Vitamin D and Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD): Novel Mechanistic Insights.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is an increasingly prevalent condition characterized by abnormal fat accumulation in the liver, often associated with metabolic disorders. Emerging evidence suggests a potential link between vitamin D deficiency and the development and progression of MASLD. The current review provides a concise overview of recent studies uncovering novel mechanistic insights into the interplay between vitamin D and MASLD. Several epidemiological studies have highlighted a significant association between low vitamin D levels and an increased risk of MASLD. Vitamin D, traditionally known for its role in bone health, has now been recognized as a key player in various physiological processes, including immune regulation and inflammation. Experimental studies using animal models have demonstrated that vitamin D deficiency exacerbates liver steatosis and inflammation, suggesting a potential protective role against MASLD. Mechanistically, vitamin D appears to modulate MASLD through multiple pathways. Firstly, the vitamin D receptor (VDR) is abundantly expressed in liver cells, indicating a direct regulatory role in hepatic function. Activation of the VDR has been shown to suppress hepatic lipid accumulation and inflammation, providing a mechanistic basis for the observed protective effects. Additionally, vitamin D influences insulin sensitivity, a critical factor in MASLD pathogenesis. Improved insulin sensitivity may mitigate the excessive accumulation of fat in the liver, thus attenuating MASLD progression. In parallel, vitamin D exhibits anti-inflammatory properties by inhibiting pro-inflammatory cytokines implicated in MASLD pathophysiology. Experimental evidence suggests that the immunomodulatory effects of vitamin D extend to the liver, reducing inflammation and oxidative stress, key drivers of MASLD, and the likelihood of hepatocyte injury and fibrosis. Understanding the complex interplay between vitamin D and MASLD provides a basis for exploring targeted therapeutic strategies and preventive interventions. As vitamin D deficiency is a modifiable risk factor, addressing this nutritional concern may prove beneficial in mitigating the burden of MASLD and associated metabolic disorders.

Successful therapy with tenofovir disoproxil fumarate (TDF) in patients with chronic hepatitis B (CHB) does not guarantee amelioration of liver damage assessing by transient elastography. A retrospective - prospective multicenter study.

BACKGROUND: Preventing disease progression and viral suppression are the main goals of antiviral therapy in chronic hepatitis B (CHB). Liver stiffness measurement (LSM) by transient elastography is a reliable non-invasive method to assess liver fibrosis in patients with CHB. Our aim was to explore factors that may affect changes in LSMs during long term tenofovir (TDF) monotherapy in a well characterized cohort of patients with compensated CHB. METHODS: We analyzed serial LSMs in 103 adult patients with CHB who were on TDF monotherapy and had at least three LSMs over a period of 90 months. RESULTS: Twenty-five (24%) patients had advanced fibrosis at baseline. A significant decline in mean LSM between baseline and last visit (8.7 ± 6.2 kPa vs. 6.7 ± 3.3, p = 10- 3) was observed. Twenty-four (23%) patients had progression of liver fibrosis with mean increase in liver stiffness of 2.8 kPa (range: 0.2-10.2 kPa). Multivariate analysis showed that BMI ≥ 25 (OR, 0.014; 95% CI, 0.001-0.157; p = 0.001) and advanced fibrosis (OR, 5.169; 95% CI, 1.240-21.540; p = 0.024) were independently associated with a fibrosis regression of > 30% of liver stiffness compared to baseline value. CONCLUSIONS: In CHB patients TDF monotherapy resulted in liver fibrosis regression, especially in patients with advanced fibrosis. Despite the successful antiviral effect of TDF, 1 out of 4 patients had liver fibrosis progression. Obesity and advanced fibrosis at baseline were independently associated with significant liver fibrosis regression.

Chimeric Antigen Receptor T Cell Therapy for Hepatocellular Carcinoma: Where Do We Stand?

