Transplant immunology最新文献

Introduction

A better understanding of the immune mechanisms involved in allograft rejection after transplantation is urgently needed to improve patient outcomes. As microRNA-155 (miR155) plays a critical role in inflammation, we postulated that a deficiency of miR155 will improve cardiac allograft survival and enhance tolerance induction after heart transplantation.

Methods

We developed an acute rejection mouse model through heterotopic BALB/c cardiac transplantation to C57BL/6 (wild-type) and C57BL/6 miR155 knock-out (miR155KO) mice. Further, we induced tolerance in both groups through a costimulatory blockade with CTLA4-Ig (200 μg; post-transplant day 2) and MRI antibodies (250 μg; post-transplant day 0), targeting CD28/B7 and CD40/CD154 signals, respectively. Finally, we examined the effects of injecting 100 μg of small extracellular vesicles (sEVs) isolated from wild-type mice undergoing rejection into tolerant miR155KO mice.

Results

Mean survival time (MST) of the cardiac allografts in wild-type and miR155KO mice was 7 and 15 days, respectively (p < 0.0001). Costimulatory blockade increased MST to 65 days and > 100 days in the wild-type and miR155KO recipients, respectively (p < 0.001). Injection of sEVs isolated from wild-type mice undergoing rejection into tolerant miR155KO mice decreased the allograft survival to 9 days, significantly lower than the tolerant miR155KO mice without injection of sEVs (>100 days; p < 0.0001).

Conclusion

miR155KO mice have improved cardiac allograft survival and enhanced induction of tolerance after heterotopic cardiac transplantation. Injection of sEVs from wild-type mice undergoing rejection into the miR155KO mice reversed these benefits.

Background

The potential of Tocilizumab (TCZ) in preventing the cytokine storm caused by COVID-19 infection has been observed, while the survival benefits were inconclusive in solid-organ transplant recipients. We aimed to explore whether the timing of TCZ administration holds significance in the clinical course of COVID-19 infection and identify predicative factors of TCZ efficacy.

Methods

We conducted a prospective cohort study between December 2022, and January 2023. Early TCZ use referred to administration within 6 days after symptoms onset, while late TCZ use indicated administration after 6 days. The primary endpoint was 30-day mortality.

Results

Twenty-seven kidney transplant recipients with severe COVID-19 infection were enrolled, with 10 in the early use group and 17 in the late use group. In the early use group, ferritin, lactate dehydrogenase (LDH), C-reactive protein (CRP) and brain natriuretic peptide(BNP) levels had shown significant inhibitions comparing to the late use group, and those inflammatory cytokines demonstrated a noticeable decreasing trend after TCZ administration, whereas only CRP levels decreased in the late use group. The Kaplan-Meier survival curve demonstrated that the early use group had a higher likelihood of survival (P = 0.0078). Receiver Operating Characteristic (ROC) analyses revealed that the time from symptoms to TCZ use (AUC: 0.645), LDH (AUC: 0.803), CRP (AUC: 0.787), and IL-6 (AUC: 0.725) were potential predictive factors of TCZ efficacy. TCZ use within 6 days from symptoms onset, with CRP < 73.5 mg/L, LDH < 435.5 IU/L, and IL-6 < 103.5 pg/mL, had higher survival rates (P = 0.008, P = 0.009, P < 0.001, P < 0.001).

Conclusion

This study highlights the survival benefits of early TCZ use and the predicative role of cytokines levels in predicting TCZ efficacy in kidney transplant recipients with severe COVID-19 infection.

Introduction

Effective mobilization of Stem Cells(SCs) to peripheral blood (PB) is crucial for obtaining sufficient CD34⁺ cell numbers via apheresis. The ratio of pre-apheresis PB CD34⁺ cells is the best parameter for predicting the product CD34⁺ cell count. However, quantitating CD34⁺ PB cells requires flow cytometry, which usually takes two or more hours to obtain the results. We hypothesized that the product CD34⁺ cell count could be predicted using the counts of white blood cells (WBCs), mononuclear cells (MNCs), and pre-apheresis CD34⁺ cells. A formula that achieves this would substantially affect the efficiency and effectiveness of apheresis. We, therefore, aimed to estimate the number of CD34⁺ cells in the product using a formula that incorporates pre-apheresis PB WBC, MNC, and CD34⁺ cell counts and product WBC and MNC counts.

Methods

We examined the results of 373 leukapheresis procedures for SC mobilization. Effective separation of CD34⁺ PBSCs (count/μL) via apheresis was estimated using the following formula: [Product WBC (count/μL) × MNC (count/μL) × pre-apheresis CD34⁺ cell (percentage/μL)] ÷ [PB WBC count/μL × PB MNC (count/μL)].

Results

A strong correlation was observed between the CD34⁺ cell count calculated using our formula and the post-apheresis CD34⁺ cell count measured via flow cytometry (R = 0.939, based on linear regression analysis). In the subgroup analysis, this correlation was observed for all the disease subgroups and healthy donors.

Conclusion

We developed a formula that predicts the product CD34⁺ cell count and is useful for determining whether a second apheresis procedure will be required.

Background

The severity of complications after hematopoietic stem cell transplantation (HSCT) is dictated by the degree of immune reconstitution. However, the connection between immune reconstitution and the prognosis of pediatric patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains unclear. Therefore, the aim of this study was to evaluate the impact of lymphocyte subsets in children diagnosed with refractory or relapsed acute myeloid leukemia (R/R-AML) after allo-HSCT.

Methods

We retrospectively investigated the prognosis and lymphocyte subsets at d 90 (D90) post-allo-HSCT in 130 children diagnosed with R/R-AML between September 2019 and October 2022 at the Children's Hospital of Soochow University. Lymphocyte subgroups were assessed by flow cytometric analysis on D90 and compared among human leukocyte antigen (HLA)-matched sibling donor HSCT (MSD) (n = 14), haploidentical donor HSCT (n = 94), and HLA-matched unrelated donor HSCT (n = 22) groups. The associations between the counts and frequencies of lymphocyte subgroups and prognosis were assessed.

Results

In the MSD group, CD4+ T cell frequency and count were the highest (P < 0.001). Among the examined lymphocyte subsets, a lower proportion of CD4+ T cells (<14.535 %) at D90 correlated with a higher risk of cytomegalovirus infection (P = 0.002). A higher CD4+ T cell count (>121.39/μL) at D90 after HSCT was the single predictor of a lower fatality risk across all lymphocyte subgroups (univariate: P = 0.038 cut-off: 121.39/μL; multivariate: P = 0.036). No association with relapse was observed.

Conclusions

CD4+ T cell count may be used to identify pediatric patients with R/R-AML with a greater mortality risk early after HSCT.

Objectıves

This study investigates whether Cloprostenol, a synthetic prostaglandin analog, could protect against ischemia/reperfusion (IR) injury in rat ovaries.

Methods

Adult female rats were divided into four groups: Sham groups, ischemia (IS) groups, ischemia/reperfusion (IR) groups, and Cloprostenol-treated (CT) groups. The IR injury model was established by clamping the ovarian pedicle for a specified period, followed by reperfusion. The CT group received a pre-treatment of Cloprostenol before inducing ischemia. Ovarian tissues were collected for histological, and immunohistochemical examination.

Results

The IS group exhibited severe morphological damage to ovarian tissues, including disrupted tissue architecture and increased apoptosis (p < 0.001). In contrast, the CT group displayed significantly improved ovarian histology, with notable preservation of ovarian tissue and reduced apoptotic activity (p < 0.01). Immunohistochemical analysis revealed that the levels of 8-Hydroxy-2-deoxyguanosine (8-OHdG), Caspase 3, Cyclooxygenase 2 (COX-2), and Interleukin 1 beta (IL-1β) staining, which were elevated in the IS and IR groups, were significantly diminished in the CT group (p < 0.05).

Conclusıon

Cloprostenol administration before IR injury in rat ovaries demonstrated a remarkable protective effect by improving histological damage and reducing DNA damage inflammation. These results highlight the therapeutic potential of Cloprostenol in safeguarding ovarian health against IR.

Background

Normothermic ex vivo liver perfusion (NEVLP) is an exciting strategy to preserve livers prior to transplant, however, the effects of NEVLP on the phenotype of tissue-resident immune cells is largely unknown. The presence of tissue-resident memory T cells (TRM) in the liver may protect against acute rejection and decrease allograft dysfunction. Therefore, we investigated the effects of NEVLP on liver TRMs and assessed the ability of anti-inflammatory cytokines to reduce TRM activation during NEVLP.

Methods

Rat livers underwent NEVLP with or without the addition of IL-10 and TGF-β. Naïve and cold storage livers served as controls. Following preservation, TRM T cell gene expression profiles were assessed through single cell RNA sequencing (scRNA-seq). Differential gene expression analysis was performed with Wilcoxon rank sum test to identify differentially expressed genes (DEGs) associated with a specific treatment group. Using the online Database for Annotation, Visualization and Integrated Discovery (DAVID), gene set enrichment was then conducted with Fisher's exact test on DEGs to highlight differentially regulated pathways and functional terms associated with treatment groups.

