Impact of STAT-signaling pathway on cancer-associated fibroblasts in colorectal cancer and its role in immunosuppression.

Colorectal cancer (CRC) remains one of the most commonly diagnosed and deadliest types of cancer worldwide. CRC displays a desmoplastic reaction (DR) that has been inversely associated with poor prognosis; less DR is associated with a better prognosis. This reaction generates excessive connective tissue, in which cancer-associated fibroblasts (CAFs) are critical cells that form a part of the tumor microenvironment. CAFs are directly involved in tumorigenesis through different mechanisms. However, their role in immunosuppression in CRC is not well understood, and the precise role of signal transducers and activators of transcription (STATs) in mediating CAF activity in CRC remains unclear. Among the myriad chemical and biological factors that affect CAFs, different cytokines mediate their function by activating STAT signaling pathways. Thus, the harmful effects of CAFs in favoring tumor growth and invasion may be modulated using STAT inhibitors. Here, we analyze the impact of different STATs on CAF activity and their immunoregulatory role.

STAT3 gain-of-function mutation in an adult patient.

Germline gain-of-function (GOF) mutation of the signal transducer and activator of transcription 3 (STAT3) gene causes a disease clinically characterized by a significant lymphoproliferation, including lymphadenopathy and/or hepatosplenomegaly, as well as childhood onset autoimmunity. Here we present an adult patient who, during his early years of life, presented recurrent infections, autoimmune hemolytic anemia and benign lymphoproliferative disease, characterized by hepatosplenomegaly and lymphadenopathy, being diagnosed with common variable immunodeficiency (CVID) at 13 years of age. He was diagnosed with lymphocytic interstitial pneumonia at the age of 20. When he was 40 years old, after a diagnostic review, it was decided to perform genetic studies. A heterozygous mutation in STAT3 NM_003150 c.2141C>T, p.P714L was detected by whole exome sequencing and validated by Sanger. Previously published functional studies performed in two siblings showed that this mutation resulted in gain-of-function. They were initially diagnosed with autoimmune lymphoproliferative syndrome, and later with STAT3 GOF as a second genetic defect. Our patient developed severe pulmonary disease and died, without access to treatment targeted to his molecular defect due to the advanced nature of his pulmonary involvement and the fact that many of the therapies were still in development at that time. The diagnosis of STAT3 GOF mutations should be suspected in patients with early-onset of lymphoproliferative disease, autoimmunity and hypogammaglobulinemia. This must be considered especially in the group of CVID patients with these characteristics, in order to allow the implementation of treatments targeting the molecular defect (JAK inhibitors and Il-6 receptor antagonists) that could modify the disease evolution.

Mutaciones en línea germinal con ganancia de función (GOF) del gen transductor de señales y activador de la transcripción 3 (STAT3) provocan una enfermedad caracterizada por importante linfoproliferación, incluyendo linfadenopatías y/o hepatoesplenomegalia, así como autoinmunidad de inicio en la infancia. Presentamos un paciente adulto que, durante sus primeros años de vida, presentó infecciones recurrentes, anemia hemolítica autoinmune y enfermedad linfoproliferativa benigna, caracterizada inicialmente por hepatoesplenomegalia y linfoadenopatías, diagnosticado de inmunodeficiencia común variable (IDCV) a los 13 años. A los 20 años, al ser estudiado por compromiso pulmonar, se diagnosticó neumonía intersticial linfocítica. A los 40 años, tras revisión diagnóstica se decidió realizar estudios genéticos. Por secuenciación del exoma completo se detectó una mutación heterocigota en STAT3 NM_003150 c.2141C>T, p.P714L, que se validó por Sanger. Estudios funcionales previamente publicados realizados en dos hermanos con diagnóstico inicial de síndrome linfoproliferativo autoinmune, mostraron que esta mutación daba lugar a una ganancia de función. Nuestro paciente desarrolló enfermedad pulmonar grave y falleció a los 41 años, sin posibilidad de acceder a tratamiento dirigido a su defecto molecular por lo avanzado de su compromiso pulmonar y a que muchas de las terapias se encontraban en ese momento en desarrollo. El diagnóstico de mutaciones STAT3 GOF debe sospecharse en pacientes con enfermedad linfoproliferativa temprana, autoinmunidad e hipogammaglobulinemia. Esto debe ser considerado especialmente en pacientes con IDCV con estas carac terísticas, para permitir la implementación de tratamientos dirigidos al defecto molecular (inhibidores de JAK y antagonistas del receptor de Il-6) que podrían modificar la evolución de la enfermedad.

