Heterogeneity of antibody responses among clinical responders during grass pollen sublingual immunotherapy

BACKGROUND

During allergen-specific sublingual immunotherapy (SLIT), the relevance of changes in specific IgE and IgG antibody titres to treatment efficacy remains to be evaluated at an individual patient level.

OBJECTIVE

To investigate whether antibody responses can be used as biomarkers for SLIT efficacy.

METHODS

Comprehensive quantitative, qualitative and functional analyses of allergen-specific IgA, IgE, IgG1-4 and IgM responses were performed using purified Phl p 1 to 12 allergens in sera, saliva and nasal secretions from 82 grass pollen allergic patients. These patients were enrolled in a randomized, double-blind placebo-controlled study and assessed in an allergen challenge chamber (ClinicalTrials.gov NCT00619827). Antibody responses were monitored in parallel to clinical responses before and after daily sublingual treatment for 4 months with either a grass pollen or a placebo tablet.

RESULTS

A significant mean improvement (i.e. 33-40.6%) in rhinoconjunctivitis total symptom scores was observed in SLIT recipients, irrespective of their baseline patterns of IgE sensitization (i.e. narrow, intermediate, broad) to grass pollen allergens. SLIT did not induce any de novo IgE sensitization. Clinical responders encompassed both immunoreactive patients who exhibited strong increases in titres, affinity and/or blocking activity of grass-pollen-specific IgGs (representing 17% of treated patients), as well as patients with no detectable antibody responses distinguishing them from the placebo group. No significant changes were detected in antibody titres in saliva and nasal washes, even in clinical responders.

CONCLUSIONS AND CLINICAL RELEVANCE

Sublingual immunotherapy with a grass pollen tablet is efficacious irrespective of the patients' baseline sensitization to either single or multiple grass pollen allergens. Seric IgG responses may contribute to SLIT-induced clinical tolerance in a fraction (i.e. 17%) of patients, but additional immune mechanisms are involved in most patients. Consequently, antibody responses cannot be used as a marker of SLIT efficacy at an individual patient level.

[Micro-array based technologies to study the proteome: technological progress and applications]

Since these twenty last years, there is an increasing interest for large-scale analysis of biological function. In the field of transcriptome, the emergence of microarray-based technologies and the design of DNA biochips allow high-throughput studies of RNA expression in cell and tissue at a given moment. In the field of proteome, methods of reference are still the 2D electrophoresis followed by analysis with mass spectrometry. Technological progress makes it possible to apply microarray methods to proteomics study : they are protein biochips or protein arrays. Expression analysis of proteins in a cell or a tissue in simultaneous and highly parallel way give further information for large-scale studies of signaling pathway. Numerous applications of protein microarray-based assays are described in basic biological research and in medical research to identify diagnostic biomarkers of inflammatory and cancerous pathologies and to find out news drugs and new therapeutic targets. This review summarizes concrete applications of microarray-based technology in the field of proteome, describes fundamental technical stages in protein array development and highlights critical points which will be useful to improve this emerging proteomic method.

HLA alleles in relation to specific immunity to liver stage antigen-1 from plasmodium falciparum in Gabon

Cellular responses to synthetic peptides from the Liver Stage Antigen-1 (LSA-1) from Plasmodium falciparum were determined in 229 Gabonese children. HLA class I and II typing (by PCR-SSP and -RFLP, respectively) revealed that HLA-A*19, -B*17 (and -B*70), -DRB1*05, -DQA1*0102, -DQB1*0602 and -DPB1*0402 were the most frequent types or alleles at each locus. The DQB1*0201 and DQB1*0301 alleles were present at a higher frequency among IL-6 and IFN-gamma responders to the LSA-Rep and LSA-CTL peptides, respectively, and a higher proportion of these responders carried A*19 or B*53. The DRB1*06 type was positively related to the IL-10 production in response to the LSA-CTL peptide, and responders presented mainly A*2. The specificity A*10 was negatively associated with the cellular response to the LSA-J peptide. These results suggest a degree of genetic regulation of specific immune responses by HLA-A, operating at the pre-erythrocytic stage of development of P. falciparum in this Central African population.

