Impact of NOD2/CARD15 haplotypes on the outcome after kidney transplantation

Chronic allograft nephropathy and (cardiovascular) death with functioning graft are major causes of late graft loss. NOD2/CARD15 (nucleotide oligomerization domain-2/caspase-recruiting activating domain-15), an intracellular receptor that is part of the innate immunity repertoire, has convincingly been shown to be involved in infection/inflammation-associated diseases. Specifically, NOD2/CARD15 polymorphisms are clearly associated with Crohn's disease and transplant-associated mortality after bone marrow transplantation. The aim of this study was to clarify the relevance of NOD2/CARD15-haplotypes in kidney transplantation. Three hundred fifty-two patients receiving their first kidney transplant were genotyped for the three major NOD2/CARD15 polymorphisms, R702W, G908R, and 1007fs with subsequent reconstruction of the different haplotypes. Four different NOD2/CARD15 haplotypes were observed in our population [CG(-): 89.8%, CGC: 3.5%, CC(-): 1.6%, TG(-): 5.1%]. After stratifying the different haplotypes into diplotypes (wild type: CG(-)/CG(-), n=284, mutated haplotype, n=68) we found a significant association with all-cause and cardiovascular mortality, also after adjusting to different covariates, and (only) in univariate analysis with graft survival. In conclusion, we found different effects of the NOD2/CARD15 haplotypes on disorders, like cardiovascular and all-cause mortality,which may be considered at least in part as chronic inflammation-driven. Further studies are needed to confirm and work out the association between these disorders and the NOD2/CARD15 haplotypes.

CD44v7 ligation downregulates the inflammatory immune response in Crohn's disease patients by apoptosis induction in mononuclear cells from the lamina propria

Deletion of exon CD44v7 abrogates experimental colitis by apoptosis induction in intestinal mononuclear cells. Here we show that CD44v7 expression was upregulated upon CD40 ligation in human mononuclear cells, and examined whether ligation of CD44v7 also affects activation and apoptosis in lamina propria mononuclear cells (LPMC) from Crohn's disease (CD) patients. Thirty five patients with chronic inflammatory bowel disease (IBD), fourteen controls and four patients with diverticulitis were evaluated. CD44v7 was upregulated predominantly in the inflamed mucosa of CD patients. Furthermore, incubation with an anti-CD44v7 antibody induced apoptosis in LPMC isolated from inflamed mucosa of CD patients, but not from non-inflamed mucosa, from patients with ulcerative colitis (UC) or from normal controls. CD40 ligation and simultaneous incubation with anti-CD44v7 significantly downregulated CD80 in dendritic cells, thus inhibiting a critical second signal for naive T-cell activation. The apoptotic signal was mediated via the intrinsic mitochondrial pathway with decreased Bcl-2 and increased 7A6 (a mitochondrial membrane protein) expression. It was Fas independent and required caspases-3 and -9 activation. The process is highly specific for macrophage activation via CD40. These findings point to a novel mechanism of apoptosis induction in CD patients mediated by CD44v7 ligation.

IL-22 induces lipopolysaccharide-binding protein in hepatocytes: a potential systemic role of IL-22 in Crohn's disease

Crohn's disease (CD) is a common, chronic, inflammatory bowel disease characterized by intestinal infiltration of activated immune cells and distortion of the intestinal architecture. In this study, we demonstrate that IL-22, a cytokine that is mainly produced by activated Th1 and Th17 cells, was present in high quantities in the blood of CD patients in contrast to IFN-gamma and IL-17. In a mouse colitis model, IL-22 mRNA expression was elevated predominantly in the inflamed intestine but also in the mesenteric lymph nodes. IL-22BP, the soluble receptor for IL-22, demonstrated an affinity to IL-22 that was at least 4-fold higher than its membrane-bound receptor, and its strong constitutive expression in the intestine and lymph nodes was decreased in the inflamed intestine. To investigate the possible role of systemic IL-22 in CD, we then administered IL-22 to healthy mice and found an up-regulation of LPS-binding protein (LBP) blood levels reaching concentrations known to neutralize LPS. This systemic up-regulation was associated with increased hepatic but not renal or pulmonary LBP mRNA levels. IL-22 also enhanced the secretion of LBP in human primary hepatocytes and HepG2 hepatoma cells in vitro. This increase was mainly transcriptionally regulated and synergistic with that of other LBP inducers. Finally, elevated LBP levels were detected in CD patients and the mouse colitis model. These data suggest that systemic IL-22 may contribute to the prevention of systemic inflammation provoked by LPS present in the blood of CD patients through its induction of hepatic LBP.

