Gábor Firneisz

Serum Dipeptidyl Peptidase-4 Activity in Insulin Resistant Patients with Non-Alcoholic Fatty Liver Disease: A Novel Liver Disease Biomarker

Background In a cross-sectional study we studied the fasting serum DPP-4 enzymatic activity (sDPP-4) and the insulin resistance index (HOMA2-IR) in gliptin naïve patients with type 2 diabetes and in non-alcoholic fatty liver disease (NAFLD) and in healthy controls (CNTRL). Methods and Findings sDPP-4 was measured by kinetic assay in 39 NAFLD (F/M:19/20, mean age: 47.42 yrs) and 82 type 2 diabetes (F/M:48/34, 62.8 yrs) patients and 26 (F/M:14/12, 35.3 yrs) controls. Definition of T2D group as patients with type 2 diabetes but without clinically obvious liver disease created non-overlapping study groups. Diagnosis of NAFLD was based on ultrasonography and the exclusion of other etiololgy. Patients in T2D and NAFLD groups were similarly obese. 75 g CH OGTT in 39 NAFLD patients: 24-NGT, 4-IGT or IFG (“prediabetes”), 11-type 2 diabetes. HOMA2-IR: CNTRL: 1.44; T2D-group: 2.62 (p = 0.046 vs CNTRL, parametric tests); NAFLD(NGTonly): 3.23 (p = 0.0013 vs CNTRL); NAFLD(IFG/IGT/type 2 diabetes): 3.82 (p<0.001 vs CNTRL, p = 0.049 vs 2TD group). sDPP-4 activity was higher in NAFLD both with NGT (mean:33.08U/L) and abnormal glucose metabolism (30.38U/L) than in CNTRL (25.89U/L, p<0.001 and p = 0.013) or in T2D groups (23.97U/L, p<0.001 and p = 0.004). Correlations in NAFLD among sDPP-4 and ALT: r = 0.4637,p = 0.0038 and γGT: r = 0.4991,p = 0.0017 and HOMA2-IR: r = 0.5295,p = 0.0026 and among HOMA2-IR and ALT: r = 0.4340,p = 0.0147 and γGT: r = 0.4128,p = 0.0210. Conclusions The fasting serum DPP-4 activity was not increased in T2D provided that patients with liver disease were intentionally excluded. The high serum DPP-4 activities in NAFLD were correlated with liver tests but not with the fasting plasma glucose or HbA1C supporting that the excess is of hepatic origin and it might contribute to the speedup of metabolic deterioration. The correlation among γGT, ALT and serum DPP-4 activity and also between serum DPP-4 activity and HOMA2-IR in NAFLD strongly suggests that serum DPP-4 activity should be considered as a novel liver disease biomarker.

Shedding of the Interleukin-6 (IL-6) Receptor (gp80) Determines the Ability of IL-6 to Induce gp130 Phosphorylation in Human Osteoblasts

Human osteoblasts produce interleukin-6 (IL-6) and respond to IL-6 in the presence of soluble IL-6 receptor (sIL-6R), but the cell surface expression of IL-6R and the mechanism of sIL-6R production are largely unknown. Three different human osteoblast-like cell lines (MG-63, HOS, and SaOS-2) and bone marrow-derived primary human osteoblasts expressed both IL-6R and gp130 as determined by flow cytometry and immunoprecipitation. However, the membrane-bound IL-6R was nonfunctional, as significant tyrosine phosphorylation of gp130 did not occur in the presence of IL-6. Phorbol myristate acetate induced a dramatic increase of both IL-6R shedding (i.e. the production of sIL-6R) and IL-6 release in osteoblast cultures, but the cell surface expression of gp130 remained unchanged. IL-6 complexed with sIL-6R, either exogenously introduced or derived from the nonfunctional cell surface form by shedding, induced rapid tyrosine phosphorylation of gp130. This effect was inhibited by neutralizing antibodies to either sIL-6R or gp130, indicating that the gp130 activation was induced by IL-6/sIL-6R/gp130 interaction. Protein kinase C inhibitors blocked phorbol myristate acetate-induced and spontaneous shedding of IL-6R resulting in the absence of sIL-6R in the culture medium, which in turn also prevented the activation of gp130. In conclusion, human osteoblasts express cell surface IL-6R, which is unable to transmit IL-6-induced signals until it is shed into its soluble form. This unique mechanism provides the flexibility for osteoblasts to control their own responsiveness to IL-6 via the activation of an IL-6R sheddase, resulting in an immediate production of functionally active osteoblast-derived sIL-6R.

