Organ Transplant Rejection Research Articles

Should Transplant Nephrology Pursue Recognition from the Accreditation Council for Graduate Medical Education (ACGME)?

Kidney transplant is not only the best treatment for patients with advanced kidney disease but it also reduces health care expenditure. The management of transplant patients is complex as they require special care by transplant nephrologists who have expertise in assessing transplant candidates, understand immunology and organ rejection, have familiarity with perioperative complications, and have the ability to manage the long-term effects of chronic immunosuppression. This skill set at the intersection of multiple disciplines necessitates additional training in Transplant Nephrology. Currently, there are more than 250,000 patients with a functioning kidney allograft and over 100,000 waitlisted patients awaiting kidney transplant, with a burgeoning number added to the kidney transplant wait list every year. In 2022, more than 40,000 patients were added to the kidney wait list and more than 25,000 received a kidney transplant. The Advancing American Kidney Health Initiative, passed in 2019, is aiming to double the number of kidney transplants by 2030 creating a need for additional transplant nephrologists to help care for them. Over the past decade, there has been a decline in the Nephrology-as well Transplant Nephrology-workforce due to a multitude of reasons. The American Society of Transplantation Kidney Pancreas Community of Practice created a workgroup to discuss the Transplant Nephrology workforce shortage. In this article, we discuss the scope of the problem and how the Accreditation Council for Graduate Medical Education recognition of Transplant Nephrology Fellowship could at least partly mitigate the Transplant Nephrology work force crisis.

Low-dose Interleukin-2 Therapy: Fine-tuning Treg in Solid Organ Transplantation?

Regulatory T cells (Treg), a subset of CD4 + T cells, are potent regulators of immune reactions, which have been shown to be a promising therapeutic alternative to toxic immunosuppressive drugs. Data support the utility of Treg in managing immunopathologies, including solid organ transplant rejection, graft-versus-host disease, and autoimmune disorders. Notably, reports suggest that interleukin-2 (IL-2) is critical to survival of Treg, which constitutively express high levels of CD25, that is, the IL-2 receptor α-chain, and are exquisitely sensitive to IL-2, even at very low concentrations in contrast to effector T cells, which only upregulate IL-2 receptor α-chain on activation. This has led to the notion of using low doses of exogenous IL-2 therapeutically to modulate the immune system, specifically Treg numbers and function. Here, we summarize developments of clinical experience with low-dose IL-2 (LD-IL-2) as a therapeutic agent. So far, no clinical data are available to support the therapeutic use of LD-IL-2 therapy in the solid organ transplant setting. For the latter, fine-tuning by biotechnological approaches may be needed because of the narrow therapeutic window and off-target effects of LD-IL-2 therapy and so to realize the therapeutic potential of this molecule.

P-79 Graves’ Disease associated with alemtuzumab use for multiple sclerosis

Abstract Introduction Alemtuzumab was the first humanized monoclonal antibody to be created and is directed against CD52, a lymphocyte cell surface marker of unknown function. It has been used to treat leukemia and organ transplant rejection. More recently, alemtuzumab has been demonstrated to be highly effective in treating relapsing-remitting multiple sclerosis (MS) disease. Thyroid disease develops in approximately 20% of patients using alemtuzumab for MS, and Graves’ disease is the most common among them. Graves’ disease has not been reported in the use of alemtuzumab for reasons other than MS. Clinical Case A 28-year-old female patient with a 10 year history of MS had been treated with pulse corticosteroid, β-interferon and fingolimod. She received alemtuzumab in May 2019 due to increased relapse rates. After the first dose of alemtuzumab, she could not continue her treatment program due to the COVID-19 pandemic. Thyrotoxic thyroid functions (TSH: <0.015 uIU/mL, free T4: 24.79 pmol/L) were detected in the laboratory examination of the patient who was admitted to the endocrinology outpatient clinic with the complaint of palpitation in April 2021. The review of the patient's past laboratory test results determined she was euthyroid before alemtuzumab treatment. She had no personal or family history of thyroid disease. She had no signs and symptoms of thyroid ophthalmopathy. Ultrasonographic examination of her thyroid gland revealed normal size gland and pseudonodular appearance in the parenchyma. Subsequent thyroid scintigraphy showed diffuse uptake of the radioisotope and reduced counting time of the examination. These results were consistent with Graves’ disease. The patient was started on 5 mg methimazole twice a day. Since the etiology of Graves’ disease was thought to be primarily related to alemtuzumab, the patient's MS treatment was continued with ocrelizumab. She stopped the methimazole treatment within 3 months and did not regularly show up to her follow-up visit. In November 2022, she was admitted to the outpatient department with palpitation, sweating, and irritability symptoms. Thyrotoxic thyroid functions were detected again (TSH:<0,015 uIU/mL, free T4: 26,82 pmol/L). She was restarted on 5 mg methimazole treatment twice a day. In June 2023, she was euthyroid (TSH: 0,496 uIU/mL, free T4: 5,42 pmol/L, free T4: 10,45 pmol/L) and her TSI level was undetectable. The methimazole was reduced to 5 mg once a day. She continues to her treatment and follow-up in our center. Conclusion Graves’ disease is a common complication of alemtuzumab use in MS. Alemtuzumab-associated Graves’ disease follows an atypical course compared to the classical form of the disease. The spontaneous remission rate is less than in the classical form of the disease, and medical treatment is often required. Thyroidectomy may be necessary in cases that do not respond to antithyroid agents. Close monitoring of thyroid function tests is essential in alemtuzumab-associated Graves’ disease.