Hepatocellular carcinoma (HCC) remains a global health challenge that urgently calls for innovative therapeutic strategies. Chimeric antigen receptor T cell (CAR T) therapy has emerged as a promising avenue for HCC treatment. However, the therapeutic efficacy of CAR T immunotherapy in HCC patients is significantly compromised by some major issues including the immunosuppressive environment within the tumor, antigen heterogeneity, CAR T cell exhaustion, and the advanced risk for on-target/off-tumor toxicity. To overcome these challenges, many ongoing preclinical and clinical trials are underway focusing on the identification of optimal target antigens and the decryption of the immunosuppressive milieu of HCC. Moreover, limited tumor infiltration constitutes a significant obstacle of CAR T cell therapy that should be addressed. The continuous effort to design molecular targets for CAR cells highlights the importance for a more practical approach for CAR-modified cell manufacturing. This review critically examines the current landscape of CAR T cell therapy for HCC, shedding light on the changes in innate and adaptive immune responses in the context of HCC, identifying potential CAR T cell targets, and exploring approaches to overcome inherent challenges. Ongoing advancements in scientific research and convergence of diverse treatment modalities offer the potential to greatly enhance HCC patients' care in the future.

Exploring the role of IL-1ß in inflammatory bowel disease pathogenesis.

Interleukin 1ß (IL-1ß) is a significant mediator of inflammation and tissue damage in IBD. The balance between IL-1ß and its endogenous inhibitor-IL-1Ra-, plays a critical role in both initiation and regulation of inflammation. However, the precise role of IL-1ß as a causative factor in IBD or simply a consequence of inflammation remains unclear. This review summarizes current knowledge on the molecular and cellular characteristics of IL-1ß, describes the existing evidence on the role of this cytokine as a modulator of intestinal homeostasis and an activator of inflammatory responses, and also discusses the role of microRNAs in the regulation of IL-1ß-related inflammatory responses in IBD. Current evidence indicates that IL-1ß is involved in several aspects during IBD as it greatly contributes to the induction of pro-inflammatory responses through the recruitment and activation of immune cells to the gut mucosa. In parallel, IL-1ß is involved in the intestinal barrier disruption and modulates the differentiation and function of T helper (Th) cells by activating the Th17 cell differentiation, known to be involved in the pathogenesis of IBD. Dysbiosis in the gut can also stimulate immune cells to release IL-1ß, which, in turn, promotes inflammation. Lastly, increasing evidence pinpoints the central role of miRNAs involvement in IL-1ß-related signaling during IBD, particularly in the maintenance of homeostasis within the intestinal epithelium. In conclusion, given the crucial role of IL-1ß in the promotion of inflammation and immune responses in IBD, the targeting of this cytokine or its receptors represents a promising therapeutic approach. Further research into the IL-1ß-associated post-transcriptional modifications may elucidate the intricate role of this cytokine in immunomodulation.

Adrenal insufficiency in liver diseases - pathophysiology and underlying mechanisms.

Relative adrenal insufficiency (RAI) is common in critically ill patients with cirrhosis, but it has been also documented in non-critically ill patients. Its pathophysiology is complex and not well understood yet. In this review, we aimed to present potential mechanisms and causal pathways implicated in the pathogenesis of RAI in cirrhosis. There is accumulating evidence supporting a suboptimal baseline adrenal function in cirrhosis mainly due to decreased cortisol synthesis and metabolism rates from the adrenal gland. Apart from this peripheral impairment, more recent studies suggest that there is a greater defect in the central stimulation of the hypothalamic-pituitary-adrenal (HPA) axis (hypothalamus/pituitary gland). Pro-inflammatory mediators, which are elevated in cirrhosis, have been also implicated through suppression of the HPA axis, decrease in cortisol synthesis and tissue glucocorticoid resistance. All abovementioned support the hepatoadrenal syndrome hypothesis that during episodes of acute decompensation there is suboptimal adrenocortical response that leads to worse outcomes. In conclusion, the complex pathophysiology of adrenal dysfunction in cirrhosis has not been fully elucidated yet and further research is needed in order to better understand this rather common entity in cirrhosis.

