Exploring pathogenic pathways in carpal tunnel syndrome: sterile inflammation and oxidative stress.

OBJECTIVES: The main objective of the current study was to find the association between oxidative stress, inflammatory markers, and electrophysiological profile with symptom severity in patients of carpal tunnel syndrome (CTS). METHODS: Thirty-two carpal tunnel syndrome patients and 32 controls were included in the study. Boston CTS questionnaire along with plasma oxidative stress markers including superoxide dismutase, malondialdehyde, and nitric oxide and inflammatory markers including IL-6 and TNF-α were compared with the electrophysiological parameters derived from nerve conduction studies. Statistical significance of the levels between groups was calculated using unpaired-t test after checking for normality with D'Agostino & Pearson omnibus normality test. RESULTS: We found that the median nerve conduction velocity was prolonged, amplitude was decreased, while the levels of oxidative stress markers like malondialdehyde (MDA), superoxidase dismutase (SOD), and nitric oxide (NO) were increased in CTS patients compared to controls. Inflammatory markers like interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) were also increased in CTS patients. We found that plasma SOD and TNF-α correlated well with the median motor amplitude. There was no other significant correlation between oxidative stress markers and inflammatory markers with nerve conduction studies or disease severity. Patients with mild disease also showed lesser levels of SOD, NO, IL-6, and TNF-α markers than patients with severe disease. CONCLUSIONS: CTS is probably a disease of sterile inflammation and disbalance of oxidative stress, with higher inflammatory and oxidative stress markers pointing to a more severe disease.

Cardiac Amyloidosis Screening at Trigger Finger Release Surgery.

Cardiac amyloidosis is often preceded by orthopedic manifestations such as carpal tunnel syndrome, and 10% of patients who underwent idiopathic carpal tunnel release surgery will have biopsy-confirmed amyloid deposits in the tenosynovial sheath. Trigger finger is also commonly reported in patients with amyloidosis and involves the same tendon sheath as carpal tunnel syndrome, but the prevalence of amyloid deposition is unclear. This prospective cross-sectional study enrolled 100 patients aged ≥50 years at the time of surgery for idiopathic trigger finger. Patients underwent release surgery, and a sample of the tenosynovium of the affected finger was excised, stained with Congo red, and subtyped with mass spectrometry if amyloid was demonstrated. Further cardiac evaluation was performed in patients with amyloid deposition. Of the 100 patients (mean age 65.5 ± 8.1 years) enrolled, only 2 demonstrated amyloid deposits on Congo red staining. One patient with previous proteinuric kidney disease had fibrinogen A α-chain amyloidosis, and the other patient had untyped amyloidosis. Neither patient had cardiac involvement. A total of 13 of the 100 patients underwent concomitant carpal tunnel release surgery, and 2 of these patients had amyloid deposits in the carpal tunnel with "false-negative" samples from the trigger finger tenosynovium. In conclusion, biopsy during trigger finger release surgery demonstrated a 2% yield for amyloidosis, which is significantly lower than the previously published yield of 10% during carpal tunnel release surgery. This observation has important implications for the development of diagnostic algorithms to screen patients for amyloidosis during orthopedic operations.

Systemic Amyloidosis Caused by Monoclonal Immunoglobulins: Soft Tissue and Vascular Involvement.

Clinical features of soft tissue amyloid light-chain (AL) amyloidosis include macroglossia, arthropathy, muscle pseudohypertrophy, skin plaques, and carpal tunnel syndrome. Vascular manifestations of AL amyloid include periorbital ecchymosis, jaw or limb claudication, and even myocardial infarction caused by occlusion of small vessel coronary arteries. Some of these features, such as macroglossia, periorbital ecchymosis, and the so-called shoulder-pad sign, are pathognomonic for AL amyloidosis. These findings may be the initial presenting features of the disease, and the recognition of these red flag symptoms is very important for the diagnosis and early intervention on the underlying plasma cell disease.

Mutations in COMP cause familial carpal tunnel syndrome.

