A pleiotropic effect of the APOE gene: association of APOE polymorphisms with multibacillary leprosy in Han Chinese from Southwest China.

BACKGROUND: Patients with leprosy have a very low risk of Alzheimer disease (AD) and ß-amyloid (Aß) deposition is significantly lower in the brain tissue of elderly patients with leprosy compared with age-matched controls. Apolipoprotein E (ApoE) plays a critical role in lipid metabolic pathways and in the brain, facilitating the proteolytic clearance of Aß. We hypothesized that APOE confers risk of leprosy as lipid metabolism is involved in Mycobacterium leprae infection. OBJECTIVES: To investigate the potential genetic associations between APOE and leprosy in two independent Chinese case-control cohorts from the Yuxi and Wenshan prefectures, Yunnan Province of Southwest China. METHODS: Five APOE single-nucleotide polymorphisms (SNPs) were analysed in 1110 individuals (527 patients and 583 controls) from the Yuxi prefecture using a SNaPshot assay. Genetic variations in the entire APOE exons were screened in 1788 individuals (798 patients and 990 controls) from the Wenshan prefecture using next-generation sequencing technology. RESULTS: The AD-associated SNPs rs405509 and rs439401 increased the risk of leprosy per se and multibacillary leprosy (P < 0·005), but the APOE-ε4 allele did not. The SNPs rs405509 and rs439401 were cis expression quantitative trait loci (eQTL) for APOE expression in human skin. Differential APOE mRNA expression was observed in skin lesions of patients with type I reaction leprosy and those with multibacillary leprosy. APOE and related lipid genes are involved in an interaction network with leprosy susceptibility genes. CONCLUSIONS: The APOE gene is associated with leprosy, most likely by regulating lipid-metabolism-related genes.

Association of the LRRK2 genetic polymorphisms with leprosy in Han Chinese from Southwest China.

Leprosy is a chronic infectious and neurological disease that is caused by infection of Mycobacterium leprae (M. leprae). A recent genome-wide association study indicated a suggestive association of LRRK2 genetic variant rs1873613 with leprosy in Chinese population. To validate this association and further identify potential causal variants of LRRK2 with leprosy, we genotyped 13 LRRK2 variants in 548 leprosy patients and 1078 healthy individuals from Yunnan Province and (re-)analyzed 3225 Han Chinese across China. Variants rs1427267, rs3761863, rs1873613, rs732374 and rs7298930 were significantly associated with leprosy per se and/or paucibacillary leprosy (PB). Haplotype A-G-A-C-A was significantly associated with leprosy per se (P=0.018) and PB (P=0.020). Overexpression of the protective allele (Thr2397) of rs3761863 in HEK293 cells led to a significantly increased nuclear factor of activated T-cells' activity compared with allele Met2397 after lipopolysaccharides stimulation. Allele Thr2397 could attenuate 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine-induced autophagic activity in U251 cells. These data suggest that the protective effect of LRRK2 variant p.M2397T on leprosy might be mediated by increasing immune response and decreasing neurotoxicity after M. leprae loading. Our findings confirm that LRRK2 is a susceptible gene to leprosy in Han Chinese population.

Mapping genetic variants in the CFH gene for association with leprosy in Han Chinese.

Complement factor H (CFH) is an essential regulator in the homeostasis of the complement system that plays multiple roles in leprosy. We previously reported a preliminary association of CFH with leprosy, but potentially causal variants remain to be identified. In this study, we performed a fine-mapping association analysis in 1110 individuals (527 leprosy patients and 583 controls) followed by bioinformatic analyses. We identified no association of typical missense CFH variants with leprosy and factor H-binding protein was not detected in Mycobacterium leprae. However, robust associations (PBonferroni<0.003) of several CFH intronic tag single-nucleotide polymorphisms with leprosy were observed. Expression quantitative trait locus analysis showed that these leprosy-protective alleles were associated with higher CFH level and lower CFHR3 (complement factor H-related 3) level. Our results indicated that CFH variants may contribute to leprosy pathogenesis through altering CFH expression, leading to regulation of complement activity rather than mediating immune evasion by bacteria binding.

