Up-regulated renal expression of TNF-α signalling adapter proteins in lupus glomerulonephritis

Exploration of the shared gene signatures and biological mechanisms between ischemia-reperfusion injury and antibody-mediated rejection in renal transplantation

BACKGROUND

Antibody-mediated rejection (ABMR) plays a crucial role in graft loss during allogeneic renal transplantation. In renal transplantation, ischemia-reperfusion injury (IRI) is unavoidable, serves as a major contributor to acute rejection, and is linked to graft loss. However, the mechanisms underlying IRI and ABMR are unclear. Therefore, this study aimed to investigate the shared genetic characteristics and biological mechanisms between IRI and ABMR.

METHODS

Gene expressions for IRI (GSE43974) and ABMR (GSE129166 and GSE36059) were retrieved from the Gene Expression Omnibus database. The shared differentially expressed genes (DEGs) of IRI and ABMR were identified, and subsequent functional enrichment analysis was performed. Immune cell infiltration in ABMR and its relationship with the shared DEGs were investigated using the CIBERSORT method. Random forest analysis, a protein-protein interaction network, and Cytoscape were used to screen hub genes, which were subsequently subjected to gene set enrichment analysis, miRNA prediction, and transcription factors analysis. The survival analysis was performed through Kaplan-Meier curves. Finally, drug compound prediction was performed on the shared DEGs using the Drug Signature Database.

RESULTS

Overall, 27 shared DEGs were identified between the renal IRI and ABMR groups. Among these, 24 genes exhibited increased co-expression, whereas none showed decreased co-expression. The shared DEGs were primarily enriched in the inflammation signaling pathways. Notably, CD4 memory T cells were identified as potential critical mediators of IRI, leading to ABMR. Tumor necrosis factor alpha-induced protein 3 (TNFAIP3), interferon regulatory factor 1 (IRF1), and early growth response 2 (EGR2) were identified as key components in the potential mechanism that link IRI and ABMR. Patients undergoing renal transplantation with higher expression levels of TNFAIP3, IRF1, and EGR2 exhibited decreased survival rates compared to those with lower expression levels.

CONCLUSION

Inflammation is a key mechanism that links IRI and ABMR, with a potential role played by CD4 memory T cells. Furthermore, TNFAIP3, IRF1, and EGR2 are implicated in the underlying mechanism between IRI and ABMR.

Interleukin-6 and epidermal growth factor as noninvasive biomarkers of progression in chronic glomerulonephritis

Several cytokines and chemokines are involved in the pathogenesis and progressive injury of renal tissues in patients with primary chronic glomerulonephritis (CGN). The objective of this study was to determine whether the urinary excretion of interleukin-6 (IL-6), transforming growth factor β1 (TGFβ1), monocytes chemoattractant protein (MCP-1), soluble tumor necrosis factor receptor 1 (sTNFR1), and epidermal growth factor (EGF) in patients with newly recognized CGN can serve as prognostic biomarkers in patients with newly recognized CGN and whether they can be effective in predicting a progressive reduction of renal function in prospective observation. The study included 150 Caucasian patients. UIL-6, UTGFβ1, UMCP-1, UsTNFR1, and UEGF were measured using enzyme-linked immunosorbent assay (ELISA) methods (Quantikine R&D System). UIL-6, UTGFβ1, UMCP-1, and UsTNFR1 were significantly higher, yet UEGF excretion was significantly lower in nephrotic patients, in patients with estimated glomerular filtration rate (eGFR) < 60/min/1.73 m2 at presentation, as well as in the progressor (PG) subgroup. In a multivariate regression analysis basal eGFR correlated with UsTNFR1, UIL-6, and UEGF excretion, although in the follow-up, ΔeGFR (delta estimated glomerular filtration rate) significantly correlated only with UEGF excretion. A logistic regression analysis showed that the most significant independent risk factors for the deterioration of renal function with time are initial high (>11.8 pg/mgCr) UIL-6 excretion, initial low (<15.5 ng/mgCr) urinary UEGF excretion, and male gender. In patients with newly diagnosed CGN, UIL-6, and UEGF can serve as prognostic biomarkers for the progression of the disease.NEW & NOTEWORTHY Baseline high urinary interleukin-6 (IL-6) excretion and low urinary epidermal growth factor (EGF) excretion and particularly high IL-6/EGF ratio were stronger predictive factors of the progression of the deterioration of the kidney function than initial estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2 or proteinuria. In patients with newly diagnosed chronic glomerulonephritis, UIL-6 and UEGF can serve as prognostic biomarkers for the progression of the disease.

CD40 Upregulation in the Retina of Patients With Diabetic Retinopathy: Association With TRAF2/TRAF6 Upregulation and Inflammatory Molecule Expression

Purpose

CD40 is upregulated in the retinas of diabetic mice, drives pro-inflammatory molecule expression, and promotes diabetic retinopathy. The role of CD40 in diabetic retinopathy in humans is unknown. Upregulation of CD40 and its downstream signaling molecules TNF receptor associated factors (TRAFs) is a key feature of CD40-driven inflammatory disorders. We examined the expression of CD40, TRAF2, and TRAF6 as well as pro-inflammatory molecules in retinas from patients with diabetic retinopathy.

