B cell survival in intragraft tertiary lymphoid organs after rituximab therapy.

BACKGROUND: Rituximab is emerging as a potent therapeutic option in chronic inflammatory diseases associated with a prominent humoral component. Recent studies have demonstrated that chronic inflammatory infiltrate organize progressively themselves into ectopic lymphoid tissues (tertiary lymphoid organs; TLOs) supporting a local humoral immune response. In the present study, we evaluated the impact of rituximab therapy on TLOs associated with chronic active antibody-mediated rejection, a prototypic humoral chronic inflammatory condition. METHODS: Renal allografts removed for terminal chronic rejection were prospectively collected in four transplantation centers over 4 years. Among 38 grafts collected, two were explanted after rituximab therapy for chronic active antibody-mediated rejection. Clinical characteristics and circulating B cell count were recorded for these two patients. The composition and the microarchitecture of the inflammatory infiltrate were analyzed by flow cytometry and immunohistochemistry. Organotypic cultures were performed to evaluate the intragraft production of alloantibody. Levels of expression of BAFF (Blys, CD257) were evaluated by quantitative reverse transcriptase-polymerase chain reaction. RESULTS: Despite the complete depletion of circulating B cells in peripheral blood, TLOs were evidenced in the interstitium of both explanted grafts. Their functionality was assessed by the demonstration of a persistent local production of alloantibody. BAFF, a potent survival factor for B cells, was found to be overexpressed (both at the gene and the protein levels) in chronically rejected grafts when compared with normal kidneys and lymph nodes. CONCLUSIONS: In certain patients, inflammatory microenvironment provides BAFF-dependent paracrine survival signal to B-cells in TLOs, allowing them to escape rituximab-induced apoptosis, thereby thwarting therapeutic efficiency.

Angioedema in renal transplant recipients on sirolimus.

BACKGROUND: Most drug-associated angioedemas are induced by angiotensin-converting enzyme inhibitors, angiotensin II receptor antagonists, or nonsteroidal anti-inflammatory drugs. Recently, the responsibility of immunosuppressive agents given to transplant recipients in the development of angioedema has been discussed. OBJECTIVE: To describe, in detail, angioedema episodes in renal transplant recipients (RTRs) on sirolimus. METHODS: A cross-sectional study in a university hospital. Eighty consecutive RTRs on sirolimus were studied. RESULTS: Angioedema without urticaria occurred a mean of 5 times in 12/80 (15%) RTRs taking sirolimus. It was predominantly located on the face (83%), with mucous membrane involvement in 7 (58%) patients, and was life threatening in 1. Another putative cofactor for angioedema without urticaria was identified in 9 (75%) patients: drugs (n=8), food allergy or physical activity (n=3). Tacrolimus intake was significantly associated with sirolimus-associated angioedema. CONCLUSION: Our results suggested a causal relationship between sirolimus and angioedema in RTRs.

Acne in recipients of renal transplantation treated with sirolimus: clinical, microbiologic, histologic, therapeutic, and pathogenic aspects.

We evaluated the clinical characteristics of sirolimus-induced acne in 80 recipients of renal transplantation. It developed in 36 of 48 (75%) men and 2 of 32 (6%) women. Lesion locations and clinical, bacteriologic, and histologic features differentiated sirolimus-induced acne from acne vulgaris, but therapeutic management was similar. The main limitation for this study was the absence of a control group without sirolimus. Epidermal growth factor inhibition by sirolimus is a plausible explanation for this acne.

Anemia after late introduction of sirolimus may correlate with biochemical evidence of a chronic inflammatory state.

BACKGROUND: The responsibility of sirolimus (SRL) for postrenal transplant anemia has never been proven, because SRL is usually combined with myelotoxic drugs, and because of the high incidence of anemia in the posttransplant period. METHODS: We retrospectively analyzed anemia in 46 renal transplant recipients, who had been switched from calcineurin inhibitors to SRL for biopsy-proven chronic allograft nephropathy. RESULTS: The mean decrease in hemoglobin (Hb) after SRL introduction was 2.8 g/dl. The 24 patients, whose Hb fell by >or=2 g/dl, displayed microcytic aregenerative anemia with low serum iron despite high ferritinemia, consistent with anemia of chronic inflammatory states. Fibrinogen and CRP levels increased in these patients after sirolimus introduction. We subsequently focused our study on eight patients without confounding factors of anemia. Anemia improved in all eight after SRL withdrawal. IL6 and TNFalpha at the nadir of anemia were significantly higher than before SRL introduction and after its withdrawal. Decreases in Hb correlated with increases in proinflammatory cytokine levels in a linear regression model. Unchanged serum IL10 levels measured at the nadir of anemia were discordant with the inflammatory state. CONCLUSIONS: Late introduction of SRL may induce anemia and correlates with biochemical evidence of a chronic inflammatory state possibly due to defective IL10-dependent inflammatory autoregulation.

