Immunosuppressive Agents and Infectious Risk in Transplantation: Managing the "Net State of Immunosuppression"

Vaccination strategies for solid organ transplant candidates and recipients: insights and recommendations

INTRODUCTION

Vaccines save lives. They are integral to reducing the morbidity and mortality of vaccine-preventable infections in solid organ transplant recipients. Pre-transplant vaccination provides a unique opportunity for administration of live, viral vaccines, and enhanced vaccine efficacy, compared to the post-transplant period with decreased vaccine response due to immunosuppression.

AREAS COVERED

We discuss a general approach to pre- and post-transplant vaccination in solid organ transplant candidates and recipients. We then review guideline statements and recent literature related to individual vaccines, including the recently developed respiratory syncytial virus vaccine. Travel and occupation-related vaccines are also discussed.

EXPERT OPINION

The challenge of vaccination for immunocompromised patients expands as the prevalence of immunocompromised adults rises, and immunocompromised patients are frequently excluded from vaccine trials. In an age of vaccine hesitancy and reemerging vaccine-preventable infections, well-powered, prospective studies are needed to evaluate the clinical effectiveness of vaccines in solid organ transplant candidates and recipients.

Human induced pluripotent stem cell-derived therapies for regeneration after central nervous system injury

In recent years, the progression of stem cell therapies has shown great promise in advancing the nascent field of regenerative medicine. Considering the non-regenerative nature of the mature central nervous system, the concept that "blank" cells could be reprogrammed and functionally integrated into host neural networks remained intriguing. Previous work has also demonstrated the ability of such cells to stimulate intrinsic growth programs in post-mitotic cells, such as neurons. While embryonic stem cells demonstrated great potential in treating central nervous system pathologies, ethical and technical concerns remained. These barriers, along with the clear necessity for this type of treatment, ultimately prompted the advent of induced pluripotent stem cells. The advantage of pluripotent cells in central nervous system regeneration is multifaceted, permitting differentiation into neural stem cells, neural progenitor cells, glia, and various neuronal subpopulations. The precise spatiotemporal application of extrinsic growth factors in vitro, in addition to microenvironmental signaling in vivo, influences the efficiency of this directed differentiation. While the pluri- or multipotency of these cells is appealing, it also poses the risk of unregulated differentiation and teratoma formation. Cells of the neuroectodermal lineage, such as neuronal subpopulations and glia, have been explored with varying degrees of success. Although the risk of cancer or teratoma formation is greatly reduced, each subpopulation varies in effectiveness and is influenced by a myriad of factors, such as the timing of the transplant, pathology type, and the ratio of accompanying progenitor cells. Furthermore, successful transplantation requires innovative approaches to develop delivery vectors that can mitigate cell death and support integration. Lastly, host immune responses to allogeneic grafts must be thoroughly characterized and further developed to reduce the need for immunosuppression. Translation to a clinical setting will involve careful consideration when assessing both physiologic and functional outcomes. This review will highlight both successes and challenges faced when using human induced pluripotent stem cell-derived cell transplantation therapies to promote endogenous regeneration.

Hydrogel injection molded complex macroencapsulation device geometry improves long-term cell therapy viability and function in the rat omentum transplant site

Insulin-secreting allogeneic cell therapies are a promising treatment for type 1 diabetes, with the potential to eliminate hypoglycemia and long-term complications of the disease. However, chronic systemic immunosuppression is necessary to prevent graft rejection, and the acute risks associated with immunosuppression limit the number of patients who can be treated with allogeneic cell therapies. Islet macroencapsulation in a hydrogel biomaterial is one proposed method to reduce or eliminate immune suppression; however, macroencapsulation devices suffer from poor oxygen transport and limited efficacy as they scale to large animal model preclinical studies and clinical trials. Hydrogel geometric device designs that optimize nutrient transport combined with methods to promote localized vasculogenesis may improve in vivo macroencapsulated cell viability and function. Here, we demonstrate with finite element modeling that a high surface area-to-volume ratio spiral geometry can increase macroencapsulated islet viability and function relative to a traditional cylindrical design, and we validate these observations in vitro under normoxic and physiological oxygen conditions. Finally, we evaluate macroencapsulated syngeneic islet survival and function in vivo in a diabetic rat omentum transplant model, and demonstrate that high surface area-to-volume hydrogel device designs improved macroencapsulated syngeneic islet function relative to traditional device designs.

Impact of immunosuppression medication management on short-term complications following sleeve gastrectomy

BACKGROUND

Sleeve gastrectomy (SG) is the most performed bariatric procedure in the United States due to its favorable safety profile. However, managing patients on chronic immunosuppressive therapy (CIT) during bariatric surgery poses challenges, particularly in balancing surgical outcomes with the risks associated with CIT interruption. This study aims to compare the short-term outcomes of SG in patients who temporarily discontinued CIT versus those who continued it perioperatively.

METHODS

A retrospective review was conducted of 75 patients on CIT who underwent SG at a single academic center between 2008 and 2022. Patients were categorized based on perioperative CIT management: 20 (26.7%) interrupted CIT and 55 (73.3%) continued therapy. Data on patient demographics, CIT indications, operative details, and short-term outcomes, including complications and readmissions, were analyzed.

RESULTS

The most common CIT indication was organ transplantation (61.4%), predominantly in the non-interruption group, while rheumatoid arthritis was the leading indication (50%) among patients who interrupted CIT. Early complications (≤ 30 days) were significantly higher in the non-interruption group (20% vs. 5%, p = 0.031), with bleeding being the most frequent (7 cases), followed by wound infections (4 cases). In contrast, the interruption group experienced only one complication, a wound infection. Weight outcomes were similar between groups, with no significant differences in percentage of total weight loss (%TWL) at 3 or 6 months. Notably, the interruption group had no 30-day readmissions or reoperations, compared to 16.4% and 5.5%, respectively, in the non-interruption group.

CONCLUSIONS

Temporary interruption of CIT in SG patients is associated with lower early complication rates and improved short-term outcomes. These findings highlight the importance of individualized perioperative CIT management and suggest potential benefits of CIT interruption when clinically feasible.

Impact of Severe Persistent BK Polyomavirus on Graft Function and Quality of Life Outcomes in Kidney Transplant Recipients

BACKGROUND

The risk factors and outcomes associated with severe persistent BK polyomavirus (BKPyV) in kidney transplant recipients (KTR) are unknown.

METHODS

This is a single-center retrospective study of KTR with severe persistent BKPyV compared to (1) KTR with low/no BKPyV-DNAemia and (2) KTR with high BKPyV-DNAemia. Severe persistent BKPyV was defined as BKPyV load reaching > 6 log10 (1 000 000 copies/mL) for ≥ 90 days. Low/no BKPyV was defined as BKPyV load remaining < 3 log10 (1000 copies/mL), and high BKPyV was defined as BKPyV load ≥ 3 log10 without meeting criteria for severe persistent BKPyV.

RESULTS

Out of 2586 KTR, 22 had severe persistent BKPyV and were compared to 1843 KTR with low/no BKPyV and 721 KTR with high BKPyV. A low absolute lymphocyte count during the first month posttransplant was associated with an increased risk of severe persistent BKPyV relative to those with low/no BKPyV and high BKPyV (OR 0.91, 95%CI 0.84, 0.99). KTR with severe persistent BKPyV had significantly lower eGFR at 2 years posttransplant relative to low/no and high BKPyV groups eGFR (36 vs. 61 and 59 mL/min; p < 0.001 for both). Additionally, KTR with severe persistent BKPyV required more lab draws and incurred significantly higher total lab-associated costs relative to KTR with low/no BKPyV and high BKPyV ($7516 vs. $4631, p < 0.001; $7516 vs. $5811, p < 0.001, respectively).

CONCLUSIONS

Severe persistent BKPyV is uncommon but associated with poor outcomes including impaired renal function, a higher burden of labs, and lab-associated costs. Future studies are needed to determine underlying factors that predict severe persistent BKPyV.

Duration of systemic antifungal therapy for patients with invasive fungal diseases: A reassessment

Invasive fungal diseases are associated with significant morbidity and mortality, especially among immunocompromised patients, and often prompt for rapid and aggressive treatment aiming cure. Due to the expanding magnitude of patients burdened by chronic immunosuppression and affected by fungal diseases, the diversity of clinical settings has risen. This often results in prolonged therapy (induction, consolidation and maintenance) associated with potentially severe side effects, and clinicians face the challenging decisions of when and how to stop anti-fungal therapy. Adequate duration of therapy is poorly defined, hampered by the lack of dedicated trials to the question, the heterogeneity of cases (type of fungal pathogen, localization of infection, underlying host conditions) and various confounding factors that may influence the clinical response (e.g. persistence vs recovery of immunosuppression, impact of surgery). In this review, we aim to evaluate the existing data underlying the guidelines and recommendations of treatment duration for the most frequent invasive fungal diseases (cryptococcal meningitis, Pneumocystis pneumonia, invasive aspergillosis, invasive candidiasis and mucormycosis), as well as specific localizations of deep-seated diseases (osteo-articular or central nervous system diseases and endocarditis) and emerging considerations and strategies.

