Impact of STAT6 Variants on the Response to Proton Pump Inhibitors and Comorbidities in Patients with Eosinophilic Esophagitis.

Proton pump inhibitors (PPIs) are the first-line drug for eosinophilic esophagitis (EoE), although it is estimated that there is a lack of histological remission in 50% of patients. This research aimed to identify pharmacogenetic biomarkers predictive of PPI effectiveness and to study their association with disease features. Peak eosinophil count (PEC) and the endoscopic reference score (EREFS) were determined before and after an eight-week PPI course in 28 EoE patients. The impact of the signal transducer and activator of transcription 6 (STAT6), CYP2C19, CYP3A4, CYP3A5, and ABCB1 genetic variations on baseline PEC and EREFS, their reduction and histological response, and on EoE symptoms and comorbidities was analyzed. PEC reduction was higher in omeprazole-treated patients (92.5%) compared to other PPIs (57.9%, p = 0.003). STAT6 rs12368672 (g.18453G>C) G/G genotype showed higher baseline PEC values compared to G/C and C/C genotypes (83.2 vs. 52.9, p = 0.027). EREFS reduction in STAT6 rs12368672 G/G and G/C genotypes was higher than in the C/C genotype (36.7% vs. -75.0% p = 0.011). However, significance was lost after Bonferroni correction. Heartburn incidence was higher in STAT6 rs167769 (g.27148G>A) G/G patients compared to G/A (54.55% vs. 11.77%, p = 0.030). STAT6 rs12368672G>C and rs167769G>A variants might have a relevant impact on EoE status and PPI response. Further research is warranted to clarify the clinical relevance of these variants.

Wogonoside Ameliorates Airway Inflammation and Mucus Hypersecretion via NF-κB/STAT6 Signaling in Ovalbumin-Induced Murine Acute Asthma.

Asthma is recognized as a chronic respiratory illness characterized by airway inflammation and airway hyperresponsiveness. Wogonoside, a flavonoid glycoside, is reported to significantly alleviate the inflammation response and oxidative stress. Herein, this study aimed to investigate the therapeutic effect and underlying mechanism of wogonoside on airway inflammation and mucus hypersecretion in a murine asthma model and in human bronchial epithelial cells (16HBE). BALB/c mice were sensitized and challenged with ovalbumin (OVA). Pulmonary function and the number of cells in the bronchoalveolar lavage fluid (BALF) were examined. Pathological changes in lung tissue in each group were evaluated via hematoxylin and eosin and periodic acid-Schiff staining, and changes in levels of cytokines in BALF and of immunoglobulin E in serum were determined via an enzyme-linked immunosorbent assay. The expression of relevant genes in lung tissue was analyzed via real-time PCR. Western blotting and immunofluorescence were employed to detect the expression of relevant proteins in lung tissue and 16HBE cells. Treatment with 10 and 20 mg/kg wogonoside significantly attenuated the OVA-induced increase of inflammatory cell infiltration, mucus secretion, and goblet cell percentage and improved pulmonary function. Wogonoside treatment reduced the level of T-helper 2 cytokines including interleukin (IL)-4, IL-5, and IL-13 in BALF and of IgE in serum and decreased the mRNA levels of cytokines (IL-4, IL-5, IL-6, IL-13, and IL-1ß and tumor necrosis factor-α), chemokines (CCL-2, CCL-11, and CCL-24), and mucoproteins (MUC5AC, MUC5B, and GOB5) in lung tissues. The expression of MUC5AC and the phosphorylation of STAT6 and NF-κB p65 in lung tissues and 16HBE cells were significantly downregulated after wogonoside treatment. Thus, wogonoside treatment may effectively decrease airway inflammation, airway remodeling, and mucus hypersecretion via blocking NF-κB/STAT6 activation.

Exosome circATP8A1 induces macrophage M2 polarization by regulating the miR-1-3p/STAT6 axis to promote gastric cancer progression.

