Tissue-type plasminogen activator (tPA) is a highly specific serine proteinase expressed in the CNS during events that require neuronal plasticity. In this study we demonstrate that endogenous tPA mediates the progression of kainic acid–induced (KA-induced) seizures by promoting the synchronization of neuronal activity required for seizure spreading, and that, unlike KA-induced cell death, this activity is plasminogen-independent. Specifically, seizure induction by KA injection into the amygdala induces tPA activity and cell death in both hippocampi, and unilateral treatment of rats with neuroserpin, a natural inhibitor of tPA in the brain, enhances neuronal survival in both hippocampi. Inhibition of tPA within the hippocampus by neuroserpin treatment does not prevent seizure onset but instead markedly delays the progression of seizure activity in both rats and wild-type mice. In tPA-deficient mice, seizure progression is significantly delayed, and neuroserpin treatment does not further delay seizure spreading. In contrast, plasminogen-deficient mice show a pattern of seizure spreading and a response to neuroserpin that is similar to that of wild-type animals. These findings indicate that tPA acts on a substrate other than plasminogen and that the effects of neuroserpin on seizure progression and neuronal cell survival are mediated through the inhibition of tPA.
Manuel Yepes, Maria Sandkvist, Timothy A. Coleman, Elizabeth Moore, Jiang-Young Wu, David Mitola, Thomas H. Bugge, Daniel A. Lawrence
We recently showed that human skin fibroblasts internalize fluorescent analogues of the glycosphingolipids lactosylceramide and globoside almost exclusively by a clathrin-independent mechanism involving caveolae. In contrast, a sphingomyelin analogue is internalized approximately equally via clathrin-dependent and caveolar routes. Here, we further characterized the caveolar pathway for glycosphingolipids, showing that Golgi targeting of sphingolipids internalized via caveolae required microtubules and phosphoinositol 3-kinases and was inhibited in cells expressing dominant-negative Rab7 and Rab9 constructs. In addition, overexpression of wild-type Rab7 or Rab9 (but not Rab11) in Niemann-Pick type C (NP-C) lipid storage disease fibroblasts resulted in correction of lipid trafficking defects, including restoration of Golgi targeting of fluorescent lactosylceramide and endogenous GM1 ganglioside, and a dramatic reduction in intracellular cholesterol stores. Our results demonstrate a role for Rab7 and Rab9 in the Golgi targeting of glycosphingolipids and suggest a new therapeutic approach for restoring normal lipid trafficking in NP-C cells.
Amit Choudhury, Michel Dominguez, Vishwajeet Puri, Deepak K. Sharma, Keishi Narita, Christine L. Wheatley, David L. Marks, Richard E. Pagano
NF-κB essential modifier (NEMO), also known as IKK-γ, is a member of the I-κB kinase complex responsible for phosphorylating I-κB, allowing the release and activation of NF-κB. Boys with an expressed NEMO mutation have an X-linked syndrome characterized by hypohidrotic ectodermal dysplasia with immune deficiency (HED-ID). The immunophenotype resulting from NEMO mutation is highly variable, with deficits in both T and B cell responses. We evaluated three patients with NEMO mutations (L153R, Q403X, and C417R) and HED-ID who had evidence of defective CD40 signaling. All three patients had normal percentages of peripheral blood NK cells, but impaired NK cell cytotoxic activity. This was not due to a generalized defect in cytotoxicity because antibody-dependent cellular cytotoxicity was intact. This abnormality was partially reversed by in vitro addition of IL-2, which was also able to induce NF-κB activation. In one patient with recurrent cytomegalovirus infections, administration of IL-2 partially corrected the NK cell killing deficit. These data suggest that NEMO participates in signaling pathways leading to NK cell cytotoxicity and that IL-2 can activate NF-κB and partially overcome the NK cell defect in patients with NEMO mutations.
