A narrow T cell receptor repertoire instructs thymic differentiation of MHC class Ib-restricted CD8+ regulatory T cells.

Although most CD8+ T cells are equipped to kill infected or transformed cells, a subset may regulate immune responses and preserve self-tolerance. Here, we describe a CD8 lineage that is instructed to differentiate into CD8 T regulatory cells (Tregs) by a surprisingly restricted set of T cell receptors (TCRs) that recognize MHC-E (mouse Qa-1) and several dominant self-peptides. Recognition and elimination of pathogenic target cells that express these Qa-1-self-peptide complexes selectively inhibits pathogenic antibody responses without generalized immune suppression. Immunization with synthetic agonist peptides that mobilize CD8 Tregs in vivo efficiently inhibit antigraft antibody responses and markedly prolong heart and kidney organ graft survival. Definition of TCR-dependent differentiation and target recognition by this lineage of CD8 Tregs may open the way to new therapeutic approaches to inhibit pathogenic antibody responses.

Uncovering a novel role of focal adhesion and interferon-gamma in cellular rejection of kidney allografts at single cell resolution.

Background: Kidney transplant recipients are currently treated with nonspecific immunosuppressants that cause severe systemic side effects. Current immunosuppressants were developed based on their effect on T-cell activation rather than the underlying mechanisms driving alloimmune responses. Thus, understanding the role of the intragraft microenvironment will help us identify more directed therapies with lower side effects. Methods: To understand the role of the alloimmune response and the intragraft microenvironment in cellular rejection progression, we conducted a Single nucleus RNA sequencing (snRNA-seq) on one human non-rejecting kidney allograft sample, one borderline sample, and T-cell mediated rejection (TCMR) sample (Banff IIa). We studied the differential gene expression and enriched pathways in different conditions, in addition to ligand-receptor (L-R) interactions. Results: Pathway analysis of T-cells in borderline sample showed enrichment for allograft rejection pathway, suggesting that the borderline sample reflects an early rejection. Hence, this allows for studying the early stages of cellular rejection. Moreover, we showed that focal adhesion (FA), IFNg pathways, and endomucin (EMCN) were significantly upregulated in endothelial cell clusters (ECs) of borderline compared to ECs TCMR. Furthermore, we found that pericytes in TCMR seem to favor endothelial permeability compared to borderline. Similarly, T-cells interaction with ECs in borderline differs from TCMR by involving DAMPS-TLRs interactions. Conclusion: Our data revealed novel roles of T-cells, ECs, and pericytes in cellular rejection progression, providing new clues on the pathophysiology of allograft rejection.

Non-Invasive Monitoring for Rejection in Kidney Transplant Recipients After SARS-CoV-2 mRNA Vaccination.

Introduction: Studies have shown reduced antiviral responses in kidney transplant recipients (KTRs) following SARS-CoV-2 mRNA vaccination, but data on post-vaccination alloimmune responses and antiviral responses against the Delta (B.1.617.2) variant are limited. Materials and methods: To address this issue, we conducted a prospective, multi-center study of 58 adult KTRs receiving mRNA-BNT162b2 or mRNA-1273 vaccines. We used multiple complementary non-invasive biomarkers for rejection monitoring including serum creatinine, proteinuria, donor-derived cell-free DNA, peripheral blood gene expression profile (PBGEP), urinary CXCL9 mRNA and de novo donor-specific antibodies (DSA). Secondary outcomes included development of anti-viral immune responses against the wild-type and Delta variant of SARS-CoV-2. Results: At a median of 85 days, no KTRs developed de novo DSAs and only one patient developed acute rejection following recent conversion to belatacept, which was associated with increased creatinine and urinary CXCL9 levels. During follow-up, there were no significant changes in proteinuria, donor-derived cell-free DNA levels or PBGEP. 36% of KTRs in our cohort developed anti-wild-type spike antibodies, 75% and 55% of whom had neutralizing responses against wild-type and Delta variants respectively. A cellular response against wild-type S1, measured by interferon-γ-ELISpot assay, developed in 38% of KTRs. Cellular responses did not differ in KTRs with or without antibody responses. Conclusions: SARS-CoV-2 mRNA vaccination in KTRs did not elicit a significant alloimmune response. About half of KTRs who develop anti-wild-type spike antibodies after two mRNA vaccine doses have neutralizing responses against the Delta variant. There was no association between anti-viral humoral and cellular responses.

Nanodelivery of Mycophenolate Mofetil to the Organ Improves Transplant Vasculopathy.

