Allograft rejection following immune checkpoint inhibitors in solid organ transplant recipients: A safety analysis from a literature review and a pharmacovigilance system

Impact of exosomes derived from adipose stem cells on lymphocyte proliferation and phenotype in mouse skin grafts

Aim: Exosomes derived from adipose-derived stem cells (ASCs) in mice have been reported to influence immune regulation. Yet, the potential immunological effects of ASCs-derived exosomes and their interaction with lymphocytes during transplant immunity remain understudied. Methods: ASCs from BALB/c mice, along with their conditioned culture medium, were collected for the extraction, isolation, and comprehensive characterization of exosomes. Splenic cell suspensions were isolated from BALB/c mice and subsequently processed for downstream analyses. Lymphocytes were isolated via gradient centrifugation and stimulated in vitro with the purified exosomes to assess their functional responses. Lymphocyte proliferation was quantified using the CCK8 assay, and the relative frequencies of CD4+ T cells, CD8+ T cells, Treg cells, NK (natural killer) cells, macrophages, B cells, dendritic cells (DCs), and Th17 cells were determined through flow cytometric analysis. Before establishing the skin transplantation model, the mice were administered PBS, 0.5 × 108 exosomes, 1 × 108 exosomes, 1.5 × 108 exosomes, or ASCs via intravenous injection through the tail vein. Seven days after transplantation, the spleens, drainage lymph nodes, and blood samples were harvested for lymphocyte isolation and further downstream analyses. Results: Exosomes derived from ASCs significantly increased the CD4+/CD8+ ratio and Treg cell levels, without inducing any notable changes in Th17 cell content or CTLA-4 protein expression in CD4+ T cells. Compared to the PBS-treated group, both ASC and exosome treatment groups demonstrated an enhanced CD4+/CD8+ ratio, increased Treg cell content, and elevated CTLA-4 protein expression in spleen tissue following skin transplantation, while Th17 cell levels remained unaffected. Compared to the ASC treatment group, the exosome group exhibited a higher CD4+/CD8+ ratio and Treg cell levels, alongside a reduced proportion of PD-1+ Treg cells and lower CTLA-4 protein expression in CD3+CD4+ T cells. No significant differences were observed in the proportions of NK cells, macrophages, B cells, and DCs in the spleens across all treatment groups. In peripheral blood, an increased proportion of CD3+ T cells, macrophages, and DCs was detected, accompanied by a reduced proportion of NK cells and B cells. In the draining lymph nodes, no significant changes were observed in the proportions of CD3+ T cells and B cells, while macrophages, NK cells, and DCs showed elevated proportions. In the exosome-treated group, mouse grafts exhibited a disorganized and thinner granular layer, accompanied by focal regions of inflammatory cell infiltration. Both exosome and ASC treatments significantly extended the survival of skin grafts. Conclusion: Exosomes derived from ASCs promote lymphocyte proliferation and modulate their phenotypic profiles in mouse skin graft models, effectively extending graft survival.

Modern Approach to Manage Patients With Kaposi Sarcoma

Kaposi sarcoma (KS) is a malignancy associated with Kaposi's sarcoma-associated herpesvirus (KSHV), primarily affecting immunocompromised individuals, such as those with HIV or those receiving immunosuppressive treatments. Immunocompetent individuals may also be affected, illustrating the disease's heterogeneity. KS manifests in different forms-classic, endemic, epidemic, iatrogenic, and in men having sex with men-each with distinct clinical features depending on immune status and geographic area of origin. Although advances in treatment have improved disease control, effective management remains a challenge. This review focuses on the comprehensive approach to investigating and treating KS. It highlights the role of histology, immunohistochemistry, and staging in diagnosing KS and assessing disease extension, together with other KSHV diseases (multicentric Castelman disease, primary effusion lymphoma, and KS inflammatory cytokine syndrome). Treatment strategies are discussed, with emphasis on restoring immunity in immunocompromised patients, alongside conventional local therapies, and chemotherapy options like liposomal doxorubicin and paclitaxel for aggressive and extensive forms. Promising emerging therapies, including immunomodulatory agents, antiangiogenic therapies, and checkpoint inhibitors, are also explored. The review emphasizes the importance of personalized treatment based on the patient's underlying condition and KS subtype. It provides an in-depth look at the pathogenesis, diagnostic methods, and evolving therapeutic approaches, offering valuable insights into improving management and outcomes for KS patients.

