Recently published - More

Abstract

Despite recent therapeutic advances, prostate cancer remains a leading cause of cancer-related death. A subset of castration-resistant prostate cancers become androgen receptor (AR) signaling independent and develop neuroendocrine prostate cancer (NEPC) features through lineage plasticity. These NEPC tumors, associated with aggressive disease and poor prognosis, are driven, in part, by aberrant expression of N-Myc, through mechanisms that remain unclear. Integrative analysis of the N-Myc transcriptome, cistrome, and interactome using in vivo, in vitro, and ex vivo models (including patient-derived organoids) identified a lineage switch towards a neural identity associated with epigenetic reprogramming. N-Myc and known AR cofactors (e.g., FOXA1 and HOXB13) overlapped, independently of AR, at genomic loci implicated in neural lineage specification. Moreover, histone marks specifically associated with lineage-defining genes were reprogrammed by N-Myc. We also demonstrated that the N-Myc–induced molecular program accurately classifies our cohort of patients with advanced prostate cancer. Finally, we revealed the potential for enhancer of zeste homolog 2 (EZH2) inhibition to reverse the N-Myc–induced suppression of epithelial lineage genes. Altogether, our data provide insights into how N-Myc regulates lineage plasticity and epigenetic reprogramming associated with lineage specification. The N-Myc signature we defined could also help predict the evolution of prostate cancer and thus better guide the choice of future therapeutic strategies.

Authors

Adeline Berger, Nicholas J. Brady, Rohan Bareja, Brian Robinson, Vincenza Conteduca, Michael A. Augello, Loredana Puca, Adnan Ahmed, Etienne Dardenne, Xiaodong Lu, Inah Hwang, Alyssa M. Bagadion, Andrea Sboner, Olivier Elemento, Jihye Paik, Jindan Yu, Christopher E. Barbieri, Noah Dephoure, Himisha Beltran, David S. Rickman

×

Abstract

Resident and inflammatory mononuclear phagocytes (MPhs) with functional plasticity in the intestine are critically involved in the pathology of inflammatory bowel diseases (IBDs), the mechanism of which remains incompletely understood. In the present study, we found that increased expression of the E3 ligase F-box and WD repeat domain–containing 7 (FBXW) in the inflamed intestine was significantly correlated with IBD severity in both human diseases and in mouse models. Myeloid Fbxw7 deficiency protected mice from colitis induced by dextran sodium sulfate (DSS) or 2,6,4-trinitrobenzene sulfonic acid (TNBS). Fbxw7 deficiency resulted in decreased production of the chemokines CCL2 and CCL7 by colonic CX3CR1hi resident macrophages and reduced the accumulation of CX3CR1int proinflammatory MPhs in colitis-affected colon tissue. Mice that received adeno-associated virus–shFbxw7 (AAV-shFbxw7) showed significantly improved survival rates and alleviation of colitis. Mechanism screening demonstrated that FBXW7 suppressed H3K27me3 modification and promoted Ccl2 and Ccl7 expression via degradation of the histone-lysine N-methyltransferase enhancer of zeste homolog 2 (EZH2) in macrophages. Taken together, our results indicate that FBXW7 degrades EZH2 and increases Ccl2 and Ccl7 in CX3CR1hi macrophages, thereby promoting the recruitment of CX3CR1int proinflammatory MPhs into local colon tissues with colitis. Targeting FBXW7 might represent a potential therapeutic approach for the treatment of intestinal inflammation.

Authors

Jia He, Yinjing Song, Gaopeng Li, Peng Xiao, Yang Liu, Yue Xue, Qian Cao, Xintao Tu, Ting Pan, Zhinong Jiang, Xuetao Cao, Lihua Lai, Qingqing Wang

