MMP3 and TIMP2 gene variants as predisposing factors for Achilles tendon pathologies: Attempted replication study in a British case-control cohort

Risk factors for Achilles tendon rupture: an updated systematic review

OBJECTIVE

Identifying risk factors for Achilles Tendon Rupture (ATR) is one of the first necessary steps for its prevention. This systematic review aimed to update the systematic review published in 2014 in ATR etiology.

METHODOLOGY

A systematic review was carried out using PubMed, EBSCO, and ScienceDirect databases. All types of research studies (Randomized Control Trials - RCTs, Cohort studies, Case-control studies and Cross-sectional studies) that considered ATR, were eligible. The inclusion criteria for eligibility of the studies were to be written in the English language, and to include populations of men and/or women, both athletes, and non-athletes, healthy individuals, and patients. Two independent reviewers used the assessment instrument Newcastle-Ottawa Scale independently, to evaluate the quality of each selected study. Further, two reviewers worked independently to extract the study characteristics, and the GRADE methodology was used to assess the level of certainty of each risk factor.

RESULTS

From 9526 studies initially identified, 19 studies were eligible for further analysis to identify risk factors for ATR. Seventeen studies were considered good quality, and two studies fair quality. Low to very low certainty of evidence was found for the following medications: steroids, quinolones, and oral bisphosphonate, as well as for other factors such as chronic tendon inflammation and Achilles' tendinopathy, spring season, diabetes, previous musculoskeletal injury, regular participation in athletic activity, hyperparathyroidism, renal failure, and genetic factors.

CONCLUSIONS

The risk factors found prove that ATR is a multifactorial injury. Appropriate methodologies and well-designed studies are needed to determine the factors and their significance in ATR risk. Finally, the role of biomechanical and psychological aspects in the ATR etiology may be of interest in future studies, as we could not extract relative data in our review.

Genome-wide association study identifying variants related to performance and injury in high-performance athletes

A growing body of evidence exists supporting the role that genetic variation plays in athletic performance and injury. This study sought to identify genetic variants associated with performance and lower limb musculoskeletal injury in a high-level athletic cohort. A total of 126 Estonian National Team members (Olympic athletes and participants of International Championships) (104 males, 82.5%) underwent a genome-wide association analysis between 2017 and 2018, to identify single-nucleotide polymorphisms (SNPs) associated with performance and/or injury. The athletic cohort was stratified within each sport based on performance and whether they were a medalist (n = 29) or not (n = 97), whether they sustained an injury (n = 47) or not (n = 79), and the type of injury (patella tendinopathy n = 22, Achilles tendinopathy n = 17, hamstring injury n = 3, anterior cruciate ligament rupture n = 6). Three SNPs demonstrated strong genome-wide association with athletic performance (podium/medalist versus not), including DSG1 (rs10502567, OR 14.3) and DSG4 (rs73410248, OR 17.4), while 76 SNPs demonstrated suggestive significance. Overall, 37 SNPs gave genome-wide suggestive association with any type of injury, including PAPPA2 (rs11580456, OR 13.8) and MAS1 (rs220735, rs170219, OR 3.1) which demonstrated positive signal with multiple SNPs. Several genes demonstrated positive association for the specific injury types, including COL22A1 (rs3924862) and PLXNA2 (rs11799530), as well as PAPPA2 (rs11580456), DOK5 (rs73142922), GNG12 (rs28435277), and DAP (rs267959, rs2930047, rs1080440, rs267939). The current study identified genetic variants associated with high-level athletic performance and musculoskeletal injury. Further work is required to permit integration of this and future knowledge into individualized training practices, as well as injury mitigation and rehabilitation programs.

Gene variants previously associated with reduced soft-tissue injury risk: Part 2 - Polygenic associations with elite status in Rugby

Part 1 of this genetic association series highlighted several genetic variants independently associated with elite status in rugby. However, it is highly likely that the genetic influence on elite status is polygenic due to the interaction of multiple genes. Therefore, the aim of the present study was to investigate whether polygenic profiles of elite rugby athletes differed from non-athletes utilising 13 genetic polymorphisms previously associated with tendon/ligament injury. Total genotype score (TGS) was calculated and multifactor dimensionality reduction (MDR) was used to calculate SNP-SNP epistasis interactions. Based on our elite rugby data from Part 1, mean TGS was significantly higher in elite rugby athletes (52.1 ± 10.7) than non-athletes (48.7 ± 10.8). There were more elite rugby athletes (54%) within the upper TGS quartile, and fewer (46%) within the lower quartile, compared to non-athletes (31% and 69%, respectively; P = 5·10^-5), and the TGS was able to distinguish between elite rugby athletes and non-athletes (area under the curve = 0.59; 95% confidence interval 0.55-0.63; P = 9·10^-7). Furthermore, MDR identified a three-SNP model of COL5A1 rs12722, COL5A1 rs3196378 and MIR608 rs4919510 that was best able to predict elite athlete status, with a greater frequency of the CC-CC-CC genotype combination in elite rugby athletes (9.8%) than non-athletes (5.3%). We propose that elite rugby athletes possess "preferable" musculoskeletal soft-tissue injury-associated polygenic profiles that have helped them achieve success in the high injury risk environment of rugby. These data may, in future, have implications for the individual management of musculoskeletal soft-tissue injury.Highlights Elite rugby athletes have preferable polygenic profiles to non-athletes in terms of genetic variants previously associated with musculoskeletal soft-tissue injury.The total genotype score was able to distinguish between elite rugby athletes and non-athletes.COL5A1 rs12722, COL5A1 rs3196378 and MIR608 rs4919510 produced the best model for predicting elite athlete status.We propose that elite rugby athletes may have an inherited advantage to achieving elite status due to an increased resistance to soft-tissue injury.