Surveillance and prevention of infection in clinical xenotransplantation

SUMMARYXenotransplantation, the transplantation of living organs, tissues, or cells between species, carries the potential to address the global shortage of human organs for patients with end-stage organ failure. Recent advances in genetic engineering have improved prospects for clinical xenotransplantation by reducing immune and inflammatory responses to grafts, controlling coagulation on endothelial surfaces, and modifying viral risks, including the porcine endogenous retrovirus (PERV). Management of infectious risks posed by clinical xenotransplantation requires meticulous attention to the biosecure breeding and microbiological surveillance of source animals and recipients and consideration of novel infection control requirements. Infectious risks in xenotransplantation stem from both known human pathogens in immunosuppressed transplant recipients and from porcine organisms for which the clinical manifestations, microbial assays, and therapies are generally limited. Both known and unknown zoonoses may be transmitted from pigs to humans. Some pig-specific pathogens do not infect human cells but have systemic manifestations when active within the xenograft, including porcine cytomegalovirus/porcine roseolovirus (PCMV/PRV), which contributes to graft rejection and consumptive coagulopathy. The role of porcine endogenous retrovirus (PERV) in humans remains uncertain despite the absence of documented transmissions and the availability of swine with inactivated genomic PERV. New technologies, such as metagenomic sequencing and multi-omics approaches, will be essential for detection of novel infections and for understanding interactions between the xenograft, the host's immune system, and potential pathogens. These approaches will allow development of infection control protocols, pathogen surveillance requirements, and tailored antimicrobial therapies to enhance the safety and success of clinical xenotransplantation.

Sternal Osteomyelitis Caused by Mycobacterium tuberculosis in a Heart Transplant Patient

Mycobacterium tuberculosis (MT) infection poses a significant risk in immunocompromised individuals, particularly in areas with high MT prevalence. We describe the case of a 43-year-old heart transplant recipient who developed chronic sternal wound secretion post-transplant surgery. Imaging revealed signs of inflammatory tissue suggestive of chronic osteomyelitis. Removal of the sternal wires was performed, followed by biopsy, which identified granulomatous inflammatory tissue and Langhans cells, that led to the diagnosis of MT infection later confirmed in culture results. The patient completed a 6-month tetraconjugate antituberculous therapy, resulting in successful wound healing and infection resolution. Atypical extrapulmonary MT manifestations require high clinical suspicion, especially in immunocompromised patients, to ensure timely diagnosis and treatment with favorable outcomes.

Variation in acute cholecystitis outcomes and processes of care in patients with cancer

BACKGROUND

Patients undergoing active cancer therapy or with metastatic cancer are at increased risk for acute cholecystitis and often present to general surgeons for evaluation and management. There is a paucity of data regarding the treatment processes used in these patients and the clinical outcomes achieved. Optimal management of acute cholecystitis in patients with cancer requires understanding their unique risk profile and options for treatment.

METHODS

Emergency general surgery data were collected at 10 hospitals from July 1, 2019, to February 29, 2024. Patients presenting with acute cholecystitis were selected for analysis. Propensity score matching was used to create matched cohorts of patients by the presence or absence of an active malignancy. The primary outcome was 30-day mortality. Secondary outcomes included complications, length of stay, readmission, and discharge disposition. Processes investigated include treatment modality, time to operation, and surgical technique.

RESULTS

The analysis included 8,673 patients. Mean age was 53.2 ± 19 years, 61.4% were female, and 17.8% were non-White. In total, 3.3% of patients had an active malignancy. Risk-adjusted 30-day mortality was higher in the cancer cohort (odds ratio: 5.85, 95% confidence interval: 2.38-14.4, P < .001). Patients with cancer also had higher rates of infectious complications (odds ratio: 2.55, 95% confidence interval: 1.54-4.2, P < .001), including sepsis (odds ratio: 2.95, 95% confidence interval: 1.61-5.39, P < .001) and pneumonia (odds ratio: 6.67, 95% confidence interval: 1.75-25.3, P < .005). Patients with cancer were more likely to receive nonoperative management (odds ratio: 2.85, 95% confidence interval: 2.11-3.84, P < .001).

CONCLUSION

Patients with cancer presenting with acute cholecystitis experience worse clinical outcomes after controlling for other factors. Furthermore, there is variation in the treatment process with increased rates of nonoperative management. These results have implications for the management of this population, particularly in relation to the impact on concurrent oncologic treatment plans.

The use of virtual reality-assisted interventions on psychological well-being and treatment adherence among kidney transplant recipients: A randomized controlled study

This randomized controlled trial aims to investigate the effects of educational and psychological interventions on the health outcomes of patients suffering from chronic diseases. We recruited 372 patients and randomly assigned them to one of two intervention arms during the trial, which lasted for a year. Both groups participated in a 12-month intervention program, where the intervention group received health education and supportive psychological therapy utilizing virtual reality (VR) technology, while the control group received conventional health education guidance. Statistical analysis showed that compared to the control group, the intervention group demonstrated significant improvements (p < 0.05) in depression assessment scores, compliance scores, and Barthel functional scoring. However, the two groups had no significant difference in the incidence of complications and health knowledge mastery. Additionally, the intervention group had fewer hospitalization days than the control group, with statistically significant differences. The research results prove that targeted intervention effectively improves medication adherence, patient awareness, and reduces patient hospitalization days, which is particularly important for managing chronic diseases.

Pulmonary Immunocompromise in Solid Organ Transplantation

This article reviews the multitude of factors contributing to immune dysfunction and pulmonary infection risk in solid organ transplant recipients and references relevant clinical scientific reports. The mechanisms of action of individual immunosuppressive agents are explained, and the clinical effects of these drugs are compared. In addition, specialized methods to assess the net state of immunosuppression in individual transplant recipients and their limitations are discussed.

S1PR1-biased activation drives the resolution of endothelial dysfunction-associated inflammatory diseases by maintaining endothelial integrity

G protein-coupled sphingosine-1-phosphate receptor 1 (S1PR1), a drug target for inflammatory bowel disease (IBD), enables immune cells to egress from lymph nodes, but the treatment increases the risk of immunosuppression. The functional signaling pathway triggered by S1PR1 activation in endothelial cells and its therapeutic application remains unclear. Here, we showed that S1PR1 is highly expressed in endothelial cells of IBD patients and positively correlated with endothelial markers. Gi-biased agonist-SAR247799 activated S1PR1 and reversed pathology in male mouse and organoid IBD models by protecting the integrity of the endothelial barrier without affecting immune cell egress. Cryo-electron microscopy structure of S1PR1-Gi signaling complex bound to SAR247799 with a resolution of 3.47 Å revealed the recognition mode for the biased ligand. With the efficacy of SAR247799 in treating other endothelial dysfunction-associated inflammatory diseases, our study offers mechanistic insights into the Gi-biased S1PR1 agonist and represents a strategy for endothelial dysfunction-associated disease treatment.

Strategies for preventing and reducing the impact of acute respiratory failure from pneumonia

INTRODUCTION

Pneumonia remains a leading cause of morbidity and mortality, particularly in critically ill patients with acute respiratory failure (ARF). This review discusses prevention strategies for pneumonia-induced ARF, categorized into primary, secondary, and tertiary prevention.

AREAS COVERED

A literature search was conducted through PubMed covering the years 2000-2024, using the keywords 'acute respiratory failure,' pneumonia prevention," 'risk stratification,' and 'preventive strategies.' Primary prevention focuses on reducing pneumonia risk through vaccination, smoking cessation, and comorbidity management. Secondary prevention involves early detection, risk assessment using clinical tools like the Pneumonia Severity Index (PSI) biomarkers, such as procalcitonin and C-reactive protein, appropriate antibiotic use, and emerging machine learning tools for real-time stratification. Tertiary prevention focuses on optimizing care with noninvasive respiratory support, lung-protective ventilation strategies, and ventilator bundles for intubated patients. Emerging therapies, including targeted use of corticosteroids and other immunomodulatory agents, are also discussed as promising adjuncts to current standards of care.

EXPERT OPINION

While these prevention strategies show potential, continued research is necessary to refine these interventions, explore newer therapies and evaluate long-term outcomes. Implementation of these strategies aims to reduce the impact of pneumonia-induced ARF on healthcare systems and improve patient survival and quality of care.

