HMGB1-TLR4 Interactions: Mediators of Kidney Lung Crosstalk? Dept of Emergency and Critical Care Medicine The University of Tokyo Kent Doi, MD. PhD
Organ crosstalk in AKI Grams ME, Rabb H. Kidney Int. 2012;81:942-8.
Lung injury induced by AKI Rat ischemia/reperfusion (IR), bilateral nephrectomy (BNx) Reduced ENaC, Na-K-ATPase, AQP5 expression in the lung ENaC :Nothern blot Na-K-ATPase :Western blot AQP-5 :Western blot Kramer AA and Rabb H. KI 55:2362,1999
Lung injury induced by AKI Mouse IR, BNx models Neutrophil infiltration in the lung Blood cytokine elevation (IL-6, 10, KC, GCSF) Serum IL-6 Hoke TS and Faubel S. JASN 18:155,2007 Klein CL and Faubel S. KI 74:901,2008
Neutrophil count (400x field) Lung NE activity/protein ratio (nmol/mg) Lung injury induced by AKI Pulmonary neutrophil infiltration in BNx was reduced by a neutrophil elastase inhibitor (Sivelestat). (A) Sham (B) 6 hr Pulmonary NE activity (A) 25.0 * ** 20.0 15.0 Sham BNx+saline BNx+ONO (C) 24 hr (D) 20 15 10 * * *** Sham BNx+saline BNx+ONO * * *** 10.0 5.0 5 0 6h 24h 0 6h 24h Ishii T/Doi K. Am J Pathol 2010
Lung injury induced by AKI What is the possible mediator/pathway? 1. Previous studies showed Neutrophil infiltration to the lung Role of IL-6 and neutrophil elastase 2. Not only IR but BNx induced lung injury uremic toxin?? Can we remove the molecule by RRT methods?? Hypothesis TLR4 HMGB1 pathway may contribute to lung injury induced by AKI.
Lung injury induced by AKI What is the possible mediator/pathway? Language in lung-kidney crosstalk? High-mobility group protein B1 (HMGB1) 1. DNA-binding protein in nucleus. 2. Secreted from Mono/MΦ as an inflammatory mediator 3. Be increased in renal dysfunction. Toll-like receptor 4 (TLR4) 1. Recognize pathogen-associated molecular patterns (PAMPs) such as LPS, HSPs, etc. 2. Activates innate immunity.
HMGB1 (high-mobility group protein B1) BNx, 5/6Nx increased blood HMGB1 concentration. Leelahavanichkul A/Star RA. Kidney Int 2011; 80, 1198 1211
Lung injury induced by AKI What is the language in lung-kidney crosstalk? 1. HMGB1 is a possible TLR4 agonist. 2. TLR4 induces inflammation including neutrophil activation. HMGB1 elevation in BNx TLR4 activation by HMGB1 Neutrophil infiltration to lung BNx, bilateral nephrectomy
A spontaneous LPS resistant mouse strain (C3H/HeJ) has a mutation in the TLR4 gene. A spontaneous mutation occurred in C3H/HeJ mice at the LPS response locus (later identified as a mutation in the TLR4 4 gene) making C3H/HeJ mice endotoxin resistant. Proline with Histidine at 712 of the polypeptide chain (exon 3). Poltorak A. Science. 1998;282:2085-8.
HMGB1/TLR4 in BNx-induced lung injury TLR4 mutant C3H/HeJ mice were more resistant to lung injury caused by BNx compared with TLR4-wildtype C3H/HeN mice Pulmonary neutrophil infiltration C3H/HeN (TLR4-wild) C3H/HeJ (TLR4-mutant) Doi K. Kidney Int 2014
HMGB1/TLR4 in BNx-induced lung injury TLR4 mutant C3H/HeJ mice were more resistant to lung injury caused by BNx compared with TLR4-wildtype C3H/HeN mice 5 4 3 2 1 TNF-α # * # 15 10 5 KC # * # 1.0 0.8 0.6 0.4 0.2 IL-6 # * # 0 C3H/HeN Sham C3H/HeJ Sham C3H/HeN C3H/HeJ BNx BNx 0 C3H/HeN Sham C3H/HeJ Sham C3H/HeN C3H/HeJ BNx BNx 0 C3H/HeN Sham C3H/HeJ Sham C3H/HeN C3H/HeJ BNx BNx Doi K. Kidney Int 2014
HMGB1/TLR4 in BNx-induced lung injury Oxidative stress and vascular leak were reduced in TLR4 mutant C3H/HeJ mice Oxidative stress (HHE accumulation) Vascular permeability (Evans blue dye) C3H/HeN (TLR4-wild) C3H/HeJ (TLR4-mutant) Doi K. Kidney Int 2014
HMGB1/TLR4 in BNx-induced lung injury Plasma HMGB1 was increased in wild/mutant mice. Treatment with anti-hmgb1 Ab reduced neutrophil infiltration only in TLR4 wild-type C3H/HeN mice. Plasma HMGB1 Neutrophils in lung Doi K. Kidney Int 2014
HMGB1/TLR4 in BNx-induced lung injury Anti-HMGB1 Ab reduced KC but not TNF-α and IL-6. TNF-α Plasma HMGB1 KC Neutrophils in lung Control IgY Anti-HMGB1 Control IgY Anti-HMGB1 IL-6 Murine IL-8 homologues KC is known as neutrophil chemotactic factor. Control IgY Anti-HMGB1 Doi K. Kidney Int 2014
Lung injury induced by AKI Possible role of HMGB1 TLR4 pathway in kidney-lung cross-talk HMGB1 elevation in BNx TLR4 activation by HMGB1 Neutrophil infiltration to lung via KC? BNx, bilateral nephrectomy
HMGB1 (high-mobility group protein B1) Removal of HMGB1 by blood purification (vitro) AN69ST showed a markedly high clearance rate of HMGB1. Removal of HMGB1 was mostly by absorption. Nishida O. Ther Aphe Dial 2011
Summary AKI is significantly associated with high mortality in context with multiple organ failure in the ICUs. Other organ injury could be induced/amplified by AKI. In lung-kidney crosstalk, TLR4 HMGB1 pathway plays a crucial role.