Tristan Legris

Infection with hepatitis E virus in kidney transplant recipients in southeastern France

Hepatitis E virus (HEV) is an emerging cause of acute hepatitis in Europe, particularly in southern France, and HEV is a new causative agent of chronic hepatitis and cirrhosis in immunocompromised patients. However, the data regarding HEV infection after kidney transplantation are still scarce with respect to the clinical issues that have been raised, and no study has specifically focused on kidney transplant recipients. This study described the clinical features and outcomes of HEV infections in a cohort of kidney transplant recipients living in southeastern France. The epidemiological, clinical, and virological characteristics of HEV infections diagnosed by PCR over a 53‐month period were retrospectively analyzed in a cohort of 1,350 kidney transplant recipients monitored at the Marseille University Hospital. Sixteen HEV infections were diagnosed, all of which were autochthonous and involved genotype 3 viruses (HEV‐3). Chronic infections occurred in 80% of these patients and resolved in half of the cases after a median time of 39 months. The rate of HEV clearance was 54% after a decrease in the dose of immunosuppressants. One patient developed liver cirrhosis 14 months after infection and experienced acute rejection after a decrease in the dose of immunosuppressants. Autochthonous HEV‐3 infections in kidney transplant recipients progress to chronicity in most cases and might be complicated by early liver cirrhosis. Chronic HEV infection can resolve following the reduction of immunosuppressive therapy, but ribavirin may be required if reduction of the immunosuppressant dose is not associated with HEV clearance or is inappropriate for the patient management. J. Med. Virol. 85:462–471, 2013.

Fractalkine Expression Induces Endothelial Progenitor Cell Lysis by Natural Killer Cells

Background Circulating CD34+ cells, a population that includes endothelial progenitors, participate in the maintenance of endothelial integrity. Better understanding of the mechanisms that regulate their survival is crucial to improve their regenerative activity in cardiovascular and renal diseases. Chemokine-receptor cross talk is critical in regulating cell homeostasis. We hypothesized that cell surface expression of the chemokine fractalkine (FKN) could target progenitor cell injury by Natural Killer (NK) cells, thereby limiting their availability for vascular repair. Methodology/Principal Findings We show that CD34+-derived Endothelial Colony Forming Cells (ECFC) can express FKN in response to TNF-α and IFN-γ inflammatory cytokines and that FKN expression by ECFC stimulates NK cell adhesion, NK cell-mediated ECFC lysis and microparticles release in vitro. The specific involvement of membrane FKN in these processes was demonstrated using FKN-transfected ECFC and anti-FKN blocking antibody. FKN expression was also evidenced on circulating CD34+ progenitor cells and was detected at higher frequency in kidney transplant recipients, when compared to healthy controls. The proportion of CD34+ cells expressing FKN was identified as an independent variable inversely correlated to CD34+ progenitor cell count. We further showed that treatment of CD34+ circulating cells isolated from adult blood donors with transplant serum or TNF-α/IFN-γ can induce FKN expression. Conclusions Our data highlights a novel mechanism by which FKN expression on CD34+ progenitor cells may target their NK cell mediated killing and participate to their immune depletion in transplant recipients. Considering the numerous diseased contexts shown to promote FKN expression, our data identify FKN as a hallmark of altered progenitor cell homeostasis with potential implications in better evaluation of vascular repair in patients.

Humoral immunity after kidney transplantation: impact of two randomized immunosuppressive protocols.

BACKGROUND Controlling alloimmune humoral response is a challenge in transplantation. Few studies have evaluated the impact of maintenance immunosuppression on blood humoral parameters. MATERIAL/METHODS We performed a post-hoc analysis on 307 kidney transplant recipients included in a prospective randomized trial comparing tacrolimus/mycophenolate mofetil (Tac/MMF) vs. cyclosporine/azathioprine (CsA/AZA), both used with antithymocyte globulin induction and steroids. Humoral parameters were analyzed at D0, D15, and M12. RESULTS IgG, IgA, and IgM levels decreased significantly as soon as D15 in both groups (–35%, –26%, and –35% respectively, vs. D0). At M12, although peripheral B-cell counts did not differ between the groups, Tac/MMF regimen was associated with lower IgG, IgA, and IgM levels than CsA/AZA (–5.9%, –14.6%, and –34%, respectively). Hypogammaglobulinemia at D15 was not associated with an increased risk of infections during the first year. The proportion of HLA-sensitized patients decreased in the Tac/MMF group (15.9% at D0 and 6.7% at M12, p=0.02) and remained stable in the CsA/AZA group (10.3% at D0 and 8.9% at M12, p=0.5). More patients sensitized at baseline became non-sensitized at M12 with Tac/MMF than with CsA/AZA. CONCLUSIONS Our results suggest humoral immunosuppression is better with Tac/MMF than with CsA/AZA during the first year of kidney transplantation.

