Chemical chaperones curcumin and 4-phenylbutyric acid improve secretion of mutant factor H R127H by fibroblasts from a factor H-deficient patient.

Factor H (FH) is one of the most important regulatory proteins of the alternative pathway of the complement system. Patients with FH deficiency have a higher risk for development of infections and kidney diseases because of the uncontrolled activation and subsequent depletion of the central regulatory component C3 of the complement system. In this study, we investigated the consequences of the Arg(127)His mutation in FH (FH(R127H)) previously described in an FH-deficient patient, on the secretion of this protein by skin fibroblasts in vitro. We observed that, although the patient cells stimulated with IFN-γ were able to synthesize FH(R127H), the mutant protein was largely retained within the endoplasmic reticulum (ER), whereas normal human fibroblasts stimulated with IFN-γ secrete FH without retention in the ER. Moreover, the retention of FH(R127H) provoked enlargement of ER cisterns after treatment with IFN-γ. A similar ER retention was observed in Cos-7 cells expressing the mutant FH(R127H) protein. Despite this deficiency in secretion, we show that the FH(R127H) mutant is capable of functioning as a cofactor in the Factor I-mediated cleavage of C3. We then evaluated whether a treatment could increase the secretion of FH, and observed that the patient's fibroblasts treated with the chemical chaperones 4-phenylbutiric acid or curcumin increased the secretion rate of FH. We propose that these chemical chaperones could be used as alternative therapeutic agents to increase FH plasma levels in FH-deficient patients caused by secretion delay of this regulatory protein.

Carrier potential properties of Bacillus thuringiensis Cry1A toxins for a diphtheria toxin epitope.

The N-terminal half or toxic fragment of Bacillus thuringiensis Cry proteins is comprised of three structural domains. In a previous paper, we showed that this region plays an important role in the immunogenicity of the B. thuringiensis Cry proteins. Due to this ability and along with their stability it is worthy of investigating whether this region has carrier potential. To approach this, an eight amino acid hydrophobic motif in alpha-helix 7 of wild-type (WT) Cry1A toxins was exchanged for a diphtheria toxin epitope (DTB). The resultant recombinant toxins were tested for their ability to induce specific anti-Cry and anti-diphtheria toxin antibodies in mice after intraperitoneal and nasal immunization. We found that recombinant Cry1A toxins retained their ability to induce serum and mucosal anti-Cry Ab as well as IgG subclasses, although with a varied magnitude. By the systemic route, the effect of the amino acid substitution in the ratio of the IgG1/IgG2a Ab, leading in some sites toward IgG1 or IgG2a is more evident. Interestingly, mice produced specific anti-DTB IgG, and IgA after intranasal immunization. Together, our results support and show the immunogenic properties of the WT Cry1A toxins as well as its carrier potential for a DTB.

Pemphigus foliaceus and desmoglein 1 gene polymorphism: is there any relationship?

Transmembrane proteins of the cadherin superfamily, the desmogleins and desmocollins, mediate intercellular adhesion in desmosomes. Autoantibodies to desmoglein 1 (dsg1) are a hallmark of pemphigus foliaceus (PF), a disease characterized by skin blistering resulting from keratinocyte cell detachment. The etiology and pathogenesis of this disease remain poorly understood; however, genetic susceptibility is clearly involved. The aim of this study was to verify if genetic variants of dsg1 influence susceptibility/resistance to endemic PF (fogo selvagem). Two single nucleotide polymorphisms (SNPs) were analyzed: 809 (C,T), a synonymous variation, and 1660 (A,C), a tyrosine<-->serine variation in the fifth extracellular domain. Allelic, haplotypic and genotypic frequencies did not differ significantly between the patient (n=134) and the control (n=227) population samples. Moreover, there is no evidence of interaction between the DSG1 and the HLA-DRB1 and IL6 genes, whose alleles had been found associated with differential susceptibility to PF. The results of this study agree with the described and predicted B- and T-cell epitopes of the dsg1 molecule, which seemingly are not affected by the allelic variation. We conclude that genetic diversity of the autoantigen dsg1 is not a major factor for PF pathogenesis in the Brazilian population.