×

Abstract

Induction of memory CD8+ T cells is important for controlling infections such as malaria and HIV/AIDS and for cancer immunotherapy. Accurate assessment of antigen-specific (Ag-specific) CD8+ T cells is critical for vaccine optimization and for defining correlates of protection. However, conditions for determining Ag-specific CD8+ T cell responses ex vivo using intracellular cytokine staining (ICS) may be variable, especially in humans with complex antigens. Here, we used an attenuated whole parasite malaria vaccine model in humans and various experimental infections in mice to show that the duration of antigenic stimulation and timing of brefeldin A (BFA) addition influence the magnitude of Ag-specific and bystander T cell responses. Indeed, after immunization with an attenuated whole sporozoite malaria vaccine in humans, significantly higher numbers of IFN-γ–producing memory CD8+ T cells comprising Ag-specific and bystander responses were detected when the duration of Ag stimulation prior to addition of BFA was increased. Mechanistic analyses of virus-specific CD8+ T cells in mice revealed that the increase in IFN-γ–producing CD8+ T cells was due to bystander activation of Ag-experienced memory CD8+ T cells, and correlated with the proportion of Ag-experienced CD8+ T cells in the stimulated populations. Incubation with anti-cytokine antibodies (e.g., IL-12) improved accuracy in detecting bona fide memory CD8+ T cell responses, suggesting this as the mechanism for the bystander activation. These data have important implications for accurate assessment of immune responses generated by vaccines intended to elicit protective memory CD8+ T cells.

Authors

Matthew D. Martin, Isaac J. Jensen, Andrew S. Ishizuka, Mitchell Lefebvre, Qiang Shan, Hai-Hui Xue, John T. Harty, Robert A. Seder, Vladimir P. Badovinac

×

Abstract

Sialyl Lewis A (sLeA, also known as CA19-9), a tetrasaccharide selectively and highly expressed on advanced adenocarcinomas including colon, stomach, and pancreatic cancers, has long been considered as an attractive target for active and passive vaccination. While progress in antibodies targeting tumor-associated protein antigens resulted in an impressive array of therapeutics for cancer treatment, similar progress in exploiting tumor-associated carbohydrate antigens, such as sLeA, has been hampered by the lack of a detailed understanding of the singular characteristics of these antigens. We have addressed this issue by analyzing antibodies derived from patients immunized with an sLeA/KLH vaccine. These antibodies were engineered to mediate tumor clearance in vivo in preclinical models through Fc-FcγR interactions. However, in contrast to protein antigens in which hFcγRIIIA engagement was both necessary and sufficient to mediate tumor clearance in both preclinical and clinical settings, a similar selective dependence was not seen for anti-sLeA antibodies. Thus, re-engineering the Fc portion of sLeA-targeting antibodies to broadly enhance their affinity for activating FcγRs led to an enhanced therapeutic effect. These findings will facilitate the development of more efficient anticancer therapies and further advance this promising class of therapeutic antibodies into clinical use.

Authors

Polina Weitzenfeld, Stylianos Bournazos, Jeffrey V. Ravetch

×

Abstract

Acyl-ghrelin administration increases food intake, body weight, and blood glucose. In contrast, mice lacking ghrelin or ghrelin receptors (GHSRs) exhibit life-threatening hypoglycemia during starvation-like conditions, but do not consistently exhibit overt metabolic phenotypes when given ad libitum food access. These results, and findings of ghrelin resistance in obese states, imply nutritional state dependence of ghrelin’s metabolic actions. Here, we hypothesized that liver-enriched antimicrobial peptide-2 (LEAP2), a recently characterized endogenous GHSR antagonist, blunts ghrelin action during obese states and postprandially. To test this hypothesis, we determined changes in plasma LEAP2 and acyl-ghrelin due to fasting, eating, obesity, Roux-en-Y gastric bypass (RYGB), vertical sleeve gastrectomy (VSG), oral glucose administration, and type 1 diabetes mellitus (T1DM) using humans and/or mice. Our results suggest that plasma LEAP2 is regulated by metabolic status: its levels increased with body mass and blood glucose and decreased with fasting, RYGB, and in postprandial states following VSG. These changes were mostly opposite of those of acyl-ghrelin. Furthermore, using electrophysiology, we showed that LEAP2 both hyperpolarizes and prevents acyl-ghrelin from activating arcuate NPY neurons. We predict that the plasma LEAP2/acyl-ghrelin molar ratio may be a key determinant modulating acyl-ghrelin activity in response to body mass, feeding status, and blood glucose.

