LPS-RS

TLR4 antagonist activity of LPS-RS

LPS from Rhodobacter sphaeroides

Lipopolysaccharide from the photosynthetic bacterium Rhodobacter sphaeroides (LPS-RS) is a potent antagonist of toxic hexa-acylated LPS in human and murine cells [1]. It also prevents LPS-induced shock in mice [1]. Complete competitive inhibition of LPS activity is possible at a 100-fold excess of the antagonist. LPS-RS does not induce TLR4 signaling but is detected by the LAL assay, the standard endotoxin detection assay.

 More details

Mode of action:

LPS-RS is penta-acylated, and like other under-acylated LPS, appears to use at least two distinct mechanisms to block LPS-dependent activation of Toll-like receptor 4 (TLR4). The primary mechanism consists of direct competition between under-acylated LPS and hexa-acylated LPS for the same binding site on MD-2, while the secondary mechanism involves the ability of under-acylated LPS-MD-2 complexes to inhibit the TLR4 agonist activity of hexa-acylated LPS-MD-2 complexes [2-5].

InvivoGen provides LPS-RS with two grades of purity:

• LPS-RS is a standard lipopolysaccharide (LPS) preparation extracted by a phenol-water mixture. It inhibits TLR4 activity, however, as LPS-RS contains other bacterial components, such as lipoproteins, it activates TLR2.
• LPS-RS Ultrapure is extracted by successive enzymatic hydrolysis steps and purified by the previously described phenol-TEA-DOC extraction protocol [6]. This process removes contaminating lipoproteins, and therefore LPS-RS Ultrapure does not activate TLR2 while retaining the ability to inhibit TLR4 activity. 

Learn more about TLR4 and its co-receptors

References:

1. Qureshi, N. et al., 1999. Nontoxic RsDPLA as a potent antagonist of toxic lipopolysaccharide. p. 687-98. In: Brade H., Opal  S. M.,  Vogel S. N., and Morrison D. C., eds. Endotoxin in Health and Disease. Marcel Dekker, New York.
2. Coats SR. et al., 2005. MD-2 mediates the ability of tetra-acylated and penta-acylated lipopolysaccharides to antagonize Escherichia coli lipopolysaccharide at the TLR4 signaling complex. J Immunol. 175(7):4490-8.
3. Teghanemt A. et al., 2005. Molecular basis of reduced potency of underacylated endotoxins. J Immunol. 175(7):4669-76.
4. Visintin A. et al., 2005. Pharmacological inhibition of endotoxin responses is achieved by targeting the TLR4 coreceptor, MD-2. J Immunol. 175(10):6465-72.
5. Saitoh S. et al., 2004. Lipid A antagonist, lipid IVa, is distinct from lipid A in interaction with Toll-like receptor 4 (TLR4)-MD-2 and ligand-induced TLR4 oligomerization. Int Immunol. 16(7):961-9.
6. Hirschfeld M. et al., 2000. Cutting edge: repurification of lipopolysaccharide eliminates signaling through both human and murine toll-like receptor 2. J Immunol. 165(2):618-22.

Figures

LPS-RS Standard (ST) is a potent activator of human (h)TLR2. HEK-Blue™ hTLR2 and HEK-Blue™ hTLR4 cells were incubated with increasing concentrations of LPS-RS ST. After overnight incubation in HEK-Blue™ detection medium, a SEAP detection growth medium, the response of hTLR2 and hTLR4 was assessed by determining the presence of SEAP in the supernatant. Data are expressed as optical density at 630 nm (±SEM).

LPS-RS ST is a potent antagonist of LPS-EK Ultrapure (UP). HEK-Blue™ hTLR4 cells were treated with 0.3 ng/ml LPS-EK UP and increasing concentrations of LPS-RS ST. After overnight incubation, the inhibition of LPS-induced hTLR4 activation was assessed by determining the presence of SEAP in the supernatant using QUANTI-Blue™ Solution. Data are expressed as optical density at 630 nm (±SEM).

