Concise Communication

Abstract

In a wide array of kidney diseases, type 1 angiotensin (AT1) receptors are present on the immune cells that infiltrate the renal interstitium. Here, we examined the actions of AT1 receptors on macrophages in progressive renal fibrosis and found that macrophage-specific AT1 receptor deficiency exacerbates kidney fibrosis induced by unilateral ureteral obstruction (UUO). Macrophages isolated from obstructed kidneys of mice lacking AT1 receptors solely on macrophages had heightened expression of proinflammatory M1 cytokines, including IL-1. Evaluation of isolated AT1 receptor–deficient macrophages confirmed the propensity of these cells to produce exaggerated levels of M1 cytokines, which led to more severe renal epithelial cell damage via IL-1 receptor activation in coculture compared with WT macrophages. A murine kidney crosstransplantation concomitant with UUO model revealed that augmentation of renal fibrosis instigated by AT1 receptor–deficient macrophages is mediated by IL-1 receptor stimulation in the kidney. This study indicates that a key role of AT1 receptors on macrophages is to protect the kidney from fibrosis by limiting activation of IL-1 receptors in the kidney.

Authors

Jian-dong Zhang, Mehul B. Patel, Robert Griffiths, Paul C. Dolber, Phillip Ruiz, Matthew A. Sparks, Johannes Stegbauer, Huixia Jin, Jose A. Gomez, Anne F. Buckley, William S. Lefler, Daian Chen, Steven D. Crowley

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Abstract

The transcription factor steroidogenic factor 1 (SF-1; also known as NR5A1) is a crucial mediator of both steroidogenic and nonsteroidogenic tissue differentiation. Mutations within SF1 underlie different disorders of sexual development (DSD), including sex reversal, spermatogenic failure, ovarian insufficiency, and adrenocortical deficiency. Here, we identified a recessive mutation within SF1 that resulted in a substitution of arginine to glutamine at codon 103 (R103Q) in a child with both severe 46,XY-DSD and asplenia. The R103Q mutation decreased SF-1 transactivation of TLX1, a transcription factor that has been shown to be essential for murine spleen development. Additionally, the SF1 R103Q mutation impaired activation of steroidogenic genes, without affecting synergistic SF-1 and sex-determining region Y (SRY) coactivation of the testis development gene SOX9. Together, our data provide evidence that SF-1 is required for spleen development in humans via transactivation of TLX1 and that mutations that only impair steroidogenesis, without altering the SF1/SRY transactivation of SOX9, can lead to 46,XY-DSD.

Authors

David Zangen, Yotam Kaufman, Ehud Banne, Ariella Weinberg-Shukron, Abdulsalam Abulibdeh, Benjamin P. Garfinkel, Dima Dweik, Moein Kanaan, Núria Camats, Christa Flück, Paul Renbaum, Ephrat Levy-Lahad

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Abstract

Taken orally, the drug dimethyl fumarate (DMF) has been shown to improve functional outcomes for patients with MS; however, it is unclear how DMF mediates a protective effect. DMF and, more so, its active metabolite, monomethyl fumarate, are known agonists of the hydroxycarboxylic acid receptor 2 (HCA2), a G protein–coupled membrane receptor. Here, we evaluated the contribution of HCA2 in mediating the protective effect afforded by DMF in EAE, a mouse model of MS. DMF treatment reduced neurological deficit, immune cell infiltration, and demyelination of the spinal cords in wild-type mice, but not in Hca2–/– mice, indicating that HCA2 is required for the therapeutic effect of DMF. In particular, DMF decreased the number of infiltrating neutrophils in a HCA2-dependent manner, likely by interfering with neutrophil adhesion to endothelial cells and chemotaxis. Together, our data indicate that HCA2 mediates the therapeutic effects of DMF in EAE. Furthermore, identification of HCA2 as a molecular target may help to optimize MS therapy.

Authors

Hui Chen, Julian C. Assmann, Antje Krenz, Mahbubur Rahman, Myriam Grimm, Christian M. Karsten, Jörg Köhl, Stefan Offermanns, Nina Wettschureck, Markus Schwaninger

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Abstract

The majority of mammalian cells have nonmotile primary cilia on their surface that act as antenna-like sensory organelles. Genetic defects that result in ciliary dysfunction are associated with obesity in humans and rodents, which suggests that functional cilia are important for controlling energy balance. Here we demonstrated that neuronal cilia lengths were selectively reduced in hypothalami of obese mice with leptin deficiency and leptin resistance. Treatment of N1 hypothalamic neuron cells with leptin stimulated cilia assembly via inhibition of the tumor suppressors PTEN and glycogen synthase kinase 3β (GSK3β). Induction of short cilia in the hypothalamus of adult mice increased food intake and decreased energy expenditure, leading to a positive energy balance. Moreover, mice with short hypothalamic cilia exhibited attenuated anorectic responses to leptin, insulin, and glucose, which indicates that leptin-induced cilia assembly is essential for sensing these satiety signals by hypothalamic neurons. These data suggest that leptin governs the sensitivity of hypothalamic neurons to metabolic signals by controlling the length of the cell’s antenna.