Authors

Bharath K. Mani, Nancy Puzziferri, Zhenyan He, Juan A. Rodriguez, Sherri Osborne-Lawrence, Nathan P. Metzger, Navpreet Chhina, Bruce Gaylinn, Michael O. Thorner, E. Louise Thomas, Jimmy D. Bell, Kevin W. Williams, Anthony P. Goldstone, Jeffrey M. Zigman

×

Abstract

The expression of the transmembrane protein 25 gene (Tmem25) is strongly influenced by glutamate ionotropic receptor kainate type subunit 4, and its function remains unknown. Here, we showed that TMEM25 was primarily localized to late endosomes in neurons. Electrophysiological experiments suggested that the effects of TMEM25 on neuronal excitability were likely mediated by N-methyl-d-aspartate receptors. TMEM25 affected the expression of the N-methyl-d-aspartate receptor NR2B subunit and interacted with NR2B, and both were colocalized to late endosome compartments. TMEM25 induced acidification changes in lysosome compartments and accelerated the degradation of NR2B. Furthermore, TMEM25 expression was decreased in brain tissues from patients with epilepsy and epileptic mice. TMEM25 overexpression attenuated the behavioral phenotypes of epileptic seizures, whereas TMEM25 downregulation exerted the opposite effect. These results provide some insights into TMEM25 biology in the brain and the functional relationship between TMEM25 and epilepsy.

Authors

Haiqing Zhang, Xin Tian, Xi Lu, Demei Xu, Yi Guo, Zhifang Dong, Yun Li, Yuanlin Ma, Chengzhi Chen, Yong Yang, Min Yang, Yi Yang, Feng Liu, Ruijiao Zhou, Miaoqing He, Fei Xiao, Xuefeng Wang

×

Abstract

Ghrelin is a key signal driving energy seeking and storage in order to reverse energy deficit. In line with this view, the metabolic status of an organism predicts sensitivity to ghrelin, with fasting increasing and obesity decreasing ghrelin sensitivity, respectively. However, the mechanism responsible for controlling this sensitivity is unknown. In this issue of the JCI, Mani and colleagues show that plasma levels of plasma liver-enriched antimicrobial peptide-2 (LEAP2), a recently identified hormone that antagonizes the ghrelin receptor, are inversely correlated with those of plasma acyl-ghrelin under conditions of both energy deficit and energy surplus in mice and humans. Their results show that a fall in plasma LEAP2 during energy deficit facilitates the actions of acyl-ghrelin, whereas increased LEAP2 in obesity suppresses the actions of acyl-ghrelin. This important discovery helps reshape our understanding of ghrelin function and may provide a new approach to aiding weight maintenance after diet-induced weight loss.

Authors

Zane B. Andrews

×

Abstract

Nature exploits cage-like proteins for a variety of biological purposes, from molecular packaging and cargo delivery to catalysis. These cage-like proteins are of immense importance in nanomedicine due to their propensity to self-assemble from simple identical building blocks to highly ordered architecture and the design flexibility afforded by protein engineering. However, delivery of protein nanocages to the renal tubules remains a major challenge because of the glomerular filtration barrier, which effectively excludes conventional size nanocages. Here, we show that DNA-binding protein from starved cells (Dps) — the extremely small archaeal antioxidant nanocage — is able to cross the glomerular filtration barrier and is endocytosed by the renal proximal tubules. Using a model of endotoxemia, we present an example of the way in which proximal tubule–selective Dps nanocages can limit the degree of endotoxin-induced kidney injury. This was accomplished by amplifying the endogenous antioxidant property of Dps with addition of a dinuclear manganese cluster. Dps is the first-in-class protein cage nanoparticle that can be targeted to renal proximal tubules through glomerular filtration. In addition to its therapeutic potential, chemical and genetic engineering of Dps will offer a nanoplatform to advance our understanding of the physiology and pathophysiology of glomerular filtration and tubular endocytosis.

Authors

Masaki Uchida, Bernhard Maier, Hitesh Kumar Waghwani, Ekaterina Selivanovitch, S. Louise Pay, John Avera, EJun Yun, Ruben M. Sandoval, Bruce A. Molitoris, Amy Zollman, Trevor Douglas, Takashi Hato

×

Abstract

In a society where physical activity is limited and food supply is abundant, metabolic diseases are becoming a serious epidemic. Metabolic syndrome (MetS) represents a cluster of metabolically related symptoms such as obesity, hypertension, dyslipidemia, and carbohydrate intolerance, and significantly increases type 2 diabetes mellitus risk. Insulin resistance and hyperinsulinemia are consistent characteristics of MetS, but which of these features is the initiating insult is still widely debated. Regardless, both of these conditions trigger adverse responses from the pancreatic β cell, which is responsible for producing, storing, and releasing insulin to maintain glucose homeostasis. The observation that the degree of β cell dysfunction correlates with the severity of MetS highlights the need to better understand β cell dysfunction in the development of MetS. This Review focuses on the current understanding from rodent and human studies of the progression of β cell responses during the development of MetS, as well as recent findings addressing the complexity of β cell identity and heterogeneity within the islet during disease progression. The differential responses observed in β cells together with the heterogeneity in disease phenotypes within the patient population emphasize the need to better understand the mechanisms behind β cell adaptation, identity, and dysfunction in MetS.

Authors

Laura I. Hudish, Jane E.B. Reusch, Lori Sussel

×


Abstract

Deep brain stimulation (DBS) is used to treat multiple neuropsychiatric disorders, including Parkinson’s disease (PD). Despite widespread clinical use, its therapeutic mechanisms are unknown. Here, we developed a mouse model of subthalamic nucleus (STN) DBS for PD, to permit investigation using cell type–specific tools available in mice. We found that electrical STN DBS relieved bradykinesia, as measured by movement velocity. In addition, our model recapitulated several hallmarks of human STN DBS, including rapid onset and offset, frequency dependence, dyskinesia at higher stimulation intensity, and associations among electrode location, therapeutic benefit, and side effects. We used this model to assess whether high-frequency stimulation is necessary for effective STN DBS and whether low-frequency stimulation can be effective when paired with compensatory adjustments in other parameters. We found that low-frequency stimulation, paired with greater pulse width and amplitude, relieved bradykinesia. Moreover, a composite metric incorporating pulse width, amplitude, and frequency predicted therapeutic efficacy better than frequency alone. We found a similar relationship between this composite metric and movement speed in a retrospective analysis of human data, suggesting that correlations observed in the mouse model may extend to human patients. Together, these data establish a mouse model for elucidating mechanisms of DBS.

Authors

Jonathan S. Schor, Alexandra B. Nelson

×

Abstract

A population of NK cells expressing the activating receptor NKG2C and the maturation marker CD57 expands in response to human CMV (HCMV) infection. CD3–CD56dimCD57+NKG2C+ NK cells are similar to CD8+ memory T cells with rapid and robust effector function upon restimulation, persistence, and epigenetic remodeling of the IFNG locus. Chronic antigen stimulation drives CD8+ memory T cell proliferation, while also inducing genome-wide epigenetic reprograming and dysfunction. We hypothesized that chronic stimulation could similarly induce epigenetic reprograming and dysfunction in NK cells. Here, we show that chronic stimulation of adaptive NK cells through NKG2C using plate-bound agonistic Abs in combination with IL-15 drove robust proliferation and activation of CD3–CD56dimCD57+NKG2C+ NK cells, while simultaneously inducing high expression of the checkpoint inhibitory receptors LAG-3 and PD-1. Marked induction of checkpoint inhibitory receptors was also observed on the surface of adaptive NK cells cocultured with HCMV-infected endothelial cells. Chronically stimulated adaptive NK cells were dysfunctional when challenged with tumor targets. These cells exhibited a pattern of epigenetic reprograming, with genome-wide alterations in DNA methylation. We believe our study has important implications for cancer immunotherapy and propose that exhausted NK cells could be targeted with inhibitory checkpoint receptor blockade.

Authors

Aimee Merino, Bin Zhang, Philip Dougherty, Xianghua Luo, Jinhua Wang, Bruce R. Blazar, Jeffrey S. Miller, Frank Cichocki

×

Abstract

Although joint pain in rheumatoid arthritis (RA) is conventionally thought to result from inflammation, arthritis pain and joint inflammation are at least partially uncoupled. This suggests that additional pain mechanisms in RA remain to be explored. Here we show that FcγRI, an immune receptor for IgG immune complex (IgG-IC), is expressed in a subpopulation of joint sensory neurons and that, under naive conditions, FcγRI cross-linking by IgG-IC directly activates the somata and peripheral terminals of these neurons to evoke acute joint hypernociception without obvious concurrent joint inflammation. These effects were diminished in both global and sensory neuron–specific Fcgr1-knockout mice. In murine models of inflammatory arthritis, FcγRI signaling was upregulated in joint sensory neurons. Acute blockade or global genetic deletion of Fcgr1 significantly attenuated arthritis pain and hyperactivity of joint sensory neurons without measurably altering joint inflammation. Conditional deletion of Fcgr1 in sensory neurons produced similar analgesic effects in these models. We therefore suggest that FcγRI expressed in sensory neurons contributes to arthritis pain independently of its functions in inflammatory cells. These findings expand our understanding of the immunosensory capabilities of sensory neurons and imply that neuronal FcγRI merits consideration as a target for treating RA pain.

