The major pain source of rotator cuff-related shoulder pain: A narrative review on current evidence

BACKGROUND

Rotator cuff-related shoulder pain (RCRSP) was proposed to have a complex pain mechanism, but the exact aetiology is still unclear. A recent review summarised the updated research to analyse the traditional concept of shoulder impingement which may not be accurate. Current studies have demonstrated that mechanical factors including a reduction in subacromial space, scapular dyskinesia and different acromial shapes are unlikely directly contributing to RCRSP.

AIMS

Since the precise RCRSP pain mechanism remains unclear, the aim of this narrative review is to discuss possible sources of pain contributing to RCRSP according to the mechanisms-based pain classifications.

RESULTS AND DISCUSSION

Research findings on potential mechanical nociceptive factors of RCRSP are conflicting; investigations of neuropathic and central pain mechanisms of RCRSP are limited and inconclusive. Overall, available evidence has indicated moderate to strong correlations between RCRSP and chemical nociceptive sources of pain.

CONCLUSION

Results from current research may provide new directions for future studies on the aetiology of RCRSP and its clinical management towards a biochemical view instead of the traditional mechanical hypothesis.

Anaphylatoxin Complement 5a in Pfizer BNT162b2-Induced Immediate-Type Vaccine Hypersensitivity Reactions

The underlying immunological mechanisms of immediate-type hypersensitivity reactions (HSR) to COVID-19 vaccines are poorly understood. We investigate the mechanisms of immediate-type hypersensitivity reactions to the Pfizer BNT162b2 vaccine and the response of antibodies to the polyethylene glycol (PEG)ylated lipid nanoparticle after two doses of vaccination. Sixty-seven participants, median age 35 and 77.3% females who tolerated two doses of the BNT162b2 vaccine (non-reactors), were subjected to various blood-sampling time points. A separate group of vaccine reactors (10 anaphylaxis and 37 anonymised tryptase samples) were recruited for blood sampling. Immunoglobulin (Ig)G, IgM and IgE antibodies to the BNT162b2 vaccine, biomarkers associated with allergic reaction, including tryptase for anaphylaxis, complement 5a(C5a), intercellular adhesion molecule 1 (ICAM-1) for endothelial activation and Interleukin (IL)-4, IL-10, IL-33, tumour necrosis factor (TNF) and monocyte chemoattractant protein (MCP-1), were measured. Basophil activation test (BAT) was performed in BNT162b2-induced anaphylaxis patients by flow cytometry. The majority of patients with immediate-type BNT162b2 vaccine HSR demonstrated raised C5a and Th2-related cytokines but normal tryptase levels during the acute reaction, together with significantly higher levels of IgM antibodies to the BNT162b2 vaccine (IgM 67.2 (median) vs. 23.9 AU/mL, p < 0.001) and ICAM-1 when compared to non-reactor controls. No detectable IgE antibodies to the BNT162b2 vaccine were found in these patients. The basophil activation tests by flow cytometry to the Pfizer vaccine, 1,2-dimyristoyl-rac-glycero-3-methoxypolyethylene glycol (DMG-PEG) and PEG-2000 were negative in four anaphylaxis patients. Acute hypersensitivity reactions post BNT162b2 vaccination suggest pseudo-allergic reactions via the activation of anaphylatoxins C5a and are independent of IgE-mechanisms. Vaccine reactors have significantly higher levels of anti-BNT162b2 IgM although its precise role remains unclear.

Immune and coagulation profiles in 3 adults with multisystem inflammatory syndrome