Jordan S. Orange, Scott R. Brodeur, Ashish Jain, Francisco A. Bonilla, Lynda C. Schneider, Roberto Kretschmer, Samuel Nurko, Wendy L. Rasmussen, Julia R. Köhler, Stephen E. Gellis, Betsy M. Ferguson, Jack L. Strominger, Jonathan Zonana, Narayanaswamy Ramesh, Zuhair K. Ballas, Raif S. Geha
The tight-skin (TSK/+) mouse, a genetic model for human systemic sclerosis (SSc), develops cutaneous fibrosis and autoantibodies against SSc-specific target autoantigens. Although molecular mechanisms explaining the development of fibrosis and autoimmunity in SSc patients or TSK/+ mice remain unknown, we recently demonstrated that SSc patients overexpress CD19, an important regulatory molecule expressed by B lymphocytes. B cells from CD19-deficient mice are hyporesponsive to transmembrane signals, while B cells overexpressing CD19 are hyperresponsive and generate autoantibodies. In this study, TSK/+ B cells also exhibited a hyperresponsive phenotype with decreased surface IgM expression, enhanced serum Ig production, and spontaneous autoantibody production. Moreover, CD19 tyrosine phosphorylation was constitutively augmented in TSK/+ B cells. CD19-mediated [Ca2+]i responses, Vav phosphorylation, and Lyn kinase activity were similarly enhanced. Studies of TSK/+ mice deficient in CD19 expression demonstrated that CD19 deficiency significantly decreased skin fibrosis in TSK/+ mice. Additionally, CD19 loss in TSK/+ mice upregulated surface IgM expression and completely abrogated hyper-γ-globulinemia and autoantibody production. CD19 deficiency also inhibited IL-6 production by TSK/+ B cells. Thus, chronic B cell activation resulting from augmented CD19 signaling in TSK/+ mice leads to skin sclerosis possibly through IL-6 overproduction as well as autoimmunity.
Eriko Saito, Manabu Fujimoto, Minoru Hasegawa, Kazuhiro Komura, Yasuhito Hamaguchi, Yuko Kaburagi, Tetsuya Nagaoka, Kazuhiko Takehara, Thomas F. Tedder, Shinichi Sato
Deficiency of the membrane protein FAT/CD36 causes a marked defect in fatty acid uptake by various tissues and is genetically linked to insulin resistance in rats and humans. Here, we examined insulin responsiveness of CD36–/– mice. When fed a diet high in complex carbohydrates and low (5%) in fat, these animals cleared glucose faster than the wild-type. In vivo, uptake of 2-fluorodeoxyglucose by muscle was increased severalfold, and in vitro, insulin responsiveness of glycogenesis by the soleus was enhanced. Null mice had lower glycogen levels in muscle and liver, lower muscle triglyceride levels, and increased liver triglyceride content—all findings consistent with increased insulin-sensitivity. However, when the chow diet was switched to one high in fructose, CD36–/– mice but not wild-type mice developed marked glucose intolerance, hyperinsulinemia, and decreased muscle glucose uptake. High-fat diets impaired glucose tolerance equally in both groups, although CD36 deficiency helped moderate insulin-responsive muscle glucose oxidation. In conclusion, CD36 deficiency enhances insulin responsiveness on a high-starch, low-fat diet. It predisposes to insulin resistance induced by high fructose and partially protects from that induced by high-fat diets. In humans, CD36 deficiency may be an important factor in the metabolic adaptation to diet and in susceptibility to some forms of diet-induced pathology.