Genetic contribution to the etiology of Achilles tendon rupture. A Danish nationwide register study of twins

BACKGROUND

It is unknown if genetics contribute to the etiology of acute Achilles tendon rupture (ATR). The aims of the present study were, 1) To calculate the concordance rate for monozygotic (MZ) twins and same-sex dizygotic (SSDZ) twins and 2) to estimate the heritability of ATR.

METHODS

The study was performed as a registry study using the Danish Twin Registry and the Danish National Patient Registry.

RESULTS

The study sample consisted of 85,534 twins born from 1895 to 1995. Of these, 572 (0.67%) were registered with ATR in the period from 1994 to 2014. The concordance rate was 8.1% (95% CI 1.4-14.7%) for MZ twins and 4.3% (95% CI 0.7-7.9%) for SSDZ twins. The heritability of ATR was 47% (95% CI 31-62%).

CONCLUSION

This study found that genetics contribute substantially to the etiology of ATR with an estimated heritability of the liability to ATR of approximately 50%. The finding generates the hypothesis that genetics play a role in the pathological changes that occur in the Achilles tendon before a rupture. The risk of ATR for a twin within a 20 year period, if the co-twin has had an ATR, was 8% for MZ twins and 4% for SSDZ twins.

Challenges and perspectives of tendon-derived cell therapy for tendinopathy: from bench to bedside

Tendon is composed of dense fibrous connective tissues, connecting muscle at the myotendinous junction (MTJ) to bone at the enthesis and allowing mechanical force to transmit from muscle to bone. Tendon diseases occur at different zones of the tendon, including enthesis, MTJ and midsubstance of the tendon, due to a variety of environmental and genetic factors which consequently result in different frequencies and recovery rates. Self-healing properties of tendons are limited, and cell therapeutic approaches in which injured tendon tissues are renewed by cell replenishment are highly sought after. Homologous use of individual’s tendon-derived cells, predominantly differentiated tenocytes and tendon-derived stem cells, is emerging as a treatment for tendinopathy through achieving minimal cell manipulation for clinical use. This is the first review summarizing the progress of tendon-derived cell therapy in clinical use and its challenges due to the structural complexity of tendons, heterogeneous composition of extracellular cell matrix and cells and unsuitable cell sources. Further to that, novel future perspectives to improve therapeutic effect in tendon-derived cell therapy based on current basic knowledge are discussed.

The loop of phenotype: Dynamic reciprocity links tenocyte morphology to tendon tissue homeostasis

Cells and their surrounding extracellular matrix (ECM) are engaged in dynamic reciprocity to maintain tissue homeostasis: cells deposit ECM, which in turn presents the signals that define cell identity. This loop of phenotype is obvious for biochemical signals, such as collagens, which are produced by and presented to cells, but the role of biomechanical signals is also increasingly recognised. In addition, cell shape goes hand in hand with cell function and tissue homeostasis. Aberrant cell shape and ECM is seen in pathological conditions, and control of cell shape in micro-fabricated platforms disclose the causal relationship between cell shape and cell function, often mediated by mechanotransduction. In this manuscript, we discuss the loop of phenotype for tendon tissue homeostasis. We describe cell shape and ECM organization in normal and diseased tissue, how ECM composition influences tenocyte shape, and how that leads to the activation of signal transduction pathways and ECM deposition. We further describe the use of technologies to control cell shape to elucidate the link between cell shape and its phenotypical markers and focus on the causal role of cell shape in the loop of phenotype. STATEMENT OF SIGNIFICANCE: The dynamic reciprocity between cells and their surrounding extracellular matrix (ECM) influences biomechanical and biochemical properties of ECM as well as cell function through activation of signal transduction pathways that regulate gene and protein expression. We refer to this reciprocity as Loop of Phenotype and it has been studied and demonstrated extensively by using micro-fabricated platforms to manipulate cell shape and cell fate. In this manuscript, we discuss this concept in tendon tissue homeostasis by giving examples in healthy and pathological tenson tissue. Furthermore, we elaborate this by showing how biomaterials are used to feed this reciprocity to manipulate cell shape and function. Finally, we elucidate the link between cell shape and its phenotypical markers and focus on the activation of signal transduction pathways and ECM deposition.

