Rheumatoid Arthritis: Pisetsky DS

Pisetsky DS. · Division of Rheumatology and Immunology at the Duke University Medical Center, Durham, NC, USA. · Nat Clin Pract Rheumatol. · Pubmed #18382480 No free full text.

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Pisetsky DS. · No affiliation provided · N Engl J Med. · Pubmed #10717018 No free full text.

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Pisetsky DS, Erlandsson-Harris H, Andersson U. · Division of Rheumatology and Immunology, Duke University Medical Center, Durham, NC, USA. · Arthritis Res Ther. · Pubmed #18598385 links to  free full text

Abstract: High-mobility group box protein 1 (HMGB1) is a non-histone nuclear protein that has a dual function. Inside the cell, HMGB1 binds DNA, regulating transcription and determining chromosomal architecture. Outside the cell, HMGB1 can serve as an alarmin to activate the innate system and mediate a wide range of physiological and pathological responses. To function as an alarmin, HMGB1 translocates from the nucleus of the cell to the extra-cellular milieu, a process that can take place with cell activation as well as cell death. HMGB1 can interact with receptors that include RAGE (receptor for advanced glycation endproducts) as well as Toll-like receptor-2 (TLR-2) and TLR-4 and function in a synergistic fashion with other proinflammatory mediators to induce responses. As shown in studies on patients as well as animal models, HMGB1 can play an important role in the pathogenesis of rheumatic disease, including rheumatoid arthritis, systemic lupus erythematosus, and polymyositis among others. New approaches to therapy for these diseases may involve strategies to inhibit HMGB1 release from cells, its interaction with receptors, and downstream signaling.

Ardoin SP, Pisetsky DS. · Departments of Internal Medicine and Pediatrics, Divisions of Rheumatology and Pediatric Rheumatology, Duke University Medical Center, DUMC Box 3212, Durham, NC 27710, USA. · Mod Rheumatol. · Pubmed #18418695 links to  free full text

Abstract: Cell death is critical to normal homeostasis, although this process, when increased aberrantly, can lead to the production of pro-inflammatory mediators promoting autoimmunity. Two novel intercellular mediators of inflammation generated during cell death are high mobility group box 1 (HMGB1) protein and microparticles (MPs). HMGB1 is a nuclear protein that functions in transcription when inside the nucleus but takes on pro-inflammatory properties when released during cell death. Microparticles are small, membrane-bound structures that extrude from cells when they die and contain cell surface proteins and nuclear material from their parent cells. MPs circulate widely throughout the vasculature and mediate long-distance communication between cells. Both MPs and HMGB1 have been implicated in the pathogenesis of a broad spectrum of inflammatory diseases, including the prototypic autoimmune conditions systemic lupus erythematosus and rheumatoid arthritis. Given their range of activity and association with active disease, both structures may prove to be targets for effective therapy in these and other disorders.

Ardoin SP, Shanahan JC, Pisetsky DS. · Division of Rheumatology and Immunology, Duke University Medical Center, Medical Research Service, Durham VA Hospital, Durham, NC, USA. · Scand J Immunol. · Pubmed #17635793 No free full text.

Abstract: Microparticles (MP) are small membrane-bound vesicles that circulate in the peripheral blood and play active roles in thrombosis, inflammation and vascular reactivity. While MP can be released from nearly every cell type, most investigation has focused on MP of platelet, leucocyte and endothelial cell origin. Cells can release MP during activation or death. Flow cytometry is the usual method to quantify MP; the small size of these structures and lack of standardization in methodology complicate measurement. As MP contain surface and cytoplasmic contents of the parent cells and bear phosphatidylserine, antibodies to specific cell surface markers and annexin V can be used for identification. Through various mechanisms, MP participate in haemostasis and have procoagulant potential in disease. MP contribute to inflammation via their influence on cell-cell interactions and cytokine release, and MP also function in mediating vascular tone. In several disease states characterized by inflammation and vascular dysfunction, MP subpopulations are elevated, correlate with clinical events, and may have important roles in pathogenesis. In the rheumatic conditions such as rheumatoid arthritis and systemic lupus erythematosus, MP are potentially important markers of disease activity and have an increasingly recognized role in immunopathogenesis. It is clear that MP play an important role in atherosclerosis, and study of these structures may provide insight into the link between chronic inflammatory conditions and accelerated atherosclerosis. As biomarkers, MP allow access to usually inaccessible tissues such as the endothelium. Further research will hopefully lead to interventions targeting MP release and function.