Tahar Hajri, Xiao Xia Han, Arend Bonen, Nada A. Abumrad
Becker syndrome, a recessive nondystrophic myotonia caused by mutations in the chloride channel 1 gene (CLCN1), is characterized by delayed muscle relaxation after contraction. The ADR (arrested development of righting response) mouse is an animal model for Becker syndrome. Skeletal muscles from ADR myotonic animals show an increased number of oxidative fibers with a lack of glycolytic fibers as well as signs of muscle hypertrophy. Through breeding ADR myotonic mice with mice harboring a MEF2-dependent reporter gene, we found that the transcriptional activity of MEF2 was dramatically enhanced in myotonic muscles. Post-translational induction of MEF2 transcriptional activity correlated with the activation of p38 MAPK and did not affect MEF2 DNA-binding affinity. Expression of class II histone deacetylases (HDACs), which repress MEF2-dependent gene expression, was significantly reduced in skeletal muscles from myotonic mice. These findings suggest that the combined effects of class II HDAC deficiency and p38 MAPK activation lead to potent upregulation of MEF2 transcriptional activity, which contributes to the long-term changes in gene expression and fiber-type transformation observed in myotonic skeletal muscles. These findings provide new molecular targets for potential treatment of congenital myotonia.
Hai Wu, Eric N. Olson
Pseudophosphatases display extensive sequence similarities to phosphatases but harbor amino acid alterations in their active-site consensus motifs that render them catalytically inactive. A potential role in substrate trapping or docking has been proposed, but the specific requirements for pseudophosphatases during development and differentiation are unknown. We demonstrate here that Sbf1, a pseudophosphatase of the myotubularin family, is expressed at high levels in seminiferous tubules of the testis, specifically in Sertoli’s cells, spermatogonia, and pachytene spermatocytes, but not in postmeiotic round spermatids. Mice that are nullizygous for Sbf1 exhibit male infertility characterized by azoospermia. The onset of the spermatogenic defect occurs in the first wave of spermatogenesis at 17 days after birth during the synchronized progression of pachytene spermatocytes to haploid spermatids. Vacuolation of the Sertoli’s cells is the earliest observed phenotype and is followed by reduced formation of spermatids and eventual depletion of the germ cell compartment in older mice. The nullizygous phenotype in conjunction with high-level expression of Sbf1 in premeiotic germ cells and Sertoli’s cells is consistent with a crucial role for Sbf1 in transition from diploid to haploid spermatocytes. These studies demonstrate an essential role for a pseudophosphatase and implicate signaling pathways regulated by myotubularin family proteins in spermatogenesis and germ cell differentiation.
Ron Firestein, Peter L. Nagy, Megan Daly, Phil Huie, Marco Conti, Michael L. Cleary
Gaucher disease, the most common lysosomal storage disease, is caused by a deficiency of glucocerebrosidase resulting in the impairment of glucosylceramide degradation. The hallmark of the disease is the presence of the Gaucher cell, a macrophage containing much of the stored glucosylceramide found in tissues, which is believed to cause many of the clinical manifestations of the disease. We have developed adult mice carrying the Gaucher disease L444P point mutation in the glucocerebrosidase (Gba) gene and exhibiting a partial enzyme deficiency. The mutant mice demonstrate multisystem inflammation, including evidence of B cell hyperproliferation, an aspect of the disease found in some patients. However, the mutant mice do not accumulate large amounts of glucosylceramide or exhibit classic Gaucher cells in tissues.
Hiroki Mizukami, Yide Mi, Ryuichi Wada, Mari Kono, Tadashi Yamashita, Yujing Liu, Norbert Werth, Roger Sandhoff, Konrad Sandhoff, Richard L. Proia
The treatment of chronic inflammatory diseases is complicated by their unpredictable, relapsing clinical course. Here, we describe a new strategy in which an inflammation-regulated therapeutic transgene is introduced into the joints to prevent recurrence of arthritis. To this end, we designed a recombinant adenoviral vector containing a two-component, inflammation-inducible promoter controlling the expression of human IL-10 (hIL-10) cDNA. When tested in vitro, this system had a low-level basal activity and was activated four to five orders of magnitude by various inflammatory stimuli, including TNF-α, IL-1β, IL-6, and LPS. When introduced in joints of rats with recurrent streptococcal cell wall–induced arthritis, the IL-10 transgene was induced in parallel with disease recurrence and effectively prevented the influx of inflammatory cells and the associated swelling of the joints. Levels of inflammation-inducible hIL-10 protein within the joints correlated closely with the severity of recurrence. An endogenously regulated therapeutic transgene can thus establish negative feedback and restore homeostasis in vivo while minimizing host exposure to the recombinant drug.
