CLCA1 is Poorly Expressed in Stomach Adenocarcinoma and Correlates with Immune Infiltration / CLCA1 se Expresa Deficientemente en el Adenocarcinoma de Estómago y se Correlaciona con la Infiltración Inmune

SUMMARY: Calcium-activated chloride channel regulator 1 (CLCA1) is associated with cancer progression. The expression and immunologic function of CLCA1 in stomach adenocarcinoma (STAD) remain unclear. In this investigation, the expression of CLCA1 in STAD tissues and its involvement in the progression and immune response of STAD were examined using databases such as cBioPortal, TISIDB, and UALCAN. In order to validate the expression level of CLCA1 protein in gastric adenocarcinoma, thirty clinical tissue specimens were gathered for immunohistochemical staining. The findings indicated a downregulation of CLCA1 in STAD patients, which was correlated with race, age, cancer grade, Helicobacter pylori infection, and molecular subtype. Through the examination of survival analysis, it was identified that diminished levels of CLCA1 within gastric cancer cases were linked to decreased periods of post-progression survival (PPS), overall survival (OS), and first progression (FP) (P<0.05). The CLCA1 mutation rate was lower in STAD, but the survival rate was higher in the variant group. The correlation between the expression level of CLCA1 and the levels of immune infiltrating cells in STAD, as well as the immune activating molecules, immunosuppressive molecules, MHC molecules, chemokines, and their receptor molecules, was observed. Gene enrichment analysis revealed that CLCA1 may be involved in STAD progression through systemic lupus erythematosus (SLE), proteasome, cell cycle, pancreatic secretion, and PPAR signaling pathways. In summary, CLCA1 is anticipated to function as a prognostic marker for patients with STAD and is linked to the immunization of STAD.

El regulador 1 del canal de cloruro activado por calcio (CLCA1) está asociado con la progresión del cáncer. La expresión y la función inmunológica de CLCA1 en el adenocarcinoma de estómago (STAD) aún no están claras. En esta investigación, se examinó la expresión de CLCA1 en tejidos STAD y su participación en la progresión y respuesta inmune de STAD utilizando bases de datos como cBioPortal, TISIDB y UALCAN. Para validar el nivel de expresión de la proteína CLCA1 en el adenocarcinoma gástrico, se recolectaron treinta muestras de tejido clínico para tinción inmunohistoquímica. Los hallazgos indicaron una regulación negativa de CLCA1 en pacientes con STAD, que se correlacionó con la raza, la edad, el grado del cáncer, la infección por Helicobacter pylori y el subtipo molecular. Mediante el examen del análisis de supervivencia, se identificó que los niveles reducidos de CLCA1 en los casos de cáncer gástrico estaban relacionados con períodos reducidos de supervivencia posterior a la progresión (PPS), supervivencia general (OS) y primera progresión (FP) (P <0,05). La tasa de mutación CLCA1 fue menor en STAD, pero la tasa de supervivencia fue mayor en el grupo variante. Se observó la correlación entre el nivel de expresión de CLCA1 y los niveles de células inmunes infiltrantes en STAD, así como las moléculas activadoras inmunes, moléculas inmunosupresoras, moléculas MHC, quimiocinas y sus moléculas receptoras. El análisis de enriquecimiento genético reveló que CLCA1 puede estar involucrado en la progresión de STAD a través del lupus eritematoso sistémico (LES), el proteasoma, el ciclo celular, la secreción pancreática y las vías de señalización de PPAR. En resumen, se prevé que CLCA1 funcione como un marcador de pronóstico para pacientes con STAD y está vinculado a la inmunización de STAD.

Comprehensive Analysis of CLCA1 Expression, Immune Infiltration and Immune Checkpoints in Colon Adenocarcinoma / Análisis Completo de la Expresión de CLCA1, Infiltración Inmune y Puntos de Control Inmunológico en Colonadenocarcinoma