Mitchell KL, Pisetsky DS. · Division of Rheumatology and Immunology, Duke University Medical Center, Durham, NC 27705, USA. · Curr Opin Rheumatol. · Pubmed #17414956 No free full text.

Abstract: PURPOSE OF REVIEW: Rheumatoid arthritis is a chronic inflammatory disease in which early aggressive therapy with disease-modifying antirheumatic drugs can improve outcome and prevent joint damage. While such therapy is effective, its application can be limited by diagnostic uncertainty in patients with early inflammatory arthritis and concerns about treatment of patients whose disease would remit spontaneously. The purpose of current research is therefore to identify prognostic markers of early disease and to determine the role of aggressive treatment strategies in inducing remission in such patients. RECENT FINDINGS: Recent research has provided new information on genetic markers predicting rapid progression of joint destruction; the role of serology, in particularly, antibodies to citrullinated peptides in diagnosing rheumatoid arthritis; the utility of radiographic techniques in detecting both early synovitis and bone erosion; and the value of combination therapy in controlling signs, symptoms and radiographic progression. Recent clinical studies support the efficacy of a combination of methotrexate with a biological agent, especially a tumor-necrosis-factor blocker, in reducing disease activity. SUMMARY: While current treatment approaches can produce significant benefits in patients with early arthritis, future investigation is needed to target therapy more selectively and to determine which patients respond best to various agents or combinations.

Jiang W, Pisetsky DS. · Department of Medicine, Duke University Medical Center, Durham, NC 27705, USA. · Nat Clin Pract Rheumatol. · Pubmed #17203009 No free full text.

Abstract: High-mobility group protein 1 (HMG1) is a nonhistone nuclear protein that is a prototype of a dual-function alarmin whose immune activity is dependent upon its cellular location. Inside the cell, HMG1 binds to DNA and has a role in transcriptional regulation. Outside the cell, HMG1 acts as a cytokine and has activities that resemble those of tumor necrosis factor. The cytokine activities of HMG1 become manifest when this protein translocates from the nucleus to the cytoplasm and, eventually, into the external milieu; this translocation occurs during cell activation and cell death. Given its cytokine activity, HMG1 has been implicated in the pathogenesis of a broad range of immune-mediated diseases including arthritis. The role for this protein in arthritis was established by observations of the expression of HMG1 in synovial tissue of patients with rheumatoid arthritis as well as in the joints of animals used to model arthritis. Furthermore, in the mouse model of collagen-induced arthritis, treatment with antibodies to HMG1 or to an inhibitory domain of HMG1 can attenuate joint inflammation and damage. These studies identify a novel pathway in the pathogenesis of inflammatory arthritis, as well as a new target for biologic therapy.

Pisetsky DS. · Departmentof Medicine, Division of Rheumatology and Immunology, Duke UniversityMedical Center, Durham, NC, USA. · Bull NYU Hosp Jt Dis. · Pubmed #17121482 links to  free full text

Abstract: Rheumatology has made remarkable advances in patient treatment in the past decade related to the impressive array of new drugs that have been approved or are undergoing clinical trial. While this situation should engender optimism for the future, concerns about sustaining momentum have been raised. These concerns relate to uncertainty in the research agenda for major diseases such as osteoarthritis and fibromyalgia, lack of informatics systems to allow accurate assessment of risks and benefits of new treatments, and a paucity of clinical trials in rheumatoid arthritis aimed at sustained remission or cure. Fortunately, the opportunities for the future remain very bright because of burgeoning research in biomedicine and outcomes assessment as well as progress in developing personalized medicine to individualize treatment better.

Pisetsky DS, St Clair EW. · Division of Rheumatology, Allergy, and Clinical Immunology, Duke University Medical Center, 1516 Durham Veterans Affairs Medical Center, Box 151G, Durham, NC 27710, USA. · JAMA. · Pubmed #11735734 No free full text.

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Rice JR, Pisetsky DS. · Division of Rheumatology, Allergy, and Clinical Immunology, Duke University Medical Center, Durham, North Carolina, USA. · Rheum Dis Clin North Am. · Pubmed #10083957 No free full text.

