Modeling environmental inhalant exposure in rheumatoid arthritis

Area of Science:

• Immunology
• Environmental Health
• Rheumatology

Background:

• The mucosal origins hypothesis suggests lung mucosal immune responses to environmental exposures initiate rheumatoid arthritis (RA).
• Cigarette smoke (CS) and crystalline silica (c-silica) are linked to RA risk, particularly in genetically susceptible individuals (HLA-DRB1 alleles).
• These exposures correlate with autoantibodies like anti-citrullinated peptide antibodies (ACPA) and rheumatoid factor (RF).

Purpose of the Study:

• To review evidence connecting inhalant exposures to RA pathogenesis.
• To evaluate existing animal models for studying RA initiation and progression related to environmental factors.
• To identify needs for improved models that incorporate genetic susceptibility and gene-environment interactions.

Main Methods:

• Literature review synthesizing epidemiological and experimental data.
• Analysis of animal models, including collagen-induced arthritis (CIA), for their relevance to RA initiation.
• Evaluation of the lung-joint axis and gene-environment interactions in RA pathogenesis.

Main Results:

• Epidemiological data supports a strong association between CS, c-silica exposure, and RA risk.
• Current animal models often fail to replicate the early lung mucosal events and gene-environment interactions crucial for RA onset.
• Variability in experimental outcomes highlights the need for standardized exposure protocols.

Conclusions:

• Environmental inhalant exposures are implicated in the early stages of RA pathogenesis via lung mucosal immune responses.
• Improved animal models incorporating genetic susceptibility and standardized exposures are essential for understanding RA mechanisms.
• Further research is critical for developing preventive strategies against inhalant exposure-induced RA.