Tendon and Ligament Genetics: How Do They Contribute to Disease and Injury? A Narrative Review

A significant proportion of patients requiring musculoskeletal management present with tendon and ligament pathology. Our understanding of the intrinsic and extrinsic mechanisms that lead to such disabilities is increasing. However, the complexity underpinning these interactive multifactorial elements is still not fully characterised. Evidence highlighting the genetic components, either reducing or increasing susceptibility to injury, is increasing. This review examines the present understanding of the role genetic variations contribute to tendon and ligament injury risk. It examines the different elements of tendon and ligament structure and considers our knowledge of genetic influence on form, function, ability to withstand load, and undertake repair or regeneration. The role of epigenetic factors in modifying gene expression in these structures is also explored. It considers the challenges to interpreting present knowledge, the requirements, and likely pathways for future research, and whether such information has reached the point of clinical utility.

Advances in sports genomics

Sports genomics is the scientific discipline that focuses on the organization and function of the genome in elite athletes, and aims to develop molecular methods for talent identification, personalized exercise training, nutritional need and prevention of exercise-related diseases. It postulates that both genetic and environmental factors play a key role in athletic performance and related phenotypes. This update on the panel of genetic markers (DNA polymorphisms) associated with athlete status and soft-tissue injuries covers advances in research reported in recent years, including one whole genome sequencing (WGS) and four genome-wide association (GWAS) studies, as well as findings from collaborative projects and meta-analyses. At end of 2020, the total number of DNA polymorphisms associated with athlete status was 220, of which 97 markers have been found significant in at least two studies (35 endurance-related, 24 power-related, and 38 strength-related). Furthermore, 29 genetic markers have been linked to soft-tissue injuries in at least two studies. The most promising genetic markers include HFE rs1799945, MYBPC3 rs1052373, NFIA-AS2 rs1572312, PPARA rs4253778, and PPARGC1A rs8192678 for endurance; ACTN3 rs1815739, AMPD1 rs17602729, CPNE5 rs3213537, CKM rs8111989, and NOS3 rs2070744 for power; LRPPRC rs10186876, MMS22L rs9320823, PHACTR1 rs6905419, and PPARG rs1801282 for strength; and COL1A1 rs1800012, COL5A1 rs12722, COL12A1 rs970547, MMP1 rs1799750, MMP3 rs679620, and TIMP2 rs4789932 for soft-tissue injuries. It should be appreciated, however, that hundreds and even thousands of DNA polymorphisms are needed for the prediction of athletic performance and injury risk.

Gene Variants Previously Associated with Reduced Soft Tissue Injury Risk: Part 1 - Independent Associations with Elite Status in Rugby

AbstractThere is growing evidence of genetic contributions to tendon and ligament pathologies. Given the high incidence and severity of tendon and ligament injuries in elite rugby, we studied whether 13 gene polymorphisms previously associated with tendon/ligament injury were associated with elite athlete status. Participants from the RugbyGene project were 663 elite Caucasian male rugby athletes (RA) (mean (standard deviation) height 1.85 (0.07) m, mass 101 (12) kg, age 29 (7) yr), including 558 rugby union athletes (RU) and 105 rugby league athletes. Non-athletes (NA) were 909 Caucasian men and women (56% female; height 1.70 (0.10) m, mass 72 (13) kg, age 41 (23) yr). Genotypes were determined using TaqMan probes and groups compared using Χ² and odds ratio (OR). COLGALT1 rs8090 AA genotype was more frequent in RA (27%) than NA (23%; P = 0.006). COL3A1 rs1800255 A allele was more frequent in RA (26%) than NA (23%) due to a greater frequency of GA genotype (39% vs 33%). For MIR608 rs4919510, RA had 1.7 times the odds of carrying the CC genotype compared to NA. MMP3 rs591058 TT genotype was less common in RA (25.1%) than NA (31.2%; P < 0.04). For NID1 rs4660148, RA had 1.6 times the odds of carrying the TT genotype compared to NA. It appears that elite rugby athletes have an inherited advantage that contributes to their elite status, possibly via resistance to soft tissue injury. These data may, in future, assist personalized management of injury risk amongst athletes.

Association between matrix metalloproteinase-3 gene polymorphisms and tendon-ligament injuries: evidence from a meta-analysis

Background

Tendon-ligament injuries (TLIs), including Achilles tendinopathy, cruciate ligament injury, tennis elbow, rotator cuff injury, patellar tendinopathy, and tibial tendinopathy, are common musculoskeletal soft injuries during physical activity. Matrix metalloproteinase-3 (MMP-3) gene polymorphisms have been implicated in the etiology of TLIs in several genetic association studies with inconsistent results. The purpose of this study was to collect and synthesize the current evidences on the association of MMP-3 polymorphisms and TLIs.

Methods

The search was conducted using PubMed, Web of Science, EMBASE, Cochrane Library, CNKI and Wanfang databases, prior to July, 2021. Newcastle Ottawa Scale was used to appraise the study quality. Strengths of association were represented by odds ratios (ORs) and 95% confidence intervals (95% CIs).