Methods

Posterior poles from patients with diabetic retinopathy and non-diabetic controls were stained with antibodies against von Willebrand factor (labels endothelial cells), cellular retinaldehyde-binding protein (CRALBP), or vimentin (both label Müller cells) plus antibodies against CD40, TRAF2, TRAF6, ICAM-1, CCL2, TNF-α, and/or phospho-Tyr783 phospholipase Cγ1 (PLCγ1). Sections were analyzed by confocal microscopy.

Results

CD40 expression was increased in endothelial and Müller cells from patients with diabetic retinopathy. CD40 was co-expressed with ICAM-1 in endothelial cells and with CCL2 in Müller cells. TNF-α was detected in retinal cells from these patients, but these cells lacked endothelial/Müller cell markers. CD40 in Müller cells from patients with diabetic retinopathy co-expressed activated phospholipase Cγ1, a molecule that induces TNF-α expression in myeloid cells in mice. CD40 upregulation in endothelial cells and Müller cells from patients with diabetic retinopathy was accompanied by TRAF2 and TRAF6 upregulation.

Conclusions

CD40, TRAF2, and TRAF6 are upregulated in patients with diabetic retinopathy. CD40 associates with expression of pro-inflammatory molecules. These findings suggest that CD40-TRAF signaling may promote pro-inflammatory responses in the retinas of patients with diabetic retinopathy.

Incorporating knowledge of disease-defining hub genes and regulatory network into a machine learning-based model for predicting treatment response in lupus nephritis after the first renal flare

BACKGROUND

Identifying candidates responsive to treatment is important in lupus nephritis (LN) at the renal flare (RF) because an effective treatment can lower the risk of progression to end-stage kidney disease. However, machine learning (ML)-based models that address this issue are lacking.

METHODS

Transcriptomic profiles based on DNA microarray data were extracted from the GSE32591 and GSE112943 datasets. Comprehensive bioinformatics analyses were performed to identify disease-defining genes (DDGs). Peripheral blood samples (GSE81622, GSE99967, and GSE72326) were used to evaluate the effect of DDGs. Single-sample gene set enrichment analysis (ssGSEA) scores of the DDGs were calculated and correlated with specific immunology genes listed in the nCounter panel. GSE60681 and GSE69438 were used to examine the ability of the DDGs to discriminate LN from other renal diseases. K-means clustering was used to obtain the separate gene sets. The clustering results were extended to data derived using the nCounter technique. The least absolute shrinkage and selection operator (LASSO) algorithm was used to identify genes with high predictive value for treatment response after the first RF in each cluster. LASSO models with tenfold validation were built in GSE200306 and assessed by receiver operating characteristic (ROC) analysis with area under curve (AUC). The models were validated by using an independent dataset (GSE113342).

RESULTS

Forty-five hub genes specific to LN were identified. Eight optimal disease-defining clusters (DDCs) were identified in this study. Th1 and Th2 cell differentiation pathway was significantly enriched in DDC-6. LCK in DDC-6, whose expression positively correlated with various subsets of T cell infiltrations, was found to be differentially expressed between responders and non-responders and was ranked high in regulatory network analysis. Based on DDC-6, the prediction model had the best performance (AUC: 0.75; 95% confidence interval: 0.44-1 in the testing set) and high precision (0.83), recall (0.71), and F1 score (0.77) in the validation dataset.

CONCLUSIONS

Our study demonstrates that incorporating knowledge of biological phenotypes into the ML model is feasible for evaluating treatment response after the first RF in LN. This knowledge-based incorporation improves the model's transparency and performance. In addition, LCK may serve as a biomarker for T-cell infiltration and a therapeutic target in LN.

Macrophages in Lupus Nephritis: Exploring a potential new therapeutic avenue

Lupus nephritis (LN) is a serious complication of systemic lupus erythematosus (SLE) that occurs in about half of patients. LN is characterized by glomerular deposition of immune complexes, leading to subendothelial, mesangial and subepithelial electron dense deposits, triggering immune cell infiltration and glomerular as well as tubulointerstitial injury. Monocytes and macrophages are abundantly present in inflammatory lesions, both in glomeruli and the tubulointerstitium. Here we discuss how monocytes and macrophages are involved in this process and how monocytes and macrophages may represent specific therapeutic targets to control LN.

Relationship between Gd-IgA1 and TNFR1 in IgA nephropathy and IgA vasculitis nephritis in children - multicenter study

AIM OF THE STUDY

To evaluate the relationship between serum Gd-IgA1 (sGd-IgA1) and serum and urine TNFR1 (sTNFR1, uTNFR1) levels as possible prognostic factors in IgA nephropathy (IgAN) and IgA vasculitis nephritis (IgAVN).

MATERIAL AND METHODS

From 299 patients from the Polish Registry of Pediatric IgAN and IgAVN, 60 children (24 IgAN and 36 IgAVN) were included in the study. The control group consisted of 20 healthy children. Proteinuria, haematuria, serum creatinine as well as IgA and C3 levels were measured and glomerular filtration rate (GFR) was calculated at onset and at the end of the follow-up. Kidney biopsy findings were evaluated using the Oxford classification. Serum Gd-IgA1 and serum and urine TNFR1 levels were measured at the end of follow-up.

RESULTS

Serum Gd-IgA1 level was significantly higher in IgAN and IgAVN patients in comparison to the control group. Urine TNFR1 was significantly higher in IgAN than in IgAVN and the control group. We did not observe any differences in sTNFR1 level between IgAN, IgAVN and control groups. We found a positive correlation between Gd-IgA1 and creatinine (r = 0.34), and negative between Gd-IgA1 and GFR (r = -0.35) at the end of follow-up. We observed a negative correlation between uTNFR1/creatinine log and albumin level and protein/creatinine ratio. We did not find any correlations between Gd-IgA1 and TNFR1.