Carpal tunnel syndrome (CTS) is the most common peripheral nerve entrapment syndrome, affecting a large proportion of the general population. Genetic susceptibility has been implicated in CTS, but the causative genes remain elusive. Here, we report the identification of two mutations in cartilage oligomeric matrix protein (COMP) that segregate with CTS in two large families with or without multiple epiphyseal dysplasia (MED). Both mutations impair the secretion of COMP by tenocytes, but the mutation associated with MED also perturbs its secretion in chondrocytes. Further functional characterization of the CTS-specific mutation reveals similar histological and molecular changes of tendons/ligaments in patients' biopsies and the mouse models. The mutant COMP fails to oligomerize properly and is trapped in the ER, resulting in ER stress-induced unfolded protein response and cell death, leading to inflammation, progressive fibrosis and cell composition change in tendons/ligaments. The extracellular matrix (ECM) organization is also altered. Our studies uncover a previously unrecognized mechanism in CTS pathogenesis.

Interleukin-6 secretion by fibroblasts in carpal tunnel syndrome patients is associated with trigger finger and inhibited by tranilast.

INTRODUCTION: In this study we aimed to clarify the association between interleukin-6 (IL-6) secretion in fibroblasts in carpal tunnel syndrome (CTS) patients and their biophysical parameters, including association with trigger finger and whether tranilast inhibits IL-6 secretion in fibroblasts. METHODS: Fibroblasts were obtained from tenosynovial tissue harvested from idiopathic CTS patients undergoing carpal tunnel release and tenosynovectomy and cultured in media containing tranilast with or without tumor necrosis-α (TNF-α) or interleukin-1ß (IL-1ß). Their proliferation was evaluated and secreted IL-6 levels and IL-6 mRNA expression were quantified. Correlations between IL-6 concentration and patient characteristics were examined. RESULTS: IL-6 secretion was significantly associated with trigger finger (P = .001). Tranilast inhibited fibroblast proliferation in a dose-dependent manner and suppressed IL-6 secretion. DISCUSSION: IL-6 overproduction in tenosynovial tissue may account for the association between CTS and trigger finger. Future studies should investigate whether tranilast can be used to treat patients with CTS.

Tenosynovial and Cardiac Amyloidosis in Patients Undergoing Carpal Tunnel Release.

BACKGROUND: Patients with cardiac amyloidosis often have carpal tunnel syndrome that precedes cardiac manifestations by several years. However, the prevalence of cardiac involvement at the time of carpal tunnel surgery has not been established. OBJECTIVES: The authors sought to identify the prevalence and type of amyloid deposits in patients undergoing carpal tunnel surgery and evaluate for cardiac involvement. The authors also sought to determine if patients with soft tissue transthyretin (TTR) amyloid had abnormal TTR tetramer kinetic stability. METHODS: This was a prospective, cross-sectional, multidisciplinary study of consecutive men age ≥50 years and women ≥60 years undergoing carpal tunnel release surgery. Biopsy specimens of tenosynovial tissue were obtained and stained with Congo red; those with confirmed amyloid deposits were typed with mass spectrometry and further evaluated for cardiac involvement with biomarkers, electrocardiography, echocardiography with longitudinal strain, and technetium pyrophosphate scintigraphy. Additionally, serum TTR concentration and tetramer kinetic stability were examined. RESULTS: Of 98 patients enrolled (median age 68 years, 51% male), 10 (10.2%) had a positive biopsy for amyloid (7 ATTR, 2 light chain [AL], 1 untyped). Two patients were diagnosed with hereditary ATTR (Leu58His and Ala81Thr), 2 were found to have cardiac involvement (1 AL, 1 ATTR wild-type), and 3 were initiated on therapy. In those patients who had biopsy-diagnosed ATTR, there was no difference in plasma TTR concentration or tetramer kinetic stability. CONCLUSIONS: In a cohort of patients undergoing carpal tunnel release surgery, Congo red staining of tenosynovial tissue detected amyloid deposits in 10.2% of patients. Concomitant cardiac evaluation identified patients with involvement of the myocardium, allowing for implementation of disease-modifying therapy. (Carpal Tunnel Syndrome and Amyloid Cardiomyopathy; NCT02792790).

Expression of vitamin D receptor in the subsynovial connective tissue in women with carpal tunnel syndrome.