Optimizing hepatitis B virus seroprotection in thoracic organ transplantation: The role of HepB-CpG (Heplisav-B) vaccination schedule

INTRODUCTION

Heplisav-B, a CpG-adjuvanted recombinant hepatitis B virus (HBV) vaccine, has a higher seroprotection rate and immunogenicity than the conventional HBV vaccine. This study aimed to identify the predictors of HBV seroprotection post-transplantation in thoracic organ transplant recipients who received Heplisav-B.

METHODS

We conducted a retrospective study of adult thoracic organ (heart and lung) transplant recipients at Mayo Clinic sites in Minnesota, Arizona, and Florida between January 2020 and August 2023. Patients who completed Heplisav-B series were classified into three strategies: strategy A (completed 2 doses of Heplisav-B pre-transplantation with achieved seroprotection pre-transplantation), strategy B (received first dose of Heplisav-B pre-transplantation and second dose of Heplisav-B post-transplantation), and strategy C (completed 2 doses of Heplisav-B post-transplantation). HBV seroprotection was defined as HBsAb ≥10 IU/L.

RESULTS

A total of 154 thoracic organ transplant recipients completed Heplisav-B vaccine series. Post-transplant seroprotection was highest in strategy A, followed by strategy B and strategy C (54/76 [71 %] vs. 18/39 [46 %] vs. 14/39 [36 %]; p < 0.001). Multivariate logistic regression analysis identified two independent factors predicting lack of HBV seroprotection post-transplantation; both were related to Heplisav-B schedule: strategy B (adjusted odds ratio [aOR], 2.482; 95 % confidence interval [CI] 1.085 5.679; p = 0.031), and strategy C (aOR 4.963; 95 % CI 2.106 11.697; p < 0.001).

CONCLUSION

The vaccine schedule significantly predicts HBV seroprotection in adult thoracic organ transplant recipients. Our data supports the recommendation that pre-transplantation Heplisav-B to achieve HBsAb ≥10 IU/L is the optimal vaccination schedule to maintain an HBsAb level of ≥10 IU/L post-transplantation. Further studies are needed to determine whether this observation can be replicated in non-thoracic organ transplant recipients or pediatric populations.

Clinical Management and Outcomes of Nontuberculous Mycobacterial Infections in Solid Organ Transplant Recipients: A Multinational Case-control Study

BACKGROUND

The management and outcomes of nontuberculous mycobacterial (NTM) infections in solid organ transplant (SOT) recipients are poorly characterized. We aimed to describe the management and 1-y mortality of these patients.

METHODS

Retrospective, multinational, 1:2 matched case-control study included SOT recipients aged 12 y old or older diagnosed with NTM infection between January 1, 2008, and December 31, 2018. Controls were matched on transplanted organs, NTM treatment center, and posttransplant survival at least equal to the time to NTM diagnosis. The primary aim was 1-y mortality after NTM diagnosis. Differences between cases and controls were compared using the log-rank test, and Cox regression models were used to identify factors associated with mortality at 12 mo among cases.

RESULTS

In 85 patients and 169 controls, the median age at the time of SOT was 54 y (interquartile range, 40-62 y), 59% were men, and the lungs were the most common site of infection after SOT (57.6%). One-year mortality was significantly higher in cases than in controls (20% versus 3%; P < 0.001), and higher mortality was associated with lung transplantation (hazard ratio 3.27; 95% confidence interval [1.1-9.77]; P = 0.034). Median time (interquartile range) from diagnosis to treatment initiation (20 [4-42] versus 11 [3-21] d) or the reduction of net immunosuppression (36% versus 45%, hazard ratio 1.35 [95% CI, 0.41-4.43], P = 0.618) did not differ between survivors and those who died.

CONCLUSIONS

NTM disease in SOT recipients is associated with a higher mortality risk, especially among lung transplant recipients. Time to NTM treatment and reduction in net immunosuppression were not associated with mortality.

Increased Risk of Postoperative Complications in Organ Transplant Recipients Undergoing Mohs Micrographic Surgery

BACKGROUND

Solid organ transplant recipients (SOTRs) are at increased risk of developing nonmelanoma skin cancers (NMSC), which may require treatment by Mohs micrographic surgery (MMS). Previous small-scale studies yielded conflicting findings on post-MMS complications in immunosuppressed individuals, and large-scale population-based analyses for SOTRs undergoing MMS are lacking.

OBJECTIVE

The authors investigate postoperative complications after MMS in SOTRs using the TriNetX database of over 106 million patients in the US Collaborative Network.

MATERIALS AND METHODS

Among MMS recipients in this database, a cohort of organ transplant recipients and a cohort of immunocompetent patients were generated. Immunosuppressive medications other than antirejection medications for the SOTR cohort were excluded from both groups. The outcomes for common postoperative complications including infection, wound disruption, graft failure, bleeding, rash, disturbance of skin sensation, and hypertrophic scarring were assessed during a 60-day postoperative window.

RESULTS

SOTRs exhibit a twofold increased risk of postoperative infection, 2.5-fold increased risk of surgical wound disruption, and over threefold increased likelihood of swelling within 60 days post-MMS compared with immunocompetent patients. There was no significant difference in bleeding between the cohorts.

CONCLUSION

Given these findings, it may be worth assessing the role of antibiotics and close monitoring for the SOTR population in larger prospective studies to inform future surgical guidelines.

Diagnosis and Prevention of Invasive Fungal Infections in the Immunocompromised Host

TOPIC IMPORTANCE

The prevalence of invasive fungal infections (IFIs) has risen in the past 3 decades, attributed to advancements in immune-modulatory therapies used in transplantation, rheumatology, and oncology.

REVIEW FINDINGS

Organisms that cause IFI evade the host's natural defenses or at opportunities of immunologic weakness. Infections occur from inhalation of potentially pathogenic organisms, translocation of commensal organisms, or reactivation of latent infection. Organisms that cause IFI in immunocompromised populations include Candida species, Cryptococcus species, environmental molds, and endemic fungi. Diagnosis of these infections is challenging due to slow organism growth and fastidious culture requirements. Moreover, fungal biomarkers tend to be nonspecific and can be negatively impacted by prophylactic antifungals. Antibody-based tests are not sensitive in immunocompromised hosts making antigen-based testing necessary. Prevention of IFI is guided by pathogen avoidance, removal or minimization of immune-suppressing factors, and pharmacologic prophylaxis in select hosts.

SUMMARY

Understanding the complex interplay between the immune system and opportunistic fungal pathogens plays a key role in early diagnosis and prevention.

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.

Fungal Infections in Kidney Transplant Recipients: A Comprehensive Narrative Review

BACKGROUND

Despite kidney transplantation being a life-saving procedure, patients experience a high risk of developing fungal infections (FIs), with an increased risk of both morbidity and mortality, especially during the first year after transplant.

METHODS

We herein conducted a narrative review of the most common FIs in kidney transplant recipients (KTRs), with a focus on prevalence, risk factors, mortality, and prevention strategies.

RESULTS

The most common fungal pathogens in KTRs include Candida species (up to 70% of the overall FIs), Aspergillus species, Pneumocystis jiroveci, and Cryptococcus species. Fungal colonization, diabetes mellitus, chronic liver disease, malnutrition, and pre-existing lung conditions should all be acknowledged as possible predisposing risk factors. The mortality rate can vary from 25 to 50% and according to different settings and the types of FIs. Preventive strategies are critical for reducing the incidence of FIs in this population. These include antifungal prophylaxis, environmental precautions, and infection control measures. The use of novel tools (such as PCR-based molecular assays and NGS) for rapid and accurate diagnosis may play an important role.

CONCLUSIONS

Early recognition, the appropriate use of antifungal therapy, and preventive strategies are essential for improving graft loss and fatal outcomes in this vulnerable population. Future research is needed to optimize diagnostic tools, identify novel antifungal agents, and develop better prophylactic strategies for high-risk transplant recipients.

Harnessing cellular therapeutics for type 1 diabetes mellitus: progress, challenges, and the road ahead

Type 1 diabetes mellitus (T1DM) is a growing global health concern that affects approximately 8.5 million individuals worldwide. T1DM is characterized by an autoimmune destruction of pancreatic β cells, leading to a disruption in glucose homeostasis. Therapeutic intervention for T1DM requires a complex regimen of glycaemic monitoring and the administration of exogenous insulin to regulate blood glucose levels. Advances in continuous glucose monitoring and algorithm-driven insulin delivery devices have improved the quality of life of patients. Despite this, mimicking islet function and complex physiological feedback remains challenging. Pancreatic islet transplantation represents a potential functional cure for T1DM but is hindered by donor scarcity, variability in harvested cells, aggressive immunosuppressive regimens and suboptimal clinical outcomes. Current research is directed towards generating alternative cell sources, improving transplantation methods, and enhancing cell survival without chronic immunosuppression. This Review maps the progress in cell replacement therapies for T1DM and outlines the remaining challenges and future directions. We explore the state-of-the-art strategies for generating replenishable β cells, cell delivery technologies and local targeted immune modulation. Finally, we highlight relevant animal models and the regulatory aspects for advancing these technologies towards clinical deployment.

