Heavy Chain Constant Region Usage in Antibodies to Peptidylarginine Deiminase 4 as a Marker of Disease Subsets in Rheumatoid Arthritis

OBJECTIVE

The study of autoantibody isotypes in autoimmune diseases is useful for identifying clinically relevant endotypes. This study was undertaken to study the prevalence and clinical significance of different isotypes and IgG subclasses of anti-peptidylarginine deiminase 4 (anti-PAD4) autoantibodies in individuals with rheumatoid arthritis (RA).

METHODS

In 196 RA subjects and 64 healthy controls, anti-PAD4 antibody types were determined using enzyme-linked immunosorbent assay. We investigated associations between anti-PAD4 antibodies and clinical outcomes, and relevant features were confirmed in an independent RA cohort.

RESULTS

Anti-PAD4 IgG1, anti-PAD4 IgG2, anti-PAD4 IgG3, anti-PAD4 IgG4, anti-PAD4 IgA, and anti-PAD4 IgE antibodies were more frequent in RA patients than healthy controls (P < 0.001). Anti-PAD4 IgG1, anti-PAD4 IgG3, and anti-PAD4 IgE were associated with distinct clinical features. Anti-PAD4 IgG1 was predictive of progressive radiographic joint damage (odds ratio [OR] 4.88, P = 0.005), especially in RA patients without baseline joint damage (40% versus 0%, P = 0.003) or in those negative for anti-cyclic citrullinated peptide and/or rheumatoid factor (OR 32; P = 0.009). IgG1 was also associated with higher levels of C-reactive protein (P = 0.006) and interleukin-6 (P = 0.021). RA patients with anti-PAD4 IgG3 had higher baseline joint damage scores (median Sharp/van der Heijde score 13 versus 7, P = 0.046), while those with anti-PAD4 IgE had higher Disease Activity Score in 28 joints (median 4.0 versus 3.5, P = 0.025), more frequent rheumatoid nodules (31% versus 16%, P = 0.025), and more frequent interstitial lung disease (ground-glass opacification) (24% versus 9%, P = 0.014). Anti-PAD4 IgG1 antibody associations with joint damage were corroborated in an independent RA cohort.

CONCLUSION

Anti-PAD4 IgG1, anti-PAD4 IgG3, and anti-PAD4 IgE antibodies identify discrete disease subsets in RA, suggesting that heavy chain usage drives distinct effector mechanisms of anti-PAD4 antibodies in RA.

Citrullination of myofilament proteins in heart failure

AIMS

Citrullination, the post-translational conversion of arginine to citrulline by the enzyme family of peptidylarginine deiminases (PADs), is associated with several diseases, and specific citrullinated proteins have been shown to alter function while others act as auto-antigens. In this study, we identified citrullinated proteins in human myocardial samples, from healthy and heart failure patients, and determined several potential functional consequences. Further we investigated PAD isoform cell-specific expression in the heart.

METHODS AND RESULTS

A citrullination-targeted proteomic strategy using data-independent (SWATH) acquisition method was used to identify the modified cardiac proteins. Citrullinated-induced sarcomeric proteins were validated using two-dimensional gel electrophoresis and investigated using biochemical and functional assays. Myocardial PAD isoforms were confirmed by RT-PCR with PAD2 being the major isoform in myocytes. In total, 304 citrullinated sites were identified that map to 145 proteins among the three study groups: normal, ischaemia, and dilated cardiomyopathy. Citrullination of myosin (using HMM fragment) decreased its intrinsic ATPase activity and inhibited the acto-HMM-ATPase activity. Citrullinated TM resulted in stronger F-actin binding and inhibited the acto-HMM-ATPase activity. Citrullinated TnI did not alter the binding to F-actin or acto-HMM-ATPase activity. Overall, citrullination of sarcomeric proteins caused a decrease in Ca(2+) sensitivity in skinned cardiomyocytes, with no change in maximal calcium-activated force or hill coefficient.

CONCLUSION

Citrullination unique to the cardiac proteome was identified. Our data indicate important structural and functional alterations to the cardiac sarcomere and the contribution of protein citrullination to this process.

