Theoretical basis of a beneficial role for vitamin D in viral hepatitis

Study on gene expression in the liver at various developmental stages of human embryos

Background

The normal development of the liver during human embryonic stages is critical for the functionality of the adult liver. Despite this, the essential genes, biological processes, and signal pathways that drive liver development in human embryos remain poorly understood.

Methods

In this study, liver samples were collected from human embryos at progressive developmental stages, ranging from 2-month-old to 7-month-old. Highly expressed genes and their associated enrichment processes at various developmental stages of the liver were identified through transcriptomic sequencing.

Results

The findings indicated that genes associated with humoral immune responses and B-cell-mediated immunity were highly expressed during the early developmental stages. Concurrently, numerous genes related to vitamin response, brown adipocyte differentiation, T cell differentiation, hormone secretion, hemostasis, peptide hormone response, steroid metabolism, and hematopoietic regulation exhibited increased expression aligned with liver development. Our results suggest that the liver may possess multiple functions during embryonic stages, beyond serving hematopoietic roles. Moreover, this study elucidated the complex regulatory interactions among genes involved in lymphocyte differentiation, the regulation of hemopoiesis, and liver development. Consequently, the development of human embryonic liver necessitates the synergistic regulation of numerous genes. Notably, alongside conventionally recognized genes, numerous previously uncharacterized genes involved in liver development and function were also identified.

Conclusion

These findings establish a critical foundation for future research on liver development and diseases arising from fetal liver abnormalities.

Vitamin D serum level in participants with positive history of recurrent herpes labialis

AIM

Vitamin D plays an important role in immune system regulation, also its deficiency is assumed to affect the patients' predisposition to viral diseases such as recurrent herpes labialis. In this cross-sectional study, we tried to compare the mean serum level of vitamin D in participants with a positive history of recurrent herpes labial lesions and healthy controls.

MATERIALS AND METHODS

The vitamin D serum level of 43 participants with a positive history of recurrent herpes labial lesions who were referred to the Motahhari laboratory in Shiraz during 2020-2022, was compared with 42 healthy controls. It was assessed by an Elisa kit. An Independent T-test was used to compare the vitamin D serum level between two genders. In order to assess the mean age value and gender distribution, an independent T-test and Pearson Chi-Square were used, respectively for the two groups. The serum vitamin D level was compared between both control and test groups.

RESULTS

There was no significant difference between vitamin D mean serum levels in the two evaluated groups (p.value = 0.72). Although the age (p.value = 0.09) and recurrence (p.value = 0.13) of herpes labialis had no statistically significant relation to the vitamin D serum level, the healing duration of herpes labialis was inversely related (p.value = 0.01). Lower-level of serum vitamin D were accompanied by a longer healing duration of the lesions.

CONCLUSION

Although the vitamin D serum level of participants with a history of recurrent herpes labialis had no relation with age and herpes virus recurrence frequency, a longer healing duration of lesions had been reported in patients with lower serum levels of vitamin D.

Role of Vitamin D in Liver Disease and Complications of Advanced Chronic Liver Disease

Vitamin D is a crucial nutrient with many pleiotropic effects on health and various chronic diseases. The purpose of this review is to provide a detailed report on the pathophysiological mechanisms underlying vitamin D deficiency in patients with chronic liver disease, addressing the different liver etiologies and the condition of advanced chronic liver disease (cirrhosis) with related complications. To date, patients with liver disease, regardless of underlying etiology, have been shown to have reduced levels of vitamin D. There is also evidence of the predictive role of vitamin D values in complications and progression of advanced disease. However, specific indications of vitamin D supplementation are not conclusive concerning what is already recommended in the general population. Future studies should make an effort to unify and validate the role of vitamin D supplementation in chronic liver disease.

Vitamin D supplementation for chronic liver diseases in adults

BACKGROUND

Vitamin D deficiency is often reported in people with chronic liver diseases. Improving vitamin D status could therefore be beneficial for people with chronic liver diseases.

