Fibulin‐2: A potential regulator of immune dysfunction after bone trauma

OBJECTIVES: To reveal the relationship between the fibulin‐2 protein and immune dysfunction after bone trauma. METHODS: Individuals who were admitted to the study were divided into a bone trauma group, a recovered from bone trauma group and a volunteer without bone trauma group based on the reason for admission. Fibulin‐2 levels in the three groups were compared. Fibulin‐2‐knockout (fibulin‐2 (−/−)) mice and wild‐type (WT) mice were used to detect susceptibility to infection. Hematoxylin and eosin (HE) staining and immunohistochemical staining were employed to observe pathological changes in each organ from fibulin‐2 (−/−) mice and WT mice. RESULTS: In total, 132 patients were enrolled in this study. The fibulin‐2 level in the bone trauma group was lower than that in the recovered bone trauma group (3.39 ± 1.41 vs. 4.30 ± 1.38 ng/mL, t = 2.948, p < .05) and also lower than that in the volunteers without bone trauma group (3.39 ± 1.41 vs. 4.73 ± 1.67 ng/mL, t = 4.135, p < .05). Fibulin‐2 (−/−) mice are more prone to infection. Compared with those in WT mice, spleen function and thymus function in fibulin‐2 (−/−) mice were impaired. Immunohistochemical staining revealed that compared with those in WT mice, significantly fewer CD4+ T cells, CD8+ T cells, and CD19+ B cells were noted in the spleen and thymus of fibulin‐2 (−/−) mice. CONCLUSIONS: The plasma fibulin‐2 level was lower in patients with bone trauma. Decreased fibulin‐2 is associated with immune dysfunction after bone trauma.