Underexpression and overexpression of Fas and Fas ligand: a double-edged sword

Correlations between histopathologic findings, serum biomarker levels, and clinical outcomes in Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN)

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are severe dermatological emergencies. The role of cytokines and chemokines in the pathogenesis, progression of the disease, and histopathologic features is not fully elucidated. To address this gap, we conducted a retrospective study examining the associations between 42 serum biomarkers, histopathologic findings, and clinical outcomes in SJS/TEN patients. We reviewed the medical records of 23 patients diagnosed with SJS/TEN. Regarding histopathology, our study did not reveal any significant associations between the degree of epidermal necrosis, dermal mononuclear cell infiltration, and clinical outcomes. However, an intriguing observation was made regarding the degree of dermal infiltration of CD8 + cells, which showed a negative correlation with the severity of acute ocular complications. Notably, serum levels of IFN-γ positively correlated with the number of CD8 + cells in dermal infiltration. Additionally, higher serum levels of myeloperoxidase were associated with greater degrees of epidermal necrosis, while serum Fas ligand and stem cell factor levels were elevated in individuals with increased dermal mononuclear cell infiltration. Furthermore, the levels of S100A8/A9 were significantly correlated with the SCORTEN and mortality rate. These findings provide insights into the intricate pathogenesis of the disease.

Responsiveness to i.v. immunoglobulin therapy in patients with toxic epidermal necrolysis: A novel pharmaco-immunogenetic concept

Toxic epidermal necrolysis (TEN) represents a rare drug-induced autoimmune reaction with delayed-type hypersensitivity that initiates the process of developing massive keratinocyte apoptosis, dominantly in the dermoepidermal junction. Although the etiopathophysiology has not yet been fully elucidated, the binding of Fas ligand (FasL, CD95L) to the Fas receptor (CD95) was shown to play a key role in the induction of apoptosis in this syndrome. The knowledge of the role of immunoglobulin G (IgG) in inhibition of Fas-mediated apoptosis contributed to the introduction of i.v. Ig (IVIg) in the therapy of TEN patients. Despite great enthusiasm for this therapy at the end of the 1990s, subsequent studies in various populations and meta-analyses could not unequivocally confirm the efficacy of the IVIg-based treatment concept. Today, therefore, we are faced with the dilemmas of how to adjust therapy of TEN patients most effectively, which patients could benefit from IVIg therapy and what dose of the preparation should be administrated. The ground-breaking question is: do the host genetic profiles influence the responsiveness and side-effects of IVIg therapy in TEN patients? Based on recent pharmacological, immunological and genetic findings, we suggest that the variability of IVIg therapy outcomes in TEN patients may be related to functional variants in Fas, FasL and Fc-γ receptor genes. This novel concept could lead to improved quality of care for patients with TEN, facilitating personalized therapy to reduce mortality.

The role of hepatic sinusoidal obstruction in the pathogenesis of the hepatic involvement in HELLP syndrome: Exploring the literature

AIM

This study aims to determine, based on existing data, whether the mechanism resulting in liver dysfunction in HELLP syndrome resembles that in Sinusoidal Obstruction Syndrome (SOS).

BACKGROUND

HELLP syndrome is a serious pregnancy disorder with high maternal and perinatal morbidity and mortality rates. Because of poor insight in its pathophysiology, particularly that of the liver involvement, clinical management is limited to symptomatic treatment, often followed by termination of pregnancy. SOS is a rare, potentially life-threatening complication of radio and/ or chemotherapy in the preparation of hematopoietic cell transplantation. The etiology of liver dysfunction in SOS is - unlike that in HELLP syndrome - better-understood and seems to be initiated by direct toxic damage and demise of endothelial cells, causing hepatic sinusoidal obstruction and ischemia.

METHODS

We searched Pubmed, Embase and Cochrane for reports on the etiology of HELLP and SOS. This yielded 73 articles, with 14 additional reports from the references listed in these articles.

RESULTS

The dysfunctional placenta in women developing HELLP initiates a cascade of events that eventually results in liver dysfunction. The placenta releases, besides anti-angiogenetic factors, also necrotic debris and cell-free DNA, a mixture that not only induces systemic endothelial dysfunction as in preeclampsia, but also a systemic inflammatory response. The latter aggravates the endothelio-toxic effects in the systemic cardiovascular bed, amplifying the already increased pro-thrombotic conditions. Particularly in microcirculations with extremely low shear forces, such as in the hepatic sinusoids, this will facilitate microthrombi formation and fibrin deposition eventually resulting in obstruction of the sinusoids similar as in SOS. The latter causes ischemic damage and progressive demise of hepatocytes.

CONCLUSION

The available information supports the concept that the liver damage in HELLP and SOS results from sinusoidal ischemia, presumably resulting from partially overlapping pathophysiological mechanisms.

Single-Nucleotide Polymorphisms of FAS and FASL Genes and Risk of Idiopathic Aplastic Anemia

FAS/FASL signaling system plays a vital role in the regulation of apoptosis, envisaged as a death process required for immune surveillance to prevent autoimmunity and tumorigenesis along with several other biological activities. Several single-nucleotide polymorphisms (SNPs) of FAS/FASL system can result in aberrant apoptosis, which can cause different cancers and autoimmune diseases. Aplastic anemia (AA) is an autoimmune dysfunction characterized by peripheral blood pancytopenia associated with hypoplasia of bone marrow. The aim of this study was to screen Pakistani AA patients and controls for two Fas SNPs rs2234767 and rs1800682 and two FASLG SNPs rs763110 and rs5030772. Genotyping of 392 DNA samples was done by Tetra-ARMS polymerase chain reaction. Genotypic frequencies of Fas rs1800682 and FASLG rs5030772 showed significance difference in their distribution in both controls and patients, while Fas rs2234767 and FASLG rs763110 SNPs had no such difference. Carriers of rs1800682 AG+GG had a very odd ratio of 4.63, with 95% confidence interval (CI) of 3.01-7.11, while individuals with FASLG rs5030772 AG+GG were more common in controls than patients with OR 0.53 and 95% CI of 0.34-0.83. Cumulative effects of these SNPs were analyzed, and they showed almost similar trends; however, Fas rs2234767 and FASLG rs763110 genotypes in combination with Fas rs1800682 and FASLG rs5030772 demonstrated significant association. This study provided information that endorsed the involvement of FAS/FASL system SNPs in the pathogenesis of AA; further studies should be designed to understand the exact role of SNPs that can help in early diagnosis and treatment.

FASL rs763110 polymorphism contributes to cancer risk: an updated meta-analysis involving 43,295 subjects

Background

Published studies investigating the association between genetic polymorphism -884C/T (rs763110) of the FAS ligand (FASL) promoter and cancer risk reported inconclusive results. To derive a more precise estimation of the relationship, we performed an updated meta-analysis of all eligible studies.

Methodology/Principal Findings

We carried out a meta-analysis, including 47 studies with 19,810 cases and 23,485 controls, to confirm a more conclusive association between the FASL rs763110 polymorphism and cancer susceptibility. Overall, significantly reduced cancer risk was associated with the variant -884T when all studies were pooled (TC vs. CC: OR = 0.83, 95%CI = 0.75–0.92; P_{heterogeneity}<0.001; TT+TC vs. CC: OR = 0.85, 95%CI = 0.77–0.94; P_{heterogeneity}<0.001). Stratified analysis revealed that there was a statistically reduced cancer risk in Asians (TC vs. CC: OR = 0.76, 95%CI = 0.67–0.87; P_{heterogeneity}<0.001; TT+TC vs. CC: OR = 0.79, 95%CI = 0.70–0.90; P_{heterogeneity}<0.001) and in patients with cancers of head and neck (TC vs. CC: OR = 0.87, 95%CI = 0.77–0.99; P_{heterogeneity} = 0.118; TT+TC vs. CC: OR = 0.88, 95%CI = 0.78–0.99; P_{heterogeneity} = 0.168) and ovarian cancer (TC vs. CC: OR = 0.67, 95%CI = 0.49–0.90; P_{heterogeneity} = 0.187; TT+TC vs. CC: OR = 0.64, 95%CI = 0.48–0.86; P_{heterogeneity} = 0.199). Meta-regression showed that ethnicity (p = 0.029) and genotyping method (p = 0.043) but not cancer types (p = 0.772), sample size (p = 0.518), or source of controls (p = 0.826) were the source of heterogeneity in heterozygote comparison.

Conclusion

Our results suggest that the FASL polymorphism rs763110 is associated with a significantly reduced risk of cancer, especially in Asian populations.

Distinct and overlapping genomic profiles and antiviral effects of Interferon-λ and -α on HCV-infected and noninfected hepatoma cells

Recently, several SNPs in the region of the IL28B (IFN-λ) gene have been associated with spontaneous clearance of hepatitis C virus (HCV) and enhanced cure rates for IFN-alfa-based therapies, suggesting a potential correlation between IFN-λ and the ability to clear HCV. To understand the mechanism of IFN-λ's as compared to IFN-α's antiviral activity, we performed a comprehensive analysis of their anti-HCV effects, whole genome transcriptome profiling with validation, and signalling of IFN-α and IFN-λ using J6/JFH-1 and Huh7.5 cells in vitro. IFN-λ and IFN-α exhibited comparable anti-HCV activity and gene expression profiles in Huh7.5 cells. While the majority of genes induced by IFN-α and IFN-λ were similar, IFN-λ exhibits profound, but delayed kinetics of IFN-stimulated genes (ISG) induction, while IFN-α induced more rapid induction of ISGs. Furthermore, the increased induction of ISG expression by IFN-λ correlated with up-regulation of IFN-λ receptor (IL-28RA) expression and more prolonged activation of the Jak-STAT signalling pathway. The findings from our comparative analysis of IFN-α and IFN-λ in HCV-infected and noninfected cells support the clinical use of IFN-λ as a potential alternative to IFN-α in the treatment of chronic hepatitis C.

