liver and colon histopathological damages. The relative expression of fibrosis and inflammatory biomarkers was substantially attenuated in the tissues of all treated mice. The composition of targeted stool bacteria in the live A. muciniphila group was clearly different from that in the fibrosis group. This study indicated that A. muciniphila and its derivatives could successfully protect against HFD/CCl4-induced liver injury. However, further studies are needed to prove the beneficial effects of A. muciniphila on the liver. IMPORTANCE Akkermansia muciniphila, as a member of the gut microbiota, has been proposed as a next-generation probiotic. Liver fibrosis is the main determinant of liver dysfunction and mortality in patients with chronic liver disease. In this study, we aimed to determine the beneficial effects of live and pasteurized A. muciniphila and its extracellular vesicles (EVs) on the prevention of liver fibrosis. The results of the present study indicated that oral administration of live and pasteurized A. muciniphila and its EVs could normalize the fecal targeted bacteria composition, improve the intestinal permeability, modulate inflammatory responses, and subsequently prevent liver injury in HFD/CCl4-administered mice. Following the improvement of intestinal and liver histopathology, HFD/CCl4-induced kidney damage and adipose tissue inflammation were also ameliorated by different A. muciniphila treatments.

Tim-1 Deficiency Aggravates High-Fat Diet-Induced Steatohepatitis in Mice

Non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH) is commonly associated with obesity and characterized by excessive lipid accumulation and liver inflammation. The T cell immunoglobulin and mucin domain 1 (Tim-1), also known as hepatitis A virus cellular receptor 1 (Havcr-1) and kidney injury molecule 1 (Kim-1), has been shown to affect innate immunity-driven proinflammatory cascade in liver ischemia-reperfusion injury. However, its contribution to obesity-related NAFLD/NASH remains unknown. Thus, this study was designed to evaluate the role of Tim-1 in obesity-related liver inflammation and injury in wild-type (WT) and Tim-1-deficient (Tim-1^-/-) C57BL/6J mice fed a high-fat diet (HFD) for 5-6 months. HFD feeding induced steatosis and upregulated Tim-1 gene expression in the liver of WT mice. Surprisingly, Tim-1^-/- mice on HFD diet exhibited an exacerbation of hepatic steatosis, accompanied with an elevation of protein levels of fatty acid translocase CD36 and sterol regulatory element binding protein 1 (SREBP1). Tim-1 deficiency also enhanced HFD-induced liver inflammation and injury, as evidenced by augmented increase in hepatic expression of pro-inflammatory factor lipocalin 2 and elevated serum alanine transaminase (ALT). In addition, gene expression of type I, III and IV collagens and liver fibrosis were greatly enhanced in HFD Tim-1^-/- mice compared with HFD WT mice. HFD-induced hepatic expression of YM-1, a specific mouse M2 macrophage marker, was further upregulated by deletion of Tim-1. Together, these results show that Tim-1 deficiency aggravates the effects of HFD diet on lipid accumulation and liver fibrosis, most likely through enhanced infiltration and activation of inflammatory cells.

Lipid Disorders in NAFLD and Chronic Kidney Disease

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver dysfunction and is characterized by exaggerated lipid accumulation, inflammation and even fibrosis. It has been shown that NAFLD increases the risk of other chronic diseases, particularly chronic kidney disease (CKD). Lipid in excess could lead to liver and kidney lesions and even end-stage disease through diverse pathways. Dysregulation of lipid uptake, oxidation or de novo lipogenesis contributes to the toxic effects of ectopic lipids which promotes the development and progression of NAFLD and CKD via triggering oxidative stress, apoptosis, pro-inflammatory and profibrotic responses. Importantly, dyslipidemia and release of pro-inflammatory cytokines caused by NAFLD (specifically, nonalcoholic steatohepatitis) are considered to play important roles in the pathological progression of CKD. Growing evidence of similarities between the pathogenic mechanisms of NAFLD and those of CKD has attracted attention and urged researchers to discover their common therapeutic targets. Here, we summarize the current understanding of molecular aberrations underlying the lipid metabolism of NAFLD and CKD and clinical evidence that suggests the relevance of these pathways in humans. This review also highlights the orchestrated inter-organ cross-talk in lipid disorders, as well as therapeutic options and opportunities to counteract NAFLD and CKD.

