Anti-Hsp20 antibody concentrations inversely correlated with tumor progression in ovarian cancer.

PURPOSE: To investigate the serum concentrations of anti-heat shock protein 20 (anti-Hsp20) antibodies in women with ovarian cancer at different clinical stages, and the relationship between these concentrations and tumor progression. MATERIALS AND METHODS: Blood samples were obtained from 72 patients undergoing surgery for ovarian cancer, 21 women with ovarian carcinoid, and 42 healthy women. Anti-Hsp20 antibody concentrations were determined by enzyme-linked immunosorbent assay. RESULTS: Mean anti-Hsp20 antibody concentrations were significantly lower in patients with ovarian cancer than in the control group. The anti-Hsp20 antibody concentrations were negatively correlated with ovarian cancer malignancy. CONCLUSIONS: The present findings suggest that anti-Hsp20 antibodies may play a protective role against ovarian cancer progression, and that anti-Hsp20 antibodies may be a new index for the early diagnosis and treatment of ovarian cancer.

A Neospora caninum vaccine using recombinant proteins fails to prevent foetal infection in pregnant cattle after experimental intravenous challenge.

The aim of the present study was to evaluate the immunogenicity and protective efficacy of rNcSAG1, rNcHSP20 and rNcGRA7 recombinant proteins formulated with immune stimulating complexes (ISCOMs) in pregnant heifers against vertical transmission of Neospora caninum. Twelve pregnant heifers were divided into 3 groups of 4 heifers each, receiving different formulations before mating. Immunogens were administered twice subcutaneously: group A animals were inoculated with three recombinant proteins (rNcSAG1, rNcHSP20, rNcGRA7) formulated with ISCOMs; group B animals received ISCOM-MATRIX (without antigen) and group C received sterile phosphate-buffered saline (PBS) only. The recombinant proteins were expressed in Escherichia coli and purified nickel resin. All groups were intravenously challenged with the NC-1 strain of N. caninum at Day 70 of gestation and dams slaughtered at week 17 of the experiment. Heifers from group A developed specific antibodies against rNcSAG1, rNcHSP20 and rNcGRA7 prior to the challenge. Following immunization, an statistically significant increase of antibodies against rNcSAG1 and rNcHSP20 in all animals of group A was detected compared to animals in groups B and C at weeks 5, 13 and 16 (P<0.001). Levels of antibodies against rNcGRA7 were statistical higher in group A animals when compared with groups B and C at weeks 5 and 16 (P>0.001). There were no differences in IFN-γ production among the experimental groups at any time point (P>0.05). Transplacental transmission was determined in all foetuses of groups A, B and C by Western blot, immunohistochemistry and nested PCR. This work showed that rNcSAG1, rNcHSP20 and rNcGRA7 proteins while immunogenic in cattle failed to prevent the foetal infection in pregnant cattle challenged at Day 70 of gestation.

Rabbit antibodies against Toxoplasma Hsp20 are able to reduce parasite invasion and gliding motility in Toxoplasma gondii and parasite invasion in Neospora caninum.

Toxoplasma gondii Hsp20 is a pellicle-associated functional chaperone whose biological role is still unknown. Hsp20 is present in different apicomplexan parasites, showing a high degree of conservation across the phylum, with Neospora caninum Hsp20 presenting an 82% identity to that of T. gondii. Hence rabbit anti-T. gondii Hsp20 serum was able to recognize the N. caninum counterpart. Interestingly, both N. caninum and T. gondii Hsp20 localized to the inner membrane complex and to the plasma membrane. Incubation of T. gondii and N. caninum tachyzoites with an anti-TgHsp20 serum reduced parasite invasion at rates of 57.23% and 54.7%, respectively. This anti-serum also reduced T. gondii gliding 48.7%. Together, all this data support a role for Hsp20 in parasite invasion and gliding motility.

Favourable prognostic value of antibodies anti-HSP20 in patients with cystic echinococcosis: a differential immunoproteomic approach.

Seeking biomarkers reflecting disease development in cystic echinococcosis (CE), we used a proteomic approach linked to immunological characterisation for the identification of respective antigens. Two-dimensional gel electrophoresis (2-DE) of sheep hydatid fluid, followed by immunoblot analysis (IB) with sera from patients with distinct phases of disease, enabled us to identify by mass spectrometry heat shock protein 20 (HSP20) as a potential marker of active CE. Using IB, antibodies specific to the 34 kDa band of HSP20 were detected in sera from 61/95 (64%) patients with CE, but not in sera from healthy subjects. IB revealed anti-HSP20 antibodies in a higher percentage of sera from patients with active disease than in sera from patients with inactive disease (81 vs. 24%; P = 10(-4)). These primary results were confirmed in a long-term follow-up study after pharmacological and surgical treatment. Herewith anti-HSP20 antibody levels significantly decreased over the course of treatment in sera from patients with cured disease, relative to sera from patients with progressive disease (P = 0·017). Thus, during CE, a comprehensive strategy of proteomic identification combined with immunological validation represents a promising approach for the identification of biomarkers useful for the prognostic assessment of treatment of CE patients.

Evaluation of the antigenic value of recombinant Toxoplasma gondii HSP20 to detect specific immunoglobulin G antibodies in Toxoplasma infected humans.

