Selective intestinal decontamination with norfloxacin enhances a regulatory T cell-mediated inflammatory control mechanism in cirrhosis

Liver Int. 2016 Dec;36(12):1811-1820. doi: 10.1111/liv.13172. Epub 2016 Jun 21.

Abstract

Background & aims: Norfloxacin exerts immunomodulatory effects in cirrhosis beyond its bactericidal activity. We aimed at identifying the role of regulatory T (Treg) cells in the norfloxacin mechanism that compensates the inflammatory environment in cirrhosis.

Patients & methods: Consecutively admitted patients with cirrhosis and ascitic fluid (AF) with: spontaneous bacterial peritonitis (SBP), non-infected AF, and norfloxacin as secondary SBP prophylaxis (SID group). Tregs were defined by flow-cytometry as CD4+ CD25+ FoxP3+ cells. Dendritic cells (DCs) were purified for co-stimulatory signalling evaluation and norfloxacin and IL-10 levels were measured in serum. Wildtype and recombination activating gene 1 (Rag1)-deficient mice with CCl4 -induced cirrhosis were used for adoptive-transfer experiments using naïve CD4+ T cells and Tregs.

Results: Eighty-four patients were included. Treg percentage was significantly increased in SID patients compared with SBP or non-infected AF patients. A positive correlation was observed between Tregs and serum norfloxacin and IL-10 levels. DCs from SID patients showed a significantly decreased expression of CD80 and CD86 compared with SBP and non-infected AF patients and correlated with norfloxacin levels. Modulation of co-stimulatory signalling by norfloxacin was not detected in Rag1-deficient mice and Rag1-deficient mice reconstituted with naïve T-cells. However, reconstitution with naïve T-cells and Tregs was associated with significantly downregulated CD80 and CD86 expression in the presence of norfloxacin. Norfloxacin immunomodulatory effect on IL-2 and IFN-gamma reduction and on the increase of IL-10 was significantly achieved only when the Tregs were restored in Rag1-deficient mice.

Conclusions: These results provide a plausible mechanism for the immunomodulatory effects of norfloxacin in cirrhosis beyond its bactericidal effect.

Keywords: bacterial translocation; cirrhosis; norfloxacin; regulatory T cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adoptive Transfer
  • Aged
  • Animals
  • Anti-Bacterial Agents / therapeutic use*
  • B7-1 Antigen / metabolism
  • B7-2 Antigen / metabolism
  • Bacterial Infections / drug therapy*
  • Bacterial Translocation / drug effects*
  • Dendritic Cells / drug effects
  • Female
  • Forkhead Transcription Factors / metabolism
  • Humans
  • Interleukin-10 / blood
  • Interleukin-2 / blood
  • Liver Cirrhosis / complications*
  • Liver Cirrhosis / microbiology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Middle Aged
  • Norfloxacin / therapeutic use*
  • Peritonitis / drug therapy*
  • Peritonitis / microbiology
  • T-Lymphocytes, Regulatory / drug effects
  • T-Lymphocytes, Regulatory / immunology*

Substances

  • Anti-Bacterial Agents
  • B7-1 Antigen
  • B7-2 Antigen
  • Forkhead Transcription Factors
  • IL10 protein, human
  • IL2 protein, human
  • Interleukin-2
  • Interleukin-10
  • Norfloxacin