Short-term lenalidomide (Revlimid) administration ameliorates cardiomyocyte contractile dysfunction in ob/ob obese mice

Lenalidomide is a potent immunomodulatory agent capable of downregulating proinflammatory cytokines such as tumor necrosis factor-α (TNF-α) and upregulating anti-inflammatory cytokines. Lenalidomide has been shown to elicit cardiovascular effects, although its impact on cardiac function remains obscure. This study was designed to examine the effect of lenalidomide on cardiac contractile function in ob/ob obese mice. C57BL lean and ob/ob obese mice were given lenalidomide (50 mg/kg/day, p.o.) for 3 days. Body fat composition was assessed by dual-energy X-ray absorptiometry. Cardiomyocyte contractile and intracellular Ca(2+) properties were evaluated. Expression of TNF-α, interleukin-6 (IL-6), Fas, Fas ligand (FasL), the short-chain fatty acid receptor GPR41, the NFκB regulator IκB, endoplasmic reticulum (ER) stress, the apoptotic protein markers Bax, Bcl-2, caspase-8, tBid, cytosolic cytochrome C, and caspase-12; and the stress signaling molecules p38 and extracellular signal-regulated kinase (ERK) were evaluated by western blot. ob/ob mice displayed elevated serum TNF-α and IL-6 levels, fat composition and glucose intolerance, the effects of which except glucose intolerance and fat composition were attenuated by lenalidomide. Cardiomyocytes from ob/ob mice exhibited depressed peak shortening (PS) and maximal velocity of shortening/relengthening, prolonged time-to-PS and time-to-90% relengthening as well as intracellular Ca(2+) mishandling, which were ablated by lenalidomide. Western blot analysis revealed elevated levels of TNF-α, IL-6, Fas, Bip, Bax, caspase-8, tBid, cleaved caspase-3 caspase-12, cytochrome C, phosphorylation of p38, and ERK in ob/ob mouse hearts, the effects of which with the exception of Bip, Bax, and caspase-12 were alleviated by lenalidomide. Taken together, these data suggest that lenalidomide is protective against obesity-induced cardiomyopathy possibly through antagonism of cytokine/Fas-induced activation of stress signaling and apoptosis.

The role of T cell apoptosis in nervous system autoimmunity

Fas is a transmembrane receptor involved in the death program of several cell lines, including T lymphocytes. Deleterious mutations hitting genes involved in the Fas pathway cause the autoimmune lymphoprolipherative syndrome (ALPS). Moreover, defective Fas function is involved in the development of common autoimmune diseases, including autoimmune syndromes hitting the nervous system, such as multiple sclerosis (MS) and chronic inflammatory demyelinating polyneuropathy (CIDP). In this review, we first explore some peculiar aspects of Fas mediated apoptosis in the central versus peripheral nervous system (CNS, PNS); thereafter, we analyze what is currently known on the role of T cell apoptosis in both MS and CIDP, which, in this regard, may be seen as two faces of the same coin. In fact, we show that, in both diseases, defective Fas mediated apoptosis plays a crucial role favoring disease development and its chronic evolution.

Polymorphisms of the FAS and FASL genes and risk of breast cancer

FAS and its ligand FASL are crucial in apoptotic cell death. Loss of FAS and gain of aberrant FASL expression are common features of malignant transformation. This study was designed to investigate whether the functional polymorphisms of FAS -1377G/A (rs2234767) and FASL -844T/C (rs763110) affect the risk of developing breast cancer. Genotypes were analyzed by a polymerase chain reaction-restriction fragment length polymorphism assay in 436 breast cancer patients and 496 healthy controls. In this study, as compared to the wild-type homozygote and heterozygote, the distribution of the FAS -1377GG, GA and AA genotypes among breast cancer patients were significantly different from those among healthy controls (P=0.011), with the AA genotype being more prevalent among patients than the controls (P=0.003). Similarly, the frequencies of the FASL -844TT, TC and CC genotypes also significantly differed among breast cancer patients and healthy controls (P<0.001), with the CC genotype being significantly over-represented in breast cancer patients compared with the controls (P<0.001). In the unconditional logistic regression model following adjustment for age, the subjects carrying the FAS -1377AA genotype had a 1.75-fold increased risk [95% confidence interval (CI), 1.13-2.69] for development of breast cancer compared with patients carrying the GG genotype. Similarly, in the recessive model, the FASL -844CC genotype significantly increased the risk of breast cancer with an odds ratio (OR) of 1.92 (95% CI 1.46-2.54) compared with the TT or TT + TC genotypes. Our results suggest that functional polymorphisms in the death pathway genes FAS and FASL significantly contribute to the occurrence of breast cancer.