Focus on pain mechanisms and pharmacotherapy in the treatment of fibromyalgia syndrome.

OBJECTIVE: To critically evaluate the role of several notable 'pain pathways' in the fibromyalgia syndrome (FMS). METHODS: PubMed provided the data base for peer-reviewed basic and clinical science studies on musculoskele-tal and neuropathic pain mechanisms with a principal emphasis on critically appraising papers from 2002 to the present. RESULTS: FMS pharmacotherapy is more prevalent in clinical practice as our understanding of the cellular, molecular and pathophysiologic mechanisms contributing to widespread musculoskeletal and neuropathic pain has emerged. Thus, several 'pain pathways' including high-voltage activated Ca2+ channels and the K(v)1 family of K+ channels ion channels appear related to the efficacy of pregabalin and amitryptyline, respectively, in FMS. Additionally, serotonergic and serotonergic/norepinephrine receptor-mediated mechanisms may explain the reported pharmacologic efficacy in FMS of mirtazapine, duloxetine and milnacipran. By contrast, the decreased level of micro-opioid receptors in the CNS of FMS patients suggests a mechanism as to why opioid therapy should be avoided. However, increased peripheral benzodiazepine receptors on monocytes from FMS patients suggested an explanation for the reported efficacy of olanzapine in FMS. CONCLUSION: Pregabalin was the first drug approved by the FDA for the treatment of FMS-related pain. Drugs that have been assessed for their potential use in FMS pharmacotherapy include gabapentin and tricylic antidepressants. These drugs appear to target specific Ca2+ or K+ ion channels notable for their involvement in mediating neuropathic pain. Serotonin and norepinephrine reuptake inhibitors including, mirtazapine, duloxetine and milnacipran appear to be more efficacious in FMS than selective serotonin reuptake inhibitors. Milnacipran became the second FDA-approved drug for FMS.

Small molecular weight inhibitors of stress-activated and mitogen-activated protein kinases.

The stress-activated protein kinase (SAPK) and mitogen-activated protein kinase (MAPK) sub-families are crucial to environmental stress responses and responses to growth factors that cause transcriptional activation of genes required for cell proliferation, differentiation and programmed cell death. Small molecular compounds with specific structure/activity characteristics have been developed that competitively block SAPK/MAPK binding to ATP. Chemically modified compounds based on ATP binding pocket characteristics have improved selectivity and specificity for SAPK/MAPK isoforms. In addition, site-specific mutagenesis of MAPKs has helped identify the MAPK structures required for binding recognition and selectivity of these inhibitors. A group of extracellular-signal regulated protein kinase (ERK) inhibitors has been constructed based almost exclusively on their ability to inhibit the ERK activation cascade. Inhibitors have been employed in vitro to identify protein targets and mechanism of action of SAPKs/MAPKs. The efficacy of SAPK/MAPK inhibitors in animal models of inflammation, arthritis, heart failure, cancer and neurological degeneration has provided the impetus for using them in human studies of inflammation and in clinical trials.

A comprehensive approach to enhancing sexual health education in the Case Western Reserve University School of Medicine.

We report on the Sexual Health Curriculum Enhancement project at Case Western Reserve University School of Medicine. Using a US dollars 100000 grant from Pfizer Pharmaceuticals, Inc., we have developed and are in the process of implementing a comprehensive, cross-disciplinary and innovative curriculum that is based on three primary objectives for teaching sexual health: attitude change, behavior change, and knowledge acquisition. Five general strategies to incorporate specific sexual health content into the medical school curriculum have been implemented: (1). Faculty Development; (2). Additional Didactics; (3). Cased-Based Learning; (4). Testing and Assessment; and (5). Electronic (Computer/Web-Based Enhancements).

Expression profile of protein tyrosine kinase genes in human osteoarthritis chondrocytes.

