Association of candidate gene polymorphisms with chronic kidney disease : Results of a case-control analysis in the NEFRONA cohort

Chronic kidney disease (CKD) is a major risk factor for end-stage renal disease, cardiovascular disease and premature death. Despite classical clinical risk factors for CKD and some genetic risk factors have been identified, the residual risk observed in prediction models is still high. Therefore, new risk factors need to be identified in order to better predict the risk of CKD in the population. Here, we analyzed the genetic association of 79 SNPs of proteins associated with mineral metabolism disturbances with CKD in a cohort that includes 2,445 CKD cases and 559 controls. Genotyping was performed with matrix assisted laser desorption ionization-time of flight mass spectrometry. We used logistic regression models considering different genetic inheritance models to assess the association of the SNPs with the prevalence of CKD, adjusting for known risk factors. Eight SNPs (rs1126616, rs35068180, rs2238135, rs1800247, rs385564, rs4236, rs2248359, and rs1564858) were associated with CKD even after adjusting by sex, age and race. A model containing five of these SNPs (rs1126616, rs35068180, rs1800247, rs4236, and rs2248359), diabetes and hypertension showed better performance than models considering only clinical risk factors, significantly increasing the area under the curve of the model without polymorphisms. Furthermore, one of the SNPs (the rs2248359) showed an interaction with hypertension, being the risk genotype affecting only hypertensive patients. We conclude that 5 SNPs related to proteins implicated in mineral metabolism disturbances (Osteopontin, osteocalcin, matrix gla protein, matrix metalloprotease 3 and 24 hydroxylase) are associated to an increased risk of suffering CKD

Association of Candidate Gene Polymorphisms With Chronic Kidney Disease: Results of a Case-Control Analysis in the Nefrona Cohort

Chronic kidney disease (CKD) is a major risk factor for end-stage renal disease, cardiovascular disease and premature death. Despite classical clinical risk factors for CKD and some genetic risk factors have been identified, the residual risk observed in prediction models is still high. Therefore, new risk factors need to be identified in order to better predict the risk of CKD in the population. Here, we analyzed the genetic association of 79 SNPs of proteins associated with mineral metabolism disturbances with CKD in a cohort that includes 2, 445 CKD cases and 559 controls. Genotyping was performed with matrix assisted laser desorption ionizationtime of flight mass spectrometry. We used logistic regression models considering different genetic inheritance models to assess the association of the SNPs with the prevalence of CKD, adjusting for known risk factors. Eight SNPs (rs1126616, rs35068180, rs2238135, rs1800247, rs385564, rs4236, rs2248359, and rs1564858) were associated with CKD even after adjusting by sex, age and race. A model containing five of these SNPs (rs1126616, rs35068180, rs1800247, rs4236, and rs2248359), diabetes and hypertension showed better performance than models considering only clinical risk factors, significantly increasing the area under the curve of the model without polymorphisms. Furthermore, one of the SNPs (the rs2248359) showed an interaction with hypertension, being the risk genotype affecting only hypertensive patients. We conclude that 5 SNPs related to proteins implicated in mineral metabolism disturbances (Osteopontin, osteocalcin, matrix gla protein, matrix metalloprotease 3 and 24 hydroxylase) are associated to an increased risk of suffering CKD

Recent Developments in Thrombin-Activatable Fibrinolysis Inhibitor Research

Thrombin-activatable fibrinolysis inhibitor (TAFI) provides an important molecular link between the coagulation and fibrinolytic systems. In this review, recent major advances in TAFI research, including the elucidation of crystal structures, the development of small inhibitors and the role of TAFI in systems other than hemostasis, are described and discusse

Cerebrospinal fluid inflammatory markers in patients with Listeria monocytogenes meningitis

Background: Listeria monocytogenes meningitis is the third most common cause of bacterial meningitis and is associated with high rates of mortality and unfavorable outcome. Methods: We analyzed 101 cytokines, chemokines and complement factors in CSF of adult patients with Listeria meningitis included in a prospective cohort study and compared these biomarkers between Listeria meningitis patients and negative controls, and between Listeria meningitis patients with a favorable and an unfavorable outcome. Results: CSF was available from 26 of 62 (42%) Listeria meningitis patients and 19 negative controls. Fifteen (58%) Listeria meningitis patients had an unfavorable outcome. In Listeria meningitis CSF levels of 51 biomarkers were significantly elevated compared to negative controls after Bonferroni correction. The 11 most significantly elevated (P < .01) biomarkers of unfavorable outcome in Listeria meningitis were markers of T-cell activation (sIL-2Rα, sCD40L and IL-1), interferon-related (IFN-α2, IL-18, CX3CL1, CCL20), markers of complement activation (C3a), and endothelial growth factor related (VEGF, CXCL7). Conclusions: Our data suggest that T-cell activation, complement activation, interferon- and endothelial growth factor production are important in the immune response to Listeria meningitis, and thereby influence outcome. General significance: Our study provides target pathways for further studies in the pathophysiology of Listeria meningitis

