The influence of exposure to immunosuppressive treatment during pregnancy on renal function and rate of apoptosis in native kidneys of female Wistar rats

Pregnancy puts a significant additional strain on kidneys. The aim of our study was to investigate the impact of immunosuppressive drugs on changes in native kidneys in female Wistar rats after exposure during pregnancy. The study was conducted on 32 dams, subjected to immunosuppressive regimens commonly used in the therapy of human kidney transplant recipients (cyclosporine A, mycophenolate mofetil and prednisone; tacrolimus, mycophenolate mofetil and prednisone; cyclosporine A, everolimus and prednisone). The animals received drugs for 2 weeks before pregnancy and during 3 weeks of pregnancy. In all treated dams lower body weight (but not kidney mass) and alterations in serum sodium and chloride ions were found; serum creatinine concentration was increased in dams treated with cyclosporine A, everolimus and prednisone. All treatment groups of dams showed increased apoptosis in the distal tubules. In histological examination the changed intensity of acidophilic or basophilic cytoplasm of epithelial cells was found in kidneys of rats treated with calcineurin inhibitors, mycophenolate mofetil and prednisone. All immunosuppressive regimens caused abnormalities affecting nephron tubules. Regimens containing calcineurin inhibitors and mycophenolate mofetil caused higher rate of apoptosis and more pronounced histopathological changes. Regimen based on everolimus despite the lower rate of apoptosis in the proximal tubules and lower accumulation of kidney injury markers revealed higher serum creatinine concentration. Thus, interpretation which combination of drugs is better or worse for long-lasting functioning of kidneys in pregnant females requires further studies.     

Anti-CD45RB monoclonal antibody-mediated transplantation tolerance

Currently, lifelong immunosuppression is required for organ transplant recipients. The majority of transplant recipients will eventually develop chronic rejection with resultant graft loss, despite treatment with powerful immunosuppressive agents. These agents are also associated with numerous toxicities including reduced immunity against infection and malignancy. Therefore, the central goal in transplant science is to devise tolerance strategies in an attempt to establish a state of prolonged non-reactivity against the allograft, accompanied with preservation of an intact immune system. Although predictable tolerance induction has been elusive, we found that short course of the novel immunomodulatory agent, anti-CD45RB monoclonal antibody, leads to indefinite acceptance of renal allografts in mice, and has been shown to markedly prolong allograft survival in primates. We review the current state of development of this antibody, and the progress made in defining its mechanism of action.     

Enfermedades invasoras por hongos levaduriformes en el receptor de un trasplante de órgano sólido

Invasive yeast diseases are uncommon nowadays in solid organ transplant recipients. Invasive candidiasis (2%) usually presents during the first month after transplantation in patients with risk factors. Both common and transplant-specific risk factors have been identified, allowing very efficacious targeted prophylaxis strategies. The most common clinical presentations are fungaemia and local infections near the transplantation area. Cryptococcosis is usually a late infection. Its incidence remains stable and the specific risk factors have not been identified. When cryptococcosis is detected very early, transmission with the allograft should be considered. The most common clinical presentations include meningitis, pneumonia, and disseminated infection. Intracranial hypertension and immune reconstitution syndrome have to be considered.No therapeutic clinical trials have been conducted in solid organ transplant recipients, thus treatment recommendations are derived from data obtained from the general population. It is particularly important to consider the possibility of drug-drug interactions, mainly between azoles and calcineurin inhibitors. Both invasive candidiasis and cryptococcosis increase the mortality significantly in solid organ transplant recipients.     

Regulatory T cells induced by 1 alpha,25-dihydroxyvitamin D3 and mycophenolate mofetil treatment mediate transplantation tolerance

1alpha,25-dihydroxyvitamin D3, the active form of vitamin D3, and mycophenolate mofetil, a selective inhibitor of T and B cell proliferation, modulate APC function and induce dendritic cells (DCs) with a tolerogenic phenotype. Here we show that a short treatment with these agents induces tolerance to fully mismatched mouse islet allografts that is stable to challenge with donor-type spleen cells and allows acceptance of donor-type vascularized heart grafts. Peritransplant macrophages and DCs from tolerant mice express down-regulated CD40, CD80, and CD86 costimulatory molecules. In addition, DCs from the graft area of tolerant mice secrete, upon stimulation with CD4+ cells, 10-fold lower levels of IL-12 compared with DCs from acutely rejecting mice, and induce a CD4+ T cell response characterized by selective abrogation of IFN-gamma production. CD4+ but not CD8+ or class II+ cells from tolerant mice, transferred into naive syngeneic recipients, prevent rejection of donor-type islet grafts. Graft acceptance is associated with impaired development of IFN-gamma-producing type 1 CD4+ and CD8+ cells and an increased percentage of CD4+CD25+ regulatory cells expressing CD152 in the spleen and in the transplant-draining lymph node. Transfer of CD4+CD25+ cells from tolerant but not naive mice protects 100% of the syngeneic recipients from islet allograft rejection. These results demonstrate that a short treatment with immunosuppressive agents, such as 1alpha,25-dihydroxyvitamin D3/mycophenolate mofetil, induces tolerance to islet allografts associated with an increased frequency of CD4+CD25+ regulatory cells that can adoptively transfer transplantation tolerance.     