Circular RNAs (circRNAs) play important roles in gastric cancer progression but the regulatory role of circRNAs in controlling macrophage function remains elusive. Exosomes serve as cargo for circRNAs and play a crucial role as mediators in facilitating communication between cancer cells and the tumor microenvironment. In this study, we found that circATP8A1, a previously unreported circular RNA, is highly expressed in both gastric cancer tissues and exosomes derived from plasma. Increased circATP8A1 was associated with advanced TNM stage and worse prognosis in patients with gastric cancer. We showed that  the circATP8A1 knockdown significantly inhibited gastric cancer proliferation and invasion in vitro and in vivo. Functionally, exosome circATP8A1 induced the M2 polarization of macrophages through the STAT6 pathway instead of the STAT3 pathway. Mechanistically, circATP8A1 was shown to activate the STAT6 pathway through competitive binding to miR-1-3p, as confirmed by Fluorescence In Situ Hybridization (FISH), RNA immunoprecipitation, RNA pulldown, and Luciferase reporter assays. The reversal of circATP8A1-induced STAT6 pathway activation and macrophage polarization was observed upon blocking miR-1-3p. Macrophages treated with exosomes from gastric cancer cells overexpressing circATP8A1 were able to promote gastric cancer migration, while knockdown of circATP8A1 reversed these effects in vivo. In summary, exosome-derived circATP8A1 from gastric cancer cells induce macrophages M2 polarization via the circATP8A1/miR-1-3p/STAT6 axis, and tumor progression. Our results highlight circATP8A1 as a potential prognostic biomarker and therapeutic target in gastric cancer.

EGFR overexpression and macrophage infiltration correlate with poorer prognosis in HPV-negative oropharyngeal cancer via STAT6 signaling.

BACKGROUND: The prevalence of HPV-negative oropharyngeal cancer (OPC) is higher in Asian countries. Patients with HPV-negative OPC suffer poor outcomes. Multi-omics analysis could provide researchers and clinicians with more treatment targets for this high-risk group. We aimed to explore the prognostic significance of EGFR overexpression and macrophage infiltration in OPC, especially HPV-negative OPC in this study. METHODS: EGFR alternation was evaluated with TCGA, PanCancer Atlas through cBioProtal. EGFR mRNA expression in HPV-negative head and neck squamous cell carcinoma was analyzed using the Tumor Immune Estimation Resource (TIMER 2.0). We also examined EGFR/STAT6/MRC1 expression in paraffin-embedded tissues from a p16-negative OPC cohort. The correlation between EGFR expression and macrophage activation was explored using Person's correlation coefficient. The impact of biomarkers or macrophage infiltration on 5-year overall survival and recurrence-free survival were analyzed using Kaplan-Meier survival curves. RESULTS: EGFR alteration rate was 15%, 13%, and 0% for HPV-negative HNSCC (excluding OPC), HPV-negative OPC, and HPV-positive OPC. High EGFR expression was associated with increased tumor infiltration of immune cells, such as macrophages. We observed positive correlations between EGFR, STAT6, and MRC1 expression in p16-negative OPC. Higher MRC1 expression was associated with poorer survival rates. CONCLUSIONS: There is strong correlation between EGFR overexpression and M2 polarization in patients with p16-negative OPC. Immunotherapy with or without EGFR inhibitor could be considered in these high-risk patients.

Transcriptomic and metabolomic analysis unveils nanoplastic-induced gut barrier dysfunction via STAT1/6 and ERK pathways.

