The investigation of the ultrastructural neutrophil changes in alloxan‐induced diabetes in rats: response to a chemotactic challenge

Abstract

Experimental diabetes is one of the most popular conditions in which to study the relation between neutrophil leukocyte activity and periodontal destruction. The aetiology of neutrophil dysfunction in the gingival tissue associated with diabetes has yet to be clarified. Diabetes in rats decreases neutrophil chemotactic activity in proportion to the severity of this systemic disorder. The present study was carried out to evaluate the relationship between the severity of diabetes and the neutrophil response to two chemotactic agents, and to correlate the observed neutrophil defects with the degree of diabetes. In this study two chemotactic agents, casein (0.2 microl, 2 mg ml(-1)) or N-formylmethionylleucylphenylalanine (FMLP; 0.2 microl, 10(-4) M), were placed into the gingival crevices of alloxan-induced diabetic rats. Gingival biopsies were taken 15 min later and then at 5-min intervals up to 45 min and investigated by electron microscopy. Adherence and migration were observed in the rats with moderate diabetes 30 min after the application of casein. There was chemotaxis after 35 min of administration of the peptide FMLP. By 40 min neutrophils with pyknotic nuclei were observed. At 45 min neutrophils with a decreased number of granules were present. As the severity of the diabetes increased, the neutrophils degenerated and were structurally distorted. In the rats which had alloxan-induced diabetes there was abnormal periodontal damage. This damage is thought to be related to dysfunctional neutrophils. These findings many contribute to an answer to the following question: why is there an apparent variability in the susceptibility of periodontal breakdown in diabetics?

Relationship Between Periodontitis and Diabetes: Lessons From Rodent Studies

“…The hyperglycemic environment in diabetes leads to a variety of cellular alterations 13 . Impaired neutrophil function has been detected in diabetic patients and in rodent models 62,69,72,95‐98 . Proliferation and differentiation of periodontal osteoblasts are downregulated in diabetic rats, which was confirmed in in vitro experiments with human osteoblasts 77,99,100 .…”

“…Chemically induced type 1 diabetes (with alloxan or STZ) has been the most frequently used model, probably because of its low cost and the ease and rapidity of achieving diabetic animals. A large number of investigations 49,51‐81 indicated that alloxan‐ and STZ‐treated rodents had more severe spontaneous and induced periodontitis than non‐diabetic controls. In addition to the drug‐induced type 1 diabetes models, the genetically type 1 diabetic NOD mouse has been used in a periodontitis study 82 .…”

“…Thus, based on findings from human and rodent studies, the ultimate consequences of hyperglycemia in the periodontium are impaired host defense upon pathogens, prolonged inflammatory response, microvascular alterations, impaired new bone formation and repair, and impaired wound healing 19,60,62,69,112,129 (Fig. 1).…”

Neutrophil Function Impairment Is a Host Susceptibility Factor to Bacterial Infection in Diabetes

“…In situ evaluation of chemotaxis toward fMLP using T1DM rat neutrophils also revealed a deficiency in migration. This impairment in neutrophil chemotaxis was positively related to DM severity which was characterized by glycaemia values greater than 400 mg/dL [47]. In addition, blood neutrophils of diabetic animals presented a decreased migratory response to CXCL2/MIP-2 in vitro and in vivo compared to nondiabetic animals.…”