Published papers

© 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature. Aims/hypothesis: Accumulation of adipose tissue macrophages is considered pivotal in the development of obesity-associated inflammation and insulin resistance. In addition, recent studies suggest an involvement of the intestine as the primary organ in inducing hyperglycaemia and insulin resistance. We have reported that the C-C motif chemokine receptor (CCR) CCR9 is associated with intestinal immunity and has a pathogenic role in various liver diseases. However, its contribution to type 2 diabetes is unknown. In the current study, we aimed to clarify the involvement of CCR9 in the pathology of type 2 diabetes and the potential underlying mechanisms. Methods: To elucidate how CCR9 affects the development of metabolic phenotypes, we examined the impact of CCR9 deficiency on the pathogenesis of type 2 diabetes using male C57BL/6J (wild-type [WT]) and CCR9-deficient (CCR9 knockout [KO]) mice fed a 60% high-fat diet (HFD) for 12 weeks. Results: WT and Ccr9KO mice fed an HFD exhibited a comparable weight gain; however, glucose tolerance and insulin resistance were significantly improved in Ccr9KO mice. Moreover, visceral adipose tissue (VAT) and the liver of Ccr9KO mice presented with less inflammation and increased expression of glucose metabolism-related genes than WT mice. Ccr9 and Ccl25 expression were specifically higher in the small intestine but was not altered by HFD feeding and type 2 diabetes development. Accumulation of IFN-γ-producing CD4+ T lymphocytes and increased intestinal permeability in the small intestine was observed in WT mice following HFD feeding, but these changes were suppressed in HFD-fed Ccr9KO mice. Adoptive transfer of gut-tropic CCR9-expressing T lymphocytes partially reversed the favourable glucose tolerance found in Ccr9KO mice via exacerbated inflammation in the small intestine and VAT. Conclusions/interpretation: CCR9 plays a central role in the pathogenesis of type 2 diabetes by inducing an inflammatory shift in the small intestine. Our findings support CCR9 as a new therapeutic target for type 2 diabetes via the gut–VAT–liver axis. Graphical abstract: [Figure not available: see fulltext.]

BACKGROUND AND AIMS: The number of patients with non-alcoholic steatohepatitis (NASH) is increasing globally. Recently, specific chemokine receptors have become an area of interest for designing NASH therapeutic targets. This is the first report to examine the role of the C-C chemokine receptor 9 (CCR9)/C-C chemokine receptor ligand 25 (CCL25) axis, and to reveal its therapeutic potential against NASH progression METHODS: Patients with biopsy-proven non-alcoholic liver disease (NAFLD) were recruited and their serum and hepatic chemokine expression was examined. Furthermore, Wild type (WT) and CCR9(-/-) mice were fed a high-fat high-cholesterol (HFHC) diet for 24 weeks to establish NASH RESULTS: The serum CCL25, and hepatic CCR9 and CCL25 expression levels increased in patients with NASH compared to healthy volunteers. Furthermore, CCR9(-/-) mice were protected from HFHC diet-induced NASH progression both serologically and histologically. Flow cytometry and immunohistochemistry analysis identified CCR9(+)CD11b(+) inflammatory macrophages accumulated in the inflamed livers of HFHC diet-fed mice, while the number was reduced in CCR9(-/-) mice. Consistent with human NASH livers, CCR9 was also expressed on hepatic stellate cells (HSCs) in NASH-developed mice, while CCR9 deficient HSCs showed less fibrogenic potential in vitro. Administration of CCR9 antagonist hampered further fibrosis progression in NASH-developed mice, supporting its potential clinical application. Finally, we showed that CCR9 blockade attenuated the development of NAFLD-related hepatocellular carcinoma in mice injected with diethylnitrosamine under HF diet CONCLUSIONS: These results highlight the role of the CCR9/CCL25 axis on macrophage recruitment and fibrosis formation in a murine NASH model, providing new insights into therapeutic strategies for NASH.

