Decline in Estimated Glomerular Filtration Rate After Dapagliflozin in Heart Failure With Mildly Reduced or Preserved Ejection Fraction: A Prespecified Secondary Analysis of the DELIVER Randomized Clinical Trial.

Importance: An initial decline in estimated glomerular filtration rate (eGFR) is expected after initiating a sodium-glucose cotransporter-2 inhibitor (SGLT2i) and has been observed across patients with diabetes, chronic kidney disease, and heart failure. Objective: To examine the implications of initial changes in eGFR among patients with heart failure with mildly reduced ejection fraction (HFmrEF) or preserved ejection fraction (HFpEF) enrolled in the Dapagliflozin Evaluation to Improve the Lives of Patients With Preserved Ejection Fraction Heart Failure (DELIVER) trial. Design, Setting, and Participants: This was a prespecified analysis of the results of the DELIVER randomized clinical trial, which was an international multicenter study of patients with EF greater than 40% and eGFR greater than or equal to 25. The DELIVER trial took place from August 2018 to March 2022. Data for the current prespecified study were analyzed from February to October 2023. Intervention: Dapagliflozin, 10 mg per day, or placebo. Main Outcomes and Measures: In this prespecified analysis, the frequency of an initial eGFR decline (baseline to month 1) was compared between dapagliflozin and placebo. Cox models adjusted for baseline eGFR and established prognostic factors were fit to estimate the association of an initial eGFR decline with cardiovascular (cardiovascular death or heart failure event) and kidney (≥50% eGFR decline, eGFR<15 or dialysis, death from kidney causes) outcomes, landmarked at month 1, stratified by diabetes. Results: Study data from 5788 participants (mean [SD] age, 72 [10] years; 3253 male [56%]) were analyzed. The median (IQR) change in eGFR level from baseline to month 1 was -1 (-6 to 5) with placebo and -4 (-9 to 1) with dapagliflozin (difference, -3; P < .001). A higher proportion of patients assigned to dapagliflozin developed an initial eGFR decline greater than 10% vs placebo (1144 of 2892 [40%] vs 737 of 2896 [25%]; odds ratio, 1.9; 95% CI, 1.7-2.1; P difference <.001). An initial eGFR decline of greater than 10% (vs ≤10%) was associated with a higher risk of the primary cardiovascular outcome among those randomized to placebo (adjusted hazard ratio [aHR], 1.33; 95% CI, 1.10-1.62) but not among those randomized to dapagliflozin (aHR, 0.90; 95% CI, 0.74-1.09; P for interaction = .01). Similar associations were observed when alternative thresholds of initial eGFR decline were considered and when analyzed as a continuous measure. An initial eGFR decline of greater than 10% was not associated with adverse subsequent kidney composite outcomes in dapagliflozin-treated patients (aHR, 0.94; 95% CI, 0.49-1.82). Conclusions and Relevance: Among patients with HFmrEF or HFpEF treated with dapagliflozin, an initial eGFR decline was frequent but not associated with subsequent risk of cardiovascular or kidney events. These data reinforce clinical guidance that SGLT2is should not be interrupted or discontinued in response to an initial eGFR decline. Trial Registration: ClinicalTrials.gov Identifier: NCT03619213.

Sex Differences in Characteristics, Outcomes, and Treatment Response With Dapagliflozin Across the Range of Ejection Fraction in Patients With Heart Failure: Insights From DAPA-HF and DELIVER.