Low Urinary Free Cortisol as a Risk Factor for Patients with Variceal Bleeding.

Background and Objectives: Specificity and reliability issues of the current cortisol assessment methods lead to limitations on the accurate assessment of relative adrenal insufficiency. Although free cortisol provides a more accurate evaluation of adrenal cortisol production, the expense and time-consuming nature of these assays make them impractical for routine use. Research has, thus, focused on alternative methods, such as indirectly measuring free cortisol using Coolens' equation or directly assessing salivary cortisol concentration, which is considered a more favorable approach despite associated challenges like sampling issues and infection risks. The aim of this study was to explore correlations between 24 h urinary free cortisol (UFC), free plasma cortisol, serum total cortisol, and salivary cortisol as potential reliable indices of free cortisol in the setting of variceal bleeding. Additionally, we assessed the predictive value of UFC for 6-week mortality and 5-day treatment failure in patients with liver cirrhosis and variceal bleeding. Materials and Methods: A total of 40 outpatients with liver cirrhosis and variceal bleeding were enrolled. Free cortisol levels in serum, saliva, and urine were assessed using the electrochemiluminescence immunoassay method. For the measurement of plasma-free cortisol, a single quadrupole mass spectrometer was employed. The quantification of free cortisol was fulfilled by analyzing the signal response in the negative ESI-MS mode. Results: UFC was significantly correlated to free plasma cortisol. Negative correlations were demonstrated between UFC, the Child-Pugh (CP) score, and C reactive protein (CRP) levels. In the multivariate analysis, CP stage C was associated with 6-week mortality risk and portal vein thrombosis with 5-day treatment failure using Cox regression and binary logistic regression analyses, respectively. Patients who experienced rebleeding, infection, or death (or any combination of these events) presented with lower levels of UFC. Conclusions: This study suggests that low levels of UFC may impose a risk factor for patients with liver cirrhosis and variceal bleeding. The use of UFC as an index of adrenal cortisol production in variceal bleeding warrants further investigation.

Epigenetic Regulation in Lean Nonalcoholic Fatty Liver Disease.

Nonalcoholic fatty liver disease (NAFLD), the most prominent cause of chronic liver disease worldwide, is a rapidly growing epidemic. It consists of a wide range of liver diseases, from steatosis to nonalcoholic steatohepatitis, and predisposes patients to liver fibrosis, cirrhosis, and even hepatocellular carcinoma. NAFLD is strongly correlated with obesity; however, it has been extensively reported among lean/nonobese individuals in recent years. Although lean patients demonstrate a lower prevalence of diabetes mellitus, central obesity, dyslipidemia, hypertension, and metabolic syndrome, a percentage of these patients may develop steatohepatitis, advanced liver fibrosis, and cardiovascular disease, and have increased all-cause mortality. The pathophysiological mechanisms of lean NAFLD remain vague. Studies have reported that lean NAFLD demonstrates a close association with environmental factors, genetic predisposition, and epigenetic modifications. In this review, we aim to discuss and summarize the epigenetic mechanisms involved in lean NAFLD and to introduce the interaction between epigenetic patterns and genetic or non genetic factors. Several epigenetic mechanisms have been implicated in the regulation of lean NAFLD. These include DNA methylation, histone modifications, and noncoding-RNA-mediated gene regulation. Epigenetics is an area of special interest in the setting of lean NAFLD as it could provide new insights into the therapeutic options and noninvasive biomarkers that target this under-recognized and challenging disorder.

Alexithymic characteristics and interoceptive abilities are associated with disease severity and levels of C-reactive protein and cytokines in patients with inflammatory bowel disease.