Increased intestinal permeability and hepatic macrophage activation by endotoxins are involved in alcohol-induced liver injury pathogenesis. Long-term alcohol exposure conversely induces endotoxin immune tolerance; however, the precise mechanism and reversibility are unclear. Seventy-two alcohol-dependent patients with alcohol dehydrogenase-1B (ADH1B, rs1229984) and aldehyde dehydrogenase-2 (ALDH2, rs671) gene polymorphisms admitted for alcohol abstinence were enrolled. Blood and fecal samples were collected on admission and 4 weeks after alcohol cessation and were sequentially analyzed. Wild-type and ALDH2*2 transgenic mice were used to examine the effect of acetaldehyde exposure on liver immune responses. The productivity of inflammatory cytokines of peripheral CD14+ monocytes in response to LPS stimulation was significantly suppressed in alcohol dependent patients on admission relative to that in healthy controls, which was partially restored by alcohol abstinence with little impact on the gut microbiota composition. Notably, immune suppression was associated with ALDH2/ADH1B gene polymorphisms, and patients with a combination of ALDH2*1/*2 and ADH1B*2 genotypes, the most acetaldehyde-exposed group, demonstrated a deeply suppressed phenotype, suggesting a direct role of acetaldehyde. In vitro LPS and malondialdehyde-acetaldehyde adducted protein stimulation induced direct cytotoxicity on monocytes derived from healthy controls, and a second LPS stimulation suppressed the inflammatory cytokines production. Consistently, hepatic macrophages of ethanol-administered ALDH2*2 transgenic mice exhibited suppressed inflammatory cytokines production in response to LPS compared to that in wild-type mice, reinforcing the contribution of acetaldehyde to liver macrophage function. These results collectively provide new perspectives on the systemic influence of excessive alcohol consumption based on alcohol-metabolizing enzyme genetic polymorphisms.

Plasmacytoid dendritic cells (pDCs) perform dual proinflammatory and immunosuppressive roles. We recently reported the potential of pDC therapy for treatment of intractable acute liver failure. However, establishment of efficient methods to deliver pDCs to the liver is essential for future clinical therapeutic applications. The present study demonstrates a higher abundance of liver and peripheral blood pDCs in mice lacking C-C motif chemokine receptor 9 (CCR9), a pDC gut-homing receptor, than in WT mice. Adoptive transfer of Ccr9–/– pDCs resulted in a higher efficiency of migration to the liver than WT pDCs did, while WT pDCs migrated efficiently to the original target organ, the small intestine. Further, Ccr9–/– pDCs consistently migrated efficiently to livers with concanavalin A–induced inflammation, and exerted a more effective immunosuppressive effect, resulting in better protection against acute liver inflammation than that demonstrated by WT pDCs. These findings highlight the therapeutic potential of the manipulation of the CCR9 axis as an approach to improve migration of immunosuppressive pDCs to the liver in order to exploit their beneficial effects in acute liver disease.

Non-alcoholic steatohepatitis (NASH) is a leading cause of chronic liver disease that can progress to liver fibrosis. Recent clinical advance suggests a reversibility of liver fibrosis, but the cellular and molecular mechanisms underlying NASH resolution remain unclarified. Here, using a murine diet-induced NASH and the subsequent resolution model, we demonstrate direct roles of CD8+ tissue-resident memory CD8+ T (CD8+ Trm) cells in resolving liver fibrosis. Single-cell transcriptome analysis and FACS analysis revealed CD69+CD103−CD8+ Trm cell enrichment in NASH resolution livers. The reduction of liver CD8+ Trm cells, maintained by tissue IL-15, significantly delayed fibrosis resolution, while adoptive transfer of these cells protected mice from fibrosis progression. During resolution, CD8+ Trm cells attracted hepatic stellate cells (HSCs) in a CCR5-dependent manner, and predisposed activated HSCs to FasL-Fas-mediated apoptosis. Histological assessment of patients with NASH revealed CD69+CD8+ Trm abundance in fibrotic areas, further supporting their roles in humans. These results highlight the undefined role of liver CD8+ Trm in fibrosis resolution.

The precise manipulation of immune tolerance is the holy grail of immunotherapies for both autoimmunity and cancer immunity. Thymomas are well known to be associated with autoimmune diseases. The exact mechanism by which autoreactivity is induced after thymectomy remains to be elucidated. We herein present the case of a 50-year-old lady with concurrent de novo type 1 autoimmune hepatitis (AIH) and pure red cell aplasia (PRCA), 1 month after undergoing a successful total thymectomy for combined squamous cell carcinoma and thymoma (Masaoka stage II). Corticosteroids yielded short-term effects for both AIH and PRCA. Literature on thymoma-associated AIH, an extremely rare immune-related comorbidity, was also reviewed.