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.

Epidemiology of Infections in Lung Transplant Recipients Treated With Belatacept

BACKGROUND

Belatacept is a costimulatory blocker that can be used to prevent and treat rejection in lung transplant recipients (LuTRs). The epidemiology of infections in belatacept-treated LuTRs has not been systematically evaluated.

METHODS

We performed a single-center retrospective study of all adult LuTRs who received belatacept as prevention or treatment of antibody-mediated rejection (desensitization) or as part of maintenance immunosuppression from January 1, 2011, to June 30, 2022. We assessed the epidemiology of infections that occurred within 12 months following the first belatacept dose.

RESULTS

Fifty-two LuTRs received at least one dose of belatacept as either desensitization (n = 32) or maintenance immunosuppression (n = 20). Among 45 patients who were cytomegalovirus (CMV) donor and/or recipient seropositive, nine (20%) developed CMV infection. Seven (77%) CMV infections occurred despite valganciclovir prophylaxis and four (44%) were associated with antiviral resistance. Three (6%) LuTRs developed Epstein-Barr virus (EBV) associated post-transplant lymphoproliferative disorder (PTLD). Twenty-five (48%) LuTRs developed 43 bacterial infections and five (10%) developed proven or probable invasive fungal disease. Incidence rates of viral, bacterial, and fungal infections were similar between the desensitization and maintenance groups: incidence rate ratios (95% confidence interval) were 0.70 (0.32-1.57), 1.31 (0.70-2.46), and 2.82 (0.31-25.2), respectively. Infection/PTLD prompted belatacept discontinuation in eight (15%) patients.

CONCLUSIONS

In the first year after belatacept initiation, LuTRs commonly developed CMV infections, EBV+ PTLD, and bacterial infections. Multicenter collaborations are needed to better understand infection risks in LuTRs treated with belatacept.

ANCA-Associated Glomerulonephritis: Diagnosis and Therapy Proceedings of the Henry Shavelle Lectureship

Background

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) frequently affects the kidney. Glomerulonephritis (GN) in AAV, ANCA-GN, not only dictates therapeutic decisions but is also of relevance for overall survival influencing the risk of cardiovascular disease and serious infections.

Summary

A diagnosis of ANCA-GN includes laboratory investigations including urinalysis and a thorough assessment of potential organ involvement. A kidney biopsy can be performed to ascertain the diagnosis but has an additional prognostic relevance and tools have been established to predict long-term kidney survival. Experimental biomarkers indicating kidney inflammation include urinary soluble CD163 and the presence of urinary T cells. Therapeutic options are refined and some of these therapies, such as the added value of performing plasma exchange, are the matter of controversial discussions. Safe reduction of cumulative exposure to glucocorticoids and eventually the use of avacopan to substantially reduce glucocorticoid exposure has been implemented in most centers. In the remission of maintenance, the optimal duration of therapy is still unclear, but extended use of rituximab as maintenance agent has shown long-term remission rates, thus limiting the damage accrued by relapsing disease and thus also reducing the risk of end-stage kidney disease (ESKD). Avacopan has been the first agent with a glomerular filtration rate-sparing effect, likely due to more rapid control of kidney inflammation. Those reaching ESKD should be evaluated for kidney transplantation and the risk of remaining on dialysis must be balanced against the risk of recurrence of disease following transplantation.

Key Messages

The advent of a magnitude of landmark studies in ANCA-GN has refined diagnostic approaches, implemented tools to predict kidney outcome, and eventually led to the approval of newer therapies with avacopan, the latest addition to the armamentarium. Once ESKD is present, patients should be considered for kidney transplantation as remaining on dialysis portends poor overall prognosis.

Advancements and Challenges in Immune Protection Strategies for Islet Transplantation

Pancreatic islet transplantation is a crucial treatment for managing type 1 diabetes (T1D) in clinical settings. However, the limited availability of human cadaveric islet donors and the need for ongoing administration of immunosuppressive agents post-transplantation hinder the widespread use of this treatment. Stem cell-derived islet organoids have emerged as an effective alternative to primary human islets. Nevertheless, implementing this cell replacement therapy still requires chronic immune suppression, which may result in life-long side effects. To address these challenges, innovations such as encapsulation devices, universal stem cells, and immunomodulatory strategies are being developed to mitigate immune rejection and prolong the function of the transplant. This review outlines the contemporary challenges in pancreatic β cell therapy, particularly immune rejection, and recent progress in immune-isolation devices, hypoimmunogenic stem cells, and immune regulation of transplants. A comprehensive evaluation of the advantages and limitations of these approaches will contribute to improved future clinical investigations. With these promising advancements, the application of pancreatic β cell therapy holds the potential to effectively treat T1D and benefit a larger population of T1D patients.

Epidemiology and pathogen characteristics of infections following solid organ transplantation

Solid organ transplantation (SOT) recipients have a heightened risk for infection due to prolonged immunosuppressive drug use following transplant procedures. The occurrence of post-transplant infections is influenced not only by the transplanted organ type but also by varied factors. The kidney is the most common organ in SOT, followed by the liver, heart, and lung. This review aims to provide a comprehensive overview of the current epidemiological characteristics of infections after kidney, liver, heart, and lung transplantation, focusing on bacterial, fungal, and viral infections. The incidence and infection types demonstrated significant variability across different SOTs. Furthermore, this review attempts to elucidate the clinical characteristics of infections across patients following different SOTs and contribute to the development of individualized prevention strategies according to infection incidence, ultimately enhancing the quality of life of transplant recipients.

Schwann cell autotransplantation for the treatment of peripheral nerve injury

Peripheral nerve injury occurs in a relatively large proportion of trauma patients, in whom it generally results in severe functional impairment and permanent disability. At present, however, there are no effective treatments available. Studies have shown that Schwann cells play an indispensable role in removing myelin debris and guiding axonal regeneration, and transplantation using autologous Schwann cells has shown good efficacy for patients with peripheral nerve injury. In recent years, Schwann cell autologous transplantation therapy has become an area of intensive research and is anticipated to provide a new strategy for the clinical treatment of peripheral nerve injury. In this article, we review the rationale for selecting Schwann cell autotransplantation therapy and the latest progress in key aspects of cell transplantation and clinical efficacy, and also summarize the future directions of research on this therapy. All of the above provide a strong basis for the further improvement and clinical promotion of this therapy.

Epstein-Barr Virus Infection Presenting With Acute Gastrointestinal Involvement. Report of Two Cases of Epstein-Barr Virus Colitis in Kidney-Transplant Recipients and Scoping Review of the Literature

Epstein-Barr virus (EBV) is a herpesvirus capable of establishing lifelong latent infections, leading to a wide spectrum of diseases. It can affect multiple organs, including the gastrointestinal tract, typically through lymphoproliferative syndromes or gastric cancer, while acute gastrointestinal disease is rare and poorly understood. Two cases of EBV-induced acute colitis in kidney transplant recipients were described. Additionally, a scoping review of the literature was conducted to identify all reported cases of EBV infection presenting with acute gastrointestinal involvement. A total of 11 174 articles from PubMed and Embase were analyzed, from which 30 articles were ultimately selected, encompassing 33 cases. Two distinct patient profiles emerged. Patients with gastric-limited disease were typically healthy women and exhibited a benign course, characterized by a more acute presentation and complete recovery in all cases. In contrast, patients with intestinal disease were often immunocompromised, presenting with deep colonic ulcers frequently associated with rectal bleeding, high rates of perforation, frequent need for surgical intervention, and significant mortality. Antiviral therapy and reduction of immunosuppression were commonly employed, although no specific treatment approach demonstrated a clear benefit in reducing mortality or complications. In conclusion, EBV-related gastrointestinal disease varies by patient immunocompetence and the site of involvement. Gastric-limited disease usually has a favorable prognosis, while intestinal involvement in immunocompromised patients is linked to severe complications and higher mortality. Individualized treatment strategies and vigilant long-term follow-up are needed due to the lack of standardized treatment protocols and the risk of relapse or development of EBV-associated lymphoproliferative disorders.