Authors

Yu Mi Han, Gil Myoung Kang, Kyunghee Byun, Hyuk Wan Ko, Joon Kim, Mi-Seon Shin, Hyun-Kyong Kim, So Young Gil, Ji Hee Yu, Bonghee Lee, Min-Seon Kim

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Abstract

Targeted cancer therapies often induce “outlier” responses in molecularly defined patient subsets. One patient with advanced-stage lung adenocarcinoma, who was treated with oral sorafenib, demonstrated a near-complete clinical and radiographic remission for 5 years. Whole-genome sequencing and RNA sequencing of primary tumor and normal samples from this patient identified a somatic mutation, ARAF S214C, present in the cancer genome and expressed at high levels. Additional mutations affecting this residue of ARAF and a nearby residue in the related kinase RAF1 were demonstrated across 1% of an independent cohort of lung adenocarcinoma cases. The ARAF mutations were shown to transform immortalized human airway epithelial cells in a sorafenib-sensitive manner. These results suggest that mutant ARAF is an oncogenic driver in lung adenocarcinoma and an indicator of sorafenib response.

Authors

Marcin Imielinski, Heidi Greulich, Bethany Kaplan, Luiz Araujo, Joseph Amann, Leora Horn, Joan Schiller, Miguel A. Villalona-Calero, Matthew Meyerson, David P. Carbone

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Abstract

Autologous hematopoietic stem cell transplantation (HSCT) is commonly employed for hematologic and non-hematologic malignancies. In clinical trials, HSCT has been evaluated for severe autoimmunity as a method to “reset” the immune system and produce a new, non-autoimmune repertoire. While the feasibility of eliminating the vast majority of mature T cells is well established, accurate and quantitative determination of the relationship of regenerated T cells to the baseline repertoire has been difficult to assess. Here, in a phase II study of HSCT for poor-prognosis multiple sclerosis, we used high-throughput deep TCRβ chain sequencing to assess millions of individual TCRs per patient sample. We found that HSCT has distinctive effects on CD4+ and CD8+ T cell repertoires. In CD4+ T cells, dominant TCR clones present before treatment were undetectable following reconstitution, and patients largely developed a new repertoire. In contrast, dominant CD8+ clones were not effectively removed, and the reconstituted CD8+ T cell repertoire was created by clonal expansion of cells present before treatment. Importantly, patients who failed to respond to treatment had less diversity in their T cell repertoire early during the reconstitution process. These results demonstrate that TCR characterization during immunomodulatory treatment is both feasible and informative, and may enable monitoring of pathogenic or protective T cell clones following HSCT and cellular therapies.

Authors

Paolo A. Muraro, Harlan Robins, Sachin Malhotra, Michael Howell, Deborah Phippard, Cindy Desmarais, Alessandra de Paula Alves Sousa, Linda M. Griffith, Noha Lim, Richard A. Nash, Laurence A. Turka

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Abstract

Chronic rejection is the primary cause of long-term failure of transplanted organs and is often viewed as an antibody-dependent process. Chronic rejection, however, is also observed in mice and humans with no detectable circulating alloantibodies, suggesting that antibody-independent pathways may also contribute to pathogenesis of transplant rejection. Here, we have provided direct evidence that chronic rejection of vascularized heart allografts occurs in the complete absence of antibodies, but requires the presence of B cells. Mice that were deficient for antibodies but not B cells experienced the same chronic allograft vasculopathy (CAV), which is a pathognomonic feature of chronic rejection, as WT mice; however, mice that were deficient for both B cells and antibodies were protected from CAV. B cells contributed to CAV by supporting splenic lymphoid architecture, T cell cytokine production, and infiltration of T cells into graft vessels. In chimeric mice, in which B cells were present but could not present antigen, both T cell responses and CAV were markedly reduced. These findings establish that chronic rejection can occur in the complete absence of antibodies and that B cells contribute to this process by supporting T cell responses through antigen presentation and maintenance of lymphoid architecture.