Introduction: There is a paucity of information on the cytokine, complement, endothelial activation, and coagulation profiles of multisystem inflammatory syndrome in adults (MIS-A), a rare but serious complication following recovery from SARS-CoV-2 infection. We aim to examine the immune biomarker and coagulation profiles in association with the clinical presentation and course of MIS-A. Method: The clinical features of MIS-A patients admitted to our tertiary hospital were documented. Their levels of interleukin (IL)-1β, IL-6, IL-10, IL-17, IL-18, interferon-α (IFN-α), IFN-γ, interferon gamma-induced protein 10 (IP-10), tumour necrosis factor (TNF)-α, monocyte chemoattractant protein (MCP)-1, complement activation product (complement 5a [C5a]), and endothelial biomarker intercellular adhesion molecule-1 (ICAM-1) levels were assayed. The haemostatic profile was assessed with standard coagulation testing and thromboelastography. Results: Three male patients were diagnosed with MIS-A at our centre from January to June 2022 with a median age of 55 years. All had tested positive for SARS-CoV-2 12–62 days prior to MIS-A presentation, with gastrointestinal and cardiovascular systems as the most commonly involved. Levels of IL-6, IL-10, IL-18, IP-10 and MCP-1 were raised whereas IL-1β, IFN-α, IFN-γ, IL-17 and TNF-α remained normal. Markedly elevated levels of C-reactive protein (CRP), ferritin and ICAM-1 were present in all. C5a was elevated in 2 patients. A hypercoagulable state was demonstrated by raised levels of D-dimer, factor VIII, von Willebrand factor antigen, and ristocetin cofactor with corresponding raised parameters in thromboelastography in the 2 patients who had their coagulation profile assessed. Conclusion: MIS-A patients demonstrate activation of pro-inflammatory cytokines, endotheliopathy, complement hyperactivation and hypercoagulability. Keywords: COVID-19, cytokines, hypercoagulability, hyperinflammatory syndrome

Anti-Cytokine Autoantibodies in Systemic Lupus Erythematosus

Cytokine dysregulation is characteristic of systemic lupus erythematosus (SLE), a systemic autoimmune disease of considerable heterogeneity. Insights gained about the cytokine dysregulation in SLE have the potential for identifying patient subsets before the onset of clinical disease and during established disease. Clustering patients by cytokine and disease activity subsets is more informative than isolated cytokine studies, as both pro inflammatory and immunoregulatory cytokines contribute to the cytokine dysregulated state in SLE. Endogenous anti-cytokine autoantibodies (ACAAs) may be involved in the regulation of cytokine biology by reducing excessive production or by prolonging their half-life in the circulation through the formation of cytokine-antibody immune complexes. Although endogenous ACAAs may have deleterious effects such as contributing to immunodeficiency states, their role in the pathophysiology of autoimmune conditions such as SLE has yet to be clearly elucidated. The aim of the present article is to provide a focused review of the current knowledge of ACAAs in SLE.

A brief report on the clinical trial on neural mobilization exercise for joint pain in patients with rheumatoid arthritis

BACKGROUND

In rheumatoid arthritis (RA) synovitis, activation of synoviocytes and infiltration of adaptive immune cells leads to synovial hyperplasia and joint swelling. Under the elevated extra-neural pressure, free nerve endings release neuropeptides, calcitonin gene-related peptide, and substance P, thus promoting neurogenic inflammation.

OBJECTIVE

This study aimed to assess the effect of therapeutic neural mobilization (NM) exercises targeting the nervous system on disease impact in RA patients.

METHODS

A total of 21 RA patients were randomized into NM (n = 11) and control (n = 10) groups. NM group patients performed NM exercises targeting the median, musculocutaneous, femoral, and saphenous nerve, as well as the entire nervous system twice daily for 4-8 weeks. Control RA patients performed gentle joint mobilization exercises targeting the same joints. Primary outcome was the change in pre-/post-treatment score in the validated Rheumatoid Arthritis Impact of Disease (RAID). Secondary outcome was erythrocyte sedimentation rate (ESR).

RESULTS

There were no significant differences between the groups at baseline. No adverse events were observed and compliance was over 90%. Post-treatment, favorable changes were observed in the NM group RAID score: -5.1 vs. -0.8; weighted RAID score: -0.79 vs. -0.15. ESR was reduced in the NM group, albeit non-significantly. Regarding the RAID score domains, the NM group demonstrated significant improvements in pain and coping.

CONCLUSION

The current data indicate a beneficial effect of NM exercises on pain and self-efficacy in our RA patients. Larger clinical studies are warranted to determine the clinical effectiveness of NM as a treatment for pain for RA patients and simultaneously address immune and neuropeptide modulation through NM.