Abstract: Patients with rheumatic disease experience pain that can be intense, persistent, and disabling. This pain is frequently multifactorial in origin and has both central and peripheral components. Because of the array of conditions that can cause musculoskeletal pain, patient management must begin with a complete clinical assessment that identifies possible etiologies and measures objective findings against subjective complaints. Especially in patients with known rheumatic disease, the possibility of concurrent pain of central origin must be considered and appropriate treatment given. By applying a comprehensive therapy plan of drugs, physical therapy, and patient education, significant benefits can often be achieved in this prevalent group of painful diseases.

St Clair EW, Wilkinson WE, Pisetsky DS, Sexton DJ, Drew R, Kraus VB, Greenwald RA. · Duke University Medical Center, Durham, North Carolina 27710, USA. · Arthritis Rheum. · Pubmed #11357896 links to  free full text

Abstract: OBJECTIVE: To determine the feasibility, safety, and potential clinical efficacy of intravenous (IV) doxycycline therapy for rheumatoid arthritis (RA), as well as its possible effects on serum and urinary markers of collagen breakdown. METHODS: The exploratory trial was designed as a 16-week, single-center, randomized, double-blind, placebo-controlled trial. Eligible subjects with active seropositive or erosive RA were randomly allocated into 3 treatment groups: doxycycline 200 mg IV, azithromycin 250 mg orally, or placebo. The blinded IV study drug was administered once daily for the first 3 weeks by home self-infusion and then weekly for the next 8 weeks, concurrent with the blinded oral study drug at the prescribed doses. The primary end points were the change between baseline and week 4 in the tender joint count, erythrocyte sedimentation rate, and urinary excretion of pyridinoline. RESULTS: The trial was stopped prematurely after enrollment of 31 patients. Three subjects were withdrawn because of worsening arthritis, and 1 patient was withdrawn when newly diagnosed with breast cancer. Infusion-related events occurred in 13 (42%) of 31 patients, but none were serious. There were 4 serious adverse events unrelated to the study drug, including a new diagnosis of breast cancer in 3 cases and hospitalization for abdominal pain in 1 case. No significant differences were observed across treatment groups in any of the 3 primary clinical end points. CONCLUSION: Although IV doxycycline therapy was generally well-tolerated by patients in this trial, it did not show any evidence of reducing disease activity or collagen crosslink production.

Pisetsky DS. · Duke University Medical Center, Durham, North Carolina, USA. · Arthritis Rheum. · Pubmed #18240202 links to  free full text

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Pisetsky DS. · Durham VA Medical Center, 508 Fulton Street, Durham, NC 27705, USA. · Health Psychol. · Pubmed #18020835 No free full text.

Abstract: The arthritic diseases are major sources of pain or disability, although they differ in etiology and treatment approach. For diseases such as RA, inflammation is the predominant mechanism that leads to systemic complaints such as pain as well as local destruction of cartilage and bone. In contrast, OA is primarily a degenerative process and, although inflammation may occur, it differs in quality and extent from that in the systemic inflammatory arthritidies. For both conditions, psychosocial interventions have significant positive benefits, but their application involves careful consideration of a variety of factors. These factors include the following: diagnosis, disease activity, damage, disease stage, patient age and demographics, presence of comorbidities, and availability of alternative or adjunctive approaches.

Jüngel A, Distler O, Schulze-Horsel U, Huber LC, Ha HR, Simmen B, Kalden JR, Pisetsky DS, Gay S, Distler JH. · Zurich Center of Integrative Human Physiology, and University Hospital Zurich, Zurich, Switzerland. · Arthritis Rheum. · Pubmed #17968936 links to  free full text

