Arthroscopic treatment for anterolateral impingement of the ankle: Systematic review and exploration of evidence about role of ankle instability.

BACKGROUND: Arthroscopic debridement is a common surgical treatment for patients with anterolateral impingement (ALI) of the ankle. Although they often have a history of ankle sprain, information regarding the role of ankle instability in ALI is limited. The aims of this review were to: 1) assess the clinical outcomes of arthroscopic surgical treatment for ALI of the ankle; and 2) review the data regarding anterior talofibular ligament (ATFL) injury and lateral ankle instability in patients who underwent arthroscopic surgery for ALI. METHOD: A literature search of Pubmed and EMBASE was performed. Studies that met the following inclusion criteria were reviewed: (1) human clinical studies investigating patients who underwent arthroscopic surgery for ALI; (2) results with at least one scoring system with minimum follow-up of six months. The quality of each study was evaluated using the Oxford CEBM tool to assess the level of evidence and the grade of recommendation. The data of patient characteristics, intraoperative findings and clinical outcomes were extracted. RESULTS: Eight articles were included in this systematic review, all of which were graded level 4 with grade C recommendation. In total, 203 patients with a mean age of 32 years (ranging from 11 to 74) were analysed. AOFAS score was used in 6 studies and scored 90.1 on average at follow-up. Two other studies used original scores. One study reported arthroscopic findings of the ATFL and another study reported on residual instability after surgery. New ankle sprains during follow-up period were reported in 8.3 to 20.0% of patients in 4 studies. DISCUSSION: This review showed good clinical results of arthroscopic debridement with a grade C recommendation. Reports regarding arthroscopic observation of the ATFL and residual instability after surgery were lacking. Further investigation of what we are still calling "ALI" should be made with higher level of evidence focusing more on ATFL injury and its effect on clinical outcomes.

All-inside endoscopic anatomic reconstruction leads to satisfactory functional outcomes in patients with chronic ankle instability.

PURPOSE: Ankle sprain is a common injury that can be treated conservatively, though many injured patients do not seek treatment or are not adequately managed, both of which can lead to subsequent chronic ankle instability (CAI). The purpose of this study was to evaluate the functional scores and complication rates of an all-inside anatomic reconstruction technique to treat CAI at a minimum follow-up of 24 months. METHODS: The authors retrospectively collected the records of 41 patients that underwent all-inside endoscopic anatomic reconstruction of the ATFL and CFL including demographics, complications, satisfaction, American Orthopaedic Foot and Ankle Society (AOFAS) score, Karlsson score, and ankle activity score (AAS), at a minimum follow-up of 24 months. RESULTS: The study cohort, comprised 34 patients aged 35.6 ± 10.8 years, were assessed at 48.7 ± 19.0 months. AOFAS scores improved from 60.3 ± 11.9 to 94.3 ± 6.2 postoperatively. Karlsson scores improved from 49.0 ± 10.9 to 87.2 ± 10.1 postoperatively. Thirty-three (97%) patients returned to the same AAS (5.6 ± 3.1) and rated their overall satisfaction ≥ 7. One patient (3%) was reoperated to treat a hematoma, while five patients (15%) were reoperated to remove the cortical fixation device that caused discomfort. CONCLUSION: The novel all-inside endoscopic technique for anatomic reconstruction of the ATFL and CFL grants satisfactory functional outcomes at a minimum of 24 months, and the improvements in AOFAS and Karlsson scores compared favourably to those reported for other techniques in the literature. LEVEL OF EVIDENCE: IV.

All-Inside Endoscopic Broström-Gould Technique.

Ankle sprain is the most frequent sports trauma. Surgical treatment is needed in case of chronical instability, after failure of conservative treatment. The technique established today worldwide consists in repairing the ligament (Broström technique) and strengthening the repair by adding extensor retinaculum (Gould technique). An arthroscopic technique recently has been developed; nevertheless, no published technique has proposed a total endoscopic Broström technique associated with a Gould augmentation because of difficulty in visualizing the retinaculum by anterior ankle arthroscopy. Lateral ankle endoscopy can provide a view of this area that is superior to open surgery. In this technique, the procedure is able to be performed safely and reproducible under perfect viewing. The purpose of this study is to describe an all-inside endoscopic Broström-Gould technique.

Arthroscopic classification of chronic anterior talo-fibular ligament lesions in chronic ankle instability.