Consequences of genetic polymorphisms for sirolimus requirements after renal transplant in patients on primary sirolimus therapy.

Sirolimus (SRL) is a substrate for cytochromes P-450 3A and P-glycoprotein, the product of the MDR1 gene. We postulated that single nucleotide polymorphisms (SNPs) of these genes could be associated with inter-individual variations in SRL requirements. We then evaluated in 149 renal transplant recipients the effect of polymorphisms CYP3A4*1/*1B, CYP3A5*1/*3 and MDR1 SNPs in exon 12, 21 and 26 on SRL concentration/dose (C/D) ratio 3 months after sirolimus introduction. SRL C/D ratio was significantly higher in patients treated with calcineurin inhibitors. The CYP3A4*1B and CYP3A5*1 alleles were present in 17% and 21% of patients, respectively. When treated with a SRL-based therapy and low-dose steroids, patients carrying the CYP3A4*1B or the CYP3A5*1 alleles required significantly more SRL to achieve adequate blood trough concentrations (p < 0.01 and p < 0.02, respectively). None of the MDR1 SNPs was associated with the SRL concentration/dose ratio. These findings suggest that the variations in SRL requirements are secondary to both genetic and non-genetic factors including pharmacokinetic interactions. In patients with SRL-based therapy, genotyping of the CYP3As genes may help to optimize the SRL management in transplant recipients.

Cutaneous adverse events in renal transplant recipients receiving sirolimus-based therapy.

BACKGROUND: Sirolimus is an immunosuppressive drug recently developed for organ transplantation. Its mechanism of action, independent of calcineurin, is different from that of cyclosporine and tacrolimus, two calcineurin inhibitors (CIs). Because the toxicity of CIs is partly the result of calcineurin blockade, sirolimus exhibits a different toxicity profile. In this study, we evaluated the profile, frequency, and severity of cutaneous adverse events in renal transplant recipients receiving sirolimus-based therapy. PATIENTS AND METHODS: A systematic and in-depth evaluation of skin, mucous membranes, nails, and hair was performed in 80 renal transplant recipients receiving sirolimus-based therapy. The mean duration of the graft was 6 years and of sirolimus treatment was 18 months. Mycophenolate mofetil and steroids were combined with sirolimus for 74 patients. Sirolimus was used as first immunosuppressive therapy for 36 patients, and 44 patients were switched from CIs to sirolimus. RESULTS: Seventy-nine patients (99%) experienced cutaneous adverse events. Twenty patients (25%) demonstrated serious adverse events, and six patients (7%) stopped sirolimus during the 3 months after the study because of cutaneous events. The most frequent of these were pilosebaceous apparatus involvement, including acne-like eruptions (46%), scalp folliculitis (26%), and hidradenitis suppurativa (12%); edematous complaints, including chronic edemas (55%) and angioedema (15%); mucous membrane disorders, including aphthous ulceration (60%), epistaxis (60%), chronic gingivitis (20%), and chronic fissure of the lips (11%); and last, nail disorders including chronic onychopathy (74%) and periungual infections (16%). CONCLUSIONS: Skin disorders are frequent in renal transplant recipients receiving sirolimus as a long-term therapy. Despite the usually mild nature of skin events, they are often the reason for stopping sirolimus.

Renal-transplant recipients and sun protection.

BACKGROUND: The incidence of skin carcinomas in organ-transplant recipients is high. The main factors implicated in carcinogenesis are immune suppression and ultraviolet radiation. Only the second is avoidable. We have evaluated knowledge of and compliance with sun protection measures among renal-transplant recipients (RTR). METHODS: A survey by means of a questionnaire including questions about clinical data, knowledge of, and compliance with sun protection was given. The questionnaire was given to 520 consecutive RTR followed up in a single center, and 445 (86%) answered. RESULTS: Of the responders, 91% have been informed of the need for sun protection, in 80% of cases by dermatologists. Sixty-eight percent used more protective measures abroad than at home, 63% avoided going outside during the hottest midday hours, 63% used sunscreen regularly, but 46% used one or less tube of sunscreen a year. A hat was always worn in the sun by 35% and long sleeves by 36%. Women and fair-skinned individuals complied better with protective measures. A minority of patients knew that ultraviolet radiation carries a risk of skin cancer. CONCLUSIONS: This survey shows that most RTR are aware of the need for sun protection, but only a minority take adequate protection measures. The better results observed in this study than in previous published investigations may be caused by the great involvement of dermatologists in the care of RTR in our institution. The results of this survey underline the need to inform RTR better about sun-protection measures and the importance of cooperation between transplant physicians and dermatologists.