Plasma soluble Fas ligand concentration: decrease in elderly men and increase in patients with gastric carcinoma

sFasL-The Key to a Riddle: Immune Responses in Aging Lung and Disease

By dint of the aging population and further deepened with the Covid-19 pandemic, lung disease has turned out to be a major cause of worldwide morbidity and mortality. The condition is exacerbated when the immune system further attacks the healthy, rather than the diseased, tissue within the lung. Governed by unremittingly proliferating mesenchymal cells and increased collagen deposition, if inflammation persists, as frequently occurs in aging lungs, the tissue develops tumors and/or turns into scars (fibrosis), with limited regenerative capacity and organ failure. Fas ligand (FasL, a ligand of the Fas cell death receptor) is a key factor in the regulation of these processes. FasL is primarily found in two forms: full length (membrane, or mFasL) and cleaved (soluble, or sFasL). We and others found that T-cells expressing the mFasL retain autoimmune surveillance that controls mesenchymal, as well as tumor cell accumulation following an inflammatory response. However, mesenchymal cells from fibrotic lungs, tumor cells, or cells from immune-privileged sites, resist FasL⁺ T-cell-induced cell death. The mechanisms involved are a counterattack of immune cells by FasL, by releasing a soluble form of FasL that competes with the membrane version, and inhibits their cell death, promoting cell survival. This review focuses on understanding the previously unrecognized role of FasL, and in particular its soluble form, sFasL, in the serum of aged subjects, and its association with the evolution of lung disease, paving the way to new methods of diagnosis and treatment.

Declining Physical Performance Associates with Serum FasL, miR-21, and miR-146a in Aging Sprinters

Aging is associated with systemic inflammation and cellular apoptosis accelerating physiological dysfunctions. Whether physically active way of life affects these associations is unclear. This study measured the levels of serum inflammatory and apoptotic molecules, their change over 10 years, and their associations with physical performance in sprint-trained male athletes. HsCRP, cell counts, HGB, FasL, miR-21, and miR-146a were measured cross-sectionally (n = 67, 18–90 yrs) and serum FasL, miR-21, and miR-146a and their aging-related associations with physical performance were assessed over a 10-year follow-up (n = 49, 50–90 yrs). The cross-sectional study showed positive age correlations for neutrophils and negative for lymphocytes, red blood cells, HGB, FasL, and miR-146a. During the 10-year follow-up, FasL decreased (P = 0.017) and miR-21 (P < 0.001) and miR-146a (P = 0.005) levels increased. When combining the molecule levels, aging, and physical performance, FasL associated with countermovement jump and bench press (P < 0.001), miR-21 and miR-146a with knee flexion (P = 0.023; P < 0.001), and bench press (P = 0.004; P < 0.001) and miR-146a with sprint performance (P < 0.001). The studied serum molecules changed in an age-dependent manner and were associated with declining physical performance. They have potential as biomarkers of aging-related processes influencing the development of physiological dysfunctions. Further research is needed focusing on the origins and targets of circulating microRNAs to clarify their function in various tissues with aging.

The role of CD95 and CD95 ligand in cancer

CD95 (Fas/APO-1) and its ligand, CD95L, have long been viewed as a death receptor/death ligand system that mediates apoptosis induction to maintain immune homeostasis. In addition, these molecules are important in the immune elimination of virus-infected cells and cancer cells. CD95L was, therefore, considered to be useful for cancer therapy. However, major side effects have precluded its systemic use. During the last 10 years, it has been recognized that CD95 and CD95L have multiple cancer-relevant nonapoptotic and tumor-promoting activities. CD95 and CD95L were discovered to be critical survival factors for cancer cells, and were found to protect and promote cancer stem cells. We now discuss five different ways in which inhibiting or eliminating CD95L, rather than augmenting, may be beneficial for cancer therapy alone or in combination with standard chemotherapy or immune therapy.

Soluble Fas might serve as a diagnostic tool for gastric adenocarcinoma

BACKGROUND

Fas (Apo-1/CD95) and its specific ligand (FasL) are key elements in apoptosis. They have been studied in different malignancies but there are few published studies about the soluble forms of these markers (i.e. sFas/sFasL) in gastric cancer. We have compared the serum levels of sFas/sFasL in gastric adenocarcinoma patients and cases with pre-neoplastic lesions as potential markers for early diagnosis, and investigated their relation with clinicopathological characteristics.

