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Neutrophil dysfunction induced by hyperglycemia: modulation of myeloperoxidase activity

Cláudia de Souza Ferreira1, Tomaz Henrique Araújo, Marilene Lopes Ângelo

  • 1Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, UNIFAL-MG, Alfenas, Minas Gerais, Brazil.

Cell Biochemistry and Function
|May 22, 2012
PubMed

Insights

Hyperglycemia impairs neutrophil function in rats by decreasing myeloperoxidase (MPO) activity, which is crucial for killing Candida albicans. This leads to reduced phagocytic and microbicidal capabilities in diabetic neutrophils.

Area of Science:

  • Immunology
  • Biochemistry
  • Microbiology

Background:

  • Neutrophils are critical for host defense, employing enzymes like NADPH oxidase and myeloperoxidase (MPO) for microbial killing.
  • Hyperglycemia, a hallmark of diabetes, is known to affect immune cell function, potentially compromising innate immunity.

Purpose of the Study:

  • To investigate the impact of hyperglycemia on neutrophil enzyme activity, specifically NADPH oxidase and MPO.
  • To evaluate the consequences of altered enzyme function on the phagocytosis and microbicidal activity against Candida albicans in a rat model.

Main Methods:

  • Assessed NADPH oxidase activity using chemiluminescence and cytochrome C reduction.
  • Measured MPO activity via HOCl production and analyzed MPO expression using Western blot and immunofluorescence.
  • Evaluated Candida albicans phagocytosis and killing using microscopy and May-Grunwald-Giemsa staining.

Main Results:

  • Neutrophils from hyperglycemic rats showed slightly delayed ROS generation kinetics.
  • MPO expression was elevated, but MPO activity was significantly decreased in diabetic neutrophils.
  • Phagocytosis and killing of Candida albicans were impaired in neutrophils from hyperglycemic rats.

Conclusions:

  • Decreased MPO activity and subsequent reduced HOCl production contribute to impaired neutrophil phagocytic and microbicidal functions in hyperglycemic rats.
  • Myeloperoxidase plays a vital role in the microbicidal capacity of neutrophils, and its dysfunction under hyperglycemia has significant implications for host defense.

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