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Background Type-17 inflammation characterizes psoriasis, a chronic skin disease. Because several inflammatory cytokines contribute to psoriasis pathogenesis, inhibiting the simultaneous production of these cytokines in TH17 cells may be beneficial in psoriasis. We found that Cav1.4, encoded by CACNA1F, was the only Cav1 calcium channel expressed in TH17 cells. Objective We sought to investigate the role of Cav1.4 expression in early TH17-activation events and effector functions, as well as its association with TH17 signature genes in lesional psoriatic (LP) skins. Methods Transcriptional gene signatures associated with CACNA1F expression were examined in LP skins by RT-PCR and in situ hybridization. Cav1 inhibitor and/or shRNA lentivectors were used to assess the contribution of Cav1.4 in TH17 activation and effector functions in a 3-dimensional skin reconstruction model. Results CACNA1F expression correlated with inflammatory cytokine expression that characterizes LP skins and was preferentially associated with RORC expression in CD4+ and CD4− cells from LP biopsies. Nicardipine, a Cav1 channel antagonist, markedly reduced inflammatory cytokine production by TH17 cells from blood or LP skin. This was associated with decreased TCR-induced early calcium events at cell membrane and proximal signaling events. The knockdown of Cav1.4 in TH17 cells impaired cytokine production. Finally, Cav1 inhibition reduced the expression of the keratinocyte genes characteristic of TH17-mediated psoriasis inflammation in human skin equivalents. Conclusions Cav1.4 channels promote TH17-cell functions both at the periphery and in inflammatory psoriatic skin.

Calcium is a second messenger essential, in all cells, for most cell functions. The spatio-temporal control of changes in intracellular calcium concentration is partly due to the activation of calcium channels. Voltage-operated calcium channels are present in excitable and non-excitable cells. If the mechanism of voltage-operated calcium channels is well known in excitable cells the Ca

At the onset of adolescence, asthma becomes less prevalent in males than in females, suggesting a protective role of male sex hormones. Here, Laffont et al. show that androgens negatively control ILC2 development and ILC2-driven lung inflammation in male mice., Prevalence of asthma is higher in women than in men, but the mechanisms underlying this sex bias are unknown. Group 2 innate lymphoid cells (ILC2s) are key regulators of type 2 inflammatory responses. Here, we show that ILC2 development is greatly influenced by male sex hormones. Male mice have reduced numbers of ILC2 progenitors (ILC2Ps) and mature ILC2s in peripheral tissues compared with females. In consequence, males exhibit reduced susceptibility to allergic airway inflammation in response to environmental allergens and less severe IL-33–driven lung inflammation, correlating with an impaired expansion of lung ILC2s. Importantly, orchiectomy, but not ovariectomy, abolishes the sex differences in ILC2 development and restores IL-33–mediated lung inflammation. ILC2Ps express the androgen receptor (AR), and AR signaling inhibits their differentiation into mature ILC2s. Finally, we show that hematopoietic AR expression limits IL-33–driven lung inflammation through a cell-intrinsic inhibition of ILC2 expansion. Thus, androgens play a crucial protective role in type 2 airway inflammation by negatively regulating ILC2 homeostasis, thereby limiting their capacity to expand locally in response to IL-33.

Resume L’asthme est une pathologie touchant plus de 4 millions de personnes en France. Le role des lymphocytes Th2 (LTh2) produisant de l’interleukine (IL)-4, de l’IL-5 et de l’IL-13 dans la physiopathologie de l’asthme allergique n’est plus a prouver. Les differentes populations de LT expriment des equipements distincts en composants regulant la [Ca2+]i. La comprehension de la signalisation calcique propre a chaque population de LT permettrait de concevoir des approches therapeutiques specifiques utiles pour le traitement des differentes maladies dans lesquelles elles sont impliquees, telles que l’asthme allergique pour les LTh2, sans engendrer d’immunosuppression globale. Notre equipe a demontre le role essentiel des canaux calciques Cav1.2 et Cav1.3 et de leurs sous-unites auxiliaires dans la fonction des LTh2 humains et murins et le developpement de l’asthme allergique chez la souris. Nous discuterons des potentialites therapeutiques qu’apporte l’identification d’une voie de signalisation calcique propre aux LTh2. Nous proposerons de cibler selectivement cette reponse calcique Th2 pour court-circuiter la reponse inflammatoire chronique caracteristique des maladies allergiques en evitant une immunosuppression globale puisque ces canaux sont exprimes selectivement dans les LTh2.

