Sex differential impact of comorbidities in spondyloarthritis: data from COMOSPA study

OBJECTIVES

To describe and compare the prevalence of comorbidities in female and male patients with spondyloarthritis (SpA) and to assess whether comorbidities had a different impact on disease outcomes in male and female patients.

METHODS

This is a post hoc analysis of the COMOrbidities in SPondyloArthritis study. Differences in comorbidities regarding sex were assessed using logistic regression models. Comorbidities were evaluated for their impact on disease outcomes (Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Ankylosing Spondylitis Disease Activity Score (ASDAS), Bath Ankylosing Spondylitis Functional Index, European health-related quality of life questionnaire) with linear models, which included sex and comorbidity as explanatory variables and their interaction. Age and treatment with biological synthetic disease-modifying antirheumatic drugs were included as confounders.

RESULTS

We included 3982 patients with SpA (65% male, mean age 43.6 years). Male and female patients with SpA exhibited similar comorbidity profiles, except for a low prevalence of fibromyalgia in males and a higher prevalence of certain cardiovascular risk factors in males (hypertension, dyslipidaemia, renal impairment and ischaemic heart disease). Comorbidities, especially fibromyalgia, correlated with higher disease activity, decreased physical function and reduced health-related quality of life in both sexes. Some comorbidities exhibited sex-specific associations with disease outcomes. Peptic ulcers and high waist circumference had a greater impact on disease activity in females (with a higher impact in BASDAI than in ASDAS). In contrast, osteoporosis had a more pronounced effect on physical function in male patients.

CONCLUSIONS

Comorbidities exert distinct influences on disease activity, physical function and health-related quality of life in male and female patients with SpA. Understanding these sex-specific effects is crucial for improving SpA management, emphasising the importance of assessing disease activity using ASDAS when comorbidities are present to mitigate sex-related disparities in disease assessment.

Specific-cytokine associations with outcomes in knee osteoarthritis subgroups: breaking down disease heterogeneity with phenotyping

BACKGROUND

Despite existing extensive literature, a comprehensive and clinically relevant classification system for osteoarthritis (OA) has yet to be established. In this study, we aimed to further characterize four knee OA (KOA) inflammatory phenotypes (KOIP) recently proposed by our group, by identifying the inflammatory factors associated with KOA severity and progression in a phenotype-specific manner.

METHODS

We performed an analysis within each of the previously defined four KOIP groups, to assess the association between KOA severity and progression and a panel of 13 cytokines evaluated in the plasma and synovial fluid of our cohort's patients. The cohort included 168 symptomatic female KOA patients with persistent joint effusion.

RESULTS

Overall, our analyses showed that associations with KOA outcomes were of higher magnitude within the KOIP groups than for the overall patient series (all p-values < 1.30e-16) and that several of the cytokines showed a KOIP-specific behaviour regarding their associations with KOA outcomes.

CONCLUSION

Our study adds further evidence supporting KOA as a multifaceted syndrome composed of multiple phenotypes with differing pathophysiological pathways, providing an explanation for inconsistencies between previous studies focussed on the role of cytokines in OA and the lack of translational results to date. Our findings also highlight the potential clinical benefits of accurately phenotyping KOA patients, including improved patient stratification, tailored therapies, and the discovery of novel treatments.

Biological and glucocorticoids treatment impair the medium-term immunogenicity to SARS-CoV-2 mRNA vaccines in autoimmune inflammatory rheumatic diseases

BACKGROUND

This study aims to assess the sustained immunological response to the SARS-CoV-2 vaccine in patients with autoimmune inflammatory rheumatic diseases (AIRD) undergoing different treatment regimens.

METHODS

We conducted a prospective observational study involving 157 AIRD patients without prior COVID-19 infection. Treatment regimens included non-treatment or glucocorticoid-only (not-treated/GCs), non-biological drugs, biological therapy, and JAK inhibitors. All participants completed the two-dose vaccine schedule, and 110 of them received an additional booster dose. Serum samples were collected approximately 3-6 months after the second and third vaccine doses to measure antibodies against the Spike protein (antiS-AB) and neutralizing antibodies (nAB) targeting six SARS-CoV-2 variants.

