A transcriptionally distinct subset of influenza-specific effector memory B cells predicts long-lived antibody responses to vaccination in humans.

Seasonal influenza vaccination elicits hemagglutinin (HA)-specific memory B (Bmem) cells, and although multiple Bmem cell populations have been characterized, considerable heterogeneity exists. We found that HA-specific human Bmem cells differed in the expression of surface marker FcRL5 and transcriptional factor T-bet. FcRL5+T-bet+ Bmem cells were transcriptionally similar to effector-like memory cells, while T-betnegFcRL5neg Bmem cells exhibited stem-like central memory properties. FcRL5+ Bmem cells did not express plasma-cell-commitment factors but did express transcriptional, epigenetic, metabolic, and functional programs that poised these cells for antibody production. Accordingly, HA+ T-bet+ Bmem cells at day 7 post-vaccination expressed intracellular immunoglobulin, and tonsil-derived FcRL5+ Bmem cells differentiated more rapidly into antibody-secreting cells (ASCs) in vitro. The T-bet+ Bmem cell response positively correlated with long-lived humoral immunity, and clonotypes from T-bet+ Bmem cells were represented in the secondary ASC response to repeat vaccination, suggesting that this effector-like population predicts influenza vaccine durability and recall potential.

A multicenter prospective study to define the natural history of BK viral infections in kidney transplantation.

BACKGROUND: BK polyomavirus (BKV) can cause permanent loss of allograft function due to BKV-associated nephropathy (BKVN) in kidney transplant recipients. Besides immunosuppression reduction, there are no consistently effective interventions for BKV infection. Study purpose was to define natural history of BKV infection, identify risk factors for BKV reactivation and BKVN in kidney transplant recipients, and inform the design/conduct of future clinical trials of BKV-targeted therapeutics. METHODS: We conducted a multicenter prospective observational study of incident kidney transplant recipients at six U.S. transplant centers. Participants were monitored every 4 weeks for BKV reactivation and followed for up to 24 months post-transplant. We used regression models (logistic, survival, mixed models) to study relationships between BK viremia/BKVN, clinical characteristics, and allograft function. RESULTS: We enrolled 335 participants. Fifty-eight (17%) developed BK viremia, 6 (2%) developed biopsy-proven BKVN, and 29 (9%) developed suspected/presumed BKVN (defined as BKV viral load > 10,000 copies/mL without biopsy). Male donor sex was associated with lower odds for BK viremia, whereas recipient Black race was associated with two-fold increased odds for BK viremia. Recipient female sex was associated with more rapid clearance of BK viremia. Persistent BK viremia/BKVN was associated with poorer allograft function by 24 months post-transplant. CONCLUSIONS: We identified multiple donor and recipient demographic factors associated with risk for BKV infection and poorer allograft function by 24 months post-transplant. This may help design future clinical trials of therapies to prevent or mitigate the deleterious impact of BKV reactivation on kidney transplant outcomes.

Infection and clinical xenotransplantation: Guidance from the Infectious Disease Community of Practice of the American Society of Transplantation.

This guidance was developed to summarize current approaches to the potential transmission of swine-derived organisms to xenograft recipients, health care providers, or the public in clinical xenotransplantation. Limited specific data are available on the zoonotic potential of pig pathogens. It is anticipated that the risk of zoonotic infection in xenograft recipients will be determined by organisms present in source animals and relate to the nature and intensity of the immunosuppression used to maintain xenograft function. Based on experience in allotransplantation and with preclinical models, viral infections are of greatest concern, including porcine cytomegalovirus, porcine lymphotropic herpesvirus, and porcine endogenous retroviruses. Sensitive and specific microbiological assays are required for routine microbiological surveillance of source animals and xenograft recipients. Archiving of blood samples from recipients, contacts, and hospital staff may provide a basis for microbiological investigations if infectious syndromes develop. Carefully implemented infection control practices are required to prevent zoonotic pathogen exposures by clinical care providers. Informed consent practices for recipients and their close contacts must convey the lack of specific data for infectious risk assessment. Available data suggest that infectious risks of xenotransplantation are manageable and that clinical trials can advance with carefully developed protocols for pretransplant assessment, syndrome evaluation, and microbiological monitoring.