Calcium is a second messenger essential, in all cells, for most cell functions. The spatio-temporal control of changes in intracellular calcium concentration is partly due to the activation of calcium channels. Voltage-operated calcium channels are present in excitable and non-excitable cells. If the mechanism of voltage-operated calcium channels is well known in excitable cells the Ca2+ toolkit used in non-excitable cells to activate the calcium channels is less described. Herein we discuss about very similar pathways involving voltage activated Cav1 channels in two unrelated non-excitable cells; ectoderm cells undergoing neural development and effector Th2 lymphocytes responsible for parasite elimination and also allergic diseases. We will examine the way by which these channels operate and are regulated, as well as the consequences in terms of gene transcription. Finally, we will consider the questions that remain unsolved and how they might be a challenge for the future.

International audience; BACKGROUND: T-lymphocytes express not only the cell membrane calcium ORAI1 but also voltage-dependent Cav1 channels. In excitable cells, these channels are composed of the ion forming pore α1 and auxiliary subunits (β and α2δ) needed for proper trafficking and activation of the channel. We previously disclosed the role of Cav1.2 α1 in mouse and human Th2- but not Th1-cell functions and showed that knocking-down Cav1 α1 prevents experimental asthma OBJECTIVE: We investigated the role of β and α2δ auxiliary subunits on Cav1 α1 function in Th2 lymphocytes and on the development of acute allergic airway inflammation. METHODS: We used antisense oligonucleotides (CavβAS) to knockdown Cavβ and gabapentin, a drug that binds to and inhibits α2δ1 and α2δ2, to test their effects on Th2 functions and their capacity to reduce allergic airway inflammation. RESULTS: Mouse and human Th2-cells express mainly Cavβ1, β3 and α2δ2 subunits. CavβAS reduces TCR-driven calcium responses and cytokine production by mouse and human Th2, with no effect on Th1-cells. Cavβ is mainly involved in restraining Cav1.2 α1 degradation through the proteasome as a proteasome inhibitor partially restores the α1 protein level. Gabapentin impairs TCR-driven calcium response and cytokine production associated with the loss of α2δ2 protein in Th2-cells. CONCLUSIONS: These results stress the role of Cavβ and α2δ2 auxiliary subunits in the stability and activation of Cav1.2 channels in Th2 lymphocytes both in vitro and in vivo as demonstrated by the beneficial effect of CavβAS and gabapentin in allergic airway inflammation. CLINICAL IMPLICATIONS: The demonstration that auxiliary subunits are involved in calcium signaling through Cav1 channels and function of mouse and human Th2-lymphocytes supports their potential beneficial effect on allergic asthma.

Calcium signaling is essential for all the functions of T lymphocytes, including those of Th2 cells. Th2 lymphocytes producing interleukins 4, 5 and 13 orchestrate allergic diseases including asthma. T-cell activation induces an influx of Ca(2+) from the external medium through ORAI calcium channels although other calcium channels are likely to be involved. Among them, voltage-gated calcium (Ca(v)1) channels have been reported in some T-cell subsets including Th2 cells. The inhibition of Ca(v)1 channels abrogates T-cell receptor-driven calcium influx and interleukin production by Th2 cells. From a therapeutic point of view, the inhibition of Ca(v)1 channels prevents Th2-dependent experimental allergic asthma. In this review, we will discuss the singularities of calcium responses depending upon the T-cell subset and its state of activation.

Brown Norway rats injected with aurothiopro-panolsulfonate sodium salt develop systemic autoimmunity. The aim of this study was to assess the influence of the sulfur-containing group in this experimental model of gold-induced autoimmunity. It was shown that the sulfur-containing group does not induce autoimmunity of itself, but potentiates the immunotoxic effects of gold.