RESULTS

Following the third dose, all patients exhibited a significant increase in antiS-AB (FC = 15, p < 0.0001). Patients under biological therapy had lower titres compared to the non-biological (66% decrease, p = 0.038) and the not-treated/GCs group (62% decrease, p = 0.0132), with the latter persisting after the booster dose (86% decrease, p = 0.0027). GC use was associated with lower antiS-AB levels in the biological group (87% decrease, p = 0.0124), although not statistically significant after confounders adjustment. nABs showed the highest positivity rates for the wild-type strain before (50%) and after the booster dose (93%), while the Omicron variant exhibited the lowest rates (11% and 55%, respectively). All variants demonstrated similar positivity patterns and good concordance with antiS-AB (AUCs from 0.896 to 0.997).

CONCLUSIONS

The SARS-CoV-2 vaccine booster strategy effectively elicited a sustained antibody immune response in AIRD patients. However, patients under biological therapies exhibited a reduced response to the booster dose, particularly when combined with GCs.

Metabolic and inflammatory profiles define phenotypes with clinical relevance in female knee osteoarthritis patients with joint effusion

OBJECTIVES

Osteoarthritis has been the subject of abundant research in the last years with limited translation to the clinical practice, probably due to the disease's high heterogeneity. In this study, we aimed to identify different phenotypes in knee osteoarthritis (KOA) patients with joint effusion based on their metabolic and inflammatory profiles.

METHODS

A non-supervised strategy based on statistical and machine learning methods was applied to 45 parameters measured on 168 female KOA patients with persistent joint effusion, consecutively recruited at our hospital after a monographic OA outpatient visit. Data comprised anthropometric and metabolic factors and a panel of systemic and local inflammatory markers. The resulting clusters were compared regarding their clinical, radiographic and ultrasound severity at baseline and their radiographic progression at two years.

RESULTS

Our analyses identified four KOA inflammatory phenotypes (KOIP): a group characterized by metabolic syndrome, probably driven by body fat and obesity, and by high local and systemic inflammation (KOIP-1); a metabolically healthy phenotype with mild overall inflammation (KOIP-2); a non-metabolic phenotype with high inflammation levels (KOIP-3); and a metabolic phenotype with low inflammation and cardiovascular risk factors not associated with obesity (KOIP-4). Of interest, these groups exhibited differences regarding pain, functional disability and radiographic progression, pointing to a clinical relevance of the uncovered phenotypes.

CONCLUSION

Our results support the existence of different KOA phenotypes with clinical relevance and differing pathways regarding their pathophysiology and disease evolution, which entails implications in patients' stratification, treatment tailoring and the search of novel and personalized therapies.

Roastgsa: a comparison of rotation-based scores for gene set enrichment analysis

BACKGROUND

Gene-wise differential expression is usually the first major step in the statistical analysis of high-throughput data obtained from techniques such as microarrays or RNA-sequencing. The analysis at gene level is often complemented by interrogating the data in a broader biological context that considers as unit of measure groups of genes that may have a common function or biological trait. Among the vast number of publications about gene set analysis (GSA), the rotation test for gene set analysis, also referred to as roast, is a general sample randomization approach that maintains the integrity of the intra-gene set correlation structure in defining the null distribution of the test.

RESULTS

We present roastgsa, an R package that contains several enrichment score functions that feed the roast algorithm for hypothesis testing. These implemented methods are evaluated using both simulated and benchmarking data in microarray and RNA-seq datasets. We find that computationally intensive measures based on Kolmogorov-Smirnov (KS) statistics fail to improve the rates of simpler measures of GSA like mean and maxmean scores. We also show the importance of accounting for the gene linear dependence structure of the testing set, which is linked to the loss of effective signature size. Complete graphical representation of the results, including an approximation for the effective signature size, can be obtained as part of the roastgsa output.

CONCLUSIONS

We encourage the usage of the absmean (non-directional), mean (directional) and maxmean (directional) scores for roast GSA analysis as these are simple measures of enrichment that have presented dominant results in all provided analyses in comparison to the more complex KS measures.