SUMMARY: Colon adenocarcinoma (COAD) is a prevalent disease worldwide, known for its high mortality and morbidity rates. Despite this, the extent of investigation concerning the correlation between COAD's CLCA1 expression and immune cell infiltration remains insufficient. This study seeks to examine the expression and prognosis of CLCA1 in COAD, along with its relationship to the tumor immune microenvironment. These findings will offer valuable insights for clinical practitioners and contribute to the existing knowledge in the field. In order to evaluate the prognostic significance of CLCA1 in individuals diagnosed with colorectal cancers, we conducted a comprehensive analysis using univariate and multivariate Cox regression models along with receiver operating characteristic curve (ROC) analysis. This study was performed on the patient data of COAD obtained from The Cancer Genome Atlas (TCGA) database. Nomograms were developed to anticipate CLCA1 prognostic influence. Furthermore, the CLCA1 association with tumor immune infiltration, immune checkpoints, immune checkpoint blockade (ICB) response, interaction network, and functional analysis of CLCA1-related genes was analyzed. We found that Colon adenocarcinoma tissues significantly had decreased CLCA1 expression compared to healthy tissues. Furthermore, the study revealed that the group with high expression of CLCA1 demonstrated a significantly higher overall survival rate (OS) as compared to the group with low expression. Multivariate and Univariate Cox regression analysis revealed the potential of CLCA1 as a standalone risk factor for COAD. These results were confirmed using nomograms and ROC curves. In addition, protein-protein interaction (PPI) network analysis and functional gene enrichment showed that CLCA1 may be associated with functional activities such as pancreatic secretion, estrogen signaling and cAMP signaling, as well as with specific immune cell infiltration. Therefor, as a new independent predictor and potential biomarker of COAD, CLCA1 plays a crucial role in the advancement of colon cancer.

El adenocarcinoma de colon (COAD) es una enfermedad prevalente a nivel mundial, conocida por sus altas tasas de mortalidad y morbilidad. Sin embargo, el alcance de la investigación sobre la correlación entre la expresión de CLCA1 de COAD y la infiltración de células inmunes sigue siendo insuficiente. Este estudio busca examinar la expresión y el pronóstico de CLCA1 en COAD, junto con su relación con el microambiente inmunológico del tumor. Estos hallazgos ofrecerán conocimientos valiosos para los profesionales clínicos y contribuirán al conocimiento existente en el campo. Para evaluar la importancia de pronóstico de CLCA1 en personas diagnosticadas con cáncer colorrectal, realizamos un análisis exhaustivo utilizando modelos de regresión de Cox univariados y multivariados junto con un análisis de la curva característica operativa del receptor (ROC). Este estudio se realizó con los datos de pacientes de COAD obtenidos de la base de datos The Cancer Genome Atlas (TCGA). Se desarrollaron nomogramas para anticipar la influencia pronóstica de CLCA1. Además, se analizó la asociación de CLCA1 con la infiltración inmunitaria tumoral, los puntos de control inmunitarios, la respuesta de bloqueo de los puntos de control inmunitarios (ICB), la red de interacción y el análisis funcional de genes relacionados con CLCA1. Descubrimos que los tejidos de adenocarcinoma de colon tenían una expresión significativamente menor de CLCA1 en comparación con los tejidos sanos. Además, el estudio reveló que el grupo con alta expresión de CLCA1 demostró una tasa de supervivencia general (SG) significativamente mayor en comparación con el grupo con baja expresión. El análisis de regresión de Cox multivariado y univariado reveló el potencial de CLCA1 como factor de riesgo independiente de COAD. Estos resultados se confirmaron mediante nomogramas y curvas ROC. Además, el análisis de la red de interacción proteína- proteína (PPI) y el enriquecimiento de genes funcionales mostraron que CLCA1 puede estar asociado con actividades funcionales como la secreción pancreática, la señalización de estrógenos y la señalización de AMPc, así como con la infiltración de células inmunes específicas. Por lo tanto, como nuevo predictor independiente y biomarcador potencial de COAD, CLCA1 desempeña un papel crucial en el avance del cáncer de colon.

A study of innate immune kinetics reveals a role for a chloride transporter in a virulent Francisella tularensis type B strain.