Role of coenzyme Q10 in chronic heart failure, angina, and hypertension

PURPOSE

Coenzyme Q10 (CoQ10) has a pathophysiologic role in many disease states. The purpose of this review is to provide recommendations regarding the safety, efficacy, and dosing of CoQ10 in the management of chronic heart failure (CHF), angina, and hypertension.

DATA SOURCES

Literature pertaining to the safety and efficacy of CoQ10 specifically in cardiovascular indications was reviewed. We used relevant clinical trials, articles, reviews, and letters that were selected from a literature search of the MEDLINE database (1974-2000), Micromedex Healthcare Series, and the Natural Medicines Comprehensive Database.

FINDINGS

Coenzyme Q10 administered orally has favorable actions in the described cardiovascular conditions and appears to be safe and well tolerated in the adult population. Issues concerning optimum target dosages, potential interactions, monitoring parameters, and the role of CoQ10 as a monotherapeutic agent need to be investigated further. Favorable effects of CoQ10 on ejection fraction, exercise tolerance, cardiac output, and stroke volume are demonstrated in the literature; thus, the use of CoQ10 as adjuvant therapy in patients with CHF may be supported.

CONCLUSIONS

Coenzyme Q10 therapy in angina and hypertension cannot be substantiated until additional clinical trials demonstrate consistent beneficial effects. However, CoQ10 may be recommended as adjuvant therapy in selected patients with CHE At this time, CoQ10 should not be recommended as monotherapy or first-line therapy in any disease state.

Results of a community pharmacy-based breast cancer risk-assessment and education program

We tested the hypothesis that an education program addressing breast cancer screening schedules and modalities coupled with a breast cancer risk assessment provided by community pharmacists can increase women's confidence in performing screening practices endorsed by the American Cancer Society (ACS). This randomized, paired, pre-post study was conducted in six community pharmacies and two health-screening fairs; subjects were 140 women over 18 years of age. The pharmacist-administered program used the Breast Cancer Risk-Assessment Tool (Gail model) software provided by the National Cancer Institute of the National Institutes of Health. In addition, pharmacists provided education and training on breast self-examination (BSE), clinical breast examination (CBE), and mammography. Adherence to ACS guidelines for monthly BSE increased from 31% to 56% (p<0.001) for all women 6 months after the program. Performance of monthly BSE by women considered at high risk for developing breast cancer increased from 20% to 60% (p<0.005). The mean number of BSEs performed over 6 months increased from 2.69 to 4.09 (p<0.001). Women's confidence performing correct BSE improved from 6.41 to 7.04 (p<0.001) on a scale of 0-10. Adherence to ACS guidelines for CBE and mammography did not reveal statistically significant improvements except for better adherence to CBE in women aged 40-49 years (81% to 97%, p<0.025). The strength of the pharmacists' intervention may not appear as manipulation of high-risk patients' behavior but as improvement of self-directed behaviors, such as BSE, across all age groups.

Evaluation of echinacea for treatment of the common cold

Considered to have immunostimulating activity, echinacea is a widely used phytomedicinal for treatment of the common cold and upper respiratory tract infections (URTIs). We reviewed the literature from the MEDLINE database (January 1966-July 1999), International Pharmaceutical Abstracts (IPA) online database, Cambridge Scientific Abstracts Biological Sciences online database, Alt-Health Watch online database, EMBase CD-ROM database, and references from published articles, reviews, and letters to evaluate evidence from clinical trials of echinacea's purported efficacy for treating or preventing URTIs. Twelve clinical studies published from 1961-1997 concluded that echinacea was efficacious for treating the common cold, but the results are unclear due to inherent flaws in study design. Five trials were published since 1997; two showed that echinacea lacked efficacy for treating and preventing URTI symptoms, and three concluded that it was effective in reducing the frequency, duration, and severity of common cold symptoms. Again, these results are unclear because of methodologic uncertainties, such as small populations and use of noncommercially available, nonstandardized dosage forms. Although evidence for echinacea's efficacy is inconclusive, it appears to be safe. Patients without contraindications to it may not be dissuaded from using an appropriate preparation to treat the common cold.