OBJECTIVES

To assess the beneficial and harmful effects of vitamin D supplementation in adults with chronic liver diseases.

SEARCH METHODS

We searched the Cochrane Hepato-Biliary Group Controlled Trials Register, CENTRAL, MEDLINE Ovid, Embase Ovid, LILACS, Science Citation Index Expanded, and Conference Proceedings Citation Index-Science. We also searched ClinicalTrials.gov  and the World Health Organization International Clinical Trials Registry Platform. We scanned bibliographies of relevant publications and enquired experts and pharmaceutical companies as to additional trials. All searches were up to November 2020.

SELECTION CRITERIA

Randomised clinical trials that compared vitamin D at any dose, duration, and route of administration versus placebo or no intervention in adults with chronic liver diseases. Vitamin D could have been administered as supplemental vitamin D (vitamin D₃ (cholecalciferol) or vitamin D₂ (ergocalciferol)), or an active form of vitamin D (1α-hydroxyvitamin D (alfacalcidol), 25-hydroxyvitamin D (calcidiol), or 1,25-dihydroxyvitamin D (calcitriol)).

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. We used GRADE to assess the certainty of evidence.

MAIN RESULTS

We included 27 randomised clinical trials with 1979 adult participants. This review update added 12 trials with 945 participants. We assessed all trials as at high risk of bias. All trials had a parallel-group design. Eleven trials were conducted in high-income countries and 16 trials in middle-income countries. Ten trials included participants with chronic hepatitis C, five trials participants with liver cirrhosis, 11 trials participants with non-alcoholic fatty liver disease, and one trial liver transplant recipients. All of the included trials reported the baseline vitamin D status of participants. Participants in nine trials had baseline serum 25-hydroxyvitamin D levels at or above vitamin D adequacy (20 ng/mL), whilst participants in the remaining 18 trials were vitamin D insufficient (less than 20 ng/mL). Twenty-four trials administered vitamin D orally, two trials intramuscularly, and one trial intramuscularly and orally. In all 27 trials, the mean duration of vitamin D supplementation was 6 months, and the mean follow-up of participants from randomisation was 7 months. Twenty trials (1592 participants; 44% women; mean age 48 years) tested vitamin D₃ (cholecalciferol); three trials (156 participants; 28% women; mean age 54 years) tested vitamin D₂; four trials (291 participants; 60% women; mean age 52 years) tested 1,25-dihydroxyvitamin D; and one trial (18 participants; 0% women; mean age 52 years) tested 25-hydroxyvitamin D. One trial did not report the form of vitamin D. Twelve trials used a placebo, whilst the other 15 trials used no intervention in the control group. Fourteen trials appeared to be free of vested interest. Eleven trials did not provide any information on clinical trial support or sponsorship. Two trials were funded by industry. We are very uncertain regarding the effect of vitamin D versus placebo or no intervention on all-cause mortality (risk ratio (RR) 0.86, 95% confidence interval (CI) 0.51 to 1.45; 27 trials; 1979 participants). The mean follow-up was 7 months (range 1 to 18 months). We are very uncertain regarding the effect of vitamin D versus placebo or no intervention on liver-related mortality (RR 1.62, 95% CI 0.08 to 34.66; 1 trial; 18 participants) (follow-up: 12 months); serious adverse events such as hypercalcaemia (RR 5.00, 95% CI 0.25 to 100.8; 1 trial; 76 participants); myocardial infarction (RR 0.75, 95% CI 0.08 to 6.81; 2 trials; 86 participants); thyroiditis (RR 0.33, 95% CI 0.01 to 7.91; 1 trial; 68 participants); circular haemorrhoidal prolapse (RR 3.00, 95% CI 0.14 to 65.9; 1 trial; 20 participants); bronchopneumonia (RR 0.33, 95% CI 0.02 to 7.32; 1 trial 20 participants); and non-serious adverse events. The certainty of evidence for all outcomes is very low. We found no data on liver-related morbidity such as gastrointestinal bleeding, hepatic encephalopathy, hepatorenal syndrome, ascites, or liver cancer. There were also no data on health-related quality of life. The evidence is also very uncertain regarding the effect of vitamin D versus placebo or no intervention on rapid, early, and sustained virological response in people with chronic hepatitis C.

AUTHORS' CONCLUSIONS

Given the high risk of bias and insufficient power of the included trials and the very low certainty of the available evidence, vitamin D supplementation versus placebo or no intervention may increase or reduce all-cause mortality, liver-related mortality, serious adverse events, or non-serious adverse events in adults with chronic liver diseases. There is a lack of data on liver-related morbidity and health-related quality of life. Further evidence on clinically important outcomes analysed in this review is needed.

New insights into the role of vitamin D in hepatocellular carcinoma

In addition to being crucial for host immune defense, vitamin D is involved in cell proliferation, apoptosis, differentiation, inflammation, invasion and metastasis, angiogenesis and micro-RNA modulation. To date, clinical studies have demonstrated that vitamin D deficiency is common not only in patients with chronic liver diseases but also in those with hepatocellular carcinoma (HCC). Experimental studies have also demonstrated that vitamin D and its receptors are related to the occurrence of HCC and the prognoses of patients with HCC. Areas covered: In this review, we discuss the potential anti-tumor role of vitamin D in HCC based on current findings from epidemiological studies, basic science, and clinical studies and provide new insights into the pathogenesis and treatment of HCC. Expert commentary: Recent studies have revealed the anti-tumor effects of vitamin D to a certain degree. Vitamin D and its analogs may provide new treatment targets and prognostic factors for HCC that might be essential for the primary or secondary prevention of HCC and the monitoring of its progression.

Calcitriol Inhibits HCV Infection via Blockade of Activation of PPAR and Interference with Endoplasmic Reticulum-Associated Degradation

Vitamin D has been identified as an innate anti-hepatitis C virus (HCV) agent but the possible mechanisms for this issue remain unclear. Here, we clarified the mechanisms of calcitriol-mediated inhibition of HCV infection. Calcitriol partially inhibited HCV infection, nitric oxide (NO) release and lipid accumulation in Huh7.5 human hepatoma cells via the activation of vitamin D receptor (VDR). When cells were pretreated with the activators of peroxisome proliferator-activated receptor (PPAR)-α (Wy14643) and -γ (Ly171883), the calcitriol-mediated HCV suppression was reversed. Otherwise, three individual stimulators of PPAR-α/β/γ blocked the activation of VDR. PPAR-β (linoleic acid) reversed the inhibition of NO release, whereas PPAR-γ (Ly171883) reversed the inhibitions of NO release and lipid accumulation in the presence of calcitriol. The calcitriol-mediated viral suppression, inhibition of NO release and activation of VDR were partially blocked by an inhibitor of endoplasmic reticulum-associated degradation (ERAD), kifunensine. Furthermore, calcitriol blocked the HCV-induced expressions of apolipoprotein J and 78 kDa glucose-regulated protein, which was restored by pretreatment of kifunensine. These results indicated that the calcitriol-mediated HCV suppression was associated with the activation of VDR, interference with ERAD process, as well as blockades of PPAR, lipid accumulation and nitrative stress.

Vitamin D supplementation for chronic liver diseases in adults

BACKGROUND

Vitamin D deficiency is often reported in people with chronic liver diseases. Therefore, improving vitamin D status could have a beneficial effect on people with chronic liver diseases.

OBJECTIVES

To assess the beneficial and harmful effects of vitamin D supplementation in people with chronic liver diseases.

SEARCH METHODS

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, Science Citation Index Expanded, and Conference Proceedings Citation Index - Science. We also searched databases of ongoing trials and the World Health Organization International Clinical Trials Registry Platform. We scanned bibliographies of relevant publications and asked experts and pharmaceutical companies for additional trials. All searches were up to January 2017.