Tularemia is a zoonotic disease of global proportions. Francisella tularensis subspecies tularensis (type A) and holarctica (type B) cause disease in healthy humans, with type A infections resulting in higher mortality. Repeated passage of a type B strain in the mid-20th century generated the Live Vaccine Strain (LVS). LVS remains unlicensed, does not protect against high inhalational doses of type A, and its exact mechanisms of attenuation are poorly understood. Recent data suggest that live attenuated vaccines derived from type B may cross-protect against type A. However, there is a dearth of knowledge regarding virulent type B pathogenesis and its capacity to stimulate the host's innate immune response. We therefore sought to increase our understanding of virulent type B in vitro characteristics using strain OR96-0246 as a model. Adding to our knowledge of innate immune kinetics in macrophages following infection with virulent type B, we observed robust replication of strain OR96-0246 in murine and human macrophages, reduced expression of pro-inflammatory cytokine genes from "wild type" type B-infected macrophages compared to LVS, and delayed macrophage cell death suggesting that virulent type B may suppress macrophage activation. One disruption in LVS is in the gene encoding the chloride transporter ClcA. We investigated the role of ClcA in macrophage infection and observed a replication delay in a clcA mutant. Here, we propose its role in acid tolerance. A greater understanding of LVS attenuation may reveal new mechanisms of pathogenesis and inform strategies toward the development of an improved vaccine against tularemia.

ATP-Gated P2X7 Receptors Require Chloride Channels To Promote Inflammation in Human Macrophages.

Immune cells of myeloid origin show robust expression of ATP-gated P2X7 receptors, two-transmembrane ion channels permeable to Na+, K+, and Ca2+ Receptor activation promotes inflammasome activation and release of the proinflammatory cytokines IL-1ß and IL-18. In this study, we show that ATP generates facilitating cationic currents in monocyte-derived human macrophages and permeabilizes the plasma membrane to polyatomic cationic dyes. We find that antagonists of PLA2 and Cl- channels abolish P2X7 receptor-mediated current facilitation, membrane permeabilization, blebbing, phospholipid scrambling, inflammasome activation, and IL-1ß release. Our data demonstrate significant differences in the actions of ATP in murine and human macrophages and suggest that PLA2 and Cl- channels mediate innate immunity downstream of P2X7 receptors in human macrophages.

Antiviral innate immune response in non-myeloid cells is augmented by chloride ions via an increase in intracellular hypochlorous acid levels.

Phagocytes destroy ingested microbes by producing hypochlorous acid (HOCl) from chloride ions (Cl-) and hydrogen peroxide within phagolysosomes, using the enzyme myeloperoxidase. HOCl, the active ingredient in bleach, has antibacterial/antiviral properties. As myeloperoxidase is needed for HOCl production, non-myeloid cells are considered incapable of producing HOCl. Here, we show that epithelial, fibroblast and hepatic cells have enhanced antiviral activity in the presence of increasing concentrations of sodium chloride (NaCl). Replication of enveloped/non-enveloped, DNA (herpes simplex virus-1, murine gammaherpesvirus 68) and RNA (respiratory syncytial virus, influenza A virus, human coronavirus 229E, coxsackievirus B3) viruses are inhibited in a dose-dependent manner. Whilst treatment with sodium channel inhibitors did not prevent NaCl-mediated virus inhibition, a chloride channel inhibitor reversed inhibition by NaCl, suggesting intracellular chloride is required for antiviral activity. Inhibition is also reversed in the presence of 4-aminobenzoic hydrazide, a myeloperoxidase inhibitor, suggesting epithelial cells have a peroxidase to convert Cl- to HOCl. A significant increase in intracellular HOCl production is seen early in infection. These data suggest that non-myeloid cells possess an innate antiviral mechanism dependent on the availability of Cl- to produce HOCl. Antiviral activity against a broad range of viral infections can be augmented by increasing availability of NaCl.

MtHsp70-CLIC1-pulsed dendritic cells enhance the immune response against ovarian cancer.

Approximately 80% of ovarian cancer (OC) is diagnosed at late stages, and most patients die within 5 years of diagnosis due to recurrence or drug resistance. Novel treatments are required to improve patient survival. Immune therapy against cancer is promising; however, therapeutic vaccination has been limited by the inability of tumor antigens to induce effective immune responses. Chloride intracellular channel 1 (CLIC1) was previously identified as a possible tumor marker for OC. In this study, we constructed a recombinant protein by conjugating the extracellular domain of CLIC1 to the carboxyl terminus of Mycobacterium tuberculosis heat shock protein 70 (MtHsp70). Human dendritic cells (DCs) derived from cortical blood were pulsed with the fusion protein, and the antitumor effect of human cytotoxic T lymphocytes (CTLs) stimulated by autologous DCs was assessed in NOG mice. MtHsp70-CLIC1 promoted the phenotypic maturation of human DCs and the secretion of Th1-associated cytokines in vitro. MtHsp70-CLIC1-stimulated CTLs generated a CLIC1-specific immune response both in vitro and in vivo. These results indicate that DCs pulsed with MtHsp70-CLIC1 can enhance antitumor immunity against OC, providing a novel immune therapeutic strategy.