LPS-RS Ultrapure (UP) does not activate both human (h)TLR2 and TLR4. The cells were incubated with increasing concentrations of LPS-RS UP. After overnight incubation in HEK-Blue™ detection medium, a SEAP detection growth medium, the response of hTLR2 and hTLR4 was assessed by determining the presence of SEAP in the supernatant. Data are expressed as optical density at 630 nm (±SEM).

LPS-RS UP is a potent antagonist of LPS-EK UP. HEK-Blue™ hTLR4 cells were treated with 0.3 ng/ml LPS-EK UP and increasing concentrations of LPS-RS UP. After overnight incubation, the inhibition of LPS-induced hTLR4 activation was assessed by determining the presence of SEAP in the supernatant using QUANTI-Blue™ Solution. Data are expressed as optical density at 630 nm (±SEM).

Specifications

LPS-RS

Specificity: TLR4 antagonist and TLR2 agonist

Solubility: 5 mg/ml in water

Working concentrations:

• TLR4 antagonist activity: 10 ng - 10 µg/ml
• TLR2 agonist activity: 10 ng/ml - 10 µg/ml

Quality Control

• Inhibition of TLR4 activation has been confirmed using HEK‑Blue™ TLR4 cells.
• The absence of TLR4 agonist activity has been confirmed using HEK‑Blue™ TLR4 cells.
• The presence of bacterial contamination (e.g. lipoproteins) in LPS-RS has been assessed using HEK-Blue™ TLR2 cells.

LPS-RS Ultrapure

Specificity: TLR4 antagonist

Solubility: 1 mg/ml in water

Working concentration:

• TLR4 antagonist activity: 10 ng - 10 µg/ml

Quality Control

• Inhibition of TLR4 activation has been confirmed using HEK‑Blue™ TLR4 cells.
• The absence of TLR4 agonist activity has been confirmed using HEK‑Blue™ TLR4 cells.
• The absence of bacterial contamination (e.g. lipoproteins) in LPS-RS Ultrapure has been confirmed using HEK-Blue™ TLR2 cells.

Contents

LPS-RS (Standard):

• 5 mg lipopolysaccharide from Rhodobacter sphaeroides (LPS-RS)
• 1.5 ml endotoxin-free water

LPS-PG Ultrapure:

• 1 mg lipopolysaccharide from Rhodobacter sphaeroides  Ultrapure (LPS-RS Ultrapure)
• 1.5 ml endotoxin-free water

LPS-RS is shipped at room temperature

Upon receipt, store at -20 °C.
 

Details

Toll-like receptor 4 (TLR4) primarily recognizes and is activated by a core component of the outer membrane of Gram-negative bacteria, lipopolysaccharide (LPS).  TLR4 requires interaction with a number of co-receptors including LPS-binding protein (LBP), CD14 and, myeloid differentiation protein 2 (MD-2) to bind to LPS and induce a signaling cascade. Ultimately, this leads to the activation of NF-κB and the production of pro-inflammatory cytokines.

LPS consists of a polysaccharide region that is anchored in the outer bacterial membrane by a specific carbohydrate-lipid moiety termed lipid A (also known as endotoxin). It is the lipid A region that is responsible for the immunostimulatory activity of LPS. 

Variation in lipid A, specifically the number of fatty acyl chains, among diverse bacterial species cause a vast difference in the biological activity of LPS. 

There are two major variations of lipid A:

• Hexa-acylated (6 fatty acid chains): a highly active agonist of TLR4 and is found commonly on pathogenic bacteria such as Escherichia coli and Salmonella spp.
• Under-acylated (4-5 fatty acid chains): induces a significantly lower host response and can be an antagonist of TLR4, by inhibiting, in a dose-dependent manner, the strong endotoxic response triggered by hexa-acylated LPS.

Structure of lipid A from Rhodobacter sphaeroides: