The Role of B Cells and B Cell Therapies in Immune-Mediated Liver Diseases

Systemic lupus erythematosus and autoimmune hepatitis overlap disease in a hospitalized systemic lupus erythematosus cohort

Liver dysfunction in systemic lupus erythematosus (SLE) is caused by disease activity or secondary conditions like coexistent autoimmune liver diseases. In Taiwan, despite sporadically reported cases of SLE-autoimmune hepatitis (AIH) overlap disease, larger-scale monocentric investigations for such overlapping patients are not available. Retrospective analyses were performed in a hospitalized SLE cohort with 805 patients for identifying co-existent AIH from 2014 to 2023, focusing on distinct therapeutic modalities and differential diagnosis between SLE-AIH overlap and lupus hepatitis (LH). There were 5 cases (a 0.6% occurrence), all females aged 25-58 years (44 ± 13). Ages for the SLE diagnosis were 19-51 years (30 ± 13), while ages for the AIH diagnosis were 22-57 years (36 ± 14). Contradictory to interface hepatitis in SLE-AIH overlap, liver biopsy only demonstrated non-specific abnormalities in LH. Liver cirrhosis was identified in SLE-AIH overlap but not in LH. After corticosteroids/azathioprine therapy, there were normalized liver function in all LH. In 2 SLE-AIH overlap cases refractory to such therapy, one received B-cell depletion therapy (annual rituximab infusion, 375 mg/m2 weekly × 4) and another accepted living-donor liver transplantation from sibling due to advanced liver cirrhosis, leading to improved hepatic dysfunction in both.

Repurposing of rituximab biosimilars to treat B cell mediated autoimmune diseases

Rituximab, the first monoclonal antibody approved for the treatment of lymphoma, eventually became one of the most popular and versatile drugs ever in terms of clinical application and revenue. Since its patent expiration, and consequently, the loss of exclusivity of the original biologic, its repurposing as an off-label drug has increased dramatically, propelled by the development and commercialization of its many biosimilars. Currently, rituximab is prescribed worldwide to treat a vast range of autoimmune diseases mediated by B cells. Here, we present a comprehensive overview of rituximab repurposing in 115 autoimmune diseases across 17 medical specialties, sourced from over 1530 publications. Our work highlights the extent of its off-label use and clinical benefits, underlining the success of rituximab repurposing for both common and orphan immune-related diseases. We discuss the scientific mechanism associated with its clinical efficacy and provide additional indications for which rituximab could be investigated. Our study presents rituximab as a flagship example of drug repurposing owing to its central role in targeting cluster of differentiate 20 positive (CD20) B cells in 115 autoimmune diseases.

B cell immune profiles in dysbiotic vermiform appendixes of pancreatic cancer patients

Pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest solid tumors and is resistant to immunotherapy. B cells play an essential role in PDAC progression and immune responses, both locally and systemically. Moreover, increasing evidence suggests that microbial compositions inside the tumor, as well as in the oral cavity and the gut, are important factors in shaping the PDAC immune landscape. However, the gut-associated lymphoid tissue (GALT) has not previously been explored in PDAC patients. In this study, we analyzed healthy vermiform appendix (VA) from 20 patients with PDAC and 32 patients with colon diseases by gene expression immune profiling, flow cytometry analysis, and microbiome sequencing. We show that the VA GALT of PDAC patients exhibits markers of increased inflammation and cytotoxic cell activity. In contrast, B cell function is decreased in PDAC VA GALT based on gene expression profiling; B cells express significantly fewer MHC class II surface receptors, whereas plasma cells express the immune checkpoint molecule HLA-G. Additionally, the vermiform appendix microbiome of PDAC patients is enriched with Klebsiella pneumoniae, Bifidobacterium animalis, and Adlercreutzia equolifaciens, while certain commensals are depleted. Our findings may suggest impaired B cell function within the GALT of PDAC patients, which could potentially be linked to microbial dysbiosis. Additional investigations are imperative to validate our observations and explore these potential targets of future therapies.