METHODS

Fifty-nine newly-diagnosed cases of gastric adenocarcinoma who had undergone gastrectomy, along with 62 endoscopically- and histologically-confirmed non-cancer individuals were enrolled in this study. sFas/sFasL serum levels were detected by Enzyme Linked Immunosurbent Assay.

RESULTS

Mean serum sFas level was significantly higher in gastric cancer patients than in control group (305.97 +/- 63.71 (pg/ml) vs. 92.98 +/- 4.95 (pg/ml), P < 0.001); while the mean serum level of sFasL was lower in patients with gastric adenocarcinoma (0.138 +/- 0.04 (pg/ml) vs. 0.150 +/- 0.02 (pg/ml), P < 0.001). Mean serum levels of sFas/sFasL were significantly different in both intestinal/diffuse and cardiac/non-cardiac subtypes when compared to the control group (P < 0.001). There was an increase in the serum level of sFas from the first steps of pre-neoplastic lesions to gastric adenocarcinoma (P < 0.001). Patients who had no lymph node involvement (N0) showed significantly higher serum levels of sFas compared to others (P = 0.044).

CONCLUSIONS

Production of sFas may play a critical role in the carcinogenesis of intestinal-type gastric cancer. sFas serum level may serve as a non-invasive tool for early diagnosis of gastric cancer.

Serum markers of apoptosis decrease with age and cancer stage

The physical manifestations of aging reflect a loss of homeostasis that effects molecular, cellular and organ system functional capacity. As a sentinel homeostatic pathway, changes in apoptosis can have pathophysiological consequences in both aging and disease. To assess baseline global apoptosis balance, sera from 204 clinically normal subjects had levels of sFas (inhibitor of apoptosis), sFasL (stimulator of apoptosis), and total cytochrome c (released from cells during apoptosis) measured. Serum levels of sFas were significantly higher while sFasL and cytochrome c levels were lower in men compared to women. With increasing age there was a decrease in apoptotic markers (cytochrome c) and pro-apoptotic factors (sFasL) and an increase in anti-apoptotic factors (sFas) in circulation. The observed gender differences are consistent with the known differences between genders in mortality and morbidity. In a separate cohort, subjects with either breast (n = 66) or prostate cancer (n = 38) exhibited significantly elevated sFas with reduced sFasL and total cytochrome c regardless of age. These markers correlated with disease severity consistent with tumor subversion of apoptosis. The shift toward less global apoptosis with increasing age in normal subjects is consistent with increased incidence of diseases whose pathophysiology involves apoptosis dysregulation.

Circulating levels of soluble Fas ligand in cachexic patients with COPD are higher than those in non-cachexic patients with COPD

OBJECTIVE

Apoptosis may be involved in the pathophysiology of cachexia in patients with chronic obstructive pulmonary disease (COPD). The purpose of this study is to assess the potential role of the Fas-Fas ligand (FasL) system in cachexic patients with COPD.

PATIENTS AND METHODS

We measured the circulating levels of soluble FasL (sFasL), with a newly developed, highly sensitive enzyme-linked immunosorbent assay system in seventy patients with COPD and forty-seven control subjects.

RESULTS

The levels of sFasL in the COPD patients were significantly lower than those in the control subjects (46+/-29 vs. 55+/-28 pg/ml; p<0.05), whereas the levels of soluble Fas (sFas) remained unchanged between the two groups. The significant correlation between the levels of sFasL and sFas, observed in the control subjects (r=0.304; p<0.05), was absent in the COPD patients. Cachexic COPD patients with a relatively lower BMI (BMI <20 kg/m(2), n=45) and %fat (%fat <20%, n=34), showed significantly increased levels of sFasL compared to non-cachexic COPD patients with a relatively higher BMI (BMI > or =20 kg/m(2), n=25) and %fat (%fat > or =20%, n=36) (BMI; 51+/-33 vs. 36+/-15 pg/ml; p<0.05. %fat; 55+/-33 vs. 37+/-21 pg/ml; p<0.01), due to the inverse relationships between the body composition measurements and the levels of sFasL observed exclusively in the patients (BMI; r=-0.307; p<0.05. %fat; r=-0.283; p<0.05).

CONCLUSION

These results may suggest that the Fas-FasL system does not play a significant role in the potential triggers of enhanced apoptosis leading to skeletal muscle wasting and adipose tissue depletion in cachexic patients with COPD.

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