The widespread prevalence of micro and nanoplastics in the environment raises concerns about their potential impact on human health. Recent evidence demonstrates the presence of nanoplastics in human blood and tissues following ingestion and inhalation, yet the specific risks and mechanisms of nanoplastic toxicity remain inadequately understood. In this study, we aimed to explore the molecular mechanisms underlying the toxicity of nanoplastics at both systemic and molecular levels by analyzing the transcriptomic/metabolomic responses and signaling pathways in the intestines of mice after oral administration of nanoplastics. Transcriptome analysis in nanoplastic-administered mice revealed a notable upregulation of genes involved in pro-inflammatory immune responses. In addition, nanoplastics substantially reduced the expression of tight junction proteins, including occludin, zonula occluden-1, and tricellulin, which are crucial for maintaining gut barrier integrity and function. Importantly, nanoplastic administration increased gut permeability and exacerbated dextran sulfate sodium-induced colitis. Further investigation into the underlying molecular mechanisms highlighted significant activation of signaling transsducer and activator of transcription (STAT)1 and STAT6 by nanoplastic administration, which was in line with the elevation of interferon and JAK-STAT pathway signatures identified through transcriptome enrichment analysis. Additionally, the consumption of nanoplastics specifically induced nuclear factor kappa-B (NF-κB) and extracellular signal-regulated kinase (ERK)1/2 signaling pathways in the intestines. Collectively, this study identifies molecular mechanisms contributing to adverse effects mediated by nanoplastics in the intestine, providing novel insights into the pathophysiological consequences of nanoplastic exposure.

Solitary fibrous tumor: Can the new Huang risk stratification system for orbital tumors improve prognostic accuracy in other tumor locations?

Solitary fibrous tumors (SFTs) are known for their heterogeneous morphology, characterized by a variety of cell shapes and different growth patterns. They can also arise in various anatomical locations, most commonly in extremities and deep soft tissues. Despite this diversity in morphology and location, all SFTs share a common molecular signature involving the NAB2::STAT6 gene fusion. Due to their unpredictable clinical behavior, establishing prognostic factors is crucial. This study aims to evaluate an orbital risk stratification system (RSS) proposed by Huang et al. for use in extraorbital SFTs using a database of 97 cases. The Huang model takes into consideration tumor size, mitotic figures, Ki-67 index, and dominant constituent cell (DCC) as key variables. Survival analysis confirmed the model's predictive value, with higher-risk scores being associated with poorer outcomes. However, in contrast to the orbital SFTs studied by Huang et al., our study did not find a correlation between tumor size and recurrence in extraorbital cases. While the Huang model performs slightly better than other RSS, it falls short on achieving statistical significance in distinguishing recurrence risk groups in extraorbital locations. In conclusion, this study validates the Huang RSS for use in extraorbital SFTs and underscores the importance of considering DCC, mitotic count, and Ki-67 together. However, we found that including tumor size in this model did not improve prognostic significance in extraorbital SFTs. Despite the benefits of this additional RSS, vigilant monitoring remains essential, even in cases classified as low-risk due to the inherent unpredictability of SFT clinical outcomes.

Human germline gain-of-function in STAT6: from severe allergic disease to lymphoma and beyond.

Signal transducer and activator of transcription (STAT)-6 is a transcription factor central to pro-allergic immune responses, although the function of human STAT6 at the whole-organism level has long remained unknown. Germline heterozygous gain-of-function (GOF) rare variants in STAT6 have been recently recognized to cause a broad and severe clinical phenotype of early-onset, multi-system allergic disease. Here, we provide an overview of the clinical presentation of STAT6-GOF disease, discussing how dysregulation of the STAT6 pathway causes severe allergic disease, and identifying possible targeted treatment approaches. Finally, we explore the mechanistic overlap between STAT6-GOF disease and other monogenic atopic disorders, and how this group of inborn errors of immunity (IEIs) powerfully inform our fundamental understanding of common human allergic disease.

STAT6 mutations enriched at diffuse large B-cell lymphoma relapse reshape the tumor microenvironment.

