Immunosuppressive drugs and associated complications in abdominal organ transplantation

Cyclosporine combined with dexamethasone regulates hepatic Abca1 and PPARα expression and lipid metabolism via butyrate derived from the gut microbiota

Immunosuppression often leads to drastic metabolic, hormonal, and physiological disorders. Changes in the gut microbiota are believed to be one of the factors contributing to these disorders, but the association remains uncertain. Clinical studies can be complicated by confounding variables, such as diet and other drivers of heterogeneity in human microbiomes. In this study, we identified pronounced gut microbiome signatures in rhesus macaques (RMs) with immunosuppression-induced lipid metabolism disorders following cyclosporine combined with dexamethasone. Furthermore, we observed similar changes in the gut microbiota of mice with immunosuppression-induced lipid metabolism disorders, which were associated with short-chain fatty acid metabolism. ELISA showed that immunosuppression significantly reduced the levels of butyric acid in both feces and serum of mice. Spearman correlation analysis identified a significant correlation between serum butyric acid levels and gut microbial dysbiosis induced by immunosuppression, particularly in relation to f_Lachnospiraceae, g_unidentified_Ruminococcaceae, and s_Clostridium leptum. Additionally, mice transplanted with gut microbiota from immunosuppressed mice exhibited hepatic lipid metabolism disorders, and RNA sequencing revealed significant downregulation of ABC transporters and PPARα in the liver, which was closely associated with lipid transport and metabolism, particularly Abca1. Moreover, butyric acid supplementation alleviated hepatic lipid metabolism disorders and upregulated the expression of Abca1 and PPARα in mice transplanted with immunosuppression-induced gut microbiota. Thus, we propose that the combination of cyclosporine and dexamethasone regulates the expression of hepatic Abca1 and PPARα by modulating the gut microbiota and its derived butyrate, particularly Lachnospiraceae and Clostridium leptum, further regulating hepatic lipid metabolism.

Targeting TCMR-associated cytokine genes for drug screening identifies PPARγ agonists as novel immunomodulatory agents in transplantation

Objective

T cell-mediated rejection (TCMR) remains a significant challenge in organ transplantation. This study aimed to define a TCMR-associated cytokine gene set and identify drugs to prevent TCMR through drug repurposing.

Methods

Gene expression profiles from kidney, heart, and lung transplant biopsies were obtained from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) between TCMR and non-TCMR groups were identified, and their intersection with cytokine-related genes yielded an 11-gene TCMR-associated cytokine gene set (TCMR-Cs). To evaluate the effectiveness of this gene set, a diagnostic predictive model was constructed using Lasso regression and multivariate logistic regression, with validation in independent datasets. Connectivity Map (CMap) analysis was employed to screen drugs targeting TCMR-Cs. Experimental validation of the identified drug was performed in vitro using T cell activation and Th1 differentiation assays, and in vivo in a mouse skin transplant model with survival analysis.

Results

The TCMR-Cs exhibited outstanding predictive performance for TCMR, achieving an AUC of 0.99 in the training cohorts and maintaining strong performance in the test cohorts. CMap analysis identified peroxisome proliferator-activated receptor gamma (PPARγ) agonists as potential therapeutic candidates. Experimental validation showed that the PPARγ agonist rosiglitazone significantly suppressed T cell activation and reduced Th1 differentiation in vitro without cytotoxic effects. The combination of rosiglitazone and rapamycin significantly prolonged graft survival.

Conclusions

This study defined a novel TCMR-associated cytokine gene set that effectively predicts TCMR and identified PPARγ agonists, which prevent TCMR and improve graft survival when combined with rapamycin.