BACKGROUND: The surgical treatment of chronic ankle instability (CAI) relies chiefly on anterior talo-fibular ligament (ATFL) repair (with or without augmentation) or anatomical reconstruction with a tendon graft. Arthroscopy enables not only a complete assessment and the same-stage treatment of concomitant articular lesions, but also an accurate assessment of ligament lesions. Pre-operative imaging studies (MRI, CT, US) may fail to provide sufficient detail about chronic ATFL lesions to guide the decision between repair and reconstruction. The aim of this study was to develop an arthroscopic classification of chronic ATFL lesions designed to assist in selecting the optimal surgical technique. MATERIAL AND METHODS: Sixty-nine anterior ankle arthroscopy videos recorded before surgery for CAI were studied retrospectively. ATFL dissection was performed in all patients. Based on the video analysis, five ATFL grades were identified: 0, normal ATFL thickness and tension; 1, ATFL distension with normal thickness; 2, ATFL avulsion with normal thickness; 3, thin ATFL with no resistance during the hook test; and 4, no ATFL, with a bald malleolus. Intra- and interobserver reproducibility of the arthroscopic classification of chronic ATFL lesions was evaluated by computing the kappa coefficients (κ) after assessment by two independent observers. RESULTS: All 69 ATFLs were classified as abnormal (none was grade 0). Each ATFL could be matched to a grade. Intra-observer agreement was good for both observers: κ was 0.67 with 75% of agreement for one observer and 0.68 with 76% of agreement for the other observer. Inter-observer agreement was fair to good, with κ values ranging from 0.59 to 0.88 and agreement from 70% to 91%. DISCUSSION: Arthroscopic ATFL dissection is a simple procedure that provides a highly accurate assessment of ATFL lesions and mechanical resistance, focussing chiefly on the superior ATFL. Grade 1 and 2 lesions can be repaired using the Broström-Gould procedure, whereas grade 3 and 4 lesions require anatomic reconstruction with grafting. CONCLUSION: This arthroscopic classification of chronic ATFL lesions confirms the diagnostic role for arthroscopy in assessing the ligaments in patients with CAI. It is helpful for determining the best surgical technique for stabilising the ankle. These results must be confirmed in a larger study.

Mice Deficient in Angiopoietin-like Protein 2 (Angptl2) Gene Show Increased Susceptibility to Bacterial Infection Due to Attenuated Macrophage Activity.

Macrophages play crucial roles in combatting infectious disease by promoting inflammation and phagocytosis. Angiopoietin-like protein 2 (ANGPTL2) is a secreted factor that induces tissue inflammation by attracting and activating macrophages to produce inflammatory cytokines in chronic inflammation-associated diseases such as obesity-associated metabolic syndrome, atherosclerosis, and rheumatoid arthritis. Here, we asked whether and how ANGPTL2 activates macrophages in the innate immune response. ANGPTL2 was predominantly expressed in proinflammatory mouse bone marrow-derived differentiated macrophages (GM-BMMs) following GM-CSF treatment relative to anti-inflammatory cells (M-BMMs) established by M-CSF treatment. Expression of the proinflammatory markers IL-1ß, IL-12p35, and IL-12p40 significantly decreased in GM-BMMs from Angptl2-deficient compared with wild-type (WT) mice, suggestive of attenuated proinflammatory activity. We also report that ANGPTL2 inflammatory signaling is transduced through integrin α5ß1 rather than through paired immunoglobulin-like receptor B. Interestingly, Angptl2-deficient mice were more susceptible to infection with Salmonella enterica serovar Typhimurium than were WT mice. Moreover, nitric oxide (NO) production by Angptl2-deficient GM-BMMs was significantly lower than in WT GM-BMMs. Collectively, our findings suggest that macrophage-derived ANGPTL2 promotes an innate immune response in those cells by enhancing proinflammatory activity and NO production required to fight infection.

ANGPTL2 increases bone metastasis of breast cancer cells through enhancing CXCR4 signaling.

Bone metastasis of breast cancer cells is a major concern, as it causes increased morbidity and mortality in patients. Bone tissue-derived CXCL12 preferentially recruits breast cancer cells expressing CXCR4 to bone metastatic sites. Thus, understanding how CXCR4 expression is regulated in breast cancer cells could suggest approaches to decrease bone metastasis of breast tumor cells. Here, we show that tumor cell-derived angiopoietin-like protein 2 (ANGPTL2) increases responsiveness of breast cancer cells to CXCL12 by promoting up-regulation of CXCR4 in those cells. In addition, we used a xenograft mouse model established by intracardiac injection of tumor cells to show that ANGPTL2 knockdown in breast cancer cells attenuates tumor cell responsiveness to CXCL12 by decreasing CXCR4 expression in those cells, thereby decreasing bone metastasis. Finally, we found that ANGPTL2 and CXCR4 expression levels within primary tumor tissues from breast cancer patients are positively correlated. We conclude that tumor cell-derived ANGPTL2 may increase bone metastasis by enhancing breast tumor cell responsiveness to CXCL12 signaling through up-regulation of tumor cell CXCR4 expression. These findings may suggest novel therapeutic approaches to treat metastatic breast cancer.