Results

Thirteen studies with 2871 cases and 4497 controls met the eligibility criteria, and each study was in high quality. The overall analyzes suggested rs3025058 was associated with an increased TLIs risk (5A vs. 6A, OR = 1.20, 95% CI 1.03–1.40, P = 0.020). However, the association was not found for rs679620, rs591058, and rs650108 polymorphisms. Subgroup analysis by injury type suggested that rs679620 polymorphism was associated with a reduced risk to Achilles tendon rupture (AA + AG vs. GG, OR = 0.46, 95% CI 0.25–0.87, P = 0.020), and rs3025058 was associated with an elevated risk to anterior cruciate ligament injury (5A5A + 5A6A vs. 6A6A, OR = 1.46, 95% CI 1.03–2.06, P = 0.030). When stratified by ethnicity, the findings indicated that rs3025058 polymorphism was associated with an increased TLIs risk among Caucasians (5A6A vs. 6A6A, OR = 1.55, 95% CI 1.09–2.42, P = 0.020) and Brazilians (5A5A vs. 5A6A + 6A6A, OR = 2.80, 95% CI 1.44–5.45, P = 0.002).

Conclusion

Findings of this study suggest that rs679620 polymorphism is associated with a reduced Achilles tendon rupture risk, and rs3025058 polymorphism contributes to an increased TLIs risk in Caucasians and Brazilians. However, rs591058 and rs650108 polymorphisms do not show any association with TLIs.

Identification of Three Loci Associated with Achilles Tendon Injury Risk from a Genome-wide Association Study

PURPOSE

This study aimed to screen the entire genome for genetic markers associated with risk for Achilles tendon injury.

METHODS

A genome-wide association analysis was performed using data from the Kaiser Permanente Research Board and the UK Biobank. Achilles tendon injury cases were identified based on electronic health records from the Kaiser Permanente Research Board databank and the UK Biobank from individuals of European ancestry. Genome-wide association analyses from both cohorts were tested for Achilles tendon injury using a logistic regression model adjusting for sex, height, weight, and race/ethnicity using allele counts for single nucleotide polymorphisms (SNP). Previously identified genes within the literature were also tested for association with Achilles tendon injury.

RESULTS

There were a total of 12,354 cases of Achilles tendon injury and 483,080 controls within the two combined cohorts, with 67 SNP in three chromosomal loci demonstrating a genome-wide significant association with Achilles tendon injury. The first locus contains a single SNP (rs183364169) near the CDCP1 and TMEM158 genes on chromosome 3. The second locus contains 65 SNP in three independently segregating sets near the MPP7 gene on chromosome 10. The last locus contains a single SNP (rs4454832) near the SOX21 and GPR180 genes on chromosome 13. The current data were used to test 14 candidate genes previously reported to show an association with Achilles tendon injury, but none showed a significant association (all P > 0.05).

CONCLUSION

Three loci were identified as potential risk factors for Achilles tendon injury and deserve further validation and investigation of molecular mechanisms.

Matrix Metalloproteinase Genes (MMP1, MMP10, MMP12) on Chromosome 11q22 and the Risk of Non-Contact Anterior Cruciate Ligament Ruptures

Background: Sequence variants within the matrix metalloproteinases genes remain plausible biological candidates for further investigation of anterior cruciate ligament (ACL) rupture risk. The aim of the present study was to establish whether variants within the MMP1 (rs1799750, ->G), MMP10 (rs486055, C > T) and MMP12 (rs2276109, T > C) genes were associated with non-contact ACL rupture in a Polish cohort. Methods: The unrelated, self-reported Polish Caucasian participants consisted of 228 (157 male) individuals with primary non-contact ACL rupture and 202 (117 male) participants without any history of ACL rupture. All samples were genotyped in duplicate using the Applied Biosystems TaqMan^® methodology. The statistical analyses were involved in determining the distribution of genotype and allele frequencies for the investigated polymorphisms between the diagnostic groups. Furthermore, pseudo-haplotypes were constructed to assess possible gene–gene interactions. Results: All genotype frequencies in the ACL rupture and control groups conformed to Hardy Weinberg Equilibrium expectations. None of the polymorphisms were associated with risk of non-contact ACL rupture under the codominant, dominant, recessive and over-dominant genetic models. Likewise, no genotype–genotype combinations inferred as “haplotypes” as a proxy of gene–gene interactions were associated with the risk of non-contact ACL ruptures. Conclusions: Despite the fact that the current study did not support existing evidence suggesting that variants within the MMP1, MMP10, and MMP12 genes influence non-contact ACL rupture risk, future work should include high-throughput sequencing technologies to identify potential targeted polymorphisms to fully characterize the 11q22 region with susceptibility to non-contact ACL rupture susceptibility in a Polish cohort.

Association of the matrix metalloproteinase 3 (MMP3) single nucleotide polymorphisms with tendinopathies: case-control study in high-level athletes

BACKGROUND

Matrix metalloproteinases (MMPs) play an important role in matrix remodelling, as well as in tendon integrity. Due to overuse, athletes often develop chronic tendinopathies. If not treated, they lead to severe impairment, even complete tendon ruptures.

AIM

The main purpose of this study was to investigate whether three functional polymorphisms within the MMP3 gene are associated with increased risk of developing tendinopathies in high-level Croatian athletes.

METHODS

We have recruited one hundred fifty-five (63 high-level athletes with diagnosed tendinopathies and 92 asymptomatic controls) unrelated Caucasians for this case-control genetic study. All participants were genotyped for three single nucleotide polymorphisms (SNP) within the MMP3 gene: rs591058 C/T, rs650108 A/G and rs679620 G/A using the pyrosequencing method.