Recommendations on prevention of infections during chimeric antigen receptor T-cell and bispecific antibody therapy in multiple myeloma.

Chimeric antigen receptor T (CAR T) cell and bispecific antibody therapies have shown unprecedented efficacy in heavily pretreated patients with multiple myeloma (MM). However, their use is associated with a significant risk of severe infections, which can be attributed to various factors such as hypogammaglobulinemia, neutropenia, lymphopenia, T-cell exhaustion, cytokine-release syndrome and immune-effector cell-associated neurotoxicity syndrome. As these therapies have been recently approved by regulatory agencies, it is crucial to establish practical guidelines for infection monitoring and prevention until robust data from prospective clinical trials become available. To address this issue, a panel of experienced investigators from the Academic Consortium to Overcome Multiple Myeloma through Innovative Trials (COMMIT) developed consensus recommendations for mitigating infections associated with CAR T-cell and bispecific antibody therapies in MM patients.

COVID-19 Vaccination and Remdesivir are Associated With Protection From New or Increased Levels of Donor-Specific Antibodies Among Kidney Transplant Recipients Hospitalized With COVID-19.

Alloimmune responses in kidney transplant (KT) patients previously hospitalized with COVID-19 are understudied. We analyzed a cohort of 112 kidney transplant recipients who were hospitalized following a positive SARS-CoV-2 test result during the first 20 months of the COVID-19 pandemic. We found a cumulative incidence of 17% for the development of new donor-specific antibodies (DSA) or increased levels of pre-existing DSA in hospitalized SARS-CoV-2-infected KT patients. This risk extended 8 months post-infection. These changes in DSA status were associated with late allograft dysfunction. Risk factors for new or increased DSA responses in this KT patient cohort included the presence of circulating DSA pre-COVID-19 diagnosis and time post-transplantation. COVID-19 vaccination prior to infection and remdesivir administration during infection were each associated with decreased likelihood of developing a new or increased DSA response. These data show that new or enhanced DSA responses frequently occur among KT patients requiring admission with COVID-19 and suggest that surveillance, vaccination, and antiviral therapies may be important tools to prevent alloimmunity in these individuals.

Moving xenotransplantation from bench to bedside: Managing infectious risk.

Xenotransplantation of organs from swine in immunosuppressed human recipients poses many of the same challenges of allotransplantation relative to the risk for infection, malignancy, or graft rejection in proportion to the degree of immunosuppression and epidemiologic exposures. The unique features of xenotransplantation from pigs relative to infectious risk center on the potential for unusual organisms derived from swine causing productive infection, "xenosis" or "xenozoonosis," in the host. Based on experience in allotransplantation, the greatest hazard is due to viruses, due to the relative lack of information regarding the behavior of these potential pathogens in humans, the absence of validated serologic and molecular assays for swine-derived pathogens, and uncertainty regarding the efficacy of therapeutic agents for these organisms. Other known, potential pathogens (i.e., bacteria, fungi, parasites) tend to be comparable to those of humans. Concerns remain for unknown organisms in swine that may replicate in immunosuppressed humans. Clinical trials of genetically modified organs sourced from swine in immunosuppressed humans with organ failure are under development. Such trials require informed consent regarding potential infectious risks to the recipient, determination of breeding characteristics of swine, assessments of potential risks to the public and healthcare providers, consideration of ethical issues posed by this novel therapy, and defined strategies to monitor and address infectious episodes that may be encountered by healthcare teams. Clinical trials in xenotransplantation will allow improved definition of potential infectious risks.

Immunologic and Infectious Concerns in Uterus Transplantation.

Pharmacologic immunosuppression is required for the success of uterus transplantation but can provoke several complications for the transplant recipient. In this review, we discuss the immunologic complications that can occur in the uterus transplant recipient. First, we provide the latest update on immunosuppression regimens used by programs throughout the world. Next, we discuss the prevalence, mechanisms, treatment, and outcome of rejection in uterus transplant recipients. Finally, we discuss infectious complications of varying severity alongside their treatment and impact.

