Michael G. Molloy

Germline Mutations in the Extracellular Domains of the 55 kDa TNF Receptor, TNFR1, Define a Family of Dominantly Inherited Autoinflammatory Syndromes

Autosomal dominant periodic fever syndromes are characterized by unexplained episodes of fever and severe localized inflammation. In seven affected families, we found six different missense mutations of the 55 kDa tumor necrosis factor receptor (TNFR1), five of which disrupt conserved extracellular disulfide bonds. Soluble plasma TNFR1 levels in patients were approximately half normal. Leukocytes bearing a C52F mutation showed increased membrane TNFR1 and reduced receptor cleavage following stimulation. We propose that the autoinflammatory phenotype results from impaired downregulation of membrane TNFR1 and diminished shedding of potentially antagonistic soluble receptor. TNFR1-associated periodic syndromes (TRAPS) establish an important class of mutations in TNF receptors. Detailed analysis of one such mutation suggests impaired cytokine receptor clearance as a novel mechanism of disease.

Exercise and associated dietary extremes impact on gut microbial diversity

Objective The commensal microbiota, host immunity and metabolism participate in a signalling network, with diet influencing each component of this triad. In addition to diet, many elements of a modern lifestyle influence the gut microbiota but the degree to which exercise affects this population is unclear. Therefore, we explored exercise and diet for their impact on the gut microbiota. Design Since extremes of exercise often accompany extremes of diet, we addressed the issue by studying professional athletes from an international rugby union squad. Two groups were included to control for physical size, age and gender. Compositional analysis of the microbiota was explored by 16S rRNA amplicon sequencing. Each participant completed a detailed food frequency questionnaire. Results As expected, athletes and controls differed significantly with respect to plasma creatine kinase (a marker of extreme exercise), and inflammatory and metabolic markers. More importantly, athletes had a higher diversity of gut micro-organisms, representing 22 distinct phyla, which in turn positively correlated with protein consumption and creatine kinase. Conclusions The results provide evidence for a beneficial impact of exercise on gut microbiota diversity but also indicate that the relationship is complex and is related to accompanying dietary extremes.

Hyponatremia independent of osteoporosis is associated with fracture occurrence.

BACKGROUND AND OBJECTIVES Mild hyponatremia has traditionally been considered benign, but it may be associated with gait and attention deficits and an increased risk of falls that may result in fracture. A retrospective study was conducted to quantify the association of hyponatremia with fracture occurrence and to examine whether this relationship is independent of osteoporosis. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS This study analyzed 1408 consecutive female patients who underwent bone mineral density measurement (Lunar IDXA) between September 1, 2006 and April 11, 2007 and who had available laboratory data. Self reported fracture occurrence was confirmed by radiology report or attendance at a fracture clinic. The significance and independence of the association of hyponatremia with fracture was quantified using logistic regression. RESULTS The mean (SD) serum sodium ([Na(+)]) was 140.6 (3.0) mmol/L; 59 (4.2%) had [Na(+)] < 135 mmol/L. Forty-five percent of subjects were osteoporotic and 18% had a prior fracture. Hyponatremia was present in 8.7% of those with versus 3.2% of those without a confirmed fracture (P < 0.001). On multivariate logistic regression analysis controlling for age, T-score, chronic kidney disease stage, osteoporotic risk factors (amenorrhea, family history, regular steroid use, smoking history, alcohol use, history of liver disease, and low-calcium diet), and osteoporosis treatments (calcium and vitamin D supplements, antiresorptives, and hormonal replacement therapy), [Na(+)] < 135 versus [Na(+)] >or= 135 mmol/L remained significantly and independently associated with fracture occurrence (P < 0.01). CONCLUSIONS Mild hyponatremia may be a readily identifiable and potentially modifiable risk factor for fracture.

International Rugby Board Rugby World Cup 2007 injury surveillance study

Objective: to determine the incidence, nature and causes of injuries sustained during the International Rugby Board (IRB) Rugby World Cup 2007. Design: Pospective, whole-population survey. Population: 626 international rugby players representing 20 teams competing at the IRB Rugby World Cup 2007 in France. Methods: The survey followed the international consensus procedures for studies of injuries in rugby union; the main outcome measures were incidence of match and training injuries (number of injuries/1000 player hours), severity (days absence), location, type and cause of injury. Results: the incidence of injuries was 83.9/1000 player-match hours (forwards 84.0; backs 83.7) and 3.5/1000 player-training hours (forwards 3.5; backs 3.6). The average severity of injuries was 14.7 days (forwards 14.0; backs 15.5) during matches and 17.8 (forwards 15.9; backs 19.8) during training. Lower limb muscle and ligament injuries were the main injuries during both matches and training. Most injuries were sustained in the tackle during matches and in full-contact skills activities during training. Conclusions: This study shows the application of the methodology described in the international consensus statement on injury surveillance studies in rugby union and provides benchmark values for the incidence, severity, nature and causes of match and training injuries sustained during the IRB Rugby World Cup.