Binding characteristics of thrombin-activatable fibrinolysis inhibitor to streptococcal surface collagen-like proteins A and B

Streptococcus pyogenes is the causative agent in a wide range of diseases in humans. Thrombin-activatable fibrinolysis inhibitor (TAFI) binds to collagen-like proteins ScIA and ScIB at the surface of S. pyogenes. Activation of TAFI at this surface redirects inflammation from a transient to chronic state by modulation of the kallikrein/kinin system. We investigated TAFI binding characteristics to ScIA/ScIB. Thirty-four overlapping TAFI peptides of 20 amino acids were generated. Two of these peptides (P18: residues G205-S221, and P19: R214-0232) specifically bound to ScIA/ScIB with high affinity, and competed in a dose-dependent manner with TAFI binding to ScIA/ScIB. In another series of experiments, the binding properties of activated TAFI (TAFIa) to ScIA/ScIB were studied with a quadruple TAF1 mutant (TAFI-IIYQ) that after activation is a 70-fold more stable enzyme than wild-type TAFIa. TAFI and TAFI-IIYQ bound to the bacterial proteins with similar affinities. The rate of dissociation was different between the proenzyme (both TAF1 and TAFI-IIYQ) and the stable enzyme TAFIa-IIYQ. TAFIa-IIYQ bound to ScIA/ScIB, but dissociated faster than TAFI-IIYQ. In conclusion, the bacterial proteins ScIA and ScIB bind to a TAR fragment encompassing residues G205-D232. Binding of TAFI to the bacteria may allow activation of TAR, whereafter the enzyme easily dissociates

C-reactive protein and natural IgM antibodies are activators of complement in a rat model of intestinal ischemia and reperfusion

Background. The role of C-reactive protein (CRP), natural immunoglobulin M (IgM), and natural IgM against phosphorylcholine (anti-Pc IgM) was investigated in relation with complement activation in a rat model of intestinal ischemia and reperfusion (II/R). The effect of Cl-esterase inhibitor (C1-Inh) on this complement activation along with other inflammatory mediators was also studied. Methods. Rats were subjected to I h of superior mesenteric artery occlusion and 3 h of reperfusion. Intravenous administration Of vehicle (human albumin) or C1-Inh (200 U/kg) was performed before (n = 8) or after ischemia (n = 8). II/R increased levels of C4b/c, CRP, IgM, anti-Pc IgM, and myeloperoxidase. activity in the intestinal homogenates anti induced vascular leakage. Results. A good correlation was observed in the intestinal homogenates between C4b/c and CRP levels. Clear depositions of C3, CRP, and IgM in intestinal tissue were demonstrated after a II/R, and a strong correlation of both CRP and IgM with complement was observed. C1-Inh administered before ischemia reduced the complement activation response after HIR, as reflected by decreased levels of C4b/c in conjunction with reduced anti-Pr IgM in the intestinal homagenates. C1-Inh also decreased leakage of albumin when administered before ischemia. C1-Inh after ischemia reduced C4b/c levels and myeloperoxidase activity in the homogenates. Conclusions. CRP and IgM depositions correlated well with local complement activation, which suggests arole of these molecules in complement activation. Furthermore, C1-Inh inhibited potentially HIR injury either administered before or after ischemia, by attenuating complement activation induced by CRP and/or natural IgM antibodie

Streptococcus pneumoniae arginine synthesis genes promote growth and virulence in pneumococcal meningitis

Streptococcus pneumoniae (pneumococcus) is a major human pathogen causing pneumonia, sepsis and bacterial meningitis. Using a clinical phenotype based approach with bacterial whole-genome sequencing we identified pneumococcal arginine biosynthesis genes to be associated with outcome in patients with pneumococcal meningitis. Pneumococci harboring these genes show increased growth in human blood and cerebrospinal fluid (CSF). Mouse models of meningitis and pneumonia showed that pneumococcal strains without arginine biosynthesis genes were attenuated in growth or cleared, from lung, blood and CSF. Thus, S. pneumoniae arginine synthesis genes promote growth and virulence in invasive pneumococcal disease