Mechanism Exploration on the Immunoregulation of Allogeneic Heart Transplantation Rejection in Rats With Exosome miRNA and Proteins From Overexpressed IDO1 BMSCs.

Immunoregulation and indoleamine 2,3-dioxygenase 1 (IDO1) play pivotal roles in the rejection of allogeneic organ transplantation. This study aims to elucidate the immune-related functional mechanisms of exosomes (Exos) derived from bone marrow-derived mesenchymal stem cells (BMSCs) overexpressing IDO1 in the context of allogeneic heart transplantation (HTx) rejection. A rat model of allogeneic HTx was established. Exos were extracted after transfection with oe-IDO1 and oe-NC from rat BMSCs. Exos were administered via the caudal vein for treatment. The survival of rats was analyzed, and reverse transcription qualitative PCR (RT-qPCR) and immunohistochemistry (IHC) were employed to detect the expression of related genes. Histopathological examination was conducted using hematoxylin and eosin (HE) staining, and flow cytometry was utilized to analyze T-cell apoptosis. Proteomics and RNA-seq analyses were performed on Exos. The data were subjected to functional enrichment analysis using the R language. A protein interaction network was constructed using the STRING database, and miRWalk, TargetScan, and miRDB databases predicted the target genes, differentially expressed miRNAs, and transcription factors (TFs). Exos from BMSCs overexpressing IDO1 prolonged the survival time of rats undergoing allogeneic HTx. These Exos reduced inflammatory cell infiltration, mitigated myocardial damage, induced CD4 T-cell apoptosis, and alleviated transplantation rejection. The correlation between Exos from BMSCs overexpressing IDO1 and immune regulation was profound. Notably, 13 immune-related differential proteins (Anxa1, Anxa2, C3, Ctsb, Hp, Il1rap, Ntn1, Ptx3, Thbs1, Hspa1b, Vegfc, Dcn, and Ptpn11) and 10 significantly different miRNAs were identified. Finally, six key immune proteins related to IDO1 were identified through common enrichment pathways, including Thbs1, Dcn, Ptpn11, Hspa1b, Il1rap, and Vegfc. Thirteen TFs of IDO1-related key miRNAs were obtained, and a TF-miRNA-mRNA-proteins regulatory network was constructed. Exosome miRNA derived from BMSCs overexpressing IDO1 may influence T-cell activation and regulate HTx rejection by interacting with mRNA.

A real-world disproportionality analysis of cyclosporine from the FDA Adverse Event Reporting System (FAERS) database.

Cyclosporine is an immunosuppressant used to prevent organ rejection in kidney, liver, and heart allogeneic transplants. This study aimed to assess the safety of cyclosporine through the analysis of adverse events (AEs) related to cyclosporine in the US Food and Drug Administration Adverse Event Reporting System (FAERS). To detect AEs associated with cyclosporine, a pharmacovigilance analysis was conducted using four algorithms on the FAERS database: reporting odds ratio (ROR), proportional reporting ratio (PRR), Bayesian confidence propagation neural network (BCPNN), and empirical Bayes geometric mean (EBGM). A statistical analysis was performed on data extracted from the FAERS database, covering 19,582 case reports spanning from 2013 to 2022. Among these cases, 3,911 AEs were identified, with 476 linked to cyclosporine as the primary suspected drug. Cyclosporin-induced AEs targeted 27 System Organ Classes (SOCs). Notably, the highest case at the SOC level included eye disorders, injury, poisoning, and procedural complications, as well as immune system disorders, all of which are listed on the cyclosporine label. Furthermore, we discovered novel potential AEs associated with hepatobiliary disorders, among others. Moreover, unexpected adverse drug reactions (ADRs), such as biliary anastomosis complication and spermatozoa progressive motility decrease, were identified. Importantly, these newly identified ADRs were not mentioned on the cyclosporine label, which were involved in injury, poisoning, and procedural complications, and investigations at the SOC level. The study used pharmacovigilance analysis of FAERS database to identify new and unexpected potential ADRs relating to cyclosporine, which can provide safety tips for the safe use of cyclosporine.

Comparison of emulsion and spray methods for fabrication of rapamycin-loaded acetalated dextran microparticles.

Rapamycin (rapa), an immunosuppressive medication, has demonstrated considerable effectiveness in reducing organ transplant rejection and treating select autoimmune diseases. However, the standard oral administration of rapa results in poor bioavailability, broad biodistribution, and harmful off-target effects, necessitating improved drug delivery formulations. Polymeric microparticles (MPs) are one such solution and have demonstrated promise in pre-clinical studies to improve the therapeutic efficacy of rapa. Nevertheless, MP formulations are highly diverse, and fabrication method selection is a critical consideration in formulation design. Herein, we compared common fabrication processes for the development of rapa-loaded MPs. Using the biopolymer acetalated dextran (Ace-DEX), rapa-loaded MPs were fabricated by both emulsion (homogenization and sonication) and spray (electrospray and spray drying) methods, and resultant MPs were characterized for size, morphology, surface charge, and drug release kinetics. MPs were then screened in LPS-stimulated macrophages to gauge immunosuppressive efficacy relative to soluble drug. We determined that homogenized MPs possessed the most optimal combination of sizing, tunable drug release kinetics, and immunosuppressive efficacy, and we subsequently demonstrated that these characteristics were maintained across a range of potential rapa loadings. Further, we performed in vivo trafficking studies to evaluate depot kinetics and cellular uptake at the injection site after subcutaneous injection of homogenized MPs. We observed preferential MP uptake by dendritic cells at the depot, highlighting the potential for MPs to direct more targeted drug delivery. Our results emphasize the significance of fabrication method in modulating the efficacy of MP systems and inform improved formulation design for the delivery of rapa.

A comprehensive survey of Mn(I) carbonyls as CO-releasing molecules reported over the last two decades.

Over the last two decades, manganese(I) carbonyl complexes have been widely investigated as carbon monoxide releasing molecules (CORMs) to transfer small quantities of CO to biological targets to have beneficial impacts such as preventing ischemia reperfusion injury and reducing organ transplant rejection. Furthermore, these complexes exhibit beneficial anti-coagulative, anti-apoptotic, anti-inflammatory, and anti-proliferative properties. Owing to their highly controlled substitution chemistry and oxidative durability, Mn(I) carbonyl moieties were combined with a wide range of auxiliary ligands, including biomolecules. This review focused on tri- and tetracarbonyl Mn(I) complexes that were exposed to light, changed the redox status, or underwent thermal activation to release carbon monoxide. Kinetic parameters, stability in the dark, number of CO release equivalents, CO detection tools, and the nature of solvents used in the studies are reported and tabulated. An overview of all the previously published Mn(I) CORMs is specifically provided to define the method of action of these promising biologically active compounds and discuss their possible therapeutic applications in relation to their CO-releasing and biocompatibility characteristics.

Dysregulation of Lymphatic Endothelial VEGFR3 Signaling in Disease.

Vascular endothelial growth factor (VEGF) receptor 3 (VEGFR3), a receptor tyrosine kinase encoded by the FLT4 gene, plays a significant role in the morphogenesis and maintenance of lymphatic vessels. Under both normal and pathologic conditions, VEGF-C and VEGF-D bind VEGFR3 on the surface of lymphatic endothelial cells (LECs) and induce lymphatic proliferation, migration, and survival by activating intracellular PI3K-Akt and MAPK-ERK signaling pathways. Impaired lymphatic function and VEGFR3 signaling has been linked with a myriad of commonly encountered clinical conditions. This review provides a brief overview of intracellular VEGFR3 signaling in LECs and explores examples of dysregulated VEGFR3 signaling in various disease states, including (1) lymphedema, (2) tumor growth and metastasis, (3) obesity and metabolic syndrome, (4) organ transplant rejection, and (5) autoimmune disorders. A more complete understanding of the molecular mechanisms underlying the lymphatic pathology of each disease will allow for the development of novel strategies to treat these chronic and often debilitating illnesses.