Authors

Qiang Zeng, Yue-Harn Ng, Tripti Singh, Ke Jiang, Khaleefathullah A. Sheriff, Renee Ippolito, Salwa Zahalka, Qi Li, Parmjeet Randhawa, Rosemary A. Hoffman, Balathiripurasundari Ramaswami, Frances E. Lund, Geetha Chalasani

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Abstract

Children with focal hyperinsulinism of infancy display a dramatic, non-neoplastic clonal expansion of β cells that have undergone mitotic recombination, resulting in paternal disomy of part of chromosome 11. This disomic region contains imprinted genes, including the gene encoding the cell cycle inhibitor p57Kip2 (CDKN1C), which is silenced as a consequence of the recombination event. We hypothesized that targeting p57Kip2 could stimulate adult human β cell replication. Indeed, when we suppressed CDKN1C expression in human islets obtained from deceased adult organ donors and transplanted them into hyperglycemic, immunodeficient mice, β cell replication increased more than 3-fold. The newly replicated cells retained properties of mature β cells, including the expression of β cell markers such as insulin, PDX1, and NKX6.1. Importantly, these newly replicated cells demonstrated normal glucose-induced calcium influx, further indicating β cell functionality. These findings provide a molecular explanation for the massive β cell replication that occurs in children with focal hyperinsulinism. These data also provided evidence that β cells from older humans, in which baseline replication is negligible, can be coaxed to re-enter and complete the cell cycle while maintaining mature β cell properties. Thus, controlled manipulation of this pathway holds promise for the expansion of β cells in patients with type 2 diabetes.

Authors

Dana Avrahami, Changhong Li, Ming Yu, Yang Jiao, Jia Zhang, Ali Naji, Seyed Ziaie, Benjamin Glaser, Klaus H. Kaestner

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Abstract

The effector activity of antibodies is dependent on engagement with Fcγ receptors (FcγRs) and activation of the associated intracellular signaling pathways. Preclinical evaluation of therapeutic humanized or chimeric mAbs to study the interactions of their Fc regions with FcγRs is hampered by substantial structural and functional FcγR diversity among species. In this report, we used mice expressing only human FcγRs to evaluate the contribution of FcγR-mediated pathways to the neutralizing activity of an anti-anthrax toxin chimeric mAb. We observed that the protective activity of this mAb was highly dependent upon FcγR engagement, with minimal protection against anthrax toxin observed in FcγR-deficient mice following mAb administration. We generated anti-anthrax toxin mAbs with specific Fc domain variants with selectively enhanced affinity for particular human FcγRs and assessed their activity in FcγR-humanized mice. We determined that Fc domain variants that were capable of selectively engaging activating FcγRs substantially enhanced the in vitro and in vivo activity of anthrax toxin-neutralizing antibodies. These findings indicate that the application of Fc domain engineering is a feasible strategy to enhance toxin-neutralizing activity and suggest that engineered antitoxin antibodies will have improved therapeutic efficacy.

Authors

Stylianos Bournazos, Siu-Kei Chow, Nareen Abboud, Arturo Casadevall, Jeffrey V. Ravetch

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Abstract

Aniridia is a congenital and progressive panocular condition with poor visual prognosis that is associated with brain, olfactory, and pancreatic abnormalities. Development of aniridia is linked with nonsense mutations that result in paired box 6 (PAX6) haploinsufficiency. Here, we used a mouse model of aniridia to test the hypothesis that manipulation of Pax6 dosage through a mutation-independent nonsense mutation suppression strategy would limit progressive, postnatal damage in the eye. We focused on the nonsense suppression drugs 3-[5-(2-fluorophenyl)-1,2,4-oxadiazol-3-yl]benzoic acid (ataluren) and gentamicin. Remarkably, we demonstrated that nonsense suppression not only inhibited disease progression but also stably reversed corneal, lens, and retinal malformation defects and restored electrical and behavioral responses of the retina. The most successful results were achieved through topical application of the drug formulation START (0.9% sodium chloride, 1% Tween 80, 1% powdered ataluren, 1% carboxymethylcellulose), which was designed to enhance particle dispersion and to increase suspension viscosity. These observations suggest that the eye retains marked developmental plasticity into the postnatal period and remains sensitive to molecular remodeling. Furthermore, these data indicate that other neurological developmental anomalies associated with dosage-sensitive genetic mutations may be reversible through nonsense suppression therapeutics.

Authors

Cheryl Y. Gregory-Evans, Xia Wang, Kishor M. Wasan, Jinying Zhao, Andrew L. Metcalfe, Kevin Gregory-Evans

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