Antibody-Dependent NK Cell Activation Is Associated with Late Kidney Allograft Dysfunction and the Complement-Independent Alloreactive Potential of Donor-Specific Antibodies

Although kidney transplantation remains the best treatment for end-stage renal failure, it is limited by chronic humoral aggression of the graft vasculature by donor-specific antibodies (DSAs). The complement-independent mechanisms that lead to the antibody-mediated rejection (ABMR) of kidney allografts remain poorly understood. Increasing lines of evidence have revealed the relevance of natural killer (NK) cells as innate immune effectors of antibody-dependent cellular cytotoxicity (ADCC), but few studies have investigated their alloreactive potential in the context of solid organ transplantation. Our study aimed to investigate the potential contribution of the antibody-dependent alloreactive function of NK cells to kidney graft dysfunction. We first conducted an observational study to investigate whether the cytotoxic function of NK cells is associated with chronic allograft dysfunction. The NK-Cellular Humoral Activation Test (NK-CHAT) was designed to evaluate the recipient and antibody-dependent reactivity of NK cells against allogeneic target cells. The release of CD107a/Lamp1+ cytotoxic granules, resulting from the recognition of rituximab-coated B cells by NK cells, was analyzed in 148 kidney transplant recipients (KTRs, mean graft duration: 6.2 years). Enhanced ADCC responsiveness was associated with reduced graft function and identified as an independent risk factor predicting a decline in the estimated glomerular filtration rate over a 1-year period (hazard ratio: 2.83). In a second approach, we used the NK-CHAT to reveal the cytotoxic potential of circulating alloantibodies in vitro. The level of CD16 engagement resulting from the in vitro recognition of serum-coated allogeneic B cells or splenic cells was further identified as a specific marker of DSA-induced ADCC. The NK-CHAT scoring of sera obtained from 40 patients at the time of transplant biopsy was associated with ABMR diagnosis. Our findings indicate that despite the administration of immunosuppressive treatments, robust ADCC responsiveness can be maintained in some KTRs. Because it evaluates both the Fab recognition of alloantigens and Fc-driven NK cell activation, the NK-CHAT represents a potentially valuable tool for the non-invasive and individualized evaluation of humoral risk during transplantation.

Systematic Serological Testing for Hepatitis E Virus in Kidney Transplant Recipients

ABSTRACT Hepatitis E virus (HEV) genotype 3 is endemic in Europe and hyperendemic in southern France. Recent reports of a high prevalence of HEV RNA in blood donations and in culinary specialties from this geographical area confirmed the endemicity of HEV and sources of viral transmission in this geographical area. HEV causes acute and chronic hepatitis in solid organ transplant recipients. Since March 2012, we have implemented systematic HEV serological testing in our cohort of kidney transplant recipients (KTRs) in Marseille in southeastern France. The aim of our study was to assess HEV exposure in this cohort between March 2012 and May 2014. During these 27 months, we found that 39% of the patients who underwent kidney transplantation had an anti-HEV IgG response using a sensitive microplate enzyme immunoassay. This seroprevalence was approximately 43% at both 1 and 8 years after, using the same assay. In addition, systematic HEV serological testing detected 6 cases of HEV infection among 578 KTRs (1%) during the 27 months of the study, with 5 at an acute stage and 1 at a chronic stage. In conclusion, continuous HEV monitoring in this population is useful for better understanding the epidemiology of HEV in France, because these patients are a well-monitored population. Moreover, HEV monitoring in KTRs is clinically relevant because HEV represents a clinical threat in these patients. Nevertheless, HEV serological testing may be more fruitful for identifying HEV infections when performed in cases of biological liver abnormalities than when performed systematically.

