Cengiz Z. Altuntas

Astrocyte-Restricted Ablation of Interleukin-17-Induced Act1-Mediated Signaling Ameliorates Autoimmune Encephalomyelitis

Interleukin-17 (IL-17) secreted by T helper 17 (Th17) cells is essential in the development of experimental autoimmune encephalomyelitis (EAE). However, it remains unclear how IL-17-mediated signaling in different cellular compartments participates in the central nervous system (CNS) inflammatory process. We examined CNS inflammation in mice with specific deletion of Act1, a critical component required for IL-17 signaling, in endothelial cells, macrophages and microglia, and neuroectoderm (neurons, astrocytes, and oligodendrocytes). In Act1-deficient mice, Th17 cells showed normal infiltration into the CNS but failed to recruit lymphocytes, neutrophils, and macrophages. Act1 deficiency in endothelial cells or in macrophages and microglia did not substantially impact the development of EAE. However, targeted Act1 deficiency in neuroectoderm-derived CNS-resident cells resulted in markedly reduced severity in EAE. Specifically, Act1-deficient astrocytes showed impaired IL-17-mediated inflammatory gene induction. Thus, astroctyes are critical in IL-17-Act1-mediated leukocyte recruitment during autoimmune-induced inflammation of the CNS.

The receptor SIGIRR suppresses Th17 cell proliferation via inhibition of the interleukin-1 receptor pathway and mTOR kinase activation

Interleukin-1 (IL-1)-mediated signaling in T cells is essential for T helper 17 (Th17) cell differentiation. We showed here that SIGIRR, a negative regulator of IL-1 receptor and Toll-like receptor signaling, was induced during Th17 cell lineage commitment and governed Th17 cell differentiation and expansion through its inhibitory effects on IL-1 signaling. The absence of SIGIRR in T cells resulted in increased Th17 cell polarization in vivo upon myelin oligodendrocyte glycoprotein (MOG(35-55)) peptide immunization. Recombinant IL-1 promoted a marked increase in the proliferation of SIGIRR-deficient T cells under an in vitro Th17 cell-polarization condition. Importantly, we detected increased IL-1-induced phosphorylation of JNK and mTOR kinase in SIGIRR-deficient Th17 cells compared to wild-type Th17 cells. IL-1-induced proliferation was abolished in mTOR-deficient Th17 cells, indicating the essential role of mTOR activation. Our results demonstrate an important mechanism by which SIGIRR controls Th17 cell expansion and effector function through the IL-1-induced mTOR signaling pathway.

IFN-γ and IL-17 Production in Experimental Autoimmune Encephalomyelitis Depends on Local APC–T Cell Complement Production

IFN-γ- and IL-17-producing T cells autoreactive across myelin components are central to the pathogenesis of multiple sclerosis. Using direct in vivo, adoptive transfer, and in vitro systems, we show in this study that the generation of these effectors in myelin oligodendrocyte glycoprotein35–55-induced experimental autoimmune encephalomyelitis depends on interactions of locally produced C3a/C5a with APC and T cell C3aR/C5aR. In the absence of the cell surface C3/C5 convertase inhibitor decay-accelerating factor (DAF), but not the combined absence of DAF and C5aR and/or C3aR on APC and T cells, a heightened local autoimmune response occurs in which myelin destruction is markedly augmented in concert with markedly more IFN-γ+ and IL-17+ T cell generation. The augmented T cell response is due to increased IL-12 and IL-23 elaboration by APCs together with increased T cell expression of the receptors for each cytokine. The results apply to initial generation of the IL-17 phenotype because naive CD62Lhigh Daf1−/− T cells produce 3-fold more IL-17 in response to TGF-β and IL-6, whereas CD62Lhigh Daf1−/−C5aR−/−C3aR−/− T cells produce 4-fold less.

β1-Adrenergic Receptor Autoantibodies Mediate Dilated Cardiomyopathy by Agonistically Inducing Cardiomyocyte Apoptosis

Background— Antibodies to the &bgr;1-adrenergic receptor (&bgr;1AR) are detected in a substantial number of patients with idiopathic dilated cardiomyopathy (DCM). The mechanism whereby these autoantibodies exert their pathogenic effect is unknown. Here, we define a causal mechanism whereby &bgr;1AR-specific autoantibodies mediate noninflammatory cardiomyocyte cell death during murine DCM. Methods and Results— We used the &bgr;1AR protein as an immunogen in SWXJ mice and generated a polyclonal battery of autoantibodies that showed selective binding to the &bgr;1AR. After transfer into naive male hosts, &bgr;1AR antibodies elicited fulminant DCM at high frequency. DCM was attenuated after immunoadsorption of &bgr;1AR IgG before transfer and by selective pharmacological antagonism of host &bgr;1AR but not &bgr;2AR. We found that &bgr;1AR autoantibodies shifted the &bgr;1AR into the agonist-coupled high-affinity state and activated the canonical cAMP-dependent protein kinase A signaling pathway in cardiomyocytes. These events led to functional alterations in intracellular calcium handling and contractile function. Sustained agonism by &bgr;1AR autoantibodies elicited caspase-3 activation, cardiomyocyte apoptosis, and DCM in vivo, and these processes were prevented by in vivo treatment with the pan-caspase inhibitor Z-VAD-FMK. Conclusions— Our data show how &bgr;1AR-specific autoantibodies elicit DCM by agonistically inducing cardiomyocyte apoptosis.