CONCLUSIONS

The prognostic value of sGd-IgA1 in children with IgAN and IgAVN has been confirmed. TNFR1 is not associated with Gd-IgA1 and is not a useful prognostic marker in children with IgAN/IgAVN and normal kidney function.

Silencing of phospholipase C gamma 2 promotes proliferation of rat hepatocytes in vitro

The management of hepatic failure is undoubtedly difficult, and poor results have led to the search for novel therapeutic approaches. Nowadays, anti-apoptotic gene therapy is considered as an ideal approach. It has been proved that phospholipase Cγ2 (PLCγ2) is involved in the apoptosis of immune cells and tumor cells; however, whether this gene is related to hepatocyte death is still unclear. This study examined the role of PLCγ2 by inhibiting its expression in rat hepatocytes with siRNA. We also further analyzed the cellular mechanism by which the expression inhibition of PLCγ2 induces cell death. Silencing PLCγ2 gene by adenovirus vector expressing PLCγ2-targeted siRNA caused the great decline in the number of G1- and G2/M phase cells, the significant increase in the number of S phase cells, and the obvious reduction in apoptosis index. In addition, silencing PLCγ2 gene relieved the rat hepatocyte damage, such as the cell shrinkage and chromatin condensation, nuclear fragmentation. Further analysis of Ad-PLCγ2 siRNA-transfected hepatocytes demonstrated that suppression of PLCγ2 gene expression could cause the caspase dependent cell death by inhibiting the signal pathway MEKK1/MKK4/JNK1/2/c-Jun. In conclusion, these findings suggest that interference with PLCγ2 expression could relieve the inhibitory effect of PLCγ2 on hepaocyte apoptosis, thus, promote proliferation through inactivating PKCδ-mediated JNK1/2 signaling pathway.

Evaluation of abrin induced nephrotoxicity by using novel renal injury markers

Abrin is a potent plant toxin analogous to ricin that is derived from the seeds of Abrus precatorius plant. It belongs to the family of type II ribosome-inactivating proteins and causes cell death by irreversibly inactivating ribosomes through site-specific depurination. In this study we examined the in vivo nephrotoxicity potential of abrin toxin in terms of oxidative stress, inflammation, histopathological changes and biomarkers of kidney injury. Animals were exposed to 0.5 and 1.0 LD50 dose of abrin by intraperitoneal route and observed for 1, 3, and 7 day post-toxin exposure. Depletion of reduced glutathione and increased lipid peroxidation levels were observed in abrin treated mice. In addition, abrin also induced inflammation in the kidneys as observed through expression of MMP-9 and MMP-9/NGAL complex in abrin treated groups by using zymography method. Nephrotoxicity was also evaluated by western blot analysis of kidney injury biomarkers including Clusterin, Cystatin C and NGAL, and their results indicate severity of kidney injury in abrin treated groups. Kidney histology confirmed inflammatory changes due to abrin. The data generated in the present study clearly prove the nephrotoxicity potential of abrin.

Adipokines, tumor necrosis factor and its receptors in female patients with systemic lupus erythematosus

OBJECTIVES

To analyze the association of adipokines and tumor necrosis factor α (TNFα) and its receptors with characteristics of systemic lupus erythematosus (SLE) and to investigate the correlation between adipokines and the TNF system.

METHODS

One hundred and thirty-six SLE women, aged ≥18 years old, were assessed. TNFα, soluble TNFα receptors 1 (sTNFR1) and 2 (sTNFR2) and adipokines were analyzed by ELISA kits.

RESULTS

The median (IQR) of age was 41.5 (33.0-49.7) years old and of disease duration 11.3 (7.8-15.8) years. The median (IQR) of disease activity was 0 (0-4) and of damage index was 2 (1-3). Higher levels of sTNFR1 and sTNFR2 were associated with nephritis (p < 0.001 for both), and sTNFR1 (p = 0.025) and TNFα (p = 0.014) were positively associated with arthritis. Higher sTNFR1 levels were found in participants that were not using antimalarial drugs (p = 0.04). Independent correlation was found between sTNFR1 (β = 0.253; p = 0.003) and sTNFR2 (β = 0.297; p < 0.001) levels and disease activity and damage index (sTNFR1: β = 0.367; p < 0.001; sTNFR2: β = 0.335; p < 0.001). Higher adiponectin levels were independently associated with nephritis (p = 0.009) and antimalarial drugs use (p = 0.015). There was a positive correlation between leptin and sTNFR2 levels (p = 0.002) and between resistin levels and sTNFR1 (p < 0.001) and sTNFR2 (p < 0.001).

CONCLUSION

The correlation between adipokines and TNF system allows a better understanding of the role of adipokines in the inflammatory response in SLE patients.

Renal microRNA- and RNA-profiles in progressive chronic kidney disease

BACKGROUND

MicroRNAs (miRNAs) contribute to chronic kidney disease (CKD) progression via regulating mRNAs involved in renal homeostasis. However, their association with clinical outcome remains poorly understood.

MATERIALS AND METHODS

We performed miRNA and mRNA expression profiling on renal biopsy sections by qPCR (miRNA) and microarrays (mRNA) in a discovery (n = 43) and in a validation (n = 29) cohort. miRNAs differentiating stable and progressive cases were inversely correlated with putative target mRNAs, which were further characterized by pathway analysis using KEGG pathways.

