ABSTRACT
BACKGROUND: Lung transplant recipients are among those with the highest risk of influenza infection and complications each year. A few studies show adequate responses after influenza immunization; no studies examined the season-long protection. METHODS: Influenza antibody concentrations were measured using hemagglutination inhibition assays before immunization, 2 to 4 weeks after immunization, and 6 months after immunization in 25 healthy controls and 54 lung transplant patients. Two definitions of seroprotection (40 hemagglutination units (HAU) and 160 HAU which confers about 95% protection) were used. RESULTS: Influenza vaccine responses were high in both groups postimmunization (100% at 40 HAU and 60% healthy and 61% lung transplant at 160 HAU; P = 1.0; chi-square). At 6 months after immunization, seroprotection rates at 40 HAU (95% healthy and 97% lung transplant; P = 1.0) and at 160 HAU (24% healthy and 36% lung transplant; P = 0.40) were observed. CONCLUSION: Seroprotection rates do not differ between healthy and transplant groups over 6 months when 40 HAU or 160 HAU is used. However, the seroprotection rates are disappointingly low when 160 HAU (the antibody concentration associated with 95% protection from infection) is used. Annual influenza vaccine should continue to be a high priority for lung transplant patients.
Subject(s)
Antibodies, Viral/blood , Influenza A Virus, H1N1 Subtype/immunology , Influenza Vaccines/immunology , Influenza, Human/prevention & control , Lung Transplantation , Adult , Aged , Biomarkers/blood , Case-Control Studies , Female , Hemagglutination Inhibition Tests , Humans , Influenza A Virus, H3N2 Subtype/immunology , Influenza Vaccines/administration & dosage , Influenza, Human/blood , Influenza, Human/immunology , Influenza, Human/virology , Lung Transplantation/adverse effects , Male , Middle Aged , Predictive Value of Tests , Seasons , Time Factors , Treatment Outcome , VaccinationABSTRACT
We previously mapped a type 2 diabetes (T2D) locus on chromosome 16 (Chr 16) in an F2 intercross from the BTBR T (+) tf (BTBR) Lep(ob/ob) and C57BL/6 (B6) Lep(ob/ob) mouse strains. Introgression of BTBR Chr 16 into B6 mice resulted in a consomic mouse with reduced fasting plasma insulin and elevated glucose levels. We derived a panel of sub-congenic mice and narrowed the diabetes susceptibility locus to a 1.6 Mb region. Introgression of this 1.6 Mb fragment of the BTBR Chr 16 into lean B6 mice (B6.16(BT36-38)) replicated the phenotypes of the consomic mice. Pancreatic islets from the B6.16(BT36-38) mice were defective in the second phase of the insulin secretion, suggesting that the 1.6 Mb region encodes a regulator of insulin secretion. Within this region, syntaxin-binding protein 5-like (Stxbp5l) or tomosyn-2 was the only gene with an expression difference and a non-synonymous coding single nucleotide polymorphism (SNP) between the B6 and BTBR alleles. Overexpression of the b-tomosyn-2 isoform in the pancreatic ß-cell line, INS1 (832/13), resulted in an inhibition of insulin secretion in response to 3 mM 8-bromo cAMP at 7 mM glucose. In vitro binding experiments showed that tomosyn-2 binds recombinant syntaxin-1A and syntaxin-4, key proteins that are involved in insulin secretion via formation of the SNARE complex. The B6 form of tomosyn-2 is more susceptible to proteasomal degradation than the BTBR form, establishing a functional role for the coding SNP in tomosyn-2. We conclude that tomosyn-2 is the major gene responsible for the T2D Chr 16 quantitative trait locus (QTL) we mapped in our mouse cross. Our findings suggest that tomosyn-2 is a key negative regulator of insulin secretion.
