Alberta Lucchese

Computer-assisted analysis of molecular mimicry between human papillomavirus 16 E7 oncoprotein and human protein sequences

The immunology of human papillomavirus (HPV) infections has peculiar characteristics. The long latency for cervical cancer development after primary viral infection suggests mechanisms that may aid the virus in avoiding the host immunosurveillance and establishing persistent infections. In order to understand whether molecular mimicry phenomena might explain the ability of HPV to avoid a protective immune response by the host cell, sequence similarity between HPV16 E7 oncoprotein and human self‐proteins was examined by computer‐assisted analysis. Data were obtained showing that the HPV16 E7 protein has high and widespread similarity to several human proteins involved in a number of critical regulatory processes. In addition, multiple identical and different E7 peptide motifs are present in the same human protein. Thus, sharing of common motifs between viral oncoproteins and molecules of normal cells may be one cause underlying the scarce immunogenicity of HPV infections. The hypothesis is advanced that synthetic peptides harbouring viral motifs not and/or scarcely represented in the hosts cellular proteins may represent a valuable immunotherapeutic approach for cervical cancer treatment.

Oral lichen planus: update on etiopathogenesis, diagnosis and treatment

Lichen planus is an inflammatory mucocutaneous disorder. Skin, oral and genital mucosal surfaces, scalp, and nails can be affected. Its development is chronic, with a possible malignant degeneration. Spontaneous remission is rare. Although the etiology of oral lichen planus is still unclear, there is evidence that it is a complex immunologic disease mediated by cytotoxic cells directed against basilar keratinocytes and resulting in vacuolar degeneration and lysis of basal cells. In long-standing, atrophic and erosive forms, the treatment is usually aimed at relieving pain and may include immunosuppressive agents, especially corticosteroid, topical cyclosporin, or tacrolimus, topical and systemic retinoids. However, the use of these drugs may be accompanied by several side effects. For this reason clinicians, currently, have focused their attention to new biological agents which provide selective immunological results with less side effects than generic immunosupressants.

Molecular mimicry of phage displayed peptides mimicking GD3 ganglioside

We have analyzed sequence homologies between nonimmunogenic phage displayed peptides mimicking GD3 ganglioside and human/mouse self-proteins. The GD3 ganglioside phagotopes showed homology to proteins involved in carbohydrate metabolism/transport. Besides this expected homology, molecular mimicry of critical regulatory proteins was found. These data contribute to our understanding of the structural relatedness of antigenic determinants defined by specific anti-GD3 monoclonal antibodies and, in addition, suggest that molecular mimicry might explain the nonimmunogenicity of these peptides otherwise characterized by specificity to the mAb counterpart. We conclude that construction of peptides harboring motifs absent or scarcely represented in endogenous self-proteins might be a useful approach in melanoma immunotherapy.

Use of Lugol’s iodine in oral cancer diagnosis: An overview

Early diagnosis of oral squamous cell carcinoma (OSCC) still represents an important challenge for clinicians and patients. Vital staining such as toluidine blue and Lugols iodine solution, are routinely used in the OSCC detection but few data exist about the last one. A literature review is made to evaluate the effectiveness and safety of Lugols iodine solution in OSCC detection and in its margins demarcation. A review was made of the studies published between 1990 and 2010 in relation to the application of Lugols iodine for OSCC detection and a better definition of its margins. Data obtained point to the utility and the safety of Lugols iodine when employed for detection and margins delineation of OSCC and dysplasia. All the studies consulted found the Lugols iodine to be effective, cheap and easy to use and they emphasized its importance in clinical practice. There is need for larger controlled, randomized studies with carefully selected and standardized outcome measures and patients.

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 hosts 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 hosts proteome might be an important factor in shaping the pool of B cell epitopes.

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.

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 hosts proteome and binding potential to MHC II molecules are essential concurring factors in the modulation of the pool of epitopic sequences.

Clinical effectiveness of palifermin in prevention and treatment of oral mucositis in children with acute lymphoblastic leukaemia: a case–control study

The aim of this study was to evaluate the efficacy of palifermin, an N-terminal truncated version of endogenous keratinocyte growth factor, in the control of oral mucositis during antiblastic therapy. Twenty patients undergoing allogeneic stem-cell transplantation for acute lymphoblastic leukaemia were treated with palifermin, and compared to a control group with the same number of subjects and similar inclusion criteria. Statistical analysis were performed to compare the outcomes in the treatment vs. control groups. In the treatment group, we found a statistically significant reduction in the duration of parenteral nutrition (P=0.002), duration of mucositis (P=0.003) and the average grade of mucositis (P=0.03). The statistical analysis showed that the drug was able to decrease the severity of mucositis. These data, although preliminary, suggest that palifermin could be a valid therapeutic adjuvant to improve the quality of life of patients suffering from leukaemia.

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

BackgroundWalking 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.MethodsComputer-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.ResultsUsing 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.ConclusionsThis report promotes the concept that low level of sequence similarity to the hosts proteome may modulate peptide epitopicity.

Correlating low-similarity peptide sequences and HIV B-cell epitopes

Although a large number of human immunodeficiency virus-1 (HIV-1) derived B-cell epitopes has been experimentally identified, the structural requirements underlying HIV humoral immune response remain unknown. Here, we review the current literature on HIV B-cell epitopes as catalogued in the www.hiv.lanl.gov/content/immunology website, searching for common structural and/or functional immunogenic motifs. The analysis of HIV antibody data documents that the linear determinants recognized by human or murine humoral immune responses, are (or harbor) pentapeptide fragments with no or only very low similarity to the respective host proteome. The present literature analysis provides relevant insights that may be applied to design anti-HCV therapeutic approaches exempt from autoimmune collateral effects.