Background Liver fibrosis is one of the cardinal clinical features of chronic hepatitis C (CHC). However, the mechanisms underlying the evolution and reversion of liver fibrosis after hepatitis C virus (HCV) eradication and their relationship with clinical outcomes and metabolic alterations are not fully elucidated. Whether any non-invasive fibrosis marker can predict prognosis is unknown. Methods Between October 2014 and September 2019, 418 patients with CHC or compensated cirrhosis with HCV were prospectively recruited in this observational study. 326 patients that were successfully eradicated with interferon-free direct antiviral agents (IFN-free DAAs) were analyzed. Peri-treatment dynamics of serum levels of type IV collagen 7S fragment (4COL7S), a fibrosis marker, and subsequent clinical outcomes, including hepatic decompensation, newly emerged hepatocellular carcinoma (HCC), and all-cause mortality were analyzed. Results Ten (3.1%) patients died during the observation period. 4COL7S-defined fibrosis progression (n = 97, 29.8%) at SVR was significantly correlated with worse all-cause mortality post-SVR (P = 0.0062) but not with the probability of newly emerged HCC (P = 0.24). Prognostic tendency was more prominent in patients with advanced fibrosis (P< 0.0001). 4COL7S-defined fibrosis progression at SVR and a baseline platelet count less than 10×104/μL were significantly predicted all-cause mortality (P = 0.0051). In exploratory analyses, a decreased 4COL7S at the end of treatment was correlated with a matrix-degrading phenotype that showed higher serum metalloproteinase to tissue inhibitors of metalloproteinase-1 ratios and characteristic metabolic fingerprints such as increased butyrate, some medium-chain fatty acids, anabolic amino acids, and decreased uremia toxins. Conclusions Peri-treatment dynamics of serum 4COL7S, a non-invasive fibrosis marker, predict prognosis. Non-invasive fibrosis markers may be useful biomarkers for risk stratification post-SVR.

A brief intervention is often effective for patients with mild alcohol use disorder (AUD), but it is not effective for most patients with severe AUD or alcohol dependence to reduce alcohol intake. Nalmefene (Selincro®), an opioid receptor modulator, was approved in Japan in 2019. Nalmefene was administered to 18 outpatients with alcohol-related liver diseases. Five patients stopped coming to the hospital without notice, and two patients stopped taking medicine due to dizziness. Thus, 11 patients were noted to have reduced amount of alcohol intake at 24 weeks of using nalmefene. However, one of these patients was referred to a hospital specializing in alcohol dependence thereafter. Thus, the use of nalmefene provides a new concept for AUD treatment (i. e., alcohol intake reduction). However, some adverse events are noted, such as nausea and dizziness. Therefore, physicians with more experience with AUD treatment should use the drugma.

How liver tolerance is disrupted in immune-mediated liver injury is currently unclear. There is also insufficient information available regarding susceptibility, precipitation, escalation, and perpetuation of autoimmune hepatitis. To explore how dietary fiber influences hepatic damage, we applied the concanavalin A (ConA)-induced acute immune-mediated liver injury model in mice fed a diet supplemented with 6.8% inulin, a water-soluble fermentable fiber. Twelve hours after ConA administration, inulin-supplemented diet-fed mice demonstrated significantly alleviated hepatic damage histologically and serologically, with down-regulation of hepatic interferon-γ and tumor necrosis factor and reduced myeloperoxidase (MPO)-producing neutrophil infiltration. Preconditioning with an inulin-supplemented diet for 2 weeks significantly reduced hepatic adenosine triphosphate (ATP) content; suramin, a purinergic P2 receptor antagonist, abolished the protective effect. Of note, the portal plasma derived from mice fed the inulin-supplemented diet significantly alleviated ConA-induced immune-mediated liver injury. Mechanistically, increased portal short-chain fatty acid (SCFA) levels, such as those of acetate and butyrate, by inulin supplementation leads to up-regulation of hepatic γ-type peroxisome proliferator-activated receptor (Pparg) and uncoupling protein 2 (Ucp2), which uncouples mitochondrial ATP synthesis downstream of PPARγ. Pparg down-regulating small interfering RNA cancelled the protective effect of inulin supplementation against MPO-producing neutrophil infiltration and the subsequent immune-mediated liver injury, suggesting that the SCFA–PPARγ–UCP2 axis plays a key role in the protective effect by inulin supplementation. Moreover, significant changes in the gut microbiota, including increased operational taxonomic units in genera Akkermansia and Allobaculum, also characterized the protective effect of the inulin-supplemented diet. Conclusion: There is a possible unraveled etiopathophysiological link between the maintenance of liver tolerance and dietary fiber. The SCFA–PPARγ–UCP2 axis may provide therapeutic targets for immune-mediated liver injury in the future.