RANTES/CCL5 polymorphisms as a risk factor for recurrent acute rejection

BACKGROUND

The chemokine system plays an important role in the pathogenesis of acute rejection or atherosclerosis. Three polymorphisms in the promoter region of the chemokine RANTES (-403G/A, -28G/C, In1.1T/C) are associated with a different expression of this chemokine as well as the occurrence of cardiovascular disease. Therefore, we investigated the impact of these three polymorphisms on the outcome after renal transplantation.

METHODS

In 261 patients receiving their first kidney transplant, we genotyped the RANTES promoter polymorphisms (-403G/A, -28G/C, In1.1T/C) by real-time PCR.

RESULTS

For the RANTES -403G/A and for the intronic polymorphism In1.1T/C, we found a significantly higher rate of recurrent acute rejection episodes (-403G/A: 11.1 vs. 31.0%, In1.1T/C: 11.8 vs. 33.0%). For the overall rate of acute rejection, we observed no significant differences according to the RANTES promoter polymorphisms. The other tested variables (DGF, graft survival, renal function) were not associated with one of the three polymorphisms.

CONCLUSION

Our data indicate a relevant role of RANTES in kidney transplantation, particularly for the occurrence of recurrent acute rejection. To clarify the role of the analysed polymorphisms for long-term survival, especially for the occurrence of cardiovascular events, larger studies in the future are needed.

Interleukin-22 Induces Lipopolysaccharide Binding Protein in Hepatocytes: a Potential Systemic Role of Interleukin-22 in Crohn’s Disease (B60)

Crohn’s disease (CD) is characterized by intestinal infiltration of activated immune cells and distortion of the gut architecture. Here, we demonstrate that IL-22, a cytokine that is mainly produced by activated Th1 and Th17 cells, was present in high quantities in the blood of CD patients in contrast to IFN-[gamma] and IL-17. In a mouse colitis model, IL-22 mRNA expression was elevated predominantly in the inflamed intestine but also in the mesenteric lymph nodes. Simultaneously, IL-22BP showed strong a constitutive expression in the gut and lymph nodes and was decreased in the inflamed intestine. To investigate the possible role of systemic IL-22 in CD, we administered IL-22 to healthy mice and found an up-regulation of LPS binding protein blood levels reaching concentrations known to neutralize LPS. This systemic up-regulation was associated with increased hepatic but not renal or pulmonary LBP mRNA levels. IL-22 also enhanced the secretion of LBP in hepatocytes in vitro. This increase was mainly transcriptionally regulated and synergistic with that of other LBP inducers. Finally, elevated LBP levels were detected in CD patients and the mouse colitis model. These data suggest that systemic IL-22 may contribute to the prevention of systemic inflammation provoked by LPS present in the blood of CD patients through its induction of hepatic LBP.

Five-Year Follow-up After Late Conversion From Calcineurin Inhibitors to Sirolimus in Patients With Chronic Renal Allograft Dysfunction

BACKGROUND

Chronic allograft nephropathy (CAN) is, among others, caused by nephrotoxic side effects of calcineurin inhibitors (CNI), which are to date still the mainstay of immunosuppressive therapy. Sirolimus (SIR), an immunosuppressive compound without effects on glomerular perfusion, has been used in CNI-sparing immunosuppressive protocols. We report the 5-year follow-up of a prospective, controlled conversion study from CNI to SIR in patients with moderately to severely impaired renal function.

METHODS

Twelve renal transplant recipients with moderately to severely impaired renal function (estimated glomerular filtration rate of 17 to 35 mL/min according to the MDRD formula), enrolled in a prospective, controlled 1-year pilot study were followed for 5 years.

RESULTS

Three renal grafts (25%) were lost during the 5-year follow-up. Graft loss was due to noncompliance in one patient and to CAN in the other two patients. These two patients returned to dialysis 43 and 59 months after conversion, corresponding to 86 and 75 months after transplantation, respectively. Six of nine patients had a stable or even better renal function compared to the baseline. The lipid profile increased initially, but then remained stable over time.

CONCLUSION

Conversion of immunosuppressive therapy from CNI to SIR in patients with impaired renal function more than 1 year after transplantation is feasible and safe yielding improved renal function in the majority of patients, which was sustained at 5 years follow-up.

Conversion From Mycophenolate Mofetil to Enteric-Coated Mycophenolate Sodium in Maintenance Renal Transplant Recipients Receiving Tacrolimus: Clinical, Pharmacokinetic, and Pharmacodynamic Outcomes

BACKGROUND

Mycophenolic acid (MPA) pharmacokinetics using the mycophenolate mofetil (MMF) formulation are known to differ between patients receiving tacrolimus or cyclosporine, but only limited data exist concerning concomitant use of tacrolimus and enteric-coated mycophenolate sodium (EC-MPS).