Background: Alexithymia and atypical gut-brain signaling have been linked to the pathophysiology of inflammatory bowel disease (IBD). We herein assessed IBD patients' alexithymia levels and interoceptive abilities, and detected potential correlations with psychological distress, symptom severity and disease activity, and inflammation indices. Methods: Adult IBD outpatients and healthy controls were recruited. Alexithymia was assessed using the Toronto Alexithymia Scale, interoceptive accuracy using the Heartbeat Counting Test (cardiac interoception) and the Water Load Test-II (gastric interoception), and interoceptive sensibility using the Multidimensional Assessment of Interoceptive Awareness (MAIA). Results: Forty-one patients with Crohn's disease (CD), 16 with ulcerative colitis (UC), and 50 healthy controls were included. In CD patients, the level of externally oriented thinking and total alexithymia score were correlated with disease activity (P=0.027 and P=0.047, respectively), while in UC patients difficulties in identifying emotions were linked to disease activity (P=0.007). In CD patients, the Noticing, Not-Worrying and Emotional Awareness MAIA subscale score were correlated with C-reactive protein levels (P=0.005, P=0.048 and P=0.005), the Noticing subscale score with interleukin (IL)-1ß levels (r=-0.350, P=0.039), the Not-Distracting subscale score with IL-6 levels (r=-0.402, P=0.017), and the Emotional Awareness subscale score with IL-1ß (r=-0.367, P=0.030) and IL-6 (r=-0.379, P=0.025) levels. Finally, in UC patients, the Not-Worrying subscale score was significantly associated with IL-6 levels (r=-0.532, P=0.049), while difficulties in identifying emotions were linked to IL-8 levels (r=0.604, P=0.022). Conclusion: Emotional and interoceptive processing is associated with IBD disease activity, suggesting a potential implication for IBD pathophysiology.

The Influence of Single Nucleotide Polymorphisms on Vitamin D Receptor Protein Levels and Function in Chronic Liver Disease.

Single nucleotide polymorphisms (SNPs) in the vitamin D receptor (VDR) gene have been associated with chronic liver disease. We investigated the role of VDR SNPs on VDR protein levels and function in patients with chronic liver disease. VDR expression levels were determined in peripheral T lymphocytes (CD3+VDR+), monocytes (CD14+VDR+), and plasma from patients (n = 66) and healthy controls (n = 38). Genotyping of SNPs and the determination of expression of VDR/vitamin D-related genes were performed by using qPCR. The effect of FokI SNP on vitamin D-binding to VDR was investigated by molecular dynamics simulations. CD14+VDR+ cells were correlated with the MELD score. The ApaI SNP was associated with decreased CD3+VDR+ levels in cirrhotic patients and with higher liver stiffness in HCV patients. The BsmI and TaqI SNPs were associated with increased VDR plasma concentrations in cirrhotic patients and decreased CD14+VDR+ levels in HCV patients. The FokI SNP was associated with increased CD3+VDR+ levels in cirrhotic patients and controls. VDR polymorphisms were significantly related to the expression of genes critical for normal hepatocyte function and immune homeostasis. VDR expression levels were related to the clinical severity of liver disease. VDR SNPs may be related to the progression of chronic liver disease by affecting VDR expression levels.

Creeping Fat in Crohn's Disease-Surgical, Histological, and Radiological Approaches.

During the course of Crohn's disease, the response of mesenteric adipose tissue to the production of inflammatory mediators and bacterial invasion through the intestinal mucosa results in the formation of creeping fat. Creeping fat describes the arresting finger-like projections that surround the inflamed bowel. In this review, the microscopic and macroscopic features of creeping fat and histological evidence for the importance of this tissue are discussed. Moreover, the most recent insights into the radiological assessment of creeping fat in patients with Crohn's disease are reported. Advances in imaging techniques have revolutionized the possibility of visualization and quantification of adipose tissue depots with excellent accuracy. Visceral fat has been significantly correlated with various Crohn's-disease-related outcomes. Despite the difficulties in distinguishing physiologic perienteric fat from creeping fat, the growing interest in fat-wrapping in Crohn's disease has rejuvenated radiologic research. With regard to the noninvasive fat-wrapping assessment, a novel CT enterography-based mesenteric creeping fat index has been developed for the mitigation of the confounding effect of normal retroperitoneal and perienteric adipose tissue. Research on machine learning algorithms and computational radiomics in conjunction with mechanistic studies may be the key for the elucidation of the complex role of creeping fat in Crohn's disease.