Inflammation occurring within the transplanted organ from the time of harvest is an important stimulus of early alloimmune reactivity and promotes chronic allograft rejection. Chronic immune-mediated injury remains the primary obstacle to the long-term success of organ transplantation. However, organ transplantation represents a rare clinical setting in which the organ is accessible ex vivo, providing an opportunity to use nanotechnology to deliver therapeutics directly to the graft. This approach facilitates the directed delivery of immunosuppressive agents (ISA) to target local pathogenic immune responses prior to the transplantation. Here, we have developed a system of direct delivery and sustained release of mycophenolate mofetil (MMF) to treat the donor organ prior to transplantation. Perfusion of a donor mouse heart with MMF-loaded PEG-PLGA nanoparticles (MMF-NPs) prior to transplantation abrogated cardiac transplant vasculopathy by suppressing intragraft pro-inflammatory cytokines and chemokines. Our findings demonstrate that ex vivo delivery of an ISA to donor organs using a nanocarrier can serve as a clinically feasible approach to reduce transplant immunity.

Targeted delivery of immune therapeutics to lymph nodes prolongs cardiac allograft survival.

The targeted delivery of therapeutic drugs to lymph nodes (LNs) provides an unprecedented opportunity to improve the outcomes of transplantation and immune-mediated diseases. The high endothelial venule is a specialized segment of LN vasculature that uniquely expresses peripheral node addressin (PNAd) molecules. PNAd is recognized by MECA79 mAb. We previously generated a MECA79 mAb-coated microparticle (MP) that carries tacrolimus. Although this MP trafficked to LNs, it demonstrated limited therapeutic efficacy in our transplant model. Here, we have synthesized a nanoparticle (NP) as a carrier of anti-CD3, and optimized the conjugation strategy to coat the NP surface with MECA79 mAb (MECA79-anti-CD3-NP) to enhance LN accumulation. As compared with nonconjugated NPs, a significantly higher quantity of MECA79-NPs accumulated in the draining lymph node (DLN). Many MECA79-NPs underwent internalization by T cells and dendritic cells within the LNs. Short-term treatment of murine cardiac allograft recipients with MECA79-anti-CD3-NP resulted in significantly prolonged allograft survival in comparison with the control groups. Prolonged graft survival following treatment with MECA79-anti-CD3-NP was characterized by a significant increase in intragraft and DLN Treg populations. Treg depletion abrogated the prolongation of heart allograft survival. We believe this targeted approach of drug delivery could redefine the methods of administering immune therapeutics in transplantation.

Repetitive ischemic injuries to the kidneys result in lymph node fibrosis and impaired healing.

The contribution of the kidney-draining lymph node (KLN) to the pathogenesis of ischemia-reperfusion injury (IRI) of the kidney and its subsequent recovery has not been explored in depth. In addition, the mechanism by which repetitive IRI contributes to renal fibrosis remains poorly understood. Herein, we have found that IRI of the kidney is associated with expansion of high endothelial venules (HEVs) and activation of fibroblastic reticular cells (FRCs) in the KLN, as demonstrated by significant expansion in the extracellular matrix. The lymphotoxin α signaling pathway mediates activation of FRCs, and chronic treatment with lymphotoxin ß receptor-immunoglobulin fusion protein (LTßr-Ig) resulted in marked alteration of the KLN as well as augmentation of renal fibrosis. Depletion of FRCs reduced T cell activation in the KLN and ameliorated renal injury in acute IRI. Repetitive renal IRI was associated with senescence of FRCs, fibrosis of the KLN, and renal scarring, which were ameliorated by FRC administration. Therefore, our study emphasizes the critical role of FRCs in both the initiation and repair phases of injury following IRI of the kidney.

Ischemia augments alloimmune injury through IL-6-driven CD4+ alloreactivity.

Ischemia reperfusion injuries (IRI) are unavoidable in solid organ transplantation. IRI augments alloimmunity but the mechanisms involved are poorly understood. Herein, we examined the effect of IRI on antigen specific alloimmunity. We demonstrate that ischemia promotes alloimmune activation, leading to more severe histological features of rejection, and increased CD4+ and CD8+ T cell graft infiltration, with a predominantly CD8+ IFNγ+ infiltrate. This process is dependent on the presence of alloreactive CD4+ T cells, where depletion prevented infiltration of ischemic grafts by CD8+ IFNγ+ T cells. IL-6 is a known driver of ischemia-induced rejection. Herein, depletion of donor antigen-presenting cells reduced ischemia-induced CD8+ IFNγ+ allograft infiltration, and improved allograft outcomes. Following prolonged ischemia, accelerated rejection was observed despite treatment with CTLA4Ig, indicating that T cell costimulatory blockade failed to overcome the immune activating effect of IRI. However, despite severe ischemic injury, treatment with anti-IL-6 and CTLA4Ig blocked IRI-induced alloimmune injury and markedly improved allograft survival. We describe a novel pathway where IRI activates innate immunity, leading to upregulation of antigen specific alloimmunity, resulting in chronic allograft injury. Based on these findings, we describe a clinically relevant treatment strategy to overcome the deleterious effect of IRI, and provide superior long-term allograft outcomes.