Angiopoietin-like protein 2 renders colorectal cancer cells resistant to chemotherapy by activating spleen tyrosine kinase-phosphoinositide 3-kinase-dependent anti-apoptotic signaling.

Angiopoietin-like protein 2 (ANGPTL2) plays an important role in inflammatory carcinogenesis and tumor metastasis by activating tumor angiogenesis and tumor cell chemotaxis and invasiveness. However, it is unclear whether ANGPTL2 expression has an effect on tumor cell survival. Here, we explored that possibility by determining whether ANGPTL2 expression altered survival of human colorectal cancer cell lines treated with antineoplastic drugs. To do so, we generated SW480 cells expressing ANGPTL2 (SW480/ANGPTL2) and control (SW480/Ctrl) cells. Apoptosis induced by antineoplastic drug treatment was significantly decreased in SW480/ANGPTL2 compared to control cells. Expression of anti-apoptotic BCL-2 family genes was upregulated in SW480/ANGPTL2 compared to SW480/Ctrl cells. To assess signaling downstream of ANGPTL2 underlying this effect, we carried out RNA sequencing analysis of SW480/ANGPTL2 and SW480/Ctrl cells. That analysis, combined with in vitro experiments, indicated that Syk-PI3K signaling induced expression of BCL-2 family genes in SW480/ANGPTL2 cells. Furthermore, ANGPTL2 increased its own expression in a feedback loop by activating the spleen tyrosine kinase-nuclear factor of activated T cells (Syk-NFAT) pathway. Finally, we observed a correlation between higher ANGPTL2 expression in primary unresectable tumors from colorectal cancer patients who underwent chemotherapy with a lower objective response rate. These findings suggest that attenuating ANGPTL2 signaling in tumor cells may block tumor cell resistance to antineoplastic therapies.

Prolyl-4-hydroxylase domain 3 (PHD3) is a critical terminator for cell survival of macrophages under stress conditions.

On a molecular level, cells sense changes in oxygen availability through the PHDs, which regulate the protein stability of the α-subunit of the transcription factor HIF. Especially, PHD3 has been additionally associated with apoptotic cell death. We hypothesized that PHD3 plays a role in cell-fate decisions in macrophages. Therefore, myeloid-specific PHD3(-/-) mice were created and analyzed. PHD3(-/-) BMDM showed no altered HIF-1α or HIF-2α stabilization or increased HIF target gene expression in normoxia or hypoxia. Macrophage M1 and M2 polarization was unchanged likewise. Compared with macrophages from WT littermates, PHD3(-/-) BMDM exhibited a significant reduction in TUNEL-positive cells after serum withdrawal or treatment with stauro and SNAP. Under the same conditions, PHD3(-/-) BMDM also showed less Annexin V staining, which is representative for membrane disruption, and indicated a reduced early apoptosis. In an unbiased transcriptome screen, we found that Angptl2 expression was reduced in PHD3(-/-) BMDM under stress conditions. Addition of rAngptl2 rescued the antiapoptotic phenotype, demonstrating that it is involved in the PHD3-mediated response toward apoptotic stimuli in macrophages.

Serum ANGPTL2 levels reflect clinical features of breast cancer patients: implications for the pathogenesis of breast cancer metastasis.