Th2 cells orchestrate allergic asthma and the cytokines they produce (IL-4, IL-5, and IL-13) are deleterious in allergy. Therefore, it is important to identify key signaling molecules expressed by Th2 cells that are essential for their function. We have previously shown that dihydropyridines selectively modulate Th2 cell functions.Because dihydropyridines bind to and modulate voltage-dependent calcium (Ca(v)1) channel in excitable cells, we aimed at showing that Th2 cells selectively express functional Ca(v)1-related channels, the inhibition of which may prevent asthma.We looked for Ca(v)1 channel expression in Th2 and Th1 cells by real-time polymerase chain reaction and Western blotting. We sequenced the isoforms expressed by Th2 cells and tested whether Ca(v)1 antisense oligodeoxynucleotides (Ca(v)1AS) affected Ca(2+) signaling and cytokine production. Finally, we tested the effect of Ca(v)1AS in the passive asthma model by injection of ovalbumin-specific Th2 cells transfected with Ca(v)1AS into BALB/c mice challenged with intranasal ovalbumin and in the active model of asthma by intranasal delivery of Ca(v)1AS together with soluble ovalbumin in BALB/c mice previously immunized with ovalbumin in alum.We show that mouse Th2 but not Th1 cells expressed Ca(v)1.2 and Ca(v)1.3 channels. Th2 cells transfected with Ca(v)1AS had impaired Ca(2+) signaling and cytokine production, and lost their ability to induce airway inflammation on adoptive transfer. Furthermore, intranasal administration of Ca(v)1AS suppressed airway inflammation and hyperreactivity in an active model of asthma.These results indicate that Th2 cells selectively express Ca(v)1 channels that may be efficiently targeted in T lymphocytes to prevent experimental asthma.

Th2 lymphocytes differ from other CD4+ T lymphocytes not only by their effector tasks but also by their T cell receptor (TCR)-dependent signaling pathways. We previously showed that dihydropyridine receptors (DHPR) involved in TCR-induced calcium inflow were selectively expressed in Th2 cells. In this report, we studied whether cGMP-dependent protein kinase G (PKG) activation was implicated in the regulation of DHPR-dependent calcium response and cytokine production in Th2 lymphocytes. The contribution of cGMP in Th2 signaling was supported by the following results: 1) TCR activation elicited cGMP production, which triggered calcium increase responsible for nuclear factor of activated T cell translocation and Il4 gene expression; 2) guanylate cyclase activation by nitric oxide donors increased intracellular cGMP concentration and induced calcium inflow and IL-4 production; 3) reciprocally, guanylate cyclase inhibition reduced calcium response and Th2 cytokine production associated with TCR activation. In addition, DHPR blockade abolished cGMP-induced [Ca2+]i increase, indicating that TCR-induced DHP-sensitive calcium inflow is dependent on cGMP in Th2 cells. Th2 lymphocytes from PKG1-deficient mice displayed impaired calcium signaling and IL-4 production, as did wild-type Th2 cells treated with PKG inhibitors. Altogether, our data indicate that, in Th2 cells, cGMP is produced upon TCR engagement and activates PKG, which controls DHP-sensitive calcium inflow and Th2 cytokine production.

It is clear that functional heterogeneity of T cells may be explained by differential cytokine production. The aim of this paper was to review evidence for regulatory cells, generated after HgCl(2)-exposure. They differ from classical Th1 and Th2 cells, produce transforming growth factor-beta and interleukin-10 and exert their regulatory functions in a Th1/Th2-unrestricted fashion.

Th1 and Th2 cells produce different cytokines and have distinct functions. Th1/Th2 cell differentiation is influenced, among other factors, by the nature of TCR-MHC interactions. However, how the TCR transduces a signal resulting in IFN-gamma or IL-4 production is a matter of debate. For example, some authors reported a loss of calcium signaling pathway in Th2 cells. We used a T cell hybridoma producing IL-4 upon weak TCR stimulation and both IL-4 and IFN-gamma for strong TCR engagement as a model to study how TCR signaling pathways are differentially activated in both conditions of stimulation and how this influences the production of cytokines. We show that: (1) the calcium response is identical following weak and strong TCR stimulation; (2) mitogen-activated protein kinase(MAPK) activation is a gradual phenomenon depending upon the strength of TCR activation; (3) a calcium response, even weak, triggers IL-4 expression; (4) IFN-gamma synthesis requires not only a calcium response but also MAPK activation. The MAPK pathway is dispensable for IL-4 production, although it amplifies IL-4 synthesis upon strong TCR stimulation; (5) TCR-induced IL-4 production also depends on calcium signaling in Th2 cells, while IFN-gamma synthesis is dependent, in addition, on MAPK activation in Th1 cells.