Results

Through scRNA-seq analysis, an atlas of liver-resident memory T cell subsets was created for all livers. TRM T cells could be identified in all livers, and through scRNA-seq, DEG was identified with Wilcoxon rank sum test at FDR < 0.05. Based on the gene set enrichment analysis of DEGs using Fisher's exact test, NEVLP is associated with downregulation of multiple gene enrichment pathways associated with surface proteins. Furthermore, NEVLP with anti-inflammatory cytokines was associated with down regulation of 52 genes in TRM T cells when compared to NEVLP alone (FDR <0.05), most of which are pro-inflammatory.

Conclusion

This is the first study to create an atlas of liver TRM T cells in the rat liver undergoing NEVLP and demonstrate the effects of NEVLP on liver TRM T cells at the single cell gene expression level.

The reportedly poor outcome of late-onset idiopathic pneumonia syndrome (IPS) necessitates new approaches to its treatment. A 55-year-old man who had undergone allogeneic hematopoietic cell transplantation (allo-HCT) for myelodysplastic syndrome 1 year ago developed dyspnea with acute skin graft-versus-host disease (GVHD) flare-up while tapering immunosuppressive agents. He presented with acute respiratory distress syndrome with ground-glass opacities in the right upper and left lower lobes. All infectious tests, including multiplex polymerase chain reaction of nasal wash, were negative, and broad-spectrum antibiotic therapy was refractory. The patient was diagnosed with late-onset IPS and was refractory to methylprednisolone pulse therapy. He then showed a favorable response to mesenchymal stem cell (MSC) infusion. After eight infusions of MSCs, he had no IPS recurrence for over one year. Recently, preclinical studies have reported the potential therapeutic utility of MSC infusion for treating IPS, and our case supports its potential for treating late-onset IPS.

We have recently developed a model of pancreatic islet transplantation into a decellularized pancreatic tail in rats. As the pancreatic skeletons completely lack endothelial cells, we investigated the effect of co-transplantation of mesenchymal stem cells and endothelial cells to promote revascularization.

Decellularized matrix of the pancreatic tail was prepared by perfusion with Triton X-100, sodium dodecyl sulfate and DNase solution. Isolated pancreatic islets were infused into the skeletons via the splenic vein either alone, together with adipose tissue–derived mesenchymal stem cells (adMSCs), or with a combination of adMSCs and rat endothelial cells (rat ECs). Repopulated skeletons were transplanted into the subcutaneous tissue and explanted 9 days later for histological examination. Possible immunomodulatory effects of rat adMSCs on the survival of highly immunogenic green protein–expressing human ECs were also tested after their transplantation beneath the renal capsule. The immunomodulatory effects of adMSCs were also tested in vitro using the Invitrogen Click-iT EdU system.

In the presence of adMSCs, the proliferation of splenocytes as a response to phytohaemagglutinin A was reduced by 47% (the stimulation index decreased from 1.7 to 0.9, P = 0.008) and the reaction to human ECs was reduced by 58% (the stimulation index decreased from 1.6 to 0.7, P = 0.03). Histological examination of the explanted skeletons seeded only with the islets showed their partial disintegration and only a rare presence of CD31-positive cells. However, skeletons seeded with a combination of islets and adMSCs showed preserved islet morphology and rich vascularity. In contrast, the addition of syngeneic rat ECs resulted in islet-cell necrosis with only few endothelial cells present. Live green fluorescence–positive endothelial cells transplanted either alone or with adMSCs were not detected beneath the renal capsule.

Though the adMSCs significantly reduced in vitro proliferation stimulated by either phytohaemagglutinin A or by xenogeneic human ECs, in vivo co-transplanted adMSCs did not suppress the post-transplant immune response to xenogeneic ECs. Even in the syngeneic model, ECs co-transplantation did not lead to sufficient vascularization in the transplant area. In contrast, islet co-transplantation together with adMSCs successfully promoted the revascularization of extracellular matrix in the subcutaneous tissue.

Allograft rejection, accompanied by a rise in proinflammatory cytokines, is a leading cause of morbidity and mortality after lung transplantation. Immunosuppressive treatments are routinely employed as an effective way to prevent rejection, however, there is still an unmet need to develop new strategies to reduce the damage caused to transplanted organs by innate inflammatory responses. Recent research has shown that activating the vagus nerve's efferent arm regulates cytokine production and improves survival in experimental conditions of cytokine excess, such as sepsis, hemorrhagic shock, ischemia-reperfusion injury, among others. The cholinergic anti-inflammatory pathway can provide a localized, fast, and discrete response to inflammation by controlling the neuroimmune response and preventing excessive inflammation. This review intends to assess and discuss, the influence of noninvasive vagal nerve stimulation for prophylactic measures and supporting treatment in patients undergoing organ transplantation rejection with a prominent T-cell mediated immune response as a means of attenuating inflammation and leukocyte infiltration of the graft vessels.