Impact of COVID-19 Omicron variant on lung transplantation patients with 1-year follow-up: A single tertiary medical center experience

BACKGROUND

Lung transplantation patients with coronavirus disease 2019 (COVID-19) have high mortality. However, the impact of the Omicron variant in lung transplantation patients is unclear. This study focuses on lung transplant patients diagnosed with COVID-19 during the Omicron wave, and investigate the clinical presentations, outcomes and pulmonary function.

METHODS

In this single-center retrospective study, we enrolled lung transplantation patients diagnosed with COVID-19 from January 2022 to December 2022. Demographic, laboratory and pulmonary function data were recorded. Pre-COVID-19 pulmonary function data were obtained from the closest routine test, and post-COVID-19 tests were arranged after release from isolation.

RESULTS

Of the 22 enrolled patients, four were admitted to general wards for treatment and observation, and two needed oxygen support. All of the patients recovered from COVID-19. There were no significant decreases in forced vital capacity (FVC) (2.3 ± 0.6 vs. 2.2 ± 0.8 L, p = 0.363) and forced expiratory volume in the first second (FEV1) (2.0 ± 0.6 vs. 1.9 ± 0.8 L, p = 0.269) after COVID-19 infection. Daily prednisolone dose and serum tacrolimus levels were significantly correlated to the duration of positive COVID-19 test and change in FEV1. Patients who did not receive a booster dose of COVID-19 vaccination had a significantly longer positive test duration (9.1 ± 4.1 vs. 26.6 ± 24.4 days, p = 0.05), and greater decrease in FEV1 (23.6 ± 137.3 vs. -331.8 ± 537.8 L, p = 0.040).

CONCLUSIONS

In this study, lung transplant patients infected with COVID-19 during the Omicron wave had low rate of severe disease and mortality. Immunosuppressive medications and COVID-19 vaccination were correlated with viral clearance and pulmonary function after COVID-19 infection.

Current and emerging tools for simultaneous assessment of infection and rejection risk in transplantation

Infection and rejection are major complications that impact transplant longevity and recipient survival. Balancing their risks is a significant challenge for clinicians. Current strategies aimed at interrogating the degree of immune deficiency or activation and their attendant risks of infection and rejection are imprecise. These include immune (cell counts, function and subsets, immunoglobulin levels) and non-immune (drug levels, viral loads) markers. The shared risk factors between infection and rejection and the bidirectional and intricate relationship between both entities further complicate transplant recipient care and decision-making. Understanding the dynamic changes in the underlying net state of immunity and the overall risk of both complications in parallel is key to optimizing outcomes. The allograft biopsy is the current gold standard for the diagnosis of rejection but is associated with inherent risks that warrant careful consideration. Several biomarkers, in particular, donor derived cell-free-DNA and urinary chemokines (CXCL9 and CXCL10), show significant promise in improving subclinical and clinical rejection risk prediction, which may reduce the need for allograft biopsies in some situations. Integrating conventional and emerging risk assessment tools can help stratify the individual's short- and longer-term infection and rejection risks in parallel. Individuals identified as having a low risk of rejection may tolerate immunosuppression wean to reduce medication-related toxicity. Serial monitoring following immunosuppression reduction or escalation with minimally invasive tools can help mitigate infection and rejection risks and allow for timely diagnosis and treatment of these complications, ultimately improving allograft and patient outcomes.

TIM proteins and microRNAs: distinct impact and promising interactions on transplantation immunity

Achieving sustained activity and tolerance in of allogeneic grafts after post-transplantation remains a substantial challenge. The response of the immune system to "non-self" MHC-antigenic peptides initiates a crucial phase, wherein blocking positive co-stimulatory signals becomes imperative to ensure graft survival and tolerance. MicroRNAs (miRNAs) inhibit mRNA translation or promote mRNA degradation by complementary binding of mRNA seed sequences, which ultimately affects protein synthesis. These miRNAs exhibit substantial promise as diagnostic, prognostic, and therapeutic candidates for within the realm of solid organ transplantations. Current research has highlighted three members of the T cell immunoglobulin and mucin domain (TIM) family as a novel therapeutic avenue in transplantation medicine and alloimmunization. The interplay between miRNAs and TIM proteins has been extensively explored in viral infections, inflammatory responses, and post-transplantation ischemia-reperfusion injuries. This review aims to elucidate the distinct roles of miRNAs and TIM in transplantation immunity and delineate their interdependent relationships in terms of targeted regulation. Specifically, this investigation sought seeks to uncover the potential of miRNA interaction with TIM, aiming to induce immune tolerance and bolster allograft survival after transplantation. This innovative strategy holds substantial promise in for the future of transplantation science and practice.

Risk factors for SARS-CoV-2 infection and severe COVID-19 in unvaccinated solid organ transplant recipients

The role of immunosuppressive therapy on SARS-CoV-2 infection risk and COVID-19 severity remains unclear in unvaccinated solid organ transplant recipients. We included 1957 organ transplant recipients between July 2020 and April 2021 to analyze whether baseline immunosuppressive therapy and other risk factors are associated with SARS-CoV-2 infection and severe COVID-19. In total, 247 (12.6%) had SARS-CoV-2 (defined as positive nasopharyngeal swab and/or positive antibody titer). Of these, 57 (23.1%) had severe COVID-19, defined as oxygen supplementation, intensive care unit admission or death. Multivariable analysis identified diabetes (hazard ratio (HR) 1.39 (95% confidence interval (CI) 1.05-1.83)), chronic lung disease (HR 1.71 (95% CI 1.13-2.60)) and contact with a COVID-19 positive individual (HR 3.61 (95% CI 2.61-4.99) as independent risk factors for SARS-CoV-2 infection. There was no association between immunosuppressive therapy and infection risk. Severe COVID-19 was multivariably associated with hypertension (OR 5.45 (95% CI 1.66-17.84)), chronic kidney disease (OR 3.55 (95% CI 1.75-7.19)), corticosteroid use (OR 2.93 (95% CI 1.03-2.55)) and having a COVID-19 positive housemate (OR 6.77 (95% CI 2.65-17.28)). In conclusion, baseline corticosteroid use, but no other immunosuppressive agent, is independently associated with severe COVID-19 in unvaccinated SOT recipients after correction for hypertension, chronic kidney disease, housemates affected by COVID-19 and transplant type.

Nanoparticle-assisted Targeting Delivery Technologies for Preventing Organ Rejection

Although organ transplantation is a life-saving medical procedure, the challenge of posttransplant rejection necessitates safe and effective immune modulation strategies. Nanodelivery approaches may have the potential to overcome the limitations of small-molecule immunosuppressive drugs, achieving efficacious treatment options for transplant tolerance without compromising overall host immunity. This review highlights recent advances in biomaterial-assisted formulations and technologies for targeted nanodrug delivery with transplant organ- or immune cell-level precision for treating graft rejection after transplantation. We provide an overview of the mechanism of transplantation rejection, current clinically approved immunosuppressive drugs, and their relevant limitations. Finally, we discuss the targeting principles and advantages of organ- and immune cell-specific delivery technologies. The development of biomaterial-assisted novel therapeutic strategies holds considerable promise for treating organ rejection and clinical translation.

The American Association of Tissue Banks tissue donor screening for Mycobacterium tuberculosis-Recommended criteria and literature review

After two multistate outbreaks of allograft tissue-transmitted tuberculosis (TB) due to viable bone, evidence-based donor screening criteria were developed to decrease the risk of transmission to recipients. Exclusionary criteria, commentary, and references supporting the criteria are provided, based on literature search and expert opinion. Both exposure and reactivation risk factors were considered, either for absolute exclusion or for exclusion in combination with multiple risk factors. A criteria subset was devised for tissues containing viable cells. Risk factors for consideration included exposure (e.g., geographic birth and residence, travel, homelessness, incarceration, healthcare, and workplace) and reactivation (e.g., kidney disease, liver disease, history of transplantation, immunosuppressive medications, and age). Additional donor considerations include the possibility of sepsis and chronic illness. Donor screening criteria represent minimal criteria for exclusion and do not completely exclude all possible donor TB risks. Additional measures to reduce transmission risk, such as donor and product testing, are discussed but not included in the recommendations. Careful donor evaluation is critical to tissue safety.

Epstein-Barr virus-specific T-cell response in pediatric liver transplant recipients: a cross-sectional study by multiparametric flow cytometry

Background

Epstein-Barr virus (EBV) specific T-cell response measurement can help adjust immunosuppression in transplant patients with persistent infections. We aim to define T-cell responses against EBV in a cohort of pediatric liver-transplant patients.