Abstract: OBJECTIVE: Microparticles are small vesicles that are released from activated or dying cells and that occur abundantly in the synovial fluid of patients with rheumatoid arthritis (RA). The goal of these studies was to elucidate the mechanisms by which microparticles activate synovial fibroblasts to express a proinflammatory phenotype. METHODS: Microparticles from monocytes and T cells were isolated by differential centrifugation. Synovial fibroblasts were cocultured with increasing numbers of microparticles. Gene expression was analyzed by real-time polymerase chain reaction and confirmed by Western blotting and enzyme immunoassay. Arachidonic acid labeled with tritium was used to study the transport of biologically active lipids by microparticles. The roles of NF-kappaB and activator protein 1 (AP-1) signaling were analyzed with electrophoretic mobility shift assay and transfection with small interfering RNA and IkappaB expression vectors. RESULTS: Microparticles strongly induced the synthesis of cyclooxygenase 2 (COX-2), microsomal prostaglandin E synthase 1 (mPGES-1), and prostaglandin E(2) (PGE(2)). In contrast, no up-regulation of COX-1, mPGES-2, cytosolic PGES, or phospholipase A(2) was observed. The induction of PGE(2) was blocked by selective inhibition of COX-2. Microparticles activated NF-kappaB, AP-1, p38, and JNK signaling in synovial fibroblasts. Inhibition of NF-kappaB, AP-1, and JNK signaling reduced the stimulatory effects. Arachidonic acid was transported from leukocytes to fibroblasts by microparticles. Arachidonic acid derived from microparticles was converted to PGE(2) by synovial fibroblasts. CONCLUSION: These results demonstrate that microparticles up-regulate the production of PGE(2) in synovial fibroblasts by inducing COX-2 and mPGES-1. These data provide evidence for a novel mechanism by which microparticles may contribute to inflammation and pain in RA.

Zetterström CK, Jiang W, Wähämaa H, Ostberg T, Aveberger AC, Schierbeck H, Lotze MT, Andersson U, Pisetsky DS, Erlandsson Harris H. · Department of Woman and Child Health, Pediatric Rheumatology Research Unit, Karolinska Institutet/Karolinska University Hospital, Stockholm, Sweden. · J Leukoc Biol. · Pubmed #17913975 links to  free full text

Abstract: Gold compounds such as gold sodium thiomalate (GST) can reduce the symptoms of rheumatoid arthritis (RA), although their mechanism of action is not well defined. As the proinflammatory mediator high mobility group box chromosomal protein 1 (HMGB1) may play a role in the pathogenesis of RA, we have performed in vitro studies to investigate whether GST inhibits HMGB1 release as the basis of its mode of action. Murine RAW 264.7 or human THP-1 macrophage cells were stimulated in culture with agents causing extracellular HMGB1 release, including LPS, IFN-gamma, polyinosinic:polycytidylic acid, IFN-beta, or NO in the presence of GST, ranging from 0 microM to 250 microM. Secretion and intracellular location of HMGB1 were assessed by Western blotting, HMGB1-specific ELISPOT assay, and immunofluorescent staining. In parallel, TNF and IFN-beta levels were analyzed by ELISPOT and/or ELISA. Supernatant NO production was analyzed by the Griess method. At pharmacologically relevant doses, GST inhibited the extracellular release of HMGB1 from activated macrophages and caused the nuclear retention of this protein; in contrast, no effects were observed on the secretion or production of TNF. Release of the key endogenous mediators of HMGB1 translocation, IFN-beta and NO, was inhibited by GST. This inhibition required gold, as sodium thiomalate did not affect the responses measured. Furthermore, gold chloride also inhibited release of HMGB1. Together, these results suggest a new mechanism for the anti-rheumatic effects of gold salts in RA and the potential of drugs, which interfere with intracellular HMGB1 transport mechanisms, as novel agents to treat RA.

Taylor HA, Sugarman J, Pisetsky DS, Bathon J. · Berman Institute of Bioethics, Department of Health Policy and Management, Johns Hopkins University, Hampton House, 353 624 N Broadway, Baltimore, MD 21205, USA. · Ann Rheum Dis. · Pubmed #16984939 No free full text.

Abstract: In preparation for randomised controlled trials (RCTs) of disease-modifying antirheumatic drugs in patients with early inflammatory arthritis (EIA), formative research was conducted to enhance the design of such trials. The objectives of this research were to (1) determine patients' educational needs as they relate to the necessary elements of informed consent; and (2) assess patients' interest in enrolling in a hypothetical prevention trial. In-depth interviews were conducted with nine patients. Seven patients were women and all but one white. The mean age was 48 years. During the 4-month enrolment period, only three patients with EIA were identified; six patients with longer duration of symptoms were also interviewed. Most patients were able to express the primary aim of a hypothetical prevention trial presented. Factors cited by patients favouring enrolment were potential for direct medical benefit and knowledge that they would be withdrawn from the trial if they developed symptoms. Factors cited by patients against enrolment were the inclusion of a placebo and general uncertainty regarding treatment required by the RCT design. Pending larger-scale empirical projects to explore patients' attitudes about prevention trials, small-scale formative research in advance of such trials ought to be conducted.