INTRODUCTION: Breast cancer is a leading cause of cancer-related death in women worldwide, and its metastasis is a major cause of disease mortality. Therefore, identification of the mechanisms underlying breast cancer metastasis is crucial for the development of therapeutic and diagnostic strategies. Our recent study of immunodeficient female mice transplanted with MDA-MB231 breast cancer cells demonstrated that tumor cell-derived angiopoietin-like protein 2 (ANGPTL2) accelerates metastasis through both increasing tumor cell migration in an autocrine/paracrine manner, and enhancing tumor angiogenesis. To determine whether ANGPTL2 contributes to its clinical pathogenesis, we asked whether serum ANGPTL2 levels reflect the clinical features of breast cancer progression. METHODS: We monitored the levels of secreted ANGPTL2 in supernatants of cultured proliferating MDA-MB231 cells. We also determined whether the circulating ANGPTL2 levels were positively correlated with cancer progression in an in vivo breast cancer xenograft model using MDA-MB231 cells. Finally, we investigated whether serum ANGPTL2 levels were associated with clinical features in breast cancer patients. RESULTS: Both in vitro and in vivo experiments showed that the levels of ANGPTL2 secreted from breast cancer cells increased with cell proliferation and cancer progression. Serum ANGPTL2 levels in patients with metastatic breast cancer were significantly higher than those in healthy subjects or in patients with ductal carcinoma in situ or non-metastatic invasive ductal carcinoma. Serum ANGPTL2 levels in patients negative for estrogen receptors and progesterone receptors, particularly triple-negative cases, reflected histological grades. CONCLUSIONS: These findings suggest that serum ANGPTL2 levels in breast cancer patients could represent a potential marker of breast cancer metastasis.

Angiopoietin-like protein 2 induced by mechanical stress accelerates degeneration and hypertrophy of the ligamentum flavum in lumbar spinal canal stenosis.

Chronic inflammation and subsequent fibrosis induced by mechanical stress play an important role in ligamentum flavum (LF) hypertrophy and degeneration in patients with lumbar spinal canal stenosis (LSCS). Angiopoietin-like protein 2 (Angptl2) is a chronic inflammatory mediator induced under various pathological conditions and increases the expression of TGF-ß1, which is a well-characterized mediator in LF hypertrophy. We investigated whether Angptl2 is induced by mechanical stress, and whether it contributes to LF hypertrophy and degeneration by activating the TGF-ß1 signaling cascade. In this study, we investigated human LF tissue and LF fibroblasts isolated from patients who underwent lumbar surgery. We found that Angptl2 was abundantly expressed in fibroblasts of hypertrophied LF tissues at both the mRNA and protein levels. This expression was not only positively correlated with LF thickness and degeneration but also positively correlated with lumbar segmental motion. Our in vitro experiments with fibroblasts from hypertrophied LF tissue revealed that mechanical stretching stress increases the expression and secretion of Angptl2 via activation of calcineurin/NFAT pathways. In hypertrophied LF tissue, expression of TGF-ß1 mRNA was also increased and TGF-ß1/Smad signaling was activated. Angptl2 expression in LF tissue was positively correlated with the expression of TGF-ß1 mRNA, suggesting cooperation between Angptl2 and TGF-ß1 in the pathogenesis of LF hypertrophy. In vitro experiments revealed that Angptl2 increased levels of TGF-ß1 and its receptors, and also activated TGF-ß1/Smad signaling. Mechanical stretching stress increased TGF-ß1 mRNA expression, which was partially attenuated by treatment with a calcineurin/NFAT inhibitor or Angptl2 siRNA, indicating that induction of TGF-ß1 expression by mechanical stretching stress is partially mediated by Angptl2. We conclude that expression of Angptl2 induced by mechanical stress in LF fibroblasts promotes LF tissue degeneration by activation of TGF-ß1/Smad signaling, which results in LF hypertrophy in patients with LSCS.

The secreted protein ANGPTL2 promotes metastasis of osteosarcoma cells through integrin α5ß1, p38 MAPK, and matrix metalloproteinases.

The tumor microenvironment can enhance the invasive capacity of tumor cells. We showed that expression of angiopoietin-like protein 2 (ANGPTL2) in osteosarcoma (OS) cell lines increased and the methylation of its promoter decreased with time when grown as xenografts in mice compared with culture. Compared with cells grown in normal culture conditions, the expression of genes encoding DNA demethylation-related enzymes increased in tumor cells implanted into mice or grown in hypoxic, serum-starved culture conditions. ANGPTL2 expression in OS cell lines correlated with increased tumor metastasis and decreased animal survival by promoting tumor cell intravasation mediated by the integrin α5ß1, p38 mitogen-activated protein kinase, and matrix metalloproteinases. The tolloid-like 1 (TLL1) protease cleaved ANGPTL2 into fragments in vitro that did not enhance tumor progression when overexpressed in xenografts. Expression of TLL1 was weak in OS patient tumors, suggesting that ANGPTL2 may not be efficiently cleaved upon secretion from OS cells. These findings demonstrate that preventing ANGPTL2 signaling stimulated by the tumor microenvironment could inhibit tumor cell migration and metastasis.

