Bias in effect size of systemic lupus erythematosus susceptibility loci across Europe: a case-control study

Introduction

Prevalence of an abnormal Papanicolaou smear was significantly increased in lupus patients in cross-sectional studies, associated with a higher prevalence of high-risk human papillomavirus (HPV) infection. The nucleic acid-specific Toll-like receptors (TLRs) locate at the endolysosomal compartments and trigger the induction of cytokines for the innate immune response. This study evaluated whether abnormal host innate immune response in lupus patients may enhance HPV persistence.

Methods

Protein levels of TLRs 3, 7, 8 and 9 in cervical epithelial cells of lupus patients and controls with or without HPV infection were assessed using flow cytometry. Characteristics associated with the differential expression of TLRs in systemic lupus erythematosus (SLE) were elucidated. The effect and interferon-stimulated genes (ISGs) (ISG15 and Mx-1) gene expressions were then measured in oncogenic HeLa (HPV18), CaSki (HPV) and C33A (HPV negative) cell lines using flow cytometry and quantitative real-time PCR. Ex vivo productions of cytokines and interferon-gamma (IFN-??) upon TLR ligands stimulations were subsequently measured using cytometric bead array and ELISA.

Results

For subjects with HPV infection, levels of TLR3 and TLR7 were significantly lower in lupus patients compared with controls. Significantly decreased TLRs 7, 8 and 9 levels were observed in HPV-negative SLE compared to healthy controls. For SLE with and without HPV infection, TLR7 and 9 levels were significantly lower in infected SLE than those in HPV-negative patients. Independent explanatory variables associated with down-regulation of TLR7 level included HPV infection and a higher cumulative dose of prednisolone; while a higher cumulative dose of hydroxychloroquine and HPV infection were associated with down-regulation of TLR9 level. In cervical cell lines, TLRs 3, 7, 8, 9 protein levels and antiviral ISG15 and Mx-1 gene expressions were inhibited in two oncogenic HPV types. Functional data showed that the induction of pro-inflammatory cytokines by TLR ligands (R837, ssRNA and ODN2395) was greatly impaired in CaSki and HeLa than C33A cells.

Conclusions

In conclusion, prednisolone and TLR antagonist (hydroxychloroquine) may down-regulate protein levels of TLR7 and TLR9 in lupus patients, thereby decreasing the innate immune response against HPV infection. Upon infection, HPV further down-regulate TLR7 and 9 levels for viral persistence. Furthermore, reduction of nucleic acid-sensing TLRs 7, 8 and 9 in carcinogenic HPVs ensures that the expression of inducible pro-inflammatory cytokines is minimized to prevent the expression of antiviral ISGs (ISG15 and Mx-1) on a biologically relevant antiviral response.     

Bias in effect size of systemic lupus erythematosus susceptibility loci across Europe: a case-control study

Introduction

We aimed to investigate whether the effect size of the systemic lupus erythematosus (SLE) risk alleles varies across European subpopulations.

Methods

European SLE patients (n = 1,742) and ethnically matched healthy controls (n = 2,101) were recruited at 17 centres from 10 different countries. Only individuals with self-reported ancestry from the country of origin were included. In addition, participants were genotyped for top ancestry informative markers and for 25 SLE associated SNPs. The results were used to compare effect sizes between the Central Eureopan and Southern European subgroups.

Results

Twenty of the 25 SNPs showed independent association with SLE, These SNPs showed a significant bias to larger effect sizes in the Southern subgroup, with 15/20 showing this trend (P = 0.019) and a larger mean odds ratio of the 20 SNPs (1.46 vs. 1.34, P = 0.02) as well as a larger difference in the number of risk alleles (2.06 vs. 1.63, P = 0.027) between SLE patients and controls than for Central Europeans. This bias was reflected in a very significant difference in the cumulative genetic risk score (4.31 vs. 3.48, P = 1.8 × 10^-32). Effect size bias was accompanied by a lower number of SLE risk alleles in the Southern subjects, both patients and controls, the difference being more marked between the controls (P = 1.1 × 10^-8) than between the Southern and Central European patients (P = 0.016). Seven of these SNPs showed significant allele frequency clines.

Conclusion

Our findings showed a bias to larger effect sizes of SLE loci in the Southern Europeans relative to the Central Europeans together with clines of SLE risk allele frequencies. These results indicate the need to study risk allele clines and the implications of the polygenic model of inheritance in SLE.     