A New Hypothesis Describing the Pathogenesis of Oral Mucosal Injury Associated with the Mammalian Target of Rapamycin (mTOR) Inhibitors.

It has been 24 years since rapamycin (sirolimus) was approved to mitigate solid organ transplant rejection and 16 years since mTOR (mammalian/mechanistic target of rapamycin) inhibitors reached patients as a cancer therapy. While the clinical benefits of mTOR inhibitors (mTORi) are robust, so too are their toxicities. Among the most common issues is the development of ulcers of the oral mucosa (mTOR-inhibitor associated stomatitis; mIAS). These lesions are distinct from those of other anti-cancer agents, occur with regularity, and impact patient outcomes. mIAS' pathogenesis has been the subject of speculation, and its similar presentation to recurrent aphthous stomatitis (RAS) has led to the hypothesis that it might serve as a surrogate to better understand RAS. Based on a review of the literature, the current manuscript provides a hypothesis regarding the mechanisms by which mTORis uniquely initiate mucosal injury and an explanation for the observation that steroids (also an immunosuppressive) are effective in its treatment through a non-immunologic mechanism. Unexplained unique features of mIAS are discussed in this review in the context of future investigation.

Blockade of Common Gamma Chain Cytokine Signaling with REGN7257, an Interleukin 2 Receptor Gamma (IL2RG) Monoclonal Antibody, in Combination with Costimulatory Blockers Delayed Skin Graft Rejection in Mice

There is a current medical need to identify innovative maintenance therapies to prevent allograft rejection in solid organ transplantation. During transplant rejection, recipient immune cells identify a grafted organ as foreign and attack it: CD4 + T cells orchestrate transplant rejection by recruiting a range of effector cells responsible for the damage of rejection including CD8 + T cells, NK cells, B cells and macrophages. These pathogenic immune cell responses can be driven by cytokines of the common gamma chain (γ c) cytokine family (IL2, IL4, IL7, IL9, IL15, and IL21). γ c cytokines signal through their corresponding receptors, expressed primarily on immune cells, that share a common coreceptor, interleukin 2 receptor subunit gamma (IL2RG) that is required for signaling. To understand the role of γ c cytokines in driving transplant rejection, we generated REGN7257, a fully human IL2RG monoclonal antibody that inhibits γ c cytokine-induced signaling, and we tested its ability to suppress allogeneic immune cell responses in a mouse model of skin graft rejection when delivered as a monotherapy and in combination with mycophenolate mofetil (MMF) or T cell costimulatory pathway blockers. In this model, recipient B6/129 (mixed background) Il2rg hu/hu mice were transplanted with tail skin from BALB/cJ donor mice. Graft survival was analyzed using a log rank Mantel-Cox test to detect statistically significant differences across groups (*=p<0.033; **= p<0.002; ***=p<0.0002; ****=p<0.0001). In a mouse model of skin graft rejection, γ c cytokine signaling blockade with REGN7257 given as maintenance immunosuppression effectively improved overall graft survival (Median Survival Time [MST] IL2RG=13) compared to mice that received a control antibody (MST CTRL=9 [****vs IL2RG Ab]), and with similar efficacy to that observed with the calcineurin inhibitor tacrolimus (MST TAC=12.5 [**vs control, n.s. vs IL2RG Ab]). In treatment combination experiments, while monotherapy treatment with the antiproliferative agent MMF was not as efficient as REGN7257 at delaying skin graft rejection (MST MMF=10 [*vs control] and MST IL2RG=12 [*vs MMF]), simultaneous blockade of cell proliferation and γ c cytokine signaling conferred an advantage over monotherapies (MST MMF+IL2RG=15.5 [****vs control, **vs IL2RG Ab]). Similarly, induction therapy consisting of γ c cytokine signaling blockade followed by maintenance immunosuppression using the CTLA4-Ig fusion protein abatacept, significantly improved overall skin graft survival (MST IL2RG+CTLA4=19.5 [****vs control]) compared to REGN7257 induction only (MST IL2RG=11 [****vs control and combo]) or abatacept maintenance only (MST CTLA4=10 [*vs control, ****vs combo]). Finally, maintenance immunosuppression combining blocking of γc cytokine signaling together with blocking of both CD28 and CD40L costimulatory signals prolonged skin graft survival better than any combination therapies of only 2 pathway blockers (MST TRIPLE=26 [**vs control] and MST DOUBLE=16-21 [n.s.-** vs triple]). Overall, our study showed that γ c cytokine blockade could potentially be an alternative to calcineurin inhibitor-based regimens to prevent rejection by specifically targeting immune cells. Our data also highlighted the inherent complexity of effector mechanisms and pathways involved in allograft rejection and showed that prolonged allograft survival requires simultaneous blockade of multiple T cell activating signals, including inhibition of cytokine signaling and costimulatory signals. These data provide evidence of γ c cytokines as key drivers of allogeneic immune cell responses during acute transplant rejection, offering a potentially novel strategy for the management of transplant patients.

2740. Letermovir for the Prevention and Treatment of Cytomegalovirus Infection in Solid Organ Transplant Recipients

Abstract Background Cytomegalovirus (CMV) is a common infection that can lead to end-organ damage and graft rejection in solid organ transplant (SOT) recipients. Due to the increase in drug-resistant CMV and unfavorable side effect profile of available CMV-active agents, there is a need for additional prophylactic and treatment strategies in this patient population. The goal of this study is to evaluate SOT recipients prescribed letermovir for prophylaxis and/or treatment of CMV. Methods This study was a retrospective review of adult SOT recipients in the Cleveland Clinic Health System prescribed letermovir from 11/8/2017 to 8/1/2022. The primary objective was to describe the utilization of letermovir in SOT recipients. Secondary objectives included: proportion of SOT recipients that experienced CMV breakthrough on letermovir prophylaxis, proportion of SOT recipients that experienced refractory CMV infection on letermovir treatment, prevalence of letermovir resistance, and letermovir-induced adverse effects. Results A total of 45 patients were included in the study, with 52 letermovir courses. Lung was the most commonly transplanted organ (35%), followed by kidney (22%). 78% of patients were high-risk CMV and the most common immunosuppression regimen consisted of a calcineurin inhibitor in combination with a corticosteroid (82%). 11 patients received letermovir for primary CMV prophylaxis, with only one patient experiencing new/worsening viremia while on the agent. Of the 34 patients who received letermovir for secondary CMV prophylaxis, 11 experienced new/worsening viremia. 7 patients received letermovir for CMV treatment, at a median viral load of 991 IU/mL (IQR 603-2,738) on initiation and peak viral load of 3,892 IU/mL (IQR 1,407-10,209) while on therapy. No patients in the treatment group experienced refractory infection. 7/52 (13.5%) letermovir courses were discontinued due to new/worsening viremia, with no letermovir resistance identified. No letermovir-related adverse effects were documented. Conclusion Our study shows that letermovir appears to be effective in suppressing CMV viremia. Letermovir may be an alternative option for SOT recipients who are unable to tolerate or have resistance to traditional CMV therapeutics. Disclosures All Authors: No reported disclosures

Circular RNA MAP2K2-modified immunosuppressive dendritic cells for preventing alloimmune rejection in organ transplantation.

Long-term patient and graft survival has been achieved in organ transplantation but at the expense of toxic side effects that are associated with long-term use of nonspecific immunosuppressive drugs. Discovering new regulators of dendritic cells is the key for development of an ideal treatment to prevent immune rejection. We hypothesized that knockdown of circMAP2K2 induces immunosuppressive DCs and that treatment with circMAP2K2 silenced-DCs can prevent alloimmune rejection. DCs were cultured and transfected with siRNA for circMAP2K2. circMAP2K2 levels were measured by qRT-PCR. DC's maturation and immune function were assessed by flow cytometry and mixed lymphocyte reactions. The function of circMAP2K2 was illustrated by a series of RIP and IP. The therapeutics of engineered DCs was tested in a mouse heart transplantation model. We found that circMAP2K2 was highly expressed in mature DCs. Knockdown of circMAP2K2 reduced expression of MHCII, CD40 and CD80, attenuated the ability of DCs to activate allogeneic naïve T cells, and enhanced CD4+CD25+FOXP3+ regulatory T cells (Treg). circMAP2K2-induced immunosuppressive DCs by interacting with SENP3. Treatment with circMAP2K2-knockdown DCs attenuated alloimmune rejection and prolonged allograft survival in a murine heart transplantation model. The immune suppression induced in vivo was donor-antigen specific. In conclusion, knockdown of circMAP2K2 can induce immunosuppressive DCs which are able to inhibit overactive immune response, highlighting a new promising therapeutic approach for immune disorder diseases.

