RIPK2-IN-9

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.

Cytotoxicity assays are usually based on the assessment of cell membrane damage, which can also be indirectly detected by measuring cell viability. Detection methods include MTT assay, CKK-8 assay, LDH assay and ATP assay, etc.

The pull-down assay is an in vitro technique used to detect physical interactions between two or more proteins and an invaluable tool for confirming a predicted protein-protein interaction or identifying novel interacting partners. This method typically involves the use of affinity purification with various wash and elution steps.

Immunoprecipitation (IP) is an experimental method that uses the principle of antibody specific binding to purify and enrich target proteins.

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.

Bimolecular fluorescence complementation detects protein-protein proximity in living or fixed cells by fusing two candidate interaction partners to nonfluorescent N- and C-terminal fragments of a fluorescent protein; when the partners interact or remain close enough, the fluorescent fragments complement, mature, and generate a fluorescent signal at the site of the protein complex. The BiFC readout is fluorescence intensity and subcellular localization of the reconstituted fluorophore, which reflects formation or stabilization of a protein complex rather than direct biochemical binding kinetics; BiFC is therefore useful for mapping where interactions occur in cancer cells, neurons, macrophages, organoid-derived cells, or drug-screening systems, but results should be validated by independent assays such as co-IP or Western blot. BiFC signal formation is delayed by fluorophore maturation and can stabilize otherwise transient complexes, so it is not a real-time reversible interaction assay

The NLRP3 inflammasome is a cytosolic innate immune signaling platform that integrates priming signals and danger-signal activation to promote caspase-1 activation, maturation of IL-1β and IL-18, and gasdermin D-mediated pyroptotic cell death. The core experimental logic is to determine whether inflammatory disease phenotypes are driven by increased NLRP3 expression, ASC-containing inflammasome assembly, caspase-1 cleavage, GSDMD cleavage, and extracellular release of IL-1β/IL-18 rather than by nonspecific cell injury alone. The pathway is strongly linked to inflammation-related disease phenotypes because monosodium urate crystals activate NALP3/NLRP3 inflammasome signaling in gout-like crystal inflammation, cholesterol crystals activate NLRP3 inflammasomes in atherogenesis models, and DSS-induced intestinal inflammation has been reported to involve NLRP3 inflammasome activity. However, experimental colitis studies also show context-dependent protective effects of NLRP3 inflammasome co

Co-immunoprecipitation technology can verify protein interaction based on the specific immune reaction between antibodies and antigens.

The yeast two-hybrid assay detects binary protein-protein interactions by separating a transcription factor into a DNA-binding domain fused to a "bait" protein and a transcriptional activation domain fused to a "prey" protein; if bait and prey interact in yeast, the transcription factor is reconstituted and activates reporter genes such as HIS3, ADE2, lacZ, MEL1, or other selectable/readable reporters. The readout is yeast growth on selective medium and/or reporter activity, which reflects proximity-dependent transcriptional activation in the yeast nucleus rather than direct biochemical binding in the original mammalian, tumor, neuronal, macrophage, or organoid context. Because yeast two-hybrid can generate false positives and false negatives, interaction claims should be validated using independent assays such as co-immunoprecipitation, Western blot, immunofluorescence colocalization, BiFC, pull-down, or mammalian two-hybrid assays.