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Biomedical subjects

Abraham Mittelman

Publications and source records attributed to Abraham Mittelman.

At least 19 recordsLinked to original sources
PubMed2006

Preliminary data on Pemphigus vulgaris treatment by a proteomics-defined peptide: a case report.

BACKGROUND: Although described by Hippocrates in 400 B.C., pemphigus disease still needs a safe therapeutical approach, given that the currently used therapies (i.e. corticosteroids and immunosuppressive drugs) often provoke collateral effects. Here we present preliminary data on the possible use of a proteomics derived desmoglein peptide which appears promising in halting disease progression without adverse effects. METHODS: The low-similarity Dsg349-60REWVKFAKPCRE peptide was topically applied for 1 wk onto a lesion in a patient with a late-stage Pemphigus vulgaris (PV) complicated by diabetes and cataract disease. The peptide was applied as an adjuvant in combination with the standard corticosteroid-based immunosuppressive treatment. RESULTS: After 1 wk, the treated PV eroded lesion appeared dimensionally reduced and with an increased rate of re-epithelization when compared to adjacent non-treated lesions. Short-term benefits were: decrease of anti-Dsg antibody titer and reduction of the corticosteroid dosage. Long-term benefits: after two years following the unique 1-wk topical treatment, the decrease of anti-Dsg antibody titer persists. The patient is still at the low cortisone dosage. Adverse effects: no adverse effect could be monitored. CONCLUSION: With the limits inherent to any preliminary study, this case report indicates that topical treatment with Dsg349-60REWVKFAKPCRE peptide may represent a feasible first step in the search for a simple, effective and safe treatment of PV.

Journal Article↗
PubMed2006

Proteomic definition of a desmoglein linear determinant common to Pemphigus vulgaris and Pemphigus foliaceous.

BACKGROUND: A number of autoimmune diseases have been clinically and pathologically characterized. In contrast, target antigens have been identified only in a few cases and, in these few cases, the knowledge of the exact epitopic antigenic sequence is still lacking. Thus the major objective of current work in the autoimmunity field is the identification of the epitopic sequences that are related to autoimmune reactions. Our labs propose that autoantigen peptide epitopes able to evoke humoral (auto)immune response are defined by the sequence similarity to the host proteome. The underlying scientific rationale is that antigen peptides acquire immunoreactivity in the context of their proteomic similarity level. Sequences uniquely owned by a protein will have high potential to evoke an immune reaction, whereas motifs with high proteomic redundancy should be immunogenically silenced by the tolerance phenomenon. The relationship between sequence redundancy and peptide immunoreactivity has been successfully validated in a number of experimental models. Here the hypothesis has been applied to pemphigus diseases and the corresponding desmoglein autoantigens. METHODS: Desmoglein 3 sequence similarity analysis to the human proteome followed by dot-blot/NMR immunoassays were carried out to identify and validate possible epitopic sequences. RESULTS: Computational analysis led to identifying a linear immunodominant desmoglein-3 epitope highly reactive with the sera from Pemphigus vulgaris as well as Pemphigus foliaceous. The epitopic peptide corresponded to the amino acid REWVKFAKPCRE sequence, was located in the extreme N-terminal region (residues 49 to 60), and had low redundancy to the human proteome. Sequence alignment showed that human desmoglein 1 and 3 share the REW-KFAK-RE sequence as a common motif with 75% residue identity. CONCLUSION: This study 1) validates sequence redundancy to autoproteome as a main factor in shaping desmoglein peptide immunogenicity; 2) offers a molecular mechanicistic basis in analyzing the commonality of autoimmune responses exhibited by the two forms of pemphigus; 3) indicates possible peptide-immunotherapeutical approaches for pemphigus diseases.

Journal Article↗
PubMed2006

Synthetic dimer of indole-3-carbinol: second generation diet derived anti-cancer agent in hormone sensitive prostate cancer.