BACKGROUND: Sodium-glucose cotransporter-2 inhibitors have emerged as a key pharmacotherapy in heart failure (HF) with both reduced and preserved ejection fraction. The benefit of other HF therapies may be modified by sex, but whether sex modifies the treatment effect and safety profile of sodium-glucose cotransporter-2 inhibitors remains unclear. Our analyses aim to assess the effect of sex on the efficacy and safety of dapagliflozin. METHODS: In a prespecified patient-level pooled analysis of DAPA-HF (Dapagliflozin and Prevention of Adverse Outcomes in Heart Failure) and DELIVER (Dapagliflozin Evaluation to Improve the Lives of Patients With Preserved Ejection Fraction Heart Failure), clinical outcomes were compared by sex (including the composite of cardiovascular death or worsening HF events, cardiovascular death, all-cause death, total events [first and recurrent HF hospitalization and cardiovascular death], and Kansas City Cardiomyopathy Questionnaire scores) across the spectrum of left ventricular ejection fraction. RESULTS: Of a total of 11 007 randomized patients, 3856 (35%) were women. Women with HF were older and had higher body mass index but were less likely to have a history of diabetes and myocardial infarction or stroke and more likely to have hypertension and atrial fibrillation compared with men. At baseline, women had higher ejection fraction but worse Kansas City Cardiomyopathy Questionnaire scores than men did. After adjustment for baseline differences, women were less likely than men to experience cardiovascular death (adjusted hazard ratio, 0.69 [95% CI, 0.60-0.79]), all-cause death (adjusted hazard ratio, 0.69 [95% CI, 0.62-0.78]), HF hospitalizations (adjusted hazard ratio, 0.82 [95% CI, 0.72-0.94]), and total events (adjusted rate ratio, 0.77 [95% CI, 0.71-0.84]). Dapagliflozin reduced the primary end point in both men and women similarly (Pinteraction=0.77) with no sex-related differences in secondary outcomes (all Pinteraction>0.35) or safety events. The benefit of dapagliflozin was observed across the entire ejection fraction spectrum and was not modified by sex (Pinteraction>0.40). There were no sex-related differences in serious adverse events, adverse events, or drug discontinuation attributable to adverse events. CONCLUSIONS: In DAPA-HF and DELIVER, the response to dapagliflozin was similar between men and women. Sex did not modify the treatment effect of dapagliflozin across the range of ejection fraction.

Dapagliflozin and Kidney Outcomes in Patients With Heart Failure With Mildly Reduced or Preserved Ejection Fraction: A Prespecified Analysis of the DELIVER Randomized Clinical Trial.

Importance: Sodium-glucose cotransporter 2 inhibitors are known to reduce heart failure events and slow progression of kidney disease among patients with heart failure and a reduced ejection fraction. Objective: To determine the effect of dapagliflozin on cardiovascular and kidney outcomes and the influence of baseline kidney disease among patients with heart failure and a mildly reduced or preserved ejection fraction enrolled in the Dapagliflozin Evaluation to Improve the Lives of Patients With Preserved Ejection Fraction Heart Failure (DELIVER) trial. Design, Setting, and Participants: This was a prespecified analysis conducted from July 1 to September 18, 2022 of the DELIVER randomized clinical trial. This was an international, multicenter trial including patients with ejection fraction greater than 40% and estimated glomerular filtration rate (eGFR) of 25 mL/min/1.73 m2 or higher. Interventions: Dapagliflozin, 10 mg, per day or placebo. Main Outcomes and Measures: Outcomes assessed were whether baseline kidney function modified the treatment effect on the primary outcome (cardiovascular death or worsening heart failure). Also examined was the treatment effect on the prespecified outcomes of eGFR slope and a post hoc composite kidney outcome (first ≥50% decline in eGFR from baseline; first eGFR <15 mL/min/1.73 m2; end-stage kidney disease; death from kidney causes). Results: A total of 6262 patients (mean [SD] age, 72 [10] years; 3516 male [56%]) had mean (SD) eGFR measurements available: 61 (19) mL/min/1.73 m2; 3070 patients (49%) had an eGFR less than 60 mL/min/1.73 m2. The effect of dapagliflozin on the primary outcome was not influenced by baseline eGFR category (eGFR ≥60 mL/min/1.73 m2: hazard ratio [HR], 0.84; 95% CI, 0.70-1.00; eGFR 45-<60 mL/min/1.73 m2: HR, 0.68; 95% CI, 0.54-0.87; eGFR <45 mL/min/1.73 m2: HR, 0.93; 95% CI, 0.76-1.14; P for interaction = .16). Over a median (IQR) follow-up of 2.3 (1.7-2.8) years, the overall incidence rate of the kidney composite outcome was low (1.1 events per 100 patient-years) and was not affected by treatment with dapagliflozin (HR, 1.08; 95% CI, 0.79-1.49). However, dapagliflozin attenuated the decline in eGFR from baseline (difference, 0.5; 95% CI, 0.1-0.9 mL/min/1.73 m2 per year; P = .01) and from month 1 to 36 (difference, 1.4; 95% CI, 1.0-1.8) mL/min/1.73 m2 per year; P < .001). Conclusions and Relevance: Results of this prespecified analysis showed that baseline kidney function did not modify the benefit of dapagliflozin in patients with heart failure and a mildly reduced or preserved ejection fraction. Dapagliflozin did not significantly reduce the frequency of the kidney composite outcome, although the overall event rate was low. However, dapagliflozin slowed the rate of decline in eGFR compared with placebo. Trial Registration: ClinicalTrials.gov Identifier: NCT03619213.

