Poor seroprotection but allosensitization after adjuvanted pandemic influenza H1N1 vaccine in kidney transplant recipients.

BACKGROUND: Seasonal and pandemic influenza virus infections in renal transplant patients are associated with poor outcomes. During the pandemic of 2009-2010, the AS03-adjuvanted monovalent H1N1 influenza vaccine was recommended for transplant recipients, although its immunogenicity in this population was unknown. We sought to determine the safety and immunogenicity of an adjuvant-containing vaccine against pandemic influenza A H1N1 2009 (pH1N1) administered to kidney transplant recipients. METHODS: We prospectively enrolled 124 adult kidney transplant recipients in the fall of 2009 at two transplant centers. Cohort 1 (n = 42) was assessed before and after pH1N1 immunization, while Cohort 2 (n = 82) was only assessed post immunization. Humoral response was measured by the hemagglutination inhibition assay. Vaccine safety was assessed by adverse event reporting, graft function, and human leukocyte antigen (HLA) alloantibody measurements. RESULTS: Cohort 1 had a low rate of baseline seroprotection to pH1N1 (7%) and a low rate of seroprotection after immunization (31%). No patient <6 months post transplant (n = 5) achieved seroprotection. Seroprotection rate was greater in patients receiving double as compared with triple immunosuppression (80% vs. 24%, P = 0.01). In Cohort 2, post-immunization seroprotection was 35%. In both cohorts, no confirmed cases of pH1N1 infection occurred. No difference was seen in estimated glomerular filtration rate before (54.3 mL/min/1.73 m(2) ) and after (53.8 mL/min/1.73 m(2) ) immunization, and no acute rejections had occurred after immunization at last follow-up. In Cohort 1, 11.9% of patients developed new anti-HLA antibodies. CONCLUSION: An adjuvant-containing vaccine to pH1N1 provided poor seroprotection in renal transplant recipients. Receiving triple immunosuppression was associated with a poor seroresponse. Vaccination appeared safe, but some patients developed new anti-HLA antibodies post vaccination. Alternative strategies to improve vaccine responses are necessary.

RIP2 is required for NOD signaling but not for Th1 cell differentiation and cellular allograft rejection.

Two previous reports that receptor-interacting protein (RIP)-2 knockout (RIP2-/-) mice had defective nuclear factor-kappa B (NF-kappaB) signaling and T helper (Th)1 immune responses had led us to believe that this putative serine-threonine kinase might be a possible target for transplant immunosuppression. Thus, we tested whether RIP2-/- mice were able to reject vascularized allografts. Surprisingly, we found that T cells from RIP2-/- mice proliferated and produced interferon (IFN)-gamma after allostimulation in vitro. Moreover, naïve RIP2-/- CD4+ T cells differentiated normally into Th1 or Th2 cells under appropriate cytokine microenvironments. Consistent with these findings, no difference in allograft survival was observed between wild-type and RIP2-/- recipient mice, and rejection had similar pathology and cytokine profiles in both types of recipients. RIP2 deficiency was associated with defective NOD signaling, but this did not affect T-cell receptor (TCR)-dependent activation of the canonical NF-kappaB signaling or expression of NF-kappaB genes in rejecting allografts. Our data demonstrate that RIP2-deficient mice have intact canonical NF-kappaB signaling and can mount Th1-mediated alloresponses and reject vascularized allografts as efficiently as wild-type mice, thus arguing against RIP2 as a primary target for immunosuppression.

Tubulitis and epithelial cell alterations in mouse kidney transplant rejection are independent of CD103, perforin or granzymes A/B.

