Early-onset autoimmunity associated with SOCS1 haploinsufficiency.

Autoimmunity can occur when a checkpoint of self-tolerance fails. The study of familial autoimmune diseases can reveal pathophysiological mechanisms involved in more common autoimmune diseases. Here, by whole-exome/genome sequencing we identify heterozygous, autosomal-dominant, germline loss-of-function mutations in the SOCS1 gene in ten patients from five unrelated families with early onset autoimmune manifestations. The intracellular protein SOCS1 is known to downregulate cytokine signaling by inhibiting the JAK-STAT pathway. Accordingly, patient-derived lymphocytes exhibit increased STAT activation in vitro in response to interferon-γ, IL-2 and IL-4 that is reverted by the JAK1/JAK2 inhibitor ruxolitinib. This effect is associated with a series of in vitro and in vivo immune abnormalities consistent with lymphocyte hyperactivity. Hence, SOCS1 haploinsufficiency causes a dominantly inherited predisposition to early onset autoimmune diseases related to cytokine hypersensitivity of immune cells.

Suppressor of cytokine signaling 1 (SOCS1) silencing and Hep-2 sensitizing dendritic cell vaccine in laryngocarcinoma immunotherapy.

OBJECTIVE: Many studies have recently suggested that dendritic cell (DC) vaccine contributes to the immunotherapy of various types of human tumors. It has been proved that the tumor antigen sensitizing and the gene silencing are effective methods for the preparation of the DC vaccines. The aim of this study is to investigate the specific anti-laryngocarcinoma immune response for the suppression of cytokine signaling1 (SOCS1) silencing and Hep-2 sensitizing DC. MATERIALS AND METHODS: The dendritic cells derived from peripheral blood mononuclear cells were induced by cytokines GM-CSF, IL-4, and TNF-α in vitro, and the morphological characteristics of dendritic cells were observed under a microscope, indicating that they successfully differentiated into dendritic cells. The RNA interference vector was used to transfect dendritic cells. The expression of SOCS1 was detected by Western blot and the effective target sequence for inhibiting the expression of SOCS1 was screened. The expressions of CD83, CD86, and HLA-DR on dendritic cells were detected by flow cytometry. The content of IFN-γ in the supernatant was analyzed by enzyme-linked immunosorbent assay (ELISA). Methyl thiazolyl tetrazolium (MTT) was used to evaluate the ability of dendritic cells to stimulate T cell proliferation and induce the killing activity of cytotoxic T cells. RESULTS: The result of PCR and Western blot analysis shows that the expression of SOCS1 significantly decreased under the influence of the 5th interference sequence. The flow cytometric analysis results show that SOCS1 silencing and Hep-2 sensitizing dendritic cells had high expressions of CD83 (85.61±0.96)%, CD86 (96.86±1.20)%, and HLA-DR (98.02±0.94)%. The DC vaccine could increase the production of IFN-γ according to the ELISA assay results. The MTT assay results show that the DC vaccine could also stimulate the proliferation of the T cells and effectively and eventually enhance the specific killing effect of CTL. CONCLUSIONS: SOCS1 silencing and Hep-2 sensitizing DC vaccine could induce an effective and specific anti-laryngocarcinoma immune response.

SOCS1 Is a Key Molecule That Prevents Regulatory T Cell Plasticity under Inflammatory Conditions.

We previously showed that regulatory T cells (Tregs) from T cell-specific Socs1-deficient mice (Socs1fl/flLck-Cre+ mice) easily convert into Th1- or Th17-like cells (ex-Tregs), which lose Foxp3 expression and suppressive functions in vivo. Because Tregs in Socs1fl/flLck-Cre+ mice are constantly exposed to a large amount of inflammatory cytokines produced by non-Tregs in vivo, in this study we analyzed Treg-specific Socs1-deficient mice (Socs1fl/flFoxp3YFP-Cre mice). These mice developed dermatitis, splenomegaly, and lymphadenopathy that were much milder than those in Socs1fl/flLck-Cre+ mice. A fate mapping study revealed that Socs1 deficiency accelerated the conversion of Tregs to Foxp3-IFN-γ+ ex-Tregs in the tumor microenvironment and suppressed tumor growth. When transferred into Rag2-/- mice, Tregs from Socs1fl/flLck-Cre+ mice easily lost Foxp3 expression, whereas those from Socs1fl/flFoxp3YFP-Cre mice maintained Foxp3 expression. Although Tregs from Socs1fl/flLck-Cre+ mice produced IFN-γ after a 3-d culture in response to anti-CD3/CD28 Ab stimulation in vitro, Tregs from Socs1fl/flFoxp3YFP-Cre mice did not. This finding suggested that the inflammatory conditions in Socs1fl/flLck-Cre+ mice modified the born nature of Socs1-deficient Tregs. To investigate this mechanism, Tregs from Socs1fl/flFoxp3YFP-Cre mice were cultured with APCs from Socs1fl/flLck-Cre+ mice. These APCs facilitated STAT4 phosphorylation, IFN-γ production, and loss of Foxp3 expression in Tregs from Socs1fl/flFoxp3YFP-Cre mice in an IL-12-dependent manner. The results indicate that Socs1-deficient Tregs tend to convert into ex-Tregs under the inflammatory conditions in which APCs are highly activated, and that SOCS1 could be a useful target for enhancement of anti-tumor immunity.

Suppressor of cytokine signaling 1-dependent regulation of the expression and oncogenic functions of p21(CIP1/WAF1) in the liver.

The SOCS1 gene coding for suppressor of cytokine signaling 1 is frequently repressed in hepatocellular carcinoma (HCC), and hence SOCS1 is considered a tumor suppressor in the liver. However, the tumor-suppressor mechanisms of SOCS1 are not yet well understood. SOCS1 is known to inhibit pro-inflammatory cytokine production and signaling and to promote activation of the p53 tumor suppressor. However, we observed that SOCS1-deficient mice developed numerous and large liver tumor nodules following treatment with the hepatocarcinogen diethylnitrosamine (DEN) without showing increased interleukin-6 production or activation of p53. On the other hand, the livers of DEN-treated Socs1-null mice showed elevated levels of p21(CIP1/WAF1) protein (p21). Even though p21 generally functions as a tumor suppressor, paradoxically many cancers, including HCC, are known to express elevated levels of p21 that correlate with poor prognosis. We observed elevated p21 expression also in the regenerating livers of SOCS1-deficient mice and in cisplatin-treated Socs1-null hepatocytes, wherein the p21 protein showed increased stability. We show that SOCS1 interacts with p21 and promotes its ubiquitination and proteasomal degradation. Besides, the DEN-treated livers of Socs1-null mice showed increased nuclear and cytosolic p21 staining, and the latter was associated with growth factor-induced, phosphatidylinositol 3-kinase-dependent phosphorylation of p21 in SOCS1-deficient hepatocytes. Cytosolic p21 is often associated with malignancy and chemo-resistance in many cancers. Accordingly, SOCS1-deficient hepatocytes showed increased resistance to apoptosis that was reversed by shRNA-mediated p21 knockdown. In the regenerating livers of Socs1-null mice, increased p21 expression coincided with elevated cyclinD levels. Correspondingly, SOCS1-deficient hepatocytes showed increased proliferation to growth factor stimulation that was reversed by p21 knockdown. Overall, our findings indicate that the tumor-suppressor functions of SOCS1 in the liver could be mediated, at least partly, via regulation of the expression, stability and subcellular distribution of p21 and its paradoxical oncogenic functions, namely, resistance to apoptosis and increased proliferation.