Association of anti-CLIC2 and anti-HMGB1 autoantibodies with higher disease activity in systemic lupus erythematosus patients.

BACKGROUND: Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by numerous autoantibodies. In this study, we investigated the presence of anti-chloride intracellular channel 2 (anti-CLIC2) and anti-high mobility group box 1 (anti-HMGB1) autoantibodies in SLE patients (n = 43) versus healthy controls ([HCs] n = 43), and their association with serological parameters (antinuclear antibody [ANA], anti-double-stranded DNA [anti-dsDNA], and C-reactive protein [CRP]) and disease activity using Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) score (active or inactive). SETTINGS AND DESIGN: Case-control study at Rheumatology Clinic of Universiti Sains Malaysia Hospital. SUBJECTS AND METHODS: The sera of SLE patients and HCs were tested for the presence of anti-CLIC2 and anti-HMGB1 autoantibodies using human recombinant proteins and ELISA methodologies. Other serological parameters were evaluated according to routine procedures, and patients' demographic and clinical data were obtained. STATISTICAL ANALYSIS: Mann-Whitney U-test, Chi-square test, Fisher's exact test, and receiver operating characteristic analysis. RESULTS: Anti-CLIC2 autoantibody levels were significantly higher in SLE patients compared to HCs (P = 0.0035), whereas anti-HMGB1 autoantibody levels were not significantly elevated (P = 0.7702). Anti-CLIC2 and anti-HMGB1 autoantibody levels were not associated with ANA pattern, anti-dsDNA, and CRP. Interestingly, SLEDAI score (≥6) was associated with anti-CLIC2 (P = 0.0046) and with anti-HMGB1 (P = 0.0091) autoantibody levels. CONCLUSION: Our findings support the potential of using anti-CLIC2 autoantibodies as a novel biomarker for SLE patients. Both anti-CLIC2 and anti-HMGB1 autoantibody levels demonstrated potential in monitoring SLE disease activity.

TMEM16A/ANO1 suppression improves response to antibody-mediated targeted therapy of EGFR and HER2/ERBB2.

TMEM16A, a Ca2+ -activated Cl- channel, contributes to tumor growth in breast cancer and head and neck squamous cell carcinoma (HNSCC). Here, we investigated whether TMEM16A influences the response to EGFR/HER family-targeting biological therapies. Inhibition of TMEM16A Cl- channel activity in breast cancer cells with HER2 amplification induced a loss of viability. Cells resistant to trastuzumab, a monoclonal antibody targeting HER2, showed an increase in TMEM16A expression and heightened sensitivity to Cl- channel inhibition. Treatment of HNSCC cells with cetuximab, a monoclonal antibody targeting EGFR, and simultaneous TMEM16A suppression led to a pronounced loss of viability. Biochemical analyses of cells subjected to TMEM16A inhibitors or expressing chloride-deficient forms of TMEM16A provide further evidence that TMEM16A channel function may play a role in regulating EGFR/HER2 signaling. These data demonstrate that TMEM16A regulates EGFR and HER2 in growth and survival pathways. Furthermore, in the absence of TMEM16A cotargeting, tumor cells may acquire resistance to EGFR/HER inhibitors. Finally, targeting TMEM16A improves response to biological therapies targeting EGFR/HER family members.

CD8+ T cells stimulate Na-Cl co-transporter NCC in distal convoluted tubules leading to salt-sensitive hypertension.

