Metabolic dysfunction associated fatty liver disease and coronavirus disease 2019: clinical relationship and current management

Molecular mechanisms of metabolic disease-associated hepatic inflammation in non-alcoholic fatty liver disease and non-alcoholic steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is the leading chronic liver disease worldwide, with a progressive form of non-alcoholic steatohepatitis (NASH). It may progress to advanced liver diseases, including liver fibrosis, cirrhosis, and hepatocellular carcinoma. NAFLD/NASH is a comorbidity of many metabolic disorders such as obesity, insulin resistance, type 2 diabetes, cardiovascular disease, and chronic kidney disease. These metabolic diseases are often accompanied by systemic or extrahepatic inflammation, which plays an important role in the pathogenesis and treatment of NAFLD or NASH. Metabolites, such as short-chain fatty acids, impact the function, inflammation, and death of hepatocytes, the primary parenchymal cells in the liver tissue. Cholangiocytes, the epithelial cells that line the bile ducts, can differentiate into proliferative hepatocytes in chronic liver injury. In addition, hepatic non-parenchymal cells, including liver sinusoidal endothelial cells, hepatic stellate cells, and innate and adaptive immune cells, are involved in liver inflammation. Proteins such as fibroblast growth factors, acetyl-coenzyme A carboxylases, and nuclear factor erythroid 2-related factor 2 are involved in liver metabolism and inflammation, which are potential targets for NASH treatment. This review focuses on the effects of metabolic disease-induced extrahepatic inflammation, liver inflammation, and the cellular and molecular mechanisms of liver metabolism on the development and progression of NAFLD and NASH, as well as the associated treatments.

High-cholesterol diet in combination with hydroxypropyl-beta-cyclodextrin induces NASH-like disorders in the liver of rats

Non-alcoholic fatty liver disease (NAFLD) is a general term for fatty liver disease not caused by viruses or alcohol. Fibrotic hepatitis, cirrhosis, and hepatocellular carcinoma can develop. The recent increase in NAFLD incidence worldwide has stimulated drug development efforts. However, there is still no approved treatment. This may be due in part to the fact that non-alcoholic steatohepatitis (NASH) pathogenesis is very complex, and its mechanisms are not well understood. Studies with animals are very important for understanding the pathogenesis. Due to the close association between the establishment of human NASH pathology and metabolic syndrome, several animal models have been reported, especially in the context of overnutrition. In this study, we investigated the induction of NASH-like pathology by enhancing cholesterol absorption through treatment with hydroxypropyl-beta-cyclodextrin (CDX). Female Sprague-Dawley rats were fed a normal diet with normal water (control group); a high-fat (60 kcal%), cholesterol (1.25 %), and cholic acid (0.5 %) diet with normal water (HFCC group); or HFCC diet with 2 % CDX water (HFCC+CDX group) for 16 weeks. Compared to the control group, the HFCC and HFCC+CDX groups showed increased blood levels of total cholesterol, aspartate aminotransferase, and alanine aminotransferase. At autopsy, parameters related to hepatic lipid synthesis, oxidative stress, inflammation, and fibrosis were elevated, suggesting the development of NAFLD/NASH. Elevated levels of endoplasmic reticulum stress-related genes were evident in the HFCC+CDX group. In the novel rat model, excessive cholesterol intake and accelerated absorption contributed to NAFLD/NASH pathogenesis.

Targeting patients for early COVID-19 therapy; Pre-infection metabolic dysfunction, polycystic ovary syndrome and risk of severe disease in patients under 65: A Massachusetts community-based observational study

INTRODUCTION

The demographics of those developing severe coronavirus disease (COVID-19) outcomes are shifting to younger patients. In an observational study utilizing electronic health records from a Massachusetts group medical practice, we identified 5025 patients with confirmed COVID-19 from March 1 to December 18, 2020. Of these, 3870 were under 65 years of age. We investigated the hypothesis that pre-infection metabolic or immunologic dysregulation including polycystic ovary syndrome (PCOS) increased risk of serious COVID-19 outcomes in patients under 65 years of age.