Weinberg JB, Lang T, Wilkinson WE, Pisetsky DS, St Clair EW. · Veterans Affairs Medical Center, 508 Fulton Street, Durham, NC 27705, USA. · Arthritis Res Ther. · Pubmed #16907988 links to  free full text

Abstract: Nitric oxide (NO) may play important roles in rheumatoid arthritis (RA). RA is an inflammatory disease involving joints and other systems including salivary glands. To assess NO production in RA patients, we compared levels of serum, urine, and salivary nitrite and nitrate (NOx) in patients with RA and normal subjects, and we examined the relationships of these measures to disease activity. Serum, urine, and NOx levels as well as renal creatinine, NOx clearance and fractional excretion rates were compared in 25 RA patients and 20 age- and gender-matched healthy controls. Subjects were hospitalized for 3 days and placed on a NOx restricted diet. NOx was assayed using nitrate reductase and the Griess reagent. RA activity was assessed using standard clinical and laboratory measures. While consuming a restricted diet for 3 days to eliminate the effects of oral intake of NOx, 24 hour urinary NOx excretion decreased in both RA patients and healthy controls. Urine NOx levels at all time points were not significantly different between RA patients and normal subjects. Serum NOx levels also decreased during the 3 days of NOx restriction, but RA patients had higher serum NOx levels at all time points compared with the control group. Likewise, serum NOx/creatinine ratios were higher in RA patients than in controls. Although basal salivary flow rate and tear flow were lower in RA patients, salivary NOx levels did not differ between normal and RA subjects. While renal creatinine clearance was not different between the two groups, we found that RA patients had lower renal NOx clearance and lower renal NOx fractional excretion. After correction of p values for multiple comparisons, there were no significant relationships for the RA group between measures of disease activity and the urinary NOx, serum NOx, or urinary NOx clearance. Despite interest in the use of NO as a marker of disease activity, alterations in renal NOx clearance and fractional excretion in RA make it difficult to assess in vivo NO production even with strict dietary restriction of NOx intake.

Distler JH, Jüngel A, Huber LC, Seemayer CA, Reich CF, Gay RE, Michel BA, Fontana A, Gay S, Pisetsky DS, Distler O. · Center of Experimental Rheumatology, Department of Rheumatology, University Hospital Zurich, CH-8091 Zurich, Switzerland. · Proc Natl Acad Sci U S A. · Pubmed #15701693 links to  free full text

Abstract: Rheumatoid arthritis is a chronic inflammatory disease characterized by destruction of cartilage and bone that is mediated by synovial fibroblasts. To determine the mechanisms by which these cells are activated to produce matrix metalloproteinases (MMPs), the effects of microparticles were investigated. Microparticles are small membrane-bound vesicles whose release from immune cells is increased during activation and apoptosis. Because microparticles occur abundantly in the synovial fluid in rheumatoid arthritis, they could represent novel stimulatory agents. Microparticles derived from T cells and monocytes strongly induced the synthesis of MMP-1, MMP-3, MMP-9, and MMP-13 in fibroblasts. The induction was time-dependent, with effects primarily observed after 36 h; under these conditions, MMP-2, MMP-14, and tissue inhibitor of MMP-1 (TIMP-1), TIMP-2, and TIMP-3 were not induced. Microparticles also increased the synthesis of inflammatory mediators including IL-6, IL-8, monocyte chemoattractant protein 1 (MCP-1), and MCP-2. In Ikappa-B-transfected synovial fibroblasts, MMPs were less inducible by microparticles compared with wild-type fibroblasts. Blocking of TNFalpha and IL-1beta with antibodies against TNFalpha and with IL-1 receptor antagonist did not abrogate stimulation by microparticles. These data provide evidence for a novel mechanism by which vesicles derived from activated or apoptotic immune cells can promote the destructive activity of synovial fibroblasts in rheumatoid arthritis.