Authors

Li Wang, Xiaohua Jiang, Qin Zheng, Sang-Min Jeon, Tiane Chen, Yan Liu, Heather Kulaga, Randall Reed, Xinzhong Dong, Michael J. Caterina, Lintao Qu

×

Abstract

Shwachman-Diamond Syndrome (SDS) is a rare and clinically heterogeneous bone marrow (BM) failure syndrome caused by mutations in the Shwachman-Bodian-Diamond Syndrome (SBDS) gene. Although SDS was described more than 50 years ago, its molecular pathogenesis is poorly understood due, in part, to the rarity and heterogeneity of the affected hematopoietic progenitors. To address this, we used single-cell RNA sequencing to profile scant hematopoietic stem and progenitor cells from patients with SDS. We generated a single-cell map of early lineage commitment and found that SDS hematopoiesis was left-shifted with selective loss of granulocyte-monocyte progenitors. Transcriptional targets of transforming growth factor beta (TGF-β) were dysregulated in SDS hematopoietic stem cells and multipotent progenitors, but not in lineage-committed progenitors. TGF-β inhibitors (AVID200 and SD208) increased hematopoietic colony formation of SDS patient BM. Finally, TGF-β3 and other TGF-β pathway members were elevated in SDS patient blood plasma. These data establish the TGF-β pathway as a candidate biomarker and therapeutic target in SDS and translate insights from single-cell biology into a potential therapy.

Authors

Cailin E. Joyce, Assieh Saadatpour, Melisa Ruiz-Gutierrez, Ozge Vargel Bolukbasi, Lan Jiang, Dolly D. Thomas, Sarah Young, Inga Hofmann, Colin A. Sieff, Kasiani C. Myers, Jennifer Whangbo, Towia A. Libermann, Chad Nusbaum, Guo-Cheng Yuan, Akiko Shimamura, Carl D. Novina

×

Abstract

Poroma is a benign skin tumor exhibiting terminal sweat gland duct differentiation. The present study aimed to explore the potential role of gene fusions in the tumorigenesis of poromas. RNA sequencing and reverse transcription PCR identified highly recurrent YAP1-MAML2 and YAP1-NUTM1 fusions in poromas (92/104 lesions, 88.5%) and their rare malignant counterpart, porocarcinomas (7/11 lesions, 63.6%). A WWTR1-NUTM1 fusion was identified in a single lesion of poroma. Fluorescence in situ hybridization confirmed genomic rearrangements involving these genetic loci. Immunohistochemical staining could readily identify the YAP1 fusion products as nuclear expression of the N-terminal portion of YAP1 with a lack of the C-terminal portion. YAP1 and WWTR1, also known as YAP and TAZ, respectively, encode paralogous transcriptional activators of TEAD, which are negatively regulated by the Hippo signaling pathway. The YAP1 and WWTR1 fusions strongly transactivated a TEAD reporter and promoted anchorage-independent growth, confirming their tumorigenic roles. Our results demonstrate the frequent presence of transforming YAP1 fusions in poromas and porocarcinomas and suggest YAP1/TEAD-dependent transcription as a candidate therapeutic target against porocarcinoma.

Authors

Shigeki Sekine, Tohru Kiyono, Eijitsu Ryo, Reiko Ogawa, Susumu Wakai, Hitoshi Ichikawa, Koyu Suzuki, Satoru Arai, Koji Tsuta, Mitsuaki Ishida, Yuko Sasajima, Naoki Goshima, Naoya Yamazaki, Taisuke Mori

×

Abstract

Identifying the factors driving disease disparities between males and females with multiple sclerosis (MS) holds great promise for deciphering immunopathogenic disease mechanisms. In this issue of JCI, Itoh et al. explore the basis for sexual dimorphism in autoimmunity, specifically in MS. Using the experimental autoimmune encephalomyelitis (EAE) model of MS, which recapitulates CD4+ T cell–dependent disease, the authors examined the contribution of Kdm6a, a histone demethylase gene known to escape X inactivation. Conditional knockout in CD4+ T cells revealed Kdm6a involvement with a collection of immunologic processes having the potential to skew immunity toward inflammatory responses. This study concisely shows the value of X chromosome gene expression in T cell regulation of autoimmunity and the relevance of Kdm6a in the pathogenesis of EAE as a model of MS.