BACKGROUND: Cruciferous vegetables have been found to have anti-prostate cancer effects. The active compounds mediating these effects include indoles such as indole-3-carbinol (I3C) and isothiocyanates. I3C is unstable having tissue tropic effects and clinical utility has been partly addressed by the synthesis of a more stable dimer diindolylmethane (DIM). METHODS: Anti-proliferative activity was measured by XTT assay and cytosolic proteins quantitated by Western blot analysis. RESULTS: DIM (IC(50) 50 microM) is a better anti-proliferative agent than I3C (IC(50) 150 microM) in androgen dependent LNCaP cells, inhibits DNA synthesis, and growth of R1881 stimulated LNCaP cells. Androgen receptor (AR), cyclin D1, and cdk4, induced by R1881, are downregulated by DIM. DIM downregulates phosphorylated Akt and phosphatidyl inositol 3-kinase and downstream inhibition of cyclin D1 and cdk4. CONCLUSION: These studies provide evidence that DIM is a second-generation chemopreventive agent with a viable cellular target and has clinical potential as an anti-prostate cancer chemopreventive.

Androgens↗
PubMed2005

3,3'-Diindolylmethane downregulates pro-survival pathway in hormone independent prostate cancer.

Epidemiological evidences suggest that the progression and promotion of prostate cancer (CaP) can be modulated by diet. Since all men die with prostate cancer rather than of the disease, it is of particular interest to prevent or delay the progression of the disease by chemopreventive strategies. We have been studying the anticancer properties of compounds present in cruciferous vegetables such as indole-3-carbinol (I3C). Diindolylmethane (DIM) is a dimer of I3C that is formed under acidic conditions and unlike I3C is more stable with higher anti-cancer effects. In the present report, we demonstrate that DIM is a potent anti-proliferative agent compared to I3C in the hormone independent DU 145 CaP cells. The anti-prostate cancer effect is mediated by the inhibition of the Akt signal transduction pathway as DIM, in sharp contrast to I3C, induces the downregulation of Akt, p-Akt, and PI3 kinase. DIM also induced a G1 arrest in DU 145 cells by flow cytometry and downstream concurrent inhibition of cell cycle parameters such as cyclin D1, cdk4, and cdk6. Our data suggest a need for further development of DIM, as a chemopreventive agent for CaP, which justifies epidemiological evidences and molecular targets that are determinants for CaP dissemination/progression. The ingestion of DIM may benefit CaP patients and reduce disease recurrence by eliminating micro-metastases that may be present in patients who undergo radical prostatectomy.

Androgens↗
PubMed2005

Proteomic scan for tyrosinase peptide antigenic pattern in vitiligo and melanoma: role of sequence similarity and HLA-DR1 affinity.

Immune responses contribute to the pathogenesis of vitiligo and target melanoma sometimes associated with vitiligo-like depigmentation in some melanoma patients. We analyzed the sera from patients with vitiligo and cutaneous melanoma for reactivity toward tyrosinase peptide sequences 1) endowed with low level of similarity to human proteome, and 2) potentially able to bind HLA-DR1 Ags. We report that the tyrosinase autoantigen was immunorecognized with the same molecular pattern by sera from vitiligo and melanoma patients. Five autoantigen peptides composed the immunodominant anti-tyrosinase response: aa95-104FMGFNCGNCK; aa175-182 LFVWMHYY; aa176-190FVWMHYYVSMDALLG; aa222-236IQKLTGDENFTIPYW, and aa233-247 IPYWDWRDAEKCDIC. All of the five antigenic peptides were characterized by being (or containing) a sequence with low similarity level to the self proteome. Sera from healthy subjects were responsive to aa95-104FMGFNCGNCK, aa222-236IQKLTGDENFTIPYW, and aa233-247 IPYWDWRDAEKCDIC, but did not react with the aa175-182LFVWMHYY and aa176-190FVWMHYYVSMDALLG peptide sequences containing the copper-binding His180 and the oculocutaneous albinism I-A variant position F176. Our results indicate a clear-cut link between peptide immunogenicity and low similarity level of the corresponding amino acid sequence, and are an example of a comparative analysis that might allow to comprehensively distinguish the epitopic peptide sequences within a disease from those associated to natural autoantibodies. In particular, these data, for the first time, delineate the linear B epitope pattern on tyrosinase autoantigen and provide definitive evidence of humoral immune responses against tyrosinase.