Fermor B, Jeffcoat D, Hennerbichler A, Pisetsky DS, Weinberg JB, Guilak F. · Department of Surgery, Division of Orthopaedic Surgery, Duke University Medical Center, Durham, NC 27710, USA. · Osteoarthritis Cartilage. · Pubmed #15564062 No free full text.

Abstract: OBJECTIVES: Cells of the knee meniscus respond to changes in their biochemical and biomechanical environments with alterations in the biosynthesis of matrix constituents and inflammatory mediators. Tumor necrosis factor alpha (TNF-alpha) is a pro-inflammatory cytokine that is involved in the pathogenesis of both osteoarthritis and rheumatoid arthritis, but its influence on meniscal physiology or mechanobiology is not fully understood. The objectives of this study were to examine the hypothesis that cyclic mechanical strain of meniscal cells modulates the biosynthesis of matrix macromolecules and pro-inflammatory mediators, and to determine if this response is altered by TNF-alpha. METHODS: Cells were isolated from the inner two-thirds of porcine medial menisci and subjected to biaxial tensile strain of 5-15% at a frequency of 0.5Hz. The synthesis of proteoglycan, protein, nitric oxide (NO), and prostaglandin E(2) were determined. RESULTS: Cyclic tensile strain increased the production of nitric oxide through the upregulation of nitric oxide synthase 2 (NOS2) and also increased synthesis rates of prostaglandin E(2), proteoglycan, and total protein in a manner that depended on strain magnitude. TNF-alpha increased the production of NO and total protein, but inhibited proteoglycan synthesis rates. TNF-alpha prevented the mechanical stimulation of proteoglycan synthesis, and this effect was not dependent on NOS2. CONCLUSIONS: These findings indicate that pro-inflammatory cytokines can modulate the responses of meniscal cells to mechanical signals, suggesting that both biomechanical and inflammatory factors could contribute to the progression of joint disease as a consequence of altered loading of the meniscus.

Criscione LG, Sugarman J, Sanders L, Pisetsky DS, St Clair EW. · Duke University Medical Center, Durham, North Carolina 27710, USA. · Arthritis Rheum. · Pubmed #12794792 links to  free full text

Abstract: OBJECTIVE: To evaluate the informed consent process for a clinical trial of intravenous doxycycline for rheumatoid arthritis. METHODS: Participants completed a self-administered questionnaire about the consent process at baseline and 16 weeks following enrollment in a clinical trial. RESULTS: Respondents (n = 30) affirmed voluntary participation in the parent trial. Participants acknowledged hope and altruism as reasons for entering the trial more than expectation of personal benefit or outside influences. Many respondents did not understand randomization (14/30), placebos (15/30), or risks of study medications; 11/30 respondents believed that the study drug was completely safe. CONCLUSION: Respondents generally understood the experimental nature of the trial and confirmed their participation was voluntary. However, gaps existed in participants understanding of trial design, raising the question of whether they were adequately informed about the research study prior to enrollment. Further education of potential participants in clinical trials may be required to achieve valid informed consent.

Jawaheer D, Seldin MF, Amos CI, Chen WV, Shigeta R, Etzel C, Damle A, Xiao X, Chen D, Lum RF, Monteiro J, Kern M, Criswell LA, Albani S, Nelson JL, Clegg DO, Pope R, Schroeder HW, Bridges SL, Pisetsky DS, Ward R, Kastner DL, Wilder RL, Pincus T, Callahan LF, Flemming D, Wener MH, Gregersen PK, Anonymous00340. · Center for Genomics and Human Genetics, Manhasset, New York 11030, USA. · Arthritis Rheum. · Pubmed #12687532 links to  free full text