Tumour necrosis factor 5' promoter single nucleotide polymorphisms influence susceptibility to rheumatoid arthritis (RA) in immunogenetically defined multiplex RA families.

Tumour necrosis factor (TNF) plays a pivotal role in the pathogenesis of rheumatoid arthritis (RA) and it has been shown that the TNF-lymphotoxin (TNF-LT) region influences susceptibility to RA. To investigate the role of the TNF-LT locus further, inheritance of TNF 5′ promoter alleles was determined in multiplex RA families. Six previously defined TNF promoter single nucleotide polymorphisms (SNPs) (−238, −308, −376, −857, −863, −1031) were observed in these families and in addition, a heretofore undocumented adenine (A) to cytosine (C) substitution at position −572 relative to the transcription start site was defined. TNF 5′ promoter SNPs were found to co-segregate with specific TNF microsatellite haplotypes. In particular, the SNP −308A allele was found to be inherited with the TNF a2, b3, c1, d1, e3 (H2) microsatellite haplotype (P < 0.001) which had previously been found to be associated with RA in individuals heterozygous for the HLA-DR ‘shared epitope’ (SE). When the data were stratified by the presence of the SE with further stratification according to SE DR subtypes and analysed by transmission disequilibrium test (TDT) for which offspring were assumed independent, the −308A and −857T alleles were found to be associated with RA in patients carrying the SE (P = 0.0076 and 0.0063 respectively). The data were further stratified to analyse for association in individuals homozygous or heterozygous for SE alleles. Results showed that the −308A allele was significantly associated with RA susceptibility in individuals heterozygous for the SE (P < 0.001) with the significance only occurring in patients carrying HLA-DR4 (P < 0.001), while the −857T allele was significant in individuals homozygous for the SE (P = 0.0039). Further analysis using the pedigree disequilibrium test (PDT) which conservatively adjusts for all sources of familial correlation except that conferred by linkage disequilibrium still indicated a significant role for the −308A and −857T alleles. These data provide evidence that TNF promoter SNPs may play an independent role in RA susceptibility in specific immunogenetically-defined groups of RA patients.

Linkage of familial Hibernian fever to chromosome 12p13.

Autosomal dominant periodic fevers are characterized by intermittent febrile attacks of unknown etiology and by recurrent abdominal pains. The biochemical and molecular bases of all autosomal dominant periodic fevers are unknown, and only familial Hibernian fever (FHF) has been described as a distinct clinical entity. FHF has been reported in three families-the original Irish-Scottish family and two Irish families with similar clinical features. We have undertaken a genomewide search in these families and report significant multipoint LOD scores between the disease and markers on chromosome 12p13. Cumulative multipoint linkage analyses indicate that an FHF gene is likely to be located in an 8-cM interval between D12S77 and D12S356, with a maximum LOD score (Z max) of 3.79. The two-point Z max was 3.11, for D12S77. There was no evidence of genetic heterogeneity in these three families; it is proposed that these markers should be tested in other families, of different background, that have autosomal dominant periodic fever, as a prelude to identification of the FHF-susceptibility gene.

Investigation of the Genetic Influence of the OPG, VDR (Fok1), and COLIA1 Sp1 Polymorphisms on BMD in the Irish Population

Low bone mineral density (BMD) is a major risk factor for the development of osteoporosis and there is strong evidence to suggest that the procurement and preservation of peak BMD is genetically determined. In an effort to identify factors responsible for susceptibility to low BMD in the Irish population, we investigated its possible association with polymorphisms in the Osteoprotegerin (OPG) gene, Type I collagen alpha 1 (COLIA1) Sp1 binding site and vitamin D receptor (VDR) start codon. Following a systematic screening of the regulatory and coding regions of the OPG gene, we identified a novel G1181C polymorphism in exon 1 and a T950C polymorphism in the promoter region of the OPG gene. Participants were recruited from the Bone Densitometry Unit of Cork University Hospital, including 381 postmenopausal women aged 61.26 +/- 8.50 (mean +/- SD) and 130 premenopausal women aged 46.30 +/- 6.50 (mean +/- SD). Following association analysis using both the premenopausal and postmenopausal cohorts we found that postmenopausal women carrying one or more C alleles of the G1181C polymorphism had 14.8% lower BMD (P = 0.05) at the lumbar spine and 14.4% lower BMD (P = 0.04) at the FN. However, both were nonsignificant when the Bonferroni correction factor (0.01 significance level) was applied to correct for multiple hypothesis testing. We found no association between alleles of the T950C OPG polymorphism and BMD. Similarly, we have found a lack of association between the VDR (fok1) polymorphism or COLIA1 Sp1 polymorphism and low BMD in either postmenopausal or premenopausal women in this population.