Early Chronic Kidney Disease (G1-G3a) in Combination with Steatosis as a Predictor of Incident Ischemic Heart Disease: A Longitudinal Study in Non-Diabetic Koreans

Hepatic steatosis and chronic kidney disease (CKD) in the advanced stages are closely related to cardiovascular diseases. Despite the potential connection between early CKD (G1-G3a) and hepatic steatosis on cardiometabolic risks, few studies have revealed their causal link to ischemic heart disease (IHD). We prospectively investigated the combined effect of CKD in earlier stages and hepatic steatosis on incident IHD risk in large-scale, non-diabetic Koreans. Data were assessed from 16,531 participants without diabetes from the Health Risk Assessment Study (HERAS) and Korea Health Insurance Review and Assessment (HIRA) data. We divided the study population into four groups according to the existence of early CKD and hepatic steatosis: controls, early CKD only, hepatic steatosis only, and both early CKD and hepatic steatosis. We prospectively assessed hazard ratios (HRs) with 95% confidence intervals (CIs) for IHD using multivariate Cox proportional-hazard regression models over a 50-month period. During the follow-up period, 326 (2.0%) patients developed IHD. HRs of IHD in the four groups were 1.00 (controls), 1.26 (95% CI 0.72–2.19), 1.19 (95% CI 0.90–1.57) and 1.76 (95% CI 1.04–2.97), respectively, after adjusting for potential confounding variables. Even less than stage 3A, CKD could precede and predict IHD in patients with hepatic steatosis.

Qing-Re-Xiao-Zheng Formula Modulates Gut Microbiota and Inhibits Inflammation in Mice With Diabetic Kidney Disease

Evidence indicates that the metabolic inflammation induced by gut microbiota dysbiosis contributes to diabetic kidney disease. Prebiotic supplementations to prevent gut microbiota dysbiosis, inhibit inflammatory responses, and protect the renal function in DKD. Qing-Re-Xiao-Zheng formula (QRXZF) is a Traditional Chinese Medicine (TCM) formula that has been used for DKD treatment in China. Recently, there are growing studies show that regulation of gut microbiota is a potential therapeutic strategy for DKD as it is able to reduce metabolic inflammation associated with DKD. However, it is unknown whether QRXZF is effective for DKD by regulating of gut microbiota. In this study, we investigated the reno-protective effect of QRXZF by exploring its potential mechanism between gut microbiota and downstream inflammatory pathways mediated by gut-derived lipopolysaccharide (LPS) in the kidney. High-fat diet (HFD) and streptozotocin injection-induced DKD mice model was established to assess the QRXZF effect in vivo. Mice treated with QRXZF for 8 weeks had significantly lower levels of urinary albumin, serum cholesterol and triglycerides. The renal injuries observed through histological analysis were attenuated as well. Also, mice in the QRXZF group had higher levels of Zonula occludens protein-1 (ZO-1) expression, lower levels of serum fluorescein-isothiocyanate (FITC)-dextran and less-damaged colonic mucosa as compared to the DKD group, implying the benefit role for the gut barrier integrity. QRXZF treatment also reversed gut dysbiosis and reduced levels of gut-derived LPS. Notably, the expression of toll-like receptor 4 (TLR4) and nuclear factor-κB (NF-κB), which are important inflammation pathways in DKD, were suppressed in the QRXZF groups. In conclusion, our results indicated that the reno-protective effects of QRXZF was probably associated with modulating gut microbiota and inhibiting inflammatory responses in the kidney.

Hepatoprotective effects of flavonoids from common buckwheat hulls in type 2 diabetic rats and HepG2 cells

Flavonoids from common buckwheat hulls (BHFs) show significant antioxidant and antidiabetic potential. However, their hepatoprotective property is yet to be defined. This study aims to examine the hepatoprotective effect of BHFs in type 2 diabetes mellitus (T2DM) rats and chronic high glucose-damaged HepG2 cells. Results showed that BHF treatment significantly relieves the state of insulin resistance, thereby reducing blood glucose and improving oxidative stress in T2DM rats. It is worth mentioning that BHF treatment improved diabetes-induced liver damage disorders, manifested as the clearance of liver fat and the decline of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities. In vitro, HepG2 cells pretreated with BHFs maintained higher superoxide dismutase (SOD), glutathione peroxidase (GSH-px), and catalase (CAT) activities than the unprotected group. In parallel, compared with the unprotected group, BHFs significantly reduced the leakage of ALT and AST in pre-protected group dose-dependently. These results indicated that BHFs had considerable antioxidant and hepatoprotective potential and could be promising to be used as nutraceuticals and dietary supplements to prevent and/or protect against liver disorders.

NAFLD and renal function in children: is there a genetic link?

Introduction: Over the past decades, a large amount of both adult and pediatric data has shown relationship between Nonalcoholic Fatty Liver Disease (NAFLD) and chronic kidney disease (CKD), resulting in an overall increased cardiometabolic burden. In view of the remarkable role of the genetic background in the NAFLD pathophysiology, a potential influence of the major NAFLD polymorphisms (e.g. the I148M variant of the Patatin-like phospholipase containing domain 3 (PNPLA3) gene, the E167K allele of the Transmembrane 6 superfamily member 2 (TM6SF2), the hydroxysteroid 17-beta dehydrogenase 13 (HSD17B13), and the Membrane bound O-acyltransferase domain containing 7-transmembrane channel-like 4 (MBOAT7-TMC4) genes) on renal function has been supposed. A shared metabolic and proinflammatory pathogenesis has been hypothesized, but the exact mechanism is still unknown.Areas covered: We provide a comprehensive review of the potential genetic link between NAFLD and CKD in children. Convincing both adult and pediatric evidence supports this association, but there is some dispute especially in childhood.Expert opinion: Evidence supporting a potential genetic link between NAFLD and CKD represents an intriguing aspect with a major clinical implication because of its putative role in improving strategy programs to counteract the higher cardiometabolic risk of these patients.

Autofluorescence spectroscopy and multivariate analysis for predicting the induced damages to other organs due to liver fibrosis

When our liver does not work well, it can induce damage to other organs causing their dysfunction. With this background, we aim to study the effect of liver fibrosis on other organs such as heart, lungs, kidney and spleen by assessing the variations in the inherent emission property of the tissue, using fluorescence spectroscopy. Fluorescence emission spectra from excised organs of liver fibrosis induced rats were collected at excitation wavelengths 320 and 410 nm. Optical redox ratio derived from the spectral data supported by multivariate statistical analysis, principal component analysis followed by linear discriminant analysis (PCA-LDA) distinguished between control and fibrosis induced groups. The two different excitation wavelength provided variations in the endogenous flurophores collagen, nicotinamide adenine dinucleotide (NADH), flavin adenine dinucleotide (FAD), lipopigments and porphyrins. Additionally, evaluation of redox ratio provided variations in tissue metabolic activity of different organs. The PCA-LDA modelling yielded a sensitivity of 85 to 97% and specificity of 80 to 96% on 320 nm excitation and a sensitivity of 72 to 100% and specificity of 59 to 100% on 410 nm excitation. Fluorescence emission spectral study along with multivariate analysis paved way to identify the biochemical alterations caused to other organs due to the development of liver fibrosis, which could lead to their damage and dysfunction.

Bile acids induced hepatic lipid accumulation in mice by inhibiting mRNA expression of patatin-like phospholipase domain containing 3 and microsomal triglyceride transfer protein

Preliminary studies have shown that a lithogenic diet (LG), which contains cholesterol and cholic acid, induces gallstones and hepatic lipid accumulation (HLA), and reduction of blood triglyceride in mice. We hypothesized that an LG induces HLA by diminishing hepatic triglyceride excretion; however, there is no clear understanding of the mechanism of LG-induced HLA. This study aimed to investigate transcript expression related to the synthesis, expenditure, and efflux of hepatic triglyceride, in mice fed an LG for 4 weeks. Results showed lower plasma concentrations of triglyceride in the LG group than in the control group, but no symptoms of hepatic injury were observed. Hepatic mRNA expressions of patatin-like phospholipase domain containing 3 (Pnpla3), microsomal triglyceride transfer protein (Mttp), and acyl-CoA oxidase 1 (Acox1) were also reduced in the LG group. Deoxycholic acid and lithocholic acid promoted intracellular lipid accumulation, reduced triglyceride concentration in media, and suppressed expression of PNPLA3 and MTTP in HepG2 human hepatoma cells. These findings suggest that deoxycholic acid and lithocholic acid promote HLA by inhibiting the expression of PNPLA3, ACOX1, and MTTP that are involved in lipid metabolism.