MATERIALS AND METHODS

We compared those with COVID-19 related hospitalization or mortality to all other COVID-19 patients, using a case control approach. Using logistic regression and propensity score modeling, we evaluated risk of developing severe COVID-19 outcomes (hospitalization or death) in those with pre-infection comorbidities, metabolic risk factors, or PCOS.

RESULTS

Overall, propensity score matched analyses demonstrated pre-infection elevated liver enzymes alanine aminotransferase (ALT) >40, aspartate aminotransferase (AST) >40 and blood glucose ≥215 mg/dL were associated with more severe COVID-19 outcomes, OR = 1.74 (95% CI 1.31, 2.31); OR = 1.98 (95% CI 1.52, 2.57), and OR = 1.55 (95% CI 1.08, 2.23) respectively. Elevated hemoglobin A1C or blood glucose levels were even stronger risk factors for severe COVID-19 outcomes among those aged < 65, OR = 2.31 (95% CI 1.14, 4.66) and OR = 2.42 (95% CI 1.29, 4.56), respectively. In logistic regression models, women aged < 65 with PCOS demonstrated more than a four-fold increased risk of severe COVID-19, OR 4.64 (95% CI 1.98, 10.88).

CONCLUSION

Increased risk of severe COVID-19 outcomes in those < age 65 with pre-infection indicators of metabolic dysfunction heightens the importance of monitoring pre-infection indicators in younger patients for prevention and early treatment. The PCOS finding deserves further investigation. Meanwhile women who suffer from PCOS should be carefully evaluated and prioritized for earlier COVID-19 treatment and vaccination.

The Impact of COVID-19 Pandemic Lockdown on the Relationship between Pediatric MAFLD and Renal Function

BACKGROUND

Both direct and indirect effects of COVID-19 have been found in all age groups. In particular, adult data demonstrated significant changes in patients with chronic and metabolic disease (e.g., obesity, diabetes, chronic kidney disease (CKD), and metabolic associated fatty liver dysfunction (MAFLD)), while similar pediatric evidence is still limited. We aimed at investigating the impact of the COVID-19 pandemic lockdown on the relationship between MAFLD and renal function in children with CKD due to congenital abnormalities of the kidney and urinary tract (CAKUT).

METHODS

A total of 21 children with CAKUT and CKD ≥ stage 1 underwent a comprehensive evaluation within 3 months before and 6 months after the first Italian lockdown.

RESULTS

At follow-up, CKD patients with MAFLD presented higher BMI-SDS, serum uric acid, triglycerides, and microalbuminuria levels and lower eGFR levels than those without MAFLD (all p < 0.05). Higher ferritin and white blood cell concentrations were also found in patients with CKD diagnosed with MAFLD than peers without MAFLD (both p = 0.01). Compared to children without MAFLD, a higher delta of BMI-SDS, eGFR levels, and microalbuminuria levels was found in patients with MAFLD.

CONCLUSIONS

Due to the negative influence of the COVID-19 lockdown on cardiometabolic health in childhood, a careful management of children with CKD is warranted.

Implications of metabolic dysfunction associated fatty liver disease in COVID-19

Metabolic associated fatty liver disorder (MAFLD) characterizes the contributing etiologies (i.e., type 2 diabetes mellitus, metabolic syndrome, overweight) of individuals with fatty liver disease that affects 1/3^rd of the world population. In 2020, the coronavirus disease 2019 (COVID-19) crisis was unprecedented, and people with different comorbidities became more susceptible to the infection caused by severe acute respiratory syndrome coronavirus 2. MAFLD patients are frequently obese with added metabolic menace like diabetes, hypertension, and dyslipidemia leading to greater jeopardy of COVID-19. MAFLD patients are 4 to 6-fold more prone towards infections. COVID-19 induces liver injury with elevated levels of aspartate aminotransferase and alanine aminotransferase and insignificantly elevated bilirubin. Hence, MAFLD in COVID-19 patients worsens the condition significantly. The evidence highlighting the interaction between MAFLD and altered liver functioning in COVID-19 suggested that COVID-19 patients with pre-existing MAFLD are at greater risk of morbidity or intensive care unit admission. Direct hepatic injury, enhanced levels of inflammatory cytokines, declined hepatic mitochondrial activity, and compromised immunity are considered as some underlying mechanisms. The main focus of this review is to discuss the implications of metabolic dysfunction associated with fatty liver disease in COVID-19 patients. The review systematically analyzes the effect of striking two worldwide pandemics (MAFLD and COVID-19) together in the present era.

