Collagen-induced arthritis (CIA) is an autoimmune murine model of rheumatoid arthritis in which immunization with type II collagen (CII) emulsified in an adjuvant induces a T cell- and autoantibody-driven inflammatory arthritis characterized by synovial hyperplasia, immune cell infiltration, and joint destruction. The model typically relies on genetically susceptible mouse strains (e. g. , DBA/1) and reproduces key features of human rheumatoid arthritis, including anti-collagen immune responses and progressive joint inflammation. Disease onset generally occurs within ~3-4 weeks after immunization, depending on antigen/adjuvant combinations and protocol variation. The immunopathology is driven by adaptive immune activation against CII, leading to systemic and local joint inflammation mediated by pro-inflammatory cytokines and effector immune cells, making CIA a standard preclinical platform for evaluating immunomodulatory and anti-arthritic interventions.
Inflammation Models
Inflammation modeling is the process of simulating and studying the inflammatory response in organisms through experimental means. This process involves the use of irritants, inflammatory substances, or pathogens to activate immune cells and inflammatory mediators. Inflammation modeling can be achieved through animal models such as mice and rats, as well as in vitro cell culture models. These models can be used to study the molecular mechanisms of inflammation, immune responses, and potential therapeutic targets. Inflammation modeling plays an important role in understanding disease development, drug development, and treatment strategies.
Related Experimental Schemes
Lipopolysaccharide (LPS)-induced endotoxemia is a widely used in vivo model of acute systemic inflammation in which LPS, a Gram-negative bacterial endotoxin, activates innate immune signaling primarily through TLR4, leading to rapid and transient induction of pro-inflammatory cytokines such as TNF-α, IL-6, and IL-1β in circulation and tissues. This cytokine surge is commonly used as a measurable readout of systemic inflammatory activation and immune dysregulation, and is typically assessed within hours after intraperitoneal LPS administration in mouse models of endotoxemia. The model captures key features of systemic inflammatory response syndrome, including cytokine release, immune cell activation, and downstream tissue responses, and has been used to evaluate anti-inflammatory interventions such as cytokine modulation, lipid mediators, and immune cell-targeting therapies.
Imiquimod (IMQ)-induced psoriasiform dermatitis is a widely used murine model in which topical application of IMQ, a Toll-like receptor 7 (TLR7) agonist, triggers innate immune activation in the skin and induces a psoriasis-like inflammatory cascade characterized by epidermal hyperplasia, immune cell infiltration, and cytokine production dominated by the IL-23/IL-17 axis. This inflammatory response is mediated through activation of dendritic cells and downstream induction of IL-23, IL-17A, IL-22, and related pro-inflammatory mediators, recapitulating key features of human plaque psoriasis and enabling mechanistic and therapeutic studies. The model is commonly induced using Aldara (5% IMQ cream) applied topically to murine skin, resulting in rapid onset of erythema, scaling, and thickening that can be quantified as disease severity indices and validated histologically.
Cotton pellet granuloma is a classical in vivo chronic inflammation model used to evaluate the anti-inflammatory potential of test substances by measuring their ability to inhibit granuloma tissue formation around an implanted foreign body (cotton pellet) in rodents. The method is based on the biological response to a sterile implanted material, which induces proliferative phase inflammation characterized by fibroblast proliferation and collagen-rich granuloma formation, and the final readout reflects the extent of chronic inflammatory tissue growth surrounding the pellet. In multiple preclinical pharmacological evaluations, inhibition of cotton pellet-induced granuloma formation has been used as an indicator of anti-inflammatory activity in both synthetic and natural product screening contexts.
Carrageenan-induced paw edema is an acute inflammation model in which intraplantar injection of carrageenan induces localized inflammatory swelling characterized by vascular permeability, leukocyte infiltration, and production of inflammatory mediators such as prostaglandins and cytokines, making it widely used to evaluate anti-inflammatory agents in vivo. The resulting paw volume or thickness increase is quantified over time as a direct readout of inflammatory intensity and drug efficacy, typically reflecting cyclooxygenase-mediated prostaglandin-driven edema formation and immune cell recruitment in peripheral tissue[20].
