The advantage of Sirolimus in amplifying regulatory B cells and regulatory T cells in liver transplant patients

Clinical features and risk factors for Sjogren's syndrome patients suffering from oral candidiasis in Shanxi, China

OBJECTIVES

To investigate the clinical features and risk factors of Sjogren's Syndrome (SS) patients suffering from oral candidiasis and to provide a foundation for the prevention and treatment of oral candidiasis in SS patients.

METHODS

The medical records of 479 SS patients admitted to the Second Hospital of Shanxi Medical University from 2018 to 2020 were analysed to determine the clinical characteristics and risk factors that influence the occurrence of oral candidiasis infection in SS patients.

RESULTS

Patients with oral candidiasis were older than those without oral candidiasis (P < 0.05). Male SS patients had greater oral candidiasis rates (P < 0.05). Unstimulated whole saliva (UWS) and stimulated whole saliva (SWS) were both shown to be adversely associated with oral Candida infections (P < 0.001). Logistic regression revealed that a low UWS was an independent risk factor for oral Candida infections in SS patients (OR: 0.004, P = 0.023). Greater WBC counts (OR: 1.22, P < 0.001), lower haemoglobin levels (OR: 0.97, P = 0.007), lower serum albumin levels (OR: 0.88, P < 0.001), lower IgG levels (OR: 0.91, P = 0.011), lower IgA levels (OR: 0.75, P = 0.011), and lower IgM levels (OR: 0.91, P = 0.015) were found in patients with oral Candida infections. Patients on immunosuppressive medications (OR: 0.32, P = 0.011), particularly rapamycin (P < 0.001), had a decreased rate of oral Candida infections.

CONCLUSIONS

Patients with oral candidiasis were older than those without oral candidiasis. Male SS patients are more likely to have oral candidiasis. Individuals with lower UWS and SWS are more susceptible to oral Candida infection. Oral Candida infections in SS patients depend on their immunological status. Rapamycin may increase the abundance of Treg cells to reduce oral Candida infection in SS patients.

B Cell-mediated Immune Regulation and the Quest for Transplantation Tolerance

Pathophysiologic function of B cells in graft rejection has been well recognized in transplantation. B cells promote alloantigen-specific T-cell response and secrete antibodies that can cause antibody-mediated graft failures and rejections. Therefore, strategies targeting B cells, for example, B-cell depletion, have been used for the prevention of both acute and chronic rejections. Interestingly, however, recent mounting evidence indicates that subsets of B cells yet to be further identified can display potent immune regulatory functions, and they contribute to transplantation tolerance and operational tolerance in both experimental and clinical settings, respectively. In this review, we integrate currently available information on B-cell subsets, including T-cell Ig domain and mucin domain 1-positive transitional and T-cell immunoreceptor with Ig and immunoreceptor tyrosine-based inhibitory motif domain-positive memory B cells, displaying immune regulatory functions, with a focus on transplantation tolerance, by analyzing their mechanisms of action. In addition, we will discuss potential T-cell Ig domain and mucin domain 1-positive and T-cell immunoreceptor with Ig and immunoreceptor tyrosine-based inhibitory motif domain-positive B cell-based strategies for the enhancement of operational tolerance in transplantation patients.

B cell-T cell interplay in immune regulation: A focus on follicular regulatory T and regulatory B cell functions

B cells are the core components of humoral immunity. A mature B cell can serve in multiple capacities, including antibody production, antigen presentation, and regulatory functions. Forkhead box P3 (FoxP3)-expressing regulatory T cells (Tregs) are key players in sustaining immune tolerance and keeping inflammation in check. Mounting evidence suggests complex communications between B cells and Tregs. In this review, we summarize the yin-yang regulatory relationships between B cells and Tregs mainly from the perspectives of T follicular regulatory (Tfr) cells and regulatory B cells (Bregs). We discuss the regulatory effects of Tfr cells on B cell proliferation and the germinal center response. Additionally, we review the indispensable role of B cells in ensuring homeostatic Treg survival and describe the function of Bregs in promoting Treg responses. Finally, we introduce a new subset of Tregs, termed Treg-of-B cells, which are induced by B cells, lake the expression of FoxP3 but still own immunomodulatory effects. In this article, we also enumerate a sequence of research from clinical patients and experimental models to clarify the role of Tfr cells in germinal centers and the role of convention B cells and Bregs to Tregs in the context of different diseases. This review offers an updated overview of immunoregulatory networks and unveils potential targets for therapeutic interventions against cancer, autoimmune diseases and allograft rejection.