Epidemiological study of injuries in international Rugby Sevens.

Objective:To assess incidence, nature, and causes of injuries sustained in international Rugby Sevens. Design:Prospective cohort: definitions and procedures were compliant with the consensus statement for epidemiological studies in rugby union. Setting:2008/2009 International Rugby Board Sevens World Series (8 tournaments) and Rugby World Cup Sevens 2009. Participants:Two hundred ninety players, representing 12 countries. Assessment of risk factors:Injuries sustained as function of playing position and nature, cause, and time of onset. Main outcome measures:Number, location, diagnosis, severity, and cause of injuries: incidence (injuries/1000 player-hours) and severity (days absence from training/competition) of injuries. Results:One hundred four injuries were recorded during 578 team games (979.1 player-match hours), which equates to 0.18 injuries per team match, 0.96 injuries per team per tournament, or 106.2 injuries per 1000 player-hours (95% confidence interval, 87.8-128.9). These injuries had a mean severity of 45 days and a median severity of 24 days. The lower limb (70%) and joint (non-bone)/ligament (52%) were the most common site and type of injury. Most match injuries were acute (93%) and resulted from contact (78%) events; being tackled (34%) and running (22%) were the most common causes of injury. Conclusions:Results indicated that the risk of injury from international Rugby Sevens was higher than that reported for international 15-a-side rugby; in particular, the severity of injury was significantly higher. A need for further research into the reasons for the high average severity of injury and the development of injury prevention strategies for ankle and knee ligament injuries in Rugby Sevens were indicated.

LST1 and NCR3 expression in autoimmune inflammation and in response to IFN-γ, LPS and microbial infection

Many genes in the central region of the major histocompatibility complex (MHC) encode proteins involved in immune and inflammatory responses. In this study, we have further characterized two genes in the MHC class IV region, leucocyte-specific transcript (LST) 1 and natural cytotoxicity-triggering receptor 3 (NCR3) (also known as 1C7 and natural killer (NK)p30). The specific function of LST1 is not known, although expression analysis and functional data suggest an immunomodulatory role. The LST1 gene undergoes extensive alternative splicing, giving rise to both membrane-bound (encoded by exon 3) and soluble isoforms. The NCR3 protein is involved in NK-mediated cytotoxicity and plays a role in NK/dendritic cell crosstalk. Expression of these genes was examined, by real-time reverse transcriptase–polymerase chain reaction, in autoimmune-induced inflammation, specifically rheumatoid-arthritis-affected blood and synovium, and in response to stimulation with inflammatory mediators and bacterial agents. The expression of LST1, specifically splice variants encoding soluble isoforms and NCR3, was increased in rheumatoid-arthritis-affected blood and synovium and was associated with more severe inflammation in the synovium. Furthermore, both genes were significantly up-regulated in response to lipopolysaccharide, interferon (IFN)-γ and bacterial infection. These findings suggest that NCR3 and soluble isoforms of LST1 may play a role in inflammatory and infectious diseases.

Impact of the International Rugby Board's experimental law variations on the incidence and nature of match injuries in southern hemisphere professional rugby union

OBJECTIVE To examine the epidemiology of match injuries in southern hemisphere professional rugby union and assess the impact of the International Rugby Board (IRB) Experimental Law Variations. SETTING One-season whole population prospective cohort. SUBJECTS Twenty-seven teams (813 players) taking part in the 2008 Super 14 and Vodacom Cup competitions. OUTCOME MEASURES Incidence, severity, location, type and cause of injury. RESULTS The incidence in the Super 14 competition (96.3 injuries/1 000 player-match hours; 95% confidence interval (CI) 69.0 - 111.7) was significantly higher (p = 0.003) than that in the Vodacom Cup (71.2; CI 60.0 - 84.5); injury severity was significantly lower (p < 0.001) in the Super 14 (mean 13.4 days; median 5) than the Vodacom Cup (mean 21.2; median 12). There were no significant differences between the two competitions in type or location of injury: lower limb muscle/ tendon (Super 14: 27.8%; Vodacom Cup: 25.7%) and joint (non-bone)/ligament (Super 14: 18.8%; Vodacom Cup: 24.3%) were the most common injuries. Injury causation was similar for the two competitions but there were significantly fewer ruck/maul (p = 0.001) and more tackled (p = 0.010) injuries in Super 14 compared with English Premiership rugby and fewer collision (p = 0.002) and more tackling (p < 0.001) injuries compared with Rugby World Cup. In the Vodacom Cup, there were significantly more tackling (p < 0.001) injuries compared with Rugby World Cup. CONCLUSION The incidence, nature and causes of injuries in southern hemisphere professional club rugby played under IRB Experimental Law Variations were similar to those for professional club rugby in the northern hemisphere and Rugby World Cup played under the previous Laws of Rugby.