METHODS

In this six-month, multicenter, open-label, single-arm trial, 63 maintenance renal transplant patients receiving tacrolimus were converted from mycophenolate mofetil (MMF) to EC-MPS.

RESULTS

MPA concentration-time profiles in 21 patients showed that MPA exposure was similar with MMF or EC-MPS (mean area under the curve 39.9+/-11.6 microg x h/mL versus 43.7+/-17.4 microg x h/mL at day 14 post-conversion). Median time to peak concentration was 0.5 hr with MMF and 1.5 hr with EC-MPS. Inosine monophosphate dehydrogenase (IMPDH) activity was almost identical: area under the enzyme activity time curve (AEC) was 124.2+/-32.0 nmol x h/mg prot/h with MMF and 130.3+/-36.6 nmol x h/mg prot/h with EC-MPS at 14 days post-conversion; average daytime IMPDH activity was 10.3+/-2.7 nmol/h/mg protein and 10.9+/-2.7 nmol/h/mg protein, respectively. Maximal daytime inhibition of IMPDH activity was 67% with MMF and 62% with EC-MPS at day 14. One patient (1.6%) experienced mild biopsy-proven acute rejection. No graft losses or deaths occurred. Renal function remained stable (mean calculated creatinine clearance 70.6+/-26.8 mL/min with MMF and 68.8+/-25.4 mL/min six months post-conversion). Adverse events or infections with a suspected relation to EC-MPS occurred in 12 patients (19%). Four patients discontinued EC-MPS due to adverse events or infections.

CONCLUSIONS

MMF and EC-MPS are associated with similar MPA exposure and equivalent pharmacodynamic effect. Conversion of tacrolimus-treated maintenance renal transplant patients from MMF to EC-MPS is safe and well-tolerated and does not compromise therapeutic efficacy.

Microenvironment-dependent requirement of STAT4 for the induction of P-selectin ligands and effector cytokines on CD4+ T cells in healthy and parasite-infected mice

T effector cells require selectin ligands to migrate into inflamed regions. In vitro, IL-12 promotes induction of these ligands as well as differentiation of CD4+ T cells into IFN-gamma-producing Th1 but not Th2 cells. STAT4 is strongly involved in these processes. However, the presence of selectin ligands on various T effector cell subsets in vivo points to more complex regulatory pathways. To clarify the role of the IL-12/STAT4 signaling pathway, we analyzed the impact of STAT4 deficiency on the expression of P-selectin ligands (P-lig) on CD4+ T cells in vitro and in vivo, including conditions of infection. In vitro, we found significant expression of P-lig upon activation not only in the presence, but also in the absence, of IL-12, which was independent of STAT4. TGF-beta, an alternative inducer of selectin ligands in human T cells, was not effective in murine CD4+ T cells, suggesting a role of additional signaling pathways. In vivo, a significant impact of STAT4 for the generation of P-lig+CD4+ T cells was observed for cells from peripheral lymph nodes, but not for those from spleen or lung. However, upon infection with the Th2-inducing parasite Nippostrongylus brasiliensis, P-lig expression became dependent on STAT4 signaling. Interestingly, also the frequency of IL-4-producing cells was greatly diminished in absence of STAT4. These data reveal a hitherto unknown contribution of STAT4 to the generation of Th2 cells in parasite infection and suggest that signals inducing inflammation-seeking properties in vivo vary depending on environmental conditions, such as type of organ and infection.

Effect of ACE and AT-2 inhibitors on mortality and progression to microalbuminuria in a nested case-control study of diabetic nephropathy in diabetes mellitus type 2: results from the GENDIAN study

INTRODUCTION

There is an established role of clinical risk factors such as arterial hypertension and smoking in causing cardiovascular morbidity and diabetic nephropathy (DNP). Genetic factors increase the risk for DNP. To examine the genetic risk, we initiated a case-control study with predefined follow-up examinations. We describe the study design and baseline characteristics under special consideration of comedication, and give preliminary results of the 4-year follow-up.

METHODS

We enrolled all 477 patients with DNP receiving maintenance hemodialysis in 30 centers in Southern Germany between August 1999 and January 2000. As controls, we enrolled all 482 diabetes mellitus type 2 patients without urinary microalbuminuria in two examinations on consecutive days and without other signs of renal disease in a large diabetes clinic from September 2000 to September 2001. Follow-up examinations are performed 4 and 6 years after inclusion by questionnaire and telephone interview to determine mortality and new morbidity. Controls progressing to novel DNP at follow-up, as defined by semiquantitative dipstick urinary albumin/creatinine ratio > 30 mg/g, are defined as cases in the study's nested case control component.