RESULTS

miR-30d, miR-140-3p, miR-532-3p, miR-194, miR-190, miR-204 and miR-206 were downregulated in progressive cases. These seven miRNAs correlated with upregulated 29 target mRNAs involved in inflammatory response, cell-cell interaction, apoptosis and intra-cellular signalling. In particular, miR-206 and miR-532-3p were associated with distinct biological processes via the expression of their target mRNAs: Reduced expression of miR-206 in progressive disease correlated with the upregulation of target mRNAs participating in inflammatory pathways (CCL19, CXCL1, IFNAR2, NCK2, PTK2B, PTPRC, RASGRP1 and TNFRSF25). Progressive cases also showed a lower expression of miR-532-3p and an increased expression of target transcripts involved in apoptosis pathways (MAP3K14, TNFRSF10B/TRAIL-R2, TRADD and TRAF2). In the validation cohort, we confirmed the decreased expression of miR-206 and miR-532-3p, and the inverse correlation of these miRNAs with the expression of nine of the 12 target genes. The levels of the identified miRNAs and the target mRNAs correlated with clinical parameters and histological damage indices.

CONCLUSIONS

These results suggest the involvement of specific miRNAs and mRNAs in biological pathways associated with the progression of CKD.

Circulating Tumor Necrosis Factor α Receptors Predict the Outcomes of Human IgA Nephropathy: A Prospective Cohort Study

The circulating tumor necrosis factor receptors (TNFRs) could predict the long-term renal outcome in diabetes, but the role of circulating TNFRs in other chronic kidney disease has not been reported. Here, we investigated the correlation between circulating TNFRs and renal histologic findings on kidney biopsy in IgA nephropathy (IgAN) and assessed the notion that the circulating TNFRs could predict the clinical outcome. 347 consecutive biopsy-proven IgAN patients between 2006 and 2012 were prospectively enrolled. Concentrations of circulating TNFRs were measured using serum samples stored at the time of biopsy. The primary clinical endpoint was the decline of estimated glomerular filtration rate (eGFR; ≥ 30% decline compared to baseline). Mean eGFR decreased and proteinuria worsened proportionally as circulating TNFR1 and TNFR2 increased (P < 0.001). Tubulointerstitial lesions such as interstitial fibrosis and tubular atrophy were significantly more severe as concentrations of circulating TNFRs increased, regardless of eGFR levels. The risks of reaching the primary endpoint were significantly higher in the highest quartile of TNFRs compared with other quartiles by the Cox proportional hazards model (TNFR1; hazard ratio 7.48, P < 0.001, TNFR2; hazard ratio 2.51, P = 0.021). In stratified analysis according to initial renal function classified by the eGFR levels of 60 mL/min/1.73 m², TNFR1 and TNFR2 were significant predictors of renal progression in both subgroups. In conclusion, circulating TNFRs reflect the histology and clinical severity of IgAN. Moreover, elevated concentrations of circulating TNFRs at baseline are early biomarkers for subsequent renal progression in IgAN patients.

Circulating TNF receptors 1 and 2 are associated with the severity of renal interstitial fibrosis in IgA nephropathy

The current study aimed to examine whether the levels of TNF receptors 1 and 2 (TNFR1 and TNFR2) in serum and urine were associated with other markers of kidney injury and renal histological findings, including TNFR expression, in IgA nephropathy (IgAN). The levels of the parameters of interest were measured by immunoassay in 106 biopsy-proven IgAN patients using samples obtained immediately before renal biopsy and in 34 healthy subjects. Renal histological findings were evaluated using immunohistochemistry. The levels of serum TNFRs were higher in IgAN patients than in healthy subjects. The levels of both TNFRs in serum or urine were strongly correlated with each other (r > 0.9). Serum TNFR levels were positively correlated with the urinary protein to creatinine ratio (UPCR) and four markers of tubular damage of interest (N-acetyl-β-D-glucosaminidase [NAG], β2 microglobulin [β2m], liver-type fatty acid-binding protein [L-FABP], and kidney injury molecule-1 [KIM-1]) and negatively correlated with estimated glomerular filtration rate (eGFR). Patients in the highest tertile of serum TNFR levels showed more severe renal interstitial fibrosis than did those in the lowest or second tertiles. The tubulointerstitial TNFR2-, but not TNFR1-, positive area was significantly correlated with the serum levels of TNFRs and eGFR. Stepwise multiple regression analysis revealed that elevated serum TNFR1 or TNFR2 levels were a significant determinant of renal interstitial fibrosis after adjusting for eGFR, UPCR, and other markers of tubular damage. In conclusion, elevated serum TNFR levels were significantly associated with the severity of renal interstitial fibrosis in IgAN patients. However, the source of TNFRs in serum and urine remains unclear.