Vancomycin-resistant Enterococcus in solid organ transplant recipients: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice.

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation address vancomycin-resistant enterococci (VRE) infections in SOT candidates and recipients. VRE are an important cause of infection and have been named by the CDC as a serious public threat. Typically, a commensal of the gastrointestinal tract, VRE may become pathogenic after abdominal organ manipulation like transplantation. This guideline reviews the microbiology, antimicrobial resistance mechanisms, epidemiology, and clinical manifestations of VRE infection in the context of solid organ transplantation. Treatment regimens including combination therapies and novel investigational agents are also reviewed. Finally, an updated appraisal of infection control measures relevant to VRE infection and colonization is presented.

Donor-derived infections and infectious risk in xenotransplantation and allotransplantation.

Post-transplantation infections are common in allograft recipients and should be expected in all immunocompromised hosts. Based on the need for immunosuppression in xenotransplantation, procedures developed to enhance safety in allotransplantation can be applied in future xenotransplantation clinical trials. Standardized approaches can be developed to guide the evaluation of common infectious syndromes in xenograft recipients. The opportunity created by screening of swine intended as xenograft donors has equal applicability to allotransplantation-notably broader screening strategies for allograft donors such as use of advanced sequencing modalities including broad-range molecular probes, microarrays, and high-throughput pyrosequencing. Considerations in management of allotransplant- and xenotransplant-associated infections are largely the same. Experience in xenotransplantation will continue to inform thinking regarding donor-derived infections in allotransplantation. We expect that experience in managing complex allotransplant recipients will similarly inform clinical trials in xenotransplantation.

Moving Career Development Upstream: Evaluation of a Course for Internal Medicine Trainees Contemplating Career Pathways in Academic Medicine.

OBJECTIVES: Despite training in academic medical centers, many residents and fellows lack an understanding of the different career paths in academic medicine. Without this fundamental knowledge, choosing an academic career pathway and transitioning to junior faculty is challenging. We started the Pathways in Academic Medicine course ("Pathways") to introduce residents and fellows to the wide array of academic career pathways and to expose them to the concepts and resources needed to transition successfully from trainee to junior faculty. RESULTS: Sixty-nine medicine residents and fellows participated in Pathways programming. Surveys and focus groups revealed high satisfaction with the course sessions. Trainees indicated that Pathways helped them to envision an academic career, clarified the steps needed to pursue an academic career, and normalized common challenges. CONCLUSIONS: Pathways is an important educational innovation that gives participants experiences to jumpstart successful careers in academic medicine. We hope that our program will serve as an example for other institutions interested in improving the trainee-to-faculty transition.

Two Cases and a Review of Graft-Versus-Host Disease and the Role of Hepatitis C Treatment in Liver Transplant Patients.

Graft-versus-host disease (GvHD) is a rare but fatal complication after solid organ transplantation arising in 1% to 2% of cases. We report 2 cases of GvHD after orthotopic liver transplantation. Both patients had a history of hepatitis C virus (HCV) infection prior to transplantation. Both cases presented between 1 and 4 months after transplantation with rash, pancytopenia, and/or diarrhea. Our second case also developed oral and ocular manifestations after liver transplantation, which are more commonly described after stem cell transplantation. Diagnosis in both cases was made by clinical presentation in conjunction with histopathology and flow cytometry. Both patients were treated by increasing immunosuppression with tacrolimus and high-dose steroids. Response to treatment differed based on the degree of pancytopenia. Our case report is distinguished by several factors such as the context of GvHD presentation and the role of HCV treatment. Diagnosis of GvHD is difficult and often delayed due to nonspecific presentation that overlaps with other conditions. Furthermore, the relation between HCV treatment and potential initiation of GvHD in solid organ transplant patients is unclear.

The Microbiome, Systemic Immune Function, and Allotransplantation.

