Diagnostic assays for myeloperoxidase and myeloperoxidase deficiency

Severe chronic non-bacterial osteomyelitis in combination with total MPO deficiency and responsiveness to TNFα inhibition

We describe a female patient suffering from severe chronic non-bacterial osteomyelitis (CNO) with systemic inflammation and advanced malnutrition and complete deficiency of myeloperoxidase (MPO). CNO is a rare autoinflammatory bone disorder associated with dysregulation of the innate immune system. MPO deficiency is a genetic disorder with partial or complete absence of the phagocyte peroxidase MPO. MPO deficiency has no established clinical phenotype but reports indicate increased susceptibility to infection and chronic inflammation. The patient's symptoms began at 10 years of age with pain in the thighs, systemic inflammation and malnutrition. She was diagnosed with CNO at 14 years of age. Treatment with nonsteroidal anti-inflammatory drugs, corticosteroids, bisphosphonates or IL1-receptor antagonists (anakinra) did not relieve the symptoms. However, the patient responded instantly and recovered from her clinical symptoms when treated with TNFα blockade (adalimumab). Three years after treatment initiation adalimumab was withdrawn, resulting in rapid symptom recurrence. When reintroducing adalimumab, the patient promptly responded and went into remission. In addition to clinical and laboratory profiles, neutrophil functions (reactive oxygen species, ROS; neutrophil extracellular traps, NETs; degranulation; apoptosis; elastase activity) were investigated both in a highly inflammatory state (without treatment) and in remission (on treatment). At diagnosis, neither IL1β, IL6, nor TNFα was significantly elevated in serum, but since TNFα blockade terminated the inflammatory symptoms, the disease was likely TNFα-driven. All neutrophil parameters were normal both during treatment and treatment withdrawal, except for MPO-dependent intracellular ROS- and NET formation. The role of total MPO deficiency for disease etiology and severity is discussed.

The Mucosal Innate Immune Response in Primary Human Papillomavirus Infection: A Pilot Study

OBJECTIVES

The purpose of the study was to evaluate the mucosal immune response in women affected by primary human papillomavirus (HPV) infection, in comparison with HPV-negative women with no previous history of HPV.

METHODS

A case-control study comparing the activity of myeloperoxidase (MPO) and lactoferrin (LF) between 19 HPV-positive and 19 HPV-negative women matched for age. Plasmatic and cervicovaginal levels of polymorphonuclear neutrophils (PMN) exhibiting MPO and LF receptors were measured using cytofluorimetric analysis and expressed as mean of percentages.

RESULTS

Cervicovaginal levels of MPO-/LF- PMN were lower among HPV-negative women, with a mean rate of 18.81% (SD, 21.38), as opposed to a mean rate of 35.56% (SD, 21.02) (P = 0.020) in HPV-positive women. A similar significant difference was not proven in plasma. The mean rates of plasmatic levels of MPO-/LF- PMN were 36.21% (SD, 16.87) and 36.93% (SD, 10.54) (P = 0.875) in cases and controls, respectively. All patients were evaluated 1 year later, and only 6 cases became negative.

CONCLUSIONS

The presence of MPO-/LF- PMN has been considered as a marker of lower rate of apoptosis of HPV-infected cells. This could explain why HPV-positive women are less capable to deal with a primary infection.

Relationship between glycemic control and histochemical myeloperoxidase activity in neutrophils in patients with type 2 diabetes

BACKGROUND

Myeloperoxidase (MPO) is a lysosomal hemoprotein found in the azurophilic granules in neutrophils. Myeloperoxidase plays an important role in oxygen-dependent killing of bacteria, fungi, virus and malignant cells. Diabetes mellitus (DM) is listed among conditions that may lead to secondary MPO deficiency in neutrophils but inconsistent results concerning MPO activity in diabetic patients have been reported in the literature. In this study, we aimed to evaluate the relationship between glycemic control in patients with type 2 DM and MPO activity in neutrophils from a histochemical perspective.

METHODS

The study included 40 patients with type 2 DM with poor glycemic control, 30 patients with type 2 DM with good glycemic control and 31 healthy controls. Peripheral blood smears were analyzed for each patient included in the study. Myeloperoxidase dye was used for staining. Myeloperoxidase ratios in neutrophil were evaluated for proportions of staining with MPO in 100 neutrophils in each smear. SPSS 16.0 version was used for statistical analyses.

RESULTS

Myeloperoxidase ratios in neutrophils were 70 (58.5-80) in type 2 DM patients with poor glycemic control compared to 80 (73.75-90) in those with good glycemic control and 88 (78-92) in healthy controls. The DM group with poor glycemic control was statistically significantly different from the other groups (p < 0.001).

CONCLUSIONS

Poor glycemic control in diabetic patients results in decreased MPO activity in neutrophils histochemically.