Uninephrectomy and class II PI3K-C2β inactivation synergistically protect against obesity, insulin resistance and liver steatosis in mice

Uninephrectomy (UNx) in living kidney donors for transplantation is now routine clinical practice. While chronic kidney disease, due to bilateral kidney dysfunction, is associated with insulin resistance, liver steatosis, and type 2 diabetes, the metabolic impact of UNx remains unclear. To better understand the crosstalk between the kidney and insulin target tissues, we studied the metabolic consequences of UNx and the potential involvement of class II PI3K-C2β, the inactivation of which has been reported to result in insulin sensitization. Mice underwent UNx or sham operation followed by either normal chow or high-fat diet (HFD). Seventeen weeks post-UNx, mice showed improved glucose tolerance, insulin sensitivity, and decreased HFD-induced liver steatosis. This was associated with an enhanced serum FGF21 and insulin-stimulated Akt signaling in the liver and muscle of both lean and obese mice. Remarkably, the combination of UNx and PI3K-C2β inactivation protected against HFD-induced obesity and further potentiated the metabolic improvement observed in WT UNx mice correlating with a synergistic increase in metabolic tissues of (1) insulin-stimulated Akt signaling (2) FGFR1 and βKlotho expression. We demonstrated a potential beneficial effect of kidney donation and more effectively with PI3K-C2β inactivation to protect against metabolic disorders through a mutual insulin/FGF21 sensitization.

Current and Evolving Indications for Simultaneous Liver Kidney Transplantation

This review will discuss the etiologies of kidney disease in liver transplant candidates, provide a historical background of the prior evolution of simultaneous liver-kidney (SLK) transplant indications, discuss the current indications for SLK including Organ Procurement and Transplantation Network policies and Model for End Stage Liver Disease exception points, as well as provide an overview of the safety net kidney transplant policy. Finally, the authors explore unanswered questions and future research needed in SLK transplantation.

CDKN2A deregulation in fatty liver disease and its accelerative role in the process of lipogenesis

Previous literature has indicated that cyclin-dependent kinase inhibitor 2 A (CDKN2A) is upregulated, while the Protein Inhibitor of Activated STAT1 (PIAS1) is downregulated in the liver tissues of obese mice. The current study aimed to investigate the relationship between CDKN2A and PIAS1 in the lipogenesis of fatty liver disease. In the C57BL/6J db/db mouse model and hepatocyte model of fatty liver, the expression pattern of CDKN2A, PIAS1, Protein arginine methyltransferase 1 (PRMT1) and CASP8 and FADD-like apoptosis regulator (CFLAR) was characterized by RNA quantitative and Western blot analysis. The lipogenesis-related genes (Srebp1c and Fas) in the liver tissues and cells were employed in the assessment of lipogenesis in response to gain- or loss-of-function of CDKN2A, PIAS1, PRMT1, and CFLAR, while triglyceride and fat content were evaluated in relation to fat accumulation. Western blot analysis was conducted to determine c-Jun amino-terminal kinase (JNK) phosphorylation, while the ubiquitination of CFLAR and SUMOylation of PIAS1 was examined by immunoprecipitation. PIAS1 and CFLAR were downregulated, while CDKN2A, PRMT1, and phosphorylation of JNK was elevated in the tissues and cells of the fatty liver models. Our results suggested that CDKN2A enhanced the SUMOylation of PIAS1 to reduce the expression of PIAS1. PRMT1 downregulated CFLAR by triggering its ubiquitination, while CFLAR repressed phosphorylation of JNK. The in vitro and in vivo results indicated that CDKN2A silencing prevented lipogenesis and fat accumulation by impairing the PRMT1-dependent ubiquitination of CFLAR and blocking the phosphorylation of JNK. Taken together, the central observations of our study demonstrate that targeting CDKN2A contributes to the suppression of lipogenesis and fat accumulation in fatty liver disease. The findings of our study highlight the potential of CDKN2A as a promising target against fatty liver.