Non-alcoholic fatty liver disease and type 2 diabetes mellitus: The liver disease of our age?

Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease that might affect up to one-third of the adult population in industrialised countries. NAFLD incorporates histologically and clinically different non-alcoholic entities; fatty liver (NAFL, steatosis hepatis) and steatohepatitis (NASH-characterised by hepatocyte ballooning and lobular inflammation ± fibrosis) might progress to cirrhosis and rarely to hepatocellular cancer. NAFL increasingly affects children (paediatric prevalence is 4.2%-9.6%). Type 2 diabetes mellitus (T2DM), insulin resistance (IR), obesity, metabolic syndrome and NAFLD are particularly closely related. Increased hepatic lipid storage is an early abnormality in insulin resistant women with a history of gestational diabetes mellitus. The accumulation of triacylglycerols in hepatocytes is predominantly derived from the plasma nonesterified fatty acid pool supplied largely by the adipose tissue. A few NAFLD susceptibility gene variants are associated with progressive liver disease, IR, T2DM and a higher risk for hepatocellular carcinoma. Although not approved, pharmacological approaches might be considered in NASH patients.

Genetic rescue of chondrodysplasia and the perinatal lethal effect of cartilage link protein deficiency

The targeted disruption of cartilage link protein gene (Crtl1) in homozygous mice resulted in a severe chondrodysplasia and perinatal lethality. This raised the question of whether the abnormalities seen in Crtl1 null mice are all caused by the absence of link protein in cartilage or whether the deficiency of the protein in other tissues and organs contributed to the phenotype. To address this question we have generated transgenic mice overexpressing cartilage link protein under the control of a cartilage-specific promoter, and then these transgenic mice were used for a genetic rescue of abnormalities in Crtl1 null mice. While the overexpression of cartilage link protein resulted in no abnormal phenotype, the cartilage-specific transgene expression of link protein could completely prevent the perinatal mortality of link protein-deficient mice and, depending on the level of the link protein expression, rescue skeletal abnormalities. Although link protein was originally isolated from cartilage, we found and determined Crtl1 transcripts and corresponding proteins in every organ tested from mouse embryos to aging animals. We also identified three additional members of the link protein family, all co-localized with hyaluronic acid-binding proteoglycans in the mouse genome. The ubiquitous presence of link protein suggests a general and systemic function of link protein in the organization of extracellular matrix in a number of tissues, possibly interacting with other proteoglycans, such as versican, brevican, and neurocan.

Elevated plasma nociceptin level in patients with Wilson disease

Plasma level of nociceptin, the endogenous agonist of orphanin FQ/ORL1 receptor was found to be significantly elevated in Wilson disease patients (13.98+/-2.44pg/ml, p<0.001, n=20) compared to age-matched healthy controls (9.18+/-1.63pg/ml, n=25). Wilson disease is an autosomal recessive disorder of copper metabolism caused by mutation of the gene ATP7B leading to toxic copper accumulation in the liver and other organs such as brain, kidney and cornea. Measurements were performed by 125I-radioimmunoassay. Neither sex differences nor correlation between plasma nociceptin levels and liver function test results were found. It is suggested that elevated plasma nociceptin level found in Wilson disease patients is due to inhibition of nociceptin-inactivating Zn-metallopeptidases (aminopeptidase N (APN) and endopeptidase 24.15) by the toxic copper deposits in liver and/or brain.