Sirolimus Monotherapy for Thrombocytopenia in Primary Antiphospholipid Syndrome: A Pilot Study From a Tertiary Referral Center

Background

Thrombocytopenia (TP) is considered as a warning sign of high-risk antiphospholipid syndrome (APS) and sometimes a paradoxical sign of anti-thrombosis treatment. Currently, there is an extreme paucity of effective and safe drugs for long-term management of TP in primary APS patients; therefore, we explored the efficacy and safety of sirolimus monotherapy.

Methods

In this real-world study, we included 7 consecutive patients with primary APS who received sirolimus monotherapy for TP. Oral sirolimus was initiated at a dose of 1–2 mg once daily and then adjusted primarily based on clinical efficacy and tolerance, with consideration of the sirolimus trough concentration of ≤15 ng/ml.

Results

Of included patients, the median age was 58 years with a median disease course of 1.5 years and 4 patients were treatment-naïve. All patients completed 6 months of sirolimus therapy with a median follow-up of 6 months (range: 6–15). All patients received sirolimus monotherapy for TP during the entire follow-up, without any additional agents. Overall, the platelet count exhibited a substantially increasing trend after sirolimus administration during the first 6 months (p < 0.001) and stability later. Specifically, the median platelet count was significantly increased from 59 × 10⁹/l before sirolimus to 90 × 10⁹/l at month 1 (p = 0.028), 131 × 10⁹/l at 3 months (p = 0.028), and 178 × 10⁹/l at 6 months (p = 0.018). Overall and complete responses were respectively achieved in 6 (85.7%) and 5 (71.4%) patients at month 6. Importantly, overall response was achieved in all 4 treatment-naïve patients. Additionally, there were different extents of decline in the titers of antiphospholipid antibodies after sirolimus treatment. Regarding safety, only one patient experienced an elevated cholesterol level with recovery after atorvastatin treatment.

Conclusion

Sirolimus monotherapy confers good efficacy and tolerance for TP in primary APS patients and therefore may be considered as a first-line therapy.

Regulatory B Cell Therapy in Kidney Transplantation

In the context of kidney injury, the role of Bregs is gaining interest. In a number of autoimmune diseases, the number and/or the function of Bregs has been shown to be impaired or downregulated, therefore restoring their balance might be a potential therapeutic tool. Moreover, in the context of kidney transplantation their upregulation has been linked to tolerance. However, a specific marker or set of markers that define Bregs as a unique cell subset has not been found and otherwise multiple phenotypes of Bregs have been studied. A quest on the proper markers and induction mechanisms is now the goal of many researchers. Here we summarize the most recent evidence on the role of Bregs in kidney disease by describing the relevance of in vitro and in vivo Bregs induction as well as the potential use of Bregs as cell therapy agents in kidney transplantation.

Transplantation of mesenchymal stem cells ameliorates systemic lupus erythematosus and upregulates B10 cells through TGF-β1

BACKGROUND

Considerable experimental and clinical evidences have proved that human umbilical cord mesenchymal stem cells (UC-MSCs) transplantation was powerful in systemic lupus erythematosus (SLE) treatment. MSCs could upregulate regulatory B cells (Bregs) in the mice model of the other immune disease. However, the regulation of MSCs on Bregs in SLE environment remains unclear.

METHODS

To assess the abilities of UC-MSCs to treat SLE, MSCs were transferred intravenously to 17- to 18-week-old MRL/lpr mice. Four weeks later, mice were sacrificed. Survival rates, anti-dsDNA antibodies and renal histology were evaluated. CD4+ T helper (Th) cell subgroups and interleukin (IL)-10+ Bregs (B10) in the spleen were quantitated by flow cytometry. The changes of transforming growth factor (TGF)-β1, IL-6 and indoleamine 2,3-dioxyenase (IDO) mRNAs expressed by MSCs after co-cultured with B cells were detected using real-time polymerase chain reaction (RT-PCR). MSCs were infected by lentivirus carrying TGF-β1 shRNAs, then MSCs with low expression of TGF-β1 were conducted for co-culture in vitro and transplantation experiments in vivo.

RESULTS

UC-MSCs transplantation could efficiently downregulate 24 h proteinuria and anti-dsDNA antibodies, correct Treg/Th17/Th1 imbalances and increase the frequency of B10 cells. The expression of TGF-β1 in MSCs was significantly increased after co-culture with B cells. Downregulation of TGF-β1 in MSCs could significantly attenuate the upregulation of B10 by MSCs in vitro and in vivo. Downregulation of TGF-β1 also compromised the immunomodulation effects of MSCs on Th17 and Treg cells and the therapeutic effects of MSC transplantation.

CONCLUSIONS

UC-MSCs could protect against SLE in mice and upregulate IL-10+ Bregs via TGF-β1.

TIPE2-modified human amnion-derived mesenchymal stem cells promote the efficacy of allogeneic heart transplantation through inducing immune tolerance

Background

Immune rejection of heart transplantation has been regarded as the biggest challenge encountered by a patient suffering from end-stage heart disease. The transplantation of human amnion-derived mesenchymal stem cells (hAD-MSCs) has exhibited promising application prospects in organ transplantation. However, its persistent unsatisfactory tolerance has limited the widespread application of this technology. We aim to investigate the role of tumor necrosis factor-α-induced protein-8 like-2 (TIPE2)-mediated hAD-MSCs in immune tolerance in heart transplantation and its molecular regulatory mechanisms.

Methods

This project detected the effect of TIPE2 on immune tolerance by constructing an allogeneic heart transplantation mouse model through which TIPE2-overexpressed hAD-MSCs were injected into recipients. The fluorescence distribution of TIPE2-hAD-MSCs in mice was observed by a small animal in vivo imaging system. Pathological changes of the transplanted heart were detected by hematoxylin and eosin (HE) staining. Flow cytometry was performed to detect the content of cardiac lymphocytes. The expression of immune-induced related factors was measured by quantitative real-time PCR (qRT-PCR) and western blot assays.

Results

TIPE2-hAD-MSCs protected myocardial tissue structures, reduced the spleen and thymus indexes in recipient mice, minimized the content of cardiac lymphocytes, reduced expressions of ERK, p38, and IFN-γ, and elevated expressions of both IL-10 and TGF-β, markedly improving the survival time and survival rates of recipient mice.

Conclusions

TIPE2-hAD-MSCs induce immune tolerance and improve the survival rates of allogeneic heart transplantation in mice. This study is expected to offer an ideal source and target of cells for organ transplantation.

Harnessing Mechanisms of Immune Tolerance to Improve Outcomes in Solid Organ Transplantation: A Review

Survival after solid organ transplantation (SOT) is limited by chronic rejection as well as the need for lifelong immunosuppression and its associated toxicities. Several preclinical and clinical studies have tested methods designed to induce transplantation tolerance without lifelong immune suppression. The limited success of these strategies has led to the development of clinical protocols that combine SOT with other approaches, such as allogeneic hematopoietic stem cell transplantation (HSCT). HSCT prior to SOT facilitates engraftment of donor cells that can drive immune tolerance. Recent innovations in graft manipulation strategies and post-HSCT immune therapy provide further advances in promoting tolerance and improving clinical outcomes. In this review, we discuss conventional and unconventional immunological mechanisms underlying the development of immune tolerance in SOT recipients and how they can inform clinical advances. Specifically, we review the most recent mechanistic studies elucidating which immune regulatory cells dampen cytotoxic immune reactivity while fostering a tolerogenic environment. We further discuss how this understanding of regulatory cells can shape graft engineering and other therapeutic strategies to improve long-term outcomes for patients receiving HSCT and SOT.

