Monophosphoryl lipid A induces protection against LPS in medullary thick ascending limb through a TLR4-TRIF-PI3K signaling pathway
| Autor: | David W. Good, Thampi George, Bruns A. Watts, Edward R. Sherwood |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Lipopolysaccharides
Male 0301 basic medicine Medullary cavity Physiology Monophosphoryl Lipid A In Vitro Techniques Pharmacology PI3K signaling Rats Sprague-Dawley Sepsis 03 medical and health sciences Animals Medicine Phosphorylation Extracellular Signal-Regulated MAP Kinases Protein Kinase Inhibitors Phosphoinositide-3 Kinase Inhibitors Mice Knockout Host resistance Kidney business.industry medicine.disease Renal Reabsorption Mice Inbred C57BL Perfusion Toll-Like Receptor 4 Adaptor Proteins Vesicular Transport Bicarbonates Lipid A 030104 developmental biology medicine.anatomical_structure Cytoprotection TRIF Immunology Loop of Henle TLR4 lipids (amino acids peptides and proteins) Phosphatidylinositol 3-Kinase business Proto-Oncogene Proteins c-akt Signal Transduction Research Article |
| Zdroj: | American Journal of Physiology-Renal Physiology. 313:F103-F115 |
| ISSN: | 1522-1466 1931-857X |
| Popis: | Monophosphoryl lipid A (MPLA) is a detoxified derivative of LPS that induces tolerance to LPS and augments host resistance to bacterial infections. Previously, we demonstrated that LPS inhibits [Formula: see text] absorption in the medullary thick ascending limb (MTAL) through a basolateral Toll-like receptor 4 (TLR4)-myeloid differentiation factor 88 (MyD88)-ERK pathway. Here we examined whether pretreatment with MPLA would attenuate LPS inhibition. MTALs from rats were perfused in vitro with MPLA (1 µg/ml) in bath and lumen or bath alone for 2 h, and then LPS was added to (and MPLA removed from) the bath solution. Pretreatment with MPLA eliminated LPS-induced inhibition of [Formula: see text] absorption. In MTALs pretreated with MPLA plus a phosphatidylinositol 3-kinase (PI3K) or Akt inhibitor, LPS decreased [Formula: see text] absorption. MPLA increased Akt phosphorylation in dissected MTALs. The Akt activation was eliminated by a PI3K inhibitor and in MTALs from TLR4−/−or Toll/IL-1 receptor domain-containing adaptor-inducing IFN-β (TRIF)−/−mice. The effect of MPLA to prevent LPS inhibition of [Formula: see text] absorption also was TRIF dependent. Pretreatment with MPLA prevented LPS-induced ERK activation; this effect was dependent on PI3K. MPLA alone had no effect on [Formula: see text] absorption, and MPLA pretreatment did not prevent ERK-mediated inhibition of [Formula: see text] absorption by aldosterone, consistent with MPLA's low toxicity profile. These results demonstrate that pretreatment with MPLA prevents the effect of LPS to inhibit [Formula: see text] absorption in the MTAL. This protective effect is mediated directly through MPLA stimulation of a TLR4-TRIF-PI3K-Akt pathway that prevents LPS-induced ERK activation. These studies identify detoxified TLR4-based immunomodulators as novel potential therapeutic agents to prevent or treat renal tubule dysfunction in response to bacterial infections. |
| Databáze: | OpenAIRE |
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