SELECTION CRITERIA

Randomised clinical trials that compared vitamin D at any dose, duration, and route of administration versus placebo or no intervention in adults with chronic liver diseases. Vitamin D could have been administered as supplemental vitamin D (vitamin D3 (cholecalciferol) or vitamin D2 (ergocalciferol)), or an active form of vitamin D (1α-hydroxyvitamin D (alfacalcidol), 25-hydroxyvitamin D (calcidiol), or 1,25-dihydroxyvitamin D (calcitriol)).

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by The Cochrane Collaboration. We contacted authors of the trials to ask for missing information. We conducted random-effects and fixed-effect meta-analyses. For dichotomous outcomes, we calculated risk ratios (RRs), and for continuous outcomes, we calculated mean differences (MD), both with 95% confidence intervals (CI) and Trial Sequential Analyses-adjusted CIs. We calculated Peto odds ratio (OR) for rare events. We considered risk of bias in domains to assess the risk of systematic errors. We conducted Trial Sequential Analyses to control the risk of random errors. We assessed the quality of the evidence with GRADE.

MAIN RESULTS

We included 15 randomised clinical trials with 1034 participants randomised. All trials had a parallel group design. Nine trials were conducted in high-income countries and six trials in middle-income countries. All trials were at high risk of bias. Six trials included participants with chronic hepatitis C, four trials included participants with liver cirrhosis, four trials included participants with non-alcoholic fatty liver disease, and one trial included liver transplant recipients. All included trials reported the baseline vitamin D status of participants. Participants in six trials had baseline 25-hydroxyvitamin D levels at or above vitamin D adequacy (20 ng/mL), while participants in the remaining nine trials were vitamin D insufficient (less than 20 ng/mL). All trials administered vitamin D orally. Mean duration of vitamin D supplementation was 0.5 years and follow-up was 0.6 years. Eleven trials (831 participants; 40% women; mean age 52 years) tested vitamin D3, one trial (18 men; mean age 61 years) with three intervention groups tested vitamin D2 and 25-dihydroxyvitamin D in separate groups, and three trials (185 participants; 55% women; mean age 55 years) tested 1,25-dihydroxyvitamin D. Seven trials used placebo, and eight trials used no intervention in the control group.The effect of vitamin D on all-cause mortality at the end of follow-up is uncertain because the results were imprecise (Peto OR 0.70, 95% CI 0.09 to 5.38; I2 = 32%; 15 trials; 1034 participants; very low quality evidence). Trial Sequential Analysis on all-cause mortality was performed based on a mortality rate in the control group of 10%, a relative risk reduction of 28% in the experimental intervention group, a type I error of 2.5%, and type II error of 10% (90% power). There was no diversity. The required information size was 6396 participants. The cumulative Z-curve did not cross the trial sequential monitoring boundary for benefit or harm after the 15th trial, and the Trial Sequential Analyses-adjusted CI was 0.00 to 2534.The effect of vitamin D on liver-related mortality (RR 1.62, 95% CI 0.08 to 34.66; 1 trial; 18 participants) and on serious adverse events such as hypercalcaemia (RR 5.00, 95% CI 0.25 to 100.8; 1 trial; 76 participants), myocardial infarction (RR 0.75, 95% CI 0.08 to 6.81; 2 trials; 86 participants), and thyroiditis (RR 0.33 95% CI 0.01 to 7.91; 1 trial; 68 participants) is uncertain because the results were imprecise. The evidence on all these outcomes is of very low quality. The effect of vitamin D3 on non-serious adverse events such as glossitis (RR 3.70, 95% CI 0.16 to 87.6; 1 trial; 65 participants; very low quality of evidence) is uncertain because the result was imprecise.Due to few data, we did not conduct Trial Sequential Analysis on liver-related mortality, and serious and non-serious adverse events.We found no data on liver-related morbidity and health-related quality of life in the randomised trials included in this review.

