Transcriptional and post-transcriptional regulation of complement factor I (CFI) gene expression in Hep G2 cells by interleukin-6

Predicting physiological aging rates from a range of quantitative traits using machine learning

It is widely thought that individuals age at different rates. A method that measures “physiological age” or physiological aging rate independent of chronological age could therefore help elucidate mechanisms of aging and inform an individual’s risk of morbidity and mortality. Here we present machine learning frameworks for inferring individual physiological age from a broad range of biochemical and physiological traits including blood phenotypes (e.g., high-density lipoprotein), cardiovascular functions (e.g., pulse wave velocity) and psychological traits (e.g., neuroticism) as main groups in two population cohorts SardiNIA (~6,100 participants) and InCHIANTI (~1,400 participants). The inferred physiological age was highly correlated with chronological age (R2 > 0.8). We further defined an individual’s physiological aging rate (PAR) as the ratio of the predicted physiological age to the chronological age. Notably, PAR was a significant predictor of survival, indicating an effect of aging rate on mortality. Our trait-based PAR was correlated with DNA methylation-based epigenetic aging score (r = 0.6), suggesting that both scores capture a common aging process. PAR was also substantially heritable (h2~0.3), and a subsequent genome-wide association study of PAR identified significant associations with two genetic loci, one of which is implicated in telomerase activity. Our findings support PAR as a proxy for an underlying whole-body aging mechanism. PAR may thus be useful to evaluate the efficacy of treatments that target aging-related deficits and controllable epidemiological factors.

C3 glomerulopathy associated to multiple myeloma successfully treated by autologous stem cell transplant

A 32-year-old male presented with advanced renal failure and nephrotic proteinuria due to lambda light chain multiple myeloma. Renal biopsy showed a proliferative glomerulonephritis with isolated C3 deposits. Renal recovery was obtained after chemotherapy and autologous stem cell transplant. We review previously described cases of C3 glomerulopathy associated with monoclonal gammopathy.

Local expression of complement factor I in breast cancer cells correlates with poor survival and recurrence

Tumor cells often evade killing by the complement system by overexpressing membrane-bound complement inhibitors. However, production of soluble complement inhibitors in cells other than hepatocytes was rarely reported. We screened several breast cancer cell lines for expression of soluble complement inhibitor, complement factor I (FI). We also analyzed local production of FI in tissue microarrays with tumors from 130 breast cancer patients by in situ hybridization and immunohistochemistry. We found expression of FI in breast adenocarcinoma cell line MDA-MB-468 and confirmed its functional activity. Expression of FI at mRNA and protein levels was also confirmed in tumor cells and tumor stroma, both in fibroblasts and infiltrating immune cells. Multivariate Cox regression analyses revealed that high expression of FI protein in tumor cells was correlated with significantly shorter cancer-specific survival (HR 2.8; 95 % CI 1.0-7.5; p = 0.048) and recurrence-free survival (HR 3.4; 95 % CI 1.5-7.4; p = 0.002). High FI expression was positively correlated with tumor size (p < 0.001), and Nottingham histological grade (p = 0.015) and associated with estrogen and progesterone receptor status (p = 0.03 and p = 0.009, respectively). Our data show that FI is expressed in breast cancer and is associated with unfavorable clinical outcome.

Rare genetic variants in the CFI gene are associated with advanced age-related macular degeneration and commonly result in reduced serum factor I levels

To assess a potential diagnostic and therapeutic biomarker for age-related macular degeneration (AMD), we sequenced the complement factor I gene (CFI) in 2266 individuals with AMD and 1400 without, identifying 231 individuals with rare genetic variants. We evaluated the functional impact by measuring circulating serum factor I (FI) protein levels in individuals with and without rare CFI variants. The burden of very rare (frequency <1/1000) variants in CFI was strongly associated with disease (P = 1.1 × 10⁻⁸). In addition, we examined eight coding variants with counts ≥5 and saw evidence for association with AMD in three variants. Individuals with advanced AMD carrying a rare CFI variant had lower mean FI compared with non-AMD subjects carrying a variant (P < 0.001). Further new evidence that FI levels drive AMD risk comes from analyses showing individuals with a CFI rare variant and low FI were more likely to have advanced AMD (P = 5.6 × 10⁻⁵). Controlling for covariates, low FI increased the risk of advanced AMD among those with a variant compared with individuals without advanced AMD with a rare CFI variant (OR 13.6, P = 1.6 × 10⁻⁴), and also compared with control individuals without a rare CFI variant (OR 19.0, P = 1.1 × 10⁻⁵). Thus, low FI levels are strongly associated with rare CFI variants and AMD. Enhancing FI activity may be therapeutic and measuring FI provides a screening tool for identifying patients who are most likely to benefit from complement inhibitory therapy.