Methods

Thirty-eight immunosuppressed pediatric liver-transplant patients (IP) and 25 EBV-seropositive healthy-adult controls (HC) were included in our cross-sectional study. Based on their EBV serological (S) and viral load (VL) status, patients were categorized into IP-SNEG, IP-SPOSVLNEG and IP-SPOSVLPOS groups. T-cell response was assessed at two timepoints by stimulating cells with EBV peptides (PepTivator®) and performing intracellular-cytokine and activation-induced marker staining. Background subtraction was used to determine EBV-specific T-lymphocyte frequency.

Results

Polyfunctional CD8+ T cells indicated previous EBV contact (IP-SNEG 0.00% vs IP-SPOS 0.04% and HC 0.02%; p=0.001 and p=0.01, respectively). Polyfunctional CD8+CD107a+IFNɣ+IL2-TNFα- profile was increased in serology-positive (IP-SNEG 0.01% vs IP-SPOS 0.13% and HC 0.03%; p=0.01 and p=0.50, respectively) and viral-load positive (IP-SPOSVLPOS 0.43% vs IP-SPOSVLNEG 0.07% and HC 0.03%; p=0.03 and p=0.001, respectively) patients. Central-memory cells were increased among serology-positive adults (IP-SNEG 0.00% vs IP-SPOS 0.13% and HC 4.33%; p=0.58 and p=0.002, respectively). At the second timepoint, IP-SNEG patients remained negative (first visit 0.01% vs second visit 0.00%, p=0.44). On the other hand, IP-SPOSVLPOS patients had cleared viral loads and, subsequently, decreased polyfunctional CD8+CD107a+IFNɣ+IL2-TNFα- cells (first visit 0.43% vs second visit 0.10%, p=0.81).

Conclusion

Polyfunctional CD8+ EBV-specific T-cell response allows detecting EBV previous contact in liver-transplant children. %CD8+CD107a+IFNɣ+IL2-TNFα- is increased in patients with positive viral loads. Central memory CD4+ T-cell population more effectively determines prior EBV-exposure in adults.

Impacts of Medications on Microbiome-mediated Protection against Enteric Pathogens

The majority of people in the U.S. manage health through at least one prescription drug. Drugs classified as non-antibiotics can adversely affect the gut microbiome and disrupt intestinal homeostasis. Here, we identified medications associated with an increased risk of GI infections across a population cohort of more than 1 million individuals monitored over 15 years. Notably, the cardiac glycoside digoxin and other drugs identified in this epidemiological study are sufficient to alter microbiome composition and risk of Salmonella enterica subsp. Typhimurium (S. Tm) infection in mice. The impact of digoxin treatment on S. Tm infection is transmissible via the microbiome, and characterization of this interaction highlights a digoxin-responsive β-defensin that alters microbiome composition and consequent immune surveillance of the invading pathogen. Combining epidemiological and experimental approaches thus provides an opportunity to uncover drug-host-microbiome-pathogen interactions that increase infection risk in humans.

Clinical Features, Diagnostics, Etiology, and Outcomes of Hospitalized Solid Organ Recipients With Community-Acquired Pneumonia: A Retrospective Cohort Analysis

BACKGROUND

Community-acquired pneumonia (CAP) is a leading cause of morbidity and mortality worldwide. Limited evidence is available on the most effective diagnostic approaches, management strategies, and long-term outcomes for CAP in patients who have undergone solid organ transplantation.

RESEARCH QUESTION

What is the acute and long-term morbidity and mortality after CAP in organ transplant recipients?

STUDY DESIGN AND METHODS

We retrospectively analyzed hospitalizations for CAP in solid organ recipients at the largest German transplant center. The study included patients admitted between January 1, 2010, and May 31, 2021. The reported outcomes are in-hospital and 1-year mortality, risk of cardiovascular events during hospitalization and at 1 year, admission to the ICU, and risk of pneumonia with Pseudomonas aeruginosa. Multivariable binary logistic regression using stepwise forward selection was performed to determine predictive factors for pneumonia with P aeruginosa.

RESULTS

We analyzed data from 403 hospitalizations of 333 solid organ recipients. In > 60% of cases, patients had multiple comorbidities, with cardiovascular and chronic kidney disease being the most prevalent. More than one-half of the patients required oxygen supplementation after admission. In-hospital mortality (13.2%) and the death rate at 1 year postevent (24.6%) were higher than data reported from immunocompetent patients. We also observed high rates of acute cardiovascular events and events occurring 1 year after admission. Early blood cultures and bronchoscopy in the first 24 h significantly increased the odds of establishing an etiology. In our low-resistance setting, the burden of antimicrobial resistance was driven by bacteria from chronically colonized patients, mostly lung transplant recipients.

INTERPRETATION

This comprehensive analysis highlights the high morbidity associated with CAP after transplantation. It also emphasizes the need for prospective multicenter studies to guide evidence-based practices and improve outcomes for these vulnerable patients.

Polysaccharides of Floccularia luteovirens regulate intestinal immune response, and oxidative stress activity through MAPK/Nrf2/Keap1 signaling pathway in immunosuppressive mice

This study explores the novel immunomodulatory effects of polysaccharides from the rare Floccularia luteovirens, a fungus with significant potential yet unexplored bioactive components, traditionally used in Tibetan medicine. This study employs a wide array of analytical techniques, including HPGPC, HPLC, western blotting, ELISA, and 16S rRNA gene sequencing, to comprehensively investigate FLP1's effects. The main structure of FLP1 was characterized by IF-TR and NMR spectrometry. The structural backbone of FLP1 was →3,6)-β-D-Glcp-(1 → and →2,3)-α-D-Manp-(1→. After immunosuppressed mice treated with FLP1, the findings demonstrated that FLP1 stimulated the production of secretory sIgA and secretion of cytokines (IL-4, TNF-α, and IFN-γ) in the intestine of Cy-treated mice, resulting in the activation of the MAPK pathway. Additionally, FLP1 protected oxidative stress by triggering Nrf2/Keap1 pathways and antioxidation enzymes (SOD, MDA, T-AOC, CAT, and GSH-Px). It also enhanced the intestinal barrier function by regulating the villous height ratio and expression of tight-junction protein. Furthermore, FLP1 remarkably reversed the gut microbiota dysbiosis in immunosuppressed mice by increasing the abundance of Oscilliospiraceae, and Lachnospiraceae, and altered the fecal metabolites by increasing LysoPE (0:0/18:0); 0:0/16:0; 18:1(11Z)/0:0, LysoPG (16:0/0:0), LysoPG 18:1 (2n) PE (14:0/20:1), echinenone, 2-(2-Nitroimidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl) acetamide, and suberic acid which is closely related to the immunity function. These results suggested that FLP1 may regulate the intestinal immune response by modulating the gut microbiota and fecal metabolites in immunosuppressed mice thereby activating the immune system.

Immune response against bacterial infection in organ transplant recipients

This comprehensive review delves into the intricate dynamics between the immune system and bacterial infections in organ transplant recipients. Its primary objective is to fill existing knowledge gaps while critically assessing the strengths and weaknesses of current research. The paper accentuates the delicate balance that must be struck between preventing graft rejection through immunosuppression and maintaining robust immunity against bacterial threats. In this context, personalized medicine emerges as a transformative concept, offering the potential to revolutionize clinical outcomes by tailoring immunosuppressive regimens and vaccination strategies to the unique profiles of transplant recipients. By emphasizing the pivotal role of continuous monitoring, the review underscores the necessity for vigilant surveillance of transplant recipients to detect bacterial infections and associated immune responses early, thereby reducing the risk of severe infections and ultimately improving patient outcomes. Furthermore, the study highlights the significance of the host microbiome in shaping immune responses, suggesting that interventions targeting the microbiome hold promise for enhancing bacterial immunity in transplant recipients, both in research and clinical practice. In terms of future research directions, the review advocates for large-scale, longitudinal studies encompassing diverse patient cohorts to provide more comprehensive insights into post-transplant immune responses. It also advocates integrating multi-omics approaches, including genomics, transcriptomics, proteomics, and microbiome data, to understand immune responses and their underlying mechanisms. In conclusion, this review significantly enriches our understanding of immune responses in transplant recipients. It paves the way for more effective and personalized approaches to managing infections in this complex setting.

Evolving trends in immunosuppression use and cytomegalovirus infection risk over the past decade in kidney transplantation

BACKGROUND

The goal was to determine trends in immunosuppression use and its impact on cytomegalovirus (CMV) outcomes over the past 10 years.

METHODS

This was a single-center longitudinal cohort study of adult kidney recipients transplanted between Jan 2012 and June 2021. Baseline and follow-up data were gathered via chart abstraction and analyzed using univariate and multivariate analyses.