The TPA (12-O-tetradecanoylphorbol-13-acetate) and croton oil-induced mouse ear edema model is a well-established acute cutaneous inflammation system used to evaluate topical anti-inflammatory activity by measuring edema formation, neutrophil infiltration, vascular permeability, and cytokine-mediated skin responses in vivo. The inflammatory response is triggered by topical application of phorbol esters (TPA) or croton oil constituents, leading to rapid activation of protein kinase C signaling, leukocyte recruitment, and increased vascular permeability, which can be quantified by ear thickness, weight, dye extravasation, and biochemical markers such as myeloperoxidase (MPO) activity and pro-inflammatory mediators in ear tissue homogenates. This model is widely used for screening anti-inflammatory agents, where reductions in edema and inflammatory biomarkers reflect suppression of acute dermal inflammation and immune cell infiltration. Histological evaluation typically confirms epidermal
Contact hypersensitivity (CHS) dermatitis is a T cell-mediated delayed-type (Type IV) immune reaction in which low-molecular-weight haptens applied to the skin bind host proteins to form complete antigens, triggering sensitization followed by a secondary inflammatory response upon re-exposure (elicitation phase), which is commonly quantified by ear swelling as a readout of skin inflammation in murine models. This model is widely used to study allergic contact dermatitis because it is antigen-specific, reproducible, and reflects key immunological events including dendritic cell activation, T cell priming in draining lymph nodes, and effector T cell-driven tissue inflammation. DNFB- and oxazolone-induced CHS models are standard systems for evaluating both acute and chronic T cell-dependent skin inflammation and for testing immunomodulatory interventions.
The formalin-induced paw inflammation/nociceptive test is a chemical persistent pain model in rodents in which subcutaneous injection of formalin into the hind paw produces spontaneous nocifensive behaviors such as flinching and licking. The response is classically biphasic, consisting of an early acute phase (Phase I) reflecting direct activation of peripheral nociceptors (particularly C-fiber afferents), followed by a later prolonged phase (Phase II) associated with central sensitization in the spinal dorsal horn driven by sustained afferent input and inflammatory signaling. This model is widely used to evaluate analgesic and anti-inflammatory interventions because it captures both peripheral nociception and central sensitization processes within a single assay system.
Ovalbumin-induced allergic airway inflammation is a mouse model in which systemic sensitization to ovalbumin, usually with aluminum hydroxide adjuvant, is followed by airway ovalbumin challenge to induce allergic airway inflammation, eosinophil recruitment, mucus production, serum antigen-specific IgE, Th2 cytokine responses, and airway hyperresponsiveness to methacholine. The model is used to study allergen-driven airway inflammation and asthma-like immune responses, but it does not reproduce every feature of human asthma. The main readouts are bronchoalveolar lavage fluid cellularity, lung histopathology, airway hyperresponsiveness, serum OVA-specific IgE, and cytokines such as IL-4, IL-5, and IL-13 in bronchoalveolar lavage fluid or lung samples. Eosinophilia and Th2 cytokines reflect allergic type 2 inflammation, while methacholine responsiveness provides a functional airway-reactivity endpoint.
Zymosan-induced peritonitis is a sterile acute-inflammation model produced by intraperitoneal injection of zymosan, a yeast cell-wall particle preparation, followed by quantification of leukocyte recruitment and soluble inflammatory mediators in peritoneal lavage fluid. Low-dose zymosan peritonitis is commonly used as a self-resolving acute inflammation model in which neutrophil recruitment occurs early and monocyte/macrophage accumulation follows later. The assay readouts include total peritoneal leukocyte number, differential neutrophil and monocyte/macrophage counts, peritoneal cytokines and chemokines, plasma or peritoneal exudation, and optional lipidomic or metabolomic changes during inflammation and resolution. Early neutrophil recruitment after zymosan depends strongly on complement and mast-cell C5a receptor signaling, whereas later monocyte recruitment is linked to MCP-1/CCL2 production.
Dextran sulfate sodium (DSS)-induced colitis is generated by administering DSS in mouse drinking water, producing epithelial injury, barrier disruption, weight loss, diarrhea, fecal blood, colon shortening, histologic mucosal damage, and inflammatory mediator changes; the model is mainly used to study acute or chronic intestinal inflammation resembling selected features of ulcerative colitis. DSS injury is interpreted through clinical and tissue readouts rather than a single molecular endpoint: daily body weight, stool consistency, and bleeding are combined into a disease activity index, while colon length, histology, cytokines, myeloperoxidase activity, intestinal permeability, and tight-junction markers provide complementary measures of inflammation and barrier damage.
TNBS-induced colitis is produced by intrarectal delivery of 2,4,6-trinitrobenzene sulfonic acid in ethanol, where ethanol disrupts the mucosal barrier and TNBS haptenates colonic proteins, generating immune-mediated colonic inflammation with weight loss, diarrhea, ulceration, transmural injury, inflammatory-cell infiltration, and cytokine responses. The model is used as an experimental intestinal inflammation model with Crohn’s disease–like features, especially when Th1-type responses, IL-12–dependent inflammation, chronic relapsing inflammation, or fibrosis-related endpoints are studied.