Autoimmune Targeted Disruption of the Pituitary-Ovarian Axis Causes Premature Ovarian Failure

Premature ovarian failure (POF) is characterized by amenorrhea and high serum levels of follicle-stimulating hormone (FSH). POF causes female infertility and represents a substantial women’s health risk affecting 1% of women by age 40. Although ovarian autoimmunity has been associated with POF, the identity of ovarian Ags recognized is unknown. In this study, we show that autoimmune-targeted disruption of the pituitary-ovarian axis leads to POF. Immunization of SWXJ female mice with the p215–234 peptide derived from mouse inhibin-α activates CD4+ T cells and induces experimental autoimmune oophoritis with a unique biphasic phenotype characterized by an early stage of enhanced fertility followed by a delayed stage of POF. Affected mice show high serum levels of inhibin-α-neutralizing Abs that prevent inhibin-mediated down-regulation of activin-induced pituitary FSH release. The loss of activin/FSH down-regulation leads to prolonged metestrus-diestrus, superovulation, increased numbers of mature follicles, increased offspring, accelerated depletion of primordial follicles, and ultimately premature infertility. Thus, inhibin-α-targeted experimental autoimmune oophoritis is initiated by CD4+ Th1 T cells that stimulate B cells to produce inhibin-α-neutralizing Abs directly capable of mediating POF and transferring disease into naive recipients. Our inhibin-α autoimmune model of POF shows how premature infertility may develop in the context of elevated FSH levels thereby closely mimicking the hallmark features of human POF.

Autoimmunity to Uroplakin II Causes Cystitis in Mice: A Novel Model of Interstitial Cystitis

BACKGROUNDnThe pathophysiology of interstitial cystitis (IC) is unknown. Deficits in urothelial cell layers and autoimmune mechanisms may play a role.nnnOBJECTIVEnTo examine whether immunization of mice with recombinant mouse uroplakin II (rmUPK2), a bladder-specific protein, would provoke an autoimmune response sufficient to create an IC phenotype.nnnDESIGN, SETTING, AND PARTICIPANTSnRmUPK2 complementary DNA was generated, transferred into a bacterial expression vector, and the generated protein was purified. Eight-week-old SWXJ female mice were immunized with rmUPK2 protein via subcutaneous injection of 200μg of rmUPK2 protein in 200μl of an emulsion.nnnMEASUREMENTSnMice were euthanized 5 wk after immunization. Axillary and inguinal lymph node cells were tested for antigen-specific responsiveness and cytokine production, serum isotype antibody titers against rmUPK2 were determined, and gene expression of inflammatory mediators was measured in the bladder and other organs. For functional analysis, mice were placed in urodynamic chambers for 24-h micturition frequency and total voided urine measurements.nnnRESULTS AND LIMITATIONSnImmunization with rmUPK2 resulted in T-cell infiltration of the bladder urothelium and increased rmUPK2-specific serum antibody responses in the experimental autoimmune cystitis (EAC) mice models compared with controls. The ratio of bladder to body weight was increased in EAC mice. Quantitative reverse transcriptase polymerase chain reaction analysis showed elevated gene expression of tumor necrosis factor α, interferon γ, interleukin (IL)-17A, and IL-1β in bladder urothelium but not in other organs. Evaluation of 24-h micturition habits of EAC mice showed significantly increased urinary frequency (p<0.02) and significantly decreased urine output per void (p<0.021) when compared with control mice.nnnCONCLUSIONSnOur study showed that a bladder-specific autoimmune response sufficient to induce inflammation and EAC occurs in mice following immunization with rmUPK2. EAC mice displayed significant evidence of urinary frequency and decreased urine output per void. Further phenotype characterization of EAC mice should include evidence for pain and/or afferent hypersensitivity, and evidence of urothelial cell layer damage.