Studies suggest that low vitamin D levels are associated with carpal tunnel syndrome. We aimed to evaluate whether level of vitamin D receptor expression in the endothelial cells of the subsynovial connective tissue is associated with clinical features of carpal tunnel syndrome. We obtained the subsynovial connective tissue from 52 women with carpal tunnel syndrome during surgery and performed immunohistochemical analysis of vitamin D receptors in the endothelial cells of the subsynovial connective tissue. We explored correlation of vitamin D receptor expression with clinical features of carpal tunnel syndrome, such as age, symptom duration, symptom severity and electrophysiological severity. Diverse range of vitamin D receptor expression was observed. Vitamin D receptor expression was independently associated with distal motor latency. This suggests that vitamin D receptor expression may be associated with disease progression, as prolonged distal motor latency reflects severity of the disease. Further studies are necessary to explore the role of vitamin D and vitamin D receptors in patients with carpal tunnel syndrome. LEVEL OF EVIDENCE: IV.

PDGFR Signaling Mediates Hyperproliferation and Fibrotic Responses of Subsynovial Connective Tissue Cells in Idiopathic Carpal Tunnel Syndrome.

Fibrosis of the subsynovial connective tissue (SSCT) is a pathognomonic change in carpal tunnel syndrome (CTS). Identification of molecular targets and anti-fibrotic therapies could provide new treatment strategies for CTS. The contribution of SSCT cells to fibrosis and the signaling pathways that initiate and aggravate fibrosis in CTS remain unknown. Here we report that platelet-derived growth factor receptor alpha (PDGFRα) positive ( + ) cells accumulate in CTS SSCT and that the presence of fibrotic growth factor, PDGF-AA, results in increased proliferation of PDGFRα+ cells via PI3K/Akt signaling pathway. Although PI3K inhibition decreased proliferation, there was no change in fibrosis-related gene expression. Indeed, protein levels of fibrosis signaling mediator TGF-ß remained the same and the second messenger, Smad2/3, accumulated in the nucleus. In contrast AMP-activated protein kinase (AMPK) activation, which can be induced with metformin and AICAR inhibited proliferation, TGF-ß expression, and altered cell morphology in SSCT cells. Further we show that AMPK activation by metformin reduced collagen III levels and the ratio of Collagen I to Collagen III. Both AICAR and metformin reduced F-actin and significantly reduced the fiber cross alignment. Our results suggest that PDGFRa signaling may be an important fibrosis target and that activators of AMPK, may be an important therapeutic approach for treating CTS.

Establishing and validating the fluorescent amyloid ligand h-FTAA (heptamer formyl thiophene acetic acid) to identify transthyretin amyloid deposits in carpal tunnel syndrome.

Transthyretin-derived (ATTR) amyloidosis is a frequent finding in carpal tunnel syndrome. We tested the following hypotheses: the novel fluorescent amyloid ligand heptameric formic thiophene acetic acid (h-FTAA) has a superior sensitivity for the detection of amyloid compared with Congo red-staining; Amyloid load correlates with patient gender and/or patient age. We retrieved 208 resection specimens obtained from 184 patients with ATTR amyloid in the carpal tunnel. Serial sections were stained with Congo red, h-FTAA and an antibody directed against transthyretin (TTR). Stained sections were digitalized and forwarded to computational analyses. The amount of amyloid was correlated with patient demographics. Amyloid stained intensely with h-FTAA and an anti-TTR-antibody. Congo red-staining combined with fluorescence microscopy was significantly less sensitive than h-FTAA-fluorescence and TTR-immunostaining: the highest percentage area was found in TTR-immunostained sections, followed by h-FTAA and Congo red. The Pearson correlation coefficient was .8 (Congo red vs. h-FTAA) and .9 (TTR vs. h-FTAA). Amyloid load correlated with patient gender, anatomical site and patient age. h-FTAA is a highly sensitive method to detect even small amounts of ATTR amyloid in the carpal tunnel. The staining protocol is easy and h-FTAA may be a much more sensitive procedure to detect amyloid at an earlier stage.

Amyloid detection in the transverse carpal ligament of patients with hereditary ATTR V30M amyloidosis and carpal tunnel syndrome.