TNF-α mediates PKCδ/JNK1/2/c-Jun-dependent monocyte adhesion via ICAM-1 induction in human retinal pigment epithelial cells

Retinal inflammatory diseases induced by cytokines, such as tumor necrosis factor-α (TNF-α) are associated with an up-regulation of intercellular adhesion molecule-1 (ICAM-1) in the retinal pigment epithelial cells (RPECs). Retinal pigment epithelium (RPE) is a monolayer of epithelial cells that forms the outer blood-retinal barrier in the posterior segment of the eye, and is also implicated in the pathology of, such as neovascularization in age-related macular degeneration (AMD). However, the detailed mechanisms of TNF-α-induced ICAM-1 expression are largely unclear in human RPECs. We demonstrated that in RPECs, TNF-α could induce ICAM-1 protein and mRNA expression and promoter activity, and monocyte adhesion. TNF-α-mediated responses were attenuated by pretreatment with the inhibitor of PKCs (Ro318220), PKCδ (Rottlerin), MEK1/2 (U0126), JNK1/2 (SP600125), or AP-1 (Tanshinone IIA) and transfection with siRNA of TNFR1, TRAF2, JNK2, p42, or c-Jun. We showed that TNF-α could stimulate the TNFR1 and TRAF2 complex formation. TNF-α-stimulated JNK1/2 was also reduced by Rottlerin or SP600125. However, Rottlerin had no effect on TNF-α-induced p42/p44 MAPK phosphorylation. We observed that TNF-α induced c-Jun phosphorylation which was inhibited by Rottlerin or SP600125. On the other hand, TNF-α-stimulated ICAM-1 promoter activity was prominently lost in RPECs transfected with the point-mutated AP-1 ICAM-1 promoter plasmid. These results suggest that TNF-α-induced ICAM-1 expression and monocyte adhesion is mediated through a TNFR1/TRAF2/PKCδ/JNK1/2/c-Jun pathway in RPECs. These findings concerning TNF-α-induced ICAM-1 expression in RPECs imply that TNF-α might play an important role in ocular inflammation and diseases.

Circulating TNF receptors are significant prognostic biomarkers for idiopathic membranous nephropathy

Idiopathic membranous nephropathy (iMN) is a common cause of nephrotic syndrome in adults. A biomarker to accurately indicate the severity of iMN and predict long-term prognosis is insufficient. Here, we evaluated the clinical significance of circulating tumor necrosis factor receptors (cTNFRs) as prognostic biomarkers of iMN with nephrotic syndrome. A total of 113 patients with biopsy-proven iMN and 43 healthy volunteers were enrolled in this study. Ninety patients with iMN had nephrotic range proteinuria. Levels of cTNFRs were measured by using serum samples collected at the time of initial diagnosis. Levels of cTNFRs were higher in the patients with nephrotic syndrome than in those with subnephrotic range proteinuria or in the healthy volunteers (P for trend <0.001). Estimated glomerular filtration rate and proteinuria tended to worsen as the cTNFRs levels increased. Having a cTNFR1 level within the highest tertile was a significant risk factor for renal progression after adjustment, in comparison with the other tertiles (hazard ratio [HR], 3.39; 95% confidence interval [95% CI], 1.48-7.78; P = 0.004). The cTNFR2 level within the highest tertile also significantly increased the risk of renal progression (HR, 3.29; 95% CI, 1.43-7.54; P = 0.005). Renal tubular TNFRs expression was associated with cTNFRs level. However, the cTNFRs levels were not associated with autoantibody against phospholipase A2 receptor reactivity/levels or treatment response. This study demonstrated that cTNFRs levels at the time of initial diagnosis could predict renal progression in patients with iMN.

Association between TNF promoter -308 G>A and LTA 252 A>G polymorphisms and systemic lupus erythematosus

Tumor necrosis factor (TNF) and lymphotoxin alpha (LTA) are pivotal cytokines in the pathogenesis of systemic lupus erythematosus (SLE). To investigate the possible association of the polymorphism of the TNF promoter gene -308 and that of the LTA gene 252 with susceptibility to SLE and with phenotypic disease features in Egyptian patients. A case control study involving 100 SLE patients and 100 unrelated healthy controls. Polymerase chain reaction and restriction fragment length polymorphism methods were applied to detect genetic polymorphism. We found that TNF-308 genotype AA was significantly increase by 26 % in SLE patients compared to 10 % in the control group (p = 0.003; OR 3.16; CI 1.43-6.98) and the frequency of the A allele of the TNF promoter -308 was significantly higher in the SLE patients (42 %) than in the control subjects (24 %) (p < 0.001; OR 2.29; 95 % CI 1.49-3.52). Genotype LTA 252 GG showed a significant increase by 22 % in SLE patients compared to 6 % in the control group (p = 0.001; OR 4.42; 95 % CI 1.71-11.44), and the frequency of the G allele of the LTA was significantly higher in the SLE patients (38 %) than in the control subjects (21 %) (p < 0.001; OR 2.31; 95 % CI 1.48-3.6). Genotype (AA+GA) of TNF was significantly associated with clinical manifestations as malar rash, arthritis, oral ulcers, serositis and systemic lupus erythematosus disease activity index. Genotype (GG+GA) of LTA was significantly associated with arthritis. These results suggest that TNF and LTA genetic polymorphisms contribute to SLE susceptibility in the Egyptian population and are associated with disease characteristics. TNF-308 and LTA+252 polymorphic markers may be used for early diagnosis of SLE and early prediction of clinical manifestations, like arthritis.

Urine kidney injury molecule-1: a potential non-invasive biomarker for patients with renal cell carcinoma

BACKGROUND

KIM-1 staining is upregulated in proximal tubule-derived renal cell carcinoma (RCC) including clear renal cell carcinoma and papillary renal cell carcinoma, but not in chromophobe RCC (distal tubular tumor). This study was designed to prospectively examine urine KIM-1 level before and 1 month after removal of renal tumors.