OBJECTIVE: To determine the expression profile of protein kinase (PK) and protein tyrosine kinase (PTK) genes in human primary osteoarthritis (OA) chondrocytes and to compare it with that of immortalized human chondrocytes T/C 28a4 with a view to learning whether T/C 28a4 cells can be used for elucidating signal transduction pathways in human chondrocytes. DESIGN: We used the Atlas Human cDNA Array and a method based on PCR with degenerate primers to analyse the expression profile of protein kinase genes in primary human OA chondrocytes and compared it with that of immortalized human chondrocyte cell line T/C 28a4 using RT-PCR and Western blotting. RESULTS: A total of 21 PTK genes were identified and several of these have never been shown to be expressed in human OA chondrocytes. Comparative expression analysis of some selected kinase genes showed that the mRNA expression pattern of many protein kinase genes in OA chondrocytes was identical to that of T/C 28a4 cells. However, there were differences in the level of protein expression of selected protein kinases in these cells. For example, mRNA expression of the novel kinase HCK was detected in OA chondrocytes and in the cell lines analysed but by Western blotting HCK protein was not detected in OA chondrocytes. In these studies, we also identified a novel mutant form of the discoidin domain receptor 2 (DDR2) transcript from chondrocyte-like cell line HTB-94. CONCLUSIONS: Our results provide novel information about protein kinase gene expression in OA chondrocytes and indicate that the transformed chondrocyte cell line T/C 28a4 may be suitable for elucidating signal transduction pathways in chondrocytes and to investigate how they regulate chondrocyte function in inflammatory and degenerative joint diseases.

Involvement of caspase-3 in epigallocatechin-3-gallate-mediated apoptosis of human chondrosarcoma cells.

Green tea polyphenol-(-)epigallocatechin-3-gallate (EGCG)-is a potent chemopreventive agent in many test systems and has been shown to inhibit tumor promotion and induce apoptosis. In this study we describe a novel observation that EGCG displayed strong inhibitory effects on the proliferation and viability of HTB-94 human chondrosarcoma cells in a dose-dependent manner and induced apoptosis. Investigation of the mechanism of EGCG-induced apoptosis revealed that treatment with EGCG resulted in DNA fragmentation, induction of caspase-3/CPP32 activity, and cleavage of the death substrate poly(ADP-ribose)polymerase (PARP). Pretreatment of cells with a synthetic pan-caspase inhibitor (Z-VAD-FMK) and a caspase-3-specific inhibitor (DEVD-CHO) prevented EGCG-induced PARP cleavage. The induction of apoptosis by EGCG via activation of caspase-3/CPP32-like proteases may provide a mechanistic explanation for its antitumor effects.

Tumour necrosis factor alpha enhances the expression of hydroxyl lyase, cytoplasmic antiproteinase-2 and a dual specificity kinase TTK in human chondrocyte-like cells.

Tumour necrosis factor alpha (TNF-alpha) is a cytokine with pleiotropic effects on cells ranging from proliferation to apoptosis. These biological effects of TNF-alpha are believed to be elicited by the induction or enhancement of the expression of TNF-alpha responsive genes in the target cells. TNF-alpha is pro-inflammatory and a principal mediator in the pathogenesis of arthritis. The activation of an inflammatory cascade by TNF-alpha in arthritis results in the degradation of cartilage, joint destruction and loss of function. Because TNF-alpha is an important mediator in the pathogenesis of arthritis, the present study addresses the identification of novel TNF-alpha responsive genes in HTB-94 cell line which is of human origin and maintains a chondrocytic phenotype. The three identified cDNAs were previously not known to be induced or upregulated by TNF-alpha in chondrocytes or cells of chondrocytic lineage. One of the identified cDNAs had sequence similarity to human hydroxyl lyase mRNA (PLOD), an enzyme involved in collagen biosynthesis and its metabolism; the second cDNA had sequence similarity to the human cytoplasmic anti-proteinase-2 mRNA (CAP-2), a member of a group of proteins shown to be associated with protecting cells from TNF-alpha-induced apoptosis; and the third cDNA had sequence similarity to a dual specificity kinase, TTK, which is associated with cell proliferation. Relative gene expression level analysis by PCR and by Northern blotting revealed that treatment with TNF-alpha enhanced the expression of PLOD, CAP2 and TTK transcripts which confirmed the results obtained with display gels. Furthermore, TTK mRNA expression was also induced in human articular chondrocytes treated with TNF-alpha but not in untreated chondrocytes. Our results suggest that these genes may play a role in chondrocytic responses to TNF-alpha-mediated stimuli affecting the cartilage homeostasis.