> La reconnaissance du peptide antigenique par son recepteur (TCR) entraine une augmentation de la concentration de Ca2+ dans le cytosol ([Ca2+]i), necessaire a la differenciation et aux fonctions effectrices des lymphocytes (L)T. La stimulation via le TCR permet le recrutement de molecules adaptatrices et le couplage a des enzymes, dont la phospholipase Cγ, qui produit de l’inositol 1,4,5 tri-phosphate (IP3) et du diacylglycerol. L’IP3 en se fixant a ses recepteurs du reticulum endoplasmique libere les stocks de Ca2+ dans le cytosol (Figure 1). L’entree de Ca2+ a partir du milieu extracellulaire reconstitue ces stocks et maintient une signalisation soutenue. Les canaux calciques responsables sont definis comme des SOC (store-operated Ca2+ channels) mais leur identite moleculaire n’est pas completement elucidee. Un des principaux facteurs de transcription active par la voie calcique est NFAT (nuclear factor of activated T cells). La calcineurine, une phosphatase regulee par le Ca2+ dephosphoryle NFAT, ce qui permet sa localisation nucleaire et l’expression des genes cibles.

Mercuric chloride (HgCl2) induces T helper 2 (Th2) autoreactive anti-class II T cells in Brown Norway rats. These cells produce interleukin (IL)-4 and induce a B cell polyclonal activation that is responsible for autoimmune disease. In Brown Norway rats, HgCl2 triggers early IL-4 mRNA expression both in vivo and in vitro by T cells, which may explain why autoreactive anti-class II T cells acquire a Th2 phenotype. The aim of this study was to explore the transduction pathways by which this chemical operates. By using two murine T cell hybridomas that express IL-4 mRNA upon stimulation with HgCl2, we demonstrate that: 1) HgCl2 acts at the transcriptional level without requiring de novo protein synthesis; 2) HgCl2 induces a protein kinase C-dependent Ca2+ influx through L-type calcium channels; 3) calcium/calcineurin-dependent pathway and protein kinase C activation are both implicated in HgCl2-induced IL-4 gene expression; and 4) HgCl2 can activate directly protein kinase C, which might be one of the main intracellular target for HgCl2. These data are in agreement with an effect of HgCl2 which is independent of antigen-specific recognition. It may explain the T cell polyclonal activation in the mercury model and the expansion of pathogenic autoreactive anti-class II Th2 cells in this context.

Autoreactive anti–MHC class II T cells are found in Brown Norway (BN) and Lewis (LEW) rats that receive either HgCl2 or gold salts. These T cells have a T helper cell 2 (Th2) phenotype in the former strain and are responsible for Th2-mediated autoimmunity. In contrast, T cells that expand in LEW rats produce IL-2 and prevent experimental autoimmune encephalomyelitis, a cell-mediated autoimmune disease. The aim of this work was to investigate, using T cell lines derived from HgCl2-injected LEW rats (LEWHg), the effect of these autoreactive T cells on the development of Th2-mediated autoimmunity. The five LEWHg T cell lines obtained protect against Th2-mediated autoimmunity induced by HgCl2 in (LEW × BN)F1 hybrids. The lines produce, in addition to IL-2, IFN-γ and TGF-β, and the protective effect is TGF-β dependent since protection is abrogated by anti-TGF-β treatment. These results identify regulatory, TGF-β–producing, autoreactive T cells that are distinct from classical Th1 or Th2 and inhibit both Th1- and Th2-mediated autoimmune diseases.