Diosmetin inhibits cell proliferation and promotes apoptosis through STAT3/c-Myc signaling pathway in human osteosarcoma cells.

BACKGROUND: Diosmetin is a bioflavonoid compound naturally abundant in citrus fruits. It is found to perform a variety of activities, while its antitumor property in osteosarcoma, a malignant tumor with unmet clinical treatment, remained unknown. METHODS: Colony formation assay, cell cycle analysis and apoptosis analysis were conducted respectively to observe the effect of diosmetin on cell proliferation and apoptosis in human osteosarcoma cells. Western blot and immunoprecipitation were used to detect the expression of apoptotic molecules and activation of STAT3/c-Myc pathway in Saos-2 and U2SO cells. RESULTS: Diosmetin significantly inhibited cell proliferation, induced cell cycle arrest at G2/M phase and promoted cell apoptosis in both Saos-2 and U2SO cells. Moreover, Diosmetin downregulated the expression of anti-apoptotic protein Bcl-xL while upregulated the levels of pro-apoptotic proteins including cleaved Caspase-3, cleaved-PARP and Bax. Furthermore, diosmetin dose-dependently inhibited STAT3 phosphorylation, reduced the expression of its downstream protein c-Myc and impeded the interaction between STAT3 molecules. CONCLUSIONS: These results suggest that diosmetin exerts anti-osteosarcoma effects by suppressing cell proliferation and inducing apoptosis via inhibiting the activation of STAT3/c-Myc signaling pathway, which provide the possibility for diosmetin to be a chemotherapeutic candidate for osteosarcoma.

STAT3 gain-of-function mutation in an adult patient / Paciente adulto portador de una mutación con ganancia de función en el gen STAT3

Abstract Germline gain-of-function (GOF) mutation of the signal transducer and activator of transcription 3 (STAT3) gene causes a disease clinically characterized by a significant lymphoproliferation, includ ing lymphadenopathy and/or hepatosplenomegaly, as well as childhood onset autoimmunity. Here we present an adult patient who, during his early years of life, presented recurrent infections, autoimmune hemolytic anemia and benign lymphoproliferative disease, characterized by hepatosplenomegaly and lymphadenopathy, being diagnosed with common variable immunodeficiency (CVID) at 13 years of age. He was diagnosed with lymphocytic interstitial pneumonia at the age of 20. When he was 40 years old, after a diagnostic review, it was decided to perform genetic studies. A heterozygous mutation in STAT3 NM_003150 c.2141C>T, p.P714L was detected by whole exome sequencing and validated by Sanger. Previously published functional studies performed in two siblings showed that this mutation resulted in gain-of-function. They were initially diagnosed with autoimmune lymphoproliferative syndrome, and later with STAT3 GOF as a second genetic defect. Our patient developed severe pulmonary disease and died, without access to treatment targeted to his molecular defect due to the advanced nature of his pulmonary involvement and the fact that many of the therapies were still in develop ment at that time. The diagnosis of STAT3 GOF mutations should be suspected in patients with early-onset of lymphoproliferative disease, autoimmunity and hypogammaglobulinemia. This must be considered especially in the group of CVID patients with these characteristics, in order to allow the implementation of treatments target ing the molecular defect (JAK inhibitors and Il-6 receptor antagonists) that could modify the disease evolution.