Nocardiosis in the south of France over a 10-years period, 2004–2014

BACKGROUND Nocardiosis is a rare disease with polymorphic presentations. The epidemiology and clinical presentation could change with the increasing number of immunocompromised patients. METHODS The medical records and microbiological data of patients affected by nocardiosis and treated at the university hospitals of Marseille between 2004 and 2014 were analyzed retrospectively. RESULTS The cases of 34 patients infected by Nocardia spp during this period were analyzed. The main underlying conditions were transplantation (n=15), malignancy (n=9), cystic fibrosis (n=4), and immune disease (n=3); no immunodeficiency condition was observed for three patients. No case of AIDS was observed. At diagnosis, 61.8% had received steroids for over 3 months. Four clinical presentations were identified, depending on the underlying condition: the disseminated form (50.0%) and the visceral isolated form (26.5%) in severely immunocompromised patients, the bronchial form (14.7%) in patients with chronic lung disease, and the cutaneous isolated form (8.8%) in immunocompetent patients. Nocardia farcinica was the main species identified (26.5%). Trimethoprim-sulfamethoxazole was prescribed in 68.0% of patients, and 38.0% underwent surgery. Mortality was 11.7%, and the patients who died had disseminated or visceral nocardiosis. CONCLUSIONS The clinical presentation and outcome of nocardiosis depend on the patients initial immune status and underlying pulmonary condition. Severe forms were all iatrogenic, occurring after treatments altering the immune system.

Delayed diagnosis of fibrinogen Aα-chain amyloidosis after dual heart-kidney transplantation.

Dear Sir, Besides light-chain and amyloid A amyloidosis, hereditary autosomal dominant amyloidosis is considered a rare disease. Nevertheless, it is frequently misdiagnosed [1]. Fibrinogen Aa-chain (AFib) amyloidosis involves the kidneys and causes proteinuria, hypertension, and progression to endstage renal disease (ESRD). Isolated renal transplantation has been proposed when ESRD is reached, but it is associated with risk of recurrence and premature graft loss [2,3]. Moreover, cardiac amyloidosis has been recently described among mutated patients [4] but its precise pathogenesis remains debated [2,5]. Heart transplantation in the course of AFib amyloidosis has, to our knowledge, never been reported. A 55-year-old smoker Caucasian male presented with a large inaugural anterior myocardial infarction in 2003 with coronary angiography showing an atherosclerotic plaque of the left anterior descending artery. Despite angioplasty and stent implantation, severe heart failure appeared (left ventricular ejection fraction = 20% with dilated left ventricle) without other echocardiographic signs suggestive of amyloid cardiopathy. Moderate renal failure [serum creatinine level (SCr) = 130 lmol/l] with proteinuria at 1.4 g/l and hypertension were contemporaneously noticed but not explored. In 2004, deterioration of kidney function (SCr = 245 lmol/l) and massive albuminuria at 6 g/day led the patient to the first nephrological assessment. Renal ultrasound evaluation revealed two small kidneys of 8 cm that did not allow renal biopsy. Family tree was unremarkable and immunological or infectious tests failed to explain this glomerulonephritis. Decline of renal and cardiac functions was prompt. He started hemodialysis at the end of 2004 and was placed on the waiting list for combined heart –kidney transplantation. In November 2005 he received a combined heart–kidney transplant from a deceased 51-year-old male donor with no medical history. Transplantation was successful: the lowest SCr was 108 lmol/l at month 1. He received cyclosporin A, mycophenolate mofetil, and prednisone after an initial induction with anti-thymocyte globulin. At M6, a first kidney transplant biopsy (performed for SCr increased to 145 lmol/l with proteinuria at 0.7 g/day) showed chronic aspecific vascular endarteritis lesions. SCr then stabilized between 150 and 190 lmol/l with low proteinuria. Annual coronary angiographies were normal until 2009, when a nonsignificant stenosis of the right coronary artery and a mild elevation of pulmonary capillary wedge pressure (18 mmHg) were suggestive of chronic rejection. Repeated cardiac protocol biopsies revealed asymptomatic cardiac rejections grade 1R between 2007 and 2009. Repeated echocardiographs showed septum wall thickening (14 mm), an impaired relaxation pattern with restrictive profile, and a normal ejection fraction (65%). Interestingly, the septum had a granular sparkling appearance. Finally, he received a pacemaker in 2010 for repeated episodes of complete atrioventricular block. In 2011, he was admitted for acute diarrhea secondary to intestinal cryptosporidiosis complicated by acute pre-renal failure (SCr: 625 lmol/l). He was treated by a high-volume of parenteral fluid and nitazoxanide. Despite his improved clinical status, we observed a stagnation of SCr at 260 lmol/l, without hypertension, hematuria, or proteinuria. A second renal biopsy revealed glomerular deposits of amorphous eosinophilic material without interstitial or vascular deposits. Congo red staining was positive with reddish-brown material that showed red birefringence under polarized light (Fig. 1, panels a and b). Immunofluorescence study showed no reactivity for j and k light-chain, AA protein, transthyretin, lysosyme, apolipoprotein, leukocyte chemotactic factor 2, and b2-microglobulin but glomerular deposits were labeled with anti-AFib antibodies. Genetic analysis confirmed a heterozygous p.E526V mutation of the AFib gene. Interestingly, careful retrospective examination of his native explanted heart also revealed mild amyloid deposits within small myocardial vessels (Fig. 1, panels c and d). However, retrospective examination of graft endomyocardial biopsies did not show amyloidosis. Our patient is currently well; Scr has stabilized at 230 lmol/l with mild proteinuria (0.5 g/day) under ACE inhibition.

