ABSTRACT
Objective To analyze the differences in immune system between Npc1 gene mutant (Npc1-/ -) and wild-type (Npc1+/ +) mice for better understanding the pathogenesis of Niemann-Pick disease type C1 (NPC1) from an immunological perspective and providing reference for NPC1 treatment in clinic.Methods Body, thymus and spleen weight of Npc1-/ -and Npc1+/ + mice aged (14±2) days, (42±2) days and (63±2) days (Day14±2 , Day42±2 and Day63±2 ) were recorded and the associated organ index were calcu-lated. White blood cell count in peripheral blood of mice aged Day42±2 was examined by routine blood test. Expression of cytokines at mRNA level in mouse peripheral blood was detected by qPCR. Percentages of CD4+, CD8+ and CD19+ lymphocytes in peripheral blood and spleen of mice aged Day42±2 were measured by flow cytometry. Apoptosis and senescence of spleen in mice aged Day63±2 were examined by immunofluores-cence and β-galactosidase staining. Results Compared with Npc1+/ + mice, there was no significant differ-ence in the weight of spleen and thymus in Npc1-/ - mice aged Day14±2; the weight of spleen in Npc1-/ - mice aged Day42±2 significantly increased, but the weight of thymus showed a significant decrease; furthermore, both the weight of spleen and thymus in Npc1-/ - mice aged Day63±2 significantly decreased; and the body weight of Npc1-/ - mice of each age group significantly decreased. Moreover, compared with Npc1+/ + mice, the absolute number of lymphocytes in the peripheral blood of Npc1-/ - mice aged Day42±2 showed no signifi-cant difference, but the percentage in whole white blood cells significantly decreased due to the significantly increased neutrophils. Expression of cytokines ( IL-1, IL-2, IFN-γ, TNF-α, IL-4, granzyme A and granzyme B) at mRNA level in the peripheral blood leukocytes of Npc1-/ - mice aged Day42±2 was abnormal as compared with that in Npc1+/ + mice. The number of T (CD4+ and CD8+) lymphocytes in Npc1-/ - mice aged Day42±2 significantly decreased, while the number of B (CD19+) lymphocytes increased significantly as com-pared with those in the Npc1+/ + mice. Compared with Npc1+/ + mice, apoptosis and senescence of the spleen in Npc1-/ - mice aged Day63±2 aggravated significantly. Conclusion The abnormal lipid metabolism triggered by Npc1 gene mutation causes severe immune dysfunction in Npc1-/ - mice. Therefore, immune dysfunction should be taken into full consideration when treating patients with NPC1, which might help improve the life quality and prolong the survival time.