Resumen Mutaciones en línea germinal con ganancia de función (GOF) del gen transductor de señales y acti vador de la transcripción 3 (STAT3) provocan una enfermedad caracterizada por importante linfoproliferación, incluyendo linfadenopatías y/o hepatoesplenomegalia, así como autoinmunidad de inicio en la infancia. Presen tamos un paciente adulto que, durante sus primeros años de vida, presentó infecciones recurrentes, anemia hemolítica autoinmune y enfermedad linfoproliferativa benigna, caracterizada inicialmente por hepatoespleno megalia y linfoadenopatías, diagnosticado de inmunodeficiencia común variable (IDCV) a los 13 años. A los 20 años, al ser estudiado por compromiso pulmonar, se diagnosticó neumonía intersticial linfocítica. A los 40 años, tras revisión diagnóstica se decidió realizar estudios genéticos. Por secuenciación del exoma completo se detectó una mutación heterocigota en STAT3 NM_003150 c.2141C>T, p.P714L, que se validó por Sanger. Estudios funcionales previamente publicados realizados en dos hermanos con diagnóstico inicial de síndrome linfoproliferativo autoinmune, mostraron que esta mutación daba lugar a una ganancia de función. Nuestro pa ciente desarrolló enfermedad pulmonar grave y falleció a los 41 años, sin posibilidad de acceder a tratamiento dirigido a su defecto molecular por lo avanzado de su compromiso pulmonar y a que muchas de las terapias se encontraban en ese momento en desarrollo. El diagnóstico de mutaciones STAT3 GOF debe sospecharse en pacientes con enfermedad linfoproliferativa temprana, autoinmunidad e hipogammaglobulinemia. Esto debe ser considerado especialmente en pacientes con IDCV con estas características, para permitir la implementación de tratamientos dirigidos al defecto molecular (inhibidores de JAK y antagonistas del receptor de Il-6) que podrían modificar la evolución de la enfermedad.

Ruxolitinib for Severe COVID-19-Related Hyperinflammation in Nonresponders to Steroids.

INTRODUCTION: Currently, severe acute respiratory syndrome coronavirus (SARS-CoV-2) infection is a major public health problem worldwide. Although most patients present a mild infection, effective strategies are required for patients who develop the severe disease. Anti-inflammatory treatment with JAK inhibitors has been considered in SARS-CoV-2. METHODS: In this study, we presented our experience in a group of severe SARS-CoV-2 Chilean patients. This prospective study was performed on consecutive patients presenting severe respiratory failure owing to COVID-19 or high-risk clinical condition associated with SARS-CoV-2, and who were treated with ruxolitinib for management of associated inflammation. Overall, 18 patients presenting SARS-CoV-2 viral-induced hyperinflammation were treated with ruxolitinib, with 16 patients previously treated with steroids, 4 with tocilizumab, and 3 with both treatments. RESULTS: Ten patients evolved with favorable response, including 7 patients admitted with severe respiratory failure (PaFi less than 200 mm Hg in high-flow nasal cannula), presenting complete regression of hyperinflammation, regression of the lung lesions, and subsequent discharge. In the remaining 8 patients, 25% showed reduced inflammation, but early discharge was not achieved owing to the slow evolution of respiratory failure. Unfortunately, 3 patients demonstrated a severe respiratory failure. The early initiation of ruxolitinib was found to be associated with better clinical evolution (p < 0.005). CONCLUSION: In this study, ruxolitinib resolved hyperinflammatory state in 55% of the patients, regardless of the previous steroid or tocilizumab therapy. Unfortunately, few patients demonstrated severe evolution despite ruxolitinib therapy. Notably, the treatment starting time appears to play an important role in achieving good outcomes. Further validation in randomized controlled trials is crucial.

Diosmetin inhibits cell proliferation and promotes apoptosis through STAT3/c-Myc signaling pathway in human osteosarcoma cells

BACKGROUND: Diosmetin is a bioflavonoid compound naturally abundant in citrus fruits. It is found to perform a variety of activities, while its antitumor property in osteosarcoma, a malignant tumor with unmet clinical treatment, remained unknown. METHODS: Colony formation assay, cell cycle analysis and apoptosis analysis were conducted respectively to observe the effect of diosmetin on cell proliferation and apoptosis in human osteosarcoma cells. Western blot and immunoprecipitation were used to detect the expression of apoptotic molecules and activation of STAT3/c-Myc pathway in Saos-2 and U2SO cells. RESULTS: Diosmetin significantly inhibited cell proliferation, induced cell cycle arrest at G2/M phase and promoted cell apoptosis in both Saos-2 and U2SO cells. Moreover, Diosmetin downregulated the expression of anti-apoptotic protein Bcl-xL while upregulated the levels of pro-apoptotic proteins including cleaved Caspase-3, cleaved-PARP and Bax. Furthermore, diosmetin dose-dependently inhibited STAT3 phosphorylation, reduced the expression of its downstream protein c-Myc and impeded the interaction between STAT3 molecules. CONCLUSIONS: These results suggest that diosmetin exerts anti-osteosarcoma effects by suppressing cell proliferation and inducing apoptosis via inhibiting the activation of STAT3/c-Myc signaling pathway, which provide the possibility for diosmetin to be a chemotherapeutic candidate for osteosarcoma.

