Pain Mechanisms Associated With Disease Activity in Patients With Rheumatoid Arthritis Treated With Disease-Modifying Antirheumatic Drugs: A Regression Tree Analysis

Heat shock proteins in chronic pain: From molecular chaperones to pain modulators

Chronic pain is the most prevalent and complex clinical disorder,affecting approximately 30% of people globally. Various intricate alterations in nociceptive pathways responsible for chronic pain are linked to long-term tissue damage or injury to the peripheral or central nervous systems. These include remolding in the phenotype of cells and fluctuations in the expression of proteins such as ion channels, neurotransmitters, and receptors. Heat shock proteins are important molecular chaperone proteins in cell responses to stress, including inflammation, neurodegeneration, and pain signaling. They play a key role in activating glial and endothelial cells and in the production of inflammatory mediators and excitatory amino acids in both peripheral and central nervous systems. In particular, they contribute to central sensitization and hyperactivation within the dorsal horn of the spinal cord. The expression of some HSPs plays a remarkable role in upregulating pain response by acting as scavengers of ROS, controlling inflammatory cytokines. Different HSPs act by different mechanisms and several important pathways have been implicated in targeting HSPs for the treatment of neuropathic pain including p38-mitogen-activated protein kinases (MAPKs), extracellular signal-regulated kinases (ERKs), brain-derived neurotrophic factors (BDNF). We summarize the role of HSPs in various preclinical and clinical studies and the crosstalk of HSPs with various nociceptors and other pain models. We also highlighted some artificial intelligence tools and machine learning-assisted drug discovery methods for rapid screening of HSPs in various diseases. Focusing on HSPs could lead to the development of new therapeutics that modulate pain responses and enhance our understanding of pain in various pathological conditions and neurological disorders.

Trajectories of self-reported pain-related health outcomes and longitudinal effects on medication use in rheumatoid arthritis: a prospective cohort analysis using the Australian Rheumatology Association Database (ARAD)

OBJECTIVE

To determine distinct trajectories of self-reported pain-related health status in rheumatoid arthritis (RA), their relationship with sociodemographic factors and medication use.

METHODS

988 Australian Rheumatology Association Database participants with RA (71% female, mean age 54 years, mean disease duration 2.3 years) were included. Distinct multi-trajectories over 15-year follow-up for five different self-reported pain-related health outcome measures (Health Assessment Questionnaire Disability Index, visual analogue scores for pain, arthritis, global health and the Assessment of Quality of Life utility index) were identified using latent variable discrete mixture modelling. Random effects models were used to determine associations with medication use and biologic therapy modification during follow-up.

RESULTS

Four, approximately equally sized, pain/health status groups were identified, ranging from 'better' to 'poorer', within which changes over time were relatively small. Important determinants of those with poorer pain/health status included female gender, obesity, smoking, socioeconomic indicators and comorbidities. While biologic therapy use was similar between groups during follow-up, biologic therapy modifications (p_linear<0.001) and greater tendency of non-tumour necrosis factor inhibitor use (p_linear<0.001) were observed in those with poorer pain/health status. Similarly, greater use of opioids, prednisolone and non-steroidal anti-inflammatory drugs was seen in those with poorer pain/health status.

CONCLUSION

In the absence of disease activity information, distinct trajectories of varying pain/health status were seen from the outset and throughout the disease course in this RA cohort. More biologic therapy modifications and greater use in anti-inflammatories, opioids and prednisolone were seen in those with poorer pain/health status, reflecting undesirable lived experience of persistent pain in RA.