PATIENTS AND DESIGN

A total of 19 patients were eventually enrolled in the study based on pre-operative imaging studies. Pre-operative and follow-up (1 month) urine KIM-1 levels were measured. The urine KIM-1 levels (uKIM-1) were then normalized to urine creatinine levels (uCr). Renal tumors were also stained for KIM-1 using immunohistochemical techniques.

RESULTS

The KIM-1-negative staining group included 7 cases, and the KIM-1-positive group consisted of 12 cases. The percentage of KIM-1-positive staining RCC cells ranged from 10 to 100 %, and the staining intensity ranged from 1+ to 3+. In both groups, serum creatinine levels were both significantly elevated after nephrectomy. In the KIM-1-negative group, uKIM-1/uCr remained at a similar level before (0.37 ± 0.1 ng/mg Cr) and after nephrectomy (0.32 ± 0.01 ng/mg Cr). However, in the KIM-1-positive group, elevated uKIM-1/uCr at 1.20 ± 0.31 ng/mg Cr was significantly reduced to 0.36 ± 0.1 ng/mg Cr, which was similar to the pre-operative uKIM-1/uCr (0.37 ± 0.1 ng/mg Cr) in the KIM-1-negative group.

CONCLUSION

Our small but prospective study showed significant reduction in uKIM-1/uCr after nephrectomy in the KIM-1 positive group, suggesting that urine KIM-1 may serve as a surrogate biomarker for kidney cancer and a non-invasive pre-operative measure to evaluate the malignant potential of renal masses.

Tumor necrosis factor-α: regulation of renal function and blood pressure

Tumor necrosis factor-α (TNF-α) is a pleiotropic cytokine that becomes elevated in chronic inflammatory states such as hypertension and diabetes and has been found to mediate both increases and decreases in blood pressure. High levels of TNF-α decrease blood pressure, whereas moderate increases in TNF-α have been associated with increased NaCl retention and hypertension. The explanation for these disparate effects is not clear but could simply be due to different concentrations of TNF-α within the kidney, the physiological status of the subject, or the type of stimulus initiating the inflammatory response. TNF-α alters renal hemodynamics and nephron transport, affecting both activity and expression of transporters. It also mediates organ damage by stimulating immune cell infiltration and cell death. Here we will summarize the available findings and attempt to provide plausible explanations for such discrepancies.

c-Src-dependent MAPKs/AP-1 activation is involved in TNF-α-induced matrix metalloproteinase-9 expression in rat heart-derived H9c2 cells

TNF-α plays a critical mediator in the pathogenesis of chronic heart failure contributing to cardiac remodeling and peripheral vascular disturbances. The implication of TNF-α in inflammatory responses has been shown to be mediated through up-regulation of inflammatory genes, including matrix metalloproteinase-9 (MMP-9). However, the detailed mechanisms of TNF-α-induced MMP-9 expression are largely unclear in the heart cells. Here, we demonstrated that in rat embryonic-heart derived H9c2 cells, TNF-α could induce MMP-9 mRNA expression associated with an increase in the secretion of MMP-9, determined by real-time PCR, zymography, and promoter activity assays. TNF-α-mediated responses were attenuated by pretreatment with the inhibitor of c-Src (PP1), EGFR (AG1478), PDGFR (AG1296), PI3K (LY294002), Akt (SH-5), MEK1/2 (U0126), p38 MAPK (SB202190), JNK1/2 (SP600125), or AP-1 (Tanshinone IIA) and transfection with siRNA of c-Src, EGFR, PDGFR, p110, Akt, or c-Jun. TNF-α stimulated c-Src, PDGFR, and EGFR phosphorylation, which were reduced by PP1. In addition, TNF-α-stimulated Akt phosphorylation was inhibited by PP1, AG1478, AG1296, or LY294002. We further demonstrated that TNF-α markedly stimulated p38 MAPK, p42/p44 MAPK, and JNK1/2 phosphorylation via a c-Src/EGFR, PDGFR/PI3K/Akt pathway. Finally, we showed that, in H9c2 cells, TNF-α-stimulated AP-1 promoter activity, c-Jun mRNA expression, and c-Jun phosphorylation were attenuated by PP1, AG1478, AG1296, LY294002, SB202190, SP600125, or U0126. These results suggested that TNF-α-induced MMP-9 expression is mediated through a c-Src/EGFR, PDGFR/PI3K/Akt/MAPKs/AP-1 cascade in H9c2 cells. Consequently, MMP-9 induction may contribute to cell migration and cardiovascular inflammation.

TRAF2 is upregulated in relapsing-remitting multiple sclerosis

OBJECTIVE

To elucidate the role of tumor necrosis factor (TNF) receptor signal transduction in multiple sclerosis (MS).

METHODS

We performed a cross-sectional analysis of the gene expression of TRAF2 (TNF receptor-associated factor 2) and RIP (receptor-interacting protein) in peripheral blood leukocytes of 23 relapsing-remitting (RR), 19 secondary progressive (SP) and 12 primary progressive (PP) MS patients as well as of 29 healthy controls by quantitative RT-PCR. Additionally, we monitored a subgroup of 15 RRMS patients longitudinally every 3 months over a 9-month time period.

RESULTS

TRAF2 expression was significantly elevated in RRMS patients compared to the other disease courses (p<0.005, respectively) and the control group (p<0.009). RIP expression was significantly elevated in the patient groups compared to the healthy group (phealthy-RR<0.002; phealthy-PP<0.003; phealthy-SP<0.06). Neither variable changed over the 9-month time course.