Role of the JAK/STAT Pathway in Cervical Cancer: Its Relationship with HPV E6/E7 Oncoproteins.

The janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathway is associated with the regulation of essential cellular mechanisms, such as proliferation, invasion, survival, inflammation, and immunity. Aberrant JAK/STAT signaling contributes to cancer progression and metastatic development. STAT proteins play an essential role in the development of cervical cancer, and the inhibition of the JAK/STAT pathway may be essential for enhancing tumor cell death. Persistent activation of different STATs is present in a variety of cancers, including cervical cancer, and their overactivation may be associated with a poor prognosis and poor overall survival. The oncoproteins E6 and E7 play a critical role in the progression of cervical cancer and may mediate the activation of the JAK/STAT pathway. Inhibition of STAT proteins appears to show promise for establishing new targets in cancer treatment. The present review summarizes the knowledge about the participation of the different components of the JAK/STAT pathway and the participation of the human papillomavirus (HPV) associated with the process of cellular malignancy.

The potential role of sesquiterpene lactones isolated from medicinal plants in the treatment of the metabolic syndrome - A review.

Metabolic syndrome comprises a cluster of metabolic disorders related to the development of cardiovascular disease and type 2 diabetes mellitus. In latter years, plant secondary metabolites have become of special interest because of their potential role in preventing and managing metabolic syndrome. Sesquiterpene lactones constitute a large and diverse group of biologically active compounds widely distributed in several medicinal plants used for the treatment of metabolic disorders. The structural diversity and the broad spectrum of biological activities of these compounds drew significant interests in the pharmacological applications. This review describes selected sesquiterpene lactones that have been experimentally validated for their biological activities related to risk factors of metabolic syndrome, together with their mechanisms of action. The potential beneficial effects of sesquiterpene lactones discussed in this review demonstrate that these substances represent remarkable compounds with a diversity of molecular structure and high biological activity, providing new insights into the possible role in metabolic syndrome management.

Niclosamide attenuates lung vascular remodeling in experimental pulmonary arterial hypertension.

Despite advances in medical therapy, pulmonary arterial hypertension (PAH) remains an inexorably progressive and highly lethal disease. Signal transducer and activator of transcription (STAT)-3 is one of the main intracellular transcription factors implicated in PAH vascular remodeling. We hypothesized that niclosamide, a STAT3 inhibitor, would reduce vascular remodeling in an established pulmonary arterial hypertension model, thus enhancing cardiac function. Male Wistar rats were treated either with monocrotaline (60 mg/kg), to induce PAH, or saline (C group) by intraperitoneal injection. On day 14, PAH animals were randomly assigned to receive oral (1) saline (PAH-SAL); (2) niclosamide (75 mg/kg/day) (PAH-NICLO); (3) sildenafil (20 mg/kg/day) (PAH-SIL); or (4) niclosamide + sildenafil (PAH-NICLO + SIL), once daily for 14 days. On day 28, right ventricular systolic pressure was lower in all treated groups compared to PAH-SAL. Pulmonary vascular collagen content was lower in PAH-NICLO (37 ± 3%) and PAH-NICLO + SIL (37 ± 6%) compared to PAH-SAL (68 ± 4%), but not in PAH-SIL (52 ± 1%). CD-34, an endothelial cell marker, was higher, while vimentin, a mesenchymal cell marker, was lower in PAH-NICLO and PAH-NICLO + SIL compared to PAH-SAL, suggesting attenuation of endothelial-mesenchymal transition. Expression of STAT3 downstream targets such as transforming growth factor (TGF)-ß, hypoxia-inducible factor (HIF)-1, and provirus integration site for Moloney murine leukemia virus (PIM-1) in lung tissue was reduced in PAH-NICLO and PAH-NICLO + SIL compared to PAH-SAL. In conclusion, niclosamide, with or without sildenafil, mitigated vascular remodeling and improved right ventricle systolic pressure. This new role for a well-established drug may represent a promising therapy for PAH.

Changes in expression of interferon-stimulated genes and ubiquitin activating enzyme E1-like in ovine thymus during early pregnancy.

As the main signal for the maternal recognition in ruminants, interferon-tau (IFNT) stimulates expression of interferon-stimulated genes (ISGs) in uterus and many extrauterine tissues. However, it is unclear that early pregnancy induces expression of signal transducer and activator of transcription 1 (STAT1), myxovirusresistance 1 (Mx1), interferon-gamma-inducible protein 10 (IP-10) and ubiquitin activating enzyme E1-like protein (UBE1L) in maternal thymus. In this study, ovine thymuses were sampled on day 16 of the estrous cycle and on days 13, 16 and 25 of gestation, and the expression of STAT1, Mx1, IP-10 and UBE1L was detected by real-time quantitative PCR, Western blot and immunohistochemistry. The results revealed that the expression of STAT1 and IP-10 reached peaks on day 16 of pregnancy, and expression of Mx1 was enhanced on day 25 of pregnancy, and STAT1 protein was located in the epithelial reticular cells, capillaries and thymic corpuscles. However, expression of UBE1L was declined during early pregnancy. In conclusion, early pregnancy influences expression of STAT1, Mx1, IP-10 and UBE1L in maternal thymus, which may participate in regulation of maternal immune tolerance during early pregnancy in sheep.

Signal transducer and activator of transcription 6 as a target in colon cancer therapy.

Signal transducer and activator of transcription 6 (STAT6) is a member of the STAT family of proteins that serve key roles in the initiation of tumorigenesis and malignant transformation. STAT6 is highly expressed in several types of cancer, including breast, pancreatic, prostate and colorectal cancer. STAT6 transduces signals in response to the binding of interleukin (IL)-4 and IL-13 to their receptors and regulates the expression of genes involved in the immune response, cell survival, tumor proliferation and metastasis. Patients with colorectal cancer exhibit high STAT6 activity in the colonic epithelium, and STAT6 expression is associated with lower survival rates, lymph node metastasis, changes in the epithelial barrier function and alterations in the inflammatory response. A number of studies investigating experimental models and cancer cell lines have revealed that STAT6 is associated with tumor growth and development, as well as with increased invasion and metastasis, suggesting that STAT6 inhibition may serve as a novel therapeutic strategy in colon cancer. The present review summarizes the evidence with regard to the implications of STAT6 in cancer biology and the direct and indirect effects on colon tumor transformation. Furthermore, the current treatment strategies targeting the IL-4/IL-13/STAT6 axis in colon cancer are discussed.

Changes in expression of interferon-stimulated genes and ubiquitin activating enzyme E1-like in ovine thymus during early pregnancy

As the main signal for the maternal recognition in ruminants, interferon-tau (IFNT) stimulates expression of interferon-stimulated genes (ISGs) in uterus and many extrauterine tissues. However, it is unclear that early pregnancy induces expression of signal transducer and activator of transcription 1 (STAT1), myxovirusresistance 1 (Mx1), interferon-gamma-inducible protein 10 (IP-10) and ubiquitin activating enzyme E1-like protein (UBE1L) in maternal thymus. In this study, ovine thymuses were sampled on day 16 of the estrous cycle and on days 13, 16 and 25 of gestation, and the expression of STAT1, Mx1, IP-10 and UBE1L was detected by real-time quantitative PCR, Western blot and immunohistochemistry. The results revealed that the expression of STAT1 and IP-10 reached peaks on day 16 of pregnancy, and expression of Mx1 was enhanced on day 25 of pregnancy, and STAT1 protein was located in the epithelial reticular cells, capillaries and thymic corpuscles. However, expression of UBE1L was declined during early pregnancy. In conclusion, early pregnancy influences expression of STAT1, Mx1, IP-10 and UBE1L in maternal thymus, which may participate in regulation of maternal immune tolerance during early pregnancy in sheep.

Changes in expression of interferon-stimulated genes and ubiquitin activating enzyme E1-like in ovine thymus during early pregnancy

As the main signal for the maternal recognition in ruminants, interferon-tau (IFNT) stimulates expression of interferon-stimulated genes (ISGs) in uterus and many extrauterine tissues. However, it is unclear that early pregnancy induces expression of signal transducer and activator of transcription 1 (STAT1), myxovirusresistance 1 (Mx1), interferon-gamma-inducible protein 10 (IP-10) and ubiquitin activating enzyme E1-like protein (UBE1L) in maternal thymus. In this study, ovine thymuses were sampled on day 16 of the estrous cycle and on days 13, 16 and 25 of gestation, and the expression of STAT1, Mx1, IP-10 and UBE1L was detected by real-time quantitative PCR, Western blot and immunohistochemistry. The results revealed that the expression of STAT1 and IP-10 reached peaks on day 16 of pregnancy, and expression of Mx1 was enhanced on day 25 of pregnancy, and STAT1 protein was located in the epithelial reticular cells, capillaries and thymic corpuscles. However, expression of UBE1L was declined during early pregnancy. In conclusion, early pregnancy influences expression of STAT1, Mx1, IP-10 and UBE1L in maternal thymus, which may participate in regulation of maternal immune tolerance during early pregnancy in sheep.(AU)

Fish oil supplementation during adolescence attenuates metabolic programming of perinatal maternal high-fat diet in adult offspring.

Perinatal maternal high-fat diet (HFD) increases susceptibility to obesity and fatty liver diseases in adult offspring, which can be attenuated by the potent hypolipidaemic action of fish oil (FO), an n-3 PUFA source, during adult life. Previously, we described that adolescent HFD offspring showed resistance to FO hypolipidaemic effects, although FO promoted hepatic molecular changes suggestive of reduced lipid accumulation. Here, we investigated whether this FO intervention only during the adolescence period could affect offspring metabolism in adulthood. Then, female Wistar rats received isoenergetic, standard (STD: 9 % fat) or high-fat (HFD: 28·6 % fat) diet before mating, and throughout pregnancy and lactation. After weaning, male offspring received the standard diet; and from 25 to 45 d old they received oral administration of soyabean oil or FO. At 150 d old, serum and hepatic metabolic parameters were evaluated. Maternal HFD adult offspring showed increased body weight, visceral adiposity, hyperleptinaemia and decreased hepatic pSTAT3/STAT3 ratio, suggestive of hepatic leptin resistance. FO intake only during the adolescence period reduced visceral adiposity and serum leptin, regardless of maternal diet. Maternal HFD promoted dyslipidaemia and hepatic TAG accumulation, which was correlated with reduced hepatic carnitine palmitoyl transferase-1a content, suggesting lipid oxidation impairment. FO intake did not change serum lipids; however, it restored hepatic TAG content and hepatic markers of lipid oxidation to STD offspring levels. Therefore, we concluded that FO intake exclusively during adolescence programmed STD offspring and reprogrammed HFD offspring male rats to a healthier metabolic phenotype in adult life, reducing visceral adiposity, serum leptin and hepatic TAG content in offspring adulthood.

Inhibition of cancer stem cells promoted by Pimozide.

Over the past years, studies have described that users of antipsychotics are less likely to develop cancer than the population in general due to cytotoxic properties of this class of drugs on cancer cells. For this reason, Pimozide has been widely studied as a potential anticancer treatment, and satisfactory results in melanoma, central nervous system tumours, osteosarcoma, neuroblastoma, myeloproliferative neoplasms, breast, lung, prostate, ovarian, colorectal, pancreatic, and hepatocellular carcinoma have been showed. Moreover, advantages as clinical use approved by the Food and Drug Administration (FDA), high clinical safety, low side effects, and reasonable price have stimulated the treatment with Pimozide instead of other agents. The action mechanism remains unclear, but three vias associated to cancer stem cell (CSC) hypothesis show that Pimozide: (a) blocks CSC features, as epithelial-to-mesenchymal transition (EMT), through inhibition of Wnt-ß/catenin signalling; (b) acts as an inhibitor of signal transducer and activator of transcription (STAT-3 and 5), pathway which is activated and up-regulated in CSCs; (c) inhibits ubiquitine specific protease (USP1) and WD repeat-containing protein 48 (WDR48), that are proteins responsible to inhibit the differentiation and to maintain the cell in an undifferentiated state. Based on this perspective, the aim of this manuscript is to review the antineoplastic role of Pimozide during tumorigenesis and its potential to revert the process of undifferentiation and proliferation of CSC through different vias.

Interleukin-6 signalling mediates Galectin-8 co-stimulatory activity of antigen-specific CD4 T-cell response.

Galectin-8 (Gal-8) is a mammalian lectin endowed with the ability to co-stimulate antigen-specific immune responses. We have previously demonstrated that bone-marrow-derived dendritic cells produce high levels of interleukin-6 (IL-6) in response to Gal-8 stimulation. As IL-6 is a pleiotropic cytokine that has a broad effect on cells of the immune system, we aimed to elucidate whether IL-6 was involved in Gal-8-dependent co-stimulatory signals during antigen recognition by specific CD4 T cells. With this aim, splenocytes from DO11.10 mice were incubated with a low dose of the cognate ovalbumin peptide in combination with Gal-8. Interleukin-6 was found significantly increased in cultures stimulated with Gal-8 alone or Gal-8 plus cognate peptide. Moreover, IL-6 signalling was triggered during Gal-8-induced co-stimulation, as determined by phosphorylation of signal transducer and activator of transcription 3. Interleukin-6 blockade by neutralizing monoclonal antibody precluded Gal-8 co-stimulatory activity but did not affect the antigen-specific T-cell receptor activation. Different subsets of dendritic cells, as well as macrophages and B cells, were identified as the cellular source of IL-6 during Gal-8-induced co-stimulation. To confirm that IL-6 mediated the Gal-8 co-stimulatory effect, antigen-presenting cells from IL-6-deficient or wild-type mice were co-cultured with purified CD4 T cells from OTII mice in the presence of cognate peptide and Gal-8. Notably, Gal-8-induced co-stimulation, but not the antigen-specific response, was significantly impaired in the presence of IL-6-deficient antigen-presenting cells. In addition, exogenous IL-6 fully restored Gal-8-induced co-stimulation. Taken together, our results demonstrate that IL-6 signalling mediates the Gal-8 immune-stimulatory effect.

Melatonin Absence Leads to Long-Term Leptin Resistance and Overweight in Rats.

Melatonin (Mel), a molecule that conveys photoperiodic information to the organisms, is also involved in the regulation of energy homeostasis. Mechanisms of action of Mel in the energy balance remain unclear; herein we investigated how Mel regulates energy intake and expenditure to promote a proper energy balance. Male Wistar rats were assigned to control, control + Mel, pinealectomized (PINX) and PINX + Mel groups. To restore a 24-h rhythm, Mel (1 mg/kg) was added to the drinking water exclusively during the dark phase for 13 weeks. After this treatment period, rats were subjected to a 24-h fasting test, an acute leptin responsiveness test and cold challenge. Mel treatment reduced food intake, body weight, and adiposity. When challenged to 24-h fasting, Mel-treated rats also showed reduced hyperphagia when the food was replaced. Remarkably, PINX rats exhibited leptin resistance; this was likely related to the capacity of leptin to affect body weight, food intake, and hypothalamic signal-transducer and activator of transcription 3 phosphorylation, all of which were reduced. Mel treatment restored leptin sensitivity in PINX rats. An increased hypothalamic expression of agouti-related peptide (Agrp), neuropeptide Y, and Orexin was observed in the PINX group while Mel treatment reduced the expression of Agrp and Orexin. In addition, PINX rats presented lower UCP1 protein levels in the brown adipose tissue and required higher tail vasoconstriction to get a proper thermogenic response to cold challenge. Our findings reveal a previously unrecognized interaction of Mel and leptin in the hypothalamus to regulate the energy balance. These findings may help to explain the high incidence of metabolic diseases in individuals exposed to light at night.

Formation of Foamy Macrophages by Tuberculous Pleural Effusions Is Triggered by the Interleukin-10/Signal Transducer and Activator of Transcription 3 Axis through ACAT Upregulation.

The ability of Mycobacterium tuberculosis (Mtb) to persist in its human host relies on numerous immune evasion strategies, such as the deregulation of the lipid metabolism leading to the formation of foamy macrophages (FM). Yet, the specific host factors leading to the foamy phenotype of Mtb-infected macrophages remain unknown. Herein, we aimed to address whether host cytokines contribute to FM formation in the context of Mtb infection. Our approach is based on the use of an acellular fraction of tuberculous pleural effusions (TB-PE) as a physiological source of local factors released during Mtb infection. We found that TB-PE induced FM differentiation as observed by the increase in lipid bodies, intracellular cholesterol, and expression of the scavenger receptor CD36, as well as the enzyme acyl CoA:cholesterol acyl transferase (ACAT). Importantly, interleukin-10 (IL-10) depletion from TB-PE prevented the augmentation of all these parameters. Moreover, we observed a positive correlation between the levels of IL-10 and the number of lipid-laden CD14+ cells among the pleural cells in TB patients, demonstrating that FM differentiation occurs within the pleural environment. Downstream of IL-10 signaling, we noticed that the transcription factor signal transducer and activator of transcription 3 was activated by TB-PE, and its chemical inhibition prevented the accumulation of lipid bodies and ACAT expression in macrophages. In terms of the host immune response, TB-PE-treated macrophages displayed immunosuppressive properties and bore higher bacillary loads. Finally, we confirmed our results using bone marrow-derived macrophage from IL-10-/- mice demonstrating that IL-10 deficiency partially prevented foamy phenotype induction after Mtb lipids exposure. In conclusion, our results evidence a role of IL-10 in promoting the differentiation of FM in the context of Mtb infection, contributing to our understanding of how alterations of the host metabolic factors may favor pathogen persistence.

A 3-Year-Old Girl with Recurrent Infections and Autoimmunity due to a STAT1 Gain-of-Function Mutation: The Expanding Clinical Presentation of Primary Immunodeficiencies.

We report a 3-year-old Peruvian girl, born to non-consanguineous parents. At the age of 8 months, she had a severe pneumonia complicated with empyema that required thoracic drainage and mechanical ventilation. Although no microorganisms were isolated, the patient recovered with broad-spectrum antibiotics. Since that date, she has presented multiple episodes of pneumonia and recurrent episodes of bronchospasm. At 1 year 5 months of age, the patient began with recurrent episodes of oropharyngeal, vaginal, and skin candidiasis, which improved transiently after using oral azole drugs. At 2.5 years of age, she was admitted with lupus-like syndrome, including serositis, hemolytic anemia, thrombocytopenia, and positive antinuclear (1:80) and dsDNA (1:10) autoantibodies. Available immunologic testing was not contributory. Imaging studies revealed bilateral ethmoidal sinusitis and mild hepatomegaly. Bone marrow analysis did not showed evidence of leukemia or myelodysplasia, while renal biopsy concluded mild mesangial proliferation. Genetic studies revealed a pathogenic heterozygous signal transducer and activator of transcription 1 gain-of-function mutation (WT/P293L). The clinical status and lung function of the patient has worsened progressively. She has not achieved an optimal response to therapy, including high-dose intravenous immunoglobulin, GM-CSF, prophylactic antibiotics and antifungal drugs, so we plan to perform hematopoietic stem cell transplantation.

SOCS3 deficiency in leptin receptor-expressing cells mitigates the development of pregnancy-induced metabolic changes.

OBJECTIVE: During pregnancy, women normally increase their food intake and body fat mass, and exhibit insulin resistance. However, an increasing number of women are developing metabolic imbalances during pregnancy, including excessive gestational weight gain and gestational diabetes mellitus. Despite the negative health impacts of pregnancy-induced metabolic imbalances, their molecular causes remain unclear. Therefore, the present study investigated the molecular mechanisms responsible for orchestrating the metabolic changes observed during pregnancy. METHODS: Initially, we investigated the hypothalamic expression of key genes that could influence the energy balance and glucose homeostasis during pregnancy. Based on these results, we generated a conditional knockout mouse that lacks the suppressor of cytokine signaling-3 (SOCS3) only in leptin receptor-expressing cells and studied these animals during pregnancy. RESULTS: Among several genes involved in leptin resistance, only SOCS3 was increased in the hypothalamus of pregnant mice. Remarkably, SOCS3 deletion from leptin receptor-expressing cells prevented pregnancy-induced hyperphagia, body fat accumulation as well as leptin and insulin resistance without affecting the ability of the females to carry their gestation to term. Additionally, we found that SOCS3 conditional deletion protected females against long-term postpartum fat retention and streptozotocin-induced gestational diabetes. CONCLUSIONS: Our study identified the increased hypothalamic expression of SOCS3 as a key mechanism responsible for triggering pregnancy-induced leptin resistance and metabolic adaptations. These findings not only help to explain a common phenomenon of the mammalian physiology, but it may also aid in the development of approaches to prevent and treat gestational metabolic imbalances.