New insights into sepsis induced renal injury. Indiana University

Transcription

1 New insights into sepsis induced renal injury Pi C D h MD Pierre C. Dagher, MD Indiana University

2 Fact Sepsis and septic shock remain the most important cause of Acute Kidney Injury (AKI) in critically ill patients, and account for more than 50% of cases of AKI in the ICU Current Opinion in Critical Care 2003, 9:

3 What is Sepsis? Syndrome caused by the interaction of a pathogen with the host immune system Dynamic sets of events characterized by a maladaptive response of the immune system.

4 Clinical Definition of Sepsis SIRS (fever, tachycardia, leukocytosis ) +evidence of infection Sepsis Severe Sepsis +organ dysfunction, hypotension Septic shock +hemodynamic collapse, pressors MODS +complete failure of homeostasis

5 A Disorder Due to Uncontrolled Inflammation? 1972, Lewis Thomas : The micro organisms that seem to have it in for us..turn out.. to be rather more like bystanders.it is our response to their presence that makes the disease Thomas L. Germs. NEJM :553-5

6 ..or Profound Immunosuppression? 2006: Richard Hotchkiss The failure of more than 30 clinical trials to treat sepsis by controlling this cytokine response requires a 'rethink' of the molecular mechanism underpinning i the development of sepsis remarkable new studies indicate that most deaths from sepsis are actually the result of a substantially impaired immune response that is due to extensive death of immune effector cells. Hotchkiss and Nicholson, Nat Rev Immunology 2006

7 Riedemann, et al, Nature Medicine, 9 (5) May 2003

8 Russell JA, NEJM 2006 Sepsis and RCTs

9 Russell JA, NEJM 2006 Sepsis and RCTs

10 Problem in studying sepsis Non-homogeneity of the patient population enrolled in clinical studies The immune system in a septic individual undergoes substantial modifications during sepsis Animal model do no reflect the clinical picture it in humans

11 Complexity of sepsis literature 1. What animal sepsis model is being used 2. Studies in same or different species 3. Age of animals 4. Single bacteria vs Polymicrobial 5. Are the rates of bacterial release comparable 6. What bacterial strain/endotoxin is being used 7. Antibiotics 8. Are the doses of endotoxin comparable 9. What is the end point: organ damage vs mortality 10.Systemic vs Local TLRs

12 Weighardt et al. J. Immunol MyD88 detrimental role in sepsis CASP vs CLP Peck Palmer. J. Leuk. Biol MyD88 protective role in sepsis Mortality vs AKI Dear et al. Kidney Int MyD88 detrimental role in sepsis

13 Pfeiffer Describes endotoxin LPS = endotoxin C3H/Hej Lps TNF meditates LPS shock LBP CD Nomura TLR1 Medzhitov TLR4 Drosophila Toll Toll and yeast Beutler Lps = TLR4

14 C3H/HeJ Mouse and LPS C3H/HeJ mutant phenotype arose through spontaneous mutation between 1960 and 1968 C3H/HeJ strain exhibits natural tolerance to otherwise lethal doses of LPS Hyporesponsive phenotype under the control of a single locus, Lps existing in two allelic li forms, Lps n (responsive) and Lps d (hyporesponsive) Lps locus assigned to chromosome 4 J. Exp. Med. Volume 189, Number 4, February 15,

15 Akira and Takeda 2004 TLRs and their ligands

16 Organism Pathogens Toll-like like Receptors

17 Branching Nature of TLR Signaling El-Achkar and Dagher, Nature Clinical Practice Nephrology, 2006

18 DANGER PAMPS DAMPS TLRs Innate immunity Infectious diseases Inflammatory Immune disorders

19 Science 1998

20 Advantages Disadvantages E Simple and inexpensive Well standardized dose vasoconstriction ARF requires high doses high mortality, Short duration. variable response Systemic hemodynamics like No MODS. B human. Expensive and hard in large Bacterial dose standardized animals. Standard supporting measures, often lacking. I Simple and inexpensive. Rapid onset reproduces aspects of sepsis in humans control over the dose of bacteria. Too severe in large animals. ATN not produced clinically or pathologically. C Simple and inexpensive. Septic shock with MODS response variable human like ATN not reproduced. Heyman, et al Animal models of acute tubular necrosis, Curr Opin Crit Care 2002, 8:

21 Animal Models of Sepsis endotoxin Bacteria CASP CLP CLP + Age + Abx More Severe Cytokine storm Less severe

22 Cytokine Release in CLP Vs Endotoxin Infusion TNF peak CLP= 0.09 ± 0.04 U/ml TNF 1 hr LPS (50mg/kg)= 37.5 ± 146U/ 14.6 U/ml Clinical and Diagnostic Laboratory Immunology,1995, 2: 549

23 Causative Agents for Kidney Injury Hemodynamic factors Renal microvascular Systemic: important in later phase or with high load of pathogen Non-hemodynamic Renal cytokine effects Direct action of micro-organisms i?

24 TLRs Immune system Organ specific

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27 Localization of TLR4 Sham CLP El-Achkar et al AJP Renal 2005 in press

28 TLR4 in Proximal Tubules Sham CLP El-Achkar et al AJP Renal 2005

29 Localization of CD14 Sham CLP El-Achkar et al AJP Renal 2005 in press

30 Intra-vital 2 photon microscopy Fluorescent LPS injected as a tracer of endogenous LPS followed by imaging Dunn K et al. Am J Physiol Cell Physiol 2002

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43 TMRM

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46 WT Sl100 Sal E 5 Sal

47 WT CD14 KO Sal 100 E5 Sal

48 WT TRIF KO Sal 100 E5 Sal100 48

49 CD14 KO E5 Sal100 E5 Sal100 + poly I:C 49

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51 TLR4KO/WT chimera E5Sal100 TLR4 KO/WT TLR4 KO/WT Sal 100 E5 Sal

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53 M2 18% M2 41% 53

54 Tolerance LPS Toxicity Tolerance

55 Thanks to: Takashi Hato Rabih Kalakeche Zoya Plotkin Ken Dunn Ruben Sandoval NIH Funding

56 TLR2 in the kidney

57 TLR2 in the Kidney