Indoxyl Sulfate Upregulates Liver P-Glycoprotein Expression and Activity through Aryl Hydrocarbon Receptor Signaling

In patients with CKD, not only renal but also, nonrenal clearance of drugs is altered. Uremic toxins could modify the expression and/or activity of drug transporters in the liver. We tested whether the uremic toxin indoxyl sulfate (IS), an endogenous ligand of the transcription factor aryl hydrocarbon receptor, could change the expression of the following liver transporters involved in drug clearance: SLC10A1, SLC22A1, SLC22A7, SLC47A1, SLCO1B1, SLCO1B3, SLCO2B1, ABCB1, ABCB11, ABCC2, ABCC3, ABCC4, ABCC6, and ABCG2 We showed that IS increases the expression and activity of the efflux transporter P-glycoprotein (P-gp) encoded by ABCB1 in human hepatoma cells (HepG2) without modifying the expression of the other transporters. This effect depended on the aryl hydrocarbon receptor pathway. Presence of human albumin at physiologic concentration in the culture medium did not abolish the effect of IS. In two mouse models of CKD, the decline in renal function associated with the accumulation of IS in serum and the specific upregulation of Abcb1a in the liver. Additionally, among 109 heart or kidney transplant recipients with CKD, those with higher serum levels of IS needed higher doses of cyclosporin, a P-gp substrate, to obtain the cyclosporin target blood concentration. This need associated with serum levels of IS independent of renal function. These findings suggest that increased activity of P-gp could be responsible for increased hepatic cyclosporin clearance. Altogether, these results suggest that uremic toxins, such as IS, through effects on drug transporters, may modify the nonrenal clearance of drugs in patients with CKD.

Brincidofovir Use after Foscarnet Crystal Nephropathy in a Kidney Transplant Recipient with Multiresistant Cytomegalovirus Infection

Background. Cytomegalovirus (CMV) antiviral drug resistance constitutes an increasing challenge in transplantation. Foscarnet is usually proposed when resistance for ganciclovir is suspected, but its use is limited by its nephrotoxicity. Case Presentation. We report a case of multiresistant CMV disease in a kidney transplant recipient. Foscarnet was prescribed after ganciclovir treatment failure in a patient with two mutations in the UL97 viral gene. Foscarnet induced biopsy-proven kidney crystal precipitation that resulted in severe acute transplant failure and nephrotic syndrome. Despite a large decrease in immunosuppression, CMV disease was not controlled and a salvage therapy with Brincidofovir (BCV), which is an oral lipid conjugate of cidofovir with limited nephrotoxicity, was attempted. Clinical and virological remission was observed after a 21-day course of BCV, despite mild and reversible liver toxicity. However, a new relapse could not be effectively cured by BCV due to a new mutation in the UL54 gene, which is known to confer resistance to cidofovir. A new course of foscarnet finally resulted in prolonged CMV remission. Herein, we present a review of foscarnet nephropathy cases in solid-organ transplanted patients. Conclusions. This unique case highlights the potential benefit of BCV use during resistant CMV infection, although mutations in the UL54 gene may limit its therapeutic efficacy. These findings need to be confirmed in clinical trials.

Osseous metaplasia in a kidney allograft

Osseous metaplasia is defined by the presence of heterotopic normal bone tissue in a soft tissue. The bone matrix is associated with osteoblasts, osteoclasts, adipocytes and haematopoietic stem cells. Osseous metaplasia pathophysiology is not well known, but many factors have been incriminated including chronic inflammation and chronic ischaemia. We describe the second case of osseous metaplasia in a kidney allograft. Numerous factors might favour its development including factors linked to transplantation failure environment.