The role of voltage-dependent calcium (Cav1) channels is prominent in excitable cells while store-operated calcium channels (SOCC) were considered as characteristic of non-excitable cells. Cav1 channels are implicated in excitation transcription. Store-operated calcium channels (SOCC) activity is increased during cardiac stress and would contribute to Ca2+ influx and expression of genes responsible for cardiac hypertrophy and heart failure (Luo et al., 2012). Several lines of evidence now show the importance of Cav1 channels in non-excitable cells including lymphocytes (reviewed in Robert et al., 2011, 2013). Cav1 channels are defined by their voltage sensitivity and their sensitivity to drugs as dihydropyridines, phenylalkylamines, benzothiazepines, known to alter T-cell functions. However the drug concentrations needed were higher compared to excitable cells. The absence of cell membrane depolarization upon activation and possible non-specific effects of the drugs questioned the putative role of Cav1 channels in T-cells. Cav1 channels are formed by the ion forming pore α1 subunit encoded by four genes conferring some tissue-specific expression pattern in excitable cells. Cav1.1 is characteristic of skeletal muscle cells. Cav1.2 is found in neurons, heart, and smooth muscle cells while Cav1.3 is detected in neuroendocrine cells. Cav1.2 and Cav1.3 can be found in the same tissues even if their role is not redundant as shown by the differential phenotypes of Cav1.2 and Cav1.3 null mice. Cav1.4 is the retinal form. Cav1 channel isoforms differ by their sensitivity to depolarization and to antagonizing drugs such as dihydropyridines (DHP) as well as by their inactivation properties (Lipscombe et al., 2004). For example, Cav1.4 channels activate at more negative potentials than Cav1.3 and Cav1.2, which highlights the potential involvement of Cav1.4 in non-excitable cells as mast cells (McRory et al., 2004) and more recently in mouse T-lymphocytes (Omilusik et al., 2011).

CD4+ helper T (Th) lymphocytes orchestrate the immune response and include several types of effectors such as Th1, Th17 and Th2 cells. They fight against intracellular, extracellular pathogens and parasites respectively. They may also cause distinct immunopathological disorders. Th1 and Th17 are implicated in the development of autoimmune diseases while Th2 cells can initiate allergic diseases. These subsets differ by their TCR-associated signaling. In addition, the regulation of intracellular calcium concentration is not the same in Th1, Th2 and 17 cells. Our group showed that Th2 cells selectively overexpressed voltage-activated calcium (Cav1)-related channels. An increasing number of groups report the presence of Cav1-related products in T-lymphocyte subsets. This is a matter of debate since these calcium channels are classically defined as activated by high cell membrane depolarization in excitable cells. However, the use of mice with ablation of some Cav1 subunits shows undoubtedly an immune phenotype raising the question of how Cav1 channels are regulated in lymphocytes. We showed that knocking down Cav1.2 and/or Cav1.3 subunits impairs the functions of Th2 lymphocytes and is beneficial in experimental models of asthma, while it has no effect on Th1 cell functions. Beyond the role of Cav1 channels in T-lymphocytes, the identification of key components selectively implicated in one or the other T cell subset paves the way for the design of new selective therapeutic targets in the treatment of immune disorders while preserving the other T-cell subsets. This article is part of a Special Issue entitled: 12th European Symposium on Calcium.

Calcium signaling is essential for all the functions of T lymphocytes, including those of Th2 cells. Th2 lymphocytes producing interleukins 4, 5 and 13 orchestrate allergic diseases including asthma. T-cell activation induces an influx of Ca(2+) from the external medium through ORAI calcium channels although other calcium channels are likely to be involved. Among them, voltage-gated calcium (Ca(v)1) channels have been reported in some T-cell subsets including Th2 cells. The inhibition of Ca(v)1 channels abrogates T-cell receptor-driven calcium influx and interleukin production by Th2 cells. From a therapeutic point of view, the inhibition of Ca(v)1 channels prevents Th2-dependent experimental allergic asthma. In this review, we will discuss the singularities of calcium responses depending upon the T-cell subset and its state of activation.