A.V. Miagkov, A.W. Varley, R.S. Munford, S.S. Makarov
Types A and B Niemann-Pick disease (NPD) are lysosomal storage disorders resulting from loss of acid sphingomyelinase (ASM) activity. We have used a knockout mouse model of NPD (ASMKO mice) to evaluate the effects of direct intracerebral transplantation of bone marrow–derived mesenchymal stem cells (MSCs) on the progression of neurological disease in this disorder. MSCs were transduced with a retroviral vector to overexpress ASM and were injected into the hippocampus and cerebellum of 3-week-old ASMKO pups. Transplanted cells migrated away from the injection sites and survived at least 6 months after transplantation. Seven of 8 treated mice, but none of the untreated controls, survived for ≥ 7 months after transplant. Survival times were greater in sex-matched than in sex-mismatched transplants. Transplantation significantly delayed the Purkinje cell loss that is characteristic of NPD, although the protective effect declined with distance from the injection site. Overall ASM activity in brain homogenates was low, but surviving Purkinje cells contained the retrovirally expressed human enzyme, and transplanted animals showed a reduction in cerebral sphingomyelin. These results reveal the potential of treating neurodegenerative lysosomal storage disorders by intracerebral transplantation of bone marrow–derived MSCs.
Hee Kyung Jin, Janet E. Carter, George W. Huntley, Edward H. Schuchman
LMX1B encodes a LIM-homeodomain transcription factor. Mutations in LMX1B cause nail-patella syndrome (NPS), an autosomal dominant disease with skeletal abnormalities, nail hypoplasia, and nephropathy. Expression of glomerular basement membrane (GBM) collagens is reduced in Lmx1b–/– mice, suggesting one basis for NPS nephropathy. Here, we show that Lmx1b–/– podocytes have reduced numbers of foot processes, are dysplastic, and lack typical slit diaphragms, indicating an arrest in development. Using antibodies to podocyte proteins important for podocyte function, we found that Lmx1b–/– podocytes express near-normal levels of nephrin, synaptopodin, ZO-1, α3 integrin, and GBM laminins. However, mRNA and protein levels for CD2AP and podocin were greatly reduced, suggesting a cooperative role for these molecules in foot process and slit diaphragm formation. We identified several LMX1B binding sites in the putative regulatory regions of both CD2AP and NPHS2 (podocin) and demonstrated that LMX1B binds to these sequences in vitro and can activate transcription through them in cotransfection assays. Thus, LMX1B regulates the expression of multiple podocyte genes critical for podocyte differentiation and function. Our results indicate that reduced levels of proteins associated with foot processes and the glomerular slit diaphragm likely contribute, along with reduced levels of GBM collagens, to the nephropathy associated with NPS.
Jeffrey H. Miner, Roy Morello, Kaya L. Andrews, Cong Li, Corinne Antignac, Andrey S. Shaw, Brendan Lee
Patients with nail-patella syndrome often suffer from a nephropathy, which ultimately results in chronic renal failure. The finding that this disease is caused by mutations in the transcription factor LMX1B, which in the kidney is expressed exclusively in podocytes, offers the opportunity for a better understanding of the renal pathogenesis. In our analysis of the nephropathy in nail-patella syndrome, we have made use of the Lmx1b knockout mouse. Transmission electron micrographs showed that glomerular development in general and the differentiation of podocytes in particular were severely impaired. The glomerular capillary network was poorly elaborated, fenestrae in the endothelial cells were largely missing, and the glomerular basement membrane was split. In addition podocytes retained a cuboidal shape and did not form foot processes and slit diaphragms. Expression of the α4 chain of collagen IV and of podocin was also severely reduced. Using gel shift assays, we demonstrated that LMX1B bound to two AT-rich sequences in the promoter region of NPHS2, the gene encoding podocin. Our results demonstrate that Lmx1b regulates important steps in glomerular development and establish a link between three hereditary kidney diseases: nail-patella syndrome (Lmx1b), steroid-resistant nephrotic syndrome (podocin), and Alport syndrome (collagen IV α4).