INTRODUCTION: Carpal tunnel syndrome (CTS) is a nonspecific manifestation of hereditary ATTR amyloidosis (ATTRm). Amyloid deposition of wild-type TTR (WT-ATTR) has been found in transverse carpal ligament (TCL) in idiopathic CTS. We retrospectively studied a group of patients with ATTRm and CTS submitted to carpal tunnel release surgery (CTRS). METHODS: From the nerve conduction studies performed in our Clinical Unit dedicated to hereditary amyloidosis between July 2009 and October 2013, we selected patients who fulfilled neurophysiological criteria for CTS, had been submitted to CTRS and whose TCL was available for pathology. Clinical registries were reviewed and amyloid detection in the ligaments was performed using Congo-red staining. RESULTS: We included 16 patients: three males (18.8%), mean age = 46.1 years old, all with V30M mutation. At the time of surgery, four patients were considered asymptomatic and 12 symptomatic carriers, five of them late-onset ATTRm (onset age >50 years old). In all but one patient, the CTS preceded the polyneuropathy. Amyloid detection in the TCL was positive in 14 patients (87.5%). DISCUSSION/CONCLUSIONS: In most patients, CTS preceded or was contemporary to the polyneuropathy and amyloid detection in TCL was positive. The detection of amyloid in TCL may add specificity to CTS as an early manifestation of the disease but more studies are needed.

Relaxin Modulates the Expression of MMPs and TIMPs in Fibroblasts of Patients with Carpal Tunnel Syndrome.

PURPOSE: The aim of this study was to investigate the anti-fibrotic effect of relaxin in subsynovial fibroblasts activated by transforming growth factor beta (TGF-ß). MATERIALS AND METHODS: To test the anti-fibrotic effect of an adenovirus-relaxin construct (Ad-RLN) on subsynovial fibroblasts in vitro, cells from subsynovial connective tissue of patients with carpal tunnel syndrome were activated with TGF-ß1 and exposed to Ad-RLN (as a therapeutic gene) or adenovirus-lacZ construct (as a marker gene) for four hours. Subsynovial fibroblast cultures without adenoviral exposure served as controls. RESULTS: We observed induction of gene expressions of collagen I, III and IV, as well as the abatement of alpha-smooth muscle actin (a-SMA) synthesis, Smad2 phosphorylation, and fibronectin at the protein level, in comparison to controls. In addition, protein expressions of matrix metalloproteinase (MMP) I was significantly induced, whereas the protein expressions of tissue inhibitor of metalloproteinases (TIMP) I and IV were reduced due to relaxin expression. CONCLUSION: RLN prevents excessive synthesis of extracellular matrix by reducing the expressions of its components, such as fibronectin, a-SMA, and phosphorylated Smad2, by increasing the expression of MMPs; and by decreasing the expression of TIMPs.

Carpal tunnel syndrome: a common initial symptom of systemic wild-type ATTR (ATTRwt) amyloidosis.

BACKGROUND: Systemic wild-type ATTR (ATTRwt) amyloidosis is a prevalent aging-related disorder. However, a limited number of systemic ATTRwt amyloidosis patients have been diagnosed antemortem, and therefore, the prevalence of ATTRwt is underestimated. Here, we investigated clinical findings of a series of systemic ATTRwt amyloidosis patients with antemortem diagnosis. METHODS: Thirty-one consecutive patients diagnosed with systemic ATTRwt amyloidosis at Shinshu University Hospital were included in this study. Systemic ATTRwt amyloidosis was diagnosed based on proven ATTR amyloid deposition in biopsy specimens and confirmation of wild-type TTR genotype. RESULTS: The systemic ATTRwt amyloidosis patients consisted of 24 men and seven women, and mean age of onset was 69.8 ± 9.0 years. The most common initial symptom was carpal tunnel syndrome (CTS, 17 patients), followed by heart failure symptoms (14 patients). The mean age at diagnosis was 74.5 ± 8.3 years and the duration of illness from onset to diagnosis was 5.4 ± 4.4 years. Cardiogenic embolism and renal dysfunction are also frequently seen during the course of the disease. CONCLUSIONS: CTS is the most common initial symptom of systemic ATTRwt amyloidosis. Our results suggest the possibility of systemic ATTRwt amyloidosis diagnosis at an early stage by carefully examining patients with CTS.

Elevated basal cytosolic calcium of endothelial cells influences the post-surgical outcome in diabetic CTS.