Rituximab in Pemphigus Vulgaris: A Review of Monoclonal Antibody Therapy in Dermatology

Pemphigus vulgaris (PV) is a rare autoimmune blistering disorder that primarily affects the skin and mucous membranes. Conventional treatments for PV, such as corticosteroids and immunosuppressive agents, have limitations in terms of efficacy and long-term safety. Monoclonal antibody therapy, specifically rituximab, has emerged as a promising therapeutic approach in the management of PV. This review article provides a comprehensive overview of rituximab in the treatment of PV, with a focus on its efficacy, safety profile, and immunological mechanisms of action. The article begins with an introduction to PV and the significance of monoclonal antibody therapy in dermatology. It then explores the clinical presentation and underlying immune-mediated mechanisms of PV, highlighting the autoimmune nature of the disease. The rationale for using monoclonal antibody therapy, particularly rituximab, in PV is discussed, emphasizing the limitations of conventional treatments and the concept of targeted therapy. The review delves into the efficacy and safety of rituximab based on clinical studies, evaluating disease remission rates, duration, and relapse rates. Furthermore, the immunological effects of rituximab, including B-cell depletion and modulation of the immune response, are explored in detail. Comparisons between rituximab and conventional treatment modalities in PV are made, assessing clinical outcomes, safety profiles, and long-term efficacy. Challenges and considerations in rituximab therapy are discussed, including factors influencing its efficacy, optimal dosing, treatment duration, and the need for maintenance therapy.

Recent progress on the treatment of type 1 autoimmune pancreatitis and IgG4-related disease

IgG4-related disease (IgG4-RD) is a fibroinflammatory disorder recognized as a novel clinical entity with either synchronous or metachronous multiorgan involvement. Autoimmune pancreatitis (AIP) is classified into two types: type 1 AIP as a pancreatic manifestation of IgG4-RD and type 2 AIP with granulocytic epithelial lesion and occasional association with ulcerative colitis. Although the pathogenic mechanism still remains unclear, possible multipathogenic factors such as genetic factors, disease-specific or related antigens, and abnormal innate or adaptive immunity may be involved in the development of IgG4-RD. Many immunocytes including M2 macrophages, plasmablasts, B cells, and T-cells (Th2-CD4+T, follicular helper T-cells, and CD4+SLAMF7+cytotoxic T-cells) play important roles in the pathogenesis. Conventional induction and maintenance therapies with glucocorticoid or rituximab are recommended in all symptomatic patients with active IgG4-RD. In those at risk for irreversible damage in any organs, this should be done urgently, regardless of symptoms. As no randomized clinical trials other than glucocorticoid maintenance therapy for type 1 AIP have been performed, the comprehensive management for IgG4-RD has not been established yet. Targeted treatment approaches against the plasmablast to B cell lineage and the CD4+ SLAMF7+ cytotoxic T-cell seem to be promising for the future-directed treatment.

Role of B Cell-Activating Factor in Fibrosis Progression in a Murine Model of Non-Alcoholic Steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease all over the world. Therapeutic strategies targeting its multidirectional pathways are required. Particularly, fibrosis is closely associated with its prognosis. We previously found that B cell-activating factor (BAFF) is associated with severity of NAFLD. Here, we determined the direct in vivo role of BAFF in the development of liver fibrosis. Histological and biochemical analyses were performed using wild-type and BAFF-deficient mice. We established a murine model of non-alcoholic steatohepatitis (NASH) using carbon tetrachloride injection accompanied by high-fat/high-cholesterol diet feeding. Additionally, in vitro analysis using mouse macrophage-like cell line RAW264.7 and primary hepatic stellate cells was performed. Hepatic steatosis and inflammation, and most importantly, the progression of liver fibrosis, were ameliorated in BAFF-deficient mice compared to those wild-type mice in our model. Additionally, BAFF deficiency reduced the number of CD11c⁺ M1-type macrophages in the liver. Moreover, BAFF stimulated RAW264.7 cells to secrete nitric oxide and tumor necrosis factor α, which drove the activation of hepatic stellate cells. This indicates that BAFF plays a crucial role in NASH development and may be a promising therapeutic target for NASH.

Ongoing involvers and promising therapeutic targets of hepatic fibrosis: The hepatic immune microenvironment

Hepatic fibrosis is often secondary to chronic inflammatory liver injury. During the development of hepatic fibrosis, the damaged hepatocytes and activated hepatic stellate cells (HSCs) caused by the pathogenic injury could secrete a variety of cytokines and chemokines, which will chemotactic innate and adaptive immune cells of liver tissue and peripheral circulation infiltrating into the injury site, mediating the immune response against injury and promoting tissue reparation. However, the continuous release of persistent injurious stimulus-induced inflammatory cytokines will promote HSCs-mediated fibrous tissue hyperproliferation and excessive repair, which will cause hepatic fibrosis development and progression to cirrhosis even liver cancer. And the activated HSCs can secrete various cytokines and chemokines, which directly interact with immune cells and actively participate in liver disease progression. Therefore, analyzing the changes in local immune homeostasis caused by immune response under different pathological states will greatly enrich our understanding of liver diseases' reversal, chronicity, progression, and even deterioration of liver cancer. In this review, we summarized the critical components of the hepatic immune microenvironment (HIME), different sub-type immune cells, and their released cytokines, according to their effect on the development of progression of hepatic fibrosis. And we also reviewed and analyzed the specific changes and the related mechanisms of the immune microenvironment in different chronic liver diseases.Moreover, we retrospectively analyzed whether the progression of hepatic fibrosis could be alleviated by modulating the HIME.We aimed to elucidate the pathogenesis of hepatic fibrosis and provide the possibility for exploring the therapeutic targets for hepatic fibrosis.