AB1119 GLUCOCORTICOIDS’ TREATMENT IMPAIRS THE MEDIUM-TERM IMMUNOGENIC RESPONSE TO SARS-CoV-2 mRNA VACCINES IN SYSTEMIC LUPUS ERYTHEMATOSUS PATIENTS

Background

Patients with rheumatic diseases are at an increased risk for community infections (1,2). There still exists lack of data regarding SARS-CoV-2 vaccines’ efficacy in vulnerable collectives with a compromised immune system, either due to a chronic pathology or to therapies targeting an autoimmune disease (3).

Objectives

To evaluate neutralizing antibodies (nAB) to SARS-CoV-2 vaccine after 3 to 5 months from administration in Systemic Lupus Erythematosus (SLE) patients, as a surrogate of sustained-immunological response.

Methods

This cross-sectional study compared nAB titre of 39 SLE patients and 37 Healthy individuals with no previous SARS-CoV-2 infection, who had all received two doses of a mRNA SARS-CoV-2 vaccine within the last 3 to 6 months. SLE patients included 10 Not-treated subjects, 10 patients with Hydroxychloroquine (First-Line), 10 subjects with immunosuppressive drugs (Second-Line) and 9 patients under biological treatment (Third-Line). Glucocorticoids were permitted in all patient groups. Neutralization assay were used to determine nAB titre according previously validated protocol (4).

Results

Neutralizing antibody titres were assessed for a total of 76 serum samples from 39 (51%) Lupus patients and 37 (49%) healthy Controls. Healthy individuals showed the highest levels of nAB (1638.0 titre median), which were like not treated SLE subjects (1361.5 titre median). Treated patients presented substantially lower nAB titres compared to Healthy subjects: a 73% decrease for First-Line patients (p-value = 0.0135), 56% for patients received a Second-Line treatment (p-value = 0.2218) and 72% for Third-Line treated patients (p-value = 0.0104). A multivariate analysis pointed to Glucocorticoids as the most associated factor with declining nAB levels (75% decrease, p-value = 0.0037), and the one explaining, to a large extent, the lower acquired response in treated SLE patients. Furthermore, a significant reduction in nAB titres was observed for patients treated with Rituximab compared to Healthy subjects (89% decrease, p-value= 0.0008) (Figure 1).

Figure 1.

Neutralizing antibody (nAB) titre after SARS-CoV-2 vaccination in Healthy individuals (Controls) and Systemic Lupus Erythematosus (SLE) patients under different therapy regimes. Estimations are derived from a linear model in which sex, age, time from vaccination, vaccine type and corticoids therapy were included as covariates for statistical control.

Conclusion

Medium-term response of SLE patients to SARS-CoV-2 vaccination, as measured by the titre of nABs, may be compromised by Glucocorticoids and Rituximab users. This reduced response likely translates into a higher probability of COVID-19 infection These findings might help to inform recommendations in vaccination protocols for SLE patients.

References

[1]Strangfeld A, et al. Ann Rheum Dis. 2021; 80(7):930-42.

[2]Kroon FPB, et al. Ann Rheum Dis. 2021.

[3]Ostrov BE, et al. Immunol Invest. 2021;50(7):833-56.

[4]Trinité B, et al. Sci Rep. 2021;11(1):2608.

Disclosure of Interests

None declared

Sustained low disease activity measured by ASDAS slow radiographic spinal progression in axial spondyloarthritis patients treated with TNF-inhibitors: data from REGISPONSERBIO

Background

To evaluate the influence of the disease activity on radiographic progression in axial spondyloarthritis (axSpA) patients treated with TNF inhibitors (TNFi).

Methods

The study included 101 axSpA patients from the Spanish Register of Biological Therapy in Spondyloarthritides (REGISPONSERBIO), which had clinical data and radiographic assessment available. Patients were classified into 2 groups based on the duration of TNFi treatment at baseline: (i) long-term treatment (≥4 years) and (ii) no long-term treatment (< 4 years). Radiographs were scored by two readers according to the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) with known chronology. Disease activity differences between patients’ groups at each time point were assessed using a linear mixed-effect model.