Alleles↗
PubMed2005

Differences in glycosylation patterns of heat shock protein, gp96: implications for prostate cancer prevention.

Heat shock protein gp96 induces a tumor-specific protective immunity in a variety of experimental tumor models. Because the primary sequences of the glycoprotein, gp96 are identical between tumor and normal tissues, the peptides associated with gp96 and/or the posttranslational modifications of gp96, determine its immunogenicity. Gp96-associated peptides constitute the antigenic repertoire of the source tissue; thus, purified gp96-peptide complexes have clinical significance as autologous cancer vaccines. However, the role of altered glycosylation and its contribution in the biological as well as immunologic activity of gp96 still remains uncharacterized. We examined the cancer-specific glycosylation patterns of gp96. To this end, monosaccharide compositions of gp96 were compared between normal rat prostate and two cancerous rat prostate tissues, nonmetastatic/androgen-dependent Dunning G and metastatic/androgen-independent MAT-LyLu, as well as two human nonmetastatic prostate cancer cell lines, androgen-dependent LnCaP and androgen-independent DU145. Marked differences were observed between the gp96 monosaccharide compositions of the normal and cancerous tissues. Furthermore, gp96 molecules from more aggressive cellular transformations were found to carry decreasing quantities of several monosaccharides as well as sum total content of neutral and amino sugars. We believe that the unique glycosylation patterns contribute to cellular phenotype and that the posttranslational modifications of gp96 may affect its functional attributes.

Animals↗
PubMed2005

Aging-associated changes in gene expression in the ACI rat prostate: Implications for carcinogenesis.

BACKGROUND: Prostate cancer is the most frequently diagnosed neoplasm and the second leading cause of cancer-related mortality in men. Although the incidence of prostate cancer increases with age, the link between aging and prostate cancer is poorly understood. METHODS: Affymetrix oligonucleotide microarrays were used to analyze the mRNA expression levels in the dorsolateral prostates from 6- and 18-month-old ACI rats. Real-time RT-PCR and immunohistochemistry was performed to validate microarray data in a select set of genes. RESULTS: Microarray analysis revealed changes in gene expression associated with inflammation, oxidative stress, tissue remodeling, and energy metabolism. Most of these changes have been related to increased proliferative status of the prostate, anti-apoptosis, activated stroma, and alteration of the energy metabolism. CONCLUSIONS: Age-associated alterations in the gene expression profile may put the aging prostate in risk for the initiation, promotion, and progression of neoplastic transformation in both our animal model and humans.

Aging↗
PubMed2005

Definition of anti-tyrosinase MAb T311 linear determinant by proteome-based similarity analysis.

Using non-self discrimination as a driving force in generating peptide immunogenicity, we have developed a computer-assisted proteomic analysis in order to identify the protein antigenic regions that have evoked humoral response. The purpose of this study was to further validate the computational analysis for melanoma-associated antigens and, at the same time, to assess the efficacy of the methodology in defining antigenic regions of autoantigens associated to autoimmune diseases. To achieve this two-fold objective, we have examined the enzyme tyrosinase, a protein that represents an important autoantigen in patients with vitiligo or melanoma. Here, we report that the antigenic linear determinant of the monoclonal antibody (Mab) T311 raised against the melanoma/vitiligo tyrosinase autoantigen is located in the low similarity 15-mer amino acid sequence tyrosinase 233-247 IPYWDWRDAEKCDIC, within the fragment 237-247. These data confirm non-similarity to the host proteome as a factor that participates in shaping peptide immune reactivity and may be a first step towards designing tyrosinase antigenic peptides to be used for (i) direct neutralization of harmful melanocytes-attacking autoantibodies in vitiligo, or (ii) production of antibodies against tyrosinase-positive melanomas. Moreover tyrosinase peptide antigens might be used as key tools in studying the boundaries between self-tolerance and autoimmunity phenomena.

