Chitoheptaose

Apoptosis, also called programmed cell death, is generally characterized by distinct morphological characteristics.

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.

Selecting a suitable non-mouse animal model is a structured decision based on the research question, required anatomy or physiology, disease mechanism, endpoint feasibility, translational relevance, and ethical justification. Non-mouse models are preferred when mice cannot reproduce key human-relevant features, such as organ size, surgical anatomy, cardiovascular physiology, neuroanatomy, immune features, pharmacology, toxicology, or long-term clinical procedures. Candidate species may include rats, rabbits, guinea pigs, ferrets, zebrafish, pigs, sheep, goats, dogs, cats, horses, and non-human primates, but each species must be justified by its specific scientific advantage rather than convenience or tradition. Unresolved questions include how to quantify translational superiority across species, how to balance increased biological relevance against higher ethical burden, and when human-derived systems or new approach methodologies should replace animal use.

Apoptosis is a regulated, generally non-lytic cell-death pathway that removes unwanted, damaged, infected, or abnormal cells through coordinated morphological changes, caspase activation, DNA fragmentation, and membrane remodeling. The intrinsic apoptosis pathway is controlled mainly by mitochondrial outer membrane permeabilization, BCL-2 family proteins, cytochrome c release, apoptosome formation, caspase-9 activation, and downstream executioner caspase-3/7 activation. The extrinsic apoptosis pathway is initiated by death receptors such as Fas, TNFR, and TRAIL receptors, which recruit adaptor proteins and activate caspase-8 before engaging executioner caspases or mitochondrial amplification through BID cleavage. Apoptosis is linked to many phenotypes, including cancer cell killing, tissue homeostasis, immune regulation, neurodegeneration, infection response, and treatment-induced cytotoxicity; unresolved questions include how apoptosis interacts with necroptosis, pyroptosis, ferroptos

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

Pyroptosis is a lytic inflammatory cell-death pathway executed by gasdermin pores, most classically through inflammasome-mediated activation of caspase-1, cleavage of gasdermin D, membrane pore formation, LDH release, and secretion of IL-1β and IL-18. The canonical pathway is commonly modeled by priming cells with an inflammatory signal such as LPS to induce pro-IL-1β and inflammasome components, followed by an activation signal such as ATP or nigericin to activate NLRP3, ASC speck formation, caspase-1 cleavage, GSDMD cleavage, cytokine release, and pyroptotic membrane rupture. The non-canonical pathway is triggered when cytosolic LPS activates mouse caspase-11 or human caspase-4/5, leading to GSDMD cleavage and pyroptosis, and this can secondarily activate NLRP3-dependent IL-1β release. Pyroptosis is linked to inflammatory injury, infection, cancer, liver disease, ocular disease, placental inflammation, and other disease phenotypes, but unresolved questions include which gasdermin fam

Choosing the right model animal is a validity-driven decision in which the species, strain, sex, age, genetic background, disease-induction method, outcome measures, and welfare burden must match the scientific question rather than laboratory tradition or convenience. A model should be selected by judging face validity, construct validity, and predictive validity: whether it resembles the human phenotype, whether it reproduces relevant mechanisms, and whether results are likely to predict human biology or treatment response. Animal studies often fail to translate because of species differences, weak disease resemblance, poor experimental design, inadequate reporting, publication bias, and underuse of randomization, blinding, and sample-size justification. Unresolved questions include how to rank competing models objectively, how much human-disease complexity must be reproduced for a given objective, and when non-animal systems such as organoids, ex vivo tissue, or computational models