Bladder dysfunction in mice with experimental autoimmune encephalomyelitis

The vast majority of patients with multiple sclerosis (MS) develop bladder control problems including urgency to urinate, urinary incontinence, frequency of urination, and retention of urine. Over 60% of MS patients show detrusor-sphincter dyssynergia, an abnormality characterized by obstruction of urinary outflow as a result of discoordinated contraction of the urethral sphincter muscle and the bladder detrusor muscle. In the current study we examined bladder function in female SWXJ mice with different defined levels of neurological impairment following induction of experimental autoimmune encephalomyelitis (EAE), an animal model of central nervous system inflammation widely used in MS research. We found that EAE mice develop profound bladder dysfunction characterized by significantly increased micturition frequencies and significantly decreased urine output per micturition. Moreover, we found that the severity of bladder abnormalities in EAE mice was directly related to the severity of clinical EAE and neurologic disability. Our study is the first to show and characterize micturition abnormalities in EAE mice thereby providing a most useful model system for understanding and treating neurogenic bladder.

Experimental Autoimmune Breast Failure: A Model for Lactation Insufficiency, Postnatal Nutritional Deprivation, and Prophylactic Breast Cancer Vaccination

Mastitis is a substantial clinical problem in lactating women that may result in severe pain and abrupt termination of breastfeeding, thereby predisposing infants to long-term health risks. Many cases of mastitis involve no known infectious agent and may fundamentally be due to autoimmune-mediated inflammation of the breast. Herein, we develop a murine model of autoimmune mastitis and provide a detailed characterization of its resulting phenotype of breast failure and lactation insufficiency. To generate breast-specific autoimmunity, we immunized SWXJ mice with recombinant mouse α-lactalbumin, a lactation-dependent, breast-specific differentiation protein critical for production of lactose. Mice immunized with α-lactalbumin showed extensive T-cell-mediated inflammation in lactating normal breast parenchyma but none in nonlactating normal breast parenchyma. This targeted autoimmune attack resulted in breast failure characterized by lactation insufficiency and decreased ability to nurture offspring. Although immunization with α-lactalbumin had no effect on fertility and birth numbers, pups nursed by α-lactalbumin-immunized mice showed significantly disrupted growth often accompanied by kwashiorkor-like nutritional abnormalities, including alopecia, liver toxicity, and runting. This experimental model of autoimmune breast failure has useful applications for prophylactic breast cancer vaccination and for addressing inflammatory complications during breastfeeding. In addition, this model is suited for investigating nutritionally based failure-to-thrive issues, particularly regarding the long-term implications of postnatal nutritional deprivation.

Autoimmune Mediated Regulation of Ovarian Tumor Growth

OBJECTIVESnAn immune response sufficient to induce organ failure may provide protection and therapy against tumors derived from the targeted organ particularly when removal or ablation of the organ is part of the standard therapy and does not threaten survival. We have previously shown that a targeted immune response directed against the ovarian-specific protein, inhibin-α, causes ovarian failure. Here we determined whether inhibin-α autoimmunity is effective in both prevention and treatment of ovarian tumors.nnnMETHODSnA transgene consisting of the SV40 large tumor transformation antigen under the regulation of an anti-Mullerian hormone promoter (AMH-SV40Tag) was transferred by backcrossing for 12 generations to SJL/J mice producing SJL.AMH-SV40Tag (H-2(s)) females that develop a high incidence of autochthonous granulosa cell tumors. We determined whether immunization of SJL.AMH-SV40Tag female mice with the IA(s)-restricted p215-234 peptide of mouse inhibin-α was capable of preventing and treating these ovarian tumors.nnnRESULTSnThe growth of autochthonous ovarian granulosa cell tumors in SJL.AMH-SV40Tag transgenic mice was significantly inhibited in mice immunized with Inα 215-234. In addition, significant inhibition of tumor growth occurred when mice with established ovarian granulosa cell tumors were therapeutically vaccinated with Inα 215-234.nnnCONCLUSIONSnOur results indicate that induction of ovarian-specific autoimmunity may serve as an effective way to prevent the emergence of autochthonous ovarian tumors and control the growth of established ovarian malignancies.

Disruption of estrous cycle homeostasis in mice with experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is widely viewed as a prototypic human autoimmune disease involving proinflammatory T cells that induce lesions in the central nervous system (CNS) in response to myelin self proteins. Although the impact of sex hormones on MS is well recognized, the converse effects of autoimmunity on sex hormones are still unclear. The current study was designed to assess the impact of CNS autoimmunity on female reproductive physiology. In order to identify subtle hormonal disturbances as a result of autoimmunity, we analyzed the estrous cycle in SJL/J mice after active induction of experimental autoimmune encephalomyelitis (EAE), an animal model with substantial similarities to MS. Here we show that CNS autoimmunity significantly shortens the murine estrous cycle. This shortening of the estrous cycle is characterized by a dramatic decrease in the length of the metestrus-diestrus luteal phase partially offset by a highly significant but less dramatic elongation of the proestrus-estrus follicular phase of the uterine cycle. Thus, our study provides experimental evidence for a direct causal link between CNS autoimmunity and disruption of the homeostatic balance of the uterine cycle often observed in women with MS.