JAK3 inhibitor-based immunosuppression in allogeneic islet transplantation in cynomolgus monkeys

Long-term control of diabetes by tofacitinib-based immunosuppressive regimen after allo islet transplantation in diabetic rhesus monkeys that rejected previously transplanted porcine islets

Porcine islet xenotransplantation has been highlighted as an alternative to allo islet transplantation. Despite the remarkable progress that has been made in porcine-islet pre-clinical studies in nonhuman primates, immunological tolerance to porcine islets has not been achieved to date. Therefore, allo islet transplantation could be required after the failure of porcine islet xenotransplantation. Here, we report the long-term control of diabetes by allogeneic pancreatic islet transplantation in diabetic rhesus monkeys that rejected previously transplanted porcine islets. Four diabetic male rhesus monkeys received the porcine islets and then allo islets (5700-19 000 IEQ/kg) were re-transplanted for a short or long period after the first xeno islet rejection. The recipient monkeys were treated with an immunosuppressive regimen consisting of ATG, humira, and anakinra for induction, and sirolimus and tofacitinib for maintenance therapy. The graft survival days of allo islets in these monkeys were >440, 395, >273, and 127, respectively, similar to that in allo islet transplanted cynomolgus monkeys that received the same immunosuppressive regimen without xeno sensitization. Taken together, it is likely that prior islet xenotransplantation does not affect the survival of subsequent allo islets under clinically applicable immunosuppressants.

In silico computational drug discovery: a Monte Carlo approach for developing a novel JAK3 inhibitors

Inhibition of Janus kinase 3 (JAK3), a member of the JAK family of tyrosine kinases, remains an essential area of research for developing treatments for autoimmune diseases, particularly cancer and rheumatoid arthritis. The recent discovery of a new JAK3 protein, PDB ID: 4Z16, offers exciting possibilities for developing inhibitors capable of forming a covalent bond with the Cys909 residue, thereby contributing to JAK3 inhibition. A powerful prediction model was constructed and validated using Monte Carlo methods, employing various internal and external techniques. This approach resulted in the prediction of eleven new molecules, which were subsequently filtered to identify six compounds exhibiting potent pIC50 values. These candidates were then subjected to ADMET analysis, molecular docking (including reversible-reversible docking with tofacitinib, an FDA-approved drug, and reversible-irreversible docking for the newly designed compounds), molecular dynamics (MD) analysis for 300 ns, and calculation of free binding energy. The results suggested that these compounds hold promise as JAK3 inhibitors. In summary, the new compounds have exhibited favorable outcomes compared to other compounds across various modeling approaches. The collective findings from these investigations provide valuable insights into the potential therapeutic applications of covalent JAK3 inhibitors, offering a promising direction for the development of novel treatments for autoimmune disorders.Communicated by Ramaswamy H. Sarma.

The Innate Cellular Immune Response in Xenotransplantation

Xenotransplantation is very attractive strategy for addressing the shortage of donors. While hyper acute rejection (HAR) caused by natural antibodies and complement has been well defined, this is not the case for innate cellular xenogeneic rejection. An increasing body of evidence suggests that innate cellular immune responses contribute to xenogeneic rejection. Various molecular incompatibilities between receptors and their ligands across different species typically have an impact on graft outcome. NK cells are activated by direct interaction as well as by antigen dependent cellular cytotoxicity (ADCC) mechanisms. Macrophages are activated through various mechanisms in xenogeneic conditions. Macrophages recognize CD47 as a "marker of self" through binding to SIRPα. A number of studies have shown that incompatibility of porcine CD47 against human SIRPα contributes to the rejection of xenogeneic target cells by macrophages. Neutrophils are an early responder cell that infiltrates xenogeneic grafts. It has also been reported that neutrophil extracellular traps (NETs) activate macrophages as damage-associated pattern molecules (DAMPs). In this review, we summarize recent insights into innate cellular xenogeneic rejection.

Therapeutic siRNAs Targeting the JAK/STAT Signalling Pathway in Inflammatory Bowel Diseases

BACKGROUND AND AIMS

Inflammatory bowel diseases are highly debilitating conditions that require constant monitoring and life-long medication. Current treatments are focused on systemic administration of immunomodulatory drugs, but they have a broad range of undesirable side-effects. RNA interference is a highly specific endogenous mechanism that regulates the expression of the gene at the transcript level, which can be repurposed using exogenous short interfering RNA [siRNA] to repress expression of the target gene. While siRNA therapeutics can offer an alternative to existing therapies, with a high specificity critical for chronically administrated drugs, evidence of their potency compared to chemical kinase inhibitors used in clinics is still lacking in alleviating an adverse inflammatory response.