Development of tolerogenic strategies in the clinic

The study of tolerance in the clinic can be divided into three areas: (i) focused evaluation of existing tolerant transplant recipients as to their mechanism of tolerance; (ii) prospective tolerance trials, such as combined bone marrow and kidney transplantation as well as T cell depletion followed by subsequent weaning of immunosuppression; and (iii) immunologic assays to assess the likelihood of rejection or tolerance. Frankly, a very small number of patients have been transplanted with the intention of removing all immunosuppressive therapy, but several clinical trials with this aim are currently in progress, largely sponsored by the Immune Tolerance Network, a joint venture between the National Institutes of Health and the Juvenile Diabetes Research Foundation. Similarly, a reliable assay to assess tolerance has not yet been developed but a variety of approaches towards assessing rejection, and in some cases tolerance, are being developed. It would be accurate to state that many of the experimental and preclinical approaches to the induction of tolerance have resulted in better immunosuppression for human transplantation, but reliable tolerance strategies in humans have not yet been achieved. Combined bone marrow and kidney transplantation may be considered as one exception to this, but such a strategy is not generally applicable to the vast majority of solid organ transplant recipients. This review will summarize efforts to date, particularly focusing on kidney transplantation.     

Protein—drug complexes important for immunoregulation and organ transplantation

Recently, two structures of the Ser/Thr phosphorylase calcineurin in complex with FK506 and its cognate immunophilin, FKBP12, have been reported, both solved by small pharmaceutical companies focused on structure-based drug design. A realization, however, that the toxicities associated with calcineurin-mediated immunosuppressants might be mechanism based has driven the current interest in alternative approaches to autoimmunity prophylaxis and preventing transplant rejection. Regulatory approval in 1995 of the immunosuppressant prodrug mycophenolate mofetil, whose active metabolite, mycophenolic acid, inhibits inosine monophosphate dehydrogenase, has focused attention on the potential significance of the de novo purine-biosynthesis pathway as a target for immunosuppressive drugs, leading ultimately to the solution of enzyme structure as a drug design target. As this and other clinically relevant targets are discovered, elaborated and refined via the activity of their cognate agents (as was the case for the phosphatase calcineurin via the activity of cyclosporin), a critical opportunity should ensue for structural biology to exert a profound effect on the future development of these therapies.     

Use of EQUORAL in de novo renal transplant recipients

This paper presents our experience to date with using a cyclosporine formulation Equoral (IVAX Pharmaceuticals) together with mycophenolate mofetil plus a steroid immunosuppressive regimen in the treatment of de novo renal transplant recipients. Ten cadaveric donor renal transplant recipients of mean age 51.6 years (range 37-66) were followed up over 6 months for the development of rejection attacks and side effects. All patients received prednisolone, mycophenolate mofetil (1 g/day during the first 5 days posttransplant and then 20 mg/kg/day) plus cyclosporine (3 mg/kg/day). Biopsy proven acute rejection episodes were observed in 2 out of 10 patients (20%). Six months patient as well as renal graft survival rate was 100%. The development of graft function was immediate after transplantation. The mean serum creatinine levels were gradually decreased. Over the 6-month posttransplant period, the function of the graft was satisfactory and stable. The majority of observed adverse events were those commonly reported with the use of cyclosporine and they resolved with a reduction in cyclosporine dose. Equoral treatment demonstrated an acceptable safety profile with maintenance of adequate renal function without incidence of malignancy/lymphoproliferative disease or serious infections. In conclusion, Equoral plus mycophenolate mofetil immunosuppression seems effective and safe on terms acute rejection rates, patient and renal graft survival rates and side profiles.     

Cyclosporin A: a powerful immunosuppressant.

Cyclosporin A (CyA) is a powerful immunosuppressive agent whose lack of myelotoxicity makes it unique among nonsteroidal drugs currently given for immunosuppression. It has been used with initial success in recipients of kidney, liver, bone marrow and pancreas transplants, and it may also have clinical application in the treatment of autoimmune disorders. In regard to its use in transplant recipients, there are many remaining questions about its mechanism of action, the optimum dose, whether it should be used alone or with other immunosuppressants, whether it can suppress chronic rejection and what its long-term side effects may be. These questions can only be answered by further careful laboratory investigation and controlled clinical trials. Until then, CyA should only be administered in centres experienced in its use.     

Immunomodulatory effects of mesenchymal stem cells for the treatment of cardiac allograft rejection

Heart transplantation continues to be the gold standard clinical intervention to treat patients with end-stage heart failure. However, there are major complications associated with this surgical procedure that reduce the survival prognosis of heart transplant patients, including allograft rejection, malignancies, infections, and other complications that arise from the use of broad-spectrum immunosuppression drugs. Recent studies have demonstrated the use of mesenchymal stem cells (MSCs) against allotransplantation rejection in both in vitro and in vivo settings due to their immunomodulatory properties. Therefore, utilization of MSCs provides new and exciting strategies to improve heart transplantation and potentially reduce the use of broad-spectrum immunosuppression drugs while alleviating allograft rejection. In this review, we will discuss the current research on the mechanisms of cardiac allograft rejection, the physiological and immunological characteristics of MSCs, the effects of MSCs on the immune system, and immunomodulation of heart transplantation by MSCs.     

Antibody immunosuppressive therapy in solid organ transplant: Part II

The use of antibodies in transplantation dates back to 1986 when muromonab CD3, a monoclonal antibody (mAb) targeting CD3, was first approved for prevention and treatment of renal allograft rejection. These agents have largely been used in a brief adjunctive manner to provide immunosuppression during the initial period after solid organ transplantation or during an episode of acute rejection. Recent advances in our understanding of transplant immunology have allowed emergence of numerous new mAbs, targeting co-stimulatory signals, cell surface receptors and novel protein constructs. During the next decade, transplant professionals will increasingly require knowledge of the mechanisms and pharmacologic characteristics of these novel therapeutic agents.Key words: antibody, immunosuppression, transplantation, biologics, anti-adhesion     

Comparison of long-term immunosuppression for limb transplantation using cyclosporine, tacrolimus, and mycophenolate mofetil: implications for clinical composite tissue transplantation

This study compared the efficacy of long-term intermittent immunosuppression in preventing the rejection of a limb transplant across the strongest histocompatibility barrier in ACI --> Lewis rats using the conventional immunosuppressive agent cyclosporine-A and the newer immunosuppressive agents FK-506 (tacrolimus) and RS-61443 (mycophenolate mofetil). The recipient animals were immunosuppressed daily for 14 days postoperatively, followed by long-term intermittent, twice-weekly immunosuppression using cyclosporine 25 mg/kg, RS-61443 30 mg/kg, or FK-506 2 mg/kg. All three immunosuppressive agents were able to prolong the rejection of the skin component of a limb transplant compared with nonimmunosuppressed controls. Eight of nine animals receiving cyclosporine immunosuppression showed signs of rejection of the skin component of the limb transplant while continuing to receive long-term immunosuppression and had a mean rejection time of 61.6 days. Seven of 10 animals immunosuppressed with RS-61443 also showed signs of rejection while still receiving immunosuppression, with a mean rejection time of 43.6 days. Nine of 10 animals receiving FK-506 immunosuppression showed no signs of skin rejection, but died of bacterial pneumonia between 273 and 334 days after transplantation, with a mean rejection time of 296.1 days. There was no statistically significant difference between intermittent immunosuppression with cyclosporine and RS-61443, but FK-506 was significantly superior to both cyclosporine and RS-61443. The implication of this study is that FK-506, but not cyclosporine or RS-61443, is probably the only single immunosuppressive agent capable of preventing rejection of the skin component of a composite tissue transplant. Combination immunosuppression with FK-506 and RS-61443, therefore, may be required to allow composite tissue transplantation to become a predictable clinical reality in the future.     

Deferred Pre-Emptive Switch from Calcineurin Inhibitor to Sirolimus Leads to Improvement in GFR and Expansion of T Regulatory Cell Population: A Randomized,Controlled Trial

Background

Measures to prevent chronic calcineurin inhibitor (CNI) toxicity have included limiting exposure by switching to sirolimus (SIR). SIR may favorably influence T regulator cell (T_reg) population. This randomized controlled trial compares the effect of switching from CNI to SIR on glomerular filtration rate (GFR) and T_reg frequency.

Methods

In this prospective open label randomized trial, primary living donor kidney transplant recipients on CNI-based immunosuppression were randomized to continue CNI or switched to sirolimus 2 months after surgery; 29 were randomized to receive CNI and 31 to SIR. All patients received mycophenolate mofetil and steroids. The main outcome parameter was estimated GFR (eGFR) at 180 days. T_reg population was estimated by flowcytometry.

Results

Baseline characteristics in the two groups were similar. Forty-eight patients completed the trial. At six months, patients in the SIR group had significantly higher eGFR as compared to those in the CNI group (88.94±11.78 vs 80.59±16.51 mL/min, p = 0.038). Patients on SIR had a 12 mL/min gain of eGFR of at the end of six months. Patients in the SIR group showed significant increase in T_reg population at 30 days, which persisted till day 180. There was no difference in the adverse events in terms of number of acute rejection episodes, death, infections, proteinuria, lipid profile, blood pressure control and hematological parameters between the two groups. Four patients taking SIR developed enthesitis. No patient left the study or switched treatment because of adverse event.

Conclusions

A deferred pre-emptive switch over from CNI to SIR safely improves renal function and T_reg population at 6 months in living donor kidney transplant recipients.Registered in Clinical Trials Registry of India (CTRI/2011/091/000034)     

Antibody immunosuppressive therapy in solid organ transplant

The use of antibodies in transplantation dates back to 1986 when muromonab CD3, a monoclonal antibody (mAb) targeting CD3, was first approved for prevention and treatment of renal allograft rejection. These agents have largely been used in a brief adjunctive manner to provide immunosuppression during the initial period after solid organ transplantation or during an episode of acute rejection. Recent advances in our understanding of transplant immunology have allowed emergence of numerous new mAbs, targeting co-stimulatory signals, cell surface receptors and novel protein constructs. During the next decade, transplant professionals will increasingly require knowledge of the mechanisms and pharmacologic characteristics of these novel therapeutic agents.     

Treatment with immunotoxin

T-cell depletion prior to or beginning at the time of transplantation has been shown to be a valuable adjunct to the induction of immunological unresponsiveness. Both total lymphoid irradiation and anti-lymphocyte globulin have been used for this purpose in experimental models of transplantation as well as in human organ transplant recipients. However, these methods of T-cell depletion are limited in their ability to deplete T cells selectively due to non-specific targeting and limited efficacy. A new anti-CD3 immunotoxin has been developed with a far more potent ability to deplete T cells selectively as measured by flow cytometry analysis of peripheral blood T lymphocytes as well as lymph node lymphocytes. This immunotoxin is well tolerated by rhesus monkeys when administered in vivo. When administered as a single immunosuppressive agent pretransplant, it substantially promotes allograft survival, inducing tolerance in at least one-third of recipients as measured by subsequent acceptance of donor skin grafts and rejection of third-party skin grafts. When administered on the day of transplant in combination with steroid pretreatment and a brief course of deoxyspergualin or mycophenolate mofetil (4 to 14 days), long-term unresponsiveness is also produced and in a more reliable manner than using immunotoxin alone. A new immunotoxin directed at the human CD3epsilon has been developed with excellent potency in T-cell killing and lacking the Fc portion of the CD3 antibody. This construct may be useful for T-cell depletion in humans and has a potential application in tolerance induction in human organ transplantation. Lessons learned from anti-CD3 immunotoxin in the non-human primate model to date include (i) profound (2-3 log) depletion of T-cells can be accomplished safely without inducing lymphoma or infection, (ii) such depletion is a useful adjunct for tolerance induction to allogeneic organ transplants, and (iii) tolerance to both allogeneic renal transplants and xenogeneic islet transplants has been accomplished using such strategies to date in non-human primates and in pigs. Immunotoxin may be useful for the induction of chimerism using strategies that include donor bone marrow infusion. Successful strategies for tolerance induction have also been developed using immunotoxin without the adjunct of donor bone marrow or stem cell infusion. Clinical application of immunotoxin will use a newly engineered construct with the potential for causing cytokine release, less susceptibility to neutralization by anti-diphtheria antibody and not dependent on chemical conjugation of an antibody and toxin. The usefulness of immunotoxin is directly related to its tremendous potency for depleting T cells. Based on results in nonhuman primates, it is anticipated that it will become a useful agent in tolerance induction in humans.     

A new cell-permeable peptide allows successful allogeneic islet transplantation in mice

Calcineurin inhibitors such as cyclosporine A and FK506 have been used for transplant therapy and treatment of autoimmune diseases. However, the inhibition of calcineurin outside the immune system has a number of side effects, including hyperglycemia. In the search for safer drugs, we developed a cell-permeable inhibitor of NFAT (nuclear factor of activated T cells) using the polyarginine peptide delivery system. This peptide provided immunosuppression for fully mismatched islet allografts in mice. In addition, it did not affect insulin secretion, whereas FK506 caused a dose-dependent decrease in insulin secretion. Cell-permeable peptides can thus provide a new strategy for drug development and may eventually be useful clinically.     

Immunomodulatory effects of BXL-01-0029, a less hypercalcemic vitamin D analogue, in human cardiomyocytes and T cells

Current immunosuppressive protocols have reduced rejection occurrence in heart transplantation; nevertheless, management of heart transplant recipients is accompanied by major adverse effects, due to drug doses close to toxic range. In allograft rejection, characterized by T-helper 1 (Th1) cell-mediated response, the CXCL10-CXCR3 axis plays a pivotal role in triggering a self-promoting inflammatory loop. Indeed, CXCL10 intragraft production, required for initiation and development of graft failure, supports organ infiltration by Th1 cells. Thus, targeting the CXCL10-CXCR3 axis while avoiding generalized immunosuppression, may be of therapeutic significance. Based on preclinical evidence for immunoregulatory properties of vitamin D receptor agonists, we propose that a less hypercalcemic vitamin D analogue, BXL-01-0029, might have the potential to contribute to rejection management. We investigated the effect of BXL-01-0029 on CXCL10 secretion induced by proinflammatory stimuli, both in human isolated cardiomyocytes (Hfcm) and purified CD4+ T cells. Mycophenolic acid (MPA), the active agent of mycophenolate mofetil, was used for comparison. BXL-01-0029 inhibited IFNγ and TNFα-induced CXCL10 secretion by Hfcm more potently than MPA, impairing cytokine synergy and pathways. BXL-01-0029 reduced also CXCL10 protein secretion and gene expression by CD4+ T cells. Furthermore, BXL-01-0029 did not exert any toxic effect onto both cell types, suggesting its possible use as a dose-reducing agent for conventional immunosuppressive drugs in clinical transplantation.     

Comparison of the efficacy and safety of Consupren solution and Sandimmun Neoral solution, 50 ml in stable heart transplant patients

Cyclosporine A (CyA) is a standard component of immunosuppressive regimen after heart transplantation in most centres. The widespread clinical use of cyclosporine-based immunosuppressive regimens since 1983 has led to significant improvements in the survival of cardiac allograft recipients due to decreased mortality from infections and rejections. (1-3) CyA has been shown to be safe and effective. Owing to its success when used after the heart transplantation the number of patients has also risen. This caused growing financial demands on health insurance companies in the Czech Republic where the immunosuppressive drugs are fully reimbursed. A prospective randomized study in 11 stable heart transplant patients was performed to compare the efficacy and safety of Consupren (IVAX-CR) a Sandimmun Neoral (Novartis) solution based immunosuppressive regimen. The results suggest that Consupren solution can be used as an alternative treatment to Sandimmun Neoral in CyA based regimen.     

Therapy of lupus nephritis: lessons learned from clinical research and daily care of patients

Despite numerous randomized clinical trials over the last three decades for identifying the optimal treatment option for lupus nephritis, renal involvement still significantly impacts the survival and quality of life of patients with lupus and the search for the ideal immunosuppressive regimen is far from complete. The purpose of this review is to summarize the major recent achievements in the field. More specifically, the following topics will be discussed: intravenous cyclophosphamide versus mycophenolate mofetil (MMF) for induction; azathioprine versus MMF for maintenance; targeted therapies. The review will address clues for optimal global care, such as the need for complete initial evaluation, the importance of patient education, the unmasking of non-compliance to therapy, the reason for an early treatment switch in non-responding patients, the need for prolonged immunosuppression, optimal renal protection, and prevention of cardiovascular disease and other comorbidities.     

Pharmacological therapies and drug development targeting SARS-CoV-2 infection

The development of therapies for SARS-CoV-2 infection, based on virus biology and pathology, and of large- and small-scale randomized controlled trials, have brought forward several antiviral and immunomodulatory drugs targeting the disease severity. Casirivimab/Imdevimab monoclonal antibodies and convalescent plasma to prevent virus entry, Remdesivir, Molnupiravir, and Paxlovid nucleotide analogs to prevent viral replication, a variety of repurposed JAK-STAT signaling pathway inhibitors, corticosteroids, and recombinant agonists/antagonists of cytokine and interferons have been found to provide clinical benefits in terms of mortality and hospitalization. However, current treatment options face multiple clinical needs, and therefore, in this review, we provide an update on the challenges of the existing therapeutics and highlight drug development strategies for COVID-19 therapy, based on ongoing clinical trials, meta-analyses, and clinical case reports.