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Am J Respir Crit Care Med. 2012 Aug 1;186(3):246-54. doi: 10.1164/rccm.201201-0134OC. Epub 2012 May 31.

Interleukin 5 is protective during sepsis in an eosinophil-independent manner.

Author information

1
Department of Pulmonary and Critical Care Medicine, Oregon Health and Science University, Portland, Oregon 97216, USA.

Abstract

RATIONALE:

The immune response in sepsis is characterized by overt immune dysfunction. Studies indicate immunostimulation represents a viable therapy for patients. One study suggests a potentially protective role for interleukin 5 (IL-5) in sepsis; however, the loss of eosinophils in this disease presents a paradox.

OBJECTIVES:

To assess the protective and eosinophil-independent effects of IL-5 in sepsis.

METHODS:

We assessed the effects of IL-5 administration on survival, bacterial burden, and cytokine production after polymicrobial sepsis. In addition, we examined the effects on macrophage phagocytosis and survival using fluorescence microscopy and flow cytometry.

MEASUREMENTS AND MAIN RESULTS:

Loss of IL-5 increased mortality and tissue damage in the lung, IL-6 and IL-10 production, and bacterial burden during sepsis. Therapeutic administration of IL-5 improved mortality in sepsis. Interestingly, IL-5 administration resulted in neutrophil recruitment in vivo. IL-5 overexpression in the absence of eosinophils resulted in decreased mortality from sepsis and increased circulating neutrophils and monocytes, suggesting their importance in the protective effects of IL-5. Furthermore, novel data demonstrate IL-5 receptor expression on neutrophils and monocytes in sepsis. IL-5 augmented cytokine secretion, activation, phagocytosis, and survival of macrophages. Importantly, macrophage depletion before the onset of sepsis eliminated IL-5-mediated protection. The protective effects of IL-5 were confirmed in humans, where IL-5 levels were elevated in patients with sepsis. Moreover, neutrophils and monocytes from patients expressed the IL-5 receptor.

CONCLUSIONS:

Taken together, these data support a novel role for IL-5 on noneosinophilic myeloid populations, and suggest treatment with IL-5 may be a viable therapy for sepsis.

PMID:
22652030
PMCID:
PMC3423456
DOI:
10.1164/rccm.201201-0134OC
[Indexed for MEDLINE]
Free PMC Article

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