Abstract: OBJECTIVE: A number of non-HLA loci that have shown evidence (P < 0.05) for linkage with rheumatoid arthritis (RA) have been previously identified. The present study attempts to confirm these findings. METHODS: We performed a second genome-wide screen of 256 new multicase RA families recruited from across the United States by the North American Rheumatoid Arthritis Consortium. Affected sibling pair analysis on the new data set was performed using SIBPAL. We subsequently combined our first and second data sets in an attempt to enhance the evidence for linkages in a larger sample size. We also evaluated the impact of covariates on the support for linkage, using LODPAL. RESULTS: Evidence of linkage at 1p13 (D1S1631), 6p21.3 (the HLA complex), and 18q21 (D18S858) (P < 0.05) was replicated in this independent data set. In addition, there was new evidence for linkage at 9p22 (D9S1121 [P = 0.001]) and 10q21 (D10S1221 [P = 0.0002] and D10S1225 [P = 0.0038]) in the current data set. The combined analysis of both data sets (512 families) showed evidence for linkage at the level of P < 0.005 at 1p13 (D1S1631), 1q43 (D1S235), 6q21 (D6S2410), 10q21 (D10S1221), 12q12 (D12S398), 17p13 (D17S1298), and 18q21 (D18S858). Linkage at HLA was also confirmed (P < 5 x 10(-12)). Inclusion of DRB1*04 as a covariate significantly increased the probability of linkage on chromosome 6. In addition, some linkages on chromosome 1 showed improved significance when modeling DRB1*04 or rheumatoid factor positivity as covariates. CONCLUSION: These results provide a rational basis for pursuing high-density linkage and association studies of RA in several regions outside of the HLA region, particularly on chromosomes 1p, 1q, and 18q.

Cernanec J, Guilak F, Weinberg JB, Pisetsky DS, Fermor B. · Duke University Medical Center, Durham, North Carolina 27710, USA. · Arthritis Rheum. · Pubmed #11953974 No free full text.

Abstract: OBJECTIVE: Articular cartilage is an avascular tissue that functions at a lower oxygen tension than do most tissues. With mobilization, arthritic joints may undergo cycles of hypoxia and reoxygenation. The goal of this study was to determine the effects of hypoxia and reoxygenation on cytokine-induced nitric oxide (NO) and prostaglandin E(2) (PGE(2)) production in articular cartilage. METHODS: Porcine cartilage explants were incubated at 37 degrees C for 72 hours in either 1% O(2) (hypoxia) or 20% O(2) (normoxia) in media supplemented with interleukin-1alpha (IL-1alpha) or tumor necrosis factor alpha (TNFalpha), with or without the NO synthase 2 (NOS2) selective inhibitor 1400W. Culture media were then removed and replaced with freshly prepared media and incubated for a further 24 hours in normoxia. RESULTS: NO levels were significantly higher in explants supplemented with IL-1alpha and TNFalpha compared with controls, in both hypoxia and normoxia. Compared with normoxia, hypoxia decreased IL-1alpha- and TNFalpha-induced NO production significantly. Reoxygenation of hypoxic explants resulted in sustained significant NO production in response to either cytokine. However, comparably high levels of NO production were not sustained in explants cultured continuously in normoxia. Although IL-1alpha alone did not significantly increase PGE(2) production, significant PGE(2) superinduction occurred in cartilage stimulated with IL-1alpha and the NOS2 inhibitor 1400W compared with stimulation with IL-1alpha alone in hypoxia, but not in normoxia. CONCLUSION: Oxygen tension significantly affects cytokine-induced proinflammatory mediator production in articular cartilage. Furthermore, hypoxia alters NO mediation of PGE(2) production. Hypoxia and reoxygenation can affect cytokine-induced proinflammatory mediator production, suggesting that oxygen tension may influence inflammation associated with cartilage injury and disease.

Fermor B, Weinberg JB, Pisetsky DS, Misukonis MA, Banes AJ, Guilak F. · Department of Surgery, Duke University Medical Center, Durham, NC 27710, USA. · J Orthop Res. · Pubmed #11518285 No free full text.

Abstract: Nitric oxide (NO) production and NO synthase (NOS) expression are increased in osteoarthritis and rheumatoid arthritis, suggesting that NO may play a role in the destruction of articular cartilage. To test the hypothesis that mechanical stress may increase NO production by chondrocytes, we measured the effects of physiological levels of static and intermittent compression on NOS activity, NO production, and NOS antigen expression by porcine articular cartilage explants. Static compression significantly increased NO production at 0.1 MPa stress for 24 h (P < 0.05). Intermittent compression at 0.5 Hz for 6 h followed by 18 h recovery also increased NO production and NOS activity at 1.0 MPa stress (P < 0.05). Intermittent compression at 0.5 Hz for 24 h at a magnitude of 0.1 or 0.5 MPa caused an increase in NO production and NOS activity (P < 0.05). Immunoblot analysis showed stress-induced upregulation of NOS2, but not NOS1 or NOS3. There was no loss in cell viability following any of the loading regimens. Addition of 2 mM 1400 W (a specific NOS2 inhibitor) reduced NO production by 51% with no loss of cell viability. These findings indicate that NO production by chondrocytes is influenced by mechanical compression in vitro and suggest that biomechanical factors may in part regulate NO production in vivo.

