Profound inhibition of CD73-dependent formation of anti-inflammatory adenosine in B cells of SLE patients.

BACKGROUND: Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that leads to a breakdown of tolerance to self-antigens resulting in inflammation and organ damage. The anti-inflammatory activity of CD73-derived adenosine is well documented, however, its role in SLE pathogenesis is unknown. METHODS: Human peripheral blood immune cells were obtained from adult SLE patients (SLE) and healthy controls (HC). Expression and activity of purinergic ectoenzymes were assessed by qRT-PCR, flow cytometry and HPLC. Genes encoding purinergic ectoenzymes in SLE patients were analysed with targeted DNA sequencing. FINDINGS: Among circulating immune cells (both in HC and SLE), CD73 was most highly expressed on B cells, which was mirrored by high enzymatic activity only in HC. CD73 protein molecular weight was unchanged in SLE, however, the enzymatic activity of CD73 on SLE B cells was almost fully abolished. Accordingly, AMP accumulated in cultured SLE B cells. A similar discrepancy between protein expression and enzymatic activity was observed for NAD-degrading CD38 on SLE B cells. No differences were found in the rate of extracellular ATP degradation and expression of CD39, CD203a/c, and CD157. DNA sequencing identified no coding variants in CD73 in SLE patients. INTERPRETATION: We describe a new pathomechanism for SLE, by which inactivation of CD73 on B cells produces less anti-inflammatory adenosine, resulting in immune cell activation. CD73 inactivation was not due to genetic variation but may be related to posttranslational modification. FUNDING: The German Research Council, Medical Faculty of the Heinrich-Heine-University Duesseldorf, Hiller Research Foundation, and Cardiovascular Research Institute Duesseldorf.

Impact of aldosterone synthase gene C-344T polymorphism on IgA nephropathy.

AIM: In the past years, aldosterone has been identified as an important mediator of renal injury. In this study, we evaluated the influence of C-344T polymorphism of aldosterone synthase gene, associated with serum aldosterone levels and the development of arterial hypertension, on IgA nephropathy (IgAN). METHODS: We studied n = 143 patients with biopsy-proven IgAN followed up for 7.1 ± 6.2 years. Patients were classified according to the slope of reciprocal serum creatinine into group A (slow progressors, n = 93) and group B (fast progressors, n = 50). One hundred healthy volunteers were analyzed as controls. The biopsies of n = 79 patients were reviewed and analyzed by the same pathologist. Aldosterone synthase gene C-344T polymorphism was determined by polymerase chain reaction amplification. RESULTS: The genotype distribution was similar in patients and control subjects [not significant (ns)]. Age, initial renal function, proteinuria, and blood pressure did not differ significantly between patients with different genotypes (ns). The percentage of sclerosed glomeruli tended to be higher among patients carrying the CC/CT genotypes (29.4 ± 26.5% vs. 21.7 ± 25.2% in TT genotype; ns). C-344T polymorphism was associated with the progression of IgAN as shown by the different genotype frequencies in group Α (slow progressors, CC/CT: 60.2%, TT: 39.8%) and group B (fast progressors, CC/CT: 78.0%, TT: 22:0%; p = 0.032). CONCLUSION: Our results indicate that aldosterone synthase gene C-344T polymorphism is a risk factor for accelerated progression in Caucasian patients with IgAN.

New influenza A (H1N1/09) in three renal transplant patients.

The pandemic new influenza A (H1N1/09) virus may be especially threatening for immunosuppressed renal transplant patients as they are at increased risk for complications, prolonged infection and mortality. This is the first case report of renal transplant patients with PCR-confirmed H1N1 respiratory tract infection. They showed a surprisingly mild clinical course despite respiratory fungal or viral co-infections in two cases. Treatment with oseltamivir in standard dosage was immediately started after diagnosis and proved to be rapidly beneficial with respect to clinical outcome and virus shedding without deteriorating renal transplant function.

Impact of genetic polymorphisms of the renin-angiotensin system and of non-genetic factors on kidney transplant function--a single-center experience.

Renin-angiotensin-aldosterone system (RAAS) polymorphisms such as the angiotensinogen-gene-M235T-, the angiotensin-conversion enzyme (ACE)-gene I/D- and the angiotensin-II-type 1-receptor-(AT1R)-A1166C-polymorphism have been implicated in renal insufficiency and hypertension. We studied the association of these RAAS genotypes and non-genetic factors with transplant function and hypertension after renal graft transplantation (NTX). A total of 229 renal graft recipients, transplanted at a single center, were monitored up to 54 months and genotyped using polymerase chain reaction. The prevalence of the genotypes was comparable to a control group of healthy volunteers. Genotype and clinical outcome was analyzed using ANOVA, while the k-nearest neighbor method was used for a pattern recognition analysis of the complete database. Hypertension after NTX was not influenced by the RAAS polymorphisms. The DD-genotype of the ACE-I/D-polymorphism was associated with significantly deteriorated renal transplant function during the months 18 to 30 after transplantation according to ANOVA at p < 0.05, as were non-genetic factors like long hospitalization, poor primary transplant function, and frequent rejections. Pattern recognition identified, the use of cyclosporine (odds ratio of 4.25) and the use of Ang II-receptor-blockers at discharge indicating the need of effective antihypertensive treatment (odds ratio of 3.26) as risk factors for transplant function loss. Altogether, the significant impact of the DD-genotype on the outcome after renal transplantation emphasizes the early identification of RAAS genotypes.