Results

Radiographic progression was defined as an increase in ≥2 mSASSS units. At inclusion, approximately half of the patients (45.5%) were receiving long-term treatment with TNFi (≥4 years). In this group of subjects, a significant difference in averaged Ankylosing Spondylitis disease Activity Score (ASDAS) across follow-up was found between progressors and non-progressors (2.33 vs 1.76, p=0.027, respectively). In patients not under long-term TNFi treatment (54.5%) though, no significant ASDAS differences were observed between progressors and non-progressors until the third year of follow-up. Furthermore, no significant differences were found in progression status, when disease activity was measured by Bath Ankylosing spondylitis Disease Activity Index (BASDAI) and C reactive protein (CRP).

Conclusions

Patients on long-term TNFi treatment with a mean sustained low disease activity measures by ASDAS presented lower radiographic progression than those with active disease.

Synovial Adiponectin Was More Associated with Clinical Severity than Synovial Leptin in Women with Knee Osteoarthritis

OBJECTIVE

Different adipokines have been reported to play a role in the development, progression, and severity of knee osteoarthritis, but this association may be mediated by obesity. The aim of this study was to evaluate separately the associations of leptin and adiponectin with clinical severity and inflammatory markers in nonobese and obese women with knee osteoarthritis.

DESIGN

Cross-sectional study with systematic inclusion of 115 women with symptomatic primary knee osteoarthritis. Age, physical exercise, symptoms duration, and body mass index were collected. Radiographic severity was evaluated according to Kellgren-Lawrence scale. Pain and disability were assessed by WOMAC-total, -pain, -function subscales. Two adipokines (leptin and adiponectin) and 3 inflammatory markers (TNF-α, hsCRP, and IL-6) were measured by ELISA in synovial fluid and serum.

RESULTS

Synovial fluid adiponectin was associated with WOMAC pain, function, and total and with synovial fluid IL-6 in nonobese female knee osteoarthritis after controlling by confounders (partial correlation coefficient [PCC] = 0.395, 0.387, 0.427, and 0.649, respectively). Synovial fluid and serum leptin were significantly associated with IL-6 (PCC = 0.354) after controlling by confounders but associations with clinical severity and the rest of inflammatory markers were mitigated after control.

CONCLUSIONS

Adiponectin in synovial fluid was associated with clinical severity and local inflammatory markers in knee osteoarthritis women, while leptin relation was attenuated when controlled by confounders.

Bioactivity descriptors for uncharacterized chemical compounds

Chemical descriptors encode the physicochemical and structural properties of small molecules, and they are at the core of chemoinformatics. The broad release of bioactivity data has prompted enriched representations of compounds, reaching beyond chemical structures and capturing their known biological properties. Unfortunately, bioactivity descriptors are not available for most small molecules, which limits their applicability to a few thousand well characterized compounds. Here we present a collection of deep neural networks able to infer bioactivity signatures for any compound of interest, even when little or no experimental information is available for them. Our signaturizers relate to bioactivities of 25 different types (including target profiles, cellular response and clinical outcomes) and can be used as drop-in replacements for chemical descriptors in day-to-day chemoinformatics tasks. Indeed, we illustrate how inferred bioactivity signatures are useful to navigate the chemical space in a biologically relevant manner, unveiling higher-order organization in natural product collections, and to enrich mostly uncharacterized chemical libraries for activity against the drug-orphan target Snail1. Moreover, we implement a battery of signature-activity relationship (SigAR) models and show a substantial improvement in performance, with respect to chemistry-based classifiers, across a series of biophysics and physiology activity prediction benchmarks.

The epigenetic regulator Mll1 is required for Wnt-driven intestinal tumorigenesis and cancer stemness

Wnt/β-catenin signaling is crucial for intestinal carcinogenesis and the maintenance of intestinal cancer stem cells. Here we identify the histone methyltransferase Mll1 as a regulator of Wnt-driven intestinal cancer. Mll1 is highly expressed in Lgr5⁺ stem cells and human colon carcinomas with increased nuclear β-catenin. High levels of MLL1 are associated with poor survival of colon cancer patients. The genetic ablation of Mll1 in mice prevents Wnt/β-catenin-driven adenoma formation from Lgr5⁺ intestinal stem cells. Ablation of Mll1 decreases the self-renewal of human colon cancer spheres and halts tumor growth of xenografts. Mll1 controls the expression of stem cell genes including the Wnt/β-catenin target gene Lgr5. Upon the loss of Mll1, histone methylation at the stem cell promoters switches from activating H3K4 tri-methylation to repressive H3K27 tri-methylation, indicating that Mll1 sustains stem cell gene expression by antagonizing gene silencing through polycomb repressive complex 2 (PRC2)-mediated H3K27 tri-methylation. Transcriptome profiling of Wnt-mutated intestinal tumor-initiating cells reveals that Mll1 regulates Gata4/6 transcription factors, known to sustain cancer stemness and to control goblet cell differentiation. Our results demonstrate that Mll1 is an essential epigenetic regulator of Wnt/β-catenin-induced intestinal tumorigenesis and cancer stemness.

