Tamás Magyarlaki

Prognostic significance of high on-clopidogrel platelet reactivity after percutaneous coronary intervention: systematic review and meta-analysis.

BACKGROUND A growing number of observational studies suggest that high on-clopidogrel platelet reactivity (HPR) is associated with recurrent thrombotic events after percutaneous coronary intervention. We aimed to perform an updated systematic review and meta-analysis on the clinical relevance of HPR to summarize the available evidence and to define more precise effect estimates. METHODS Relevant observational studies published between January 2003 and February 2010 were searched that presented intent-to-treat analyses on the clinical relevance of HPR measured with an adenosine diphosphate (ADP)-specific platelet function assay. The main outcome measures were cardiovascular (CV) death, definite/probable stent thrombosis (ST), nonfatal myocardial infarction (MI), and a composite end point of reported ischemic events. The outcome parameters were pooled with the random-effect model via generic inverse variance weighting. RESULTS Twenty studies comprising a total number of 9,187 patients qualified. High on-clopidogrel platelet reactivity appeared to be a strong predictor of MI, ST, and the composite end point of reported ischemic events (odds ratios [95% CI]: 3.00 [2.26-3.99], 4.14 [2.74-6.25], and 4.95 [3.34-7.34], respectively; P < .00001 for all cases). According to the meta-analysis, patients with HPR had a 3.4-fold higher risk for CV death compared with patients with normal ADP reactivity (odds ratio 3.35, 95% CI 2.39-4.70, P < .00001). Although there were large differences in the methodology as well as in the definition of HPR between studies, the predicted risk for CV death, MI, or ST was not heterogeneous (I(2): 0%, 0%, and 12%, respectively; P = not significant for all cases). CONCLUSIONS High on-clopidogrel platelet reactivity, measured by an ADP-specific platelet function assay, is a strong predictor of CV death, MI, and ST in patients after percutaneous coronary intervention.

Invariant Vα7.2-Jα33 TCR is expressed in human kidney and brain tumors indicating infiltration by mucosal-associated invariant T (MAIT) cells

The anti-tumor response of human invariant NKT (NKT) cells is well established. A novel T cell subset, mucosal-associated invariant T (MAIT) cells, possesses similar regulatory properties to NKT cells in autoimmune models and disease. Here, we examined the clonality of four T cell subsets expressing invariant alphaTCR, including Valpha7.2-Jalpha33 of MAIT cells, in 19 kidney and brain tumors. The MAIT clonotype was identified and co-expressed with NKT clonotype in half of the tumors. In contrast, two other invariant T cell clonotypes (Valpha4 and Valpha19) were not present in tumors. Such tumors also expressed Vbeta2 and Vbeta13, the restricted TCRbeta chain of MAIT cells and the antigen-presenting molecule MR1. A high percentage of infiltrating T cells was CD8+ and expressed HLA-DR suggesting activation. Although the MAIT alphaTCR was identified in both peripheral CD56+ and CD56- subsets, infiltrating lymphocytes were CD56 negative. The clonal presence of MAIT cells in tumors correlated with the expression of pro-inflammatory cytokines but no IL-4, IL-5 and IL-10, suggesting that a pro-inflammatory subset of human MAIT cells may exist. Our data imply that a CD56- subset of MAIT cells may participate in tumor immune responses similarly to NKT cells.

Histological Findings After Colocystoplasty And Gastrocystoplasty

PURPOSE We conducted a prospective, long-term assessment of the histological changes that can occur following bladder augmentation with colon or stomach. MATERIALS AND METHODS Histological evaluations of biopsies from 44 consecutive patients undergoing augmentation (colocystoplasty in 26, gastrocystoplasty in 18) were performed. Patients underwent endoscopic assessment and tissue sampling at 2 or 4-year intervals following the initial augmentation procedure. Patients with less than 2 years of followup were excluded from the analysis. Specimens were taken from the native bladder, the augment segment (large bowel or stomach) and the anastomotic line. Sections (4 mu.) were examined using standard histological staining methods (hematoxylin and eosin and periodic acid-Schiff) and immunohistochemistry was performed for different markers of neoplasia, cellular proliferation and blood group antigens. Histological findings were correlated with the incidence of stone formation and urinary tract infection. RESULTS Group 1 consisted of 20 patients undergoing colocystoplasty who met the criteria for study inclusion. Of the patients 10 (50%) had stones, 19 (95%) had a positive urine culture and 6 had no histological changes. While no cases of malignancy were identified, other forms of pathological change were noted in 14 of the 20 patients (70%). Group 2 included 15 patients undergoing gastrocystoplasty who met the criteria for study inclusion. No stones or malignancy were identified in this group. Positive urine cultures were recorded in 2 patients (13%), no histological changes were found in 6 and 9 (60%) had pathological changes. CONCLUSIONS Periodic prospective biopsy evaluation of children who have undergone either colocystoplasty or gastrocystoplasty failed to reveal any histological evidence of malignancy after 10-year followup. However, histological evidence of a premalignant lesion 13 years after followup suggests that screening for premalignant lesions should be initiated no later than 6 to 10 years following enterocystoplasty.