Diffuse large B-cell lymphoma (DLBCL) relapses in approximately 40% of patients following frontline therapy. We reported that STAT6D419 mutations are enriched in relapsed/refractory DLBCL (rrDLBCL) samples, suggesting that JAK/STAT signaling plays a role in therapeutic resistance. We hypothesized that STAT6D419 mutations can improve DLBCL cell survival by reprogramming the microenvironment to sustain STAT6 activation. Thus, we investigated the role of STAT6D419 mutations on DLBCL cell growth and its microenvironment. We found that phospho-STAT6D419N was retained in the nucleus longer than phospho-STAT6WT following IL-4 stimulation, and STAT6D419N recognized a more restricted DNA-consensus sequence than STAT6WT. Upon IL-4 induction, STAT6D419N expression led to a higher magnitude of gene expression changes, but in a more selective list of gene targets compared with STATWT. The most significantly expressed genes induced by STAT6D419N were those implicated in survival, proliferation, migration, and chemotaxis, in particular CCL17. This chemokine, also known as TARC, attracts helper T-cells to the tumor microenvironment, especially in Hodgkin's lymphoma. To this end, in DLBCL, phospho-STAT6+ rrDLBCL cells had a greater proportion of infiltrating CD4+ T-cells than phospho-STAT6- tumors. Our findings suggest that STAT6D419 mutations in DLBCL lead to cell autonomous changes, enhanced signaling, and altered composition of the tumor microenvironment.

STAT3 and STAT6 polymorphisms predict the severity of adverse reactions in Chinese NSCLC patients receiving EGFR-TKIs therapy.

A total of 162 non-small cell lung cancer (NSCLC) patients were divided into discovery (N = 68) and validation (N = 94) groups. Nine Janus kinase/Signal transducer and activator of transcription (JAK/STAT) pathway-related single nucleotide polymorphisms were selected to explore the potential associations between genetic polymorphisms and adverse drug reactions (ADRs). The TT genotype of STAT6 rs324011 was significantly associated with severe ADRs in the recessive genetic model (TT vs. CC + CT, OR = 13.5, 95% CI = 2.12-86.09, p = 0.006 in the discovery group; OR = 8.41, 95% CI = 1.95-36.19, p = 0.004 in the validation group). The T allele was associated with a higher incidence of severe ADRs than was the C allele of rs324011 (OR = 3.67, 95% CI = 1.46-9.19, p = 0.006 in the discovery group; OR = 3.17, 95% CI = 1.44-6.99, p = 0.004 in the validation group). Patients with the CC genotype in STAT3 rs1053023 (and rs1053005) or the TT genotype of STAT6 rs324011 were likely to experience severe epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) related ADRs.

Chitosan-coated artesunate protects against ulcerative colitis via STAT6-mediated macrophage M2 polarization and intestinal barrier protection.

Oral delivery of chitosan-coated artesunate (CPA) has been proven to be effective at preventing ulcerative colitis (UC) in mice. However, the anti-inflammatory mechanism is not fully understood. STAT6 is a key transcription factor that promotes anti-inflammatory effects by inducing M2 and Th2 dominant phenotypes, therefore we hypothesized STAT6 might play a key role in the process. To prove it, a STAT6 gene knockout macrophage cell line (STAT6-/- RAW264.7, by CRISPR/Cas9 method), and its corresponding Caco-2/RAW264.7 co-culture system combined with the STAT6 inhibitor (AS1517499, AS) in a mouse UC model were established and studied. The results showed that CPA remarkably suppressed the activation of TLR-4/NF-κB pathway and the mRNA levels of proinflammatory cytokines, while increased the IL-10 levels in RAW264.7. This effect of CPA contributed to the protection of the ZO-1 in Caco-2 which was disrupted upon the stimulation to macrophages. Simultaneously, CPA reduced the expression of CD86 but increase the expression of CD206 and p-STAT6 in LPS-stimulated RAW264.7 cells. However, above alterations were not obvious as in STAT6-/- RAW264.7 and its co-culture system, suggesting STAT6 plays a key role. Furthermore, CPA treatment significantly inhibited TLR-4/NF-κB activation, intestinal macrophage M1 polarization and mucosal barrier injury induced by DSS while promoted STAT6 phosphorylation in the UC mouse model, but this effect was also prominently counteracted by AS. Therefore, our data indicate that STAT6 is a major regulator in the balance of M1/M2 polarization, intestinal barrier integrity and then anti-colitis effects of CPA. These findings broaden our understanding of how CPA fights against UC and imply an alternative treatment strategy for UC via this pathway.