Brown-Norway (BN) rats injected with HgCl2 develop a systemic autoimmune disease associated with a polyclonal B cell activation, due to autoreactive T cells specific for self-class II molecules, while Lewis (LEW) rats injected with HgCl2 do not exhibit autoimmunity and develop a non-antigen-specific, CD8-mediated immunosuppression assessed by a depression of T cell functions, and a protection against experimental autoimmune encephalomyelitis (EAE). Resistance to HgCl2-induced autoimmunity is not due to these suppressor cells since treatment with an anti-CD8 monoclonal antibody (mAb) did not allow autoimmunity to appear. The absence of autoimmunity in this strain could result from the absence of autoreactive T cells, or from quantitative or qualitative differences of these cells between susceptible and resistant strains. In the present study, we show that CD4+ anti-class II T cells are present in HgCl2-injected LEW rats and are as frequent as in BN rats when assessed by limiting dilution analysis. LEW CD4+ autoreactive T cell lines were derived. They proliferated in the presence of normal class II-bearing cells, secreted interleukin 2, and did not induce B cells to produce immunoglobulins. Transfer of one of these lines, LEW Hg A, into normal LEW rats led to the appearance of CD8+ cells responsible for a non-antigen-specific immunosuppression that induced complete protection from EAE. Immunosuppression was abrogated after treatment with an anti-CD8 mAb. In vitro, CD8+ cells from rats injected with the LEW Hg A T cell line proliferated in the presence of activated T cells whatever their origin. We conclude that HgCl2 induces CD4+ autoreactive T cells that proliferate in the presence of class II+ cells in susceptible BN as well as in resistant LEW rats. But while these cells collaborate with B cells to produce autoantibodies in BN rats, they initiate in LEW rats a suppressor circuit involving antiergotypic CD8+ suppressor cells.

SUMMARY Gold salts, d-penicillamine or mercurials induce autoimmunity in Brown Norway (BN) rats and provoke an immunosuppression in Lewis (LEW) rats. It has been suggested that immunologically mediated manifestations induced by drugs could result from graft-verves-host (GVH) like reactions. We show that BN spleen cells transferred into (LEW × BN)FI hybrids induce a chronic GVH reaction (GVHR). This reaction led to an autoimmune disease quite similar to that induced by drugs in BN rats. In both situations, a common part of the B cell repertoire is triggered. In contrast. LEW spleen cells transferred into (LEW × BN)FI hybrids provoke a lethal GVHR. This is to be compared with the CD8-mediated immunosuppression observed in LEW rats injected with HgCI2. These findings are in agreement with the prediction that immune dysregulation induced by drugs leads to GVH-like reactions either stimulatory or suppressive depending upon the strain tested.

RATIONALE: Ca(2+) signaling controls the production of T helper (Th) type 2 cytokines known to be deleterious in asthma. Recently, we showed that Ca(2+) signaling was dihydropyridine (DHP)-sensitive in Th2 lymphocytes and that the DHP derivate, nicardipine, used in the treatment of cardiovascular pathologies, prevents Th2-dependent B cell polyclonal activation. OBJECTIVES: We tested the effect of nicardipine in experimental allergic asthma. METHODS: BALB/c mice immunized with ovalbumin (OVA) in alum and challenged with intranasal OVA were treated with nicardipine once the Th2 response, or even airway inflammation, was induced. We also tested the effect of nicardipine in asthma induced by transferring OVA-specific Th2 cells in BALB/c mice exposed to intranasal OVA. We checked the impact of nicardipine on T-cell responses and airway inflammation. MEASUREMENTS AND MAIN RESULTS: Nicardipine inhibited in vitro Ca(2+) response in Th2 cells. In vivo, it impeded the development of Th2-mediated airway inflammation and reduced the capacity of lymphocytes from lung-draining lymph nodes to secrete Th2, but not Th1, cytokines. Nicardipine did not affect antigen presentation to CD4(+) T lymphocytes, nor the initial localization of Th2 cells into the lungs of mice exposed to intranasal OVA; however, it reduced the production of type 2 cytokines and the amplification of the Th2 response in mice with asthma. Conversely, nicardipine had no effect on Th1-mediated airway inflammation. CONCLUSIONS: Nicardipine improves experimental asthma by impairing Th2-dependent inflammation. This study could provide a rationale for developing drugs selectively targeting DHP receptors of Th2 lymphocytes, potentially beneficial in the treatment of asthma.