Background Type 2 diabetes mellitus (T2DM)-induced neuropathy and ischemia-reperfusion post-surgery prolong carpal tunnel syndrome (CTS) pathology, but the effect of T2DM on the prognostic outcome of carpal tunnel (CT) release surgery needs to be investigated. Materials and methods A total of 64 individuals with CTS underwent CT release surgery. HbA1c levels identified their diabetic status. The individual prognostic outcomes were measured by nerve conduction velocity (NCV), amplitude, and latency. Measurement of [Ca2+]c and reactive oxygen species (ROS) from isolated endothelial cells (ECs) revealed the oxidative burden of the normal and diabetic CTS phenotypes. Results CTS individuals with HbA1c > 7 showed decreased NCV (≈22 m/s) and amplitude (≈4.2 mV) with increased latency (≈6 ms), compared to groups with HbA1c ≤ 7. Further to CT release surgery, the reversal of the nerve conduction to normalcy was greatly influenced by the diabetic profile of the individuals. Our results showed elevated basal [Ca2+]c and corresponding high cytosolic ROS in the ECs isolated from individuals with HbA1c > 7 compared to the diabetic and healthy control groups. Conclusion The individuals with diabetic index showed suboptimal neuronal performance pre- and post-CT release surgery. Oxidative stress mediated by high [Ca2+]c and ROS of ECs dissipates to adjoining cells worsening the pathology of the untreated CTS.

Enhanced expression of Wnt9a in the flexor tenosynovium in idiopathic carpal tunnel syndrome.

This study aimed to clarify the association between abnormal Wnt signaling and the cause of idiopathic carpal tunnel syndrome (ICTS) and whether an association exists between Wnt signaling and cell proliferation in the flexor tenosynovium. The subjects included nine patients with ICTS; the controls were nine patients with distal radius fractures without any symptoms of carpal tunnel syndrome. We extracted mRNA from the flexor tenosynovium and compared the expression levels of genes encoding 17 types of Wnt in both subjects and controls via quantitative real-time polymerase chain reaction (PCR). Expression levels of factors involved in cell proliferation, such as estrogen-responsive finger protein, epidermal growth factor receptor, heparin binding-epidermal growth factor-like growth factor, insulin-like growth factor-1, and vascular endothelial growth factor (VEGF) were also measured using quantitative real-time PCR. In addition, we compared the Wnt and MIB-1 protein expression levels to clarify the effect of Wnt on cell proliferation. Quantitative real-time PCR revealed significantly greater expression of the gene encoding Wnt9a in subjects with ICTS than in controls and also revealed a positive correlation between the expression of genes encoding Wnt9a and VEGF in subjects with ICTS. Quantitative evaluation using immunohistochemical staining also indicated more marked Wnt9a expression in subjects than in controls. However, there was no relationship between the expression of Wnt9a and the cell proliferation index MIB-1. These results indicate that Wnt9a expression is enhanced in ICTS and that Wnt9a may be involved in VEGF expression in ICTS.

Collagen gel contraction as a measure of fibroblast function in carpal tunnel syndrome.

Noninflammatory subsynovial connective tissue (SSCT) fibrosis with nerve compression is a prominent feature of carpal tunnel syndrome (CTS). Studies have shown that SSCT matrix synthesis and material property changes in CTS are associated with increased activity of transforming growth factor (TGF)-ß1. The aim of this study were to (1) investigate the ability of SSCT fibroblasts from CTS patients and unaffected individuals to contract a collagen gel ring and (2) determine how the addition of TGF-ß1 affects this ability. SSCT fibroblasts from three normal cadavers and three age-matched female patients who had undergone surgery for CTS were used. Results showed patient cell-seeded gels had a significantly higher contraction rate (p < 0.001) than control cells, and fully contracted gel rings possessed a significantly higher tensile strength (p = 0.003) and stiffness (p < 0.001). Furthermore, TGF-ß1 significantly intensified contraction rate (p < 0.001), tensile strength (p < 0.001), and stiffness (p < 0.001). In conclusion, SSCT cells from normal donors and CTS patients contract collagen gel rings differently, and this ability is affected by TGF-ß1 treatment. This cell-seeded collagen gel model may be useful for developing new methods of stopping or eliminating the effect of TGF-ß1 on the SSCT fibroblasts and surrounding matrix, which might aid in the identification of medical treatment for CTS.