STAT6-induced production of mucus and resistin-like molecules in lung Club cells does not protect against helminth or influenza A virus infection.

Airway epithelial cells contribute to a variety of lung diseases including allergic asthma, where IL-4 and IL-13 promote activation of the transcription factor STAT6. This leads to goblet cell hyperplasia and the secretion of effector molecules by epithelial cells. However, the specific effect of activated STAT6 in lung epithelial cells is only partially understood. Here, we created a mouse strain to selectively investigate the role of constitutively active STAT6 in Club cells, a subpopulation of airway epithelial cells. CCSP-Cre_STAT6vt mice and bronchiolar organoids derived from these show an enhanced expression of the chitinase-like protein Chil4 (Ym2) and resistin-like molecules (Relm-α, -ß, -γ). In addition, goblet cells of these mice spontaneously secrete mucus into the bronchi. However, the activated epithelium resulted neither in impaired lung function nor conferred a protective effect against the migrating helminth Nippostrongylus brasiliensis. Moreover, CCSP-Cre_STAT6vt mice showed similar allergic airway inflammation induced by live conidia of the fungus Aspergillus fumigatus and similar recovery after influenza A virus infection compared to control mice. Together these results highlight that STAT6 signaling in Club cells induces the secretion of Relm proteins and mucus without impairing lung function, but this is not sufficient to confer protection against helminth or viral infections.

Hookworms dynamically respond to loss of Type 2 immune pressure.

The impact of the host immune environment on parasite transcription and fitness is currently unknown. It is widely held that hookworm infections have an immunomodulatory impact on the host, but whether the converse is true remains unclear. Immunity against adult-stage hookworms is largely mediated by Type 2 immune responses driven by the transcription factor Signal Transducer and Activator of Transcription 6 (STAT6). This study investigated whether serial passage of the rodent hookworm Nippostrongylus brasiliensis in STAT6-deficient mice (STAT6 KO) caused changes in parasites over time. After adaptation to STAT6 KO hosts, N. brasiliensis increased their reproductive output, feeding capacity, energy content, and body size. Using an improved N. brasiliensis genome, we found that these physiological changes corresponded with a dramatic shift in the transcriptional landscape, including increased expression of gene pathways associated with egg production, but a decrease in genes encoding neuropeptides, proteases, SCP/TAPS proteins, and transthyretin-like proteins; the latter three categories have been repeatedly observed in hookworm excreted/secreted proteins (ESPs) implicated in immunosuppression. Although transcriptional changes started to appear in the first generation of passage in STAT6 KO hosts for both immature and mature adult stages, downregulation of the genes putatively involved in immunosuppression was only observed after multiple generations in this immunodeficient environment. When STAT6 KO-adapted N. brasiliensis were reintroduced to a naive WT host after up to 26 generations, this progressive change in host-adaptation corresponded to increased production of inflammatory cytokines by the WT host. Surprisingly, however, this single exposure of STAT6 KO-adapted N. brasiliensis to WT hosts resulted in worms that were morphologically and transcriptionally indistinguishable from WT-adapted parasites. This work uncovers remarkable plasticity in the ability of hookworms to adapt to their hosts, which may present a general feature of parasitic nematodes.

STAT6 promoting oxalate crystal deposition-induced renal fibrosis by mediating macrophage-to-myofibroblast transition via inhibiting fatty acid oxidation.