One of the defining lesions of kidney allograft rejection is epithelial deterioration and invasion by inflammatory cells (tubulitis). We examined epithelial changes and their relationship to effector T cells and to CD103/E-cadherin interactions in mouse kidney allografts. Rejecting allografts showed interstitial mononuclear infiltration from day 5. Loss of epithelial mass, estimated by tubular surface area, and tubulitis were minimal through day 7 and severe by day 21. Tubules in day 21 allografts manifested severe reduction of E-cadherin and Ksp-cadherin by immunostaining with redistribution to the apical membrane, indicating loss of polarity. By flow cytometry T cells isolated from allografts were 25% CD103+. Laser capture microdissection and RT-PCR showed increased CD103 mRNA in the interstitium and tubules. However, allografts in hosts lacking CD103 developed tubulitis, cadherin loss, and epithelial deterioration similar to wild-type hosts. The loss of cadherins and epithelial mass was also independent of perforin and granzymes A and B. Thus rejection is characterized by severe tubular deterioration associated with CD103+ T cells but not mediated by CD103/cadherin interactions or granzyme-perforin cytotoxic mechanisms. We suggest that alloimmune effector T cells mediate epithelial injury by contact-independent mechanisms related to delayed type hypersensitivity, followed by invasion of the altered epithelium to produce tubulitis.

Functional alpha4-integrin: a newly identified pathway of neutrophil recruitment in critically ill septic patients.

Using a novel flow chamber assay system and whole blood, we show that leukocytes from septic individuals have a four-fold elevation of adhesion, but not rolling, on a P-selectin/beta2-integrin substrate. Most leukocytes from septic patients (but not healthy controls) that bound vascular cell adhesion molecule 1 (VCAM-1) were neutrophils. All adhesion was inhibited with an antibody specific for the VCAM-1 ligand alpha4-integrin. The alpha4-integrin was present on neutrophils from septic patients but not on neutrophils from patients with localized bacterial infections. The plasma milieu of septic patients was sufficient to induce neutrophils from healthy subjects to bind VCAM-1 under flow conditions. This is the first description of alpha4-integrin/VCAM-1 pathway of neutrophil recruitment in human disease. This pathway may provide a new therapeutic target to reduce inappropriate neutrophil adhesion without altering the normal yet critical beta2-integrin-mediated adhesive function of neutrophils.

Inhaled NO as a viable antiadhesive therapy for ischemia/reperfusion injury of distal microvascular beds.

Inhaled nitric oxide (NO) is being used more and more in intensive care units as a modality to improve the outcome of patients with pulmonary complications. Our objective was to demonstrate that inhaled NO could impact upon a distally inflamed microvasculature-improving perfusion, leukocyte adhesive interactions, and endothelial dysfunction. Using intravital microscopy to visualize ischemia/reperfusion of postcapillary venules, we were able to demonstrate that the reduction in perfusion, the dramatic increase in leukocyte rolling, adhesion, and emigration, and the endothelial dysfunction could all be significantly abrogated with 80 ppm, but not 20 ppm inhaled NO. Perfusing whole blood directly over an inert P-selectin and CD18 ligand substratum incorporated in a flow chamber recruited the same number of rolling and adhering leukocytes from NO-ventilated and non-NO-ventilated animals, suggesting that inhaled NO was not directly affecting leukocytes. To demonstrate that inhaled NO was actually reaching the peripheral microvasculature in vivo, we applied a NO synthase inhibitor locally to the feline mesentery and demonstrated that the vasoconstriction, as well as leukocyte recruitment, were essentially abolished by inhaled NO, suggesting that a NO-depleted peripheral microvasculature could be replenished with inhaled NO in vivo. Finally, inhaled NO at the same concentration that was effective in ischemia/reperfusion did not affect vascular alterations, leukocyte recruitment, and endothelial dysfunction associated with endotoxemia in the feline mesentery. In conclusion, our data for the first time demonstrate a role for inhaled NO as a therapeutic delivery system to the peripheral microvasculature, showing tremendous efficacy as an antiadhesive, antivasoconstrictive, and antipermeabilizing molecule in NO-depleted tissues, but not normal microvessels or vessels that have an abundance of NO (LPS-treated). The notion that blood borne molecules have NO carrying capacity is conceptually consistent with our observations.