Background Acute decompensation (AD) of liver cirrhosis (LC) and subsequent acute-on-chronic liver failure (ACLF) are fatal and impair quality of life. Insufficient knowledge of the highly heterogeneous natural history of LC, including decompensation, re-compensation, and possible recurrent decompensation, hinders the development and application of novel therapeutics. Approximately 10%-50% of AD/ACLF is reported to be precipitated by any indeterminate (unidentifiable, cryptogenic, or unknown) acute insults; however, its clinical characteristics are unclear. Methods We conducted a single-center observational study of 2165 consecutively admitted patients with LC from January 2012 to December 2019. A total of 466 episodes of AD/ACLF in 285 patients, including their 285 first indexed AD/ACLF, were extracted for analysis. Stratified analyses of different acute precipitants, classified as indeterminate (AD/ACLFIND), bacterial infection (AD/ACLFBAC), gastrointestinal bleeding, active alcoholism, and miscellaneous, were performed. Results AD/ACLFIND was the leading acute precipitant (28%), followed by AD/ACLFBAC (23%). AD/ ACLFIND showed better survival outcomes than AD/ACLFBAC (P = 0.03); however, hyperbilirubinemia, hyponatremia, or leukocytosis significantly and uniquely characterized subgroups of AD/ACLFIND with comparable or even worse survival outcomes than those of AD/ ACLFBAC. Patients with subsequent AD/ACLF significantly tended to suffer from AD/ACLF with any organ failure in AD/ACLFIND but not in AD/ACLFBAC (P = 0.004, for trend). In competing risk analysis, patients with AD/ACLFIND were significantly more vulnerable to suffer from recurrent episodes of AD/ACLF within 180 days, compared to those triggered by other precipitants (P = 0.04). Conclusions AD/ACLFIND, the leading acute precipitant, also plays a role in subsequent AD/ACLF. An abruptly exacerbating, remitting, and relapsing nature of systemic inflammation underlying AD/ACLF may also be useful for risk estimation.

Primary sclerosing cholangitis (PSC) is characterized by progressive biliary inflammation and fibrosis. Although gut commensals are associated with PSC, their causative roles and therapeutic strategies remain elusive. Here we detect abundant Klebsiella pneumoniae (Kp) and Enterococcus gallinarum in fecal samples from 45 PSC patients, regardless of intestinal complications. Carriers of both pathogens exhibit high disease activity and poor clinical outcomes. Colonization of PSC-derived Kp in specific pathogen-free (SPF) hepatobiliary injury-prone mice enhances hepatic Th17 cell responses and exacerbates liver injury through bacterial translocation to mesenteric lymph nodes. We developed a lytic phage cocktail that targets PSC-derived Kp with a sustained suppressive effect in vitro. Oral administration of the phage cocktail lowers Kp levels in Kp-colonized germ-free mice and SPF mice, without off-target dysbiosis. Furthermore, we demonstrate that oral and intravenous phage administration successfully suppresses Kp levels and attenuates liver inflammation and disease severity in hepatobiliary injury-prone SPF mice. These results collectively suggest that using a lytic phage cocktail shows promise for targeting Kp in PSC.

