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Biomedical subjects

Ute Hoffmann

Publications and source records attributed to Ute Hoffmann.

11 recordsLinked to original sources

Biallelic variants in ZNF142 lead to a syndromic neurodevelopmental disorder.

Biallelic variants of the gene encoding for the zinc-finger protein 142 (ZNF142) have recently been associated with intellectual disability (ID), speech impairment, seizures, and movement disorders in nine individuals from five families. In this study, we obtained phenotype and genotype information of 26 further individuals from 16 families. Among the 27 different ZNF142 variants identified in the total of 35 individuals only four were missense. Missense variants may give a milder phenotype by changing the local structure of ZF motifs as suggested by protein modeling; but this correlation should be validated in larger cohorts and pathogenicity of the missense variants should be investigated with functional studies. Clinical features of the 35 individuals suggest that biallelic ZNF142 variants lead to a syndromic neurodevelopmental disorder with mild to moderate ID, varying degrees of delay in language and gross motor development, early onset seizures, hypotonia, behavioral features, movement disorders, and facial dysmorphism. The differences in symptom frequencies observed in the unpublished individuals compared to those of published, and recognition of previously underemphasized facial features are likely to be due to the small sizes of the previous cohorts, which underlines the importance of larger cohorts for the phenotype descriptions of rare genetic disorders.

Humans↗

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.

Animals↗

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.

Cohort Studies↗

Expression of the chemokine receptor CXCR3 in human renal allografts--a prospective study.

BACKGROUND: Mechanisms involved in the recruitment and activation of inflammatory cells during renal allograft injury are still incompletely understood. Since chemokines play pivotal roles in this process, our prospective study was performed to evaluate further the role of the chemokine receptor CXCR3. METHODS: A total of 138 biopsies were included from patients without rejection and unaltered morphology (according to Banff 97 classification grade 1, n = 49), with acute interstitial rejection (Banff grade 4 type I, n = 8), with acute vascular rejection (Banff grade 4 type II, n = 23), with chronic allograft nephropathy (Banff grade 5, n = 16), without rejection but with various other lesions (Banff grade 6, n = 36) and from pre-transplant kidneys (n = 6). The expression of CXCR3-, CD4- and CD8-positive cells was localized by immunohistochemistry and quantified by image analysis. RESULTS: CXCR3 was expressed by infiltrating inflammatory cells, but not by intrinsic renal structures. CXCR3-positive cells were found to be involved in tubulitis and vascular rejection. The area of CXCR3-positive staining was significantly larger in biopsies with acute interstitial rejection (P<0.001) and acute vascular rejection (P<0.001) as compared with normal renal graft biopsies. There was a strong morphological and numerical correlation between CXCR3 and both CD4- and CD8-positive T cells, respectively. CONCLUSIONS: A significant part of both CD4- and CD8-positive T cells express the chemokine receptor CXCR3. During renal allograft rejection, the number of these cells increases significantly at the site of injury and might be targeted by CXCR3 blocking agents.

Biomarkers↗

Expression of cyclooxygenase-1 and cyclooxygenase-2 in human renal allograft rejection-- a prospective study.

Cyclooxygenases (COX) are known to be involved in inflammatory kidney diseases. However, there are no data available about the expression of COX-1 and only preliminary reports about the expression of COX-2 in biopsies of patients undergoing acute renal allograft rejection. We conducted this prospective study to analyze the expression, distribution, and cellular localization of COX-1 and -2 and thus to elucidate the role of COX in human kidney transplantation. One hundred forty-four biopsies were included from patients without rejection and unaltered morphology (n = 60), with acute interstitial rejection (n = 7), with acute vascular rejection (n = 21), with chronic allograft nephropathy (n = 16), without rejection but with various other lesions (n = 40). COX-1 and -2 expression was localized in each biopsy by immunohistochemistry. We found a highly significant up-regulation of COX-1 in vessels and in infiltrating interstitial cells of patients with acute allograft rejection compared with biopsies with well-preserved tissue. Also, COX-2 expression was significantly elevated in infiltrating interstitial cells of biopsies with acute rejection. This is the first prospective study demonstrating a significant induction of both COX-1 and -2 in human allograft biopsies with acute rejection after renal transplantation.

Adult↗

N-acetylcysteine in the prevention of radiocontrast-induced nephropathy: clinical trials and end points.