OBJECTIVE AND DESIGN: Kidney stones commonly occur with a 50% recurrence rate within 5 years, and can elevate the risk of chronic kidney disease. Macrophage-to-myofibroblast transition (MMT) is a newly discovered mechanism that leads to progressive fibrosis in different forms of kidney disease. In this study, we aimed to investigate the role of MMT in renal fibrosis in glyoxylate-induced kidney stone mice and the mechanism by which signal transducer and activator of transcription 6 (STAT6) regulates MMT. METHODS: We collected non-functioning kidneys from patients with stones, established glyoxylate-induced calcium oxalate stone mice model and treated AS1517499 every other day in the treatment group, and constructed a STAT6-knockout RAW264.7 cell line. We first screened the enrichment pathway of the model by transcriptome sequencing; detected renal injury and fibrosis by hematoxylin eosin staining, Von Kossa staining and Sirius red staining; detected MMT levels by multiplexed immunofluorescence and flow cytometry; and verified the binding site of STAT6 at the PPARα promoter by chromatin immunoprecipitation. Fatty acid oxidation (FAO) and fibrosis-related genes were detected by western blot and real-time quantitative polymerase chain reaction. RESULTS: In this study, we found that FAO was downregulated, macrophages converted to myofibroblasts, and STAT6 expression was elevated in stone patients and glyoxylate-induced kidney stone mice. The promotion of FAO in macrophages attenuated MMT and upregulated fibrosis-related genes induced by calcium oxalate treatment. Further, inhibition of peroxisome proliferator-activated receptor-α (PPARα) eliminated the effect of STAT6 deletion on FAO and fibrosis-associated protein expression. Pharmacological inhibition of STAT6 also prevented the development of renal injury, lipid accumulation, MMT, and renal fibrosis. Mechanistically, STAT6 transcriptionally represses PPARα and FAO through cis-inducible elements located in the promoter region of the gene, thereby promoting MMT and renal fibrosis. CONCLUSIONS: These findings establish a role for STAT6 in kidney stone injury-induced renal fibrosis, and suggest that STAT6 may be a therapeutic target for progressive renal fibrosis in patients with nephrolithiasis.

Solitary Fibrous Tumor in the Retroperitoneal Space Arising from the Diaphragm.

BACKGROUND/AIM: We present a case of solitary fibrous tumor, arising from the diaphragm in the retroperitoneal space, that was resected with robotic assistance. CASE REPORT: An 85-year-old female patient was referred to our hospital for evaluation of a suspected right renal tumor. Abdominal contrast-enhanced computed tomography revealed a tumor (maximum diameter, 36 mm) protruding from the superior pole of the right kidney. The patient was scheduled for robot-assisted, retroperitoneoscopic, partial nephrectomy based on a preoperative diagnosis of renal cell carcinoma. Intraoperative findings revealed that the tumor originated from the diaphragm and had no continuity with the renal parenchyma. Pathological examination revealed a solitary fibrous tumor. CONCLUSION: Solitary fibrous tumors are rare soft-tissue neoplasms with a distinct molecular feature of the fusion of nerve growth factor-inducible A gene-binding protein 2 with signal transducer and activator of transcription 6 gene (NAB2::STAT6). We believe that this is the first reported case of a solitary fibrous tumor arising from the diaphragm in the retroperitoneal space.

Interleukin-4 Promotes Human Metapneumovirus Replication Through the JAK/STAT6 Pathway.

Respiratory virus infections are the main causes of pediatric diseases. Human metapneumovirus (hMPV) is an enveloped RNA virus similar to severe acute respiratory syndrome coronavirus type 2, both of which have emerged as important new respiratory viruses. Recent studies have found that interleukin-4 (IL-4) is involved in the replication of a variety of viruses, and its role differs in different viruses. The purpose of this study was to investigate the effect of IL-4 on hMPV and to elucidate its mechanism of action. We found that hMPV infection promoted the expression of IL-4 in human bronchial epithelial cells. The replication of the virus was reduced using small interfering RNA knockdown of IL-4 expression, while the addition of exogenous recombinant human IL-4 to IL-4 knockdown cells restored viral replication ability. These results demonstrate that the expression of IL-4 is closely related to the replication of hMPV; moreover, further experiments revealed that IL-4 promotes the replication of hMPV through a mechanism dependent on the Janus kinase/signal transductor and transcription activator 6 signaling pathway. Therefore, anti-IL-4 strategies may be a promising avenue for the treatment of hMPV infection, representing an important breakthrough for children at risk from hMPV infection.

LILRB4 regulates the function of decidual MDSCs via the SHP-2/STAT6 pathway during Toxoplasma gondii infection.

BACKGROUND: Toxoplasma gondii infection can cause adverse pregnancy outcomes, such as recurrent abortion, fetal growth restriction and infants with malformations, among others. Decidual myeloid-derived suppressor cells (dMDSCs) are a novel immunosuppressive cell type at the fetal-maternal interface which play an important role in sustaining normal pregnancy that is related to their high expression of the inhibitory molecule leukocyte immunoglobulin-like receptor B4 (LILRB4). It has been reported that the expression of LILRB4 is downregulated on decidual macrophages after T. gondii infection, but it remains unknown whether T. gondii infection can induce dMDSC dysfunction resulting from the change in LILRB4 expression. METHODS: LILRB4-deficient (LILRB4-/-) pregnant mice infected with T. gondii with associated adverse pregnancy outcomes, and anti-LILRB4 neutralized antibodies-treated infected human dMDSCs were used in vivo and in vitro experiments, respectively. The aim was to investigate the effect of LILRB4 expression on dMDSC dysfunction induced by T. gondii infection. RESULTS: Toxoplasma gondii infection was observed to reduce STAT3 phosphorylation, resulting in decreased LILRB4 expression on dMDSCs. The levels of the main functional molecules (arginase-1 [Arg-1], interleukin-10 [IL-10]) and main signaling molecules (phosphorylated Src-homology 2 domain-containing protein tyrosine phosphatase [p-SHP2], phosphorylated signal transducer and activator of transcription 6 [p-STAT6]) in dMDSCs were all significantly reduced in human and mouse dMDSCs due to the decrease of LILRB4 expression induced by T. gondii infection. SHP-2 was found to directly bind to STAT6 and STAT6 to bind to the promoter of the Arg-1 and IL-10 genes during T. gondii infection. CONCLUSIONS: The downregulation of LILRB4 expression on dMDSCs induced by T. gondii infection could regulate the expression of Arg-1 and IL-10 via the SHP-2/STAT6 pathway, resulting in the dysfunction of dMDSCs, which might contribute to adverse outcomes during pregnancy by T. gondii infection.

Autosomal Dominant STAT6 Gain of Function Causes Severe Atopy Associated with Lymphoma.

The transcription factor STAT6 (Signal Transducer and Activator of Transcription 6) is a key regulator of Th2 (T-helper 2) mediated allergic inflammation via the IL-4 (interleukin-4) JAK (Janus kinase)/STAT signalling pathway. We identified a novel heterozygous germline mutation STAT6 c.1255G > C, p.D419H leading to overactivity of IL-4 JAK/STAT signalling pathway, in a kindred affected by early-onset atopic dermatitis, food allergy, eosinophilic asthma, anaphylaxis and follicular lymphoma. STAT6 D419H expression and functional activity were compared with wild type STAT6 in transduced HEK293T cells and to healthy control primary skin fibroblasts and peripheral blood mononuclear cells (PBMC). We observed consistently higher STAT6 levels at baseline and higher STAT6 and phosphorylated STAT6 following IL-4 stimulation in D419H cell lines and primary cells compared to wild type controls. The pSTAT6/STAT6 ratios were unchanged between D419H and control cells suggesting that elevated pSTAT6 levels resulted from higher total basal STAT6 expression. The selective JAK1/JAK2 inhibitor ruxolitinib reduced pSTAT6 levels in D419H HEK293T cells and patient PBMC. Nuclear staining demonstrated increased STAT6 in patient fibroblasts at baseline and both STAT6 and pSTAT6 after IL-4 stimulation. We also observed higher transcriptional upregulation of downstream genes (XBP1 and EPAS1) in patient PBMC. Our study confirms STAT6 gain of function (GOF) as a novel monogenetic cause of early onset atopic disease. The clinical association of lymphoma in our kindred, along with previous data linking somatic STAT6 D419H mutations to follicular lymphoma suggest that patients with STAT6 GOF disease may be at higher risk of lymphomagenesis.245 words.