CONCLUSION

TRAF2 and RIP1 elevation in leukocytes might be interpreted as the molecular equivalent of an elevated general inflammatory activity in MS patients compared to healthy control persons. TRAF2 elevation in RRMS reinforces the concept that different pathophysiological and immunological processes sustain RRMS and SPMS or PPMS.

Tumor necrosis factor receptors: biology and therapeutic potential in kidney diseases

The major evolutionary advance represented in the human immune system is a mechanism of antigen-directed immunity in which tumor necrosis factor (TNF)-α and TNF receptors (TNFRs) play essential roles. Binding of TNF-α to the 55-kDa type I TNFR (TNFR1, TNFRSF1A, CD120a, p55) or the 75-kDa type II TNFR (TNFR2, TNFRSF1B, CD120b, p75) activates signaling pathways controlling inflammatory, immune and stress responses, as well as host defense and apoptosis. Multiple studies have investigated the role of TNFRs in the development of early and late renal failure (diabetic nephropathy, nephroangiosclerosis, acute kidney transplant rejection, renal cell carcinoma, glomerulonephritis, sepsis and obstructive renal injury). This article reviews the general characteristics, the analytical aspects and the biology of TNFRs in this domain. In addition, the potential therapeutic application of specific TNFR blockers is discussed.

Gene expression of cytokines (TNF-α, IFN-γ), serum profiles of IL-17 and IL-23 in paediatric systemic lupus erythematosus

OBJECTIVE

Paediatric systemic lupus erythematosus (pSLE) exhibits an aggressive clinical phenotype and severe complications commonly renal involvement. This could be reflective of the ongoing chronic pro-inflammatory cytokine milieu. We examined relative gene expression of tumour necrosis factor-alpha (TNF-α), interferon-γ (IFN-γ) and serum levels of interleukin-17 (IL-17) and IL-23 and their association with SLEDAI (SLE disease activity index) score and organ manifestations in pSLE.

METHODS

We enrolled 40 pSLE patients (age 5-16 years, on treatment) and 20 age-matched healthy controls. Relative gene expression levels of IFN-γ and TNF-α in the peripheral blood were determined by quantitative real-time reverse transcriptase polymerase chain reaction (RT-PCR). β actin gene was used for normalization of gene expression. Serum levels of IL-17 and IL-23 were determined by solid phase sandwich ELISA. Statistical analysis were carried out for comparing (Mann-Whitney U test) and correlating data (Univariate, multivariate analysis and Pearson correlation test) with SLEDAI scores and clinical manifestations.

RESULTS

Over-expression of TNF-α and IFN-γ was found in 90% (36/40) and 80% (32/40) of pSLE patients, respectively. The relative gene expression of TNF-α and IFN-γ were significantly correlated with renal manifestations (p < 0.05). Further, relative expression of IFN-γ gene correlated significantly with skin manifestations and SLEDAI (p < 0.05). Serum levels of IL-17 (766.95 ± 357.83 pg/ml) and IL-23 (135.4 ± 54.23 pg/ml) in pSLE were significantly higher than in controls (IL-17, 172.7 ± 39.19 pg/ml and IL-23, 21.15 ± 10.99 pg/ml) (p < 0.05). Patients with cutaneous (p = 0.002) and haematological involvement (p = 0.003) had high serum IL-17 levels. Serum IL-17 levels correlated with SLEDAI (r = 0.447; p < 0.05).

CONCLUSIONS

In this preliminary study, we observed a persistent, strong pro-inflammatory cytokine milieu in pSLE patients which reflects ongoing inflammatory damage in different organs. The gene expression profile of these cytokines may be used for assessing organ involvement in pSLE. IL-17 may also serve as a prognostic marker in pSLE. However, longitudinal studies on treatment of naïve patients are required to corroborate these findings.

Cytokine disturbances in systemic lupus erythematosus

The pathogenesis of systemic lupus erythematosus (SLE) is complex, and the resulting disease manifestations are heterogeneous. Cytokine dysregulation is pervasive, and their protein and gene expression profiles may serve as markers of disease activity and severity. Importantly, biologic agents that target specific cytokines may represent novel therapies for SLE. Four cytokines (IL-6, TNFα, IFNα, and BLyS) are being evaluated as therapeutic targets in SLE. The present review will examine the roles of each of these cytokines in murine and human SLE, and will summarize results from clinical trials of agents that target these cytokines.

Anticytokine therapy in systemic lupus erythematosus

Systemic lupus erythematosus is a prototype of heterogeneous autoimmune disease. There have been few newly approved therapeutic agents in lupus treatment for many reasons. Several animal studies and human data have shown that many potential cytokines are related to the pathogenesis and disease activity of systemic lupus erythematosus. Cytokines are produced by many immune cell types and have variable functions in the immune system. Following the success of biological agents in the treatment of inflammatory arthritis, inflammatory bowel disease, and psoriasis, biological targeting to specific cytokines or receptor molecules is now promising in the treatment of systemic lupus erythematosus. In addition to B-cell deleting modalities, clinical trials targeting potential cytokines associated with disease pathogenesis are underway at various clinical stages. Among potential cytokines, targeting agents against B-cell activating factor and interferon-alpha are in the most advanced stage, and belimumab (anti-B-cell activating factor antibody) could be the first biological agent approved in the treatment of systemic lupus erythematosus. Anti-tumor necrosis factor was tried with some success, but with a potential risk of infection in a small number of patients. In this review, we discuss the rationale for anticytokine therapies and review agents currently in clinical trials, and those that could be developed in the near future for systemic lupus erythematosus. We present the results mostly from published trials and data from http://clinicaltrials.gov/ct2/

IgG anti-pentraxin 3 antibodies in systemic lupus erythematosus

OBJECTIVE

To evaluate the prevalence and correlates of anti-pentraxin 3 (PTX3) antibodies in systemic lupus erythematosus (SLE).