Diverse effects of the microbiome on solid organ transplantation are beginning to be recognized. In allograft recipients, microbial networks are disrupted by immunosuppression, nosocomial and community-based infectious exposures, antimicrobial therapies, surgery, and immune processes. Shifting microbial patterns, including acute infectious exposures, have dynamic and reciprocal interactions with local and systemic immune systems. Both individual microbial species and microbial networks have central roles in the induction and control of innate and adaptive immune responses, in graft rejection, and in ischemia-reperfusion injury. Understanding the diverse interactions between the microbiome and the immune system of allograft recipients may facilitate clinical management in the future.

Infections after xenotransplantation.

PURPOSE OF REVIEW: Xenotransplantation offers a solution for the global shortage of available organs. However, cross-species transplantation and immunosuppression raises concerns about transmission of zoonotic infections to the recipient as well as to the public. RECENT FINDINGS: Here, we review the major infections of concern after xenotransplantation, risks of their transmission, diagnostic, therapeutic as well as prevention modalities for these infections after xenotransplantation. This review is particularly timely in light of recent advances in porcine genome editing technology that allow removal of retroviral sequences. SUMMARY: We cannot appreciate the full risk of infections after xenotransplantation in absence of clinical trials. However, there are guidelines for strict microbiologic monitoring and reporting, infectious diagnostic assay development, breeding and quarantine of graft source animals to limit infectious transmission.

Rhodococcus Infection in Solid Organ and Hematopoietic Stem Cell Transplant Recipients1.

We conducted a case-control study of 18 US transplant recipients with Rhodococcus infection and 36 matched controls. The predominant types of infection were pneumonia and bacteremia. Diabetes mellitus and recent opportunistic infection were independently associated with disease. Outcomes were generally favorable except for 1 relapse and 1 death.

A National Study of Outcomes among HIV-Infected Kidney Transplant Recipients.

Kidney transplantation is a viable treatment for select patients with HIV and ESRD, but data are lacking regarding long-term outcomes and comparisons with appropriately matched HIV-negative patients. We analyzed data from the Scientific Registry of Transplant Recipients (SRTR; 2002-2011): 510 adult kidney transplant recipients with HIV (median follow-up, 3.8 years) matched 1:10 to HIV-negative controls. Compared with HIV-negative controls, HIV-infected recipients had significantly lower 5-year (75.3% versus 69.2%) and 10-year (54.4% versus 49.8%) post-transplant graft survival (GS) (hazard ratio [HR], 1.37; 95% confidence interval [95% CI], 1.15 to 1.64; P<0.001) that persisted when censoring for death (HR, 1.43; 95% CI, 1.12 to 1.84; P=0.005). However, compared with HIV-negative/hepatitis C virus (HCV)-negative controls, HIV monoinfected recipients had similar 5-year and 10-year GS, whereas HIV/HCV coinfected recipients had worse GS (5-year: 64.0% versus 52.0%, P=0.02; 10-year: 36.2% versus 27.0%, P=0.004 [HR, 1.38; 95% CI, 1.08 to 1.77; P=0.01]). Patient survival (PS) among HIV-infected recipients was 83.5% at 5 years and 51.6% at 10 years and was significantly lower than PS among HIV-negative controls (HR, 1.34; 95% CI, 1.08 to 1.68; P<0.01). However, PS was similar for HIV monoinfected recipients and HIV-negative/HCV-negative controls at both times. HIV/HCV coinfected recipients had worse PS compared with HIV-negative/HCV-infected controls (5-year: 67.0% versus 78.6%, P=0.007; 10-year: 29.3% versus 56.23%, P=0.002 [HR, 1.57; 95% CI, 1.11 to 2.22; P=0.01]). In conclusion, HIV-negative and HIV monoinfected kidney transplant recipients had similar GS and PS, whereas HIV/HCV coinfected recipients had worse outcomes. Although encouraging, these results suggest caution in transplanting coinfected patients.

The cyclin dependent kinase inhibitor (R)-roscovitine mediates selective suppression of alloreactive human T cells but preserves pathogen-specific and leukemia-specific effectors.