Fink C, Fermor B, Weinberg JB, Pisetsky DS, Misukonis MA, Guilak F. · Department of Surgery, Division of Orthopaedic Surgery, Duke University Medical Center, Durham, NC 27710, USA. · Osteoarthritis Cartilage. · Pubmed #11467897 No free full text.

Abstract: OBJECTIVE: The menisci play an important role in the biomechanics of the knee, and loss of meniscal function has been associated with progressive degenerative changes of the joint in rheumatoid arthritis as well as in osteoarthritis. However, little is known about the underlying mechanisms that link meniscal injury or degeneration to arthritis. Meniscal fibrochondrocytes respond to environmental mediators such as growth factors and cytokines, but the influence of mechanical stress on their metabolic activity is not well understood. Nitric oxide (NO) is believed to play a role in mechanical signal transduction, and there is also significant evidence of its role in cartilage and meniscus degeneration. The goal of this study was to determine if meniscal fibrochondrocytes respond to mechanical stress by increasing NO production in vitro. DESIGN: Explants of lateral and medial porcine menisci were dynamically compressed in a precisely controlled manner, and NO production, nitric oxide synthase antigen expression and cell viability were measured. The relative responses of the meniscal surface and deep layers to dynamic compression were also investigated separately. RESULTS: Meniscal NO production was significantly (P< 0.01) increased by dynamic compression in both the medial and lateral menisci. Dynamically compressed menisci contained inducible nitric oxide synthase antigen, while uncompressed menisci did not. Significant (P< 0.05) zonal differences were observed in basal and compression-induced NO production. DISCUSSION: Our findings provide direct evidence that dynamic mechanical stress influences the biological activity of meniscal cells. These results suggest that NO production in vivo may be in part regulated by mechanical stress acting upon the menisci. Since NO affects matrix metabolism in various intraarticular tissues, alterations in the distribution and magnitude of stress in the menisci may have important metabolic as well as biomechanical consequences on joint physiology and function.

Jawaheer D, Seldin MF, Amos CI, Chen WV, Shigeta R, Monteiro J, Kern M, Criswell LA, Albani S, Nelson JL, Clegg DO, Pope R, Schroeder HW, Bridges SL, Pisetsky DS, Ward R, Kastner DL, Wilder RL, Pincus T, Callahan LF, Flemming D, Wener MH, Gregersen PK. · Division of Biology and Human Genetics, North Shore University Hospital, Manhasset, NY 11030, USA. · Am J Hum Genet. · Pubmed #11254450 links to  free full text

Abstract: Rheumatoid arthritis (RA) is an autoimmune/inflammatory disorder with a complex genetic component. We report the first major genomewide screen of multiplex families with RA gathered in the United States. The North American Rheumatoid Arthritis Consortium, using well-defined clinical criteria, has collected 257 families containing 301 affected sibling pairs with RA. A genome screen for allele sharing was performed, using 379 microsatellite markers. A nonparametric analysis using SIBPAL confirmed linkage of the HLA locus to RA (P < .00005), with lambdaHLA = 1.79. However, the analysis also revealed a number of non-HLA loci on chromosomes 1 (D1S235), 4 (D4S1647), 12 (D12S373), 16 (D16S403), and 17 (D17S1301), with evidence for linkage at a significance level of P<.005. Analysis of X-linked markers using the MLOD method from ASPEX also suggests linkage to the telomeric marker DXS6807. Stratifying the families into white or seropositive subgroups revealed some additional markers that showed improvement in significance over the full data set. Several of the regions that showed evidence for nominal significance (P < .05) in our data set had previously been implicated in RA (D16S516 and D17S1301) or in other diseases of an autoimmune nature, including systemic lupus erythematosus (D1S235), inflammatory bowel disease (D4S1647, D5S1462, and D16S516), multiple sclerosis (D12S1052), and ankylosing spondylitis (D16S516). Therefore, genes in the HLA complex play a major role in RA susceptibility, but several other regions also contribute significantly to overall genetic risk.