Dysregulated energy metabolism impairs chondrocyte function in osteoarthritis

OBJECTIVES

Metabolic pathways are a series of chemical reactions by which cells take in nutrient substrates for energy and building blocks needed to maintain critical cellular processes. Details of chondrocyte metabolism and how it rewires during the progression of osteoarthritis (OA) are unknown. This research aims to identify what changes in the energy metabolic state occur in OA cartilage.

METHODS

Patient matched OA and non-OA cartilage specimens were harvested from total knee replacement patients. Cartilage was first collected for metabolomics, proteomics, and transcriptomics analyses to study global alterations in OA metabolism. We then determined the metabolic routes by tracking [U-¹³C] isotope with liquid chromatography-mass spectrometry (LC-MS). We further evaluated cellular bioenergetic profiles by measuring oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) and investigated the effects of low-dose and short-term effects of 2-deoxyglucose (2DG) on chondrocytes.

RESULTS

OA chondrocytes showed increased basal ECAR and more lactate production compared to non-OA chondrocytes. [U-¹³C] glucose labelling revealed that less glucose-derived carbon entered the tricarboxylic acid (TCA) cycle. On the other hand, mitochondrial respiratory rates were markedly decreased in the OA chondrocytes compared to non-OA chondrocytes. These changes were accompanied by decreased cellular ATP production, mitochondrial membrane potential and disrupted mitochondrial morphology. We further demonstrated in vitro that short-term inhibition of glycolysis suppressed matrix degeneration gene expression in chondrocytes and bovine cartilage explants cultured under inflammatory conditions.

CONCLUSION

This study represents the first comprehensive comparative analysis of metabolism in OA chondrocytes and lays the groundwork for therapeutic targeting of metabolism in OA.

Sex related differences in exercise performance in patients with hypertrophic cardiomyopathy: hemodynamic insights through non-invasive pressure volume analysis

Background

Women with HCM have worse cardiopulmonary exercise performance compared to men. We used non-invasive pressure-volume (PV) analysis to delineate sex related hemodynamic differences in HCM.

Methods

PV loops were constructed from echocardiograms using left ventricular (LV) volumes indexed to body surface area, Doppler estimates of LV end-diastolic pressure and blood pressure. The end-systolic PV relationship (ESPVR) and end-diastolic PV relationship (EDPVR) were derived from validated single-beat techniques. The area between the ESPVR and EDPVR (isovolumetric PV area), was indexed to an LV end-diastolic pressure of 30mmHg (PVAiso30), as the integrated metric of LV function. LV volume at an end-diastolic pressure of 30mmHg (V30) indexed ventricular capacity.

Results

202 patients were included, 56 women. Women were older (51 vs 44 yrs, p=0.012) and had reduced exercise capacity (5.6 vs 6.9 METs, p<0.001). Only 32 patients (16%) had a peak gradient >30mmHg at rest with no sex differences. Women had significantly lower indexed PVAiso30 (6577 vs 7767 mmHg·mL/m2, p<0.001) driven by reduced ventricular capacitance (V30 54 vs 62 ml/m2, p<0.001). In multivariable linear regression indexed V30 was an independent predictor of exercise capacity.

Conclusion

Impaired exercise capacity in women with HCM appears strongly related to abnormalities in passive diastolic properties, suggesting a unique pathophysiology compared to men, and a potential difference in viable therapeutic molecular targets

Funding Acknowledgement

Type of funding sources: None.

MSR1 repeats modulate gene expression and affect risk of breast and prostate cancer

Background

MSR1 repeats are a 36-38 bp minisatellite element that have recently been implicated in the regulation of gene expression, through copy number variation (CNV).

Patients and methods

Bioinformatic and experimental methods were used to assess the distribution of MSR1 across the genome, evaluate the regulatory potential of such elements and explore the role of MSR1 elements in cancer, particularly non-familial breast cancer and prostate cancer.

Results

MSR1s are predominately located at chromosome 19 and are functionally enriched in regulatory regions of the genome, particularly regions implicated in short-range regulatory activities (H3K27ac, H3K4me1 and H3K4me3). MSR1-regulated genes were found to have specific molecular roles, such as serine-protease activity (P = 4.80 × 10-7) and ion channel activity (P = 2.7 × 10-4). The kallikrein locus was found to contain a large number of MSR1 clusters, and at least six of these showed CNV. An MSR1 cluster was identified within KLK14, with 9 and 11 copies being normal variants. A significant association with the 9-copy allele and non-familial breast cancer was found in two independent populations (P = 0.004; P = 0.03). In the white British population, the minor allele conferred an increased risk of 1.21-3.51 times for all non-familial disease, or 1.7-5.3 times in early-onset disease. The 9-copy allele was also found to be associated with increased risk of prostate cancer in an independent population (odds ratio = 1.27-1.56; P =0.009).