Impact of genetic variants on post-clopidogrel platelet reactivity in patients after elective percutaneous coronary intervention.

AIM To determine the effect of various SNPs on post-clopidogrel platelet reactivity and clinical outcome. MATERIALS & METHODS Cytochrome 2C19 (CYP2C19) loss-of-function (LOF; *2, *3) and gain-of-function (GOF; *17) allelic variants, together with ABCB1 (3435 C→T and 2677 G→T/A) and paraoxonase-1 (PON-1; 192 Q→R) SNPs were analyzed in 189 patients after elective stent implantation who participated in a randomized, placebo-controlled trial (NCT00638326). Platelet reactivity was determined with light transmission aggregometry and vasodilator stimulated phosphoprotein phosphorylation (VASP-PRI) 12-24 h after 600 mg clopidogrel. High on-treatment platelet reactivity (HTPR) was defined according to the consensus definition (ADP 5 µM >46%; VASP-PRI>50%). RESULTS In the case of CYP2C19 genotypes, a gene-dose effect was observed in ADP reactivity with the lowest values in GOF homozygotes and the highest degree in patients carrying two LOF alleles. The odds for HTPR also increased with the number of LOF alleles. There were no significant differences in platelet reactivity according to PON-1 or ABCB1 genotypes. In multivariate analysis, the presence of a CYP2C19 LOF allele turned out to be the independent determinant of HTPR. Although the study was not powered to clinical outcome (not LOF heterozygotes), only patients with two LOF alleles had a significantly higher risk for cardiovascular death, myocardial infarction or unplanned target vessel revascularization at 1 year compared with non-LOF carriers. CONCLUSION Genetic variants in CYP2C19 have a gene-dose effect on post-clopidogrel platelet reactivity, with homozygote LOF carriers having the highest risk for HTPR and for adverse ischemic events. Neither ABCB1 nor PON-1 genotypes significantly influenced platelet reactivity or outcome.

Mice deficient in pituitary adenylate cyclase activating polypeptide (PACAP) show increased susceptibility to in vivo renal ischemia/reperfusion injury

Pituitary adenylate cyclase activating polypeptide (PACAP) is a neuropeptide with well-known cytoprotective effects. We have reported earlier that PACAP decreases mortality and the degree of tubular atrophy in a rat model of renal ischemia/reperfusion injury. Recently, we have shown that kidney cultures isolated from PACAP deficient mice show increased susceptibility to renal oxidative stress. Based on these previous studies, we raised the question whether PACAP deficient mice display increased sensitivity to in vivo kidney ischemia/reperfusion. PACAP⁻/⁻ mice underwent 45 or 60 min of renal ischemia followed by 2 weeks reperfusion. Kidneys were processed for histological analysis. Sections stained with PAS-haematoxylin were graded for the following parameters: degree of tubular dilation, Bowmanns capsule dilation, lymphocyte and macrophage infiltration, thyroidization and the disappearance of the PAS-positive glycocalyx from under the brush border. In other sets of experiments, tissue cytokine expression and the level of the endogenous antioxidant superoxide dismutase (SOD) were also determined after 60 min ischemia/reperfusion. Our results show that while intact kidneys were not different between wild-type and PACAP deficient mice, marked differences were observed in the histological structures in groups that underwent ischemia/reperfusion. PACAP deficient mice had a worse histological outcome, with significantly higher histological scores for all tested parameters. Cytokine expression was also markedly different between wild-type and PACAP deficient mice. In addition, the level of SOD was significantly lower in PACAP⁻/⁻ animals after ischemia/reperfusion. In conclusion, the lack of endogenous PACAP leads to higher susceptibility to in vivo renal ischemia/reperfusion, suggesting that PACAP has an endogenous renoprotective effect.