Metabolic disturbances and synovial joint responses in osteoarthritis.

Previously held views that the pathogenesis of idiopathic osteoarthritis (OA) originated in the synovial joint and was not influenced by systemic metabolic disturbances in the patient is inconsistent with recent data demonstrate skewing of the growth hormone/insulin-like growth factor-1 axis in the symptomatic OA patient. In light of this novel information, the role of growth hormone and insulin-like growth factor-1 in the pathogenesis and progression of OA requires further definition. In male patients with OA, the red blood cell sequesters more growth hormone than an aged-matched control group. Thus, this growth hormone "depot" may provide a mechanism for removal of "toxic" levels of growth hormone from the circulation. Storage of "excess" growth hormone in red cells may reduce the inflammatory or otherwise undesirable "toxic" actions of GH. In some patients, serum growth hormones levels may exceed three-times the average value considered normal. These "episodic" variations in growth hormone levels may play a significant role in the elevated levels of serum growth hormone seen in the OA patient. The connection between elevated growth hormone and decreased insulin-like growth factor-1 levels and the defined cartilage anabolic and catabolic pathways defined in in vitro assays of articular cartilage derived from the OA patients remain to be more precisely defined. However, the dampened insulin-like growth factor-1 response in OA coupled with elevated cartilage extracellular matrix degradation (mediated by metalloproteinases) and depressed compensatory biosynthesis (induced and perpetuated by the presence of cytokines such as interleukin-1 and tumor necrosis factor-alpha) may, in fact, act synergistically to suppress normal cartilage repair mechanisms thus resulting in progressive destructive lesions of the cartilage and bone.

Fundamental pathways in osteoarthritis: an overview.

Osteoarthritis (OA) is a significant world-wide health problem owing to the progressive and debilitating nature of the condition which results in high morbidity and a marked decrease in the quality of life. Significant advances in the medical and surgical management of OA have resulted from an understanding of the fundamental pathways governing the health and disease of synovial joint tissues. Continuing investigations into the nature of synovial joint pathophysiology at both the molecular and biochemical level should pave the way for the development of novel therapeutic strategies, including gene therapy and tissue engineering, in the treatment of the OA patient.

Future directions for research and treatment of osteoarthritis.

Future directions in the research and treatment of osteoarthritis (OA) will be based on the emerging picture of pathophysiological events that govern the initiation and progression of OA. The fundamental event resulting in the destruction of articular cartilage in OA arises from an imbalance between anabolic and catabolic pathways. The extracellular matrix (ECM) of cartilage is degraded by matrix metalloproteinases (MMPs) induced by cytokines. Cytokines also blunt chondrocyte compensatory synthesis pathways required to restore the integrity of the degraded ECM. Inhibition of the MMPs, their activators, and cytokines that induce MMP gene up-regulation would appear to be fertile targets for drug development in the treatment of OA. Restoration of damaged articular surfaces via tissue engineering strategies which could employ chondroprogenitor cells in biomatrices appropriate for transplantation to cartilage surfaces appears feasible. A reduction in cytokine-mediated up-regulation of MMP gene expression as well as augmentation of cartilage ECM biosynthesis may also be possible by employing the principles of gene transfer using suitable vectors that establish long-term stable expression of genes which suppress MMPs while at the same time supporting cartilage ECM biosynthesis.

Changes in third carpal bone articular cartilage after synovectomy in normal and inflamed joints.