RESULTS

At study inclusion in cases and controls, respectively, mean age was 67.3 +/- 8.2 and 58.1 +/- 11.2 years and duration of diabetes mellitus was 15.6 +/- 9.6 (at dialysis initiation) and 11.0 +/- 8.6 years. 328 controls (of which 25 had died and 14 did not perform urinalysis) were subjected to follow-up at 4 years, at a mean of 3.5 +/- 0.8 years after inclusion. 51.2% (n = 148) of living controls remained normalbuminuric, 33.9% (n = 98) had microor macroalbuminuria, and in 14.9% (n = 43) the dipstick test was inconclusive. There was no significant difference in progression to micro- or macroalbuminuria between controls treated with ACE or AT-2 inhibitors at baseline or not. Renal function as estimated by the abbreviated MDRD formula declined from 86.8 +/- 21.0 to 82.5 +/- 22.3 ml/min/1.73 m2 (p < 0.001). The decline was significant in patients on ACE or AT-2 inhibitors at baseline and not in patients without such medication at baseline.

DISCUSSION

GENDIAN is a large case-control study designed to evaluate clinical and genetic determinants of DNP and other complications of long-standing diabetes mellitus type 2. We observed an association of ACE or AT-2 inhibitor therapy with cardiovascular comorbidity and a significant decline in renal function after a 4-year follow-up.

Complete ulcer healing as primary endpoint in studies on critical limb ischemia? A critical reappraisal

OBJECTIVES

Although complete ulcer healing is the mandatory primary efficacy criterion in current European guidelines for drug trials in critical limb ischemia (CLI), the appropriateness of this endpoint has been questioned for some time. We carried out a systematic review to assess the value of this endpoint in studies on reconstructive measures, considered to be the standard of care for CLI.

METHODS

A computerized literature search (1985-2005) was performed to track down clinical studies on endovascular and surgical interventions by using the search terms CLI and ulcer healing and their synonyms.

RESULTS

1,914 papers on revascularization in CLI were identified. Complete ulcer healing was reported in 17 studies (0.9%). Among these, there were no randomized controlled trials, five prospective cohorts on endovascular procedures, and six retrospective cohorts for endovascular and surgical procedures, respectively. If healing rates or time to ulcer healing were available, they differed greatly between the studies without consistent correlation to types of therapy.

CONCLUSIONS

In past and current literature, complete ulcer healing is not a consistently reported criterion for success of revascularization in CLI. Thus, its appropriateness for efficacy assessment of drug studies in CLI patients has to be questioned.

SDF-1 expression is elevated in chronic human renal allograft rejection

The exact mechanism of acute and chronic allograft rejection still remains unclear. The chemokine SDF-1 as mediator of allograft rejection has been under intensive investigation in liver, cardiac and bone marrow transplantation, whereas in renal transplantation, there are no reports about SDF-1 to date. This study was performed to evaluate if SDF-1 might also play an important role in human renal graft biopsies. One hundred and ninety formalin-fixed, paraffin-embedded renal allograft biopsies were included in the analysis from patients with normal renal graft morphology (according to Banff 97 classification grade 1, n = 84), with acute interstitial rejection (Banff grade 4 type I, n = 10), with acute vascular rejection (Banff grade 4 type II, n = 21), with chronic allograft nephropathy (CAN, Banff grade 5, n = 23), and without rejection but with various other lesions (Banff grade 6, n = 42). SDF-1 was localized by immunohistochemistry. In biopsies with CAN, SDF-1 expression was significantly elevated in interstitial infiltrates and infiltrating neointimal cells of arteries compared with biopsies with normal renal graft morphology. This is the first study describing a role of SDF-1 in human renal allograft rejection. We were able to demonstrate in a large number of biopsies an upregulation of SDF-1 in patients with CAN. Whether SDF-1 has pro-inflammatory or protective properties in this setting has to be evaluated in further trials.

Effect of MTHFR C677T genotype on survival in type 2 diabetes patients with end-stage diabetic nephropathy

BACKGROUND

The MTHFR C677T single nucleotide polymorphism TT genotype is associated with increased levels of plasma homocysteine and possibly an effect on cardiovascular mortality. We evaluated the effect of C677T genotype on mortality in a large end-stage renal disease (ESRD) cohort.