Regulation of T cell alloimmunity by PI3Kγ and PI3Kδ.

Phosphatidylinositol-3-kinases (PI3K) γ and δ are preferentially enriched in leukocytes, and defects in these signaling pathways have been shown to impair T cell activation. The effects of PI3Kγ and PI3Kδ on alloimmunity remain underexplored. Here, we show that both PI3Kγ -/- and PI3Kδ D910A/D910A mice receiving heart allografts have suppression of alloreactive T effector cells and delayed acute rejection. However, PI3Kδ mutation also dampens regulatory T cells (Treg). After treatment with low dose CTLA4-Ig, PI3Kγ -/- , but not PI3Κδ D910A/D910A , recipients exhibit indefinite prolongation of heart allograft survival. PI3Kδ D910A/D910A Tregs have increased apoptosis and impaired survival. Selective inhibition of PI3Kγ and PI3Kδ (using PI3Kδ and dual PI3Kγδ chemical inhibitors) shows that PI3Kγ inhibition compensates for the negative effect of PI3Kδ inhibition on long-term allograft survival. These data serve as a basis for future PI3K-based immune therapies for transplantation.Phosphatidylinositol-3-kinases (PI3K) γ and δ are key regulators of T cell signaling. Here the author show, using mouse heart allograft transplantation models, that PI3Kγ or PI3Kδ deficiency prolongs graft survival, but selective inhibition of PI3Kγ or PI3Kδ reveals alternative transplant survival outcomes post CTLA4-Ig treatment.

Brief treatment with a highly selective immunoproteasome inhibitor promotes long-term cardiac allograft acceptance in mice.

Constitutive proteasomes (c-20S) are ubiquitously expressed cellular proteases that degrade polyubiquitinated proteins and regulate cell functions. An isoform of proteasome, the immunoproteasome (i-20S), is highly expressed in human T cells, dendritic cells (DCs), and B cells, suggesting that it could be a potential target for inflammatory diseases, including those involving autoimmunity and alloimmunity. Here, we describe DPLG3, a rationally designed, noncovalent inhibitor of the immunoproteasome chymotryptic subunit ß5i that has thousands-fold selectivity over constitutive ß5c. DPLG3 suppressed cytokine release from blood mononuclear cells and the activation of DCs and T cells, diminished accumulation of effector T cells, promoted expression of exhaustion and coinhibitory markers on T cells, and synergized with CTLA4-Ig to promote long-term acceptance of cardiac allografts across a major histocompatibility barrier. These findings demonstrate the potential value of using brief posttransplant immunoproteasome inhibition to entrain a long-term response favorable to allograft survival as part of an immunomodulatory regimen that is neither broadly immunosuppressive nor toxic.

The early outcome of single-incision versus multi-port laparoscopic cholecystectomy.

BACKGROUND: Single-incision laparoscopic cholecystectomy (SILC) is a newly developed method of performing cholecystectomy and has been increasingly used. The aim of this study is to see if SILC has any advantages over conventional (three-port) laparoscopic cholecystectomy (CLC). MATERIALS AND METHODS: In this cross-sectional study, 52 patients who underwent SILC (group A) during the period from May 2011 to March 2013 were compared with 62 patients who underwent CLC (group B) at two centers affiliated to Shiraz University of Medical Sciences in Shiraz, Iran. Data were gathered on operation time, pre- and postoperative complications, patients' postoperative pain, pain reliever use, duration of hospital stay, and return to work, and these data were compared using SPSS software version 16. RESULTS: The mean age of patients was 38.01 ± 13.24 in group A and 44.82 ± 15.11 in group B. Mean body mass index (BMI) was 23.97 ± 4.78 and 26.22 ± 4.67 in groups A and B, respectively. The mean operation time was 76.4 ± 29.0 min in group A and 72.9 ± 24.1 min in group B (P = 0.496). Preoperative complications were 3.8% in group A and 0 in group B (P = 0.206). Postoperative complications were 17.3% in group A and 11.3% in group B (P = 0.423). The mean for early postoperative pain revealed no significant difference (P = 0.814), but the mean pain on discharge was significantly higher in group A patients (P = 0.034). Regarding the mean admission time and return to normal activity, we found no significant differences. CONCLUSION: SILC does not have any special advantages over CLC with regard to surgical outcomes, but it can be a safe alternative to CLC, especially in patients concerned about cosmoses.