Recovery of renal function succeeding stem cell transplant: a case of C3 Glomerulonephiritis secondary to monoclonal gammopathy

Membranoproliferative glomerulonephritis (MPGN) and C3 glomerulonephritis (C3 GN) can be secondary to monoclonal gammopathy and multiple myeloma. MPGN Type 1 is caused by activation of the classical pathway by immune complex formation, and C3 GN results from abnormalities in the alternative pathway of complement. In previously reported cases of MPGN and C3 GN secondary to monoclonal gammopathy/multiple myeloma, renal outcome has been poor. Here, we present the first patient, to our knowledge, who showed full renal recovery and normalization of the complement system after chemotherapy and stem cell transplantation.

Activation of innate anti-viral immune response genes in symptomatic benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is the most common urologic disease in men over age 50. Symptoms include acute urinary retention, urgency to urinate and nocturia. For patients with severe symptoms, surgical treatment is used to remove the affected tissue. Interestingly, the presence of histologic BPH does not always correlate with symptoms. The molecular basis of symptomatic BPH and how it differs from asymptomatic BPH is unknown. Investigation into the molecular players involved in symptomatic BPH will likely give insight into novel therapeutic, and potentially preventative, targets. We determined the expression of genes involved in the innate anti-viral immune response in tissues from patients undergoing surgery to alleviate the symptoms of BPH, and compared the results with prostate tissue with histologic BPH, but from patients with few urinary issues (asymptomatic BPH). We found that expression of complement factor I, apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like protein 3G, oligoadenylate synthetase 2 and interferon-induced tetratricopeptide 1, four genes whose protein products are involved in the innate anti-viral immune response, was significantly transcriptionally upregulated in symptomatic BPH. Additionally, we observe hypomethylation and concomitant expression of ancient retroviral-like sequences, the long interspersed nuclear element 1 retrotransposons, in symptomatic BPH when compared with normal prostate tissue. These findings merit further investigation into the anti-viral immune response in symptomatic BPH.

Transcriptional control of genes for soluble complement cascade regulatory proteins

The complement cascade of the immune system is an important mediator of the inflammatory response to infection; however it is crucial that this pathway is tightly regulated to prevent uncontrolled activation, which can lead to damage to host tissues. The complement system has many regulators that control activation; both membrane-bound and soluble factors. This review will focus on what is currently known about the transcriptional regulation of the soluble complement regulatory genes C1-inhibitor, complement factor I, complement factor H and C4-binding protein. The absence or mutation of these regulators is all associated with specific disease, and yet their contribution to disease is often poorly understood. It is through full understanding of these genes that we can comprehend the diseases with which they are implicated, and thus prove why knowledge of the transcriptional regulation of these genes is valuable.

Non-small cell lung cancer cells produce a functional set of complement factor I and its soluble cofactors

The complement system is important for protection from invading pathogens, removal of waste products and guidance of the immune response. Furthermore, complement can be also targeted to cancer cells. However, membrane-bound inhibitors over-expressed by certain types of tumor cells restrict the cytotoxic activity of complement. Herein we report that non-small cell lung cancer (NSCLC) cells produce soluble complement inhibitors factor I (FI) and C4b-binding protein (C4BP). FI is a serine protease capable of degrading the activated complement components C3b and C4b, whilst C4BP acts as its cofactor. Furthermore, NSCLC cells express membrane-bound regulators and shed membrane cofactor protein (MCP), which shares cofactor function with C4BP. Secretion of FI from NSCLC cells was higher than previously reported for any non-hepatic source and FI produced by these cells could efficiently support cleavage of C3b and C4b. In vitro functional assays revealed that additional FI significantly decreased C3 deposition and complement-dependent lysis, particularly when cofactors were added. Our results demonstrate that soluble inhibitors produced by NSCLC cells may provide further protection from complement beyond the level ensured by membrane-bound inhibitors and, as such, contribute to the aggressive phenotype of these lung cancer cells.

Improvements in the search for potential biomarkers by proteomics: Application of principal component and discriminant analyses for two-dimensional maps evaluation

In this study, we evaluated if the application of multivariate analysis on the data obtained from two-dimensional protein maps could mean an improvement in the search for protein markers. First, we performed a classical proteomic study of the differential expression of serum N-glycoproteins in colorectal cancer patients. Then, applying principal component analysis (PCA) we assessed the utility of the 2-D protein pattern and certain subsets of spots as a tool to distinguish control and case samples, and tested the accuracy of the classification model by linear discriminant analysis (LDA). On the other hand we looked for altered spots by univariate statistics and then analysed them as a cluster by PCA and LDA. We found that those proteins combined presented a theoretical sensitivity and specificity of 100%. Finally, the spots with known protein identity were analysed by multivariate methods, finding a subgroup that behaved as the most obvious candidates for further validation trials.