RESULTS

Of 2392 kidney transplants conducted, 131 patients did not meet inclusion criteria. The mean age was 52 years, 41% were female, 57% were black, and 19% were CMV high-risk. The use of rabbit anti-thymocyte globulin (RATG) induction (odds ratio [OR] 1.6, 1.3-2.1), tacrolimus (FK) level >8 ng/mL (OR 1.1, 1.09-1.11), CMV D+/R- rates (OR 1.06, 1.02-1.10), white blood cell count <3000 (OR 1.22, 1.18-1.26) and valganciclovir prophylaxis (OR 1.7, 1.6-1.9) have significantly increased over the past 10 years.  Rejection rates (OR 0.86, 0.82-0.91) and BK viremia >2000 (OR 0.91, 0.91-0.98) have decreased. RATG induction (adjusted hazard ratio [aHR] 1.35, 1.2-1.5), FK >8 ng/mL (aHR 3.5, 3.2-3.9), Belatacept conversion (aHR 2.5, 2.1-3.1), and rejection (aHR 1.8, 1.6-2.0) were significant risk factors for developing CMV infection, while mycophenolate mofetil <1500 mg (aHR 0.52, 0.47-0.59), mammalian target of rapamycin inhibitor (mTORi) conversion (0.77, 0.56-0.89), cyclosporine-A conversion (aHR 0.68, 0.56-0.84) were associated with lower risk of CMV infection.

CONCLUSION

Increasing use of potent immunosuppression coupled with higher CMV D+/R- F rates may be driving higher rates of CMV infection. Cyclosporine and mTORi conversion appears to be protective against CMV.  A more individualized immunosuppression regimen based on infection risk merits consideration.

Influence of dental status on postoperative complications in major visceral surgical and organ transplantation procedures-the bellydent retrospective observational study

PURPOSE

The significance of dental status and oral hygiene on a range of medical conditions is well-recognised. However, the correlation between periodontitis, oral bacterial dysbiosis and visceral surgical outcomes is less well established. To this end, we study sought to determine the influence of dental health and oral hygiene on the rates of postoperative complications following major visceral and transplant surgery in an exploratory, single-center, retrospective, non-interventional study.

METHODS

Our retrospective non-interventional study was conducted at the Department of General, Visceral, and Transplant Surgery, University Hospital Heidelberg, Germany. Patients operated on between January 2018 and December 2019 were retrospectively enrolled in the study based on inclusion (minimum age of 18 years, surgery at our Department, intensive care / IMC treatment after major surgery, availability of patient-specific preoperative dental status assessment, documentation of postoperative complications) and exclusion criteria (minor patients or legally incapacitated patients, lack of intensive care or intermediate care (IMC) monitoring, incomplete documentation of preoperative dental status, intestinal surgery with potential intraoperative contamination of the site by intestinal microbes, pre-existing preoperative infection, absence of data regarding the primary endpoints of the study). The primary study endpoint was the incidence of postoperative complications. Secondary study endpoints were: 30-day mortality, length of hospital stay, duration of intensive care stay, Incidence of infectious complications, the microbial spectrum of infectious complication. A bacteriology examination was added whenever possible (if and only if the examination was safe for the patient)for infectious complications.

RESULTS

The final patient cohort consisted of 417 patients. While dental status did not show an influence (p = 0.73) on postoperative complications, BMI (p = 0.035), age (p = 0.049) and quick (p = 0.033) were shown to be significant prognostic factors. There was significant association between oral health and the rate of infectious complications for all surgical procedures (p = 0.034), excluding transplant surgery. However, this did not result in increased 30-day mortality rates, prolonged intensive care unit treatment or an increase in the length of hospital stay (LOS) for the cohort as a whole. In contrast there was a significant correlation between the presence of oral pathogens and postoperative complications for a group as a whole (p < 0.001) and the visceral surgery subgroup (p < 0.001). Whilst this was not the case in the cohort who underwent transplant surgery, there was a correlation between oral health and LOS in this subgroup (p = 0.040). Bacterial swabs supports the link between poor oral health and infectious morbidity.

CONCLUSIONS

Dental status was a significant predictor of postoperative infectious complications in this visceral surgery cohort. This study highlights the importance preoperative dental assessment and treatment prior to major surgery, particularly in the case of elective surgical procedures. Further research is required to determine the effect of oral health on surgical outcomes in order to inform future practice.

TRIAL REGISTRATION

Trial registered under the ethics-number S-082/2022 (Ethic Committee of the University Heidelberg).

Mechanistic Understanding of EBV+Lymphoproliferative Disease Development After Transplantation

Posttransplant lymphoproliferative disorders (PTLDs) are among the most common malignant complications after transplantation, leading to a drastic reduction in patient survival rates. The majority of PTLDs are tightly linked to Epstein-Barr virus (EBV+PTLDs) and are the result of an uncontrolled proliferation of EBV-infected cells. However, although EBV infections are a common finding in transplant recipients, most patients with high EBV loads will never develop EBV+PTLD. Natural killer cells and EBV-specific CD8+ T lymphocytes are critical for controlling EBV-infected cells, and the impairment of these cytotoxic immune responses facilitates the unfettered proliferation of EBV-infected cells. Recent years have seen a considerable increase in available literature aiming to describe novel risk factors associated with the development of EBV+PTLD, which may critically relate to the strength of EBV-specific natural killer cell and EBV-CD8+ T lymphocyte responses. The accumulation of risk factors and the increased risk of developing EBV+PTLD go hand in hand. On the one hand, most of these risk factors, such as the level of immunosuppression or the EBV donor and recipient serologic mismatch, and distinct genetic risk factors are host related and affect cytotoxic EBV-specific immune responses. On the other hand, there is growing evidence that distinct EBV variants may have an increased malignant potential and are thus more likely to induce EBV+PTLD. Here, we aim to review, from a mechanistic point of view, the risk factors for EBV+PTLD in the host and the infecting EBV variants that may explain why only a minority of transplant recipients develop EBV+PTLD.

pO2 reporter composite hydrogel macroencapsulation devices for magnetic resonance imaging oxygen quantification

Hydrogel cell encapsulation devices are a common approach to reduce the need for chronic systemic immunosuppression in allogeneic cell product transplantation. Macroencapsulation approaches are an appealing strategy, as they maximize graft retrievability and cell dosage within a single device; however, macroencapsulation devices face oxygen transport challenges as geometries increase from preclinical to clinical scales. Device design guided by computational approaches can facilitate graft oxygen availability to encapsulated cells in vivo but is limited without accurate measurement of oxygen levels within the transplant site and graft. In this study, we engineer pO2 reporter composite hydrogels (PORCH) to enable spatiotemporal measurement of oxygen tension within macroencapsulation devices using the proton Imaging of siloxanes to map tissue oxygenation levels (PISTOL) magnetic resonance imaging approach. We engineer two methods of incorporating siloxane oximetry reporters within hydrogel devices, an emulsion and microbead-based approach, and evaluate PORCH cytotoxicity on co-encapsulated cells and accuracy in quantifying oxygen tension in vitro. We find that both emulsion and microbead PORCH approaches enable accurate in situ oxygen quantification using PISTOL magnetic resonance oximetry, and that the emulsion-based PORCH approach results in higher spatial resolution.

Pharmacomicrobiomics: Immunosuppressive Drugs and Microbiome Interactions in Transplantation

The human microbiome is associated with human health and disease. Exogenous compounds, including pharmaceutical products, are also known to be affected by the microbiome, and this discovery has led to the field of pharmacomicobiomics. The microbiome can also alter drug pharmacokinetics and pharmacodynamics, possibly resulting in side effects, toxicities, and unanticipated disease response. Microbiome-mediated effects are referred to as drug-microbiome interactions (DMI). Rapid advances in the field of pharmacomicrobiomics have been driven by the availability of efficient bacterial genome sequencing methods and new computational and bioinformatics tools. The success of fecal microbiota transplantation for recurrent Clostridioides difficile has fueled enthusiasm and research in the field. This review focuses on the pharmacomicrobiome in transplantation. Alterations in the microbiome in transplant recipients are well documented, largely because of prophylactic antibiotic use, and the potential for DMI is high. There is evidence that the gut microbiome may alter the pharmacokinetic disposition of tacrolimus and result in microbiome-specific tacrolimus metabolites. The gut microbiome also impacts the enterohepatic recirculation of mycophenolate, resulting in substantial changes in pharmacokinetic disposition and systemic exposure. The mechanisms of these DMI and the specific bacteria or communities of bacteria are under investigation. There are little or no human DMI data for cyclosporine A, corticosteroids, and sirolimus. The available evidence in transplantation is limited and driven by small studies of heterogeneous designs. Larger clinical studies are needed, but the potential for future clinical application of the pharmacomicrobiome in avoiding poor outcomes is high.