Recent studies suggest a role for T lymphocytes in hypertension. However, whether T cells contribute to renal sodium retention and salt-sensitive hypertension is unknown. Here we demonstrate that T cells infiltrate into the kidney of salt-sensitive hypertensive animals. In particular, CD8+ T cells directly contact the distal convoluted tubule (DCT) in the kidneys of DOCA-salt mice and CD8+ T cell-injected mice, leading to up-regulation of the Na-Cl co-transporter NCC, p-NCC and the development of salt-sensitive hypertension. Co-culture with CD8+ T cells upregulates NCC in mouse DCT cells via ROS-induced activation of Src kinase, up-regulation of the K+ channel Kir4.1, and stimulation of the Cl- channel ClC-K. The last event increases chloride efflux, leading to compensatory chloride influx via NCC activation at the cost of increasing sodium retention. Collectively, these findings provide a mechanism for adaptive immunity involvement in the kidney defect in sodium handling and the pathogenesis of salt-sensitive hypertension.

Abrogating ClC-3 Inhibits LPS-induced Inflammation via Blocking the TLR4/NF-κB Pathway.

This study investigated the function of a chloride channel blocker, DIDS. Both in vitro and in vivo studies found that DIDS significantly inhibits lipopolysaccharide (LPS)-induced release of proin flammatory cytokines. Here, we show that DIDS inhibits LPS-induced inflammation, as shown by downregulation of inflammatory cytokines via inhibition of the TLR4/NF-κB pathway. Furthermore, we show that ClC-3siRNA transfection reduces LPS-induced pro-inflammation in Raw264.7 cells, indicating that ClC-3 is involved in the inhibitory effect of DIDS during LPS-induced cytokines release. In vivo, DIDS reduced LPS-induced mortality, decreased LPS-induced organic damage, and down-regulated LPS-induced expression of inflammatory cytokines. In sum, we demonstrate that ClC-3 is a pro-inflammatory factor and that inhibition of ClC-3 inhibits inflammatory induction both in vitro and in vivo, suggesting that ClC-3 is a potential anti-inflammatory target.

The Lymphatic Endothelial mCLCA1 Antibody Induces Proliferation and Growth of Lymph Node Lymphatic Sinuses.

Lymphocyte- and leukocyte-mediated lymph node (LN) lymphatic sinus growth (lymphangiogenesis) is involved in immune responses and in diseases including cancer and arthritis. We previously discovered a 10.1.1 Ab that recognizes the lymphatic endothelial cell (LEC) surface protein mCLCA1, which is an interacting partner for LFA1 and Mac-1 that mediates lymphocyte adhesion to LECs. Here, we show that 10.1.1 Ab treatment specifically induces LEC proliferation, and influences migration and adhesion in vitro. Functional testing by injection of mice with 10.1.1 Ab but not control hamster Abs identified rapid induction of LN LEC proliferation and extensive lymphangiogenesis within 23 h. BrdU pulse-chase analysis demonstrated incorporation of proliferating LYVE-1-positive LEC into the growing medullary lymphatic sinuses. The 10.1.1 Ab-induced LN remodeling involved coordinate increases in LECs and also blood endothelial cells, fibroblastic reticular cells, and double negative stroma, as is observed during the LN response to inflammation. 10.1.1 Ab-induced lymphangiogenesis was restricted to LNs, as mCLCA1-expressing lymphatic vessels of the jejunum and dermis were unaffected by 23 h 10.1.1 Ab treatment. These findings demonstrate that 10.1.1 Ab rapidly and specifically induces proliferation and growth of LN lymphatic sinuses and stroma, suggesting a key role of mCLCA1 in coordinating LN remodeling during immune responses.

Acidic chitinase primes the protective immune response to gastrointestinal nematodes.

Acidic mammalian chitinase (AMCase) is known to be induced by allergens and helminths, yet its role in immunity is unclear. Using AMCase-deficient mice, we show that AMCase deficiency reduced the number of group 2 innate lymphoid cells during allergen challenge but was not required for establishment of type 2 inflammation in the lung in response to allergens or helminths. In contrast, AMCase-deficient mice showed a profound defect in type 2 immunity following infection with the chitin-containing gastrointestinal nematodes Nippostrongylus brasiliensis and Heligmosomoides polygyrus bakeri. The impaired immunity was associated with reduced mucus production and decreased intestinal expression of the signature type 2 response genes Il13, Chil3, Retnlb, and Clca1. CD103(+) dendritic cells, which regulate T cell homing, were also reduced in mesenteric lymph nodes of infected AMCase-deficient mice. Thus, AMCase functions as a critical initiator of protective type 2 responses to intestinal nematodes but is largely dispensable for allergic responses in the lung.