RESULTS

The MMP3 rs650108 GG (P = 0.0074) and rs679620 AA (P = 0.0119) genotypes were significantly over-represented in cases compared with controls, while rs591058 TT (P = 0.0759), as well as haplotype variant T - G - A (P = 0.06), implicated that there is an indication of predisposition for tendinopathies.

CONCLUSION

These results support association between functional variants within the MMP3 gene and the risk of tendinopathies in high-level athletes. Further research is needed to replicate these results in a larger population.

Age is a risk factor for contralateral tendon rupture in patients with acute Achilles tendon rupture

PURPOSE

Rupture of the contralateral Achilles tendon following Achilles tendon rupture can lead to devastating outcomes. However, despite the clinical importance, the risk factors and incidence of contralateral Achilles tendon rupture have not been well studied. This study aimed to determine the incidence of contralateral tendon rupture after Achilles tendon rupture and to identify associated patient characteristics.

METHODS

Medical records for 226 consecutive patients with Achilles tendon rupture were retrospectively reviewed. The occurrence of contralateral Achilles tendon rupture and patient characteristics were determined through review of medical records and telephone surveys.

RESULTS

The cumulative incidences of contralateral Achilles tendon rupture at 1, 3, 5, and 7 years after Achilles tendon rupture were 0.4%, 1.8%, 3.4%, and 5.1%, respectively. The only statistically significant risk factor was age between 30 and 39 years at the time of initial Achilles tendon rupture (hazard ratio = 4.9).

CONCLUSIONS

Patients who sustain Achilles tendon rupture in their 30 s have significantly increased risk for contralateral tendon rupture.

LEVEL OF EVIDENCE

III.

Rotator Cuff Tear Susceptibility Is Associated With Variants in Genes Involved in Tendon Extracellular Matrix Homeostasis

Rotator cuff tears (RCT) is a multifactorial disease with genetic factors contributing for the disease etiology. We hypothesized that genetic variants in genes involved in extracellular matrix (ECM) homeostasis may alter susceptibility to RCT. We evaluated 20 polymorphisms of genes involved in ECM homeostasis in 211 cases of full-thickness tears of the supraspinatus (N_females  = 130; N_males  = 81) and 567 age-matched controls (N_females  = 317; N_males  = 250). Multivariate logistic regressions were carried out with age, gender, genetic ancestry (based on the analysis of 61 biallelic short insertion/deletion polymorphisms), and common co-morbidities (diabetes, dyslipidemia, and smoking habits) as covariates. We observed that carriers of the rare allele of both studied variants of TGFB1, as well as their G/A (rs1800470/rs1800469) haplotype, were less susceptible to RCT (p < 0.05). In contrast, carriers of the G allele of MMP9 rs17576 (p = 0.014) or G/G haplotype (rs17576/rs17577; p < 0.001) had an increased risk for tendon tears. The presence of the T allele of MMP2 rs2285053 (p = 0.033), the T allele of MMP3 rs679620 (p = 0.024), and the TT-genotype of TIMP2 rs2277698 (p = 0.01) was associated with susceptibility to tears, especially in females. In males, the A allele of COL5A1 rs3196378 (p = 0.032) and the G allele of TGFBR1 rs1590 (p = 0.039) were independent risk factors for RCT. The C/T COL5A1 (rs3196378/rs11103544) haplotype was associated with a reduced risk of tears in males (p = 0.03). In conclusion, we identified the genetic variants associated with RCT susceptibility, thereby reinforcing the role of genes involved in the structure and homeostasis of the ECM of tendons in disease development. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:192-201, 2020.

Relationship of common variants in MPP7, TIMP2 and CASP8 genes with the risk of chronic achilles tendinopathy

Previous etiologic studies have indicated that both environmental and genetic factors play important roles in the occurrence and development of chronic Achilles tendinopathy (AT). A recent study documented the results of the largest genome-wide association study for chronic AT to date, indicating that MPP7, TIMP2 and CASP8 may be involved in the occurrence and development of chronic AT. In this study, we aimed to investigate whether MPP7, TIMP2 and CASP8 were associated with susceptibility to chronic AP in a Han Chinese population. A total of 3,680 study subjects comprised 1,288 chronic AT cases, and 2,392 healthy controls were recruited. Forty-four tag SNPs (7 from CASP8, 20 from MPP7, and 17 from TIMP2) were genotyped in the study. Genetic association analyses were performed at both single marker and haplotype levels. Functional consequences of significant SNPs were examined in the RegulomeDB and GTEx databases. Two SNPs, SNP rs1937810 (OR [95%CI] = 1.20 [1.09-1.32], χ2 = 13.50, P = 0.0002) in MPP7 and rs4789932 (OR [95%CI] = 1.24 [1.12-1.37], χ2 = 17.98, P = 2.23 × 10-5) in TIMP2, were significantly associated with chronic AT. Significant eQTL signals for SNP rs4789932 on TIMP2 were identified in human heart and artery tissues. Our results provide further supportive evidence for the association of the TIMP2 and MPP7 genes with chronic AT, which supports important roles for TIMP2 and MPP7 in the etiology of chronic AT, adding to the current understanding of the susceptibility of chronic AT.