Brown Norway (BN) rats treated with aurothiopropanol-sulfonate (Atps) constitute a model of Th2-mediated immunological disorders associated with elevated IgE responses and renal IgG deposits. Using F2 offspring between Atps-susceptible BN and Atps-resistant Lewis rats, we had previously mapped three quantitative trait loci on chromosomes 9, 10, and 20 for which BN alleles increased susceptibility to Atps-induced immunological disorders (Aiid). In this study we have used congenic lines for the latter two quantitative trait loci, formerly called Atps2 and Atps3 and now named Aiid2 (chromosome 10) and Aiid3 (chromosome 9), for fine mapping and characterization of their impact on Atps-triggered reactions. In Aiid2 congenic lines, the gene(s) controlling part of the IgE response to Atps was mapped to an ∼7-cM region, which includes the IL-4 cytokine gene cluster. Two congenic lines in which the introgressed segments shared only a portion of this 7-cM region, showed an intermediate IgE response, indicating the involvement of several genes within this region. Results from BN rats congenic for the Lewis Aiid3 locus, which we mapped to a 1.2-cM interval, showed a stronger effect of this region. In this congenic line, the Atps-triggered IgE response was 10-fold lower than in the BN parental strain, and glomerular IgG deposits were either absent or dramatically reduced. Further genetic and functional dissections of these loci should provide insights into pathways that lead to Th2-adverse reactions.

Th1 cells that produce IFN-γ are essential in the elimination of intracellular pathogens, and Th2 cells that synthetize IL-4 control the eradication of helminths. However, highly polarized Th1 or Th2 responses may be harmful and even lethal. Thus, the development of strategies to selectively down-modulate Th1 or Th2 responses is of therapeutic importance. Herein, we demonstrate that dihydropyridine receptors (DHPR) are expressed on Th2 and not on Th1 murine cells. By using selective agonists and antagonists of DHPR, we show that DHPR are involved in TCR-dependent calcium response in Th2 cells as well as in IL-4, IL-5, and IL-10 synthesis. Nicardipine, an inhibitor of DHPR, is beneficial in experimental models of Th2-dependent pathologies in rats. It strongly inhibits the Th2-mediated autoimmune glomerulonephritis induced by injecting Brown Norway (BN) rats with heavy metals. This drug also prevents the chronic graft vs host reaction induced by injecting CD4+ T cells from BN rats into (LEW × BN)F1 hybrids. By contrast, treatment with nicardipine has no effect on the Th1-dependent experimental autoimmune encephalomyelitis triggered in LEW rats immunized with myelin. These data indicate that 1) DHPR are a selective marker of Th2 cells, 2) these calcium channels contribute to calcium signaling in Th2 cells, and 3) blockers of these channels are beneficial in the treatment of Th2-mediated pathologies.