Dapagliflozin in Patients Recently Hospitalized With Heart Failure and Mildly Reduced or Preserved Ejection Fraction.

BACKGROUND: Patients recently hospitalized for heart failure (HF) are at high risk for rehospitalization and death. OBJECTIVES: The purpose of this study was to investigate clinical outcomes and response to dapagliflozin in patients with HF with mildly reduced or preserved left ventricular ejection fraction (LVEF) who were enrolled during or following hospitalization. METHODS: The DELIVER (Dapagliflozin Evaluation to Improve the LIVES of Patients With PReserved Ejection Fraction Heart Failure) trial randomized patients with HF and LVEF >40% to dapagliflozin or placebo. DELIVER permitted randomization during or shortly after hospitalization for HF in clinically stable patients off intravenous HF therapies. This prespecified analysis investigated whether recent HF hospitalization modified risk of clinical events or response to dapagliflozin. The primary outcome was worsening HF event or cardiovascular death. RESULTS: Of 6,263 patients in DELIVER, 654 (10.4%) were randomized during HF hospitalization or within 30 days of discharge. Recent HF hospitalization was associated with greater risk of the primary outcome after multivariable adjustment (HR: 1.88; 95% CI: 1.60-2.21; P < 0.001). Dapagliflozin reduced the primary outcome by 22% in recently hospitalized patients (HR: 0.78; 95% CI: 0.60-1.03) and 18% in patients without recent hospitalization (HR: 0.82; 95% CI: 0.72-0.94; Pinteraction = 0.71). Rates of adverse events, including volume depletion, diabetic ketoacidosis, or renal events, were similar with dapagliflozin and placebo in recently hospitalized patients. CONCLUSIONS: Dapagliflozin safely reduced risk of worsening HF or cardiovascular death similarly in patients with and without history of recent HF hospitalization. Starting dapagliflozin during or shortly after HF hospitalization in patients with mildly reduced or preserved LVEF appears safe and effective. (Dapagliflozin Evaluation to Improve the LIVEs of Patients With PReserved Ejection Fraction Heart Failure [DELIVER]; NCT03619213).

Angiotensin-neprilysin inhibition and renal outcomes across the spectrum of ejection fraction in heart failure.

AIMS: Patients with heart failure are at higher risk of progression to end-stage renal disease (ESRD), regardless of ejection fraction (EF). We assessed the renal effects of angiotensin-neprilysin inhibition in a pooled analysis of 13 195 patients with heart failure with reduced and preserved EF. METHODS AND RESULTS: We combined data from PARADIGM-HF (EF ≤40%; n = 8399) and PARAGON-HF (EF ≥45%; n = 4796) in a pre-specified pooled analysis. We assessed the effect of treatment (sacubitril/valsartan vs. enalapril or valsartan) on a composite of either ≥50% reduction in estimated glomerular filtration rate (eGFR), ESRD, or death from renal causes, in addition to changes in eGFR slope. We assessed whether baseline renal function or EF modified the effect of therapy on renal outcomes. At randomization, eGFR was 68 ± 20 ml/min/1.73 m2 in PARADIGM-HF and 63 ± 19 ml/min/1.73 m2 in PARAGON-HF. The composite renal outcome occurred in 70 of 6594 patients (1.1%) in the sacubitril/valsartan group and in 123 of 6601 patients (1.9%) in the valsartan or enalapril group (hazard ratio 0.56, 95% confidence interval [CI] 0.42-0.75; p < 0.001). The mean eGFR change was -1.8 (95% CI -1.9 to -1.7) ml/min/1.73 m2 /year for the sacubitril/valsartan group, compared with -2.4 (95% CI -2.5 to -2.2) ml/min/1.73 m2 /year for the valsartan or enalapril group. The treatment effect on the composite renal endpoint was not modified by categories of baseline eGFR (p-interaction = 0.64), but was most pronounced in those with baseline EF between 30% and 60% (p-interaction = 0.001). CONCLUSIONS: In patients with heart failure, sacubitril/valsartan reduced the risk of serious adverse renal outcomes and slowed decline in eGFR, compared with valsartan or enalapril, independent of baseline renal function.