Effect of Short-Term Tacrolimus Exposure on Rat Liver: An Insight into Serum Antioxidant Status, Liver Lipid Peroxidation, and Inflammation

Tacrolimus (TAC) is an immunosuppressive drug, optimally used for liver, kidney, and heart transplant to avoid immune rejection. In retrospect, a multitude of studies have reported effects of TAC, such as nephrotoxicity, diabetes, and other complications. However, limited information is available regarding short-term exposure of TAC on the liver. Therefore, the present study was designed to unravel the effects of short-term exposure of TAC on a rat model. The animal model was established by TAC administration for 6, 12, 24, and 48 h time points. Liver histopathological changes were observed with PAS-D, reticulin stain, and immunostaining of PCNA and CK-7 coupled with glycogen quantification in a liver homogenate. TUNEL assay was performed to evaluate the DNA damage in the liver. Concentration of GSH and activities of SOD and CAT in the serum were measured to assess the antioxidant status, whereas liver tissue MDA level was measured as a biomarker of oxidative stress. Hepatic gene expression analysis of IL-10, IL-13, SOCS-2, and SOCS-3 was performed by RT-PCR. Results revealed marked changes in liver architecture of all TAC-treated groups, as evidenced by sinusoid dilation, hepatocyte derangement, glycogen deposition, and collapsed reticulin fibers. Significant increase in PCNA and CK-7 immunostaining along with the presence of TUNEL-positive cells was revealed in treatment groups as compared to the control group. Serum antioxidant enzyme status was markedly decreased, whereas the liver MDA level was increased in TAC treatment groups indicating oxidative stress induction. The gene expression profile of cytokines was significantly upregulated in treatment groups highlighting an inflammatory response. In conclusion, results of the current study propose that even a short-term TAC exposure can induce change in antioxidant status and lipid peroxidation. Therefore, these factors should be considered to avoid and minimize immunosuppression-related issues in a prolonged course of treatment.

Regulatory B cells: TIM-1, transplant tolerance, and rejection

Regulatory B cells (Bregs) ameliorate autoimmune disease and prevent allograft rejection. Conversely, they hinder effective clearance of pathogens and malignancies. Breg activity is mainly attributed to IL-10 expression, but also utilizes additional regulatory mechanisms such as TGF-β, FasL, IL-35, and TIGIT. Although Bregs are present in various subsets defined by phenotypic markers (including canonical B cell subsets), our understanding of Bregs has been limited by the lack of a broadly inclusive and specific phenotypic or transcriptional marker. TIM-1, a broad marker for Bregs first identified in transplant models, plays a major role in Breg maintenance and induction. Here, we expand on the role of TIM-1⁺  Bregs in immune tolerance and propose TIM-1 as a unifying marker for Bregs that utilize various inhibitory mechanisms in addition to IL-10. Further, this review provides an in-depth assessment of our understanding of Bregs in transplantation as elucidated in murine models and clinical studies. These studies highlight the major contribution of Bregs in preventing allograft rejection, and their ability to serve as highly predictive biomarkers for clinical transplant outcomes.

Inhibition of Glycogen Synthase Kinase 3β Increases the Proportion and Suppressive Function of CD19+CD24hiCD27+ Breg Cells