METHODS

C677T genotype was determined in 439 Caucasians with end-stage diabetic nephropathy (DNP) (cases) recruited from 30 dialysis centres in Southern Germany. A total of 482 type 2 diabetes patients without DNP (no microalbuminuria) at inclusion served as a genotype control collective. Patients were prospectively followed for 4 years. Primary endpoint was all-cause mortality.

RESULTS

In contrast to controls, the genotype distribution in cases was not in Hardy-Weinberg equilibrium (HWE, P = 0.003), due to a less than expected number of patients with the TT genotype. The requirements of HWE were met in cases with < 2 years dialysis therapy prior to study inclusion (n = 219). TT genotype was associated with a decreased body mass index (P = 0.002) and long diabetes duration in dialysis patients (P = 0.03). However, TT genotype was not associated with an increased risk of all-cause or cardiac mortality in the total dialysis collective or the subgroup. Also, we observed no association of MTHFR genotype with cardiovascular morbidity in cases or controls (P > 0.05), or with an increased rate of progression to novel microalbuminuria.

CONCLUSION

MTHFR 677TT genotype was significantly underrepresented in patients with ESRD in our study, but was not associated with premature mortality in these patients. We found no evidence for survival bias due to C677T genotype in the ESRD cohort, or bias due to genetically determined accelerated progression to novel microalbuminuria in the controls. However, we cannot exclude that the TT genotype protects from progression from microalbuminuria to more advanced stages of DNP, or that TT genotype is associated with premature mortality before a patient progresses to ESRD.

Detection of inflamed atherosclerotic lesions with diadenosine-5',5'''-P1,P4-tetraphosphate (Ap4A) and positron-emission tomography

Diadenosine-5',5'''-P(1),P(4)-tetraphosphate (Ap(4)A) and its analog P(2),P(3)-monochloromethylene diadenosine-5',5'''-P(1),P(4)-tetraphosphate (AppCHClppA) are competitive inhibitors of adenosine diphosphate-induced platelet aggregation, which plays a central role in arterial thrombosis and plaque formation. In this study, we evaluate the imaging capabilities of positron-emission tomography (PET) with P(2),P(3)-[(18)F]monofluoromethylene diadenosine-5',5'''-P(1),P(4)-tetraphosphate ([(18)F]AppCHFppA) to detect atherosclerotic lesions in male New Zealand White rabbits. Three to six months after balloon injury to the aorta, the rabbits were injected with [(18)F]AppCHFppA, and microPET imaging showed rapid accumulation of this radiopharmaceutical in the atherosclerotic abdominal aorta, with lesions clearly visible 30 min after injection. Computed tomographic images were coregistered with PET images to improve delineation of aortoiliac tracer activity. Plaque macrophage density, quantified by immunostaining with RAM11 against rabbit macrophages, correlated with PET measurements of [(18)F]AppCHFppA uptake (r = 0.87, P < 0.0001), whereas smooth-muscle cell density, quantified by immunostaining with 1A4 against smooth muscle actin, did not. Biodistribution studies of [(18)F]AppCHFppA in normal rats indicated typical adenosine dinucleotide behavior with insignificant myocardial uptake and fast kidney clearance. The accumulation of [(18)F]AppCHFppA in macrophage-rich atherosclerotic plaques can be quantified noninvasively with PET. Hence, [(18)F]AppCHFppA holds promise for the noninvasive characterization of vascular inflammation.

Noninvasive imaging of the coronary arteries

A reliable noninvasive imaging method for significant coronary artery stenosis would have enormous implications related to cost of diagnosis and enhanced patient safety. Cardiac motion and calcified plaques, in the past, rendered a substantial number of computed tomographic (CT) images of the coronary arteries uninterpretation. The accuracy of multidetector CT for the detection of coronary stenosis appears to have progressively improved as the imaging equipment increased from 4-slice and 16-slice to 64-slice CT. With 64-slice CT, scanning of the entire coronary artery tree is possible in 10 to 13 s. Pooled data of results of a few investigations with 64-slice CT showed that the proportion of unevaluable segments is only 4%. The sensitivity of 64-slice CT for the detection of significant (>50% or = or >50%) coronary stenosis in a patient, based on pooled data, was 97% and specificity was 91%. Regarding detection of significant stenosis in any segment, the sensitivity, based on pooled data, was 91% with 64-slice CT and specificity was 96%. In a limited number of patients, sensitivity for detection of significant stenoses in proximal segments was 100%, in mid segments it was 94%, and in distal segments sensitivity it was 80%. Multi-detector CT provides the opportunity to quantify non-calcified coronary artery plaques, which may potentially be a strong predictor of cardiac events. It was also shown to be useful for the detection of stenosis in coronary artery bypass grafts.