Evidence for the involvement of both retinoic acid receptor- and retinoic X receptor-dependent signaling pathways in the induction of tissue transglutaminase and apoptosis in the human myeloma cell line RPMI 8226

In this study, we show that both all-trans-retinoic acid (atRA) and 9-cis-retinoic acid (9-cis-RA) are potent inducers of tissue transglutaminase (TGase II), an enzyme involved in apoptosis, at the level of both enzyme activity and mRNA in the human myeloma cell line RPMI 8226. RPMI 8226 cells were shown to express mRNAs for all the retinoid receptors subtypes, ie, RARalpha, RARbeta, RARgamma, RXRalpha, RXRbeta, and RXRgamma. To identify which of these receptors are involved in regulating TGase II expression, several receptor-selective synthetic retinoids were used. Neither CD367, a very potent retinoid that selectively binds and activates receptors of the RAR family, nor CD2425, an RXR-selective agonist, induced TGase II when used alone. However, combination of CD367 and CD2425 resulted in nearly full induction of the enzyme. Moreover, when used in combination with atRA, CD367 partially inhibited the atRA-dependent induction of TGase II, whereas CD2425 enhanced it. The effects of Am 580, CD417, and CD437, three synthetic retinoids selective for the RARs subtypes RARalpha, RARbeta, and RARgamma, respectively, were also investigated. None of these compounds was able to induce TGase II when used alone; however, the combination of each of them with CD2425 resulted in strong induction of the enzyme activity, reaching 30% to 50% of the values obtained in the presence of retinoic acid and suggesting functional redundancy between the RAR subtypes. Finally, treatment with atRA or the combination of CD367 and CD2425, but not with CD367 or CD2425 alone, was also shown to trigger apoptosis in RPMI 8226 cells, with prominent accumulation of TGase II immunoreactivity in apoptotic cells. Taken together these data suggest that the induction of TGase II expression and apoptosis in the RPMI 8226 myeloma cell line required ligand-dependent activation of both the RAR and RXR receptors.

Association of rheumatoid arthritis with an amino acid allelic variation of the T cell receptor

OBJECTIVE

To investigate allelic variations of T cell receptor residues for a contribution to rheumatoid arthritis (RA) susceptibility.

METHODS

We conducted an RA case-control study involving 1,579 northwest Europeans: 766 patients with erosive and rheumatoid factor-positive disease and 813 control subjects. Productive changes of segments TCRAV6S1, TCRAV7S1, TCRAV8S1, TCRAV10S2, and TCRBV6S1, TCRBV6S7 were investigated by single-strand conformation polymorphisms. The TCRAV8S1 association was confirmed by restriction fragment length polymorphism.

RESULTS

In the systematic study (77 patients and 119 controls), an increase in 1 TCRAV8S1 genotype was found in the RA patients (P = 0.0004). This finding was replicated in 2 further populations, one from France (212 patients and 254 controls) and the other from Britain (477 patients and 440 controls), with a similar odds ratio (OR), which allowed pooling of the data and confirmation of the association (OR 1.3 [95% confidence interval 1.1-1.7], P = 0.008).

CONCLUSION

These findings show evidence that TCRA is an RA susceptibility locus.

Association of HLA class II genes with susceptibility to Crohn's disease

BACKGROUND

Published studies on the association between HLA class II genes and inflammatory bowel disease are contradictory perhaps because of the limited size and ethnic heterogeneity of the populations studied.

AIM

To compare the frequencies of HLA class II genes in a large number of French patients with Crohn's disease and in an ethnically matched control group.

METHODS

344 patients (196 F, 148 M, mean age 23.6 years) with Crohn's disease were molecularly genotyped for the HLA-DQB1 and DRB1 alleles. The results were compared with those for an ethnically matched control population of 488 white adults.