Amino Acid Sequence↗
PubMed2005

Characterization of polyclonal antibodies raised against a linear peptide determinant of desmoglein-3.

Our labs are pursueing the goal of exactly defining the qualities of peptide antigenicity, immunogenicity and pathogenicity in order to develop safe specific immunotherapies by utilizing specific portions of disease-associated-proteins (DAPs). Using as a model the Pemphigus vulgaris antigen (PVA) desmoglein 3 (Dsg3), we have studied the murine humoral response against the Dsg3 amino acid 49-60 peptide sequence, previously characterized as sequence having low similarity to the mouse proteome. The results show that the low-similarity Dsg3(49-60)REWVKFAKPCRE peptide does not elicit pathogenic antibodies.

Animals↗
PubMed2005

Gene therapy in cancer: the missing point.

Over the last century cancer research has produced data leading to a composite picture where gene mutations and epigenetic phenomena strictly relate and overlap. This complexity has repercussions on the anti-cancer therapeutical strategies. The therapeutic pathway paved by the kochian one-cause/one disease principle fails in front of a multigenic multiphenomena disease like cancer. We still do not know what target(s) to hit/modify in order to prevent/stop the carcinogenic progression. On the light of cancer statistics 2005, we discuss the need of exactly defining the cancer targets in order to exploit the high potential of gene therapy.

Chromosome Aberrations↗
PubMed2004

Epitope definition by proteomic similarity analysis: identification of the linear determinant of the anti-Dsg3 MAb 5H10.

BACKGROUND: Walking along disease-associated protein sequences in the search for specific segments able to induce cellular immune response may direct clinical research towards effective peptide-based vaccines. To this aim, we are studying the targets of the immune response in autoimmune diseases by applying the principle of non-self-discrimination as a driving concept in the identification of the autoimmunogenic peptide sequences. METHODS: Computer-assisted proteomic analysis of the autoantigen protein sequence and dot-blot/NMR immunoassays are applied to the prediction and subsequent validation of the epitopic sequences. RESULTS: Using the experimental model Pemphigus vulgaris/desmoglein 3, we have identified the antigenic linear determinant recognized by MAb 5H10, a monoclonal antibody raised against the extracellular domain of human desmoglein-3. The computer-assisted search for the Dsg3 epitope was conducted by analyzing the similarity level to the mouse proteome of the human desmoglein protein sequence. Dot-blot immunoassay analyses mapped the epitope within the sequence Dsg349-60 REWVKFAKPCRE, which shows low similarity to the mouse proteome. NMR spectroscopy analyses confirmed the specificity of MAb 5H10 for the predicted epitope. CONCLUSIONS: This report promotes the concept that low level of sequence similarity to the host's proteome may modulate peptide epitopicity.

Journal Article↗
PubMed2004

Non-self-discrimination as a driving concept in the identification of an immunodominant HMW-MAA epitopic peptide sequence by autoantibodies from melanoma cancer patients.

We analyzed the sera of patients with melanoma to define the human humoral autoantibody profile towards HMW-MAA. Computational proteome scanning using the non-self-discrimination principle as a guide led to the individuation of the low-similarity HMW-MAA781-789RATVWMLRL peptide fragment as an immunodominant B-cell epitope. Linear B-cell determinant individuation was experimentally validated by dot blot immunoassay and NMR spectroscopy analysis. Regulation of physiologic self-reactivity by the non-self-discrimination principle is discussed.

Antigens, Neoplasm↗
PubMed2004

NMR probing of in silico identification of anti-HPV16 E7 mAb linear peptide epitope.

A proteomics-based approach was exploited in order to individuate peptide sequences having the immunogenic potential to evoke humoral response. The epitope search utilized two parameters: the similarity level of the peptide sequence to the host's proteins, and the peptide capability to bind to the major histocompatibility complex class II molecules. By this approach, the human papillomavirus 16 E7(49-63) RAHYNIVTFCCKCDS peptide was individuated as the immunogenic epitope recognized by an anti-HPV16 E7 monoclonal antibody raised against the full-length viral oncoprotein. In this report, two-dimensional nuclear magnetic resonance spectroscopic experiments unequivocally probe the HPV16 E7 epitope individuation.