METHODS

We provide a framework to select highly specific siRNA, with a focus on two kinases strongly involved in pro-inflammatory diseases, namely JAK1 and JAK3. Using western-blot, real-time quantitative PCR and large-scale analysis, we assessed the specificity profile of these siRNA drugs and compared their efficacy to the most recent and promising kinase inhibitors for Janus kinases [Jakinibs], tofacitinib and filgotinib.

RESULTS

siRNA drugs can reach higher efficiency and selectivity at lower doses [5 pM vs 1 µM] than Jakinibs. Moreover, JAK silencing lasted up to 11 days, even with 6 h pulse transfection.

CONCLUSIONS

The siRNA-based drugs developed hold the potential to develop more potent therapeutics for chronic inflammatory diseases.

Recent advances on signaling pathways and their inhibitors in rheumatoid arthritis

Rheumatoid arthritis (RA) is characterized by systemic synovitis leading to joint destruction in which imbalances in pro-inflammatory and anti-inflammatory cytokines promote the induction of autoimmunity. Some pro-inflammatory cytokines can trigger the signaling pathways which responsible for immune-mediated inflammation in RA, and the activated signaling pathways produce pro-inflammatory cytokines, resulting in aggravation of RA. Hence, understanding of the signaling pathways and their inhibitors might be advantageous in the development of therapeutic targets and new drugs for RA. In the current review, we summarize the signaling pathways involved in the pathogenesis of RA as well as the potential role of specific inhibitors in its management. We hope this paper may serve a reference for future studies on signaling pathways implicated in the pathogenesis of RA and benefit the treatment of RA.

Optimal allogeneic islet dose for transplantation in insulin-dependent diabetic Macaca fascicularis monkeys

Many groups are working to improve the results of clinical allogeneic islet transplantation in a primate model. However, few studies have focused on the optimal islet dose for achieving normal glycemia without exogenous insulin after transplantation in primate models or on the relationship between rejection and islet amyloid polypeptide (IAPP) expression. We evaluated the dose (10,000, 20,000, and > 25,000 islet equivalents (IEQ)/kg) needed to achieve normal glycemia without exogenous insulin after transplantation using eleven cynomolgus monkeys, and we analyzed the characteristics exhibited in the islets after transplantation. 10,000 IEQ/kg (N = 2) failed to control blood glucose level, despite injection with the highest dose of exogenous insulin, and 20,000 IEQ/kg group (N = 5) achieved unstable control, with a high insulin requirement. However, 25,000 IEQ/kg (N = 4) achieved normal glycemia without exogenous insulin and maintained it for more than 60 days. Immunohistochemistry results from staining islets found in liver biopsies indicated that as the number of transplanted islets decreased, the amount of IAPP accumulation within the islets increased, which accelerated CD3⁺ T cell infiltration. In conclusion, the optimal transplantation dose for achieving a normal glycemia without exogenous insulin in our cynomolgus monkey model was > 25,000 IEQ/kg, and the accumulation of IAPP early after transplantation, which depends on the transplanted islet dose, can be considered one factor in rejection.

Novel Immunomodulatory Approaches for Porcine Islet Xenotransplantation

PURPOSE OF REVIEW

Porcine islet xenotransplantation is a promising alternative to overcome the shortage of organ donors. For the successful application of islet xenotransplantation, robust immune/inflammatory responses against porcine islets should be thoroughly controlled. Over the last few decades, there have been numerous attempts to surmount xenogeneic immune barriers. In this review, we summarize the current progress in immunomodulatory therapy for the clinical application of porcine islet xenotransplantation.

RECENT FINDINGS

Long-term graft survival of porcine islets was achieved by using anti-CD154 Ab-based regimens in a preclinical non-human primate (NHP) model. However, owing to a serious complication of thromboembolism in clinical trials, the development of an anti-CD154 Ab-sparing immunosuppressant procedure is required. The efficacy of new immunosuppressive practices that employ anti-CD40 Abs or other immunosuppressive reagents has been tested in a NHP model to realize their utility in porcine islet xenotransplantation. The recent progress in the development of immunomodulatory approaches, including the immunosuppressive regimen, which enables long-term graft survival in a pig-to-non-human primate islet xenotransplantation model, with their potential clinical applicability was reviewed.