Temsirolimus is a promising immunomodulatory agent for enhanced transplantation outcomes

BackgroundIdentifying effective immunosuppressive strategies is critical for addressing immunological rejection following organ transplantation. This study explores the potential immunosuppressive effects and mechanisms of temsirolimus, a rapamycin derivative, in organ transplantation. MethodsA mouse cardiac allograft model was established using a cervical cannula technique with BALB/c donors and C57BL/6 recipients. Mice were administered temsirolimus intragastrically and graft survival was evaluated. Histological staining was used to assess pathological changes. The BrdU assay was used to measure splenic T cell proliferation. Flow cytometry was used to quantify regulatory T cells (Tregs), CD4+ T cells, and CD8+ T cells. ELISA and qPCR assays were used to determine Foxp3, IL-4, IFN-γ, and TGF-β expression. ResultsTemsirolimus displayed potent immunosuppressive effects at 20 mg/kg/day, significantly inhibiting T cell proliferation (84.6%, P < 0.0001) and prolonging graft survival (median 49 days vs. 8.5 days in controls, P < 0.0001). However, median survival decreased to 34.5 days upon withdrawal. Temsirolimus also reduced splenic CD4+ and CD8+ T cells (2.85% and 2.92%, P < 0.001) and antibody levels (IgM, IgG1, IgG2) by 11.85–29.09% (P < 0.0001) and increased Tregs, Foxp3, IL-4 (P < 0.01), and TGF-β (P < 0.05), while decreasing IFN-γ (P < 0.001). ConclusionsTemsirolimus exhibited potent immunosuppressive effects, emerging as a strong candidate to mitigate organ transplant rejection.

Circulating T cell specific extracellular vesicle profiles in cardiac allograft acute cellular rejection

There is a critical need for biomarkers of acute cellular rejection (ACR) in organ transplantation. We hypothesized that ACR leads to changes in donor-reactive T cell small extracellular vesicle (sEV) profiles in transplant recipient circulation that match the kinetics of alloreactive T cell activation. In rodent heart transplantation, circulating T cell sEV quantities (P < .0001) and their protein and mRNA cargoes showed time-specific expression of alloreactive and regulatory markers heralding early ACR in allogeneic transplant recipients but not in syngeneic transplant recipients. Next generation sequencing of their microRNA cargoes identified novel candidate biomarkers of ACR, which were validated by stem loop quantitative reverse transcription polymerase chain reaction (n = 10). Circulating T cell sEVs enriched from allogeneic transplant recipients mediated targeted cytotoxicity of donor cardiomyocytes by apoptosis assay (P < .0001). Translation of the concept and EV methodologies to clinical heart transplantation demonstrated similar upregulation of circulating T cell sEV profiles at time points of grade 2 ACR (n = 3 patients). Furthermore, T cell receptor sequencing of T cell sEV mRNA cargo demonstrated expression of T cell clones with intact complementarity determining region 3 signals. These data support the diagnostic potential of T cell sEVs as noninvasive biomarker of ACR and suggest their potential functional roles.

Experiences and Psychological Impact Derived from Unwanted Exposure to Online Pornography in Spanish Adolescents

Abstract Introduction Unwanted exposure (UE) to sexual content may have important consequences on children/adolescents’ psychosexual development. Our objective was to analyze UE to online pornography, parental filter use, type of sexual contents seen, emotional/behavioral reactions, and UE as positive/traumatic experience in Spanish adolescents and to examine these experiences and reactions depending on the type of sexual content. Methods In 2020, 500 Spanish teenagers (13–18 years) completed an ad hoc questionnaire for the evaluation of different dimensions involved in UE to sexual contents, such as those mentioned in the study objectives. Results A high frequency of UE (88.2%) is observed. Regarding the kind of scenes, naked people, straight porn, and people showing genitals are the most unexpectedly seen. Adolescents used to react to the UE closing the window and deleting sexual materials. A greater predominance of negative emotions was revealed, and another noteworthy result is related to the role played by type of sexual content and gender. Gay scenes and being woman increased the probability of living the experience as non-positive, and being woman and viewing naked people/BDSM scenes/under-age sex were associated with reactions of rejection. Conclusions This study contributes significantly to the knowledge of UE to online pornography in adolescents. It provides valuable information about the role played by the type of sexual content seen and the gender in the diverse reactions/experiences derived from the UE to pornography. Policy Implications This topic, that is, involuntary exposure to online sexual material in adolescents, should be included in affective-sexual education and prevention programs at early ages, so that children/adolescents are already trained in healthy sexuality when facing this type of content for the first time. These programs, adjusted to the reality of our adolescents, will minimize the negative impact that UE may have on their psychosexual development.