Immunobiology of the biliary tract system

The biliary tract is a complex tubular organ system spanning from the liver to the duodenum. It is the site of numerous acute and chronic disorders, many of unknown origin, that are often associated with cancer development and for which there are limited treatment options. Cholangiocytes with proinflammatory capacities line the lumen and specialised types of immune cells reside in close proximity. Recent technological breakthroughs now permit spatiotemporal assessments of immune cells within distinct niches and have increased our understanding of immune cell tissue residency. In this review, a comprehensive overview of emerging knowledge on the immunobiology of the biliary tract system is provided, with a particular emphasis on the role of distinct immune cells in biliary disorders.

The immunological function of CXCR2 in the liver during sepsis

Background

The chemokine receptor CXCR2 and its ligands, especially CXCL8, are crucial mediators for the progression of liver inflammation and liver failure in sepsis. Neutrophils have the highest CXCR2 expression in mice and humans, and their activation via CXCL8 facilitates their migration to the inflamed liver for the clearance of the pathogens and, in turn, the inflammation.

Main body

In sepsis, the inflammatory insult causes extensive neutrophil migration to the liver that overwhelms the immune response. To compensate for the strong receptor activation, CXCR2 desensitizes, incapacitating the immune cells to efficiently clear pathogens, causing further life-threatening liver damage and uncontrolled pathogen spread.

Conclusion

CXCR2 function during infection strongly depends on the expressing cell type. It signals pro- and anti-inflammatory effects that may prompt novel cell-type-specific CXCR2-directed therapeutics.

The liver-resident immune cell repertoire - A boon or a bane during machine perfusion?

The liver has been proposed as an important “immune organ” of the body, as it is critically involved in a variety of specific and unique immune tasks. It contains a huge resident immune cell repertoire, which determines the balance between tolerance and inflammation in the hepatic microenvironment. Liver-resident immune cells, populating the sinusoids and the space of Disse, include professional antigen-presenting cells, myeloid cells, as well as innate and adaptive lymphoid cell populations. Machine perfusion (MP) has emerged as an innovative technology to preserve organs ex vivo while testing for organ quality and function prior to transplantation. As for the liver, hypothermic and normothermic MP techniques have successfully been implemented in clinically routine, especially for the use of marginal donor livers. Although there is evidence that ischemia reperfusion injury-associated inflammation is reduced in machine-perfused livers, little is known whether MP impacts the quantity, activation state and function of the hepatic immune-cell repertoire, and how this affects the inflammatory milieu during MP. At this point, it remains even speculative if liver-resident immune cells primarily exert a pro-inflammatory and hence destructive effect on machine-perfused organs, or in part may be essential to induce liver regeneration and counteract liver damage. This review discusses the role of hepatic immune cell subtypes during inflammatory conditions and ischemia reperfusion injury in the context of liver transplantation. We further highlight the possible impact of MP on the modification of the immune cell repertoire and its potential for future applications and immune modulation of the liver.

Challenges and opportunities in achieving effective regulatory T cell therapy in autoimmune liver disease