Anoctamin 2 identified as an autoimmune target in multiple sclerosis.

Multiple sclerosis (MS) is the most common chronic inflammatory disease of the central nervous system and also is regarded as an autoimmune condition. However, the antigenic targets of the autoimmune response in MS have not yet been deciphered. In an effort to mine the autoantibody repertoire within MS, we profiled 2,169 plasma samples from MS cases and population-based controls using bead arrays built with 384 human protein fragments selected from an initial screening with 11,520 antigens. Our data revealed prominently increased autoantibody reactivity against the chloride-channel protein anoctamin 2 (ANO2) in MS cases compared with controls. This finding was corroborated in independent assays with alternative protein constructs and by epitope mapping with peptides covering the identified region of ANO2. Additionally, we found a strong interaction between the presence of ANO2 autoantibodies and the HLA complex MS-associated DRB1*15 allele, reinforcing a potential role for ANO2 autoreactivity in MS etiopathogenesis. Furthermore, immunofluorescence analysis in human MS brain tissue showed ANO2 expression as small cellular aggregates near and inside MS lesions. Thus this study represents one of the largest efforts to characterize the autoantibody repertoire within MS. The findings presented here demonstrate that an ANO2 autoimmune subphenotype may exist in MS and lay the groundwork for further studies focusing on the pathogenic role of ANO2 autoantibodies in MS.

Is DOG1 Immunoreactivity Specific to Gastrointestinal Stromal Tumor?

BACKGROUND: DOG1 is a novel gene on gastrointestinal stromal tumors (GISTs) that encodes the chloride channel protein anoctamin 1, also known as discovered on GIST-1 (DOG1) protein. DOG1 antibodies are a sensitive and specific marker against GIST positive for CD117 and CD34 and negative for CD117 and CD34. DOG1 is also independent of KIT or PDGFRA mutation status and considered specific for GIST when it was first discovered in 2004. METHODS: The previous 10 years of literature was searched for articles relating to DOG1. We critically reviewed 12 studies that showed DOG1 was positive in 250 cases of 2,360 tested non-GIST neoplasms (10.6%) at different anatomical sites using monoclonal, polyclonal, or nonspecified antibodies. Criteria for positivity varied between the studies. RESULTS: Monoclonal and polyclonal DOG1 antibodies were reactive in various different non-GIST tumor types spanning 9 organ systems in addition to normal salivary and pancreatic tissues. The tumors included were renal oncocytoma (100%), renal cell carcinoma chromophobe type (86%), solid pseudopapillary neoplasm of the pancreas (51%), neoplastic salivary tissue (17%), synovial sarcoma (15%), leiomyoma (10%), pancreatic adenocarcinoma (7%), and leiomyosarcoma (4%). CONCLUSIONS: By contrast to the original concept that DOG1 antibodies are specific to GIST neoplasms, the studies reviewed showed that the data suggest DOG1 positivity in select non-GIST tumors. Only in the appropriate clinical and pathological context is DOG1 positivity specific and helpful in the diagnosis of GIST.

Mosquitocidal properties of IgG targeting the glutamate-gated chloride channel in three mosquito disease vectors (Diptera: Culicidae).

The glutamate-gated chloride channel (GluCl) is a highly sensitive insecticide target of the avermectin class of insecticides. As an alternative to using chemical insecticides to kill mosquitoes, we tested the effects of purified immunoglobulin G (IgG) targeting the extracellular domain of GluCl from Anopheles gambiae (AgGluCl) on the survivorship of three key mosquito disease vectors: Anopheles gambiae s.s., Aedes aegypti and Culex tarsalis. When administered through a single blood meal, anti-AgGluCl IgG reduced the survivorship of A. gambiae in a dose-dependent manner (LC50: 2.82 mg ml(-1), range 2.68-2.96 mg ml(-1)) but not A. aegypti or C. tarsalis. We previously demonstrated that AgGluCl is only located in tissues of the head and thorax of A. gambiae. To verify that AgGluCl IgG is affecting target antigens found outside the midgut, we injected it directly into the hemocoel via intrathoracic injection. A single, physiologically relevant concentration of anti-AgGluCl IgG injected into the hemocoel equally reduced mosquito survivorship of all three species. To test whether anti-AgGluCl IgG was entering the hemocoel of each of these mosquitoes, we fed mosquitoes a blood meal containing anti-AgGluCl IgG and subsequently extracted their hemolymph. We only detected IgG in the hemolymph of A. gambiae, suggesting that resistance of A. aegypti and C. tarsalis to anti-AgGluCl IgG found in blood meals is due to deficient IgG translocation across the midgut. We predicted that anti-AgGluCl IgG's mode of action is by antagonizing GluCl activity. To test this hypothesis, we fed A. gambiae blood meals containing anti-AgGluCl IgG and the GluCl agonist ivermectin (IVM). Anti-AgGluCl IgG attenuated the mosquitocidal effects of IVM, suggesting that anti-AgGluCl IgG antagonizes IVM-induced activation of GluCl. Lastly, we stained adult, female A. aegypti and C. tarsalis for GluCl expression. Neuronal GluCl expression in these mosquitoes was similar to previously reported A. gambiae GluCl expression; however, we also discovered GluCl staining on the basolateral surface of their midgut epithelial cells, suggesting important physiological differences in Culicine and Anopheline mosquitoes.