Exploring the Role of Vitamin D and the Vitamin D Receptor in the Composition of the Gut Microbiota.

The microbiome has a major impact on human physiology and plays a critical role in enhancing or impairing various physiological functions such as regulation of the immune system, metabolic activities, and biosynthesis of vitamins and hormones. Variations in the gut microbial community play a critical role in both health and disease. Regulation of calcium and bone metabolism, as well as cellular functions such as proliferation, apoptosis, differentiation, and immune modulation, are among the known effects of vitamin D. These biological functions are primarily carried out through the binding of vitamin D to the vitamin D receptor (VDR), a member of the nuclear receptor superfamily. The immunomodulatory properties of vitamin D suggest that this molecule plays an important role in various diseases. Maintenance of immune homeostasis appears to occur in part through the interaction of the gut microbiota with vitamin D. Increasing evidence points to the central role of vitamin D in maintaining mucosal barrier function, as vitamin D deficiency has been associated with disruption of gut barrier integrity, translocation of bacteria into the bloodstream, and systemic inflammation. In parallel, a bidirectional interaction between vitamin D and the gut microbiota has been demonstrated as data show upregulation of intestinal VDR expression and downregulation of inflammatory markers in response to fermentation products. The aim of this review is to provide an overview of the evidence of a link between the gut microbiome and vitamin D, with a focus on data from experimental models and translational data from human studies related to vitamin D-induced changes in gut microbiota composition.

HERACLIS-HDV cohort for the factors of underdiagnosis and prevalence of hepatitis D virus infection in HBsAg-positive patients.

BACKGROUND AND AIMS: Hepatitis D virus (HDV) underdiagnosis remains common. We assessed the HDV screening and prevalence rates in HBsAg-positive patients seen at tertiary liver centres throughout Greece as well as factors affecting HDV diagnosis. METHODS: All adult HBsAg-positive patients seen within the last 5 years were included. Non-screened patients who visited or could be recalled to the clinics over a 6-month period were prospectively tested for anti-HDV. RESULTS: Of 5079 HBsAg-positive patients, 53% had anti-HDV screening (41% before and 12% after study initiation). Pre-study (8%-88%) and total screening rates (14%-100%) varied widely among centres. Screening rates were associated with older age, known risk group, elevated ALT, centre location and size and period of first visit. Anti-HDV prevalence was 5.8% without significant difference in patients screened before (6.1%) or after study initiation (4.7%, p = 0.240). Anti-HDV positivity was associated with younger age, parenteral drug use, born abroad, advanced liver disease and centre location. Overall, HDV RNA detectability rate was 71.6% being more frequent in anti-HDV-positive patients with elevated ALT, advanced liver disease and hepatitis B therapy. CONCLUSIONS: Anti-HDV screening rates and recall capabilities vary widely among Greek liver clinics being higher in HBsAg-positive patients of known risk group with active/advanced liver disease seen at smaller centres, while non-medical factors are also important. Anti-HDV prevalence varies throughout Greece being higher in patients born abroad with younger age, parenteral drug use and advanced liver disease. Viremia is more frequently but not exclusively detected in anti-HDV-positive patients with elevated ALT and advanced liver disease.

Creeping Fat in the Pathogenesis of Crohn's Disease: An Orchestrator or a Silent Bystander?