Liver injury in COVID-19 patients with non-alcoholic fatty liver disease: an update

The coronavirus disease 2019 (COVID-19) pandemic has revolutionized the priorities of the medical society worldwide. Although most patients infected with SARS-CoV-2 exhibit respiratory symptoms, other organs may also be involved, including the liver, often resulting in liver injury. Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the world, and its prevalence is expected to increase together with the epidemics of type 2 diabetes and obesity. Data about liver injury during COVID-19 are numerous, while overviews of this infection in patients with NAFLD, both in terms of respiratory and liver, are emerging. In this review, we summarise the current research focusing on COVID-19 in NAFLD patients and discuss the association between liver injury in COVID-19 subjects and non-alcoholic fatty liver disease.

SARS-CoV-2 infection-related deregulation of blood lipids in a patient with -/-LDLR familial homozygous hypercholesterolemia: A case report

BACKGROUND

The effect of SARS-CoV-2 infection in blood lipids of homozygous familial hypercholesterolemia (HoFH) has not been explored.

CASE SUMMARY

We report a case of a 43-year-old male patient with -/-LDLR HoFH with previous history of premature coronary artery disease, coronary artery bypass graft (CABG) and surgical repair of aortic valve stenosis. He presented with an abrupt decrease of his blood lipid levels during acute infection with SARS-CoV2 and subsequently a rebound increase above pre-infection levels, refractory to treatment including LDL-apheresis, statin, ezetimibe and lomitapide up-titration to maximum tolerated doses. Markers of liver stiffness were closely monitored, increased at 9 months and decreased at 18 months after the infection. Potential interactions of hypolipidemic treatment with the viral replication process during the acute phase, as well as therapeutic dilemmas occurring in the post infection period are discussed.

Outcomes of COVID-19 among patients with liver disease

Coronavirus disease 2019 (COVID-19) is primarily a respiratory disease with multi-organ involvement, including impaired liver function. It has been noticed that a significant proportion of COVID-19 patients have liver dysfunction, especially those with a more severe disease course. The coronavirus causes direct damage to the liver using the angiotensin-converting enzyme 2, a cell-surface receptor for cellular entry, that is expressed in the liver. According to previous research, liver enzyme abnormalities were observed in a considerable proportion of COVID-19 patients, and elevated liver transaminases were found in about 20% of these patients, alkaline phosphatase in 6.1%, and gamma-glutamyl transferase in 21.1%. COVID-19 might trigger a deterioration of liver function in patients with pre-existing chronic liver diseases (CLDs) and also in those without previous liver disorders. The majority of COVID-19 patients who develop liver injury are men, the elderly, and those with a higher body mass index. Compared to the general population, COVID-19 is associated with significant morbidity and mortality in patients with liver disease (cirrhosis and liver transplantation recipients). However, some studies indicate that CLDs have a lesser role in determining patient progression towards higher disease severity.

Clinical implications of COVID-19 in patients with metabolic-associated fatty liver disease

People across the world are affected by the "coronavirus disease 2019 (COVID-19)", brought on by the "SARS-CoV type-2 coronavirus". Due to its high incidence in individuals with diabetes, metabolic syndrome, and metabolic-associated fatty liver disease (MAFLD), COVID-19 has gained much attention. The metabolic syndrome's hepatic manifestation, MAFLD, carries a significant risk of type-2-diabetes. The link between the above two conditions has also drawn increasing consideration since MAFLD is intricately linked to the obesity epidemic. Independent of the metabolic syndrome, MAFLD may impact the severity of the viral infections, including COVID-19 or may even be a risk factor. An important question is whether the present COVID-19 pandemic has been fueled by the obesity and MAFLD epidemics. Many liver markers are seen elevated in COVID-19. MAFLD patients with associated comorbid conditions like obesity, cardiovascular disease, renal disease, malignancy, hypertension, and old age are prone to develop severe disease. There is an urgent need for more studies to determine the link between the two conditions and whether it might account for racial differences in the mortality and morbidity rates linked to COVID-19. The role of innate and adaptive immunity alterations in MAFLD patients may influence the severity of COVID-19. This review investigates the implications of COVID-19 on liver injury and disease severity and vice-versa. We also addressed the severity of COVID-19 in patients with prior MAFLD and its potential implications and therapeutic administration in the clinical setting.