Variability within the human iNOS gene and Achilles tendon injuries: Evidence for a heterozygous advantage effect

OBJECTIVES

The aim of this case control genetic association study was to explore whether two variants within the inducible nitric oxide synthase (iNOS) gene, rs2779249 (C/A) and rs2248814 (A/G), influenced the risk of Achilles tendinopathy in a British population.

DESIGN

Candidate gene, case control association study.

METHOD

We recruited 145 individuals diagnosed with Achilles tendon pathology and 132 asymptomatic controls. All participants were genotyped for the iNOS variants using qPCR and significant associations were discovered using a combination of Chi squared and ANOVA type analysis.

RESULTS

The CA genotype of the iNOS rs2779249 variant was protective and conformed to a heterozygous advantage model of inheritance as it was overrepresented in the control participants (p=0.009). In sex specific analysis the protective association persisted in male participants (p=0.016) but not in females. Unlike the rs2779249 variant, the rs2248814 variant was not associated with Achilles tendinopathy or Achilles tendon rupture.

CONCLUSION

The rs2779249 CA genotype within the human iNOS gene appears to protect individuals from Achilles tendinopathy. This study further supports a genetic contribution to modifying the risk of Achilles tendon problems. The study also infers an important role for nitric oxide in tendon healing and/or degradation.

Additional evidence supports association of common genetic variants in MMP3 and TIMP2 with increased risk of chronic Achilles tendinopathy susceptibility

OBJECTIVES

To systematically evaluate the effects of matrix metalloproteinase-3 (MMP3) and tissue inhibitor of metalloproteinase-2 (TIMP2) on chronic Achilles tendinopathy (AT) susceptibility. Chronic AT is one of the most prevalent and severe injuries in athletes. Early studies suggested that tendon extracellular matrix (ECM) may be involved in the pathogenesis of chronic AT. MMP3 is an important member of the MMP family and is important to ECM integrity. In addition, tissue inhibitor of metalloproteinase-2 (TIMP2) can indirectly limit the activity of MMP3 activity.

DESIGN

Case-control genetic association study.

METHODS

A total of 1084 chronic AT patients and 2188 controls with Chinese Han ancestry were recruited. Twenty-one SNPs, 4 mapped to MMP3 and 17 mapped to TIMP2, were selected and genotyped. Genetic association analyses and eQTL analyses were performed. In addition, we also examined the potential effects of epistasis using a case-only study design.

RESULTS

Two SNPs, rs679620 (OR=0.82, P=0.0006, MMP3) and rs4789932 (OR=1.2, P=0.0002, TIMP2) were identified to be significantly associated with chronic AT risk. No significant results were obtained from epistasis analyses. SNP rs4789932 was identified to be strongly associated with the gene expression level of TIMP2 in two types of human tissues: atrial appendage (P=0.0003) and tibial artery (P=0.0009).

CONCLUSIONS

We have identified genetic polymorphisms in MMP3 and TIMP2 to be significantly associated with chronic AT risk. Further eQTL analyses indicated that SNP rs4789932 of TIMP2 was related to the gene expression levels of TIMP2. These results suggest important roles for MMP3 and TIMP2 in the pathophysiology of chronic AT.

Tendon and Ligament Injuries in Elite Rugby: The Potential Genetic Influence

This article reviews tendon and ligament injury incidence and severity within elite rugby union and rugby league. Furthermore, it discusses the biological makeup of tendons and ligaments and how genetic variation may influence this and predisposition to injury. Elite rugby has one of the highest reported injury incidences of any professional sport. This is likely due to a combination of well-established injury surveillance systems and the characteristics of the game, whereby high-impact body contact frequently occurs, in addition to the high intensity, multispeed and multidirectional nature of play. Some of the most severe of all these injuries are tendon and ligament/joint (non-bone), and therefore, potentially the most debilitating to a player and playing squad across a season or World Cup competition. The aetiology of these injuries is highly multi-factorial, with a growing body of evidence suggesting that some of the inter-individual variability in injury susceptibility may be due to genetic variation. However, little effort has been devoted to the study of genetic injury traits within rugby athletes. Due to a growing understanding of the molecular characteristics underpinning the aetiology of injury, investigating genetic variation within elite rugby is a viable and worthy proposition. Therefore, we propose several single nucleotide polymorphisms within candidate genes of interest; COL1A1, COL3A1, COL5A1, MIR608, MMP3, TIMP2, VEGFA, NID1 and COLGALT1 warrant further study within elite rugby and other invasion sports.

Epigenetic Status of The Human MMP11 Gene Promoter is Altered in Patellar Tendinopathy

Patellar tendinopathy (PT) is a debilitating condition that often affects those who are physically active. Gene variation is known to contribute to human tendinopathy but the role of DNA methylation, as an epigenetic factor, has only recently been discovered. Using a case-control approach, we sought to determine whether differences existed between the methylation status of the MMP11 gene promoter in patellar tendinopathy compared to healthy tendon. We used PCR and pyrosequencing to interrogate the methylation profiles of 4 CpG sites (areas of the genome rich in C/G nucleotides) upstream of the MMP11 gene in DNA from males with PT (n = 10) and those with healthy tendon (n = 10). We also conducted a correlation analysis to establish whether age influenced methylation in the PT patients and controls. We found a significant (p = 0.045) difference in the methylation status of a single CpG site 65 base pairs (bp) upstream of the MMP11 promoter between the PT group and controls. There were no other differences in the extent of MMP11 promoter methylation between the two groups. Interestingly, we also found that in controls the degree of methylation at a second CpG site, 55 bp upstream of the first exon, tentatively correlated (r = 0.77, p = 0.009) with age. However, the correlation did not reach significance when a potential outlier was removed. This is the first study to show an epigenetic alteration to a member of the MMP gene family in human patellar tendinopathy. The data add to our understanding of how epigenetics should be considered when developing appropriate risk models.