Autoimmune liver diseases (AILD) include autoimmune hepatitis (AIH), primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC). These immune-mediated liver diseases involve a break down in peripheral self-tolerance with largely unknown aetiology. Regulatory T cells (Treg) are crucial in maintaining immunological tolerance. Hence, Treg immunotherapy is an attractive therapeutic option in AILD. Currently, AILD do not have a curative treatment option and patients take life-long immunosuppression or bile acids to control hepatic or biliary inflammation. Clinical investigations using good manufacturing practice (GMP) Treg in autoimmune liver disease have thus far demonstrated that Treg therapy is safe and that Treg migrate to inflamed liver tissue. For Treg immunotherapy to achieve efficacy in AILD, Treg must be retained within the liver and maintain their suppressive phenotype to dampen ongoing immune responses to hepatocytes and biliary epithelium. Therefore, therapeutic Treg subsets should be selected for tissue residency markers and maximal functionality. Optimisation of dosing regime and understanding longevity of Treg in vivo are critical to successful Treg therapy. It is also essential to consider combination therapy options to complement infused Treg, for instance low-dose interleukin-2 (IL-2) to support pre-existing and infused Treg survival and suppressive function. Understanding the hepatic microenvironment in both early- and late-stage AILD presents significant opportunity to better tailor Treg therapy in different patient groups. Modification of a hostile microenvironment to a more favourable one either prior to or during Treg therapy could enhance the efficacy and longevity of infused GMP-Treg. Applying recent technology to discovery of autoantigen responses in AILD, T cell receptor (TCR) sequencing and use of chimeric antigen receptor (CAR) technology represents the next frontier for disease-specific CAR-Treg therapies. Consideration of all these aspects in future trials and discovery research would position GMP Treg immunotherapy as a viable personalised-medicine treatment option for effective control of autoimmune liver diseases.

WITHDRAWN: The Role of the Vascular Niche in Organ Fibrosis and COVID-19-Related Organ Damage and the Countermeasures adopted by Chinese and Western Medicine

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Inhibition of Bruton Tyrosine Kinase Reduces Neuroimmune Cascade and Promotes Recovery after Spinal Cord Injury

Microglia/astrocyte and B cell neuroimmune responses are major contributors to the neurological deficits after traumatic spinal cord injury (SCI). Bruton tyrosine kinase (BTK) activation mechanistically links these neuroimmune mechanisms. Our objective is to use Ibrutinib, an FDA-approved BTK inhibitor, to inhibit the neuroimmune cascade thereby improving locomotor recovery after SCI. Rat models of contusive SCI, Western blot, immunofluorescence staining imaging, flow cytometry analysis, histological staining, and behavioral assessment were used to evaluate BTK activity, neuroimmune cascades, and functional outcomes. Both BTK expression and phosphorylation were increased at the lesion site at 2, 7, 14, and 28 days after SCI. Ibrutinib treatment (6 mg/kg/day, IP, starting 3 h post-injury for 7 or 14 days) reduced BTK activation and total BTK levels, attenuated the injury-induced elevations in Iba1, GFAP, CD138, and IgG at 7 or 14 days post-injury without reduction in CD45RA B cells, improved locomotor function (BBB scores), and resulted in a significant reduction in lesion volume and significant improvement in tissue-sparing 11 weeks post-injury. These results indicate that Ibrutinib exhibits neuroprotective effects by blocking excessive neuroimmune responses through BTK-mediated microglia/astroglial activation and B cell/antibody response in rat models of SCI. These data identify BTK as a potential therapeutic target for SCI.

The Role of B Cells in Adult and Paediatric Liver Injury

B lymphocytes are multitasking cells that direct the immune response by producing pro- or anti-inflammatory cytokines, by presenting processed antigen for T cell activation and co-stimulation, and by turning into antibody-secreting cells. These functions are important to control infection in the liver but can also exacerbate tissue damage and fibrosis as part of persistent inflammation that can lead to end stage disease requiring a transplant. In transplantation, immunosuppression increases the incidence of lymphoma and often this is of B cell origin. In this review we bring together information on liver B cell biology from different liver diseases, including alcohol-related and metabolic fatty liver disease, autoimmune hepatitis, primary biliary and primary sclerosing cholangitis, viral hepatitis and, in infants, biliary atresia. We also discuss the impact of B cell depletion therapy in the liver setting. Taken together, our analysis shows that B cells are important in the pathogenesis of liver diseases and that further research is necessary to fully characterise the human liver B cell compartment.

Immunosuppressive drugs modes of action

The innate and adaptive immune systems work as a complex interplay between different cell types, involving cytokines and chemokines mediating extracellular and paracrine effects. At the intracellular level, the inflammatory cascade is mediated by multifaceted processes that have been better described in the last 10 years. Immunosuppressive agents available in clinical practice act at different points of those cascades at the intracellular or extracellular level. Those drugs can mediate their effects on one or more cell types finally limiting inflammation and immune responses to antigens. Every immunosuppressive agent is characterized by intrinsic toxicity and side effects that may be due to the same therapeutic pathways or to off-target secondary effect of each molecule. We will here review the mechanisms of action of the most widely used immunosuppressive agents in the field of solid organ transplantation and autoimmune disorders, describing the mechanisms underlying both the therapeutic and secondary effects.