Claudia Rohr, Jürgen Prestel, Laurence Heidet, Hiltraud Hosser, Wilhelm Kriz, Randy L. Johnson, Corinne Antignac, Ralph Witzgall
Dominant mutations in sarcomere protein genes cause hypertrophic cardiomyopathy, an inherited human disorder with increased ventricular wall thickness, myocyte hypertrophy, and disarray. To understand the early consequences of mutant sarcomere proteins, we have studied mice (designated αMHC403/+) bearing an Arg403Gln missense mutation in the α cardiac myosin heavy chain. We demonstrate that Ca2+ is reduced in the sarcoplasmic reticulum of αMHC403/+ mice, and levels of the sarcoplasmic reticulum Ca2+-binding protein calsequestrin are diminished in advance of changes in cardiac histology or morphology. Further evidence for dysregulation of sarcoplasmic reticulum Ca2+ in these animals is seen in their decreased expression of the ryanodine receptor Ca2+-release channel and its associated membrane proteins and in an increase in ryanodine receptor phosphorylation. Early administration of the L-type Ca2+ channel inhibitor diltiazem restores normal levels of these sarcoplasmic reticular proteins and prevents the development of pathology in αMHC403/+ mice. We conclude that disruption of sarcoplasmic reticulum Ca2+ homeostasis is an important early event in the pathogenesis of this disorder and suggest that the use of Ca2+ channel blockers in advance of established clinical disease could prevent hypertrophic cardiomyopathy caused by sarcomere protein gene mutations.
Christopher Semsarian, Imran Ahmad, Michael Giewat, Dimitrios Georgakopoulos, Joachim P. Schmitt, Bradley K. McConnell, Steven Reiken, Ulrike Mende, Andrew R. Marks, David A. Kass, Christine E. Seidman, J.G. Seidman
Regulatory subunit KCNE3 (E3) interacts with KCNQ1 (Q1) in epithelia, regulating its activation kinetics and augmenting current density. Since E3 is expressed weakly in the heart, we hypothesized that ectopic expression of E3 in cardiac myocytes might abbreviate action potential duration (APD) by interacting with Q1 and augmenting the delayed rectifier current (IK). Thus, we transiently coexpressed E3 with Q1 and KCNE1 (E1) in Chinese hamster ovary cells and found that E3 coexpression increased outward current at potentials by ≥ –80 mV and accelerated activation. We then examined the changes in cardiac electrophysiology following injection of adenovirus-expressed E3 into the left ventricular cavity of guinea pigs. After 72 hours, the corrected QT interval of the electrocardiogram was reduced by ∼10%. APD was reduced by >3-fold in E3-transduced cells relative to controls, while E-4031–insensitive IK and activation kinetics were significantly augmented. Based on quantitative modeling of a transmural cardiac segment, we demonstrate that the degree of QT interval abbreviation observed results from electrotonic interactions in the face of limited transduction efficiency and that heterogeneous transduction of E3 may actually potentiate arrhythmias. Provided that fairly homogeneous ectopic ventricular expression of regulatory subunits can be achieved, this approach may be useful in enhancing repolarization and in treating long QT syndrome.