AUTHORS' CONCLUSIONS

We are uncertain as to whether vitamin D supplements in the form of vitamin D3, vitamin D2, 1,25-dihydroxyvitamin D, or 25-dihydroxyvitamin D have important effect on all-cause mortality, liver-related mortality, or on serious or non-serious adverse events because the results were imprecise. There is no evidence on the effect of vitamin D supplementation on liver-related morbidity and health-related quality of life. Our conclusions are based on few trials with an insufficient number of participants and on lack of data on clinically important outcomes. In addition, the analysed trials are at high risk of bias with significant intertrial heterogeneity. The overall quality of evidence is very low.

Comparison of Vitamin D Levels in Naive, Treated, and Inactive Carriers with Chronic Hepatitis B Virus

Background and Aims: During recent years, the relationship between vitamin D levels and chronic hepatitis B (CHB) infection has attracted many researchers' attention. However, the results relating to the association of vitamin D levels and HBV infection have been conflicting and there remains a lack of knowledge about the effects of antiviral treatments on vitamin D level. Methods: Eighty-four patients with CHB were assessed and divided into three groups: inactive carriers (n = 28), treated (n = 34), and new (treatment-naïve) cases (n = 22). Thirty-two healthy controls (HCs) were included to enable comparison with the CHB groups. The levels of vitamin D3 were measured and statistically compared among the various groups. Results: Male subjects had higher levels of vitamin D3 (41.25 vs 28.85, p < 0.01). No association was found among any of the groups when compared with the HC group. Despite the significant association, the HCs demonstrated a higher level of vitamin D3, which was lower in the treated group, the inactive carrier group, and the new cases group (new case [29.82] < inactive carrier [32.91] < treated [39.56] < control [44.88]). The HBV DNA levels were not associated with vitamin D3 levels in the inactive carriers (p = 0.171), the treated groups (p = 0.192), and the new cases (p = 0.369). Moreover, the alanine transaminase and aspartate transaminase levels were not associated with vitamin D3 levels for any of the HBV-infected groups. Conclusions: Vitamin D3 contributes to the clinical statues of CHB patients. There is also a possible correlation between clinically healthy CHB patients and vitamin D3 level.

New insight of vitamin D in chronic liver diseases

BACKGROUND

Vitamin D is a fat-soluble sterol derivative that is predominantly synthesized in the liver and has multiple functions. The accumulative data showed that the clinical manifestations and prognosis of chronic liver diseases are associated with serum vitamin D levels.

DATA SOURCES

A PubMed and Google Scholar search using terms: "vitamin D", "25(OH)D", "liver disease", "viral hepatitis", "non-alcoholic fatty liver disease", "liver fibrosis", "cirrhosis", "hepatocellular carcinoma" and "autoimmune liver disease" was performed, and relevant articles published in English between January 2000 and March 2014 were reviewed. Full-text publications relevant to the field were selected and relevant articles from reference lists were also included.

RESULTS

The insufficiency or deficiency of vitamin D is common in various kinds of chronic liver diseases including viral hepatitis B and C. Serum 25-hydroxyvitamin D and vitamin D receptors are possibly interrelated with the incidence, treatment and prognosis of diseases. Though the evidence of vitamin D supplementation in viral hepatitis and associated liver diseases is still limited, there is great potential to apply this adjuvant therapy to improve the treatments.

CONCLUSIONS

Although the exact role and mechanisms of vitamin D have not been fully elucidated in chronic liver diseases, it is potentially beneficial in the treatment of chronic liver diseases. Further mechanistic studies are needed to validate its clinical application.

Relationship between vitamin D and chronic liver diseases

Vitamin D is a fat-soluble vitamin with multiple biological effects that is predominantly synthetized in the liver. Various kinds of chronic liver diseases are associated with vitamin D deficiency, and vitamin D supplementation may influence treatment outcome. This article summarizes the role of vitamin D in the pathogenesis and treatment of chronic liver diseases to provide new insight into the treatment of these diseases.