Excess mortality in solid organ transplant recipients hospitalized with COVID-19: A large-scale comparison of SOT recipients hospitalized with or without COVID-19.

BACKGROUND: Solid-organ transplant (SOT) recipients with coronavirus disease 2019 (COVID-19) have higher risk of adverse outcomes compared to the general population. Whether hospitalized SOT recipients with COVID-19 are at higher risk of mortality than SOT recipients hospitalized for other causes, including non-COVID-19 pneumonia, remains unclear. METHODS: We used logistic regression to compare outcomes of SOT recipients hospitalized with COVID-19 to non-COVID-19 related admissions and with non-COVID-19 pneumonia. RESULTS: Of 17,012 hospitalized SOT recipients, 1682 had COVID-19. Those with COVID-19 had higher odds of ICU admission (adjusted odds ratio [aOR] 2.12 [95%CI: 1.88-2.39]) and mechanical ventilation (aOR 3.75 [95%CI: 3.24-4.33]). COVID-19 was associated with higher odds of in-hospital death, which was more pronounced earlier in the pandemic (aOR 9.74 [95%CI: 7.08-13.39] for April/May vs. aOR 7.08 [95%CI: 5.62-8.93] for June through November 2020; P-interaction = .03). Compared to SOT recipients hospitalized with non-COVID-19 pneumonia, odds of in-hospital death were higher in SOT recipients with COVID-19 (aOR 2.44 [95% CI: 1.90-3.13]), regardless of time of hospitalization (P-interaction > .40). CONCLUSIONS: In this large cohort of SOT recipients, hospitalization with COVID-19 was associated with higher odds of complications and in-hospital mortality than non-COVID-19 related admissions, and 2.5-fold higher odds of in-hospital mortality, compared to SOT recipients with non-COVID-19 pneumonia.

Donor-derived Cryptococcus gattii sensu stricto infection in two kidney transplant recipients, southeastern United States.

Cryptococcus gattii infection is a rare cause of severe pulmonary disease and meningoencephalitis that has only recently been detected in the southeastern United States. We describe an organ transplant-associated outbreak of C. gattii infection involving an HIV-negative immunosuppressed donor in this region who died following new-onset headache and seizure of unknown cause. Retrospective cryptococcal antigen (CrAg) testing of donor serum was positive. Two of the three transplant recipients developed severe C. gattii infection 11 and 12 weeks following transplantation. One recipient died from severe pulmonary infection, identified on autopsy, and the other ill recipient survived following treatment for cryptococcal meningitis. This outbreak underscores the importance of considering cryptococcosis in patients with clinical findings suggestive of subacute meningitis or other central nervous system (CNS) pathology, and the potential benefit of routine pre-transplant donor CrAg screening using lateral flow assay to guide recipient antifungal prophylaxis. The case also adds to emerging evidence that C. gattii is a potential threat in the southeastern United States.

Serum uric acid, influence of sacubitril-valsartan, and cardiovascular outcomes in heart failure with preserved ejection fraction: PARAGON-HF.