Reza Mazhari, H. Bradley Nuss, Antonis A. Armoundas, Raimond L. Winslow, Eduardo Marbán
Neuropeptide Y (NPY) is a downstream modulator of leptin action, possibly at the level of the arcuate nucleus where NPY neurons are known to express both leptin receptors and Y2 receptors. In addition to the well-described role of NPY and leptin in energy balance and obesity, intracerebroventricular administration of NPY or leptin also causes bone loss. Here we show that Y2 receptor–deficient mice have a twofold increase in trabecular bone volume as well as greater trabecular number and thickness compared with control mice. We also demonstrate that central Y2 receptors are crucial for this process, since selective deletion of hypothalamic Y2 receptors in mature conditional Y2 knockout mice results in an identical increase in trabecular bone volume within 5 weeks. This hypothalamus-specific Y2 receptor deletion stimulates osteoblast activity and increases the rate of bone mineralization and formation, with no effect on osteoblast or osteoclast surface measurements. The lack of any changes in plasma total calcium, leptinemia, or hypothalamo-pituitary-corticotropic, -thyrotropic, -somatotropic, or -gonadotropic output suggests that Y2 receptors do not modulate bone formation by humoral mechanisms, and that alteration of autonomic function through hypothalamic Y2 receptors may play a key role in a major central regulatory circuit of bone formation.
Paul A. Baldock, Amanda Sainsbury, Michelle Couzens, Ronaldo F. Enriquez, Gethin P. Thomas, Edith M. Gardiner, Herbert Herzog
Based on studies by our group and others, we hypothesized that IL-7 may possess antifibrotic activities in an IFN-γ–dependent and independent manner. Here, we have evaluated the antifibrotic therapeutic potential of IL-7 in both in vitro and in vivo pulmonary fibrosis models. IL-7 inhibited both TGF-β production and signaling in fibroblasts and required an intact JAK1/STAT1 signal transduction pathway. IL-7–mediated inhibition of TGF-β signaling was found to be associated with an increase in Smad7, a major inhibitory regulator in the SMAD family. In the presence of IL-7, Smad7 dominant negative fibroblasts restored TGF-β–induced collagen synthesis, indicating that an IL-7–mediated increase in Smad7 suppressed TGF-β signaling. Consistent with these in vitro findings, recombinant IL-7 decreased bleomycin-induced pulmonary fibrosis in vivo, independent of IFN-γ. The antifibrotic activities of IL-7 merit further basic and clinical investigation for the treatment of pulmonary fibrosis.
Min Huang, Sherven Sharma, Li X. Zhu, Michael P. Keane, Jie Luo, Ling Zhang, Marie D. Burdick, Ying Q. Lin, Mariam Dohadwala, Brian Gardner, Raj K. Batra, Robert M. Strieter, Steven M. Dubinett
Increased inducible nitric oxide synthase (iNOS) expression is a component of the immune response and has been demonstrated in cardiomyocytes in septic shock, myocarditis, transplant rejection, ischemia, and dilated cardiomyopathy. To explore whether the consequences of such expression are adaptive or pathogenic, we have generated a transgenic mouse model conditionally targeting the expression of a human iNOS cDNA to myocardium. Chronic cardiac-specific upregulation of iNOS in transgenic mice led to increased production of peroxynitrite. This was associated with a mild inflammatory cell infiltrate, cardiac fibrosis, hypertrophy, and dilatation. While iNOS-overexpressing mice infrequently developed overt heart failure, they displayed a high incidence of sudden cardiac death due to bradyarrhythmia. This dramatic cardiac phenotype was rescued by specific attenuation of transgene activity. These data implicate cardiomyocyte iNOS overexpression as sufficient to cause cardiomyopathy, bradyarrhythmia, and sudden cardiac death.