Clinical risk factors for Achilles tendinopathy: a systematic review

Background

Achilles tendinopathy is a common problem, but its exact aetiology remains unclear.

Objective

To evaluate the association between potential clinical risk factors and Achilles tendinopathy.

Design

Systematic review.

Data sources

The databases Embase, MEDLINE Ovid, Web of Science, Cochrane Library and Google Scholar were searched up to February 2018.

Eligibility criteria

To answer our research question, cohort studies investigating risk factors for Achilles tendinopathy in humans were included. We restricted our search to potential clinical risk factors (imaging studies were excluded).

Results

We included 10 cohort studies, all with a high risk of bias, from 5111 publications identified. There is limited evidence for nine risk factors: (1) prior lower limb tendinopathy or fracture, (2) use of ofloxacin (quinolone) antibiotics, (3) an increased time between heart transplantation and initiation of quinolone treatment for infectious disease, (4) moderate alcohol use, (5) training during cold weather, (6) decreased isokinetic plantar flexor strength, (7) abnormal gait pattern with decreased forward progression of propulsion, (8) more lateral foot roll-over at the forefoot flat phase and (9) creatinine clearance of <60 mL/min in heart transplant patients. Twenty-six other putative risk factors were not associated with Achilles tendinopathy, including being overweight, static foot posture and physical activity level.

Conclusion

From an ocean of studies with high levels of bias, we extracted nine clinical risk factors that may increase a person’s risk of Achilles tendinopathy. Clinicians may consider ofloxacin use, alcohol consumption and a reduced plantar flexor strength as modifiable risk factors when treating patients with Achilles tendinopathy.

Trial registration number

CRD42017053258.

Are MMP3, MMP8 and TIMP2 gene variants associated with anterior cruciate ligament rupture susceptibility?

OBJECTIVES

Anterior cruciate ligament rupture (ACLR) is a common and severe knee injury which typically occurs as a result of sports participation, primarily via a non-contact mechanism. A number of extrinsic and intrinsic risk factors, including genetics, have been identified thus far. Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteases (TIMPs) play a crucial role in extracellular matrix remodeling of ligaments and therefore the genes encoding MMPs and TIMPs are plausible candidates for investigation with ACL rupture risk.

DESIGN

A case-control genetic association study was conducted on 229 (158 male) individuals with surgically diagnosed primary ACLR, ruptured through non-contact mechanisms and 192 (107 male) apparently healthy participants (CON) without any history of ACLR. All participants were physically active, unrelated, self-reported Caucasians.

METHODS

All participants were genotyped for four single nucleotide polymorphisms (SNP): MMP3 (rs591058C/T, rs679620 G/A), MMP8 (rs11225395C/T), and TIMP2 (rs4789932 G/A) using standard PCR assays. Gene-gene interactions were inferred. Single-locus association analysis was conducted using the Chi-square test. SNP-SNP interaction effects were analysed using multifactor dimensionality reduction (MDR) method.

RESULTS

Genotype frequencies did not significantly differ between cases and controls, however, the MMP3 rs679620 G and rs591058C alleles were significantly overrepresented in cases compared to controls (p=0.021, OR=1.38, 95% CI: 1.05-1.81).

CONCLUSIONS

These results support the hypothesis that genetic variation within MMP3 contributes to inter-individual susceptibility to non-contact ACLR. However, these results need to be explored further in larger, independent sample sets.

Effect of micro-RNA on tenocytes and tendon-related gene expression: A systematic review

The purpose of the review was to synthesize the current literature regarding the effect of miRNA on biological processes known to be involved in tendon and tenocyte development and homeostasis. Using multiple databases, a systematic review was performed with a customized search term crafted to identify any study examining micro-RNA in relation to tendon and/or tenocytes. Results were classified based on the following categories: Gene expression, tenocyte development and differentiation, tendon tissue repair, and tenocyte senescence. A total of 3,112 potentially relevant studies were reviewed, and after exclusion criteria was applied, 15 investigations were included in the final analysis. There were 14 specific miRNA included in this review, with 11 studies reporting on tendon-related gene expression, five reporting on tendon development and/or tenocyte differentiation, six reporting on tendon tissue repair, and five reporting on tenocyte senescence. The miR-29 family was the most commonly reported micro-RNA in the investigation. We also report on a number of micro-RNA which are associated with both positive and negative effects on tendon homeostasis. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2823-2829, 2018.