Serum Dipeptidyl Peptidase IV (DPP IV, CD26) Activity in Chronic Hepatitis C

BACKGROUND DPP IV is a cell surface ectoenzyme widely distributed in the human body. It has been implicated in T-cell activation, hepatocyte-extracellular-matrix interactions and fibroblast proliferation. Furthermore, upregulated CD26 expression has been found on the surface of human hepatoma cells transfected with hepatitis C virus (HCV) c-DNA. We examined the serum DPP IV activity in a large number of patients with chronic HCV infection in a cross-sectional study. We also investigated whether the activity differs from that in controls and depends upon the response to interferon (IFN) therapy. METHODS Serum DPP IV activity was measured by microplate-based (Multiskan-Plus-MKII, Labsystem) kinetic assay in 144 patients with chronic HCV infection. Seventy-four out of 144 patients (46 non-responders, 28 responders) were formerly treated with interferon. Sixty healthy blood donors served as controls. Gly-Pro-PNA (Bachem, Torrance, USA) was used as substrate. Results are expressed in nmol/ml/min (U/l). Shapiro-Wilks test, Mann-Whitney U test and Spearman rank order correlation were used for statistical analysis. RESULTS Serum DPP IV activity was significantly higher (mean = 20.89 [s 9.6]) in patients with chronic HCV infection than in healthy controls (12.39 [2.76, P < 10(-5)]). The enzyme activities significantly differed in naive HCV-positive patients (22.2 [9.89, P < 10(-5)]) and non-responders (23.28 [9.57, P < 10(-5)]) from that in the healthy controls and also from that in responders (13.69 [4.21]). Correlation was found between DPP IV activity and AST (r = 0.44, P < 10(-5)), ALT (r = 0.44, P < 10(-5)), GGT (r = 0.41, P < 10(-5)) levels. CONCLUSION Serum DPP IV activity seems to be an indicator of HCV induced liver injury. The activity may reflect the efficacy of interferon therapy.Background: DPP IV is a cell surface ectoenzyme widely distributed in the human body. It has been implicated in T-cell activation, hepatocyte-extracellular-matrix interactions and fibroblast proliferation. Furthermore, upregulated CD26 expression has been found on the surface of human hepatoma cells transfected with hepatitis C virus (HCV) c-DNA. We examined the serum DPP IV activity in a large number of patients with chronic HCV infection in a cross-sectional study. We also investigated whether the activity differs from that in controls and depends upon the response to interferon (IFN) therapy. Methods: Serum DPP IV activity was measured by microplate-based (Multiskan-Plus-MKII, Labsystem) kinetic assay in 144 patients with chronic HCV infection. Seventy-four out of 144 patients (46 nonresponders, 28 responders) were formerly treated with interferon. Sixty healthy blood donors served as controls. Gly-Pro-PNA (Bachem, Torrance, USA) was used as substrate. Results are expressed in nmol/ml/min (U/l). Shapiro-Wilks test, Mann-Whitney U test and Spearman rank order correlation were used for statistical analysis. Results: Serum DPP IV activity was significantly higher (mean = 20.89 [s 9.6]) in patients with chronic HCV infection than in healthy controls (12.39 [2.76, P < 10-5]). The enzyme activities significantly differed in naive HCV-positive patients (22.2 [9.89, P < 10-5]) and nonresponders (23.28 [9.57, P < 10-5]) from that in the healthy controls and also from that in responders (13.69 [4.21]). Correlation was found between DPP IV activity and AST (r = 0.44, P < 10-5), ALT (r = 0.44, P < 10-5), GGT (r = 0.41, P < 10-5) levels. Conclusion: Serum DPP IV activity seems to be an indicator of HCV induced liver injury. The activity may reflect the efficacy of interferon therapy.