Authors

Gregory F. Wu

×

Abstract

Clostridioides difficile is a significant public health threat, and diagnosis of this infection is challenging due to a lack of sensitivity in current diagnostic testing. In this issue of the JCI, Robinson et al. use a logistic regression model based on the fecal metabolome that is able to distinguish between patients with non–C. difficile diarrhea and C. difficile infection, and to some degree, patients who are asymptomatically colonized with C. difficile. The authors construct a metabolic definition of human C. difficile infection, which could improve diagnostic accuracy and aid in the development of targeted therapeutics against this pathogen.

Authors

Casey M. Theriot, Joshua R. Fletcher

×

Abstract

We previously generated 32 rotavirus-specific (RV-specific) recombinant monoclonal antibodies (mAbs) derived from B cells isolated from human intestinal resections. Twenty-four of these mAbs were specific for the VP8* fragment of RV VP4, and most (20 of 24) were non-neutralizing when tested in the conventional MA104 cell–based assay. We reexamined the ability of these mAbs to neutralize RVs in human intestinal epithelial cells including ileal enteroids and HT-29 cells. Most (18 of 20) of the “non-neutralizing” VP8* mAbs efficiently neutralized human RV in HT-29 cells or enteroids. Serum RV neutralization titers in adults and infants were significantly higher in HT-29 than MA104 cells and adsorption of these sera with recombinant VP8* lowered the neutralization titers in HT-29 but not MA104 cells. VP8* mAbs also protected suckling mice from diarrhea in an in vivo challenge model. X-ray crystallographic analysis of one VP8* mAb (mAb9) in complex with human RV VP8* revealed that the mAb interaction site was distinct from the human histo-blood group antigen binding site. Since MA104 cells are the most commonly used cell line to detect anti-RV neutralization activity, these findings suggest that prior vaccine and other studies of human RV neutralization responses may have underestimated the contribution of VP8* antibodies to the overall neutralization titer.

Authors

Ningguo Feng, Liya Hu, Siyuan Ding, Mrinmoy Sanyal, Boyang Zhao, Banumathi Sankaran, Sasirekha Ramani, Monica McNeal, Linda L. Yasukawa, Yanhua Song, B.V. Venkatar Prasad, Harry B. Greenberg

×

Abstract

Nutrient excess, a major driver of obesity, diminishes hypothalamic responses to exogenously administered leptin, a critical hormone of energy balance. Here, we aimed to identify a physiological signal that arises from excess caloric intake and negatively controls hypothalamic leptin action. We found that deficiency of the gastric inhibitory polypeptide receptor (Gipr) for the gut-derived incretin hormone GIP protected against diet-induced neural leptin resistance. Furthermore, a centrally administered antibody that neutralizes GIPR had remarkable antiobesity effects in diet-induced obese mice, including reduced body weight and adiposity, and a decreased hypothalamic level of SOCS3, an inhibitor of leptin actions. In contrast, centrally administered GIP diminished hypothalamic sensitivity to leptin and increased hypothalamic levels of Socs3. Finally, we show that GIP increased the active form of the small GTPase Rap1 in the brain and that its activation was required for the central actions of GIP. Altogether, our results identify GIPR/Rap1 signaling in the brain as a molecular pathway linking overnutrition to the control of neural leptin actions.

