Lipopolysaccharides, from Proteus mirabilis  (Synonyms: LPS, from bacterial (Proteus mirabilis))

Lipopolysaccharides, from Proteus mirabilis are lipopolysaccharide endotoxins and TLR-4 activators derived from Proteus mirabilis, classified as S-type LPS, which can activate pathogen-associated molecular patterns (PAMP) of the immune system and induce cellular secretion of migrasomes. Lipopolysaccharides, from Proteus mirabilis exhibit a typical three-part structure: O-antigen, core oligosaccharide, and lipid A. Proteus mirabilis is a major pathogen causing urinary tract infections and may also contribute to rheumatoid arthritis. Lipopolysaccharides, from Proteus mirabilis also exhibit potential anti-tumor effects, demonstrating in vivo inhibitory activity against solid tumors such as meningosarcoma and Walker carcinosarcoma^[1][2].
It is recommended to prepare a solution with concentration ≥2 mg/mL. Vortex thoroughly for more than 10 minutes. Due to the adsorption characteristics of LPS, silanized container or low adsorption centrifuge tubes should be used for aliquoting and storage, and mix thoroughly before use.

TLR-4^[2]

Note:
Concentration and Time: Please do not rely solely on a single article to determine experimental conditions. It is recommended to review relevant literature based on the cell line and type of LPS before formal experiments, as the required induction time or optimal concentration for different inflammatory factors to reach their peak may vary. It is advisable to set concentration and time gradients to identify the optimal experimental scheme.
Detection Indicators: LPS does not necessarily induce cell death; therefore, it is not appropriate to determine the LPS modeling concentration and time solely by assessing cell viability. It is recommended to measure the expression or secretion of inflammatory factors.
Solvent Selection: Literature indicates that certain concentrations of DMSO can significantly inhibit LPS-induced inflammatory responses. In cellular experiments, it is recommended to prepare stock solutions using sterile water, followed by dilution with culture medium.
Container Selection: Due to the adsorption characteristics of LPS, it can bind to plastics and certain types of glass (especially at concentrations <0.1 mg/mL). The adsorption effect is relatively small when LPS concentrations exceed 1 mg/mL. Additionally, LPS tends to form micelles in solution. Therefore, when dissolving the powder, it is recommended to prepare concentrations of ≥2 mg/mL, and to vortex thoroughly for more than 10 minutes. If necessary, ultrasonic assistance may be used. For storage, please use silanized containers or low-adhesion centrifuge tubes. If glass containers are used, ensure to mix thoroughly for at least 30 minutes prior to use to re-dissolve any LPS adsorbed to the wall of the container.
Concentration Units: LPS does not have a uniform molecular weight because its molecules exhibit heterogeneity and aggregation. The molecular weight of naturally sourced LPS typically ranges from 10-100 kDa or even higher. Common dosing concentrations for LPS found in the literature are in terms of mass concentration, such as ng/mL and μg/mL, so it is sufficient to prepare solutions directly in mass concentration during experiments.
Filtration Sterilization: After dissolving LPS powder in water, saline, or PBS, the solution may appear turbid or colloidal, and in some cases, a microsphere distribution with diameters around 20-30 nm may be observed. When sterilizing by filtration, do not filter the stock solution directly. It is recommended to dilute to working solution first and then filter sterilize through a 0.22 μm filter membrane.
Differences Among Different Strain LPS: LPS of different catalog numbers comes from various bacterial strains, corresponding to different structural features such as lipid A, core polysaccharides, and O-antigens, which in turn affect the intensity of inflammation induction and TLR4-mediated signaling bias. Commonly referenced LPS catalog numbers for in vitro or in vivo inflammation model construction include HY-D1056 and HY-D1056A1. Moreover, in specific research contexts, specialized sources of LPS related to the studied bacterial strains may also be used. For example, HY-D1056D (from Porphyromonas gingivalis) is used in periodontal studies, while HY-D1056B3 (from Klebsiella pneumoniae) is relevant in pneumonia-related research. When selecting LPS, considerations should include the purpose of the experiment, sensitivity of the cell line, and other factors.

Serum-mediated immunity functions by activating the complement cascade, producing the membrane attack complex C5b-9, which exerts its own bactericidal activity. Lipopolysaccharides, from Proteus mirabilis are capable of activating the complement system and inducing C5b deposition. After incubation with serum for 3 hours (37 °C), Lipopolysaccharides, from Proteus mirabilis inhibit bacterial viability^[1].

MedChemExpress (MCE) has not independently confirmed the accuracy of these methods. They are for reference only.

Lipopolysaccharides, from Proteus mirabilis (minimum effective dose 0.005 mg/kg; intravenous or intraperitoneal injection; single dose) effectively suppress solid Ehrlich carcinoma (ED=0.005 mg/kg), Sarcoma 180, Sarcoma 37, and other solid tumors in mouse and rat tumor-bearing models, causing complete regression of some tumors. However, Lipopolysaccharides, from Proteus mirabilis are ineffective against ascites-type tumors. Lipopolysaccharides, from Proteus mirabilis can block blood flow in tumor tissues, causing the injected material to be "locked out" or "locked in." Lipopolysaccharides, from Proteus mirabilis can also be combined with anti-tumor drugs such as 6-mercaptopurine (HY-13677) and Cyclophosphamide (HY-17420) to enhance the inhibitory effects on refractory tumors like Meningeal sarcoma MS-147 and Walker carcinosarcoma 256^[2].

MedChemExpress (MCE) has not independently confirmed the accuracy of these methods. They are for reference only.

Solid

White to off-white

[Lipopolysaccharides, from Proteus mirabilis]

Room temperature in continental US; may vary elsewhere.

• [1]. Arabski M, et al. The presence of anti-LPS antibodies and human serum activity against Proteus mirabilis S/R forms in correlation with TLR4 (Thr399Ile) gene polymorphism in rheumatoid arthritis. Clin Biochem. 2012 Nov;45(16-17):1374-82.  [Content Brief]

  [2]. Nakahara M, et al. Effect of Lipopolysaccharide from Proteus mirabilis, alone or with Antitumor Agents, against Experimental Animal Tumors[J]. Agricultural and Biological Chemistry, 1976, 40(6): 1201-1208.