AIMS: This study aimed to determine the prognostic value of serum uric acid (SUA) on outcomes in heart failure (HF) with preserved ejection fraction (HFpEF), and whether sacubitril-valsartan reduces SUA and use of SUA-related therapies. METHODS AND RESULTS: We analysed 4795 participants from the Prospective Comparison of ARNI [angiotensin receptor-neprilysin inhibitor] with ARB [angiotensin-receptor blockers] Global Outcomes in HF with Preserved Ejection Fraction (PARAGON-HF) trial. We related baseline hyperuricaemia (using age and gender adjusted assay definitions) to the primary outcome [cardiovascular (CV) death and total HF hospitalizations]. We assessed the associations between changes in SUA and Kansas City Cardiomyopathy Questionnaire Overall Summary Score (KCCQ-OSS) and other cardiac biomarkers from baseline to 4 months. We simultaneously adjusted for baseline and time-updated SUA to determine whether lowering SUA was associated with clinical benefit. The mean (± standard deviation) age of patients was 73 ± 8 years and 52% were women. After multivariable adjustment, hyperuricaemia was associated with increased risk for the primary outcome [rate ratio 1.61, 95% confidence interval (CI) 1.37-1.90]. The treatment effect of sacubitril-valsartan for the primary endpoint was not significantly modified by hyperuricaemia (P-value for interaction = 0.14). Sacubitril-valsartan reduced SUA by 0.38 mg/dL (95% CI 0.31-0.45) compared with valsartan at 4 months, with greater effect in those with elevated SUA vs. normal SUA (-0.51 mg/dL vs. -0.32 mg/dL) (P-value for interaction = 0.031). Sacubitril-valsartan reduced the odds of initiating SUA-related treatments by 32% during follow-up (P < 0.001). After multivariable adjustment, change in SUA was inversely associated with change in KCCQ-OSS and directly associated with high-sensitivity troponin T (P < 0.05). Time-updated SUA was a stronger predictor of adverse outcomes than baseline SUA. CONCLUSIONS: Serum uric acid independently predicted adverse outcomes in HFpEF. Sacubitril-valsartan reduced SUA and the initiation of related therapy compared with valsartan. Reductions in SUA were associated with improved outcomes.

Angiotensin-Neprilysin Inhibition and Renal Outcomes in Heart Failure With Preserved Ejection Fraction.

BACKGROUND: In patients with heart failure, chronic kidney disease is common and associated with a higher risk of renal events than in patients without chronic kidney disease. We assessed the renal effects of angiotensin/neprilysin inhibition in patients who have heart failure with preserved ejection fraction enrolled in the PARAGON-HF trial (Prospective Comparison of ARNI With ARB Global Outcomes in HF With Preserved Ejection Fraction). METHODS: In this randomized, double-blind, event-driven trial, we assigned 4822 patients who had heart failure with preserved ejection fraction to receive sacubitril/valsartan (n=2419) or valsartan (n=2403). Herein, we present the results of the prespecified renal composite outcome (time to first occurrence of either: ≥50% reduction in estimated glomerular filtration rate (eGFR), end-stage renal disease, or death from renal causes), the individual components of this composite, and the influence of therapy on eGFR slope. RESULTS: At randomization, eGFR was 63±19 mL·min-1·1.73 m-2. At study closure, the composite renal outcome occurred in 33 patients (1.4%) assigned to sacubitril/valsartan and 64 patients (2.7%) assigned to valsartan (hazard ratio, 0.50 [95% CI, 0.33-0.77]; P=0.001). The treatment effect on the composite renal end point did not differ according to the baseline eGFR (<60 versus ≥60 mL·min-1·1.73 m-2 (P-interaction=0.92). The decline in eGFR was less for sacubitril/valsartan than for valsartan (-2.0 [95% CI, -2.2 to -1.9] versus -2.7 [95% CI, -2.8 to -2.5] mL·min-1·1.73 m-2 per year). CONCLUSIONS: In patients with heart failure with preserved ejection fraction, sacubitril/valsartan reduced the risk of renal events, and slowed decline in eGFR, in comparison with valsartan. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01920711.

Lymph node fibroblastic reticular cells deposit fibrosis-associated collagen following organ transplantation.