RESULTS

There were two significant variations of alleles at the DQB1 locus: an increase in DQB1*0501 allele frequency (chi 2 = 10.6, corrected p value (pc) = 0.01, odds ratio (OR) = 1.61) and a decrease in DQB1*0602/0603 allele frequencies (chi 2 = 8.43, pc = 0.037, OR = 0.66). DRB1 analysis showed associations with three allelic variations: an increase in the frequencies of DRB1*01 (chi 2 = 12.86, pc = 0.003, OR = 1.75) and DRB1*07 alleles (chi 2 = 11.18, pc = 0.008, OR = 1.58) and a very significant decrease in that of the DRB1*03 allele (chi 2 = 19.7, pc = 9.10(-5), OR = 0.46).

CONCLUSION

The alleles DRB1*01 and DRB1*07 are associated with susceptibility to Crohn's disease. The strong negative association between the DRB1*03 allele and Crohn's disease suggests that the HLA-DRB1*03 allele mediates 'resistance' to Crohn's disease.

Multiple DNA variant association analysis: application to the insulin gene region in type I diabetes

Association and linkage studies have shown that at least one of the genetic factors involved in susceptibility to insulin-dependent diabetes mellitus (IDDM) is contained within a 4.1-kb region of the insulin gene. Sequence analysis has led to the identification of 10 DNA variants in this region that are associated with increased risk for IDDM. These variants are in strong linkage disequilibrium with each other, and previous studies have failed to distinguish between the variant(s) that cause increased susceptibility to IDDM and others that are associated with the disease because of linkage disequilibrium. To address this problem, we have undertaken a large population study of French diabetics and controls and have analyzed genotype patterns for several of the variant sites simultaneously. This has led to the identification of a subset consisting of four variants (-2733AC, -23HphI, -365VNTR, and +1140AC), at least one of which appears to be directly implicated in disease susceptibility. The multiple-DNA-variant association-analysis approach that is applied here to the problem of identifying potential susceptibility variants in IDDM is likely to be important in studies of many other multifactorial diseases.

Binding of RU486 and deacylcortivazol to the glucocorticoid receptor is insensitive to sulfhydryl-modifying agents

The differential sensitivity of the rat liver glucocorticoid receptor (GR) to sulfhydryl group modifying agents when bound to various agonist and antagonist ligands was studied. [3H]Triamcinolone acetonide (TA) binding was completely abolished by previous treatment of the unbound receptor with various N-alkylmaleimides. On the contrary, [3H]RU486 binding was only slightly affected by treatment with N-ethylmaleimide (NEM) and more significantly decreased with maleimides bearing bulky substituents. Ligand exchange experiments demonstrated that, unlike the agonist TA, the antiglucocorticoid RU486 was unable to protect the GR binding site from the effect of NEM. This lack of protection would seem to be due to the presence of the bulky 11 beta-substituent in RU486 since RU26988 and RU28362, two 11 beta hydroxylated glucocorticoids bearing the same 17 alpha-propynyl side chain as RU486 but lacking the 11 beta-substituent could protect GR against NEM. The ability of a GR ligand to prevent NEM inactivation of TA binding appeared unrelated to its agonist or antagonist nature: deacylcortivazol, a potent agonist, afforded no protection whereas antagonists of the 17 beta-carboxamide series did. These data strongly suggest that compounds bearing bulky substituents on the steroid A and/or C rings, like deacylcortivazol and RU486, are positioned differently from canonical glucocorticoids in the steroid binding groove of the GR.

Steroid receptor exchange assay in the presence of acetonitrile: application to the study of glucocorticoid- and anti-glucocorticoid-receptor complexes

Acetonitrile was used to modify the binding parameters of glucocorticoid-receptor complexes. Acetonitrile (8%) caused a striking increase of the rate constant of dissociation of non-transformed [3H]triamcinolone and [3H]RU 486 receptor complexes. The latter complexes appeared significantly less sensitive to acetonitrile than the former. Similar data were obtained for heat-transformed [3H]triamcinolone and RU 486-receptor complexes purified at a 90% relative homogeneity by DEAE-Trisacryl (diethylaminoethyl) chromatography. The rate constant of dissociation of both steroid-receptor complexes decreased after transformation. The dissociation of non-transformed receptor complexes by acetonitrile was reversible, and an exchange assay allowing 75% to 85% steroid exchange is described. However, the dissociation of transformed receptor complexes appeared completely irreversible and precluded the design of any exchange assay.