Anti-Inflammatory Effects of Ex Vivo-Generated Donor Antigen-Specific Immunomodulatory Cells on Pancreatic Islet Transplantation

Pancreatic islet transplantation (PITx) is a promising treatment option for patients with type 1 diabetes mellitus. Previously, we demonstrated that therapy with alloantigen-specific immunomodulatory cells (IMCs) generated ex vivo in the presence of anti-CD80 and CD86 monoclonal antibodies (mAbs), successfully induced tolerance following clinical liver transplantation. To extend IMC therapy to PITx, it is crucial to address the strong inflammatory and innate immune responses that occur immediately after PITx. In this study, we investigated the efficacy of IMCs in modulating macrophage activation and mitigating inflammatory damage of pancreatic islets. IMCs were induced using mouse splenocytes in the presence of anti-mouse anti-CD80 (RM80) and anti-CD86 (GL-1) mAbs. IMCs exerted donor-specific immunosuppressive effects in a mixed lymphocyte reaction. During lipopolysaccharide (LPS) stimulation, the addition of IMCs suppressed conversion to the M1 phenotype and promoted a shift toward the M2 phenotype, particularly under direct cell-cell contact conditions. Nitric oxide production, a hallmark of M1 polarized macrophages, was significantly reduced in LPS-stimulated RAW264 macrophages by IMC treatment. These findings were associated with reduced secretion of pro-inflammatory cytokines, tumoral necrosis factor α, and interleukin-6, and increased interleukin-10 production by macrophages. IMCs effectively prevented macrophage-mediated islet destruction after 12 h of co-culture with LPS-stimulated macrophages and significantly inhibited macrophage migration toward allogeneic islets in vitro. Intraportal co-infusion of IMCs with syngeneic islets in a mouse PITx model resulted in reduced messenger RNA (mRNA) expression of pro-inflammatory cytokines in the recipient liver. Immunohistochemical staining revealed a significantly lower number of F4/80+ macrophages at the transplantation site in IMCs-treated mice. These results demonstrate that IMCs modulate macrophage polarization, promoting a shift toward the M2 phenotype and protecting islets from macrophage-mediated damage. These effects combined with its intrinsic donor antigen-specific immunosuppressive capacity make IMC therapy a promising strategy for improving outcomes after PITx.

A Cohort Study of the Long-Term Influences of SARS-CoV-2 on Kidney Allograft Outcomes in Chinese Recipients: 1-Year Follow-Up Experience

Introduction

The aim of the study was to investigate the long-term effects of the novel severe acute respiratory syndrome coronavirus (SARS-CoV-2) infection and novel coronavirus disease (COVID-19) on prognosis of kidney transplant recipients.

Methods

A 1-year retrospective study was carried out among 362 domestic kidney transplant recipients who were divided into observational (COVID-19) and control groups. Stratification analysis was then carried out to investigate whether repeated infections and infection severity could influence graft prognosis. Kaplan-Meier curves assessed 1-year graft survival, while one-way analysis of variance (ANOVA) compared graft function and laboratory parameters. Generalized estimating equations and repeated-measures ANOVA confirmed the magnitude of the impact of COVID-19 on kidney grafts. Generalized logistic regression and Cox regression established a model for analyzing COVID-19 risk factors. Meta-analysis and subgroup analysis were performed for validation.

Results

Exposure of COVID-19 had a significant effect on graft function within 1 year (p < 0.001), and this kind of effect was mostly brought by severer infections in the stratification analysis regarding graft survival rate (p < 0.001), estimated glomerular filtration rate (eGFR) level (p < 0.001), and 1-year eGFR slope (p = 0.014). Diagnostic model showed tacrolimus patients are less likely to get severe COVID-19 than cyclosporine (p = 0.004). Hyperglycemia (p = 0.004) and low hemoglobin (p = 0.023) are adverse factors for severe pneumonia. Hemoptysis, hypo-lymphopenia, high procalcitonin and ferritin are linked to poor allograft outcomes with SARS-CoV-2 infection.

Conclusions

COVID-19 severity is linked to poor kidney allograft prognosis. Hyperglycemia, low hemoglobin, and drug protocols including cyclosporine rather than tacrolimus are correlated with COVID-19 pneumonia. Hemoptysis, low lymphocytes, high procalcitonin or ferritin were concerned with kidney allograft prognosis post-COVID-19.