METHODS

Serum samples from 130 patients with SLE, 130 age- and sex-matched healthy subjects and 130 patients with other autoimmune rheumatic diseases (oARD) were analysed by home-made ELISAs using as substrate human recombinant PTX3 and two peptides, PTX3_1 and PTX3_2, obtained from the complete protein, identified as potential antigenic sites using the Lasergene DNA program (DNA Star). Inhibition tests were performed to evaluate potential interferences between bovine serum albumin or C-reactive protein and anti-PTX3 or anti-PTX3 peptides, and between antigens and antibodies. Statistical analysis was performed using receiving operating characteristics curves, the Fisher exact test, two-tailed t test and Pearson correlations.

RESULTS

Patients with SLE had higher levels and prevalence of anti-PTX3, anti-PTX3_1 and anti-PTX3_2 antibodies than patients with oARD or healthy controls (p<0.001 for all). No differences were observed between patients with oARD and healthy controls. A correlation was found between anti-PTX3 and anti-PTX3_2 antibodies (r=0.615, p<0.001). No association was observed between these antibodies and disease activity. Univariate and multivariate analyses showed that anti-PTX3 and anti-PTX3_2 antibody levels and prevalence were higher in patients without glomerulonephritis and in patients positive for antiphospholipid antibody. All inhibition tests were negative apart from PTX3 against anti-PTX3 antibody or, to a lesser extent, against anti-PTX3_2 antibody, and PTX3_2 against anti-PTX3_2 antibody, all in a dose-dependent manner.

CONCLUSIONS

Anti-PTX3 antibodies are significantly prevalent in patients with SLE where they might provide protection from renal involvement. The antigenic properties of PTX3_2 peptide are similar to those of PTX3, suggesting its potential use in further analyses.

Anti-TNF-alpha therapies in systemic lupus erythematosus

Tumor necrosis factor (TNF)-α is not just a proinflammatory cytokine. It has also been proposed to be an immunoregulatory molecule that can alter the balance of T regulatory cells. Anti-TNF-α therapies have been provided clinical benefit to many patients and introduced for treating moderate to severe rheumatoid arthritis, Crohn's disease, and other chronic inflammatory disorders. However, their use also is accompanied by new or aggravated forms of autoimmunity, such as formation of autoantibodies, including antinuclear antibodies (ANAs), antidouble-stranded DNA (dsDNA) antibodies, and anticardiolipin antibodies (ACL). Systemic lupus erythematosus (SLE) is a disease with autoimmune disturbance and inflammatory damage. The role of TNF-α in human SLE is controversial. Here we review the role of TNF-α in the pathophysiological processes of SLE and the likely effects of blocking TNF-α in treatment of SLE.

Suppression of tumor necrosis factor receptor associated factor (TRAF)-2 attenuates the proinflammatory and proliferative effect of aggregated IgG on rat renal mesangial cells

Immune-complex (IC) mediated glomerulonephritis (GN) is a common cause of chronic kidney disease associated with increased levels of tumor necrosis factor (TNF)-alpha in renal cells. TNF-alpha signaling pathways involve complicated interactions between multiple proteins including TNF-receptor-associated factor (TRAF)-2. We have previously found markedly up-regulated expression of TRAF-2 in renal tissues from IC mediated lupus nephritis patients. Here we investigated the effect of TRAF-2 on inflammatory response in rat mesangial cells (MCs). The results showed that treatment with soluble aggregated IgG (AIgG) resulted in a time- and dose-dependent increase in the expression of interleukin (IL)-1beta and IL-6. Significant cell proliferation was also observed after the treatment with soluble AIgG. Knockdown TRAF-2 by siRNA significantly suppressed soluble AIgG induced up-regulation of TRAF-2, IL-1beta, and IL-6. Meanwhile the cell proliferation was inhibited and apoptotic cells were increased. It was concluded that TRAF-2 could induce the proinflammatory and proliferative effects of soluble AIgG on rat MCs. Thus, TRAF-2 may represent a future target for therapy of IC mediated GN.

Repetitive transcranial magnetic stimulation over the right dorsolateral prefrontal cortex disrupts digit span task performance

The digit span task measures the maintenance of information in short-term memory, and is one of the most widely used tests in clinical and experimental neuropsychology. Functional imaging studies have suggested a role of the right dorsolateral prefrontal cortex (DLPFC) in digit span performance. It remains unclear however, whether activation of this area is critical for task performance. Using repetitive transcranial magnetic stimulation (rTMS) over the right DLPFC in a sham-controlled design, we tested the hypothesis of the involvement of the right DLPFC in digit span task performance. We observed a significant disruption of digit span performance in healthy subjects in the real rTMS condition as compared to the sham condition. This effect of rTMS did not differ between digits forward and digits backward. Our results suggest that the right DLPFC is critical for central executive processes utilized by the digits forward and backward tasks.