Angiopoietin-like protein 2 accelerates carcinogenesis by activating chronic inflammation and oxidative stress.

UNLABELLED: Chronic inflammation has received much attention as a risk factor for carcinogenesis. We recently reported that Angiopoietin-like protein 2 (Angptl2) facilitates inflammatory carcinogenesis and metastasis in a chemically induced squamous cell carcinoma (SCC) of the skin mouse model. In particular, we demonstrated that Angptl2-induced inflammation enhanced susceptibility of skin tissues to "preneoplastic change" and "malignant conversion" in SCC development; however, mechanisms underlying this activity remain unclear. Using this model, we now report that transgenic mice overexpressing Angptl2 in skin epithelial cells (K14-Angptl2 Tg mice) show enhanced oxidative stress in these tissues. Conversely, in the context of this model, Angptl2 knockout (KO) mice show significantly decreased oxidative stress in skin tissue as well as a lower incidence of SCC compared with wild-type mice. In the chemically induced SCC model, treatment of K14-Angptl2 Tg mice with the antioxidant N-acetyl cysteine (NAC) significantly reduced oxidative stress in skin tissue and the frequency of SCC development. Interestingly, K14-Angptl2 Tg mice in the model also showed significantly decreased expression of mRNA encoding the DNA mismatch repair enzyme Msh2 compared with wild-type mice and increased methylation of the Msh2 promoter in skin tissues. Msh2 expression in skin tissues of Tg mice was significantly increased by NAC treatment, as was Msh2 promoter demethylation. Overall, this study strongly suggests that the inflammatory mediator Angptl2 accelerates chemically induced carcinogenesis through increased oxidative stress and decreased Msh2 expression in skin tissue. IMPLICATIONS: Angptl2-induced inflammation increases susceptibility to microenvironmental changes, allowing increased oxidative stress and decreased Msh2 expression; therefore, Angptl2 might be a target to develop new strategies to antagonize these activities in premalignant tissue.

Tumor cell-derived angiopoietin-like protein ANGPTL2 is a critical driver of metastasis.

Strategies to inhibit metastasis have been mainly unsuccessful in part due to insufficient mechanistic understanding. Here, we report evidence of critical role for the angiopoietin-like protein 2 (ANGPTL2) in metastatic progression. In mice, Angptl2 has been implicated in inflammatory carcinogenesis but it has not been studied in human tumors. In patients with lung cancer, elevated levels of ANGPTL2 expression in tumor cells within the primary tumor were associated with a reduction in the period of disease-free survival after surgical resection. Transcription factors NFATc, ATF2, and c-Jun upregulated in aggressive tumor cells promoted increased Angptl2 expression. Most notably, tumor cell-derived ANGPTL2 increased in vitro motility and invasion in an autocrine/paracrine manner, conferring an aggressive metastatic tumor phenotype. In xenograft mouse models, tumor cell-derived ANGPTL2 accelerated metastasis and shortened survival whereas attenuating ANGPTL2 expression in tumor cells-blunted metastasis and extended survival. Overall, our findings showed that tumor cell-derived ANGPTL2 drives metastasis and provided an initial proof of concept for blockade of its action as a strategy to antagonize the metastatic process.

Angiopoietin-like protein 2 is an important facilitator of inflammatory carcinogenesis and metastasis.

Chronic inflammation plays important roles at different stages of cancer development, including carcinogenesis, tumor invasion, and metastasis, but molecular mechanisms linking inflammation to cancer development have not been fully clarified. Here, we report that expression of angiopoietin-like protein 2 (Angptl2), recently identified as a chronic inflammation mediator, is highly correlated with the frequency of carcinogenesis in a chemically induced skin squamous cell carcinoma (SCC) mouse model. Furthermore, Angptl2 expression in SCC is highly correlated with the frequency of tumor cell metastasis to distant secondary organs and lymph nodes. When SCC was induced in transgenic mice expressing Angptl2 in skin epithelial cells, epithelial-to-mesenchymal transitions in SCC as well as tumor angiogenesis and lymphangiogenesis were significantly increased, resulting in increased tumor cell metastasis and shortened survival compared with wild-type mice. Conversely, in a chemically induced SCC mouse model, carcinogenesis and metastasis were markedly attenuated in Angptl2 knockout mice, resulting in extended survival compared with wild-type mice. Overall, we propose that Angptl2 contributes to increased carcinogenesis and metastasis and represents a novel target to antagonize these pathologies.