Immune Protection of Stem Cell-Derived Islet Cell Therapy for Treating Diabetes

Insulin injection is currently the main therapy for type 1 diabetes (T1D) or late stage of severe type 2 diabetes (T2D). Human pancreatic islet transplantation confers a significant improvement in glycemic control and prevents life-threatening severe hypoglycemia in T1D patients. However, the shortage of cadaveric human islets limits their therapeutic potential. In addition, chronic immunosuppression, which is required to avoid rejection of transplanted islets, is associated with severe complications, such as an increased risk of malignancies and infections. Thus, there is a significant need for novel approaches to the large-scale generation of functional human islets protected from autoimmune rejection in order to ensure durable graft acceptance without immunosuppression. An important step in addressing this need is to strengthen our understanding of transplant immune tolerance mechanisms for both graft rejection and autoimmune rejection. Engineering of functional human pancreatic islets that can avoid attacks from host immune cells would provide an alternative safe resource for transplantation therapy. Human pluripotent stem cells (hPSCs) offer a potentially limitless supply of cells because of their self-renewal ability and pluripotency. Therefore, studying immune tolerance induction in hPSC-derived human pancreatic islets will directly contribute toward the goal of generating a functional cure for insulin-dependent diabetes. In this review, we will discuss the current progress in the immune protection of stem cell-derived islet cell therapy for treating diabetes.

Islet transplantation modulates macrophage to induce immune tolerance and angiogenesis of islet tissue in type I diabetes mice model

Objective To investigate the dual mechanism of islet transplantation in T1D by regulating the immune tolerance of macrophages and inducing the neovascularization.

Methods NC group, T1D model group and T1D model + islet group were constructed. Then, the abdominal aorta blood of abdominal aorta and islet tissue were collected. ELISA was performed to detect the level of IL-1Rα, IL-1α, IL-1β, CXCL2, MCP1, TNF-α and IL-10. Flow cytometry was used to measure the content of M1 and M2 macrophages. HE staining indicated the pathological characteristics of islet. IHC and WB were applied to determine the protein levels of IGF1R, FGFR2 or VEGFA as well as IGF1R, GRB2, EGFR, PTPN1, JAK2, STAT3, Caspase-1, Bcl2 respectively.

Results Islet transplantation in T1D stimulated the expression of IL-1Rα, IL-1α, IL-1β, CXCL2, MCP1, TNF-α and IL-10 in abdominal aorta blood, changed the content of MHCII⁺CD206^-M1 and MHCII⁺CD206⁺M2 macrophages, reduced the pathological features and the infiltration of immunocytes, promoted the expression of IGF1R, FGFR2 and VEGFA, eliminated cell apoptosis and induced the neovascularization in islet grafts.

Conclusions Islet transplantation is an effective strategy for the treatment of T1D. It can increase the content of M2 macrophages whose immune tolerance can elevate the survival of islet grafts, reduce the inflammatory responses mediated by macrophages, promote the neovascularization and eliminate the cell apoptosis of islet grafts.

COVID-19 and islet transplantation: Different twins

For those who work in the field of islet transplantation, the microvascular coronavirus disease 2019 (COVID-19) lung vessels obstructive thrombo-inflammatory syndrome (recently referred to as MicroCLOTS) is familiar, as one cannot fail to recognize the presence of similarities with the instant blood mediated inflammatory reaction (IBMIR) occurring in the liver hours and days after islet infusion. Evidence in both MicroCLOTS and IBMIR suggests the involvement of the coagulation cascade and complement system activation and proinflammatory chemokines/cytokines release. Identification and targeting of pathway(s) playing a role as "master regulator(s)" in the post-islet transplant detrimental inflammatory events could be potentially useful to suggest innovative COVID-19 treatments and vice versa. Scientific organizations across the world are fighting the COVID-19 pandemic. Islet transplantation, and more generally the transplantation scientific community, could contribute by suggesting strategies for innovative approaches. At the same time, in the near future, clinical trials in COVID-19 patients will produce an enormous quantity of clinical and translational data on the control of inflammation and complement/microthrombosis activation. These data will represent a legacy to be transformed into innovation in the transplant field. It will be our contribution to change a dramatic event into advancement for the transplant field and ultimately for our patients.