Immune reactions following intestinal transplantation: Mechanisms and prevention

For patients with intestinal failure, small bowel transplantation remains one of the most effective treatments despite continuous advancements in parenteral nutrition techniques. Long-term use of parenteral nutrition can result in serious complications that lead to metabolic dysfunction and organ failure. However, the small intestine is a highly immunogenic organ with a large amount of mucosa-associated lymphoid tissue and histocompatibility antigens; therefore, the small intestine is highly susceptible to severe immune rejection. This article discusses the mechanisms underlying immune rejection after small bowel transplantation and presents various options for prevention and treatment. Our findings offer new insights into the development of small bowel transplantation.

Qualitative, rather than quantitative, differences between HLA-DQ alleles affect HLA-DQ immunogenicity in organ transplantation

Prolonging the lifespan of transplanted organs is critical to combat the shortage of this life-saving resource. Chronic rejection, with irreversible demise of the allograft, is often caused by the development of donor-specific HLA antibodies. Currently, enumerating molecular (amino acid) mismatches between recipient and donor is promoted to identify patients at higher risk of developing HLA antibodies, for use in organ allocation, and immunosuppression-minimization strategies. We have counseled against the incorporation of such approaches into clinical use and hypothesized that not all molecular mismatches equally contribute to generation of donor-specific immune responses. Herein, we document statistical shortcomings in previous study design: for example, use of individuals who lack the ability to generate donor-specific-antibodies (HLA identical) as part of the negative cohort. We provide experimental evidence, using CRISPR-Cas9-edited cells, to rebut the claim that the HLAMatchmaker eplets represent "functional epitopes." We further used unique sub-cohorts of patients, those receiving an allograft with two HLA-DQ mismatches yet developing antibodies only to one mismatch (2MM1DSA), to interrogate differential immunogenicity. Our results demonstrate that mismatches of DQα05-heterodimers exhibit the highest immunogenicity. Additionally, we demonstrate that the DQα chain critically contributes to the overall qualities of DQ molecules. Lastly, our data proposes that an augmented risk to develop donor-specific HLA-DQ antibodies is dependent on qualitative (evolutionary and functional) divergence between recipient and donor, rather than the mere number of molecular mismatches. Overall, we propose an immunological mechanistic rationale to explain differential HLA-DQ immunogenicity, with potential ramifications for other pathological processes such as autoimmunity and infections.

Caution to Poor Adherence With Immunosuppressant Medication That Causes Coma-Onset Autoimmune Encephalitis: A Case Report and Literature Review

Autoimmune encephalitis after liver transplantation (LT) is a rare disorder. This is because patients are usually in an immunosuppressed state after LT. Here, we report a rare case of autoantibody-negative autoimmune-encephalitis-induced coma after living-donor (LD) LT. A 45-year-old woman who underwent LDLT for primary biliary cholangitis (PBC) was brought to our hospital with the chief complaint of cognitive deficiency and an episode of memory loss. Physical examination, laboratory tests, and cerebrospinal fluid analysis revealed no significant findings. However, diffusion-weighted magnetic resonance imaging showed hyperintensity in the bilateral hippocampus. No autoantibodies associated with autoimmune encephalitis were detected. The diagnosis of antibody-negative autoimmune encephalitis was made on the basis of low immunosuppressive drug levels in the blood (indicative of poor adherence) and the presence of PBC as the autoimmune disease. The patient regained consciousness after intravenous methylprednisolone pulse therapy and plasma exchange. This case highlights that when examining patients with impaired consciousness after LDLT, it is important to consider autoimmune encephalitis as a potential diagnosis.

Reduction in Maintenance Immunosuppression in Kidney Transplant Recipients With Stable Donor-Derived Cell-Free DNA Measurements: A Case Series

Personalization of maintenance immunosuppression in kidney transplant recipients has long remained a goal in the transplant community. The recent addition of donor-derived cell-free DNA assays to detect allograft rejection and monitor allograft health may permit for reductions in maintenance immunosuppression in recipients with stable levels. Herein, we described 5 patients with stable donor-derived cell-free DNA levels who underwent reduction in maintenance immunosuppression without precipitation of clinical rejection, proteinuria, or de novo donor specific antibody formation.