Vaccination Recommendations in Solid Organ Transplant Adult Candidates and Recipients.

Prevention of infections is crucial in solid organ transplant (SOT) candidates and recipients. These patients are exposed to an increased infectious risk due to previous organ insufficiency and to pharmacologic immunosuppression. Besides infectious-related morbidity and mortality, this vulnerable group of patients is also exposed to the risk of acute decompensation and organ rejection or failure in the pre- and post-transplant period, respectively, since antimicrobial treatments are less effective than in the immunocompetent patients. Vaccination represents a major preventive measure against specific infectious risks in this population but as responses to vaccines are reduced, especially in the early post-transplant period or after treatment for rejection, an optimal vaccination status should be obtained prior to transplantation whenever possible. This review reports the currently available data on the indications and protocols of vaccination in SOT adult candidates and recipients.

Allosteric inhibition of the T cell receptor by a designed membrane ligand.

The T cell receptor (TCR) is a complex molecular machine that directs the activation of T cells, allowing the immune system to fight pathogens and cancer cells. Despite decades of investigation, the molecular mechanism of TCR activation is still controversial. One of the leading activation hypotheses is the allosteric model. This model posits that binding of pMHC at the extracellular domain triggers a dynamic change in the transmembrane (TM) domain of the TCR subunits, which leads to signaling at the cytoplasmic side. We sought to test this hypothesis by creating a TM ligand for TCR. Previously we described a method to create a soluble peptide capable of inserting into membranes and binding to the TM domain of the receptor tyrosine kinase EphA2 (Alves et al., eLife, 2018). Here, we show that the approach is generalizable to complex membrane receptors, by designing a TM ligand for TCR. We observed that the designed peptide caused a reduction of Lck phosphorylation of TCR at the CD3ζ subunit in T cells. As a result, in the presence of this peptide inhibitor of TCR (PITCR), the proximal signaling cascade downstream of TCR activation was significantly dampened. Co-localization and co-immunoprecipitation in diisobutylene maleic acid (DIBMA) native nanodiscs confirmed that PITCR was able to bind to the TCR. AlphaFold-Multimer predicted that PITCR binds to the TM region of TCR, where it interacts with the two CD3ζ subunits. Our results additionally indicate that PITCR disrupts the allosteric changes in the compactness of the TM bundle that occur upon TCR activation, lending support to the allosteric TCR activation model. The TCR inhibition achieved by PITCR might be useful to treat inflammatory and autoimmune diseases and to prevent organ transplant rejection, as in these conditions aberrant activation of TCR contributes to disease.

Total Lymphoid Irradiation in the Treatment of Heart Transplant Rejection: Single Institution Long-Term Results