Conclusions

MSR1 repeats act as molecular switches that modulate gene expression. It is likely that CNV of MSR1 will affect risk of development of various forms of cancer, including that of breast and prostate. The MSR1 cluster at KLK14 represents the strongest risk factor identified to date in non-familial breast cancer and a significant risk factor for prostate cancer. Analysis of MSR1 genotype will allow development of precise stratification of disease risk and provide a novel target for therapeutic agents.

Identification of a novel prostate cancer susceptibility variant in the KLK3 gene transcript

Genome-wide association studies (GWAS) have identified more than 30 prostate cancer (PrCa) susceptibility loci. One of these (rs2735839) is located close to a plausible candidate susceptibility gene, KLK3, which encodes prostate-specific antigen (PSA). PSA is widely used as a biomarker for PrCa detection and disease monitoring. To refine the association between PrCa and variants in this region, we used genotyping data from a two-stage GWAS using samples from the UK and Australia, and the Cancer Genetic Markers of Susceptibility (CGEMS) study. Genotypes were imputed for 197 and 312 single nucleotide polymorphisms (SNPs) from HapMap2 and the 1000 Genome Project, respectively. The most significant association with PrCa was with a previously unidentified SNP, rs17632542 (combined P = 3.9 × 10⁻²²). This association was confirmed by direct genotyping in three stages of the UK/Australian GWAS, involving 10,405 cases and 10,681 controls (combined P = 1.9 × 10⁻³⁴). rs17632542 is also shown to be associated with PSA levels and it is a non-synonymous coding SNP (Ile179Thr) in KLK3. Using molecular dynamic simulation, we showed evidence that this variant has the potential to introduce alterations in the protein or affect RNA splicing. We propose that rs17632542 may directly influence PrCa risk.

Interleukin-10 promoter polymorphisms and atopic asthma in North Indians

BACKGROUND

IL-10 is an anti-inflammatory cytokine primarily produced by monocytes and macrophages and plays a key role in asthma. IL10 gene, present in chromosome 1q31-q32, is regulated primarily by transcription and its expression is found to be lower in asthmatics. Earlier studies in diverse populations have identified several promoter polymorphisms. However, no study has been carried out in a genetically untapped large population from the Indian Subcontinent.

OBJECTIVE

To investigate the association of the IL10 promoter polymorphisms and asthma in the North Indian population.

METHODS

The association study was conducted in a case-control as well as in a family-based design. Polymorphism at -1082 A/G, -819 C/T and -592 C/A nucleotides were genotyped in ethnically matched unrelated patients (N=272), unrelated controls (N=307) and nuclear families (N=164).

RESULTS

A suggestive evidence of association was obtained for -1082 A/G polymorphism at the level of alleles and genotypes with asthma in the case-control study (P=0.03). A three-locus haplotype (ATA) was found to be more in asthmatics than in control individuals (P=0.0085). On the other hand, a novel haplotype ATC was found to be more in controls than in asthmatics (P=0.012). These results were further tested in a family-based study. A deviation of transmission was observed for the -1082 A/G polymorphism (P=0.003). The ATA haplotype showed a preferential transmission in asthmatics (P=0.03), while the GCC and a novel ATC haplotype showed preferential non-transmission in asthmatic individuals (P=0.03 and 0.001, respectively).

CONCLUSIONS

Using both case-control and family studies, we provide suggestive evidence that the ATA haplotype is positively, whereas GCC and a novel ATC haplotypes of IL10 gene are negatively associated with asthma in Indian population. Our results are interesting enough as to intensify further research to elucidate the functional significance of these single-nucleotide polymorphisms and haplotypes in asthma pathogenesis.

In vitro and in vivo activity of a recombinant toxin, OLX-209, which targets the erbB-2 oncoprotein

OLX-209 has readily measurable activity, is safe in experimental animals, and is efficacious in model systems. These results support the concept of OLX-209 and provide groundwork for further development of this oncoprotein targeted agent.