Perivascular epithelioid cell tumors (PEComas) belong to a family of rare mesenchymal tumors composed of histologically and immunohistochemically distinctive perivascular epithelioid cells. Li–Fraumeni syndrome (LFS), an autosomal dominant cancer predisposition syndrome, is caused by a germline variant of the tumor suppressor gene TP53. Here, we report the case of a 20-year-old woman with LFS who developed a PEComa of the liver. She was suspected to have LFS because she had developed osteosarcoma (OS) of the femur along with a concurrent transitional liver cell tumor in the right liver lobe at the age of 8 years. She also tested positive for the germline TP53 missense variant c.722 C > T (p.Ser241Phe). She concurrently experienced recurrence of OS and a new-onset liver tumor at the age of 20 years. Thereafter, microwave ablation was performed for the liver tumor because the Magnetic resonance imaging features suggested that the tumor was a hepatocellular carcinoma. Post-ablation biopsy showed that the tumor cells were spindle-shaped and possessed eosinophilic cytoplasm. Immunohistochemistry revealed that the tumor cells expressed HMB45 and focal alpha-smooth muscle actin. Labeling for S100 protein and cytokeratin-AE1/AE3 yielded negative results. Therefore, a diagnosis of PEComa of the liver was made. Among the ten PEComas reported in patients with Li-Fraumeni syndrome so far, all PEComas except the current case were surgically resected, and no cases of recurrence were documented in the follow-up period. Six of the ten PEComas were located in the liver. We think that the possibility of PEComa should be considered when a liver tumor develops in patients with LFS.

Background: The clinical significance of treatment beyond progression (TBP) with immune checkpoint inhibitor-based therapy in hepatocellular carcinoma (HCC) remains unclear. As atezolizumab plus bevacizumab has become a first-line therapy for advanced HCC, understanding the real-world outcomes of TBP is increasingly relevant. Methods: We conducted a multicenter retrospective observational study involving 122 patients with unresectable HCC treated with atezolizumab plus bevacizumab across nine liver centers in Japan. Among patients who experienced radiologic progressive disease (PD), clinical outcomes were compared between those who continued treatment beyond progression (TBP group) and those who discontinued therapy. Overall survival (OS), tumor response, and subgroup analyses based on major vessel involvement (MVI) were evaluated. Results: Among patients with PD, the median OS was not reached in the TBP group, compared to 13.6 months in the non-TBP group (HR 2.04; 95% CI 1.02–4.07; p=0.0435). When stratified by MVI status, patients without MVI who received TBP had significantly longer OS (median not reached) than those who received palliative care (median 6.2 months; HR 11.2; 95% CI 3.89–32.5; p<0.001). Among patients with MVI, TBP did not confer an OS benefit over palliative care (median OS: 10.4 months vs. 7.4 months; HR 2.24; p=0.260), whereas switching to subsequent chemotherapy showed improved OS (median 23.1 months vs. 7.4 months; HR 7.33; 95% CI 1.44–37.3; p=0.0164). Multivariate analysis identified MVI as an independent negative prognostic factor (HR 5.17; 95% CI 1.34–20.0; p=0.0172), even after adjusting for AFP ratio at progression. Conclusions: This multicenter study suggests that continuation of atezolizumab plus bevacizumab beyond radiologic progression may improve survival outcomes in selected patients with unresectable HCC, particularly those without major vessel involvement. These findings support the integration of TBP into personalized treatment strategies in advanced HCC.

Background: Patients with severe alcohol-associated hepatitis (SAH) have a high short-term mortality rate. Unmet needs exist in patients who are refractory to corticosteroids (CS) or are ineligible for early liver transplantation. Methods: This was a prospective, open-label, nonrandomized pilot study conducted at a liver transplant center in Tokyo, Japan, starting in October 2015. Lille model and Model for End-stage Liver Disease (MELD) score-defined CS nonresponsive or CS-intolerant patients with SAH who fulfilled the inclusion criteria (leukocytosis over 10,000/μL, etc.) were considered for enrollment. The median duration from admission to enrollment was 23 days (IQR, 14-31 days), after standard of care. Granulocyte-monocyte/macrophage apheresis (GMA) performed with Adacolumn twice per week, up to 10 times per treatment course, was evaluated. Results: 13 GMA treatments were conducted through December 2021. Maddrey Discriminant Function was 53.2±17.7 at admission. The overall survival rate was 90.9% at 90 and 180 days. MELD scores significantly improved, from median (IQRs) of 23 (20–25) to 15 (13–21) after GMA (p < 0.0001). Estimated mortality risks using the Lille model and MELD scores significantly improved from 20.9% ± 16.5% to 7.4% ± 7.3% at 2 months and from 30.4% ± 21.3% to 11.6% ± 10.8% at 6 months, respectively (both p < 0.01), and were internally validated. The cumulative rate of alcohol relapse was 35.9% per year. No severe adverse events were observed. In exploratory analysis, granulocyte colony-stimulating factor levels were significantly correlated with prognostic systems such as MELD-Sodium scores after GMA (correlation coefficient = −0.9943, p < 0.0001) but not before GMA (p = 0.62). Conclusions: Compared to published studies, GMA is associated with a lower-than-expected 90- and 180-day mortality in patients with CS-nonresponsive or CS-intolerant SAH. GMA may meet the needs as a salvage anti-inflammatory therapy for SAH. (Trial registration: UMIN000019351 and jRCTs No.032180221) (274 words).