Renal cell carcinoma and paraneoplastic IgA nephropathy

Paraneoplastic nephropathy is rarely associated with human tumors. Little is known about the pathogenetic background of this relationship. To our knowledge, no conclusive study of the association of potentially ‘immunogenic’ renal cell carcinoma (RCC) and paraneoplastic nephropathy has been published. For this reason, we performed an immunohistochemical analysis of native resected kidneys of 60 patients with RCC, paying special attention to their pre- and postoperative records. Sixteen (27%) of the 60 tumor patients had immune complex nephropathy (11 IgA nephropathy [IgA NP] and 5 focal segmental glomerulosclerosis [FSGS]). Preoperative proteinuria and/or hematuria observed in 11 of 16 cases disappeared in 6 IgA NP patients within a 2- to 3-month follow-up after nephrectomy. Eleven of 16 tumors stained with the anti human immunoglobulin (IgA or IgM) of the same isotype as that present in glomerular immune complexes. In 3 IgA NP patients RCC-associated von Hippel-Lindau (VHL) protein and IgA staining were found simultaneously in the tumor and glomeruli, with the clinical and laboratory findings disappearing after nephrectomy. Immune injury of the glomeruli due to a tumor-induced antigen-antibody response was demonstrated in these 3 IgA NP patients.

Justification of 150 mg clopidogrel in patients with high on-clopidogrel platelet reactivity.

Eur J Clin Invest 2012; 42 (4): 384–392

Membrane attack complex and membrane cofactor protein are related to tubulointerstitial inflammation in various human glomerulopathies

Immunohistochemical analysis of the membrane attack complex (MAC) and the membrane cofactor protein (MCP) was performed on the tubuli and cortical vessels of 46 kidney biopsies with various types of human glomerulopathies. Irrespective of the type of glomerulopathy, significant correlations between tubular MAC and interstitial lymphomonocyte infiltration (p < 0.001) and interstitial volume (p < 0.02) were found. Tubular MCP was significantly overexpressed at the site of MAC deposition (p < 0.002). There was no correlation between the vascular MAC and MCP and tubulointerstitial lesions. Since tubular MAC is deposited in inflamed areas of tubulointerstitium, we propose that MAC might contribute to the development of tubulointerstitial inflammatory processes in human glomerulopathies. MCP as a regulatory factor in the tubulointerstitium might abrogate further tissue damage and cell-stimulatory effects of the MAC.

Activated platelet-derived microparticle numbers are elevated in patients with severe fungal (Candida albicans) sepsis

Background The treatment of severe sepsis highly depends on the identification of bacteria or fungi from blood and/or other body materials. Although widely available blood culturing and risk assessment scores are not completely reliable, current guidelines do not recommend the wide empirical use of antifungal medications based on questionable benefit or possible side-effects. We aimed to test whether platelet-derived microparticle (MP) measurements can improve the early detection of the infective agent behind sepsis. Methods Thirty-three consecutive severe septic patients from our university intensive care unit were included in our prospective study. MP number and surface antigen characteristics were followed by flow cytometry on days 1 (admission), 3 and 5. For microbiological identification, various specimens were collected on admission and in case of overall status deterioration. Results On admission, septic patients showed elevated annexin V and constitutive platelet marker (CD41)-positive MP numbers compared with volunteers. Mixed fungal septic patients showed significantly elevated annexin V and CD41-positive particle numbers on day 1 (P < 0.05) compared with the non-fungal septic group. Adhesive platelet marker (CD42a) harbouring vesicles were negligible in the non-fungal group, while fungal septic patients showed significantly elevated numbers in all measurements (P < 0.01). Particles from activated platelets (PAC1) had elevated numbers in the first and fifth study days compared with non-fungal septic patients (P < 0.05). Conclusions The measurement of CD42a- and PAC1-positive microparticles may provide important additional information which can help to improve the early instalment of antifungal therapy of severe septic patients.

IMMUNOHISTOCHEMISTRY OF COMPLEMENT RESPONSE ON HUMAN RENAL CELL CARCINOMA BIOPSIES

The goal of the study was to characterize the complement humoral and cellular antitumor responses on primary renal cell carcinoma biopsies. As an original observation, complement activation was found on 11/22 cases. Classical complement pathway activation was characterized by tumor C1q complement protein and IgG deposition (5/22 cases). Alternative or nonimmune complement pathway activation was seen as tissue deposition of C3 (6/22 cases). The membrane attack complex was present in cases with alternative complement pathway activation at the sites of tumor necrosis. Renal cell carcinomas with complement activation overexpressed at least one of the complement regulatory factors (membrane cofactor protein, decay accelerating factor, membrane attack complex inhibitor) and major histocompatibility complex class II molecules. Tumor infiltrating lymphocytes were present in most of the renal cell carcinomas with complement activation (8/11). However, the number of tumor-infiltrating lymphocytes was correlated with the intensity of major histocompatibility complex-ll expression in 18/22 cases. Detection of complement activation and immune cell infiltrates on renal cell carcinoma primary biopsies may serve as a new predictive factor for immunotherapy.