Israel Medical Association Journal

Background: Evaluation of mismatch repair (MMR) deficiency is conducted via immunohistochemistry or by microsatellite instability (MSI) analysis. Heterogeneous immunohistochemistry staining for MMR proteins may show different patterns; however, according to current guidelines, all of those patterns should be interpreted as MMR proficient. This conclusion might lead to false negative results because although most cases of heterogeneity stem from technical factors and biological variability, other types of heterogeneity represent true MMR deficiency.

Objectives: To identify a unique heterogeneity pattern that is associated with true MMR loss.

Methods: We analyzed 145 cases of colorectal carcinoma. Immunohistochemistry staining for MLH1, PMS2, MSH2, and MSH6 were performed. We defined geographic heterogeneity as areas of tumor nuclear staining adjacent to areas of loss of tumor nuclear staining with intact staining in the surrounding stroma. All cases were evaluated for the presence of geographic heterogeneity. In addition, 24 cases were also evaluated by MSI testing.

Results: Of the 145 cases, 24 (16.5%) were MMR deficient. Of the 24 cases for which MSI analysis was also available, 10 cases (41.7%) demonstrated biological heterogeneity, 5 (20.8%) demonstrated technical heterogeneity, and 2 (8.3%) demonstrated geographic heterogeneity. Only the two cases with geographic heterogeneity were MSI-high via MSI analysis. In addition, a germline mutation in MSH-6 was identified in one of these cases.

Conclusions: Geographic heterogeneity may raise a suspicion for a MMR-deficient case, which should be further analyzed using additional methodologies such as MSI analysis.

Background: Although cross-reactions between Epstein-Barr virus (EBV) and human systemic lupus erythematosus (SLE) autoantigens occur, a complete analysis of the potential EBV peptide cross-reactome has not been performed.

Objectives: To analyze the whole EBV proteome searching for peptides common to SLE-related proteins and endowed with an immunological potential.

Methods: Fifty-one SLE-related proteins were analyzed for hexapeptide sharing with EBV proteome using publicly available databases.

Results: An extremely high number of hexapeptides are shared between 34 human SLE autoantigens and EBV proteins. The peptide sharing mostly occurs with complement components C4 and Interleukin-10 (IL-10).

Conclusion: This study thoroughly describes the EBV vs. SLE autoantigens peptide overlap and powerfully supports cross-reactivity as a major mechanism in EBV-associated SLE etiopathogenesis.

Background: Heat shock proteins are highly conserved immunodominant antigens found in various species. Humoral immune responses to mycobacterial HSP65[1] and human HSP60 have been established in a number of human autoimmune diseases.

Objective: To assess the prevalence of antibodies to HSP60 kDa and HSP65 kDa in patients with Sjogren's syndrome as compared to normal subjects.

Methods: Thirty-seven patients with SS[2] were compared with normal controls. The antibodies against human HSP60 were measured by the Anti-Human (IgG/IgM) HSP60 ELISA kit. IgGs[3] and IgMs to mycobacterial HSP65 were determined using an enzyme-linked immunosorbent assay with mycobacterial recombinant HSP65 antigens.

Results: The levels of both anti-HSP60 and -HSP65 were lower among patients compared with controls. IgG autoantibodies to HSP60 were significantly different between groups: 162 ± 55.1 ng/ml in controls versus 112.3 ± 30.6 ng/ml in SS patients (P < 0.001). The levels among controls of anti-HSP65 IgM isotype were also significantly higher than among patients: 111.6 ± 33.4 U/ml versus 96.1 ± 8.9 U/ml (P = 0.01).

Conclusions: The results of the present study show that the levels of different isotypes of anti- HSP60 and HSP65 antibodies were lower in patients with SS than in normal subjects. Additional studies on larger patient populations are required to evaluate the prevalence of these autoantibodies in SS patients.

Background: Food allergies in children are often very serious and can lead to anaphylactic reactions. Observations that camel milk ameliorates allergic reactions were noted over the years. The effect of the camel milk is probably related to its special composition.

Objectives: To investigate the effect of camel milk in several children with severe food (mainly milk) allergies.

Methods: We studied eight children with food allergies who did not benefit from conventional treatment. Their parents, or their physicians, decided to try camel milk as a last resort. The parents were advised by the authors – who have considerable experience with the use of camel milk – regarding how much and when the children should drink the milk. The parents reported daily on the progress of their children.

Results: All eight children in this study reacted well to the milk and recovered fully from their allergies.

Conclusions: These encouraging results should be validated by large-scale clinical trials.

Fanconi anemia is a rare autosomal recessive disorder characterized clinically by congenital abnormalities, progressive bone marrow failure, and a predisposition to malignancy. FA cells are sensitive to DNA cross-linking agents. Complementation analysis of FA cells using somatic cell fusion has facilitated the identification of eight complementation groups, suggesting that FA is a genetically heterogeneous disorder. Six genes (FANCA, FANCC, FANCD2, FANCE, FANGF, FANCG) have been cloned so far. The majority of affected patients belong to FA group A. Of the 32 unrelated Israeli patients with FA that we studied, 6 carried the FANCC mutations and 15 the FANCA mutations. Among the Jewish patients, ethnic-related mutations were common. Recent cumulative evidence suggests that the FA proteins are repair proteins. FANCC, FANCA and FANCG bind and interact in a protein complex found in the cytoplasm and nucleus of normal cells. FANCD2 exists in two isoforms; the long active form, FANCD2-L, is absent from FA cells of all complementation groups. FANCD2 co-localized with BRCA1 in unclear foci, probably as part of a large genomic surveillance complex. Studies using FANCA and FANCC knockout mice suggest that bone marrow precursors express interferon-g hypersensitivity and show progressive apoptosis. The definition of the molecular basis of FA in many affected families now enables prenatal diagnosis.

Between the 1960s and 1980s, the main focus of biological research was nucleic acids and the translation of the coded information into proteins. Protein degradation was a neglected area and regarded by many as a scavenger, non-specific and end process. While it was known that proteins are turning over, the large extent and high specificity of the process - where distinct proteins have half-lives that range from a few minutes to several days - have not been appreciated. The discovery of the lysosome by Dr. Christian de Duve did not change this view significantly, as this organelle is involved mostly in the degradation of extra- and not intracellular proteins, and it was clear that lysosomal proteases, similar to those of the gastrointestinal tract, cannot be substrate specific. The discovery of the complex cascade of the ubiquitin pathway has changed this view dramatically. It is now clear that degradation of cellular proteins is a highly complex, temporally controlled, and tightly regulated process that plays major roles in a broad array of basic pathways during cell life and death. With the multitude of substrates targeted and processes involved, it is not surprising that aberrations in the pathway have been recently implicated in the pathogenesis of many diseases, certain malignancies and neurodegeneration among them. Degradation of a protein via the ubiquitin pathway involves two successive steps: a) conjugation of multiple ubiquitin moieties to the substrate, and b) degradation of the tagged protein by the downstream 263 proteasome complex with release of free and re-utilizable ubiquitin. Despite intensive research, the unknown still exceeds what we currently know on intracellular protein degradation and major key problems remain unsolved. Among these are the modes of specific and timed recognition of the myriad substrates of the system and the nature of the mechanisms that underlie aberrations in the system and pathogenesis of diseases.