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IntroductionThe pathogenetic mechanism of low back pain and nerve root damage in lumbar disc herniation is the subject of ongoing debate. In particular, given that the mechanicalischaemic hypothesis alone cannot explain the cause-effect relationship between disc degeneration and neurological impairment, a biochemical mechanism is likely to be involved. It has recently been demonstrated that the autologous nucleus pulposus can induce histological and functional changes in spinal nerve roots when applied epidurally [17]. Cells of the nucleus pulposus can produce prostaglandin E2, interleukin-1 and interleukin-6 (IL-6) [31], phospholipase A2 [26], and growth factors like fibroblast-like growth factor (FGF) [32] and insulin-like growth factor-1 (IGF-1) [18]. These factors are known to control cell metabolism and to promote inflammatory processes. Moreover, recent studies suggest a critical role for IL-6 and its receptor in the modulation of pain [8]. The mechanisms of action underlying the possible effect of these factors on spinal nerve root structure and function are, however, still unknown. In addition, the fact that nerve roots differ from peripheral nerves in their anatomical, biomechanical, and physiological properties prevents extrapolation from the extensive literature and the numerous experimental models of peripheral nerve compression to the pathophysiology of root injury [5,23,25]. The working hypothesis of the present study is that transforming growth factor-β1 (TGF-β1), IGF-1, IL-6 and IL-6-receptor (IL-6R) can be produced at the site of herniation. This hypothesis was immunohistochemically explored by analysing normal and protruded intervertebral disc tissue for these factors.Abstract Nerve root irritation induced by factors produced by the intervertebral disc may play a crucial role in the pathophysiology of sciatic pain production. In this study we used immunohistochemistry to investigate the presence of transforming growth factor-β1 (TGF-β1), insulinlike growth factor-1 (IGF-1), interleukin-6 (IL-6), IL-6-receptor (IL-6R) and fibronectin in lumbar disc bioptic specimens from 30 patients with disc herniation (protrusion type). Chondrocytes of herniated discs stained positive for TGF-β1, IGF-1, IL-6 and fibronectin. We demonstrated for the first time the presence of IL-6-R in the chondrocytes of herniated tissue. Specimens from autoptic healthy tissue were used as controls. In these sections no immunoreaction for TGF-β1, IL-6, or IL-6R was found, while they expressed IGF-1 and fibronectin, but in lower quantities than herniated discs. These results demonstrated the production of factors such as TGF-β1, IGF-1, IL-6, IL-6R and fibronectin at the site of lumbar disc herniation.

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Carpal tunnel syndrome (CTS) is a compression median nerve neuropathy common in women at menopausal age. The aim of this work was to study immunohistochemically the expression of estrogen (ER) and progesterone (PR) receptors in CTS and control specimens. Biopsies of transverse carpal ligament (TCL) and flexor tendon synovitis were collected from 23 women and from 7 men undergoing surgery for median nerve decompression at the wrist for CTS. In TCL and synovial tissue, cells expressed ER and PR with statistically significant differences related to the age and sex of patients. Immunoreactivity was observed in fibroblasts of TCL, and in lining cells and fibroblasts of synovial tissue. In women, the number of ER-positive cells in the TCL and synovial tissue increased with the age, peaking at 55-70 years, and then decreasing. PR-immunoreactivity was observed only in fibroblasts of TCL and its expression decreased with age, while no immunolabeling was found in the synovial tissue. In TCL samples, the number of ER- and PR-positive cells in non-CTS patients was significantly lower than in CTS patients. These results demonstrate that ER and PR are present in TCL and flexor tendon synovitis, suggesting a role for sex steroid hormones in the pathogenesis of CTS disease.

Nerve growth factor (NGF) exerts its action through two types of receptor: high-affinity tyrosine kinase A receptor (trkA) and low-affinity p75 receptor. NGF has a neurotrophic role in central and peripheral nervous system development, but there is also clear evidence of its involvement in the developing skeleton. The aim of the present immunohistochemical study was to investigate the expression and distribution of NGF, trkA, and p75 in normal cartilaginous tissues from adult subjects: articular and meniscal cartilage of the knee, cartilage from the epiglottis, and intervertebral disc tissue. Detection of NGF mRNA was also performed by in situ hybridization. Immunoreaction for NGF and the two receptors in articular chondrocytes, chondrocyte-like cells of meniscus and annulus fibrosus, and chondrocytes of the epiglottis demonstrated that they are all expressed in hyaline, fibrous and elastic cartilaginous tissues, suggesting that they could be involved in cartilage physio-pathology