Achilles Pain, Stiffness, and Muscle Power Deficits: Midportion Achilles Tendinopathy Revision 2018

The Orthopaedic Section of the American Physical Therapy Association (APTA) has an ongoing effort to create evidence-based practice guidelines for orthopaedic physical therapy management of patients with musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability, and Health (ICF). The purpose of these revised clinical practice guidelines is to review recent peer-reviewed literature and make recommendations related to midportion Achilles tendinopathy. J Orthop Sports Phys Ther 2018;48(5):A1-A38. doi:10.2519/jospt.2018.0302.

Genetic Factors in Tendon Injury: A Systematic Review of the Literature

BACKGROUND

Tendon injury such as tendinopathy or rupture is common and has multiple etiologies, including both intrinsic and extrinsic factors. The genetic influence on susceptibility to tendon injury is not well understood.

PURPOSE

To analyze the published literature regarding genetic factors associated with tendon injury.

STUDY DESIGN

Systematic review; Level of evidence, 3.

METHODS

A systematic review of published literature was performed in concordance with the Preferred Reporting Items of Systematic Reviews and Meta-analysis (PRISMA) guidelines to identify current evidence for genetic predisposition to tendon injury. PubMed, Ovid, and ScienceDirect databases were searched. Studies were included for review if they specifically addressed genetic factors and tendon injuries in humans. Reviews, animal studies, or studies evaluating the influence of posttranscription factors and modifications (eg, proteins) were excluded.

RESULTS

Overall, 460 studies were available for initial review. After application of inclusion and exclusion criteria, 11 articles were ultimately included for qualitative synthesis. Upon screening of references of these 11 articles, an additional 15 studies were included in the final review, for a total of 26 studies. The genetic factors with the strongest evidence of association with tendon injury were those involving type V collagen A1, tenascin-C, matrix metalloproteinase-3, and estrogen-related receptor beta.

CONCLUSION

The published literature is limited to relatively homogenous populations, with only level 3 and level 4 data. Additional research is needed to make further conclusions about the genetic factors involved in tendon injury.

Biomedical Risk Factors of Achilles Tendinopathy in Physically Active People: a Systematic Review

Background

Achilles tendinopathy is the most prevalent tendon disorder in people engaged in running and jumping sports. Aetiology of Achilles tendinopathy is complex and requires comprehensive research of contributing risk factors. There is relatively little research focussing on potential biomedical risk factors for Achilles tendinopathy. The purpose of this systematic review is to identify studies and summarise current knowledge of biomedical risk factors of Achilles tendinopathy in physically active people.

Methods

Research databases were searched for relevant articles followed by assessment in accordance with PRISMA statement and standards of Cochrane collaboration. Levels of evidence and quality assessment designation were implemented in accordance with OCEBM levels of evidence and Newcastle-Ottawa Quality Assessment Scale, respectively.

Results

A systematic review of the literature identified 22 suitable articles. All included studies had moderate level of evidence (2b) with the Newcastle-Ottawa score varying between 6 and 9. The majority (17) investigated genetic polymorphisms involved in tendon structure and homeostasis and apoptosis and inflammation pathways.

Overweight as a risk factor of Achilles tendinopathy was described in five included studies that investigated non-genetic factors. COL5A1 genetic variants were the most extensively studied, particularly in association with genetic variants in the genes involved in regulation of cell-matrix interaction in tendon and matrix homeostasis. It is important to investigate connections and pathways whose interactions might be disrupted and therefore alter collagen structure and lead to the development of pathology. Polymorphisms in genes involved in apoptosis and inflammation, and Achilles tendinopathy did not show strong association and, however, should be considered for further investigation.

Conclusions

This systematic review suggests that biomedical risk factors are an important consideration in the future study of propensity to the development of Achilles tendinopathy. The presence of certain medical comorbidities and genetic markers should be considered when contemplating the aetiology of Achilles tendinopathy. Further elucidation of biomedical risk factors will aid in the understanding of tendon pathology and patient risk, thereby informing prevention and management strategies for Achilles tendinopathy.

Trial Registration

PROSPERO CRD42016036558

TIMP-2 SNPs rs7342880 and rs4789936 are linked to risk of knee osteoarthritis in the Chinese Han Population

This study aimed to investigate whether functional polymorphisms in the tissue inhibitors of metalloproteinase-2 (TIMP-2) gene are associated with susceptibility to knee osteoarthritis (OA) in the Chinese Han population. Six TIMP-2 single nucleotide polymorphisms (SNPs) were assayed using MassARRAY in 300 patients clinically and radiographically diagnosed with knee OA and in 428 controls. Allelic and genotypic frequencies were compared between groups. Logistic regression adjusting for age and gender was used to estimate risk associations between specific genotypes and knee OA by computing odds ratios (ORs) and 95% confidence intervals (95% CIs). We found that allele "A" in rs7342880 was significantly associated with increased risk of knee OA (OR = 1.44, 95%CI = 1.09-1.91, p = 0.035). In addition, in the over-dominant model, rs4789936 correlated with reduced risk of knee OA, adjusting for age and gender (OR = 0.69, 95%CI = 0.49-0.98, p = 0.036). Finally, rs7342880 correlated with increased risk of knee OA in females. This study provides evidence that TIMP-2 is a knee OA susceptibility gene in the Chinese population and a potential diagnostic and preventive marker for the disease.