Intestinal cancer stem cells (CSC) are associated with colon cancer. Here, the authors show that Wnt/beta-catenin signalling in CSC requires the epigenetic regulator Mll1 to promote stemness and tumourigenesis in murine and human colon cancer models.

CD4 and CD8 Lymphocyte Counts as Surrogate Early Markers for Progression in SARS-CoV-2 Pneumonia: A Prospective Study

BACKGROUND

COVID-19 pathophysiology and the predictive factors involved are not fully understood, but lymphocytes dysregulation appears to play a role. This paper aims to evaluate lymphocyte subsets in the pathophysiology of COVID-19 and as predictive factors for severe disease.

PATIENT AND METHODS

A prospective cohort study of patients with SARS-CoV-2 bilateral pneumonia recruited at hospital admission. Demographics, medical history, and data regarding SARS-CoV-2 infection were recorded. Patients systematically underwent complete laboratory tests, including parameters related to COVID-19 as well as lymphocyte subsets study at the time of admission. Severe disease criteria were established at admission, and patients were classified on remote follow-up according to disease evolution. Linear regression models were used to assess associations with disease evolution, and Receiver Operating Characteristic (ROC) and the corresponding Area Under the Curve (AUC) were used to evaluate predictive values.

RESULTS

Patients with critical COVID-19 showed a decrease in CD3+CD4+ T cells count compared to non-critical (278 (485 IQR) vs. 545 (322 IQR)), a decrease in median CD4+/CD8+ ratio (1.7, (1.7 IQR) vs. 3.1 (2.4 IQR)), and a decrease in median CD4+MFI (21,820 (4491 IQR) vs. 26,259 (3256 IQR)), which persisted after adjustment. CD3+CD8+ T cells count had a high correlation with time to hospital discharge (PC = -0.700 (-0.931, -0.066)). ROC curves for predictive value showed lymphocyte subsets achieving the best performances, specifically CD3+CD4+ T cells (AUC = 0.756), CD4+/CD8+ ratio (AUC = 0.767), and CD4+MFI (AUC = 0.848).

CONCLUSIONS

A predictive value and treatment considerations for lymphocyte subsets are suggested, especially for CD3CD4+ T cells. Lymphocyte subsets determination at hospital admission is recommended.

ERK1/2 Signaling Induces Upregulation of ANGPT2 and CXCR4 to Mediate Liver Metastasis in Colon Cancer

Carcinoma development in colorectal cancer is driven by genetic alterations in numerous signaling pathways. Alterations in the RAS-ERK1/2 pathway are associated with the shortest overall survival for patients after diagnosis of colorectal cancer metastatic disease, yet how RAS-ERK signaling regulates colorectal cancer metastasis remains unknown. In this study, we used an unbiased screening approach based on selection of highly liver metastatic colorectal cancer cells in vivo to determine genes associated with metastasis. From this, an ERK1/2-controlled metastatic gene set (EMGS) was defined. EMGS was associated with increased recurrence and reduced survival in patients with colorectal cancer tumors. Higher levels of EMGS expression were detected in the colorectal cancer subsets consensus molecular subtype (CMS)1 and CMS4. ANGPT2 and CXCR4, two genes within the EMGS, were subjected to gain-of-function and loss-of-function studies in several colorectal cancer cell lines and then tested in clinical samples. The RAS-ERK1/2 axis controlled expression of the cytokine ANGPT2 and the cytokine receptor CXCR4 in colorectal cancer cells, which facilitated development of liver but not lung metastases, suggesting that ANGPT2 and CXCR4 are important for metastatic outgrowth in the liver. CXCR4 controlled the expression of cytokines IL10 and CXCL1, providing evidence for a causal role of IL10 in supporting liver colonization. In summary, these studies demonstrate that amplification of ERK1/2 signaling in KRAS-mutated colorectal cancer cells affects the cytokine milieu of the tumors, possibly affecting tumor-stroma interactions and favoring liver metastasis formation. SIGNIFICANCE: These findings identify amplified ERK1/2 signaling in KRAS-mutated colorectal cancer cells as a driver of tumor-stroma interactions that favor formation of metastases in the liver.