To investigate the pathogenesis of the degenerative changes of the ligamentum flavum occurring in lumbar spine stenosis, yellow ligament cells from patients with lumbar spine stenosis were cultured for the first time and subjected to biochemical, histochemical and immunohistochemical study. Stenotic ligamentum flavum (SLF) cells were seen to express high levels of alkaline phosphatase (ALP) activity and to produce a matrix rich in type I and 111 collagen, fibronectin and osteonectin. The matrix mineralized only following p-glycerophosphate (PGP) and ascorbic acid supplementation. Stimulation with human parathyroid hormone (PTH) increased intracellular CAMP concentration. These findings indicate that there was significant evidence of osteobkast-like activity in these cells. SLF cells also stained for SlOO protein, type I1 and type X collagen, and co-localized type I1 collagen and ALP labelling, reflecting the presence of hypertrophic chondrocyte-like cells. Cultures from control patients showed neither osteoblastic nor chondrocytic features: they expressed type I and type I11 collagen and fibronectin, but did not stain for osteonectin, nor were bonelike calcifications observed in presence or absence of PGP. Normal ligamentum flavum (NLF) cells did not synthesized SlOO protein or type I1 or type X collagen, and showed a weaker response to PTH stimulation. Our data demonstrated the presence of hypertrophic chondrocytes with an osteoblast-like activity in the ligamentum flavum of patients with spinal stenosis suggesting that they could have a role in the pathophysiology of the heterotopic ossification of ligamentum flavum (OLF) in lumbar spine stenosis.

Palmar fascia tissue and cultured cells from patients with Dupuytren's contracture and from normal subjects were characterized and analyzed for androgen receptor expression. Androgen receptors have never been studied in Dupuytren's myofibroblasts and may have a role in its high male predominance. Surgical samples were collected from eight patients undergoing surgery for Dupuytren's contracture and from four patients with carpal tunnel syndrome, used as control tissue. Immunohistochemical analysis was performed on tissue samples and on cell cultures with anti-androgen receptor, anti-cx-smooth muscle actin, anti-fibronectin, and anti-type I and 111 collagen antibodies using the biotin-avidin peroxidase method as revelatory system. Immunostaining for androgen receptors in tissue samples and cultured cells revealed nuclear reaction in many Dupuytren's myofibroblasts, but in few fibroblasts of the normal palmar Fascia. In a double-labeling study, androgen receptors were seen to co-localize with cx-actin in both cell cultures and tissue samples.We present the first evidence that the palmar fascia is a target tissue for androgen action and that the expression of androgen receptors in Dupuytren's contracture is considerably higher than in the normal palmar fascia. Further studies will need to evaluate whether the androgen-responsive state of the tissue is related to the high incidence of Dupuytren's contracture in the male sex.

Experimental and clinical studies have shown that a vein segment filled with skeletal muscle used to bridge a peripheral nerve defect (muscle-vein-combined graft) leads to good nerve repair. However, the molecular basis of the nerve fiber regeneration process along this type of graft still remains to be elucidated. The aim of this study was to verify the expression of two neurotrophins, nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), as well as their receptors, trkA and p75, in an early stage of axonal regeneration in muscle-vein-combined grafts. Severed rat sciatic nerves were repaired by means of 1-cm-long musclevein-combined grafts and withdrawn immediately after surgery (control grafts) and 5 days after surgery. Longitudinal sections of grafts were immunostained by means of the following antibodies: anti-NGF, anti-BDNF, anti-trkA, and antip75. An anti-glial fibrillar acid protein (anti-GFAP) antibody was used to recognize Schwann cells. Results showed the presence of a number of GFAP-positive Schwann cells inside the muscle-vein grafts. Many of these cells reacted for NGF, BDNF, and p75, but not trkA. In control grafts, i.e., immediately after surgery, no immunostaining was detected for any of the antibodies used in this study. These observations suggest that, very early after surgery, the muscle-vein-combined graft offers to growing axons an environment particularly favorable for regeneration, providing us with a possible explanation for the efficacy of this grafting technique for peripheral nerve repair.