Structural properties of glucan from Russula griseocarnosa and its immunomodulatory activities mediated via T cell differentiation

The polysaccharide, RGP2, was isolated from Russula griseocarnosa and its immunostimulatory effects were confirmed in cyclophosphamide (CTX)-induced immunosuppressed mice. Following purification via chromatography, structural analysis revealed that RGP2 had a molecular weight of 11.82 kDa and consisted of glucose (Glc), galactose (Gal), mannose, glucuronic acid and glucosamine. Bond structure analysis and nuclear magnetic resonance characterization confirmed that the main chain of RGP2 was formed by →6)-β-D-Glcp-(1→, →3)-β-D-Glcp-(1→ and →6)-α-D-Galp-(1→, which was substituted at O-3 of →6)-β-D-Glcp-(1→ by β-D-Glcp-(1→. RGP2 was found to ameliorate pathological damage in the spleen and enhance immune cell activity in immunosuppressed mice. Based on combined multiomics analysis, RGP2 altered the abundance of immune-related microbiota (such as Lactobacillus, Faecalibacterium, and Bacteroides) in the gut and metabolites (uridine, leucine, and tryptophan) in the serum. Compared with immunosuppressed mice, RGP2 also restored the function of antigen-presenting cells, promoted the polarization of macrophages into the M1 phenotype, positively affected the differentiation of helper T cells, and inhibited regulatory T cell differentiation through the protein kinase B (AKT)/mechanistic target of rapamycin (mTOR) pathway, ultimately exerting an immune boosting function. Overall, our findings highlight therapeutic strategies to alleviate CTX-induced immunosuppression in a clinical setting.

Posttransplant complications: molecular mechanisms and therapeutic interventions

Posttransplantation complications pose a major challenge to the long-term survival and quality of life of organ transplant recipients. These complications encompass immune-mediated complications, infectious complications, metabolic complications, and malignancies, with each type influenced by various risk factors and pathological mechanisms. The molecular mechanisms underlying posttransplantation complications involve a complex interplay of immunological, metabolic, and oncogenic processes, including innate and adaptive immune activation, immunosuppressant side effects, and viral reactivation. Here, we provide a comprehensive overview of the clinical features, risk factors, and molecular mechanisms of major posttransplantation complications. We systematically summarize the current understanding of the immunological basis of allograft rejection and graft-versus-host disease, the metabolic dysregulation associated with immunosuppressive agents, and the role of oncogenic viruses in posttransplantation malignancies. Furthermore, we discuss potential prevention and intervention strategies based on these mechanistic insights, highlighting the importance of optimizing immunosuppressive regimens, enhancing infection prophylaxis, and implementing targeted therapies. We also emphasize the need for future research to develop individualized complication control strategies under the guidance of precision medicine, ultimately improving the prognosis and quality of life of transplant recipients.

Alloreactive memory CD4 T cells promote transplant rejection by engaging DCs to induce innate inflammation and CD8 T cell priming

Alloreactive memory T cells have been implicated as central drivers of transplant rejection. Perplexingly, innate cytokines, such as IL-6, IL-1β, and IL-12, are also associated with rejection of organ transplants. However, the pathways of innate immune activation in allogeneic transplantation are unclear. While the role of microbial and cell death products has been previously described, we identified alloreactive memory CD4 T cells as the primary triggers of innate inflammation. Memory CD4 T cells engaged MHC II-mismatched dendritic cells (DCs), leading to the production of innate inflammatory cytokines. This innate inflammation was independent of several pattern recognition receptors and was primarily driven by TNF superfamily ligands expressed by alloreactive memory CD4 T cells. Blocking of CD40L and TNFα resulted in dampened inflammation, and mice genetically deficient in these molecules exhibited prolonged survival of cardiac allografts. Furthermore, myeloid cell and CD8 T cell infiltration into cardiac transplants was compromised in both CD40L- and TNFα-deficient recipients. Strikingly, we found that priming of naive alloreactive CD8 T cells was dependent on licensing of DCs by memory CD4 T cells. This study unravels the key mechanisms by which alloreactive memory CD4 T cells contribute to destructive pathology and transplant rejection.

Nanotechnology-based Strategies for Molecular Imaging, Diagnosis, and Therapy of Organ Transplantation

Organ transplantation is the preferred paradigm for patients with end-stage organ failures. Despite unprecedented successes, complications such as immune rejection, ischemia-reperfusion injury, and graft dysfunction remain significant barriers to long-term recipient survival after transplantation. Conventional immunosuppressive drugs have limited efficacy because of significant drug toxicities, high systemic immune burden, and emergence of transplant infectious disease, leading to poor quality of life for patients. Nanoparticle-based drug delivery has emerged as a promising medical technology and offers several advantages by enhancing the delivery of drug payloads to their target sites, reducing systemic toxicity, and facilitating patient compliance over free drug administration. In addition, nanotechnology-based imaging approaches provide exciting diagnostic methods for monitoring molecular and cellular changes in transplanted organs, visualizing immune responses, and assessing the severity of rejection. These noninvasive technologies are expected to help enhance the posttransplantation patient survival through real time and early diagnosis of disease progression. Here, we present a comprehensive review of nanotechnology-assisted strategies in various aspects of organ transplantation, including organ protection before transplantation, mitigation of ischemia-reperfusion injury, counteraction of immune rejection, early detection of organ dysfunction posttransplantation, and molecular imaging and diagnosis of immune rejection.

Pulmonary Nocardiosis in Renal Transplant Recipients From Pakistan: Risk Factors, Clinical Presentation, and Mortality

OBJECTIVES

Nocardia is an opportunistic infection among renal transplant recipients with an incidence of <1% but high mortality. Data from Pakistan are scarce. Our aim was to find the risk factors, clinical and radiographic findings, antimicrobial sensitivity, and outcomes of Nocardia infection among renal transplant recipients in Pakistan.

MATERIALS AND METHODS

All adult renal transplant recipients diagnosed with nocardiosis between 2013 and 2020 were included. The cases were matched 1:2 with controls based on sex, age (±1 year), and transplant date (±1 year). Risk factors, clinical features, antibiotic sensitivities and outcomes were analyzed.

RESULTS

A total of 48 patients developed nocardiosis. Around 25% of patients presented with disseminated disease. Median time from transplant to disease development was 2.68 years. High-dose methylprednisolone and presence of cytomegalovirus infection within 90 days of disease development were independent risk factors for Nocardia infection. The mortality rate was 20%. Central nervous system disease and cytomegalovirus infection within 90 days were significantly associated with mortality. The most susceptible drugs were co-trimoxazole and linezolid. Imipenem susceptibility was only 20%.

CONCLUSIONS

High-dose methylprednisolone and cytomegalovirus infection were independent risk factors for Nocardia infection. Central nervous system disease was associated with mortality. Nocardia species were highly resistant to ceftriaxone and imipenem in our patient population.

Management of Immunosuppressive Therapy in Kidney Transplant Recipients with Sepsis: A Multicenter Retrospective Study

BACKGROUND

Up to 6% of kidney transplant recipients (KTRs) experience life-threatening complications requiring intensive care unit (ICU) admission, and one of the most common medical complications requiring ICU admission is infection. This study aimed to evaluate the effect of immunosuppressive therapy (IST) modification on prognosis of KTRs with sepsis.

METHODS

We conducted a multicenter retrospective study in 4 university-affiliated hospitals to evaluate the effect of adjusting the IST in KTRs with sepsis. Only patients who either maintained IST after ICU admission or those who underwent immediate (within 24 h of ICU admission) reduction or withdrawal of IST following ICU admission were included in this study. "Any reduction" was defined as a dosage reduction of any IST or discontinuation of at least 1 IST. "Complete withdrawal of IST" was defined as concomitant discontinuation of all ISTs, except steroids.

RESULTS

During the study period, 1596 of the KTRs were admitted to the ICU, and 112 episodes of sepsis or septic shock were identified. The overall in-hospital mortality rate was 35.7%. In-hospital mortality was associated with higher sequential organ failure assessment score, simplified acute physiology score 3, non-identical human leukocyte antigen relation, presence of septic shock, and complete withdrawal of IST. After adjusting for potential confounding factors, complete withdrawal of IST remained significantly associated with in-hospital mortality (adjusted coefficient, 1.029; 95% confidence interval, 0.024-2.035) and graft failure (adjusted coefficient, 2.001; 95% confidence interval, 0.961-3.058).

CONCLUSIONS

Complete IST withdrawal was common and associated with worse outcomes in critically ill KTRs with sepsis.