Lipopolysaccharides (LPS), derived from Escherichia coli O55:B5, are essential components of the outer membrane of Gram-negative bacteria. Composed of lipid A, a core oligosaccharide, and an O-specific polysaccharide, LPS exhibits strong immunogenicity. It activates immune cells via the TLR4 receptor, induces chemotactic cell migration and cytokine secretion, and helps maintain the integrity of the bacterial outer membrane, protecting against bile salts and lipid-based antibiotics. LPS is commonly used to establish inflammatory models, including arthritis, chronic obstructive pulmonary disease (COPD), acute respiratory distress syndrome (ARDS), and gastrointestinal disease models.

Polyinosinic-polycytidylic acid (Poly(I:C)) is a synthetic double-stranded RNA (dsRNA) analog and an agonist of TLR3 as well as retinoic acid-inducible gene I (RIG-I) and melanoma differentiation-associated protein 5 (MDA5). It can induce innate immune responses in mammals and serve as a vaccine adjuvant to enhance both innate and adaptive immunity, while modulating the tumor microenvironment and directly inducing apoptosis in cancer cells. Poly(I:C) is commonly used to establish acute respiratory distress syndrome (ARDS) animal models for studying immune responses and disease mechanisms.

Lipopolysaccharides from Escherichia coli O111:B4 are key components of the outer membrane of Gram-negative bacteria. As a smooth-type LPS, they consist of lipid A, an R3-type core oligosaccharide, and an O-specific polysaccharide. These LPS molecules exhibit high immunogenicity, can trigger strong immune responses and gastric disorders by activating the TLR-4 receptor on immune cells, and help maintain the structural integrity of the bacterial outer membrane while protecting against bile salts and lipid-based antibiotics. They are widely used to establish inflammation-related disease models, such as chronic obstructive pulmonary disease (COPD) and acute respiratory distress syndrome (ARDS).