C5a anaphylatoxin as a product of complement activation up-regulates the complement inhibitory factor H in rat Kupffer cells

The 155-kDa complement regulator factor H (FH) is the predominant soluble regulatory protein of the complement system. It acts as a cofactor for the factor I-mediated conversion of the component C3b to iC3b, competes with factor B for a binding site on C3b and C3(H2O) and promotes the dissociation of the C3bBb complex. The primary site of synthesis is the liver, i.e. FH-specific mRNA and protein were identified in both hepatocytes (HC) and Kupffer cells (KC). Previous studies in rat primary HC and KC had shown that the proinflammatory cytokine IFN-gamma influences the balance between activation and inhibition of the complement system through up-regulation of the inhibitory FH. In this study we show that C5a, as a product of complement activation, stimulates the expression of FH-specific mRNA and protein in KC and thus induces a negative feedback. Quantitative-competitive RT-PCR showed an approximate threefold C5a-induced up-regulation of FH. ELISA analyses revealed a corresponding increase in FH protein in the supernatants of KC. The up-regulation of FH was completely inhibited by the C5a-blocking monoclonal antibody 6-9F. Furthermore, an involvement of LPS and IFN-gamma was excluded, which strongly indicates a direct effect of C5a on the expression of FH in KC.

The First Fluorescent Diboronic Acid Sensor Specific for Hepatocellular Carcinoma Cells Expressing Sialyl Lewis X

Carbohydrate antigens with subterminal fucosylation have been implicated in the development and progression of several cancers, including hepatocellular carcinoma (HCC). Fluorescent sensors targeting fucosylated carbohydrate antigens could potentially be used for diagnostic and other applications. We have designed and synthesized a series of 26 diboronic acid compounds as potential fluorescent sensors for such carbohydrates. Among these compounds, 7q was able to fluorescently label cells expressing high levels of sLex (HEPG2) within a concentration range of 0.5 to 10 microM. This compound (7q) did not label cells expressing Lewis Y (HEP3B), nor cells without fucosylated antigens (COS7). This represents the first example of a fluorescent compound labeling cells based on cell surface carbohydrate structures.

Molecular characterization of homozygous hereditary factor I deficiency

We have studied the molecular basis of factor I (fI) deficiency in two Brazilian sisters from a consanguineous family. By reverse transcription-polymerase chain reaction we observed that all fI cDNA amplified products from one sister had the same size as those of normal cDNA, however, they were significantly less intense. Sequencing analysis of subcloned cDNA revealed a dinucleotide insertion (AT) between positions 1204 and 1205 in the 11th exon that creates a stop codon 13 bp downstream of the insertion site. Genomic DNA sequencing and heteroduplex analysis confirmed that both probands are homozygous for this mutation, whereas their parents are heterozygous. The stop codon and the diminished amounts of fI cDNA could indicate increased fI mRNA instability, perhaps due to a mechanism of nonsense-mediated decay. This hypothesis is consistent with our observation that treatment with the translation inhibitor cycloheximide stabilized fI mRNA expression in proband's fibroblasts.

Transcriptional modulation of the human complement factor I gene in Hep G2 cells by protein kinase C activation

This study examined the role of the protein kinase C (PKC) signalling pathway in the regulation of expression of human complement factor I (CFI) gene. The production of CFI by Hep G2 cells was enhanced in a dose- and time-dependent fashion by 12-O-tetradecanoyl-1,2-phorbol 13-acetate (TPA), a potent PKC activator. 4Alpha-phorbol didecanoate, an inactive phorbol ester, had no effect on CFI synthesis. The TPA-dependent increase in CFI secretion was correlated with an increase in CFI mRNA levels. Forskolin, a cAMP-inducing agent, augmented the TPA response. W7, an inhibitor of protein kinase A and genistein, an inhibitor of protein tyrosine kinase(s) both did not prevent the increase in CFI expression mediated by TPA. However, calphostin C, a specific inhibitor of PKC, abolished the TPA-induced increase in CFI mRNA levels. Down regulation of intracellular PKC levels by prior exposure of Hep G2 cells to a high concentration of TPA also blocked the increase in CFI mRNA levels induced by TPA suggesting that the TPA effects were mediated via activation of PKC. mRNA decay studies indicated that the half-life of CFI mRNA in TPA-induced cells was not significantly different from control. Nuclear run-on transcriptional assays on the other hand demonstrated that whereas the CFI gene is transcribed under basal conditions in Hep G2 cells, TPA induced a 3-4 fold increase in the transcription rate of CFI gene in 24 h. The transcription rate of GAPDH gene did not change, indicating that the effects were not general on gene transcription. Transient transfections of Hep G2 cells with chloramphenicol acetyltransferase reporter gene (CAT) constructs containing a series of sequential 5' deletions of the CFI promoter and CAT assays showed that the sequence between -136 and -130, containing an AP-1 consensus sequence (TGAGTCA) was required for the TPA response. This observation was substantiated by the finding that mutation of this AP-1 site to TttaTCA or TtAtcCA abolished the TPA responsiveness. The enhancement of the activity of transfected chimeric CAT constructs by TPA was abrogated by calphostin C and by pyrrolidine dithiocarbamate (an inhibitor of NF-kappaB and AP-1 transactivation). These results indicate that TPA regulation of CFI gene requires PKC signalling and is mediated by via a TPA response element (TRE) in the CFI promoter region located at -136/-130 and involves the transactivation of AP-1 and NF-kappaB transcription factors. We suggest that PKC may be one of the intracellular pathways that control CFI gene expression and that cellular processes (involving growth factors, hormones, cytokines etc.) that activate PKC may upregulate the expression of the CFI gene.