Background & Aims: B-cell depletion therapy with an anti-CD20 is an effective treatment strategy for patients with refractory autoimmune hepatitis (AIH). However, the mechanisms underlying B-cell action are unclear. Methods: Herein, we used the adeno-associated virus IL-12 model, in which hepatic IL-12 expression triggers liver injuries characteristic of AIH. We also analysed the clinical samples of patients with AIH. Results: B-cell depletion using anti-CD20 or splenectomy was found to improve liver functions and decrease the cytotoxic CD8+ T-cell (cytotoxic T lymphocyte [CTL]) count in the liver. This improvement was reversed by the adoptive transfer of splenic B cells derived from AAV IL-12-treated mice to splenectomised mice as it caused the hepatic CTL count to increase. RNA-sequencing analysis identified IL-15 as a key factor in pathogenic B cells, which promotes CTL expansion and subsequent migration to the liver via the CXCL9/CXCR3 axis. Indeed, IL-15 neutralisation ameliorated hepatitis by suppressing splenic and hepatic CTLs in vivo. The close distribution of B220+ B cells and CD8+ T cells in the spleen of AIH mice suggested mutual interactions. Mechanistically, IFNγ and CD40L/CD40 signalling were indispensable for the expression of IL-15 in B cells, and in vitro co-culture experiments revealed that splenic CD40L+CD8+ T cells promoted IL-15 production in B cells, which led to CTL expansion. In patients with AIH, high serum IL-15 concentration and IL-15+ B-cell counts, positively correlating with serum alanine aminotransferase levels, support translation and potential therapeutic targeting in human AIH. Conclusions: This investigation elucidated the roles of IL-15-producing splenic B cells that occur in concert with pathogenic CD8+ T cells during the development of AIH. Impact and Implications: IL-15-producing B cells were shown to exacerbate experimental AIH via cytotoxic T lymphocyte expansion. CD40L+CD8+ T cells promoted IL-15 expression in B cells, indicating the mutual interaction of both cells. High serum IL-15 concentrations, IL-15+ B-cell counts, and CD40L+IL-15Rα+CD8+ T-cell counts were confirmed in the blood of patients with AIH.

Development of subclassification of intermediate-stage hepatocellular carcinoma (HCC) by treatment suitability is in demand. We aimed to identify predictors that define treatment refractoriness against locoregional(transarterial chemoembolization(TACE) or thermal ablation) and surgical therapy. This multicenter retrospective study enrolled 1167 HCC patients between 2015 and 2021. Of those, 209 patients were initially diagnosed with intermediate-stage HCC. Treatment refractoriness was defined as clinical settings that meets the following untreatable progressive conditions by TACE (1) 25% increase of intrahepatic tumor, (2) transient deterioration to Child–Pugh class C, (3) macrovascular invasion or extrahepatic spread, within one year. We then analyzed factors contributing to treatment refractoriness. The Child–Pugh score/class, number of tumors, infiltrative radiological type, and recurrence were significant factors. Focusing on recurrence as a predictor, median time to untreatable progression (TTUP) was 17.2 months in the recurrence subgroup whereas 35.5 months in the initial occurrence subgroup (HR, 2.06; 95% CI, 1.44–2.96; P = 0.001). Median TTUP decreased in cases with more later times of recurrence (3–5 recurrences, 17.3 months; ≥ 6 recurrences, 7.7 months). Recurrence, even more at later times, leads to increased treatment refractoriness. Early introduction of multidisciplinary treatment should be considered against HCC patients after multiple recurrent episodes.