OBJECTIVE: To determine if arthroscopic synovectomy in normal and inflamed joints had temporal or site-related effects on articular cartilage. STUDY DESIGN: Alterations in equine third carpal bone articular cartilage were studied at two time periods: groups 1 and 2 (6 weeks) and groups 3 and 4 (2 weeks) after synovectomy in normal (groups 2 and 4) and inflamed carpi (groups 1 and 3). ANIMAL POPULATION: 16 carpi from eight horses. METHODS: Biochemical and biomechanical properties of dorsal and palmar articular cartilage were determined by radioloabeling, proteoglycan (PG) extraction, chromatography, electrophoresis, and indentation testing. RESULTS: Synovectomy in inflamed joints produced the greatest concentration of newly synthesized PG in articular cartilage by 2 weeks. Synovectomy in normal joints produced significantly greater newly synthesized PG in articular cartilage by 6 weeks. Dorsal sites had greater newly synthesized and endogenous PG in some groups. Chromatographic profiles of newly synthesized PG demonstrated early and late PG peaks. Electrophoresis of late PG peak showed a toluidine blue-positive band that comigrated with human A1D1 PG monomer in the two groups with the most newly synthesized PG> This band was reactive with monoclonal antibody 1C6 specific for the hyaluronic acid-binding region of aggrecan. For the material properties evaluated, only Poisson's ratio was significantly decreased between groups as a function of time (6 weeks < 2 weeks). and this was most pronounced in the thicker dorsal sites. CONCLUSIONS: Synovectomy in inflamed joints produced site-specific, significantly greater responses in articular cartilage as compared with synovectomy in normal joints. CLINICAL RELEVANCE: Synovectomy may not be beneficial to the articular cartilage in inflamed joints.

Effect of synovial membrane infection in vitro on equine synoviocytes and chondrocytes.

OBJECTIVE: To determine the functional response of synovium to infection, and the influence of infected synovium on articular cartilage metabolism. SAMPLE POPULATION: Synovium and articular cartilage explants from the midcarpal and tarsocrural joints of adult horses. PROCEDURE: For experiment 1, synovium explants were incubated as follows: control--incubation in standard medium, infected (I)--incubation with Staphylococcus aureus, and infected-filtered (IF)--incubation with medium collected from the infected group and filtered (0.22-micron filter). Daily collected medium was assayed for interleukin 1 beta (IL-1 beta), IL-6, tumor necrosis factor, and hyaluronan (HA) concentrations. For experiment 2, cartilage explants were incubated as follows: control--incubation in standard medium, and IF--incubation in medium collected from infected synovium cultures and filtered. After 48 hours, explant proteoglycan synthesis and endogenous proteoglycan and glycosaminoglycan contents were determined. RESULTS: IL-1 beta and IL-6 values were significantly increased in synovium explants from the I and IF groups. Hyaluronan concentration was lower in I and IF groups. Proteoglycan synthesis and content, and total glycosaminoglycan and chondroitin sulfate concentrations, were significantly decreased in cartilage from the IF group. CONCLUSIONS: Bacterial infection was associated with decreased HA concentration and increased mediator release. These effects were also observed despite elimination of bacteria. Exposure to sterile but previously infected medium decreased articular cartilage matrix synthesis and composition. CLINICAL RELEVANCE: Resident synovial cells may contribute appreciably to articular damage during bacterial infection in the absence of migrant inflammatory cells. This response is prolonged despite elimination of the bacteria.

Biochemical, histochemical, and immunohistochemical characterization of distal tibial osteochondrosis in horses.