CD19⁺CD24^hiCD27⁺ memory Breg cells exhibit decreased abundance in patients with chronic graft-versus-host disease (cGVHD) after liver transplantation and produce less IL-10 than those from patients without cGVHD and healthy donors. Due to the lack of Breg cells and the difficulty in expanding them in vitro, in mouse models and early human clinical trials, the adoptive transfer of Breg cells to autoimmune diseases is greatly restricted. Glycogen synthase kinase 3β (GSK-3β) is a multifunctional serine/threonine (ser/thr) protein kinase that can participate in B cell growth, metabolic activity, and proliferation. Phosphoprotein array analysis showed that p-GSK-3β-s9 was highly expressed in mBreg cells. Furthermore, here, we demonstrated that GSK-3β expression in mBreg cells is lower than that observed in B cells by flow cytometry. We found that the treatment of B cells with the specific GSK-3β inhibitor SB216763 can significantly increase the proportion and immunosuppressive function of mBreg cells in vitro. Nuclear factor of activated T cells (NFAT) is one of a pivotal regulator of gene expression in adaptive immune system. Here, we observed that inhibition of GSK-3β by SB216763 results in enhanced expression of NFATc1 in B cells, which is essential in regulating the ability of B cells to secrete IL-10. By constructing a xGVHD mouse model, we observed that SB216763-treated mBreg cells effectively prevent xenogeneic GVHD. Here we propose a novel strategy using SB216763 to inhibit GSK-3β and then enhance the proportion and immunosuppressive function of mBreg cells by increasing the expression of NFATc1. This approach may be used as a therapy to ameliorate GVHD and inflammatory diseases.

Regulatory B cells in transplantation: roadmaps to clinic

Over the last two decades, an additional and important role for B cells has been established in immune regulation. Preclinical studies demonstrate that regulatory B cells (Breg) can prolong allograft survival in animal models and induce regulatory T cells. Operationally tolerant human kidney transplant recipients demonstrate B-cell-associated gene signatures of immune tolerance, and novel therapeutic agents can induce Bregs in phase I clinical trials in transplantation. Our rapidly expanding appreciation of this novel B-cell subtype has made the road to clinical application a reality. Here, we outline several translational pathways by which Bregs could soon be introduced to the transplant clinic.

Strategies for Deliberate Induction of Immune Tolerance in Liver Transplantation: From Preclinical Models to Clinical Application

The liver exhibits intrinsic immune regulatory properties that maintain tolerance to endogenous and exogenous antigens, and provide protection against pathogens. Such an immune privilege contributes to susceptibility to spontaneous acceptance despite major histocompatibility complex mismatch when transplanted in animal models. Furthermore, the presence of a liver allograft can suppress the rejection of other solid tissue/organ grafts from the same donor. Despite this immune privilege of the livers, to control the undesired alloimmune responses in humans, most liver transplant recipients require long-term treatment with immune-suppressive drugs that predispose to cardiometabolic side effects and renal insufficiency. Understanding the mechanism of liver transplant tolerance and crosstalk between a variety of hepatic immune cells, such as dendritic cells, Kupffer cells, liver sinusoidas endothelial cells, hepatic stellate cells and so on, and alloreactive T cells would lead to the development of strategies for deliberate induction of more specific immune tolerance in a clinical setting. In this review article, we focus on results derived from basic studies that have attempted to elucidate the immune modulatory mechanisms of liver constituent cells and clinical trials that induced immune tolerance after liver transplantation by utilizing the immune-privilege potential of the liver.

Initial Dosage Recommendation for Sirolimus in Children With Tuberous Sclerosis Complex

Sirolimus is already used in the treatment of tuberous sclerosis complex (TSC), however, with narrow therapeutic range and considerable inter- and intra-individual pharmacokinetic variability, making it hard to develop an appropriate sirolimus initial dosage regimen, especially in children with TSC. The aim of this study was to recommend the optimal sirolimus initial dosing regimen in pediatric patients with TSC. Underlying physiological and genetic factors were collected to explore the effects on clinical sirolimus concentrations by establishing a nonlinear mixed effect (NONMEM) model, and to further simulate the optimal sirolimus initial dosing regimen using Monte Carlo method in pediatric patients with TSC. The once-daily regimen and the twice-daily regimen were recommended, respectively. For once-daily regimen, the dosages of 0.10, 0.07, 0.05, 0.04, 0.03 mg/kg/day were recommended for children with weights of 5–10, 10–20, 20–30, 30–50, and 50–60 kg, respectively. For twice-daily regimen, the dosages of 0.04, 0.03, 0.02 mg/kg/day (the daily dose was divided evenly into two doses) were recommended for children with weights of 5–20, 20–40, 40–60 kg, respectively. The initial dosages of sirolimus in children with TSC were recommended for the first time.