A Multidisciplinary Approach and Current Perspective of Nonalcoholic Fatty Liver Disease: A Systematic Review

In recent times, nonalcoholic fatty liver disease (NAFLD) has been considered one of the major causes of liver disease across the world. NAFLD is defined as the deposition of triglycerides in the liver and is associated with obesity and metabolic syndrome. Hyperinsulinemia, insulin resistance (IR), fatty liver, hepatocyte injury, unbalanced proinflammatory cytokines, mitochondrial dysfunction, oxidative stress, liver inflammation, and fibrosis are the main pathogenesis in NAFLD. Recent studies suggest that the action of intestinal microbiota through chronic inflammation, increased intestinal permeability, and energy uptake plays a vital role in NAFLD. Moreover, polycystic ovarian syndrome also causes NAFLD development through IR. Age, gender, race, ethnicity, sleep, diet, sedentary lifestyle, and genetic and epigenetic pathways are some contributing factors of NAFLD that can exacerbate the risk of liver cirrhosis and hepatocellular carcinoma (HCC) and eventually lead to death. NAFLD has various presentations, including fatigue, unexplained weight loss, bloating, upper abdominal pain, decreased appetite, headache, anxiety, poor sleep, increased thirst, palpitation, and a feeling of warmth. Some studies have shown that NAFLD with severe coronavirus disease 2019 (COVID-19) has poor outcomes. The gold standard for NAFLD diagnosis is liver biopsy. Other diagnostic tools are imaging tests, serum biomarkers, microbiota markers, and tests for extrahepatic complications. There are no specific treatments for NAFLD. Therefore, the main concern for NAFLD is treating the comorbid conditions such as anti-diabetic agents for type 2 diabetes mellitus, statins to reduce HCC progression, antioxidants to prevent hepatocellular damage, and bariatric surgery for patients with a BMI of >40 kg/m² and >35 kg/m² with comorbidities. Lifestyle and dietary changes are considered preventive strategies against NAFLD advancement. Inadequate treatment of NAFLD further leads to cardiac consequences, sleep apnea, chronic kidney disease, and inflammatory bowel disease. In this systematic review, we have briefly discussed the risk factors, pathogenesis, clinical features, and numerous consequences of NAFLD. We have also reviewed various guidelines for NAFLD diagnosis along with existing therapeutic strategies for the management and prevention of the disease.

Metabolic dysfunction-associated fatty liver disease in obese youth with insulin resistance and type 2 diabetes

PURPOSE OF REVIEW

The aim of this review is to present the new definition of the disease, defining the epidemiology, risk factors with a particular attention to the role of insulin resistance (IR) and to define the main treatments explored.

RECENT FINDINGS

Nonalcoholic fatty liver disease (NAFLD) was previously considered a primary liver disease, but it would be more correct to consider it a component of the metabolic syndrome (MetS) in which IR might play a key role. Based on these findings, it has been recently proposed to modify the classic term of NAFLD to metabolic dysfunction-associated fatty liver disease (MAFLD) that better reflects the pathophysiology of this complex disease.

SUMMARY

Currently, no treatments approved in childhood are available, thus the only recommended approach is the prevention and correction of the known risk factors, and particularly of IR. However, further studies are needed to better clarify the pathogenetic mechanisms of NAFLD in order to establish more tailored therapies.