Although the phenomenon of hypertrophied adipose tissue surrounding inflamed bowel segments in Crohn's disease has been described since 1932, the mechanisms mediating the creeping fat formation and its role in the pathogenesis of the disease have not been fully unraveled. Recent advances demonstrating the multiple actions of adipose tissue beyond energy storage have brought creeping fat to the forefront of scientific research. In Crohn's disease, dysbiosis and transmural injury compromise the integrity of the intestinal barrier, resulting in an excessive influx of intraluminal microbiota and xenobiotics. The gut and peri-intestinal fat are in close anatomic relationship, implying a direct reciprocal immunologic relationship, whereas adipocytes are equipped with an arsenal of innate immunity sensors that respond to invading stimuli. As a result, adipocytes and their progenitor cells undergo profound immunophenotypic changes, leading to adipose tissue remodeling and eventual formation of creeping fat. Indeed, creeping fat is an immunologically active organ that synthesizes various pro- and anti-inflammatory cytokines, profibrotic mediators, and adipokines that serve as paracrine/autocrine signals and regulate immune responses. Therefore, creeping fat appears to be involved in inflammatory signaling, which explains why it has been associated with a higher severity or complicated phenotype of Crohn's disease. Interestingly, there is growing evidence for an alternative immunomodulatory function of creeping fat as a second barrier that prevents an abnormal systemic inflammatory response at the expense of an increasingly proliferating profibrotic environment. Further studies are needed to clarify how this modified adipose tissue exerts its antithetic effect during the course of Crohn's disease.

Creeping fat, a common feature of Crohn's disease, is the wrapping of mesenteric fat around the intestinal wall, resulting in mucosal response aggravation and lesion exacerbation through releasing pro-inflammatory molecules and cells to the gut, leading to worsened disease course.

Gene Polymorphisms and Biological Effects of Vitamin D Receptor on Nonalcoholic Fatty Liver Disease Development and Progression.

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, with increasing prevalence worldwide. The genetic and molecular background of NAFLD pathogenesis is not yet clear. The vitamin D/vitamin D receptor (VDR) axis is significantly associated with the development and progression of NAFLD. Gene polymorphisms may influence the regulation of the VDR gene, although their biological significance remains to be elucidated. VDR gene polymorphisms are associated with the presence and severity of NAFLD, as they may influence the regulation of adipose tissue activity, fibrosis, and hepatocellular carcinoma (HCC) development. Vitamin D binds to the hepatic VDR to exert its biological functions, either by activating VDR transcriptional activity to regulate gene expression associated with inflammation and fibrosis or by inducing intracellular signal transduction through VDR-mediated activation of Ca2+ channels. VDR activity has protective and detrimental effects on hepatic steatosis, a characteristic feature of NAFLD. Vitamin D-VDR signaling may control the progression of NAFLD by regulating immune responses, lipotoxicity, and fibrogenesis. Elucidation of the genetic and molecular background of VDR in the pathophysiology of NAFLD will provide new therapeutic targets for this disease through the development of VDR agonists, which already showed promising results in vivo.

The Inflammatory Bowel Disease-Disk Tool for Assessing Disability in Inflammatory Bowel Disease Patients: Validation of the Greek Version.

BACKGROUND: The Inflammatory Bowel Disease-Disk (IBD-Disk) is a physician-administered tool that evaluates the functional status of patients with Inflammatory Bowel Disease (IBD). The aim of our study was to validate the content of the IBD-Disk in a Greek cohort of IBD patients. METHODS: Two questionnaires [the IBD Disk and the IBD-Disability Index (IBD-DI)] were translated into Greek and administered to IBD patients at baseline visit, after 4 weeks and 6 months. Validation of the IBD Disk included measuring of concurrent validity, reproducibility, and internal consistency. RESULTS: A total of 300 patients were included at baseline and 269 at follow-up. There was a good correlation between the total scores of the IBD-Disk and IBD-DI at baseline (Pearson correlation 0.87, p < 0.001). Reproducibility of the total IBD-Disk score was very good [intra-class correlation coefficient (ICC), 95% confidence interval (CI) 0.89 (0.86-0.91)]. Cronbach's coefficient alpha for all items achieved 0.90 (95%CI 0.88-0.92), demonstrating a very good homogeneity of the IBD-Disk items. Female gender and extraintestinal manifestations were significantly associated with a higher IBD-Disk total score. CONCLUSIONS: The Greek version of the IBD-Disk proved to be a reliable and valid tool in detecting and assessing IBD-related disability in a Greek cohort of IBD patients.