OBJECTIVE: To compare the biochemical, histochemical, and immunohistochemical profiles of articular cartilage from horses with naturally acquired distal tibial osteochondrosis (OC) with cartilage from a similar location in clinically normal horses. ANIMALS: 9 affected horses (group 1, 16 OC lesions) and 4 control horses (group 2, 8 normal osteochondral specimens). PROCEDURE: OC specimens were collected during arthroscopic removal of the fragment, and control specimens were collected by aseptic osteotomy. Uronic acid, total protein, total glycosaminoglycan (GAG), chondroitin sulfate (CS), and keratan sulfate (KS) contents were determined. Histomorphologic, histochemical, and immunohistochemical examinations were performed on specimens after snap freezing at -80 C and cryosectioning. Monoclonal antibodies (MAB) 3B3 and 5D4 were applied for location of epitopes of CS and KS, respectively. RESULTS: OC lesions had significantly lower quantity of uronic acid, total GAG, and CS, compared with normal cartilage. OC cartilage had significantly less intense staining with toluidine blue, along with irregular cellularity and tidemark characteristics, compared with normal cartilage. Monoclonal antibodies 3B3 and 5D4 stained OC cartilage, whereas MAB 5D4 did not stain control cartilage. Additionally, MAB 3B3 and 5D4 stained the fibrous tissue that was found firmly attached to the OC lesion located between the parent distal portion of the tibia and OC fragment. CONCLUSION: OC cartilage lesions of the distal intermediate ridge of the tibia in horses are biochemically, histochemically, and immunohistochemically distinct from normal cartilage from the same location. Results may reflect the inability of the chondrocyte of the developing joint to alter matrix components that would allow proper maturation and differentiation into bone.

Biochemical and biomechanical alterations in equine articular cartilage following an experimentally-induced synovitis.

The effects of inflammation on the biochemical and biomechanical properties of articular cartilage at two sites (dorsal and palmar) from the radial facet of the equine third carpal bone were examined in response to a synovitis induced with Escherichia coli lipopolysaccharide (LPS). Four groups were studied. In group 1 synovitis was induced at time zero and evaluated at week 6. Group 2 was the sham-treated control for group 1. In group 3 synovitis was induced at time zero and evaluated at week 2. Group 4 was the sham-treated control for group 3. There was a significant increase (P < 0.05) in newly synthesized proteoglycan PG from both sites in group 3 as compared to the sham-treated groups and group 1. No significant difference in the endogenous PG concentration between groups or sites was detected. Sepharose CL-2B revealed two peaks of newly synthesized PG in all groups; an early peak (Kav 0.11-0.13) and a late peak (Kav 0.48-0.64). Newly synthesized PG profiles from sham-treated groups and group 3 were similar, but the group 3 PG profile exhibited a more pronounced early peak. Conversely, the PG profile from group 1 demonstrated a more prominent late peak. Electrophoresis and Western blot analysis of the pooled late PG peak fractions from the sham-treated and group 1 showed a single toluidine blue stained band from both sites which reacted with monoclonal antibody (MAb) 1C6. By contrast, the late peak from the palmar site in group 3 showed an additional faster moving component on composite gels which did not react with MAb 1C6. There was a significant decrease in Poisson's ratio and a significant increase in cartilage thickness in groups 1 and 3 which had received synovitis. The increase in cartilage thickness of groups 1 and 3 was also significantly affected by site (dorsal > palmar). There was no significant difference in aggregate modulus or permeability constant among groups. Primary joint inflammation induced by LPS alters the biochemical and biomechanical properties of the articular cartilage as a function of time and site. An increase in chondrocyte PG synthesis in the early period following synovitis may be a reparative response to the inflammatory insult. Continued alterations in the qualitative PG composition in the later period following synovitis may represent a shift in chondrocyte metabolism to repopulate the existing cartilage matrix.

A potent inhibitor of neurite outgrowth that predominates in the extracellular matrix of reactive astrocytes.

In a model of astrogliosis in vitro, cultured cortical astrocytes were triggered into a functionally reactive state by an immobilized fragment of the beta-amyloid peptide. Induced astrocytes produced an extracellular matrix that inhibited the outgrowth of embryonic CNS axons. Within the extracellular matrix deposited by reactive astrocytes, we found an overall increase in the deposition of chondroitin sulphate that accounted for the inhibition. Specifically, we have detected an increased biosynthesis of a small chondroitin/heparan sulphate proteoglycan that is a potent inhibitor of axon outgrowth. We further suggest that this proteoglycan, or related molecules yet to be discovered, may play a role in gliosis-mediated regenerative failure of CNS axons.