Circadian timing of injury-induced cell proliferation in zebrafish

In certain vertebrates such as the zebrafish, most tissues and organs including the heart and central nervous system possess the remarkable ability to regenerate following severe injury. Both spatial and temporal control of cell proliferation and differentiation is essential for the successful repair and re-growth of damaged tissues. Here, using the regenerating adult zebrafish caudal fin as a model, we have demonstrated an involvement of the circadian clock in timing cell proliferation following injury. Using a BrdU incorporation assay with a short labeling period, we reveal high amplitude daily rhythms in S-phase in the epidermal cell layer of the fin under normal conditions. Peak numbers of S-phase cells occur at the end of the light period while lowest levels are observed at the end of the dark period. Remarkably, immediately following amputation the basal level of epidermal cell proliferation increases significantly with kinetics, depending upon the time of day when the amputation is performed. In sharp contrast, we failed to detect circadian rhythms of S-phase in the highly proliferative mesenchymal cells of the blastema. Subsequently, during the entire period of outgrowth of the new fin, elevated, cycling levels of epidermal cell proliferation persist. Thus, our results point to a preferential role for the circadian clock in the timing of epidermal cell proliferation in response to injury.     

A two-stage sequential planning scheme for integrated operations planning and scheduling system using MILP: the case of an engine assembler

This paper presents an operations planning scheme based on mathematical programming models (specifically, Mixed-Integer Linear Programming (MILP) models) integrated into a web-enabled Advanced Planning and Scheduling System (APS), developed for and implemented in an engine assembler that supplies the car industry. One objective of this paper is to provide empirical insights into some operations planning characteristics in the automotive industry. The other main objective is to show MILP models and their use to create plans that enable the coordination of different planning levels (mid-term and short-term) and planning domains (procurement, production and distribution). The APS fulfills the requirements of an engine assembler in the automotive sector (namely lean-type constraints and objectives). The system is based on two MILP models, which have been purposely developed together along with their relations. The models presented herein provide a solution that considers supply chain objectives and constraints, and are integrated by means of data and constraints which have proven sufficient to fulfill users?? and stakeholders?? requirements. This case study presents the models?? most relevant aspects and their implementation.     

Whole-body vibration increases upper and lower body muscle activity in older adults: potential use of vibration accessories

The current study examined the effects of whole-body vibration (WBV) on upper and lower body muscle activity during static muscle contractions (squat and bicep curls). The use of WBV accessories such as hand straps attached to the platform and a soft surface mat were also evaluated. Surface electromyography (sEMG) was measured for the medial gastrocnemius (MG), vastus lateralis (VL), and biceps brachii (BB) muscles in fourteen healthy older adults (74.8±4.5 years; mean±SD) with a WBV stimulus at an acceleration of 40 m s(-2) (30 Hz High, 2.5 mm or 46 Hz Low, 1.1 mm). WBV increased lower body (VL and MG) sEMG vs baseline (no WBV) though this was decreased with the use of the soft mat. The addition of the bicep curl with hand straps had no effect on lower body sEMG. WBV also increased BB sEMG vs baseline which was further increased when using the hand straps. There was no upper body effect of the soft mat. This study demonstrates WBV increases both lower and upper body muscle activity in healthy older adults. Moreover, WBV accessories such as hand straps attached to the platform or a soft surface mat may be used to alter exercise intensity.     

Three weeks of erythropoietin treatment hampers skeletal muscle mitochondrial biogenesis in rats

The blood O₂-carrying capacity is maintained by the O₂-regulated production of erythropoietin (Epo), which stimulates the proliferation and survival of red blood cell progenitors. Epo has been thought to act exclusively on erythroid progenitor cells. However, recent studies have identified the erythropoietin receptor (EpoR) in other cells, such as neurons, astrocytes, microglia, heart, cancer cell lines, and skeletal muscle provides evidence for a potential role of Epo in other tissues. In this study we aimed to determine the effect of recombinant human erythropoietin (rHuEpo) on skeletal muscle adaptations such as mitochondrial biogenesis, myogenesis, and angiogenesis in different muscle fibre types. Fourteen male Wistar rats were randomly divided into two experimental groups, and saline or rHuEpo (300?IU) was administered subcutaneously three times a week for 3?weeks. We evaluated the protein expression of intermediates involved in the mitochondrial biogenesis cascade, the myogenic cascade, and in angiogenesis in the oxidative soleus muscle and in the glycolytic gastrocnemius muscle. Contrary to our expectations, rHuEpo significantly hampered the mitochondrial biogenesis pathway in gastrocnemius muscle (PGC-1??, mTFA and cytochrome c). We did not find any effect of the treatment on cellular signals of myogenesis (MyoD and Myf5) or angiogenesis (VEGF) in either soleus or gastrocnemius muscles. Finally, we found no significant effect on the maximal aerobic velocity at the end of the experiment in the rHuEpo-treated animals. Our findings suggest that 3?weeks of rHuEpo treatment, which generates an increase of oxygen carrying capacity, can affect mitochondrial biogenesis in a muscle fibre-specific dependent manner.