Imran N. Mungrue, Robert Gros, Xiaomang You, Asif Pirani, Azar Azad, Tamas Csont, Richard Schulz, Jagdish Butany, Duncan J. Stewart, Mansoor Husain
To investigate the physiological role of the α1D-adrenergic receptor (α1D-AR) subtype, we created mice lacking the α1D-AR (α1D–/–) by gene targeting and characterized their cardiovascular function. In α1D–/– mice, the RT-PCR did not detect any transcript of the α1D-AR in any tissue examined, and there was no apparent upregulation of other α1-AR subtypes. Radioligand binding studies showed that α1-AR binding capacity in the aorta was lost, while that in the heart was unaltered in α1D–/– mice. Non-anesthetized α1D–/– mice maintained significantly lower basal systolic and mean arterial blood pressure conditions, relative to wild-type mice, and they showed no significant change in heart rate or in cardiac function, as assessed by echocardiogram. Besides hypotension, the pressor responses to phenylephrine and norepinephrine were decreased by 30–40% in α1D–/– mice. Furthermore, the contractile response of the aorta and the pressor response of isolated perfused mesenteric arterial beds to α1-AR stimulation were markedly reduced in α1D–/– mice. We conclude that the α1D-AR participates directly in sympathetic regulation of systemic blood pressure by vasoconstriction.
Akito Tanoue, Yoshihisa Nasa, Takaaki Koshimizu, Hitomi Shinoura, Sayuri Oshikawa, Takayuki Kawai, Sachie Sunada, Satoshi Takeo, Gozoh Tsujimoto
Deficiency of the Golgi enzyme UDP-Gal:N-acetylglucosamine β-1,4-galactosyltransferase I (β4GalT I) (E.C.22.214.171.124) causes a new congenital disorder of glycosylation (CDG), designated type IId (CDG-IId), a severe neurologic disease characterized by a hydrocephalus, myopathy, and blood-clotting defects. Analysis of oligosaccharides from serum transferrin by HPLC, mass spectrometry, and lectin binding revealed the loss of sialic acid and galactose residues. In skin fibroblasts and leukocytes, galactosyltransferase activity was reduced to 5% that of controls. In fibroblasts, a truncated polypeptide was detected that was about 12 kDa smaller in size than wild-type β4GalT I and that failed to localize to the Golgi apparatus. Sequencing of the β4GalT I cDNA and gene revealed an insertion of a single nucleotide (1031-1032insC) leading to premature translation stop and loss of the C-terminal 50 amino acids of the enzyme. The patient was homozygous and his parents heterozygous for this mutation. Expression of a corresponding mutant cDNA in COS-7 cells led to the synthesis of a truncated, inactive polypeptide, which localized to the endoplasmic reticulum.
Bengt Hanßke, Christian Thiel, Torben Lübke, Martin Hasilik, Stefan Höning, Verena Peters, Peter H. Heidemann, Georg F. Hoffmann, Eric G. Berger, Kurt von Figura, Christian Körner
There is increasing evidence that bacterial superantigens contribute to inflammation and T cell responses in psoriasis. Psoriatic inflammation entails a complex series of inductive and effector processes that require the regulated expression of various proinflammatory genes, many of which require NF-κB for maximal trans-activation. PS-519 is a potent and selective proteasome inhibitor based upon the naturally occurring compound lactacystin, which inhibits NF-κB activation by blocking the degradation of its inhibitory protein IκB. We report that proteasome inhibition by PS-519 reduces superantigen-mediated T cell–activation in vitro and in vivo. Proliferation was inhibited along with the expression of very early (CD69), early (CD25), and late T cell (HLA-DR) activation molecules. Moreover, expression of E-selectin ligands relevant to dermal T cell homing was reduced, as was E-selectin binding in vitro. Finally, PS-519 proved to be therapeutically effective in a SCID-hu xenogeneic psoriasis transplantation model. We conclude that inhibition of the proteasome, e.g., by PS-519, is a promising means to treat T cell–mediated disorders such as psoriasis.
Thomas M. Zollner, Maurizio Podda, Christine Pien, Peter J. Elliott, Roland Kaufmann, Wolf-Henning Boehncke