Identification of novel immune phenotypes for allergic and nonallergic childhood asthma.

BACKGROUND: Childhood asthma is classified into allergic asthma (AA) and nonallergic asthma (NA), yet both are treated identically, with only partial success. OBJECTIVE: We sought to identify novel immune phenotypes for childhood AA and NA. METHODS: The Clinical Asthma Research Association cohort study includes 275 steroid-naive 4- to 15-year-old German children (healthy control subjects [HCs], patients with AA, and patients with NA). In PBMCs both quantitative and functional analysis of regulatory T (Treg) and TH17 cells (flow cytometry/Treg cell suppression) before/after anti-CD3/CD28, lipid A, and peptidoglycan stimulation were performed. Cytokines and gene expression, as assessed by using Luminex or transcriptomics/quantitative real-time RT-PCR, were analyzed by means of regression analysis. Linear discriminant analysis was applied to discriminate between phenotypes. RESULTS: The 3 phenotypes were immunologically well discriminated by means of microarray and protein analysis with linear discriminant analysis. Patients with AA were characterized by increased Treg cells compared with those in HCs but not those in patients with NA. Treg cells from patients with AA, but not patients with NA, significantly suppressed IL-5, IL-13, and IFN-γ secretion. Patients with AA had decreased expression of chloride intracellular channel 4 (CLIC4) and tuberous sclerosis 1 (TSC1), important innate immunity regulators. Patients with NA were characterized by increased proinflammatory IL-1ß levels, neutrophil counts, and IL-17-shifted immunity. In parallel, expressions of anti-inflammatory IL37, proline-serine-threonine phosphatase-interacting protein 2 (PSTPIP2), and the neutrophil-associated genes CD93, triggering receptor expressed on myeloid cells 1 (TREM1), and regulator of G-protein signaling 13 (RGS13) were increased in patients with NA. A shared TH2 immunity was present in both asthma phenotypes. CONCLUSION: Novel immune-regulatory mechanisms in childhood asthma identified increased Treg cells in patients with AA compared with those in HCs but not those in NA and decreased innate immunity genes for patients with AA, the first potentially indicating a counterregulatory mechanism to suppress cytokines yet not sufficient to control allergic inflammation. Very distinctly, patients with NA showed an IL-17-shifted proinflammatory immunity, promoting neutrophil inflammation and less functional Treg cells. Identification of these unique pathways provides a profound basis for future strategies for individualized prediction of asthma development, disease course, and prevention.

Structure and insights into the function of a Ca(2+)-activated Cl(-) channel.

Bestrophin calcium-activated chloride channels (CaCCs) regulate the flow of chloride and other monovalent anions across cellular membranes in response to intracellular calcium (Ca(2+)) levels. Mutations in bestrophin 1 (BEST1) cause certain eye diseases. Here we present X-ray structures of chicken BEST1-Fab complexes, at 2.85 Å resolution, with permeant anions and Ca(2+). Representing, to our knowledge, the first structure of a CaCC, the eukaryotic BEST1 channel, which recapitulates CaCC function in liposomes, is formed from a pentameric assembly of subunits. Ca(2+) binds to the channel's large cytosolic region. A single ion pore, approximately 95 Å in length, is located along the central axis and contains at least 15 binding sites for anions. A hydrophobic neck within the pore probably forms the gate. Phenylalanine residues within it may coordinate permeating anions via anion-π interactions. Conformational changes observed near the 'Ca(2+) clasp' hint at the mechanism of Ca(2+)-dependent gating. Disease-causing mutations are prevalent within the gating apparatus.

mCLCA3 modulates IL-17 and CXCL-1 induction and leukocyte recruitment in murine Staphylococcus aureus pneumonia.