Dental implants in solid organ transplant recipients: A systematic review and meta-analysis

PURPOSE

It remains to be determined whether dental implantation treatment in solid organ transplant (SOT) recipients and non-organ transplant patients yields similar clinical outcomes. This review summarizes related data for existing cases and presents a meta-analysis of the outcomes of dental implants in SOT recipients and non-organ transplant patients.

MATERIAL AND METHODS

An electronic literature search was conducted in the PubMed, Web of Sciences, Cochrane Library and China National Knowledge Infrastructure databases covering articles published from inception to December 2024. This study was performed in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines and was designed based on the Population, Intervention, Comparison, Outcome and Study design (PICOS) framework. The risk of bias was evaluated using the Joanna Briggs Institute (JBI) Critical Appraisal Checklist or the Newcastle-Ottawa Scale (NOS). The certainty of findings was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria. Meta-analysis was performed using a fixed effects model to estimate the combined performance measures and 95% confidence intervals for the implant survival rate, marginal bone loss (MBL), and probing depth (PD).

RESULTS

A total of 12 articles were included in the systematic review. The implant survival rate of 290 implants in 110 SOT recipients was 99.3%. The meta-analysis of four case-control studies revealed no significant differences in the implant survival rate and PD between SOT recipients and non-organ transplant patients (P=0.45 and P=0.49, respectively), while there was slightly less MBL in SOT recipients (P=0.02), possibly caused by confounding factors and bias.

CONCLUSIONS

Organ transplantation does not impair implant survival in the short and mid-long term. Dental implantation can serve as a treatment option for tooth loss in SOT recipients.

Successful use of therapeutic plasma exchange for the management of acute lung transplant rejection secondary to immune checkpoint inhibitor therapy

The use of immune checkpoint inhibitors (ICIs) in individuals with a history of solid organ transplantation is fraught with the emergence of solid organ transplantation rejection (SOTR). The current recommendations for the management of SOTRs secondary to ICI include the use of high-dose steroids along with the escalation of immunosuppressive therapy. Therapeutic Plasma Exchange (TPE) has been described to be effective in managing various immune-related toxicities, however, the data for using TPE in the setting of acute SOTRs induced by ICIs are limited. Herein, we describe the successful use of TPE in a patient with a history of bilateral lung transplantation who developed an episode of mixed acute cellular and antibody-mediated lung transplant rejection after a single dose of PD-1 inhibitor Pembrolizumab for the treatment of underlying melanoma.

Elevated PD-L1 and PECAM-1 as Diagnostic Biomarkers of Acute Rejection in Lung Transplantation

Acute cellular rejection (ACR) frequently occurs following lung transplantation (LuTx) and represents a risk factor for the development of chronic lung allograft dysfunction (CLAD) as well as long-term survival. The histopathological diagnosis of ACR carries a burden of interobserver variability. The widespread utilization and cost-effectiveness of immunohistochemistry (IHC) was proven beneficial in diagnosing rejection in human kidney transplantations and LuTx rat models. However, its potential for ACR detection in patients remains unexplored. We analyzed surface markers (CD3, CD4, CD8, CD20, CD68, CD47, PD-1, PD-L1, and CD31/PECAM-1) on lung tissue cryobiopsy samples collected within 6 months post-LuTx from 60 LuTx recipients, 48 of whom were diagnosed with ACR. Additionally, serum samples from 51 patients were analyzed using a multiplex bead-based Luminex assay. The cytokines and markers included PD-L1, IL2, TNFα, IFNγ, and Granzyme B. We observed a significant increase in PD-L1 tissue expression within the rejection group, suggesting a concerted effort to suppress immune responses, especially those mediated by T-cells. Furthermore, we noted significant differences in PECAM-1 levels between ACR/non-ACR. Additionally, peripheral blood C-reactive-protein levels tended to be higher in the ACR group, while Luminex serum analyses did not reveal any significant differences between groups. In conclusion, our findings suggest the potential value of PECAM-1 and PD-L1 markers in diagnosing ACR.

Unforeseen Complications of Pembrolizumab in Breast Reconstruction Post-Mastectomy

A 53-year-old post-menopausal Indian female presented with invasive ductal carcinoma, treated with neoadjuvant chemotherapy and pembrolizumab due to a PD-L1 combined positive score of 5. Following a right mastectomy and axillary dissection, she received a breast expander and AlloDerm™ graft. After resuming pembrolizumab and paclitaxel postoperatively, she developed severe breast redness and high-grade fever, necessitating expander removal due to suspected pembrolizumab-induced complications. This case underscores the unique and severe adverse effects of pembrolizumab on breast reconstruction, highlighting the need for careful monitoring and management in patients undergoing similar treatments.