COVID-19 Pandemic: Insights into Interactions between SARS-CoV-2 Infection and MAFLD

COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become an ongoing global health pandemic. Since 2019, the pandemic continues to cast a long shadow on all aspects of our lives, bringing huge health and economic burdens to all societies. With our in-depth understanding of COVID-19, from the initial respiratory tract to the later gastrointestinal tract and cardiovascular systems, the multiorgan involvement of this infectious disease has been discovered. Metabolic dysfunction-associated fatty liver disease (MAFLD), formerly named nonalcoholic fatty liver disease (NAFLD), is a major health issue closely related to metabolic dysfunctions, affecting a quarter of the world's adult population. The association of COVID-19 with MAFLD has received increasing attention, as MAFLD is a potential risk factor for SARS-CoV-2 infection and severe COVID-19 symptoms. In this review, we provide an update on the interactions between COVID-19 and MAFLD and its underlying mechanisms.

The impact of dawn to sunset fasting on immune system and its clinical significance in Covid-19 pandemic

Dawn to sunset fasting, a type of intermittent fasting commonly practiced in the month of Ramadan, requires fasting from dawn to sunset without food or liquid intake. Dawn and dusk are two transition time zones of the day that play a critical role in the human circadian rhythm. Practicing dawn to sunset fasting requires the alignment of mealtimes and wake-sleep times with the human biological dawn and dusk. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) impairs immune cell responses at multiple levels and leads to severe Coronavirus Disease 2019 (COVID-19). It generates high levels of pro-inflammatory cytokines and chemokines, also known as a cytokine storm, leads to mitochondrial dysfunction and generation of excessive amounts of mitochondrial reactive oxygen species, downregulates autophagy to escape detection for unchecked replication, and alters gut microbiome composition. Severe cases of COVID-19 have been associated with several comorbidities that impair immune responses (e.g., obesity, diabetes, malignancy) and blood laboratory abnormalities (e.g., elevated procalcitonin, C-reactive protein, interleukin-6 (IL-6), leukocytosis, lymphopenia). Several studies of dawn to sunset fasting showed anti-inflammatory effect by suppressing several pro-inflammatory cytokines, reducing oxidative stress, inducing a proteome response associated with increased autophagy, remodeling the gut microbiome, and improving the components of metabolic syndrome (e.g., obesity, blood glucose levels, blood pressure, lipids). In conclusion, dawn to sunset fasting has the potential to optimize the immune system function against SARS-CoV-2 during the COVID-19 pandemic as it suppresses chronic inflammation and oxidative stress, improves metabolic profile, and remodels the gut microbiome. This review presents scientific literature related to the effects of dawn to sunset fasting on the immune system. Studies are needed to assess and confirm the potential benefits of dawn to sunset fasting against SARS-CoV-2.

Effect of Nutrition Education in NAFLD Patients Undergoing Simultaneous Hyperlipidemia Pharmacotherapy: A Randomized Controlled Trial

BACKGROUND

Patients with non-alcoholic fatty liver disease (NAFLD) have a high prevalence of combined hyperlipidemia. The importance of nutritional education is well-known in NAFLD, but the impact of medical nutrition therapy (MNT) is unclear in patients with NAFLD with hyperlipidemia. The purpose of this study is to investigate the effect of MNT on the improvement of steatohepatitis in patients with NAFLD taking antihyperlipidemic medications.

METHODS

Nondiabetic patients with dyslipidemia were prospectively randomized (1:1) either to the MNT group or the control group with standard advice for 48 weeks with simultaneous statin/ezetimibe combination pharmacotherapy at three tertiary centers in Korea.

RESULTS

Sixty-six patients were enrolled. Among them, 18 patients dropped out and, overall, 48 patients (MNT group 27, control group 21) were prospectively analyzed in the study. The serum ALT level at 48 weeks between the two groups was not significantly different (66.6 ± 37.7 IU/L vs. 57.4 ± 36.7 IU/L, p = 0.40). Serum liver enzymes, controlled attenuation parameter and fibrosis-4 index were significantly improved within the MNT group after 48 weeks compared to baseline. There was no significant difference between the two groups other than the NAFLD fibrosis score (p = 0.017).

CONCLUSIONS

Although there were no significant differences between the two groups in terms of steatosis, metabolic and fibrosis surrogate indicators after 48 weeks, MNT groups showed significant improvement within patient analysis over time. Future studies with a larger number of subjects and a longer study period regarding the effect of MNT are warranted.