de la meme facon gardent leur capacite a induire une pathologie respiratoire. On peut imaginer que la dihydropyridine antagoniste pourrait agir via les canaux Kv1.3. Cependant, le resultat avec la DHP agoniste ne peut s’expliquer par une interaction avec ce type de canal et une induction d’un signal calcium. Les resultats avec les oligonucleotides antisens (Cav1.2 et Cav1.3), comme le souligne Alain Trautmann, montrent que Cav1.2 et Cav1.3 agissent au moins en tant que modulateurs de la reponse calcique. L’entree du calcium est modulee via differentes familles de canaux calciques repondant a differents stimulus (depolarisation, mediateurs chimiques et peptidiques, messagers intracellulaires, depletion des stocks calciques internes). Ces canaux sont inclus dans des complexes macromoleculaires constitues de plusieurs proteines. C’est le complexe supramoleculaire qui est porteur de la fonction et non un seul des elements du complexe. On peut aisement imaginer que la cellule utilise les differentes proteines mises a sa disposition dans la « boite a outil » du signal calcium (le calcium toolkit de M. Berridge) pour creer des complexes capables de realiser une fonction particuliere dans un environnement cellulaire defini. Dans cet assemblage supramoleculaire, ou passe l’ion calcium et quelle est l’entite qui joue physiquement le role de canal sont effectivement des questions ouvertes. Si la sous-unite alpha n’est pas physiquement le canal, cela signifie qu’une meme proteine pourrait avoir des roles differents selon le contexte. Cela a deja ete decrit dans les cellules procaryotes, mais ce serait une information de premiere importance dans les cellules eucaryotes. Ainsi, selon le complexe moleculaire dans lequel ils sont impliques, les canaux calciques Cav1 dependants du voltage ne seraient plus ni dependants du voltage, ni eventuellement canaux. L’aphorisme pionnier de Francois Jacob « la nature bricole » serait ici parfaitement illustre. Alain Trautmann souleve plusieurs questions importantes dans sa reponse a notre article sur le role des canaux dependants du voltage dans la regulation du signal calcium dans la sous-population Th2 des lymphocytes T (➜) [1, 2]. Sauf a considerer qu’il existe un biais experimental dans les donnees, l’ensemble des resultats indique un role de Cav1.2 et Cav1.3 dans la regulation du signal calcium dans la population de lymphocytes Th2 qui serait absent dans la population Th1. Pour memoire, rappelons que : • dans les lymphocytes Th2, la reponse calcique, la transcription des genes de cytokines et la production de cytokines sont inhibees par une dihydropyridine (DHP) antagoniste des canaux Cav1, et ce de maniere dependante de la dose. Il n’y a pas d’effet sur la reponse calcique dependante de la thapsigargine ou de l’ionomycine ; • une DHP agoniste induit un influx de calcium et l’expression des genes de cytokines dans les Th2 et pas dans les Th1 ; • la transfection des Th2 avec des oligonucleotides antisens specifiques de Cav1.2 ou Cav1.3 reduit de moitie l’expression du canal cible sans effet sur d’autres molecules importantes dans l’homeostasie du calcium intracellulaire. La transfection avec ces antisens inhibe fortement l’augmentation de [Ca2+]i qui survient en reponse a l’activation du TCR et la production de cytokines par les Th2. Ces antisens ne modifient pas la reponse a l’ionomycine ou a la thapsigargine. Il n’y a pas d’effet sur les Th1 ; • les Th2 (une population impliquee dans le developpement de l’asthme allergique) transfectes avec les oligonucleotides Cav1AS perdent leur capacite a induire un asthme quand ils sont transferes chez un hote expose a l’antigene par voie aerienne, alors que les Th1 traites (➜) Voir dans ce numero l’artcile de V. Robert et al., page 773 et la reponse d’A. Trautmann page 781

Down modulation of Heymann's nephritis by mercuric chloride. The time course of Heymann's nephritis (HN), assessed on proteinuria and immunomorphology, has been compared in Lewis (LEW) rats immunized with BB alone (group A) or injected with HgCl 2 and subsequently immunized in a similar manner (group B). Whereas all rats from group A developed typical HN characterized by heavy proteinuria and abundant glomerular immune deposits, rats from group B did not develop or developed a markedly attenuated form of HN; proteinuria was never detectable, immune deposits were absent or minimal. No abnormalities were found in rats injected with HgCl 2 alone. In order to explain our findings, we have studied the glomerular and tubular expression of the 330 kD nephritogeriic glycoprotein (gp330) as well as the corresponding antibody response. In rats receiving HgCl 2 , gp330 was normally expressed on BB and glomerular epithelial cells as indicated by in vitro and in vivo binding of anti-gp330 antibodies, but titers of anti-BB and anti-gp330 antibodies were considerably lower than in group A control rats. These findings therefore suggest that HgCl 2 acts by its immunodepressive effect recently related to an increase in T suppressor cells. This effect is paradoxical since HgCl 2 induces autoimmunity in Brown-Norway rats, and we suggest that it may be akin to observations reported in clinical practice where drugs may be immunostimulatory in some patients and immunodepressive in others. The mercury model may therefore represent a unique tool to evaluate the relationship between genetics and drug-induced immune dysregulation.