Isolation, Expansion, and Endoscopic Delivery of Autologous Enteric Neuronal Stem Cells in Swine

The enteric nervous system (ENS) is an extensive network of neurons and glia within the wall of the gastrointestinal (GI) tract that regulates many essential GI functions. Consequently, disorders of the ENS due to developmental defects, inflammation, infection, or age-associated neurodegeneration lead to serious neurointestinal diseases. Despite the prevalence and severity of these diseases, effective treatments are lacking as they fail to directly address the underlying pathology. Neuronal stem cell therapy represents a promising approach to treating diseases of the ENS by replacing the absent or injured neurons, and an autologous source of stem cells would be optimal by obviating the need for immunosuppression. We utilized the swine model to address key questions concerning cell isolation, delivery, engraftment, and fate in a large animal relevant to human therapy. We successfully isolated neural stem cells from a segment of small intestine resected from 1-month-old swine. Enteric neuronal stem cells (ENSCs) were expanded as neurospheres that grew optimally in low-oxygen (5%) culture conditions. Enteric neuronal stem cells were labeled by lentiviral green fluorescent protein (GFP) transduction, then transplanted into the same swine from which they had been harvested. Endoscopic ultrasound was then utilized to deliver the ENSCs (10,000-30,000 neurospheres per animal) into the rectal wall. At 10 and 28 days following injection, autologously derived ENSCs were found to have engrafted within rectal wall, with neuroglial differentiation and no evidence of ectopic spreading. These findings strongly support the feasibility of autologous cell isolation and delivery using a clinically useful and minimally invasive technique, bringing us closer to first-in-human ENSC therapy for neurointestinal diseases.

Intensive care management of liver transplant recipients

PURPOSE OF REVIEW

Liver transplantation remains the only definitive treatment for advanced liver disease and liver failure. Current allocation schemes utilized for liver transplantation mandate a 'sickest first' approach, thus most liver transplants occur in patients with severe systemic illness. For intensive care providers who care for liver transplant recipients, a foundation of knowledge of technical considerations of orthotopic liver transplantation, basic management considerations, and common complications is essential. This review highlights the authors' approach to intensive care management of the postoperative liver transplant recipient with a review of common issues, which arise in this patient population.

RECENT FINDINGS

The number of centers offering liver transplantation continues to increase globally and the number of patients receiving liver transplantation also continues to increase. The number of patients with advanced liver disease far outpaces organ availability and, therefore, patients undergoing liver transplant are sicker at the time of transplant. Outcomes for liver transplant patients continue to improve owing to advancements in surgical technique, immunosuppression management, and intensive care management of liver disease both pretransplant and posttransplant.

SUMMARY

Given a global increase in liver transplantation, an increasing number of intensive care professionals are likely to care for this patient population. For these providers, a foundational knowledge of the common complications and key management considerations is essential.

From islet of Langerhans transplantation to the bioartificial pancreas

Type 1 diabetes is a disease resulting from autoimmune destruction of the insulin-producing beta cells in the pancreas. When type 1 diabetes develops into severe secondary complications, in particular end-stage nephropathy, or life-threatening severe hypoglycemia, the best therapeutic approach is pancreas transplantation, or more recently transplantation of the pancreatic islets of Langerhans. Islet transplantation is a cell therapy procedure, that is minimally invasive and has a low morbidity, but does not display the same rate of functional success as the more invasive pancreas transplantation because of suboptimal engraftment and survival. Another issue is that pancreas or islet transplantation (collectively known as beta cell replacement therapy) is limited by the shortage of organ donors and by the need for lifelong immunosuppression to prevent immune rejection and recurrence of autoimmunity. A bioartificial pancreas is a construct made of functional, insulin-producing tissue, embedded in an anti-inflammatory, immunomodulatory microenvironment and encapsulated in a perm-selective membrane allowing glucose sensing and insulin release, but isolating from attacks by cells of the immune system. A successful bioartificial pancreas would address the issues of engraftment, survival and rejection. Inclusion of unlimited sources of insulin-producing cells, such as xenogeneic porcine islets or stem cell-derived beta cells would further solve the problem of organ shortage. This article reviews the current status of clinical islet transplantation, the strategies aiming at developing a bioartificial pancreas, the clinical trials conducted in the field and the perspectives for further progress.