Rheumatoid arthritis (RA) and adult periodontitis share common pathogenetic mechanisms and immunologic and pathological findings. One oral pathogen strongly implicated in the pathogenesis of periodontal disease, Porphyromonas gingivalis, possesses a unique microbial enzyme, peptidylarginine deiminase (PAD), the human equivalent of which has been identified as a susceptibility factor for RA. We suggest that individuals predisposed to periodontal infection are exposed to antigens generated by PAD, with de-iminated fibrin as a likely candidate, which become systemic immunogens and lead to intraarticular inflammation. PAD engendered antigens lead to production of rheumatoid factor-containing immune complexes and provoke local inflammation, both in gingiva and synovium via Fc and C5a receptors.

The aim of this review is to analyze the available literature regarding the neuropsychiatric (NP) disturbances associated with corticosteroid (CS) therapy; to determine the nature, severity, and frequency of these NP symptoms; and to identify the various risk factors involved in the development of CS-induced NP disturbances. We searched the available literature since the advent of corticosteroid therapy (1950) utilizing the PubMed database ( www.pubmed.gov). Primary articles were identified, and they and their pertinent references were reviewed. Due to potential confusion between NP manifestations of CS therapy and central nervous system (CNS) involvement of systemic lupus erythematosus (SLE), a condition often treated with CS, a brief review of NP manifestations of SLE was also performed. The presentation of CS-induced neuropsychiatric disorders (CIPD) can be quite varied with depression, hypomania, and overt psychosis being the most common manifestations. CIPD can also include bipolar affective changes, delirium, panic attacks, agoraphobia, obsessive-compulsive disorder, anxiety, insomnia, restlessness, fatigue, catatonia, reversible dementia-like cognitive changes, impaired memory, and concentration. No factors have been identified that allow for the accurate prediction of development of CIPD. A dose-dependent relationship (increased risk when the daily prednisone-equivalent dose is ≥40 mg) has been observed in most cases of CIPD, although there have been case reports with lower doses, alternate-day therapy, and even inhaled CS. Women are more commonly affected with most symptoms occurring in the first 6 weeks of starting treatment. SLE has been the only specific illness that has been linked to a greater risk of CIPD and the NP manifestations of SLE may mimic those of CIPD, with most occurring in the first year of diagnosis. Antiribosomal P, antineuronal, or antiphospholipid antibodies are frequently seen in patients with SLE developing CIPD. Imaging and EEG abnormalities, the coexistence of non-CNS manifestations of SLE, and the presence of serious disturbances in memory and concentration are more suggestive of NP-SLE than CIPD. Although NP symptoms associated with the use of CS generally resolve with discontinuation of the medication, prophylaxis with lithium, and treatment with antidepressants, anticonvulsants and electroconvulsive therapy for severe mania and depression have been reported with successful outcomes. A greater understanding of the underlying mechanism of CIPD, risk factors involved, treatment options, and the distinguishing features from NP-SLE will ultimately lead to more directed therapy for such patients.

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To examine the relative influence of speed of information processing versus working memory ability, CFS participants with psychiatric comorbidity (CFS-Psych) and CFS without a psychiatric history (CFS-noPsych) were examined on tests of visual and auditory processing speed and visual and auditory working memory. Compared to healthy controls (HC) and a group of participants with rheumatoid arthritis (RA), the CFS-noPsych group displayed significantly reduced performance on tests of information processing speed, but not on tests of working memory. No significant differences were observed between the CFS-Psych group and any other group in the study. The implications of group heterogeneity on the understanding of cognitive impairment in CFS are discussed.

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We have recently demonstrated that adenosine, acting via adenosine A2 receptors, inhibits generation of superoxide anions (O2-) by stimulated neutrophils. To determine the mechanism(s) by which adenosine inhibits O2- generation stimulated by the chemoattractant N-formylmethionylleucylphenylalanine (FMLP), we examined cyclic AMP (cAMP) concentrations, stimulated membrane depolarization and Ca2+ movements. Neither adenosine nor 5'-N-ethylcarboxamidoadenosine (NECA), the most potent agonist at adenosine A2 receptors, increases neutrophil cAMP content. However in the presence of the non-methylxanthine phosphodiesterase inhibitor, Ro-20-1724, both adenosine and NECA elicit a reversible increase in intracellular cAMP concentration. The chemoattractant FMLP also elicits an increment in the neutrophil cAMP content. NECA, in the presence of Ro-20-1724, synergistically enhances the increment in cAMP following stimulation by FMLP. However Ro-20-1724 does not potentiate the inhibition of O2- generation by NECA. Unlike other agents which increase neutrophil cAMP concentrations, NECA, even in the presence of a phosphodiesterase inhibitor, only trivially inhibits degranulation. We also found that adenosine markedly inhibits stimulated membrane depolarization but does not affect the stimulated increment in free ionized intracellular calcium. Moreover, inhibition by adenosine of O2- generation does not vary with the concentration of extracellular calcium. These results fulfil the last criterion for the demonstration of an A2 receptor on human neutrophils, and indicate that adenosine occupies an A2 receptor on neutrophils to raise intracellular cAMP in synergy with occupancy of the FMLP receptor. The results reported here also indicate that cAMP is not the second messenger for inhibition of O2- generation by adenosine and its analogues.