Disease-Associated Qualitative and Quantitative Trait Loci in Proteoglycan-Induced Arthritis and Collagen-Induced Arthritis

&NA; Two autoimmune murine models—proteoglycan (aggrecan)‐induced arthritis (PGIA) and collagen‐induced arthritis (CIA)—were developed in parent strains, F1 and F2 hybrids of major histocompatibility complex (MHC)–matched (H‐2d) BALB/c × DBA/2 and MHC‐unmatched (H‐2d/H‐2q) BALB/c × DBA/1 intercrosses. The major goal of this comparative study was to identify disease (model)‐specific (PGIA or CIA) and shared clinical and immunologic loci in 2 types of genetic intercrosses. Qualitative (binary/susceptibility) and quantitative (severity and onset) clinical trait loci were separated and analyzed independently or together with various pathophysiologic/immunologic traits, such as antigen‐specific T‐ and B‐cell responses and cytokine production. The major quantitative trait locus (QTL) was the MHC on chromosome 17, which was especially dominant in CIA. In addition, chromosomes 3, 5, 10, and × contained shared clinical loci in both models, and a total of 8 QTLs (clinical traits together with immunologic traits) were colocalized in PGIA and CIA.

Identification and quantification of disease-related gene clusters

MOTIVATION DNA microarray technology and the completion of human and mouse genome sequencing programs are now offering new avenues for the investigation of complex genetic diseases. In particular, this makes possible the study of the spatial distribution of disease-related genes within the genome. We report on the first systematic search for clustering of genes associated with a polygenic autoimmune disease. RESULTS Using a set of cDNA microarray chip experiments in two mouse models of rheumatoid arthritis, we have identified approximately 200 genes based on their expression in inflamed joints and mapped them into the genome. We compute the spatial autocorrelation function of the selected genes and find that they tend to cluster over scales of a few megabase pairs. We then identify significant gene clusters using a friends-of-friends algorithm. This approach should aid in discovering functionally related gene clusters in the mammalian genome.

Elevated serum dipeptidyl peptidase IV (CD26, EC 3.4.14.5) activity in experimental liver cirrhosis

Dipeptidyl peptidase IV (DPP IV) is a cell surface ectoenzyme widely distributed in the rat body, present on the epithelial cells of the brush border membranes (e.g. bile canaliculi) and on the surface of reactive lymphocytes and fibroblasts. DPP IV has been implicated in hepatocyte–extracellular matrix interactions, fibroblast activation and proliferation and in T‐cell activation. Aberrant DPP IV expression was found in human liver cirrhosis, and elevated serum DPP IV activity was reported in patients with primary biliary cirrhosis and chronic hepatitis C virus infection. The aim of the study was to examine serum DPP IV activity in experimental liver cirrhosis.

Extension of the CD4+Foxp3+CD25−/low regulatory T-cell subpopulation in type 1 diabetes mellitus

Abstract Regulatory T-cells (Treg) have a crucial role in limiting physiologic autoreactivity. Foxp3 is a master regulator transcription factor of Treg differentiation and active Treg cells express high levels of IL-2 receptor α-chain (CD25). The aim of our study was to assess the key markers of Treg cell function in type 1 diabetic (T1DM) and control subjects by flow cytometry. The proportion of CD25−/low cells among CD4+Foxp3+ Treg cells was higher in T1DM patients that might suggest a shifted proportion of the incomplete/reserve and the fully active (CD4+Foxp3+CD25+) Treg cell subpopulations in T1DM, similarly to other Th1-mediated autoimmune diseases. In addition to the decreased expression of CD25 and CTLA-4 in T1DM patients, a positive correlation was observed between the CD25 expression on CD4+ and the CTLA-4 expression in CD8− T-lymphocytes both in the T1DM and in the healthy control group. Our results suggest an impaired balance of CD25+ and CD25−/low Treg cells in T1DM which might reflect a decreased late phase peripheral Treg activation even in patients with a mean disease duration of more than a decade.