Galectin-1 and Galectin-3 Expression in Lesional Skin of Patients With Systemic Sclerosis-Association With Disease Severity.

Galectin-1 (Gal-1) and galectin-3 (Gal-3) are carbohydrate-binding proteins involved in normal processes, autoimmunity, and cancer. Increased serum Gal-3 levels in scleroderma were associated with active disease, vasculopathy, and mortality. OBJECTIVES: The aim of this study was to evaluate Gal-1 and Gal-3 expression in the lesional skin of patients with scleroderma regarding disease severity and organ involvement. METHODS: A cross-sectional study was conducted on patients diagnosed as systemic sclerosis (SSc), after informed consent. Clinical and serological profiles were reviewed from medical records. Lesional skin biopsies were taken by losange incision from patients. Samples were analyzed by immunohistochemistry and compared with normal skin of a healthy patient. Parametric statistical analysis was done with Student t test and Pearson coefficient. Significance was established as p ≤ 0.05 with a 95% confidence interval. RESULTS: Biopsies of 10 patients and a healthy control (9 female, 1 male) were analyzed. The mean age was 54.5 years (18-74 years). Four of 10 patients had diffuse, 4 had limited scleroderma, 1 had overlap syndrome, and 1 had sclerodermiform graft-versus-host disease. The mean fibroblasts count per field was 13.2 in scleroderma versus 7.2 in normal skin. The mean expression of Gal-1 in scleroderma fibroblasts was 13% (0%-56%) and 47.5% for Gal-3 (6.5%-95.5%); in normal skin, the mean expression was 91% (90%-95%) for Gal-1 and 97% (89%-100%) for Gal-3. A higher Gal-3 expression in scleroderma (within its lower expression compared with normal skin) was associated with pulmonary artery hypertension (p = 0.004) and to a higher modified Rodnan's skin score (p = 0.0003). In a similar manner, anti-centromere antibodies were associated with a higher Gal-1 expression in SSc skin fibroblasts (p = 0.04). CONCLUSIONS: Gal-1 and Gal-3 had a lower expression in scleroderma lesional skin compared with a normal control. We found a significant correlation between a higher Gal-3 expression (within the lower ones compared with normal skin) in fibroblasts from SSc patients and severe disease (pulmonary hypertension and a higher modified Rodnan's skin score) compared with patients with lower expression of this protein. Similarly, the presence of anti-centromere antibodies was associated with a higher expression of Gal-1 within this group of patients.

MART-1- and gp100-expressing and -non-expressing melanoma cells are equally proliferative in tumors and clonogenic in vitro.

MART-1 and gp100 are prototypical melanoma antigen (Ag), but their clinical use as vaccines or as targets of cytotoxic lymphocytes achieved modest success. Possible explanations could be that as MART-1 and gp100 are melanocyte differentiation Ag, clonogenic Ag-non-expressing cells would be spared by immune effectors, or that clonogenic cells would be intrinsically resistant to cytotoxic lymphocytes. We therefore analyzed the proliferative status of MART-1/gp100-expressing and -non-expressing cells in biopsies, and the clonogenicity and sensitiveness to cytotoxic lymphocytes of the human cutaneous melanoma cell lines MEL-XY1 and MEL-XY3. Analysis of MART-1/gp100 and Ki-67 expression in 22 melanoma tumors revealed that MART-1/gp100-expressing and -non-expressing cells proliferated competitively. MART-1, gp100, tyrosinase, and CD271 expression were studied in MEL-XY1 and MEL-XY3 colonies. At 7 days, colonies displayed positive, negative, and mixed expression patterns. By 14 days, colonies of different sizes developed, showing cells with different clonogenic potential, and Ag were downregulated, suggesting Ag plasticity. Subcloning of MEL-XY1 colonies showed that Ag expression varied with time without interfering with clonogenicity. Finally, clonogenic, MART-1/gp100-expressing cells were lysed by specific CD8 lymphocytes. Thus, MART-1 and gp100 expression and plasticity would not interfere with proliferation or clonogenicity, and clonogenic cells may be lysed by cytotoxic lymphocytes.

Galectin-3 expression correlates with apoptosis of tumor-associated lymphocytes in human melanoma biopsies.

The immune system recognizes diverse melanoma antigens. However, tumors can evade the immune response, therefore growing and progressing. It has been reported that galectin-3 and galectin-1 can induce apoptosis of activated lymphocytes. However, there is strong evidence indicating that the regulation of galectins function in the human tumor microenvironment is a complex process that is influenced by diverse biological circumstances. Here, we have investigated 33 biopsies (eight primary and 25 metastases) from 24 melanoma patients (15-72 years old) and describe the correlation between the expression of galectin-3 or galectin-1 and the level of apoptosis of tumor-associated lymphocytes using immunohistochemistry and an in situ nick translation assay. The range of galectin-3-positive tumor cells varied between 0% and 93% and that of galectin-1-positive tumor cells varied between 5% and 97%. In addition, 23 +/- 27% of tumor-associated lymphocytes were apoptotic. Although our results show a correlation between galectin-3 expression and apoptosis of tumor-associated lymphocytes, we could not find such correlation with galectin-1. Considering the complex process of cancer immunoediting, various interacting factors must be considered.