A short-term pharmacodynamic model for monitoring aggrecanase activity: injection of monosodium iodoacetate (MIA) in rats and assessment of aggrecan neoepitope release in synovial fluid using novel ELISAs.

OBJECTIVE: To develop a short-term in vivo model in rats, with an enzyme-linked immunosorbent assay (ELISA) readout for specific aggrecanase-cleaved aggrecan fragments, to facilitate testing of aggrecanase inhibitors. METHODS: Monosodium iodoacetate (MIA), a metabolic inhibitor, was injected into the right knee joint of male Lewis rats and the release of aggrecanase-cleaved fragments of aggrecan containing the NITEGE or ARGN neoepitope was measured in the synovial fluid at 7 days post MIA injection using novel ELISAs. The ELISAs utilize a commercial antibody directed against the hyaluronic-acid binding region (HABR) of aggrecan, in combination with either an alpha-NITEGE antibody (NITEGE ELISA) or an alpha-ARGS/BC3 antibody (ARGS ELISA), to detect aggrecanase-cleavage of aggrecan within the interglobular domain (IGD). Aggrecan fragments present in in vitro digests, in cytokine-treated cartilage explant culture supernatants and in rat synovial fluid lavage samples were detected and quantified using the two ELISAs. Small molecule inhibitors of aggrecanase activity were dosed orally on days 3-7 to determine their ability to inhibit MIA-induced generation of the NITEGE and ARGN neoepitopes measured in the rat synovial fluid. RESULTS: The NITEGE assay was shown to specifically detect the N-terminal fragment of aggrecan comprising the G1 domain and the NITEGE neoepitope sequence. This assay can readily measure aggrecanase-cleaved bovine, human and rat aggrecan without the need for deglycosylation. The ARGS assay specifically detects C-terminal fragments of aggrecan comprising the ARGS/ARGN neoepitope and the G2 domain. Keratan sulfate (KS) residues of aggrecan interfere with this ELISA, and hence this assay works well with native rat articular cartilage aggrecan (that lacks KS residues) and with deglycosylated bovine and human aggrecan. Injection of MIA into the rat knee joints resulted in a time-dependent increase in the release of aggrecanase-cleaved aggrecan fragments into the synovial fluid and treatment with an aggrecanase inhibitor resulted in a dose-dependent inhibition of the generation of these neoepitopes. CONCLUSIONS: We have established a short-term in vivo model in rats that involves measurement of synovial fluid biomarkers that are dependent on aggrecanase activity in the joint. The short duration of the model combined with the mechanistic biomarker readout makes it very useful for the initial in vivo screening of aggrecanase inhibitors prior to testing them in time and resource-intensive disease models of osteoarthritis (OA).

A proposed approach to recognise "near-remission" quantitatively without formal joint counts or laboratory tests: a patient self-report questionnaire routine assessment of patient index data (RAPID) score as a guide to a "continuous quality improvement" s.

A proposed approach is presented to recognise a status of "near-remission" in a patient with rheumatoid arthritis (RA) on the basis of patient self-report questionnaire data without formal joint counts or laboratory tests. Indices of patient-reported outcome (PRO) measures distinguish active from control treatments in RA clinical trials at levels similar to American College of Rheumatology (ACR) or disease activity score (DAS) 28 improvement levels. PRO measures on a multidimensional health assessment questionnaire (MDHAQ) can be compiled into a routine assessment of patient index data (RAPID) score. RAPID 3 includes the three PRO measures from the ACR Core Data Set - physical function, pain, and global estimate. RAPID 4 adds a self-report joint count from a rheumatoid arthritis disease activity index (RADAI). RAPID 5 adds a physician estimate of global status. RAPID cores may be classified into four preliminary proposed categories, as "near-remission" (0-1), "low severity" (1.01-2), "moderate severity" (2.01-4), and "high severity" (> 4), analogous to the four categories of the DAS28 of "remission" (< 2.6), as well as "low" (2.6-3.19), "moderate" (3.2-5.1), and "high" (> 5.1) disease activity. RAPID scores are correlated significantly with DAS28 (rho = 0.64-0.67, p < 0.001), and about 75% of patients with DAS < 2.6 have RAPID scores < 2, while about 75% of patients with DAS > 5.1 have RAPID scores > 4. RAPID data are available on one side of one page, and are feasible to collect in standard clinical care. RAPID 3 scores may be calculated in about 10 seconds, and RAPID 4 and RAPID 5 scores in 20 to 30 seconds. RAPID scores every 3 months or more on simple flowsheets can be a basis for a "continuous quality improvement" strategy in standard clinical care to recognise a need for aggressive therapy, an inadequate response to a therapy, and "near- remission" status.

Toward a multidimensional Health Assessment Questionnaire (MDHAQ): assessment of advanced activities of daily living and psychological status in the patient-friendly health assessment questionnaire format.

OBJECTIVE: To develop components of a multidimensional Health Assessment Questionnaire (MDHAQ) through the addition of new items in the "patient-friendly" HAQ format, including advanced activities of daily living (ADL), designed to overcome "floor effects" of the HAQ and modified HAQ (MHAQ) in which patients may report normal scores although they experience meaningful functional limitations, and psychological items, designed to screen efficiently for psychological distress in routine care. METHODS: The new MDHAQ items, as well as scales for pain, fatigue, helplessness, and global health status on a 2-page questionnaire, were completed by 688 consecutive patients with various rheumatic diseases, including 162 with rheumatoid arthritis (RA), 114 with fibromyalgia, 63 with osteoarthritis, 34 with systemic lupus erythematosus, 20 with vasculitis, 18 with psoriatic arthritis, 16 with scleroderma, and 261 with various other rheumatic diseases, over 2 years at a weekly academic rheumatology clinic. RESULTS: The new MDHAQ items have good test-retest reliability and face validity. MHAQ scores were highest in patients with RA, and scores for other scales were highest in patients with fibromyalgia. On the advanced ADL, 58% of patients reported difficulty with errands, 68% with climbing stairs, 79% with walking two miles, 87% with participating in sports and games, and 94% with running or jogging two miles. On the psychological items, 75% of patients reported difficulty with sleep, 63% with stress, 61% with anxiety, and 57% with depression. Normal MHAQ scores were reported by 23% of patients and normal HAQ scores by 16% of patients who completed these questionnaires, while fewer than 5% had normal scores on the MDHAQ. CONCLUSION: The MDHAQ items overcome in large part the "floor effects" seen on the HAQ and MHAQ, and are useful to screen for problems with sleep, stress, anxiety, and depression in the "patient-friendly" HAQ format. These data support the value of completion of a simple 2-page patient questionnaire by each patient at each visit to a rheumatologist.