Pain management in patients with rheumatoid arthritis

Current status and influencing factors of fatigue in patients with rheumatoid arthritis: A cross-sectional study in China

AIM

This study aimed to explore the level and influencing factors of fatigue in patients with rheumatoid arthritis.

METHODS

This cross-sectional study was conducted in 243 patients with rheumatoid arthritis from April 2016 to March 2017. The Bristol Rheumatoid Arthritis Fatigue Multi-Dimensional Questionnaire, Arthritis Self-Efficacy Scale-8, Visual Analogue Scale for pain, physical function subscale of Short Form 36-Item Health Survey, Hospital Anxiety and Depression Scale, Perceived Social Support Scale, Pittsburgh Sleep Quality Index and a self-designed demographic and disease-related information questionnaire were used to collect the data. Stepwise linear multiple regression was used to clarify the impact of statistically significant variables (P < 0.05) in the independent sample t test, one-way ANOVA and correlation analysis on the level of fatigue.

RESULTS

Stepwise linear multiple regression analyses showed that disease activity, self-efficacy, physical function, pain, depression, duration of morning stiffness and anxiety were major factors influencing fatigue in patients with rheumatoid arthritis, which explained 59.5% of the total variance.

CONCLUSION

Our study demonstrated a moderate level of fatigue in Chinese patients with rheumatoid arthritis. In clinical practice, nurses should explore individualized intervention programmes based on related predictors of fatigue to help patients relieve fatigue.

Neuronal FcγRI mediates acute and chronic joint pain

Although joint pain in rheumatoid arthritis (RA) is conventionally thought to result from inflammation, arthritis pain and joint inflammation are at least partially uncoupled. This suggests that additional pain mechanisms in RA remain to be explored. Here we show that FcγRI, an immune receptor for IgG immune complex (IgG-IC), is expressed in a subpopulation of joint sensory neurons and that, under naïve conditions, FcγRI crosslinking by IgG-IC directly activates the somata and peripheral terminals of these neurons to evoke acute joint hypernociception without obvious concurrent joint inflammation. These effects were diminished in both global and sensory neuron-specific Fcgr1 knockout mice. In murine models of inflammatory arthritis, FcγRI signaling was upregulated in joint sensory neurons. Acute blockade or global genetic deletion of Fcgr1 significantly attenuated arthritis pain and hyperactivity of joint sensory neurons without measurably altering joint inflammation. Conditional deletion of Fcgr1 in sensory neurons produced similar analgesic effects in these models. We therefore suggest that FcγRI expressed in sensory neurons contributes to arthritis pain independently of its functions in inflammatory cells. These findings expand our understanding of the immunosensory capabilities of sensory neurons and imply that neuronal FcγRI merits consideration as a target for treating RA pain.

Gabapentin regulates expression of FGF2 and FGFR1 in dorsal root ganglia via microRNA-15a in the arthritis rat model

BACKGROUND

Arthritis is an inflammatory disease with a prevalence rate of approximately 10% in China, which commonly manifests as pain. The aim of the current study was to investigate the function of gabapentin in the dorsal root ganglion in an arthritis rat model, and assess the effect of gabapentin on the expression of fibroblast growth factor 2 (FGF2) and FGF receptor 1 (FGFR1).

METHODS

A total of 30 healthy male Sprague-Dawley rats were randomly divided into the following three groups: Untreated group, control group and gabapentin group. Rats in the control and the gabapentin groups were injected with Freund's complete adjuvant to induce arthritis. A total of 7 days subsequent to model establishment, the gabapentin group was administered intraperitoneally gabapentin for 8 days. The alterations in thickness of paw pad and paw withdrawal mechanical threshold (PWMT) were detected, which indicated that the rats in the control and gabapentin groups presented with the symptoms of arthritis.

RESULTS

In the control group, the PWMT value was significantly reduced (P < 0.05), whereas the PWMT value was significantly increased in the gabapentin group. Immunohistochemistry demonstrated that the expression levels of FGF2 and FGFR1 were increased in the control group compared with the untreated group, while the expression levels of FGF2 and FGFR1 were reduced in the gabapentin group. Moreover, the FGF2 antagonist PD173074 partially improved the plantar thickness and PWMT of the arthritic rats. Bioinformatics analysis predicted microRNA-15a binding sites in the 3'untranslated regions (UTR) of FGF2 and FGFR1. Furthermore, the expression of microRNA-15a was reduced in the control group compared with untreated rats, whereas microRNA-15a in the gabapentin group was upregulated compared with the control. Additionally, the luciferase reporter assay confirmed that microRNA-15a could inhibit the protein expression through pairing with the 3'UTR of FGF2 and FGFR1 mRNAs.

CONCLUSION

Gabapentin may relieve arthritis pain and reduce the expression of FGF2 and FGFR1 in dorsal root ganglia. Furthermore, microRNA-15a may be involved in the regulatory process.