Regulation of tumor angiogenesis and mesenchymal-endothelial transition by p38α through TGF-β and JNK signaling

The formation of new blood vessels is essential for normal development, tissue repair and tumor growth. Here we show that inhibition of the kinase p38α enhances angiogenesis in human and mouse colon tumors. Mesenchymal cells can contribute to tumor angiogenesis by regulating proliferation and migration of endothelial cells. We show that p38α negatively regulates an angiogenic program in mesenchymal stem/stromal cells (MSCs), multipotent progenitors found in perivascular locations. This program includes the acquisition of an endothelial phenotype by MSCs mediated by both TGF-β and JNK, and negatively regulated by p38α. Abrogation of p38α in mesenchymal cells increases tumorigenesis, which correlates with enhanced angiogenesis. Using genetic models, we show that p38α regulates the acquisition of an endothelial-like phenotype by mesenchymal cells in colon tumors and damage tissue. Taken together, our results indicate that p38α in mesenchymal cells restrains a TGF-β-induced angiogenesis program including their ability to transdifferentiate into endothelial cells.

Mesenchymal cells contribute to tumor angiogenesis by regulating proliferation and migration of endothelial cells. Here, the authors show that mesenchymal stem cells also have the ability to acquire an endothelial phenotype upon TGF-β stimulation via the downstream kinase JNK, and that p38α negatively regulates this process.

Synovial fluid adipokines are associated with clinical severity in knee osteoarthritis: a cross-sectional study in female patients with joint effusion

Background

Adipokines are related to knee osteoarthritis, but their exact role is not well known. The aim of this study was to evaluate the association between adipokines in synovial fluid and clinical severity in patients with knee osteoarthritis with joint effusion.

Methods

Cross-sectional study with systematic inclusion of female patients with symptomatic primary knee osteoarthritis with ultrasound-confirmed joint effusion. Age, physical exercise, knee osteoarthritis symptoms duration, classical cardiovascular risk factors and different anthropometric measurements were collected. Metabolic syndrome was defined in accordance to National Cholesterol Education Program-Adult Treatment Panel III. Radiographic severity was evaluated according to Kellgren-Lawrence scale and Lequesne index was used to assess clinical severity. Seven adipokines (leptin, adiponectin, resistin, visfatin, osteopontin, omentin and chemerin) and three inflammatory markers (tumor necrosis factor α, interleukin 6 and high sensitivity C-reactive protein) were measured by enzyme-linked immunosorbent assay in synovial fluid.

Results

Kellgren-Lawrence grade, physical exercise, all anthropometric measurements (especially waist circumference), tumor necrosis factor α, and high levels of leptin, resistin, and ostepontin were related to knee osteoarthritis severity. After adjustment for clinical confounders (age, symptom duration, and radiology), anthropometric measurements, inflammatory markers, and all evaluated adipokines, there were independent associations with clinical severity for resistin (directly associated) and visfatin (inversely associated). No other adipokines or inflammatory markers were independently associated with Lequesne index. The association of radiological parameters, physical exercise, and waist circumference with Lequesne index remained after adjustment.

Conclusions

Resistin was directly associated, and visfatin was inversely associated, with clinical severity in female patients with knee osteoarthritis with joint effusion. These associations were more important after adjustment for confounders, especially when all adipokines were evaluated.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-016-1103-1) contains supplementary material, which is available to authorized users.