The human hCLCA1 and its murine ortholog mCLCA3 (calcium-activated chloride channel regulators) are exclusively expressed in mucus cells and linked to inflammatory airway diseases with increased mucus production, such as asthma, cystic fibrosis and chronic obstructive pulmonary disease. Both proteins have a known impact on the mucus cell metaplasia trait in these diseases. However, growing evidence points towards an additional role in innate immune responses. In the current study, we analyzed Staphylococcus aureus pneumonia, an established model to study pulmonary innate immunity, in mCLCA3-deficient and wild-type mice, focusing on the cellular and cytokine-driven innate inflammatory response. We compared clinical signs, bacterial clearance, leukocyte immigration and cytokine responses in the bronchoalveolar compartment, as well as pulmonary vascular permeability, histopathology, mucus cell number and mRNA expression levels of selected genes (mClca1 to 7, Muc5ac, Muc5b, Muc2, Cxcl-1, Cxcl-2, Il-17). Deficiency of mCLCA3 resulted in decreased neutrophilic infiltration into the bronchoalveolar space during bacterial infection. Only the cytokines IL-17 and the murine CXCL-8 homolog CXCL-1 were decreased on mRNA and protein levels during bacterial infection in mCLCA3-deficient mice compared to wild-type controls. However, no differences in clinical outcome, histopathology or mucus cell metaplasia were observed. We did not find evidence for regulation of any other CLCA homolog that would putatively compensate for the lack of mCLCA3. In conclusion, mCLCA3 appears to modulate leukocyte response via IL-17 and murine CXCL-8 homologs in acute Staphylococcus aureus pneumonia which is well in line with the proposed function of hCLCA1 as a signaling molecule acting on alveolar macrophages.

CLIC1 functional expression is required for cAMP-induced neurite elongation in post-natal mouse retinal ganglion cells.

During neuronal differentiation, axonal elongation is regulated by both external and intrinsic stimuli, including neurotropic factors, cytoskeleton dynamics, second messengers such as cyclic adenosine monophosphate (cAMP), and neuronal excitability. Chloride intracellular channel 1 (CLIC1) is a cytoplasmic hydrophilic protein that, upon stimulation, dimerizes and translocates to the plasma membrane, where it contributes to increase the membrane chloride conductance. Here, we investigated the expression of CLIC1 in primary hippocampal neurons and retinal ganglion cells (RGCs) and examined how the functional expression of CLIC1 specifically modulates neurite outgrowth of neonatal murine RGCs. Using a combination of electrophysiology and immunohistochemistry, we found that CLIC1 is expressed in hippocampal neurons and RGCs and that the chloride current mediated by CLIC1 is required for maintaining growth cone morphology and sustaining cAMP-stimulated neurite elongation in dissociated immunopurified RGCs. In cultured RGCs, inhibition of CLIC1 ionic current through the pharmacological blocker IAA94 or a specific anti-CLIC1 antibody directed against its extracellular domain prevents the neurite outgrowth induced by cAMP. CLIC1-mediated chloride current, which results from an increased open probability of the channel, is detected only when cAMP is elevated. Inhibition of protein kinase A prevents such current. These results indicate that CLIC1 functional expression is regulated by cAMP via protein kinase A and is required for neurite outgrowth modulation during neuronal differentiation. Using a combination of electrophysiology and immunohistochemistry, we found that the chloride intracellular channel 1 (CLIC1) protein modulates the speed of neurite growth. The chloride current mediated by CLIC1 is essential for maintaining growth cone morphology and is required for sustaining cAMP-stimulated neurite elongation in dissociated immunopurified neurons. The presence of either the CLIC1 current blocker IAA94 or the anti-CLIC1 antibody inhibits neurite growth of Retina Ganglion Cells cultured in the presence of 10 micromolar forskolin for 24 h.