Intestinal barrier dysfunction as a key driver of severe COVID-19.

The intestinal lumen harbors a diverse consortium of microorganisms that participate in reciprocal crosstalk with intestinal immune cells and with epithelial and endothelial cells, forming a multi-layered barrier that enables the efficient absorption of nutrients without an excessive influx of pathogens. Despite being a lung-centered disease, severe coronavirus disease 2019 (COVID-19) affects multiple systems, including the gastrointestinal tract and the pertinent gut barrier function. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can inflict either direct cytopathic injury to intestinal epithelial and endothelial cells or indirect immune-mediated damage. Alternatively, SARS-CoV-2 undermines the structural integrity of the barrier by modifying the expression of tight junction proteins. In addition, SARS-CoV-2 induces profound alterations to the intestinal microflora at phylogenetic and metabolomic levels (dysbiosis) that are accompanied by disruption of local immune responses. The ensuing dysregulation of the gut-lung axis impairs the ability of the respiratory immune system to elicit robust and timely responses to restrict viral infection. The intestinal vasculature is vulnerable to SARS-CoV-2-induced endothelial injury, which simultaneously triggers the activation of the innate immune and coagulation systems, a condition referred to as "immunothrombosis" that drives severe thrombotic complications. Finally, increased intestinal permeability allows an aberrant dissemination of bacteria, fungi, and endotoxin into the systemic circulation and contributes, to a certain degree, to the over-exuberant immune responses and hyper-inflammation that dictate the severe form of COVID-19. In this review, we aim to elucidate SARS-CoV-2-mediated effects on gut barrier homeostasis and their implications on the progression of the disease.

Alterations in gut immunological barrier in SARS-CoV-2 infection and their prognostic potential.

Although coronavirus disease 2019 (COVID-19) is primarily associated with mild respiratory symptoms, a subset of patients may develop more complicated disease with systemic complications and multiple organ injury. The gastrointestinal tract may be directly infected by SARS-CoV-2 or secondarily affected by viremia and the release of inflammatory mediators that cause viral entry from the respiratory epithelium. Impaired intestinal barrier function in SARS-CoV-2 infection is a key factor leading to excessive microbial and endotoxin translocation, which triggers a strong systemic immune response and leads to the development of viral sepsis syndrome with severe sequelae. Multiple components of the gut immune system are affected, resulting in a diminished or dysfunctional gut immunological barrier. Antiviral peptides, inflammatory mediators, immune cell chemotaxis, and secretory immunoglobulins are important parameters that are negatively affected in SARS-CoV-2 infection. Mucosal CD4+ and CD8+ T cells, Th17 cells, neutrophils, dendritic cells, and macrophages are activated, and the number of regulatory T cells decreases, promoting an overactivated immune response with increased expression of type I and III interferons and other proinflammatory cytokines. The changes in the immunologic barrier could be promoted in part by a dysbiotic gut microbiota, through commensal-derived signals and metabolites. On the other hand, the proinflammatory intestinal environment could further compromise the integrity of the intestinal epithelium by promoting enterocyte apoptosis and disruption of tight junctions. This review summarizes the changes in the gut immunological barrier during SARS-CoV-2 infection and their prognostic potential.

Treatment of portal vein thrombosis in cirrhosis: a multicenter real life cοhort study.