Mfn2 deficiency links age-related sarcopenia and impaired autophagy to activation of an adaptive mitophagy pathway

Mitochondrial dysfunction and accumulation of damaged mitochondria are considered major contributors to aging. However, the molecular mechanisms responsible for these mitochondrial alterations remain unknown. Here, we demonstrate that mitofusin 2 (Mfn2) plays a key role in the control of muscle mitochondrial damage. We show that aging is characterized by a progressive reduction in Mfn2 in mouse skeletal muscle and that skeletal muscle Mfn2 ablation in mice generates a gene signature linked to aging. Furthermore, analysis of muscle Mfn2-deficient mice revealed that aging-induced Mfn2 decrease underlies the age-related alterations in metabolic homeostasis and sarcopenia. Mfn2 deficiency reduced autophagy and impaired mitochondrial quality, which contributed to an exacerbated age-related mitochondrial dysfunction. Interestingly, aging-induced Mfn2 deficiency triggers a ROS-dependent adaptive signaling pathway through induction of HIF1α transcription factor and BNIP3. This pathway compensates for the loss of mitochondrial autophagy and minimizes mitochondrial damage. Our findings reveal that Mfn2 repression in muscle during aging is a determinant for the inhibition of mitophagy and accumulation of damaged mitochondria and triggers the induction of a mitochondrial quality control pathway.

Discovery and functional assessment of gene variants in the vascular endothelial growth factor pathway

Angiogenesis is a host-mediated mechanism in disease pathophysiology. The vascular endothelial growth factor (VEGF) pathway is a major determinant of angiogenesis, and a comprehensive annotation of the functional variation in this pathway is essential to understand the genetic basis of angiogenesis-related diseases. We assessed the allelic heterogeneity of gene expression, population specificity of cis expression quantitative trait loci (eQTLs), and eQTL function in luciferase assays in CEU and Yoruba people of Ibadan, Nigeria (YRI) HapMap lymphoblastoid cell lines in 23 resequenced genes. Among 356 cis-eQTLs, 155 and 174 were unique to CEU and YRI, respectively, and 27 were shared between CEU and YRI. Two cis-eQTLs provided mechanistic evidence for two genome-wide association study findings. Five eQTLs were tested for function in luciferase assays and the effect of two KRAS variants was concordant with the eQTL effect. Two eQTLs found in each of PRKCE, PIK3C2A, and MAP2K6 could predict 44%, 37%, and 45% of the variance in gene expression, respectively. This is the first analysis focusing on the pattern of functional genetic variation of the VEGF pathway genes in CEU and YRI populations and providing mechanistic evidence for genetic association studies of diseases for which angiogenesis plays a pathophysiologic role.

Expression and methylation profiles associated with recurrent mutations in stage II colorectal cancer

e14613

Background: Aberration of normal genetic and epigenetic patterns occurs at early stages of colorectal cancer (CRC) and accumulates throughout cancer progression. To characterize pre-metastatic tumors, a series of stage II, microsatellite stable, colon tumors and their paired mucosa were profiled on RNA expression and DNA methylation microarrays ( www.colonomics.org ). Our aim is to define molecular subtypes based on recurrent gene mutations, methylation and expression profiles, and explore if these molecular subtypes are associated to patients’ prognosis. Methods: We have sequenced exomes (Illumina Genome Analyzer) of a subset of 42 COLONOMICS normal-tumor paired samples (21 good and 21 bad prognosis). Variants identified in normal tissue were used to filter SNPs. DNA methylation (Infinium Human Methylation 450k) and RNA expression (Affymetrix U219) data from those samples were used in this analysis. Correlation was used to assess the association between tumor mutations and differentially expressed/methylated genes. Significant genes were subsequently used to perform tumor clustering. Results: Exome analysis revealed a mean of 150 somatic mutations per sample. From these, 12 variants were recurrently mutated (KRAS, TP53, etc) in more than 3 tumors that were used to define tumor subtypes based on gene methylation/expression patterns. We obtained 12 profiles that clearly identified the cluster of mutated samples. For some profiles, the cluster only includes those tumors with the mutation. Interestingly, some clusters included the mutated samples and additional tumors showing the same phenotype despite not having the mutation. For each mutation, the overlapping between the differently methylated/expressed genes ranged from 14 to 200 common genes. When combining data from the three platforms two main CRC molecular subtypes emerge; each of which shows molecular heterogeneity but no association with prognosis. Conclusions: Mutational status is associated with gene methylation and expression patterns in CRC patients. Although none of these clusters was associated with prognosis, different groups of tumors could be related to distinctive pathways, which may reveal useful as therapeutic targets.