PI3kα and STAT1 Interplay Regulates Human Mesenchymal Stem Cell Immune Polarization.

The immunomodulatory capacity of mesenchymal stem cells (MSCs) is critical for their use in therapeutic applications. MSC response to specific inflammatory cues allows them to switch between a proinflammatory (MSC1) or anti-inflammatory (MSC2) phenotype. Regulatory mechanisms controlling this switch remain to be defined. One characteristic feature of MSC2 is their ability to respond to IFNγ with induction of indoleamine 2,3-dioxygenase (IDO), representing the key immunoregulatory molecule released by human MSC. Here, we show that STAT1 and PI3Kα pathways interplay regulates IFNγ-induced IDO production in MSC. Chemical phosphoinositide 3-kinase (PI3K) pan-inhibition, PI3Kα-specific inhibition or shRNA knockdown diminished IFNγ-induced IDO production. This effect involved PI3Kα-mediated upregulation of STAT1 protein levels and phosphorylation at Ser727. Overexpression of STAT1 or of a constitutively active PI3Kα mutant failed to induce basal IDO production, but shifted MSC into an MSC2-like phenotype by strongly enhancing IDO production in response to IFNγ as compared to controls. STAT1 overexpression strongly enhanced MSC-mediated T-cell suppression. The same effect could be induced using short-term pretreatment of MSC with a chemical inhibitor of the counter player of PI3K, phosphatase and tensin homolog. Finally, downregulation of STAT1 abrogated the immunosuppressive capacity of MSC. Our results for the first time identify critical upstream signals for the induced production of IDO in MSCs that could be manipulated therapeutically to enhance their immunosuppressive phenotype.

Adipose tissue derived mesenchymal stem cell (AD-MSC) promotes skin wound healing in diabetic rats.

AIMS: Stem cells are a new hope to ameliorate impaired diabetic wound healing. The purpose of this study was to evaluate the effect of adipose tissue derived mesenchymal stem cells (AD-MSCs) on wound healing in a diabetic rat model. METHODS: Twenty-six rats became diabetic by a single intraperitoneal injection of streptozotocin. Six rats served as non-diabetic (non-DM). Diabetic rats were divided into two equal groups randomly; control and treatment. Six weeks later, a full-thickness circular excisional wound was created on the dorsum of each rat. AD-MSCs were injected intra-dermally around the wounds of treatment group. PBS was applied to control and non-DM groups. The wound area was measured every other day. After wound healing completion, full thickness skin samples were taken from the wound sites for evaluation of volume density of collagen fibers, length and volume density of vessels, and numerical density of fibroblasts by stereological methods. RESULTS: AD-MSCs accelerated wound healing rate in diabetic rats, but did not increase length and volume density of the vessels and volume density of the collagen fibers. AD-MSCs decreased the numerical density of fibroblasts. CONCLUSIONS: We concluded that AD-MSCs enhances diabetic wound healing rate probably by other mechanisms rather than enhancing angiogenesis or accumulating collagen fibers.

Azelnidipine, a new calcium channel blocker, promotes skin wound healing in diabetic rats.

OBJECTIVE: Impaired wound healing in diabetes is associated with decreased nitric oxide (NO) bioavailability in wound tissue. We hypothesized azelnidipine (AZL), a new calcium channel blocker with antioxidant properties, would enhance wound healing in streptozotocin-induced diabetic rats by restoring NO synthesis. METHODS: Twelve male rats were taken as non-diabetic group. Twenty four rats were taken and caused to be diabetic by a single streptozotocin injection. Diabetic rats were divided randomly to two groups: control and treatment. Half of non-diabetic and also diabetic rats (in each group of control and treatment) randomly served as excisional-wound model and the other half as nitrite-measurement model. Six weeks after causing diabetes, the excisional wound model underwent dorsal full-thickness excisional wounds (1 × 1 cm). After wound healing completion, full-thickness skin samples (1 × 1 cm) were taken from the wound sites for evaluation of stereological parameters. The nitrite-measurement model (6 wk after causing diabetes) underwent insertion of subcutaneous polyvinyl alcohol sponges in dorsum. The rats were killed 2 wk post-wounding, and wound fluid was analyzed. In the study, after wounding, the treatment groups were gavaged with AZL (3 mg/kg/d) and control and non-diabetic groups with AZL vehicle till euthanasia. RESULTS: AZL accelerated wound healing rate and also improved wound fluid NO level toward normal value in diabetic rats. Volume density of collagen fibers, numerical density of fibroblasts, and length density of vessels were increased in AZL-treated rats compared with control group. CONCLUSION: AZL administration promotes diabetic wound healing by stimulating NO production and enhancing histologic processes central to normal wound healing.