Microglial response in triggering receptor expressed on myeloid cells 2 (TREM2) knock-out mice after systemic stimulation with Escherichia coli

Background: Systemic infection is an important risk factor for delirium, associated with neurodegeneration and subsequent cognitive impairment in older people. Microglial cell response is a known key player in this process and we hypothesize that the triggering receptor expressed on myeloid cells 2 (TREM2) plays an important role in the regulation of this response. Methods: 8- to 10-week old male wild-type (WT) and TREM2 knock-out (Trem2-/-) mice were intraperitoneally inoculated with live Escherichia coli (E. coli) or saline. After inoculation, all mice were treated with ceftriaxone (an antimicrobial drug) at 12 and 24 h and were sacrificed after 2 and 3 days. Microglial response was determined by immunohistochemical staining with an ionized calcium-binding adaptor molecule 1 (Iba-1) antibody and flow cytometry. mRNA expression of pro- and anti-inflammatory mediators was measured to quantify the inflammatory response. Results: We observed increased Iba-1 positive cells number in thalamus of Trem2-/- mice at 3d after inoculation compared to WT mice (mean 120 cell/mm2 [SD 8] vs 105 cell/mm2 [SD 11]; p = 0.03). Flow cytometry showed no differences in forward scatter or expression of CD11b, CD45 and CD14 between WT and Trem2-/- mice. The brain mRNA expression levels of tumor necrosis factor alpha (TNF-α) of Trem2-/- mice at 2d were higher compared to WT mice (p = 0.003). Higher mRNA expression of interleukin 1 beta (IL-1β), Iba-1, CD11b and mitogen-activated protein kinase 1 (MAPK-1) was found in brain of WT mice at 2d compared to Trem2-/- mice (respectively p = 0.02; p = 0.001; p = 0.03 and p = 0.02). In spleen there were no differences in inflammatory mediators, between WT and Trem2-/- mice. Interpretation: Although the loss of function of TREM2 during systemic infection led to an increased number of activated microglia in the thalamus, we did not observe a consistent increase in expression of inflammatory genes in the brain. The role of TREM2 in the neuro-inflammatory response following systemic infection therefore appears to be limited

Microglial cell response in α7 nicotinic acetylcholine receptor-deficient mice after systemic infection with Escherichia coli

BACKGROUND: Development of neurodegeneration in older people has been associated with microglial cell activation triggered by systemic infection. We hypothesize that α7 nicotinic acetylcholine receptor (α7nAChR) plays an important role in regulation of this process. METHODS: 8- to 10-week-old male wild-type (WT) and α7nAChR knock-out (α7nAChR-/-) mice were intraperitoneally inoculated with live Escherichia (E.) coli or saline. After inoculation, all mice were treated with ceftriaxone (an antimicrobial drug) at 12 and 24 h and killed at 2 or 3 days. The microglial response was characterized by immunohistochemical staining with an ionized calcium-binding adaptor molecule 1 (Iba-1) antibody and flow cytometry. To quantify inflammatory response, mRNA expression of pro- and anti-inflammatory mediators was measured in brain and spleen. RESULTS: We observed no differences in Iba-1 positive cell number or morphology and flow cytometry (CD11b, CD45 and CD14) of microglial cells between WT and α7nAChR-/- mice after systemic infection. Infected α7nAChR-/- mice showed significantly higher mRNA expression in brain for tumor necrosis factor alpha (TNF-α) at day 2 and 3, interleukin 6 (IL-6) at day 2 and monocyte chemotactic protein 1 (MCP-1) and suppressor of cytokine signaling 1 (SOCS1) at day 3, there was significantly lower mRNA expression in brain for mitogen-activated protein kinase 1 (MAPK1) at day 2 and 3, high-mobility group 1 (HMGB-1) and CD11b at day 2, and deubiquitinase protein A20 (A20) at day 3 compared to infected WT mice. INTERPRETATION: Loss of function of α7nAChR during systemic infection led to an increased expression of TNF-α and IL-6 in brain after systemic infection with E. coli, but not to distinct differences in microglial cell number or morphological activation of microglia