TGF-ß signaling regulates fibrotic expression and activity in carpal tunnel syndrome.

Fibrosis of the subsynovial connective tissue (SSCT) is a predominant feature of carpal tunnel syndrome (CTS). While the nature of CTS has been extensively studied, little is known about the etiology of this disease. We investigated SSCT tissue from patients with CTS and control subjects using fibrosis arrays and cell culture analysis. Twofold changes in fibrotic gene expression were found in multiple genes from patient SSCT using fibrosis arrays. This data was confirmed via qRT-PCR on a subset of genes; collagen I (Col1), collagen III (Col3), connective tissue growth factor (CTGF), transforming growth factor ß (TGF-ß), and SMAD3 (P < 0.05) which significantly corroborate the fold changes found in the fibrosis arrays. To further explore the nature of SSCT fibrosis, cells were isolated from patient and control tissue. Col1, Col3, TGF-ß, and SMAD3 were highly expressed in patient SSCT fibroblasts as compared to control (P < 0.05). Further, fibrotic genes expression was decreased by inhibiting TGF-ß receptor I (TßRI) activity (P < 0.05). TGF-ß second messenger SMAD activity was significantly activated in SSCT fibroblasts from patients and this activation was abrogated by inhibiting TßRI signaling (P < 0.05). These findings suggest that blocking TGF-ß signaling may be an important therapeutic approach to treating the underlying fibrosis of SSCT in CTS patients.

Carpal tunnel syndrome is associated with high fibrinogen and fibrinogen deposits.

BACKGROUND: Idiopathic carpal tunnel syndrome (ICTS) is a common entrapment neuropathy. Some cases of ICTS are linked to mutations of the transthyretin gene, whereas others are associated with systemic amyloidosis. The majority of ICTS cases are of unknown etiology. OBJECTIVE: To study molecular mechanisms of ICTS development. METHODS: A total of 71 ICTS patients and 68 control subjects were included in the study. The fibrinogen level was determined before surgery and its deposition in the transversal carpal ligament (TCL) was detected by immunohistochemistry, Western blot, and mass spectrometry. Fibrinogen interaction with other proteins was studied by immunoprecipitation assay. RESULTS: Plasma levels of the proinflammatory and hemostatic protein fibrinogen are elevated in ICTS patients. Other measured systemic inflammatory markers were not affected, and local inflammatory responses in TCL were absent. ICTS patients have shorter bleeding times, probably because of the elevated plasma levels of fibrinogen. Polymorphisms of the fibrinogen B promoter region were previously associated with increased plasma fibrinogen, but this association was not observed among patients with ICTS. Interestingly, we detected fibrinogen deposits in the TCL, whereas transcriptional activity of the fibrinogen genes was low. Amyloidogenic proteins, including transthyretin and α-synuclein, were also found in the TCL, whereas their local transcriptional activity was rather high. Finally, we demonstrated that fibrinogen interacts with transthyretin and α-synuclein in TCL lysates. CONCLUSION: Our data indicate that fibrinogen and other aggregation-prone proteins have potentially important roles in the pathogenesis of ICTS.

Molecular and pathological studies in the posterior interosseous nerve of diabetic and non-diabetic patients with carpal tunnel syndrome.

AIMS/HYPOTHESIS: We sought to establish the molecular and pathological changes predisposing diabetic and non-diabetic patients to the development of carpal tunnel syndrome (CTS). METHODS: The posterior interosseous nerve (PIN) was biopsied in 25 diabetic and 19 non-diabetic patients undergoing carpal tunnel decompression for CTS. Detailed morphometric and immunohistological analyses were performed in the nerve biopsy. RESULTS: In diabetic patients median nerve distal motor latency was prolonged (p < 0.05 vs non-diabetic patients), PIN myelinated fibre density (p < 0.05), fibre area (p < 0.0001) and axon area (p < 0.0001) were reduced, the percentage of unassociated Schwann cell profiles (p < 0.0001) and unmyelinated axon density (p < 0.0001) were increased and the axon diameter was reduced (p < 0.0001). Endoneurial capillary basement membrane area was increased (p < 0.0001) in diabetic patients, but endothelial cell number was increased (p < 0.01) and luminal area was reduced (p < 0.05) in non-diabetic patients with CTS. There was no difference in the expression of hypoxia-inducible factor 1α between diabetic and non-diabetic patients with CTS. However, the expression of vascular endothelial growth factor A (VEGF) (p < 0.05) and its receptors VEGFR-1 (p < 0.01) and VEGFR-2 (p < 0.05) was significantly increased in diabetic patients, particularly those with type 1 diabetes, and related to the severity of nerve fibre pathology. CONCLUSIONS/INTERPRETATION: This study demonstrates increased nerve fibre and microvascular pathology in relation to enhanced expression of VEGF and its receptors in a non-compressed nerve in diabetic compared with non-diabetic patients with CTS. It therefore provides a potential molecular and pathological basis for the predisposition of diabetic patients to the development of CTS.