LEARNING POINTS

Among patients with early triple-negative breast cancer, the combination of pembrolizumab with neoadjuvant chemotherapy enhances outcomes compared to chemotherapy alone.Early recognition is essential for managing pembrolizumab-induced complications, as demonstrated by the need for expander removal and debridement in this case.The unique adverse effects observed in this case underscore the importance of tailoring cancer treatment plans to individual patients, taking into account the potential risks associated with immunotherapy in the context of reconstructive surgery.

Fine-tuning tumor- and allo-immunity: advances in the use of immune checkpoint inhibitors in kidney transplant recipients

Cancer is a common complication after kidney transplantation. Kidney transplant recipients (KTR) have a 2- to 4-fold higher risk of developing cancer compared to the general population and post-transplant malignancy is the third most common cause of death in KTR. Moreover, it is well known that certain cancer types are overrepresented after transplantation, especially non-melanoma skin cancer. Immune checkpoint inhibitors (ICI) have revolutionized the treatment of cancer, with remarkable survival benefit in a subgroup of patients. ICI are monoclonal antibodies that block the binding of specific co-inhibitory signaling molecules. Cytotoxic T lymphocyte-associated antigen-4 (CTLA-4), programmed cell death protein 1 (PD-1), and its ligand programmed cell death ligand 1 (PD-L1) are the main targets of ICI. Solid organ transplant recipients (SOTR) have been excluded from clinical trials owing to concerns about tumor response, allo-immunity, and risk of transplant rejection. Indeed, graft rejection has been estimated as high as 48% and represents an emerging problem. The underlying mechanisms of organ rejection in the context of treatment with ICI are poorly understood. The search for restricted antitumoral responses without graft rejection is of paramount importance. This review summarizes the current knowledge of the use of ICI in KTR, the potential mechanisms involved in kidney graft rejection during ICI treatment, potential biomarkers of rejection, and how to deal with rejection in clinical practice.

Metastatic Melanoma Treatment in Special Populations

ABSTRACT

This review outlines the most up-to-date metastatic melanoma treatment recommendations and relevant risks for patients with solid organ transplants, patients with renal dysfunction, and patients with preexisting autoimmune conditions. These specific treatment populations were excluded from the original clinical trials, which studied immune checkpoint inhibitors and BRAF/MEK inhibitors in the advanced melanoma setting. We have synthesized the current body of literature, mainly case series and retrospective analyses, to reflect the evidence for the treatment of these special patient populations at present.

Current Trends and Future Directions of Malignancy After kidney Transplantation: A 1970-2022 Bibliometric Analysis

BACKGROUND Malignancy after kidney transplantation (MKT) remains a leading cause of death in transplant recipients and over the past few decades there have been many reports on this topic. However, the task of extracting crucial information from intricate events poses a significant challenge in guiding clinical work. Hence, bibliometrics was employed to summarize and predict the future in this study. MATERIAL AND METHODS Reviews and articles on MKT were extracted from the Web of Science Core Collection (WoSCC) and were analyzed by the software VOSviewer, CiteSpace, Scimago Graphica, and R package Bibliometrix for bibliometric analysis. RESULTS The analysis considered 5700 publications from 28 647 authors and 4924 institutions across 100 countries, spanning the years 1970-2022. Reference co-citation analysis showed that "renal cell carcinoma", "skin cancer", "post-transplant lymphoproliferative disorder" and "COVID-19 vaccine" were research hotspots. Keywords that co-occurred early were "immunosuppressant", "cancer", "Epstein-Barr virus", "squamous cell carcinoma", and "infection", etc., while "impact","risk factor", "outcomes", "mortality", "management" frequently co-occurred later. From 2020 to 2022, newly emerging keywords such as "SARS-CoV-2" and "COVID-19", together with citation bursts for "immune checkpoint inhibitors" and "ipilimumab," were observed. CONCLUSIONS The focus of MKT-related studies has evolved from exploring the spectrum, risk factors, and outcomes of MKT, to examining the pathogenesis, individualized screening, prevention, and treatment, including appropriate use of immune checkpoint inhibitors. Reports of renal transplant recipients infected with SARS-CoV-2 or COVID-19 have also gained attention since 2019. These suggest that individualized management remains a frontier for research and a future direction in MKT topics.