Are Foot and Ankle Characteristics Associated With Falls in People With Rheumatoid Arthritis? A Prospective Study

OBJECTIVE

To determine whether foot and ankle characteristics are associated with falls in people with rheumatoid arthritis (RA).

METHODS

A total of 201 adults with RA were recruited from rheumatology outpatient clinics in Auckland, New Zealand. Clinical characteristics, common fall risk factors, and foot and ankle variables were measured. Participants were prospectively studied for 12 months to record the occurrence of falls using falls diaries. Logistic regression analysis identified baseline variables that were independent predictors of falls over the 12 months.

RESULTS

Eighty-four participants (42%) fell at least once and 39 (19%) experienced multiple (>1) falls over the 12-month followup period. In logistic regression analysis, including age and significant baseline variables in bivariate analysis but not baseline fall history, presence of foot or ankle tender joints (odds ratio [OR] 1.95, P = 0.034) and psychotropic medication (OR 2.35, P = 0.025) were independent predictors of prospective falls. However, when baseline fall history was included in the analysis, psychotropic medication (OR 2.34, P = 0.025) and baseline fall history (over the preceding 12 months) (OR 2.27, P = 0.008) were independent predictors of prospective falls.

CONCLUSION

Foot and ankle characteristics are not associated with falls in people with RA, independent of prior falls. Inquiry about prior falls and psychotropic medications may assist in identifying patients with RA who are at high risk of future falls.

Effects of Koumine on Adjuvant- and Collagen-Induced Arthritis in Rats

To examine the effect of koumine, a Gelsemium alkaloid, on two experimental models of rheumatoid arthritis (RA), rats with adjuvant-induced arthritis (AIA) and collagen-induced arthritis (CIA) were administered koumine (0.6, 3, or 15 mg/kg/day) or vehicle through gastric gavage (i.g.). Clinical evaluation was performed via measurements of hind paw volume, arthritis index (AI) score, mechanical withdrawal threshold, organ weight, and by radiographic and histological examinations. Levels of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and antitype II collagen (CII) antibody were also examined. In rats with AIA, koumine reduced the AI score and mechanical allodynia of the injected hind paw in a dose-dependent manner and significantly inhibited increase in thymus and liver weights. In rats with CIA, koumine inhibited increase in hind paw volume, AI score, and mechanical allodynia in a dose-dependent manner and reduced joint space narrowing. Furthermore, koumine also attenuated the increase in the expression of IL-1β and TNF-α, as well as the robust increase of serum anti-CII antibodies in response to immunization. These results suggested that koumine effectively attenuated arthritis progression in two rat models of RA and that this therapeutic effect may be associated with its immunoregulatory action.

Pain in rheumatoid arthritis: models and mechanisms

Pain is one of the most challenging symptoms for patients with rheumatoid arthritis (RA). RA-related pain is frequently considered to be solely a consequence of inflammation in the joints; however, recent studies show that multiple mechanisms are involved. Indeed, RA pain may start even before the disease manifests, and frequently does not correlate with the degree of inflammation or pharmacological management. In this aspect, animal studies have the potential to provide new insights into the pathology that initiate and maintain pain in RA. The focus of this review is to describe the most commonly used animal models for studies of RA pathology, which have also been utilized in pain research, and to summarize findings providing potential clues to the mechanisms involved in the regulation of RA-induced pain.

β2-adrenoceptor signaling reduction in dendritic cells is involved in the inflammatory response in adjuvant-induced arthritic rats

Rheumatoid arthritis (RA) is characterized by inflammation of the synovium, which leads to the progressive destruction of cartilage and bone. Adrenoreceptor (AR) signaling may play an important role in modulating dendritic cell (DC), which may be involved in the pathogenesis of RA. We examined the effect of the β-AR agonist isoprenaline (ISO) on DC function, the impact of the β₂-AR agonist salbutamol on adjuvant-induced arthritic (AA) rats, and changes in β₂-AR signaling in DCs during the course of AA. ISO inhibited the expression of the surface molecules CD86 and MHC-II, inhibited the stimulation of T lymphocyte proliferation by DC and TNF-α secretion, and promoted DC antigen uptake and IL-10 secretion. The effects of ISO on MHC-II expression, DC stimulation of T lymphocyte proliferation, and DC antigen uptake were mediated by β₂-AR. Treatment with salbutamol ameliorated the severity of AA and histopathology of the joints and inhibited proliferation of thymus lymphocytes and FLS in vivo. β₂-AR signaling was weaker in AA rats compared to the control. Elevated GRK2 and decreased β₂-AR expression in DC cytomembranes were observed in AA and may have decreased the anti-inflammatory effect of β₂-AR signaling. Decreased β₂-AR signaling may be relevant to the exacerbation of arthritis inflammation.