Response of dupuytren fibroblasts to different oxygen environments.

PURPOSE: It is thought that local ischemia and oxygen radicals are responsible for fibroblast-to-myofibroblast cell transformation and proliferation. We hypothesized that hypoxia could differentially activate the contractility of fibroblasts from normal human palmar fascia and from fibroblasts-myofibroblasts of Dupuytren cords. METHODS: Normal palmar fascia from 5 patients with carpal tunnel syndrome and Dupuytren cords from 5 patients were harvested. Cells were cultured from all tissue samples, and collagen lattices were prepared containing these cells. Oxygen treatment subgroups were created and incubated under hypoxic (1% O(2), 5% CO(2), and 94% N(2)), normoxic (21% O(2), 5% CO(2), and 74% N(2)), and hyperoxic (100% oxygen using 2.4 atm pressure twice a day for 7 d) conditions. After 7 days, each subgroup was photographed, and lattices were released from dishes. Postrelease photographs were taken immediately, 5 minutes after release, and after 1 hour. Areas of the lattices at each time point were calculated using MetaMorph software. Actin staining and live/dead cell analysis was performed. Linear repeated measures analysis of variance was used for data analysis given that contraction levels were measured over 3 distinct time points. RESULTS: We found a statistically significant difference between normal samples and Dupuytren samples in mean contraction levels over time. There was no statistically significant difference between tissue groups over the 3 time periods based on the oxygen treatment received. CONCLUSIONS: Our results showed a greater degree of contractility in Dupuytren disease cells than normal fibroblasts. However, the contraction in either group was not affected by oxygen level. Future in vivo research is needed to better understand the nature of pathophysiology of Dupuytren disease.

ATTR amyloid in the carpal tunnel ligament is frequently of wildtype transthyretin origin.

The carpal tunnel ligament often encloses transthyretin-derived (ATTR) amyloid deposits. In this study we tested the hypothesis that ATTR amyloid in the carpal tunnel ligament is most commonly of wildtype origin in a Caucasian population without endemic background of familial amyloid polyneuropathy. All resection specimens from the carpal tunnel ligament were retrieved from the Amyloid Registry of the University of Kiel spanning the period of 2004-2011 and dichotomized into two study groups: the first study group of 25 patients was obtained from diverse referring pathologists. The second group comprised a patient cohort of 73 patients obtained from a single-referring department of pathology. The selection of biopsies was based on the histological identification of amyloid by Congo red staining and polarization microscopy between crossed polars and immunohistochemical classification as ATTR amyloid. A novel anti-TTR-peptide antibody was raised in rabbits using a recombinant peptide (FHEHAEVVFTANDSGPRRYT) spanning residues 87-106 of the TTR protein. Amplification of the TTR exons 1, 2, 3 and 4 was done by a nested polymerase chain reaction approach. Ninety-eight biopsies were available from 98 patients, including 51 women and 47 men. All amyloid deposits showed strong immunoreactions with the novel anti-TTR peptide antibody. In 81 of 98 patients, genomic DNA was available. In 10 (12%) patients non-amyloidogenic TTR gene mutations were found with the following amino acid substitutions: p.G6S (normal allelic variant). A single patient carried a p.G6S and a p.M13I-variant. The remaining patients all showed wildtype sequence of the TTR gene (70 patients). No significant difference was found between the two study groups. ATTR amyloid in the carpal tunnel ligament is commonly of wildtype origin and genetic counseling is not mandatory in these patients.