BACKGROUND: Portal vein thrombosis (PVT) is a common complication of cirrhosis and can be a cause or consequence of liver disease progression. It is unclear whether PVT treatment is affecting clinical outcomes in cirrhotics. METHODS: This is a multicenter study of cirrhotics with PVT, initially retrospectively and thereafter prospectively registered in a data base. We studied the impact of PVT treatment on this population for efficacy, safety and the impact on survival. In survival analysis Mantel-Cox and Wilcoxon-Breslow-Gehan tests were used. A P value of <0.05, was considered significant. For statistical computations the STATA 12.1 was used. RESULTS: Seventy-six patients were included (76% decompensated, median MELD score 12 and Child-Pugh score 7), 47% with concomitant HCC. Fifty-one patients with PVT were treated with Vitamin-K antagonists or Low-Molecular-Weight Heparin. Patients were followed up for at least 6 months after PVT diagnosis, or until death or transplantation. PV patency after 6 months was not statistically different between patients receiving or not anticoagulation (complete-partial recanalization 27.4% of treated vs. 20% of untreated, P=0.21). Median survival was statistically worse between patients treated with anticoagulation than those untreated (10 vs. 15 months, P=0.036). Less portal hypertensive bleeding and less decompensation rates were found in treated cirrhotics vs. untreated (45.8% vs. 54.2%, P=0.003 and 78% vs. 80.9%, P=0.78, respectively). Patients with HCC had worse survival when treated vs. untreated (P=0.047). CONCLUSIONS: In our cohort of cirrhotics with PVT, treatment was feasible with acceptable side effects, but without meaningful clinical benefits.

Vitamin D and Microbiome: Molecular Interaction in Inflammatory Bowel Disease Pathogenesis.

Studies of systemic autoimmune diseases point to characteristic microbial patterns in various diseases, including inflammatory bowel disease (IBD). Autoimmune diseases, and IBD in particular, show a predisposition to vitamin D deficiency, leading to alterations in the microbiome and disruption of intestinal epithelial barrier integrity. This review examines the role of the gut microbiome in IBD and discusses how vitamin D-vitamin D receptor (VDR)-associated molecular signaling pathways contribute to the development and progression of IBD through their effects on gut barrier function, the microbial community, and immune system function. The present data demonstrate that vitamin D promotes the proper function of the innate immune system by acting as an immunomodulator, exerting anti-inflammatory effects, and critically contributing to the maintenance of gut barrier integrity and modulation of the gut microbiota, mechanisms that may influence the IBD development and progression. VDR regulates the biological effects of vitamin D and is related to environmental, genetic, immunologic, and microbial aspects of IBD. Vitamin D influences the distribution of the fecal microbiota, with high vitamin D levels associated with increased levels of beneficial bacterial species and lower levels of pathogenic bacteria. Understanding the cellular functions of vitamin D-VDR signaling in intestinal epithelial cells may pave the way for the development of new treatment strategies for the therapeutic armamentarium of IBD in the near future.

miRNA Molecules-Late Breaking Treatment for Inflammatory Bowel Diseases?

MicroRNAs (miRNAs) are a group of non-coding RNAs that play a critical role in regulating epigenetic mechanisms in inflammation-related diseases. Inflammatory bowel diseases (IBDs), which primarily include ulcerative colitis (UC) and Crohn's disease (CD), are characterized by chronic recurrent inflammation of intestinal tissues. Due to the multifactorial etiology of these diseases, the development of innovative treatment strategies that can effectively maintain remission and alleviate disease symptoms is a major challenge. In recent years, evidence for the regulatory role of miRNAs in the pathogenetic mechanisms of various diseases, including IBD, has been accumulating. In light of these findings, miRNAs represent potential innovative candidates for therapeutic application in IBD. In this review, we discuss recent findings on the role of miRNAs in regulating inflammatory responses, maintaining intestinal barrier integrity, and developing fibrosis in clinical and experimental IBD. The focus is on the existing literature, indicating potential therapeutic application of miRNAs in both preclinical experimental IBD models and translational data in the context of clinical IBD. To date, a large and diverse data set, which is growing rapidly, supports the potential use of miRNA-based therapies in clinical practice, although many questions remain unanswered.