Acute cardiac allograft rejection is a major cause of morbidity and mortality post-transplant. Total lymphoid irradiation (TLI) has been shown to cause long-lasting alterations in lymphocyte sub-sets, and thereby induces a state of partial response that is useful to prevent organ transplant rejection. In our previous report, treatment with TLI resulted in decreased episodes of acute rejection and steroid dosage requirements for up to 9.1 years post cardiac transplantation. In this study, we report an update on the short- and long-term effects of TLI in the treatment of cardiac transplant rejection. We performed a retrospective analysis of patients with intractable cardiac allograft transplantation evaluated in the department of radiation oncology at our institution over 23 years (1998-2021). Cardiac allograft rejection was defined as multiple or persistent episodes of rejection despite aggressive immunosuppressive therapy. The prescribed dose was 8 Gy in 10 fractions to be delivered over 5 weeks. All episodes of pathologic acute cardiac rejection, duration of immunosuppression, and episodes of acute infection requiring treatment before and after TLI were documented. Overall survival (OS) was analyzed using Kaplan-Meier method. The median time to first cardiac allograft rejection and the median time to first acute rejection was monitored. Of the 29 patients included, 21 (72.4%) had ISHLT grade 1R, 5 (17.2%), grade 2R, and 2(6.9%) grade 3R rejection. Rejection grade was unknown for 1 patient. The mean number of acute rejections after transplant was 14.4 episodes per patient (range 1-44) with median time to first rejection of 0.63 months. The median radiation dose was 8 Gy (range 7.2-8 Gy) delivered over a mean of 31 days. Treatment was stopped early in 2 (6.5%) patients (after 7.2 Gy and 7.9 Gy) for severe bone marrow suppression and drop in CD4 counts, respectively. The number of rejections dropped from 14.2 to 3.97 per patient over a median time of 29.0 months vs 28.1 months pre and post TLI (p = 0.01). The frequency of ISHLT acute grade 3R rejections decreased from 0.58 to 0.06 episodes per patient pre and post TLI (p = 0.02). Immunosuppressant requirements decreased from 2.83 before TLI to 2.69 after TLI (p = 0.71). Infection rates per patient were 0.71 pre TLI and remained at 0.63 post TLI. Treatment was well tolerated with 4 (13.8%) grade 2 or higher radiation toxicity. Median follow up was 76.3 months. Median and 3-year OS were 53.4 months and 60.9%, respectively. TLI is a safe and effective treatment for control of intractable cardiac rejection. The episodes of acute rejection and immunosuppressant requirements are decreased, but with long-term follow up, these patients continue to experience rejection. However, TLI lowers the frequency of ISHLT moderate to severe rejection episodes for up to 6.4 years. There was no increased risk of severe infections and there were only minimal short- and long-term grade 2 or higher radiation toxicities.

Comparison of the effects of mycophenolate mofetil alone and with testosterone on sperm, sex hormones and antioxidant enzymes in male rats

Background: Mycophenolate mofetil (MMF) is an immunosuppressant drug which is used to inhibit organ transplant rejection and to treat autoimmune diseases. Theoretically, such medications have spermatotoxic and genotoxic effects. However, evidence on the effects of MMF on fertility is limited and controversial.This study evaluated the effects of MMF and testosterone on sperm, sex hormones and antioxidant enzymes in male rats. Materials and Methods: In this experimental study 24 adult male Naval Medical Research Institute (NMRI) mice randomly divided into 3 groups: 1- saline serum (control), 2- MMF and 3- MMF along with testosterone by subcutaneous injection, for 65 days. Change in body weight, sperm quality (concentration, motility and morphology), serum level of gonadotropin hormones, and testosterone, superoxide dismutase (SOD), glutathione (GSH), catalase, total antioxidant capacity (TAC) in serum and epididymis were evaluated. Findings: Both MMF treatment groups compared to control showed a decrease in body weight, number and motility of sperm, level of testosterone, antioxidant enzymes (SOD, GSH, and catalase) and TAC (P&lt;0.05), and increase of gonadotropin hormones and sperm morphology abnormality (P&lt;0.05). The adverse effects on sperm count and epididymis testosterone levels in the Mycophenolatemofetil +testosterone group was less than the Mycophenolate mofetil group (P&lt;0.05). Conclusion: This study showed that Mycophenolatemofetil has adverse effects on sperm count, gonadotropins , testosterone and antioxidant pathway enzymes, and the use of testosterone cannot reduce the adverse effects of MMF. The adverse effects of Mycophenolate mofetil may be due to a decrease in the level of antioxidants.

Implantable bioelectronic systems for early detection of kidney transplant rejection.

Early-stage organ transplant rejection can be difficult to detect. Percutaneous biopsies occur infrequently and are risky, and measuring biomarker levels in blood can lead to false-negative and -positive outcomes. We developed an implantable bioelectronic system capable of continuous, real-time, long-term monitoring of the local temperature and thermal conductivity of a kidney for detecting inflammatory processes associated with graft rejection, as demonstrated in rat models. The system detects ultradian rhythms, disruption of the circadian cycle, and/or a rise in kidney temperature. These provide warning signs of acute kidney transplant rejection that precede changes in blood serum creatinine/urea nitrogen by 2 to 3 weeks and approximately 3 days for cases of discontinued and absent administration of immunosuppressive therapy, respectively.