N-acetylcysteine (NAC) has been suggested to prevent radiocontrast-induced nephropathy (RCIN) in patients with a reduced renal function. However, clinical studies have not been demonstrating this effect consistently. Also, reviews and meta-analyses dealing with the question of prevention of RCIN by NAC have been controversial. Nearly all investigators used serum creatinine as surrogate end point of their trials, and changes in serum creatinine concentrations are thought to reflect the extent of renal injury as primary outcome. In a recent study, an effect of NAC on creatinine values and estimated glomerular filtration rate without any effect on cystatin C levels has been shown in volunteers with a normal renal function. Therefore, before renal protective effects of NAC in RCIN are proposed, any direct effects of NAC on creatinine, urea, and estimated glomerular filtration rate should be addressed. In future trials, the glomerular filtration rate should preferentially be measured directly, or at least additional markers of the renal function (e.g., serum cystatin C) have to be assessed. Furthermore, additional 'hard' end points, i.e., hospital morbidity, mortality, or dialysis dependency, should be considered in the design of future studies of RCIN.

Acetylcysteine↗

The value of N-acetylcysteine in the prevention of radiocontrast agent-induced nephropathy seems questionable.

Prevention of contrast agent-induced nephropathy is of crucial importance for a number of diagnostic studies. N-Acetylcysteine (NAC) was recently reported to decrease serum creatinine levels in this setting, and its administration before radiocontrast medium administration has been widely recommended. The objective of this prospective study was to investigate whether there are effects of NAC on serum creatinine levels that are independent of alterations in GFR. Volunteers with normal renal function who did not receive radiocontrast medium were studied. Fifty healthy volunteers completed the study protocol. NAC was administered orally at a dose of 600 mg every 12 h, for a total of four doses. Surrogate markers of renal function, such as serum creatinine, urea, albumin, and cystatin C levels, were measured and estimated GFR (eGFR) was assessed immediately before the administration of NAC and 4 and 48 h after the last dose. There was a significant decrease in the mean serum creatinine concentration (P < 0.05) and a significant increase in the eGFR (P < 0.02) 4 h after the last dose of NAC. The cystatin C concentrations did not change significantly. In several studies, a protective effect of NAC on renal function after radiocontrast medium administration has been postulated. This is the first study to demonstrate an effect of NAC on creatinine levels and eGFR, surrogate markers of renal injury, without any effect on cystatin C levels. Before renoprotective effects of NAC against contrast agent-induced nephropathy are considered, the direct effects of NAC on creatinine levels, urea levels, and eGFR should be assessed.

Acetylcysteine↗

Induction of cytokines and adhesion molecules in stable hemodialysis patients: is there an effect of membrane material?

BACKGROUND/AIMS: The aim of this study was to examine the effects of a biocompatible and a nonbiocompatible hemodialysis membrane on the secretion of cytokines and their specific antagonists as well as on the expression of adhesion molecules. METHODS: A crossover study using cuprophane (CU) and polysulfone (PS) dialyzers and measurements of serum tumor necrosis factor (TNF)-alpha, soluble TNF receptors, interleukin (IL)-6, IL-6 receptor, IL-2 receptor, IL-1 receptor antagonist and the adhesion molecules intercellular adhesion molecule 1, endothelial leukocyte adhesion molecule and vascular cell adhesion molecule was performed in 19 hemodialysis patients. 44 healthy volunteers served as controls. RESULTS: All of the measured cytokines and cytokine antagonists as well as all adhesion molecules were significantly elevated in hemodialysis patients compared to controls. There was a significant increase in TNF-alpha during a dialysis session with a CU dialyzer, but only a moderate increase using a PS dialyzer. None of the other cytokines and adhesion molecules were changed during a dialysis session. We were also able to show an upregulation of adhesion molecules in dialysis patients. CONCLUSION: Our study clearly demonstrates that levels of inflammatory cytokines as well as their antagonists and adhesion molecules are elevated in patients on hemodialysis therapy. Baseline values before the start of a dialysis session did not show any differences with regard to the usage of CU or PS dialysis membranes. However, CU dialyzers led to a significantly greater stimulation of TNF-alpha during the dialysis session in comparison to PS membranes, suggesting a higher degree of bioincompatibility.

Adult↗