Recombinant Toxoplasma gondii small heat shock protein HSP20, surface antigen SAG1 and dense granule GRA7 were analyzed by IgG-ELISA with serum samples of Toxoplasma infected humans grouped as I (IgG+, IgM+), II (IgG+, IgM-) and III (IgG-, IgM-). rHSP20 reacted against 80% and 62.5% of serum samples from groups I and II, respectively. rSAG1 was recognized by 85% of the samples from group I and 70.8% from group II, whereas rGRA7 was recognized by 85% and 66.6% of the serum samples from groups I and II, respectively. When a combination of two or three recombinant antigens was used, the sensitivity values improved to 85-95% for group I and 87.5-91.7% for group II. All combinations tested produced similar reactivity profiles. None of the recombinant proteins reacted against group III serum samples. In conclusion, we demonstrated that T. gondii HSP20 elicits an important B-cell response during human infection, and could be suitable for the development of serodiagnosis tools.

The Leishmania HSP20 is antigenic during natural infections, but, as DNA vaccine, it does not protect BALB/c mice against experimental L. amazonensis infection.

Protozoa of the genus Leishmania are causative agents of leishmaniasis, an important health problem in both human and veterinary medicine. Here, we describe a new heat shock protein (HSP) in Leishmania, belonging to the small HSP (sHSP) family in kinetoplastids. The protein is highly conserved in different Leishmania species, showing instead significant divergence with sHSP's from other organisms. The humoral response elicited against this protein during Leishmania infection has been investigated in natural infected humans and dogs, and in experimentally infected hamsters. Leishmania HSP20 is a prominent antigen for canine hosts; on the contrary, the protein seems to be a poor antigen for human immune system. Time-course analysis of appearance of anti-HSP20 antibodies in golden hamsters indicated that these antibodies are produced at late stages of the infection, when clinical symptoms of disease are patent. Finally, the protective efficacy of HSP20 was assessed in mice using a DNA vaccine approach prior to challenge with Leishmania amazonensis.

Babesia divergens: identification and characterization of BdHSP-20, a small heat shock protein.

This study describes the identification and characterization of the Babesia divergens alpha-crystallin/small heat shock protein 20 (BdHSP-20). BdHSP-20 was recognized by the DG7 monoclonal antibody (DG7 mAb) originally produced by Precigout et al. [Precigout, E., Valentin, A., Carcy, B., Gorenflot, A., Nakamura, K., Aikawa, M., Schrevel, J. 1993. Babesia divergens: characterization of a 17-kDa merozoite membrane protein. Experimental Parasitology 77, 425-434] against B. divergens merozoites. We used DG7 mAb to immunoscreen a B. divergens cDNA library to clone the gene encoding the small heat shock protein. Bdhsp-20 is a single copy gene interrupted by one intron. The deduced gene product (BdHSP-20) clearly belongs to the alpha-crystallin family and shows significant homology to Babesia bovis, Plasmodium falciparum and Toxoplasma gondii sHSPs, with the highest degree of sequence identity around the catalytic domain. Nutritient stress (serum depletion) treatment of the parasites induced the upregulation of BdHSP-20 gene expression observed by semi-quantitative PCR and immunoprecipitation. This regulation pattern suggests that BdHSP-20 could probably be of importance for parasite survival in the case of environmental stress. BdHSP-20 has previously been shown to be highly conserved among different strains and antibodies against the protein drastically reduce parasitemia in vitro.

Toxoplasma gondii Hsp20 is a stripe-arranged chaperone-like protein associated with the outer leaflet of the inner membrane complex.

BACKGROUND INFORMATION: Toxoplasma gondii is among the most successful parasites, with nearly half of the human population chronically infected. T. gondii has five sHsps [small Hsps (heat-shock proteins)] located in different subcellular compartments. Among them, Hsp20 showed to be localized at the periphery of the parasite body. sHsps are widespread, constituting the most poorly conserved family of molecular chaperones. The presence of sHsps in membrane structures is unusual. RESULTS: The localization of Hsp20 was further analysed using high-resolution fluorescent light microscopy as well as electron microscopy, which revealed that Hsp20 is associated with the outer surface of the IMC (inner membrane complex), in a set of discontinuous stripes following the same spiralling trajectories as the subpellicular microtubules. The detergent extraction profile of Hsp20 was similar to that of GAP45 [45 kDa GAP (gliding-associated protein)], a glideosome protein associated with the IMC, but was different from that of IMC1 protein. Although we were unable to detect interacting protein partners of Hsp20 either in normal or stressed tachyzoites, an interaction of Hsp20 with phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate phospholipids could be observed. CONCLUSIONS: Hsp20 was shown to be associated with a specialized membranous structure of the parasite, the IMC. This discontinuous striped-arrangement is unique in T. gondii, indicating that the topology of the outer leaflet of the IMC is not homogeneous.

Differential subcellular localization of members of the Toxoplasma gondii small heat shock protein family.

The results of this study describe the identification and characterization of the Toxoplasma gondii alpha-crystallin/small heat shock protein (sHsp) family. By database (www.toxodb.org) search, five parasite sHsps (Hsp20, Hsp21, Hsp28, Hsp29, and the previously characterized Hsp30/Bag1) were identified. As expected, they share the homologous alpha-crystallin domain, which is the key characteristic of sHsps. However, the N-terminal segment of each protein contains unique characteristics in size and sequence. Most T. gondii sHsps are constitutively expressed in tachyzoites and fully differentiated bradyzoites, with the exception of Hsp30/Bag1. Interestingly, by subcellular localization we observed that T. gondii sHsps are located in different compartments. Hsp20 is located at the apical end of the cell, Hsp28 is located inside the mitochondrion, Hsp29 showed a membrane-associated labeling, and Hsp21 appeared throughout the cytosol of the parasites. These particular differences in the immunostaining patterns suggest that their targets and functions might be different.