Shift work at young age is associated with increased risk of multiple sclerosis in a Danish population.

BACKGROUND: Epidemiological studies suggest an important role for environmental factors in developing multiple sclerosis (MS). Furthermore several studies have indicated that the effect of environmental factors may be especially pronounced in adolescents. Recently only one study investigated and found that shift work at young age is associated with an increased risk of developing MS. In this study we focused on the effect of shift work in the vulnerable period between 15-19 years. OBJECTIVE: The aim of this study was to investigate the association between shift work at young age and the risk of developing MS. METHODS: We performed a large case-control study including 1723 patients diagnosed with MS and 4067 controls. MS patients were recruited from the Danish Multiple Sclerosis Biobank and controls from The Danish Blood Donor Study. Information on working patterns and lifestyle factors was obtained using a comprehensive lifestyle-environmental factor questionnaire with participants enrolled between 2009 and 2014. Logistic regression models were used to investigate the association between shift work at age 15-19 years and the subsequent risk of MS and were controlled for effects due to established MS risk factors. RESULTS: We found a statistically significant association when total numbers of night shifts were compared with non-shift workers. For every additional 100 night shifts the odds ratio (OR) for MS was 1.20 (95% confidence interval (CI), 1.08-1.34, p=0.001). Increasing intensity of shift work also increased MS risk. For every additional night per month the OR was 1.04 (95% CI, 1.01-1.06, p=0.002). Duration of shift work in years was not associated with risk of MS. CONCLUSION: This study supports a statistically significant association between shift work at age 15-19 years and MS risk.

Identification of Suitable Reference Genes for Peripheral Blood Mononuclear Cell Subset Studies in Multiple Sclerosis.

Quantitative real-time PCR (qPCR) involves the need of a proper standard for normalizing the gene expression data. Different studies have shown the validity of reference genes to vary greatly depending on tissue, cell subsets and experimental context. This study aimed at the identification of suitable reference genes for qPCR studies using different peripheral blood cell subsets (whole blood (WB) cells, peripheral blood mononuclear cells (PBMCs) and PBMC subsets (CD4(+) T cells, CD8(+) T cells, NK cells, monocytes, B cells and dendritic cells) from healthy controls (HC), patients with relapsing-remitting multiple sclerosis (RRMS) and interferon-ß-treated patients with RRMS (RRMS-IFN-ß). Eight candidate reference genes (CASC3, EEF1A1, GAPDH, HPRT1, RPLP0, UBC, UBE2D2 and YWHAZ) were analysed using normfinder and genorm algorithms to identify the most stably expressed genes. We found reference gene expression varied most across cell subsets, and less variation between the donor groups. UBE2D2 was the most stably expressed gene across both HC and RRMS patients and across cell subsets, while UBC was the most stably expressed gene between HC, RRMS and RRMS-IFN-ß patients. UBE2D2 and HPRT1 was the most stable combination for analyses of cell subsets between HC and RRMS patients, while the combination of UBC and YWHAZ was superior for analysis of cell subsets between HC, RRMS and RRMS-IFN-ß groups. GAPDH was generally unsuitable for blood cell subset studies in multiple sclerosis. In conclusion, we found that blood cell subsets result in marked variation in reference gene expression, and we identified suitable reference genes for studies involving PBMC subsets, RRMS patients and interferon-ß treatment.

Short-term, high-dose glucocorticoid treatment does not contribute to reduced bone mineral density in patients with multiple sclerosis.

BACKGROUND: Patients with multiple sclerosis (MS) are at increased risk of reduced bone mineral density (BMD). A contributing factor might be treatment with high-dose glucocorticoids (GCs). OBJECTIVES: The objective of this paper is to assess bone mass in patients with MS and evaluate the importance of short-term, high-dose GC treatment and other risk factors that affect BMD in patients with MS. METHODS: A total of 260 patients with MS received short-term high-dose GC treatment and had their BMD measured by dual x-ray absorptiometry. BMD was compared to a healthy age-matched reference population (Z-scores). Data regarding GCs, age, body mass index (BMI), serum 25(OH)D, disease duration and severity were collected retrospectively and analysed in a multiple linear regression analysis to evaluate the association between each risk factor and BMD. RESULTS: Osteopenia was present in 38% and osteoporosis in 7% of the study population. Mean Z-score was significantly below zero, indicating a decreased BMD in our MS patients. Multiple linear regression analysis showed no significant association between GCs and BMD. In contrast, age, BMI and disease severity were independently associated with both lumbar and femoral BMD. CONCLUSION: Reduced BMD was prevalent in patients with MS. GC treatment appears not to be the primary underlying cause of secondary osteoporosis in MS patients.