New Studies of Pathogenesis of Rheumatoid Arthritis with Collagen-Induced and Collagen Antibody-Induced Arthritis Models: New Insight Involving Bacteria Flora

Table 1

Similarities and differences between CAIA and CIA animal models. CFA: Complete Freund’s adjuvant, RA: rheumatoid arthritis, CIA: Collagen-Induced Arthritis, and CAIA: Collagen Antibody-Induced Arthritis.

	CIA model	CAIA model
Induction method	Type II collagen/CFA	Monoclonal antibodies against type II collagen
Feature of arthritis	Polyarthritis	Polyarthritis
Similarities to human RA	(i) Activates adaptive immune system.; (ii) Produces antibodies against specific epitopes on type II collagen in joints.; (iii) Synovial inflammation due to infiltrating immune cells.; (iv) Cartilage and bone destruction.; (v) Increases RF and ACPA	(i) Antibodies against specific epitopes on type II collagen in joints.; (ii) Synovial inflammation due to infiltrating immune cells.; (iii) Cartilage and bone destruction.
Advantages	(i) Study CIA development in relation to the adaptive immune systems.; (ii) Study immunity specific to cartilage.; (iii) No sex-bias	(i) Induces arthritis in many mouse strains.; (ii) Develops consistent arthritis severity and with almost 100% incidence.; (iii) Effectively studies test articles in a short study period (1-2 weeks).; (iv) RF and ACPA negative.; (v) No sex-bias
Disadvantages	(i) Restricted to select mouse strains.; (ii) Animal housing conditions can affect arthritis severities and incidences.; (iii) A long study period due to the slow onset of arthritis (1-2 months).; (iv) Strongly affected by CFA presence.	(i) Does not involve the full spectrum of immune activation.; (ii) Animal housing conditions can affect arthritis severities and incidences.