[Development of hybridomas secreting monoclonal anti-idiotypic antibodies that bear the internal image of the terminal trisaccharide of PGL-I].

Two hybridomas designated as F7B7 and F7B9 secreting monoclonal anti-idiotypic antibodies against terminal trisaccharide of PGL-I were developed by fusion of SP2/0 cells and spleen cells of BALB/c mouse immunized with mouse monoclonal anti-trisaccharide of PGL-I (MAb1-E10F1). To characterize the F7B7, the following results were obtained. First, F7B7 reacted with MAb1-E10F1 specifically. Secondly, the cross ELISA neutralizing tests gave positive results. The binding of anti-trisaccharide positive serum with trisaccharide (contained in semi-synthetic antigen, NT-O-BSA) was inhibited F7B7 and the degree of inhibition showed dose-dependent manner. The binding of anti-trisaccharide positive serum with F7B7 was inhibited by NT-O-BSA and the degree of inhibition also showed dose-dependent manner. It was concluded that the hybridoma F7B7 is able to secrete monoclonal anti-idiotypic antibodies that bear the internal image of trisaccharide of PGL-I. The potentials and advantages of monoclonal anti-idiotypic antibody F7B7 as surrogate antigen in the serodiagnosis of leprosy have been discussed.

[Production and identification of monoclonal anti-idiotype antibodies against anti-phenolic glycolipid-I antibody of Mycobacterium leprae].

Hybridoma (4C4) secreting monoclone anti-idiotype antibody (McAb2) against anti-phenolic glycolipid-I (PGL-I) antibody (Ab1) was produced by fusion of SP2/0 myeloma cells and spleen cells of syngeneic mice which had been previously tolerant to human IgM 4C4 monoclone anti-idiotype antibody was identified with a series of experiments including competitive and neutralizing inhibition ELISA. It was found that the binding of McAb2 with rabbit anti-PGL-I antibody could be competitively inhibited by NT-O-BSA (synthetic analog of PGL-I) and neutralized by polyclonal anti-PGL-I antibody derived from various origins (human or rabbit); McAb2 could block the binding of purified human Ab1 with NT-O-BSA. The assay of McAb2 as mimic antigen demonstrated that McAb2 could substitute for NT-O-BSA in leprosy serodiagnosis. These results show that anti-idiotype antibody produced by 4C4 is a monoclone anti-idiotype antibody bearing internal image of PGL-I and possibly can be used in leprosy serodiagnosis.

Structure of alpha 2-macroglobulin-protease complexes. Methylamine competition shows that proteases bridge two disulfide-bonded half-molecules.

alpha 2-Macroglobulin (alpha 2M) forms several different covalent complexes with proteases. These include unusual forms in which more than one of the four identical subunits of alpha 2M are cross-linked by amide bonds to more than one lysyl amino group of the bound protease. The structure of these complexes and the question of how the identical subunits are arranged to form two protease binding sites are matters of current controversy. The 185-kDa subunits are arranged into two disulfide-bonded half-molecules which are, in turn, noncovalently associated. We have provided evidence that, in the major multivalent cross-linked form, proteases can span the two half-molecules, forming a covalently bonded tetramer [Wang, D., Yuan, A. I., & Feinman, R. D. (1984) Biochemistry 23, 2807-2811]. An alternative theory has recently been proposed in which the major high molecular weight form has two bonds to protease that are within half-molecules--a multivalent cross-linked dimer [Sottrup-Jensen, L., Hansen, H. F., Pedersen, H. S., & Kristensen, L. (1990) J. Biol. Chem. 265, 17727-17737]. To resolve this conflict, experiments were carried out to determine the structure of one of the high molecular weight bands (band 3) seen on SDS-PAGE. Band 3 has anomalous migration, corresponding to markers of apparent molecular mass of 550 kDa (between the tetramer and dimer). In the experiments described here, reactions of thrombin with alpha 2M were run in the presence of methylamine, which competes for one of the two thrombin-alpha 2M covalent bonds.(ABSTRACT TRUNCATED AT 250 WORDS)