Graft versus host disease (GvHD), mediated by donor T cells, remains the primary cause of non-relapse mortality after allogeneic hematopoietic stem cell transplantation and novel therapeutic approaches are required. Cdk2 is a critical node of signal integration and programming of T cell responses towards immunity versus anergy but is dispensable for hematopoiesis and thymocyte development. We examined the effects of pharmacologic Cdk2 inhibition on alloreactive human T cells. Inhibition of Cdk2 blocked expansion of alloreactive T cells upon culture with HLA-mismatched dendritic cells and prevented generation of IFN-γ-producing alloantigen-specific effectors. In contrast, Cdk2 inhibition preserved effectors specific for Wilms' tumor 1 (WT1) leukemia antigen and for CMV as determined by WT1-specific and CMV-specific pentamers. Cdk2 inhibition preserved Treg cells, which have the ability to prevent GvHD while maintaining GvL. Thus, Cdk inhibitors may improve allogeneic HSCT by reducing alloreactivity and GvHD without loss of pathogen-specific and leukemia-specific immunity.

T-bet+ B Cells in Humans: Protective and Pathologic Functions.

The humoral immune system comprises B cells and plasma cells, which play important roles in organ transplantation, ranging from the production of both protective and injurious antibodies as well as cytokines that can promote operational tolerance. Recent data from conditions outside of transplantation have identified a novel human B-cell subset that expresses the transcription factor T-bet and exerts pleiotropic functions by disease state. Here, we review the generation, activation, and functions of the T-bet+ B-cell subset outside of allotransplantation, and consider the relevance of this subset as mediators of allograft injury.

Low molecular weight hyaluronan inhibits lung epithelial ion channels by activating the calcium-sensing receptor.

Herein, we tested the hypothesis that low molecular weight hyaluronan (LMW-HA) inhibits lung epithelial ions transport in-vivo, ex-vivo, and in-vitro by activating the calcium-sensing receptor (CaSR). Twenty-four hours post intranasal instillation of 50-150 µg/ml LMW-HA to C57BL/6 mice, there was a 75% inhibition of alveolar fluid clearance (AFC), a threefold increase in the epithelial lining fluid (ELF) depth, and a 20% increase in lung wet/dry (W/D) ratio. Incubation of human and mouse precision cut lung slices with 150 µg/ml LMW-HA reduced the activity and the open probability (Po) of epithelial sodium channel (ENaC) in alveolar epithelial type 2 (ATII) cells, and in mouse tracheal epithelial cells (MTEC) monolayers as early as 4 h. The Cl- current through cystic fibrosis transmembrane conductance regulator (CFTR) and the activity of Na,K-ATPase were both inhibited by more than 66% at 24 h. The inhibitory effects of LMW-HA on ion channels were reversed by 1 µM NPS-2143, or 150 µg/ml high molecular weight hyaluronan (HMW-HA). In HEK-293 cells expressing the calcium-sensitive Cl- channel TMEM16-A, CaSR was required for the activation of the Cl- current by LMW-HA. This is the first demonstration of lung ions and water transport inhibition by LMW-HA, and its mediation through the activation of CaSR.

Bilateral Lung Transplantation With Donor Positive for COVID-19 Infection on Bronchoalveolar Lavage: A Case Report.

Initial experience with lung transplant of COVID-19-positive donors was marked by disappointing results, including a reported case of mortality through donor to recipient transmission of infection. However, since that time a number of improvements in preventative and therapeutic measures against COVID-19 have been developed. We present the case of a 51-year-old woman with scleroderma-associated interstitial lung disease who was awaiting lung transplant. A potential donor with excellent lung physiology was located; however, initial testing on bronchoalveolar lavage (BAL) was positive for COVID-19. The donor had tested positive 2 weeks prior and had symptomatically recovered. Our patient had been fully vaccinated but not seroconverted. Given the history of a donor with recovering COVID infection and a fully immunized recipient, our multidisciplinary team elected to proceed with the transplant. The patient successfully underwent bilateral lung transplant with standard induction immunosuppression. Bebtelovimab was given post-transplant day 1 because the recipient remained seronegative to COVID-19. Serial bronchoalveolar lavages post transplant have been negative for COVID-19. The patient has done well after transplant. She was seen in the clinic 2 months post transplant and is ambulatory without supplemental oxygen requirements. To our knowledge, this represents the first reported successful case of lung transplant with a donor positive for COVID-19 on lower respiratory tract sampling.