The fate of resolution of liver fibrosis after withdrawal of liver injury is still incompletely elucidated. Toll-like receptor 4 (TLR4) in tissue fibroblasts is pro-fibrogenic. After withdrawal of liver injury, we unexpectedly observed a significant delay of fibrosis resolution as TLR4 signaling was pharmacologically inhibited in vivo in two murine models. Single-cell transcriptome analysis of hepatic CD11b+ cells, main producers of matrix metalloproteinases (MMPs), revealed a prominent cluster of restorative Tlr4-expressing Ly6c2-low myeloid cells. Delayed resolution after gut sterilization suggested its microbiome-dependent nature. Enrichment of a metabolic pathway linking to a significant increase of bile salt hydrolase-possessing family Erysipelotrichaceae during resolution. Farnesoid X receptor-stimulating secondary bile acids including 7-oxo-lithocholic acids upregulated MMP12 and TLR4 in myeloid cells in vitro. Fecal material transplant in germ-free mice confirmed phenotypical correlations in vivo. These findings highlight a pro-fibrolytic role of myeloid TLR4 signaling after injury withdrawal and may provide targets for anti-fibrotic therapy.

Recent advances in the analysis of intestinal bacteria have led to reports of variations in intestinal bacterial levels among hepatobiliary diseases. The mechanisms behind the changes in intestinal bacteria in various hepatobiliary diseases include the abnormal composition of intestinal bacteria, weakening of the intestinal barrier, and bacterial translocation outside the intestinal tract, along with their metabolites, but many aspects remain unresolved. Further research employing clinical studies and animal models is expected to clarify the direct relationship between intestinal bacteria and hepatobiliary diseases and to validate the utility of intestinal bacteria as a diagnostic biomarker and potential therapeutic target. This review summarizes the involvement of the microbiota in the pathogenesis of hepatobiliary diseases via the gut-liver axis.

The liver presents a unique immune system. Liver diseases are closely associated with the immune system. Disruption of the tightly regulated balance between immune activation and tolerance induction leads to the development and worsening of immune-related liver diseases. T cells play diverse crucial roles in the immune system, and they have long been known to induce inflammation through direct tissue damage by effector molecules and the recruitment of effector cells via chemokines. Additionally, T cells interact with B cells to induce autoantibodies, promoting tissue inflammation and dysfunction through the deposition of IgG and immune complexes in the tissues. Recent advances in omics technologies, including single-cell RNA sequencing and spatial transcriptomics, have elucidated the role of T cells in the progression and recovery of liver fibrosis. Moreover, comprehensive and unbiased information can now be obtained from small samples of human and mouse tissues, which advances our understanding of tissue-specific functions of T cells, including resident memory T cells, peripheral helper T cells, and tissue Tregs. However, significant unmet needs remain in the fields of immune-related liver diseases. In this review, we discuss the T cell biology and its role in autoimmune hepatitis (AIH), primary sclerosing cholangitis (PSC), primary biliary cholangitis (PBC), and metabolic-associated steatohepatitis (MASH), which are non-viral liver diseases exhibiting a strong involvement of immunity and inflammation. Furthermore, the latest therapeutic concepts for the diseases and associated drugs targeting T cells have been overviewed.

Background and Aim: Liver transplantation is the only curative treatment for end-stage liver disease; however, access remains limited, particularly in Japan, where the severe shortage of deceased donors presents a major challenge. Research comprehensively assessing the full trajectory from referral to either transplantation or death remains scarce. We aimed to analyze long-term trends and propose potential strategies to improve access to liver transplantation in Japan. Patients and Methods: This study included 616 adult patients with decompensated liver cirrhosis referred for liver transplantation. Patients were divided into 3 periods to assess temporal trends: Period 1 (2009-2013), Period 2 (2014-2018), and Period 3 (2019-2023). The primary endpoint was the liver transplantation rate among referred patients. Patient demographics, liver disease etiology and severity, and donor type were analyzed. Results: The transplantation rate declined from 30.2% in Period 1 to 22.1% in Period 3, despite increases in follow-up rates and waitlist registrations. The availability of living donors significantly decreased over time, from 29.5% in Period 1 to 22.4% in Period 2 and 18.6% in Period 3. The rate of death without transplantation remained high (41.0%, 45.0%, and 40.0%, respectively). A higher MELD score at referral was an independent risk factor for both not undergoing transplantation and mortality among transplantation candidates. Conclusion: Over this 15-year period, the transplantation rate declined despite increases deceased donor registrations, resulting in persistently high waitlist mortality. Our findings suggest that expanding deceased donor pool and facilitating earlier referral of transplant candidates are essential to improving access to transplantation and patient outcomes in a Japanese transplant setting.