Although the immune response within draining lymph nodes (DLNs) has been studied for decades, how their stromal compartment contributes to this process remains to be fully explored. Here, we show that donor mast cells were prominent activators of collagen I deposition by fibroblastic reticular cells (FRCs) in DLNs shortly following transplantation. Serial analysis of the DLN indicated that the LN stroma did not return to its baseline microarchitecture following organ rejection and that the DLN contained significant fibrosis following repetitive organ transplants. Using several FRC conditional-knockout mice, we show that induction of senescence in the FRCs of the DLN resulted in massive production of collagen I and a proinflammatory milieu within the DLN. Stimulation of herpes virus entry mediator (HVEM) on FRCs by its ligand LIGHT contributed chiefly to the induction of senescence in FRCs and overproduction of collagen I. Systemic administration of ex vivo-expanded FRCs to mice decreased DLN fibrosis and strengthened the effect of anti-CD40L in prolonging heart allograft survival. These data demonstrate that the transformation of FRCs into proinflammatory myofibroblasts is critically important for the maintenance of a proinflammatory milieu within a fibrotic DLN.

Nanodelivery of Mycophenolate Mofetil to the Organ Improves Transplant Vasculopathy.

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

The Role of Costimulatory Pathways in Transplant Tolerance.

Costimulation is a critical step in T-cell activation, and costimulatory blockade at the time of T cell activation leads to T-cell anergy and allograft tolerance in animal models of transplantation. CD28:B7 is the most important costimulatory pathway and the balance of signals between CD28 and cytotoxic T-lymphocyte associated protein 4 (CTLA-4) is a central determinant of transplant outcome. Form a clinical standpoint, CTLA-4 Ig is the only approved agent for costimulation blockade in transplantation. Advantages and disadvantages of its use are discussed. Progress in developing novel agents to target other pathways, including the promising CD40:CD154 pathway, is also discussed.

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

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

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

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

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

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

Diverse roles of TIM4 in immune activation: implications for alloimmunity.

PURPOSE OF REVIEW: T-cell immunoglobulin and mucin domain-containing molecule (TIM)4 is a costimulatory molecule and phosphatidylserine receptor. Its dominant function varies according to the expressing cell and site of activation. In recent years, studies have identified its role in diverse disease processes and increasingly in alloimmunity. Herein, we will comprehensively review the literature on TIM4 and outline its function in shaping the alloimmune response. RECENT FINDINGS: TIM4 expression on dendritic cells increases following transplantation. Blockade of TIM4 in vivo leads to increased differentiation of regulatory T cells and improved allograft survival. TIM4 binds phosphatidylserine-expressing apoptotic cells. Previously thought of as a tethering molecule, recent studies have demonstrated that TIM4 interacts with integrins to mediate uptake of apoptotic cells. TIM4 B cells have recently been identified, which produce high levels of IFNγ and promote allograft rejection. Targeting these B cells improved allograft survival and promoted the development of TIM1 regulatory B cells. SUMMARY: TIM4 is expressed in niche compartments and has many immunological effects. However, inhibition of TIM4 has been demonstrated to prolong allograft survival, through varied mechanisms. A unifying explanation for the role of TIM4 in alloimmunity remains to be found, but this pathway appears to hold considerable promise in transplantation.

Regulation of T cell alloimmunity by PI3Kγ and PI3Kδ.

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

Live Images of Donor Dendritic Cells Trafficking via CX3CR1 Pathway.

BACKGROUND: A number of studies have demonstrated the role of CX3CR1 in regulating the migration of monocytes into peripheral tissue and their transformation into dendritic cell (DC). No data are yet available on the importance of chemokine pathways in regulating homeostasis of DC in heart transplants. Recently, we showed that recipients of heart allografts from CX3CR1-/- donors show longer survival. To assess the trafficking of dDC, we have developed and tested a novel in vivo imaging tool in CX3CR1GFP/+ DC (B6 background) heart graft into BALB/c recipient model. RESULTS: Majority of GFP+ cells were noted in the middle of cardiac myocyte. However few hours post transplant, they experienced morphological changes including stretching their extensions (3 and 24 h). However, images from 72 h at cardiac graft showed many of GFP+ cells moved to vessel areas. GFP+ cells were detected in near vessel wall. Only one GFP+ cell was observed in three lymph nodes (two mesenteric and one inguinal) (72 h). CONCLUSION: Our data indicate that immediately post transplant dDC undergo morphological changes and traffic out of the organs via systemic circulation. While, we still noted presence of dDC in the transplanted organs, their trafficking to lymphoid tissue remains to be fully explored.