Phenotypic modulation of newly synthesized proteoglycans in human cartilage and chondrocytes.

The proteoglycans synthesized by human osteoarthritic femoral head cartilage and nonarthritic articular cartilage age-matched to the osteoarthritic cartilage specimens was studied in explant cultures and in chondrocytes generated by explant outgrowth from the cartilages. Twenty-four hours after explanation, both nonarthritic articular cartilage and osteoarthritic cartilage synthesized principally one large proteoglycan core protein that migrated on 3-5% acrylamide gels with an apparent molecular mass (M(r)) of approximately 520 kDa after enzymatic digestion with chondroitinase ABC and keratanase. The proteoglycan was found in both the explant itself and in the medium compartment of the culture as well. This proteoglycan contained chondroitin-6-sulfate, keratan sulfate and the hyaluronan binding region as evidenced by immunoblotting with murine anti-proteoglycan monoclonal antibodies indicating that the proteoglycan was aggrecan. To a much lesser extent two additional proteoglycan core proteins were also found in the explant but were not seen in the culture medium compartment. These proteoglycans possessed apparent M(r)'s of approximately 480 kDa and approximately 390 kDa on 3-5% acrylamide gels after chondroitinase ABC and keratanase digestion. The medium compartment contained principally the approximately 520 kDa proteoglycan core protein. In osteoarthritic cartilage explants, the pattern of newly synthesized proteoglycans recovered from the tissue as assessed on 3-16% polyacrylamide gradient gels remained relatively the same from day 1 after explantation up to 36 days of culture. By contrast, the proteoglycans recovered from the culture medium contained chondroitin sulfate and keratan sulfate after 1, 7, and 21 days in culture but by 36 days appeared to contain only chondroitin sulfate. Chondrocytes generated from osteoarthritic cartilage and age-matched nonarthritic articular cartilage synthesized different patterns of large (greater than 200 kDa) proteoglycan. Whereas chondrocytes derived from osteoarthritic cartilage continued to synthesize principally the approximately 520 kDa proteoglycan core protein, the chondrocytes derived from nonarthritic cartilage synthesized in addition to this proteoglycan, abundant amounts of the other two proteoglycan core proteins as well.

Site-specific proteoglycan characteristics of third carpal articular cartilage in exercised and nonexercised horses.

The relevance of site and the influence of exercise on third carpal articular cartilage proteoglycan (PG) were assessed in 16 horses. Six horses were exercised (exercised group) for 30 minutes, 3 times/wk, for 6 weeks. The other 10 horses (nonexercised group) were housed in box stalls for the same 6-week period. At week 6, articular cartilage from the proximal surface of the right third carpal bone was harvested and cultured with radioactive sulfate to label newly synthesized PG. Endogenous PG was measured by use of a uronic acid assay. Newly synthesized and endogenous PG were characterized by use of Sepharose CL-2B chromatography, composite gel electrophoresis, and/or immunoblot analysis with monoclonal antibody 1C6 directed against the hyaluronic acid-binding region on PG. There was a significant (P = 0.0002) effect of exercise, but not site, on newly synthesized PG, which was increased in the exercised horses, compared with the nonexercised horses at the end of the 6-week study period. The increase in newly synthesized PG was not reflected in the existing cartilage matrix as there was no significant difference between groups in endogenous PG. However, there was a significant (P = 0.01) effect of site on endogenous PG, with the nest of sites located in the palmar aspect of the radial facet containing a greater concentration of endogenous PG than the nests of sites located on the dorsal aspect of the radial facet or all sites on the intermediate facet. Most newly synthesized PG in both groups consisted of hydrodynamically small PG monomers. However, there was a change in the profile of newly synthesized PG at some sites in the exercised horses to include an early elution peak on Sepharose CL-2B, which may contain aggregating PG. All sites in both groups contained a diverse population of endogenous large and small PG on toluidine blue-stained composite gels that reacted with monoclonal antibody 1C6, indicating the potential to bind to hyaluronic acid.