Amino Acid Sequence↗
PubMed2004

Computational peptide dissection of Melan-a/MART-1 oncoprotein antigenicity.

We have mapped the linear antigenic determinant of a commercial MAb raised in the mouse against the melanoma-associated-antigen Melan-A/MART-1. The B cell epitope on the Melan-A/MART-1 oncoprotein is located in the 15-mer amino acid sequence 101-115 PPAYEKLSAEQSPPP, within residues 102-106. The definition of the antigenic sequence on Melan-A/MART-1 oncoprotein was reached following analyses of MHC II binding potential and similarity level to the mouse proteome, that put into evidence the 15-mer amino acid sequence 101-115 PPAYEKLSAEQSPPP as the top scoring peptide in binding H2-A(d) molecules and the epitopic sequence residues 102-106 (i.e., the peptide sequence PAYEK) as having low-similarity level to the mouse proteome. Dot-blot epitope mapping immunoassay identified proline residue 102 as critical, based on its effect on antibody recognition. The present study adds to previous companion reports in validating the hypothesis that low-similarity to the host's proteome and binding potential to MHC II molecules are essential concurring factors in the modulation of the pool of epitopic sequences.

Amino Acid Sequence↗
PubMed2004

Identification of monoclonal anti-HMW-MAA antibody linear peptide epitope by proteomic database mining.

An efficient strategy is presented for the identification of antigenic sequences in the context of given MHC molecules of interest. The proteomic analysis of the antigenic peptide repertoire is described and demonstrated by using high-molecular weight melanoma-associated antigen. The identification of the epitopic sequence of a monoclonal antibody raised against the 250 kDa tumor associated antigen was reached by using only seven short synthetic peptide fragments, instead of the 155 non-overlapping 15-mer peptides theoretically necessary as minimum screening library. The present result has been obtained by applying as driving criteria the analysis of the peptide affinity to MHC class II molecules and the non-self discrimination concept.

Amino Acid Sequence↗
PubMed2003

Role of MHC II affinity and molecular mimicry in defining anti-HER-2/neu MAb-3 linear peptide epitope.

With the aid of computational biology, we have studied the possibility of predicting the peptides able to evoke humoral immune response by using as experimental model the human HER-2/neu breast cancer-associated antigen. We already demonstrated that HER-2/neu peptides, that are the target of humoral human and mouse immune responses, correspond to those sequences having a low degree of sequence similarity to host's proteome. Here we report that the linear peptide determinant of the anti-HER-2/neu MAb-3 is characterized by a low degree of sequence similarity to mouse proteome in combination with high binding potential to specific MHC II molecule.

Amino Acid Sequence↗
PubMed2002

Monoclonal and polyclonal humoral immune response to EC HER-2/NEU peptides with low similarity to the host's proteome.

We are studying peptide immunogenicity as a function of the similarity level to the host's proteome. By using as a model the breast/prostate cancer-associated HER-2/neu antigen, we analyzed the monoclonal and polyclonal humoral immune responses against HER-2/neu peptide motifs not shared with the host proteome. We show here that (i) a mouse monoclonal antibody (MAb) raised against the extracellular domain (EC) of human HER-2/neu oncoprotein recognized a linear peptide motif endowed with low similarity level to the mouse proteome; (ii) likewise, human sera from breast/prostate cancer patients preferentially recognized peptide fragments from the EC of the HER-2/neu oncoprotein having sequences that are not present in the human proteome. Together with previous results obtained in other disease models (cervical cancer-associated HPV16 E7 oncoprotein and Pemphigus vulgaris auto-antigen desmoglein-3), the present data suggest that a low level of sequence similarity to the host's proteome might be an important factor in shaping the pool of B cell epitopes.

Animals↗