Biomechanical properties of third carpal articular cartilage in exercised and nonexercised horses.

The relevance of site and exercise on the biomechanical properties of the articular cartilage from the equine third carpal bone were assessed by creep indentation testing. Six horses were exercised for 30 minutes three times weekly. Another six horses were housed in box stalls and were not exercised. At the conclusion of the study, one third carpal bone from each horse was harvested and the KLM biphasic material properties of cartilage were determined at 12 sites. There was a significant (p < 0.01) effect of site but not exercise on the cartilage aggregate modulus, which was significantly lower for sites on the dorsal aspect of the radial facet and for all sites on the intermediate facet as compared with sites on the palmar aspect of the radial facet of the third carpal bone. Exercise significantly increased the permeability constant at all sites when compared with the nonexercised group, but there was no difference between sites within groups. Exercise also significantly increased Poisson's ratio, but only at sites located on the palmar aspect of the radial facet. In general, both site and exercise influence the biomechanical behavior of third carpal articular cartilage. Inherent differences in cartilage biomechanical properties within a joint correlate with the location specificity of cartilaginous lesions in the equine midcarpal joint.

Synthesis of aggrecan core proteins by human cartilage and chondrocytes in vitro.

Proteoglycans synthesized by human cartilage were studied in explants and in chondrocyte cultures. The D1 fraction proteoglycans radiolabelled with 35SO4 were analyzed by 3-16% sodium dodecyl sulfate polyacrylamide gel electrophoresis or on 3-5% acrylamide gels. After 24 h in culture, osteoarthritic and age matched nonarthritic cartilage synthesized one aggrecan core protein (LI) whose apparent size after chondroitinase ABC/keratanase digestion was approximately 520 kDa. Three proteoglycan core proteins were found in the D1 fraction of the medium compartment of nonarthritic chondrocytes, whose apparent sizes were approximately 520 kDa (LI), approximately 390 kDa (LII), and approximately 480 kDa (LIII). The LII and LIII core proteins were routinely absent from osteoarthritic chondrocytes. Chondrocytes from a 28-year-old patient with osteoarthritis secondary to congenital hip dysplasia synthesized principally the LI proteoglycan core protein.

Regional differences in reactive gliosis induced by substrate-bound beta-amyloid.

Regions of gliosis surround deposits of beta-amyloid peptide (beta AP) in senile plaques of Alzheimer's disease (AD). The association between reactive astrocytes and beta AP in senile plaques is most pronounced in cortex and hippocampus but not at other anatomical sites of beta AP deposition. We hypothesized that this region-specific pathology in AD could be attributed to differences in glial reactivity in different parts of the central nervous system (CNS). To test this hypothesis, we assayed astrocytes from cerebral cortex, hippocampus, cerebellum, and spinal cord for cellular responsiveness to substrate-bound beta AP in vitro. Astrocyte reactivity was monitored by morphological changes, increased deposition of chondroitin sulfate proteoglycan-containing matrix, and alterations in proteoglycan metabolism. Based on these criteria, only cortical and hippocampal astrocytes showed marked reactivity to immobilized beta AP. In cortical and hippocampal cultures only, immobilized beta AP resulted in increased total radiosulfate incorporation into proteoglycans which was mainly found in the cell/matrix rather than in the media-associated compartment. There were also differences in the proteoglycan synthesis patterns of astrocyte cultures isolated from these CNS regions. These findings suggest that (1) astrocytes are regionally heterogenous in their reactive response to beta AP and (2) that specific molecules, in addition to beta AP, may exist following trauma or disease which trigger reactive states in astroglia in the cerebellum or spinal cord. These local differences in the interaction between beta AP and surrounding astrocytes may play a role in the region-specific pathogenesis of Alzheimer's disease.