Authors

Kentaro Kaneko, Yukiko Fu, Hsiao-Yun Lin, Elizabeth L. Cordonier, Qianxing Mo, Yong Gao, Ting Yao, Jacqueline Naylor, Victor Howard, Kenji Saito, Pingwen Xu, Siyu S. Chen, Miao-Hsueh Chen, Yong Xu, Kevin W. Williams, Peter Ravn, Makoto Fukuda

×

Abstract

Developing effective treatments for obesity and related metabolic disease remains a challenge. One logical strategy targets the appetite-regulating actions of gut hormones such as incretins. One of these incretins, glucose-dependent insulinotropic polypeptide (GIP), has garnered much attention as a potential target: however, whether it is beneficial to boost or block the action of GIP to promote weight loss remains an unresolved question. In this issue of the JCI, Kaneko and colleagues show that antagonizing GIP signaling in the CNS enhances the weight-reducing effects of leptin in rodents with diet-induced obesity. The authors posit that an increase in circulating intestinally derived GIP, as a consequence of overnutrition, acts in the brain to impair hypothalamic leptin action, resulting in increased food intake and body weight gain. This research advances the idea that multiple GIP signaling pathways and mechanisms exist in the obese state and offers intriguing new insights into the antiobesogenic consequences of antagonizing brain GIP action.

Authors

Jessica T.Y. Yue, Tony K.T. Lam

×

In-Press Preview - More

Abstract

Overexpression of myo-inositol oxygenase (MIOX), a proximal tubular enzyme, exacerbates cellular redox injury in acute kidney injury (AKI). Ferroptosis, a newly coined term associated with lipid hydroperoxidation, plays a critical role in the pathogenesis of AKI. Whether or not MIOX exacerbates tubular damage by accelerating ferroptosis in Cisplatin-induced AKI remains elusive. Cisplatin-treated HK-2 cells exhibited notable cell death, which was reduced by ferroptosis inhibitors. Also, alterations in various ferroptosis metabolic sensors, including lipid hydroperoxidation, glutathione peroxidase 4 (GPX4) activity, NADPH and reduced glutathione (GSH) levels, and ferritinophagy, were observed. These perturbations were accentuated by MIOX overexpression, while ameliorated by MIOX knockdown. Likewise, Cisplatin-treated CD1 mice exhibited tubular damage and derangement of renal physiological parameters, which was alleviated by Ferrostatin-1 (Fer-1), a ferroptosis inhibitor. To investigate the relevance of MIOX to ferroptosis, Wild-type (WT) mice, MIOX-overexpressing transgenic (MIOX-TG) mice and MIOX knockout (MIOX-KO) mice were subjected to Cisplatin treatment. In comparison to Cisplatin-treated WT mice, Cisplatin-treated MIOX-TG mice had more severe renal pathological changes and perturbations in ferroptosis metabolic sensors, which were minimal in Cisplatin-treated MIOX-KO mice. In conclusion, these findings indicate that ferroptosis, an integral process in the pathogenesis of Cisplatin-induced AKI, is modulated by the expression profile of MIOX.

Authors

Fei Deng, Isha Sharma, Yingbo Dai, Ming Yang, Yashpal S. Kanwar

×

Abstract

The interleukin-3 receptor alpha subunit, CD123, is expressed on many hematologic malignancies including acute myeloid leukemia (AML) and blastic plasmacytoid dendritic cell neoplasm (BPDCN). Tagraxofusp (SL-401) is a CD123-targeted therapy consisting of interleukin-3 fused to a truncated diphtheria toxin payload. Factors influencing response to tagraxofusp other than CD123 expression are largely unknown. We interrogated tagraxofusp resistance in patients and experimental models and found that it was not associated with CD123 loss. Rather, resistant AML and BPDCN cells frequently acquired deficiencies in the diphthamide synthesis pathway, impairing tagraxofusp’s ability to ADP-ribosylate cellular targets. Expression of DPH1, encoding a diphthamide pathway enzyme, was reduced by DNA CpG methylation in resistant cells. Treatment with the DNA methyltransferase inhibitor azacitidine restored DPH1 expression and tagraxofusp sensitivity. We also developed a drug-dependent ADP-ribosylation assay in primary cells that correlated with tagraxofusp activity and may represent an additional novel biomarker. As predicted by these results and our observation that resistance also increased mitochondrial apoptotic priming, we found that the combination of tagraxofusp and azacitidine was effective in patient-derived xenografts treated in vivo. These data have important implications for clinical use of tagraxofusp and led to a phase 1 study combining tagraxofusp and azacitidine in myeloid malignancies.

Authors

Katsuhiro Togami, Timothy Pastika, Jason Stephansky, Mahmoud Ghandi, Amanda L. Christie, Kristen L. Jones, Carl A. Johnson, Ross W. Lindsay, Christopher L. Brooks, Anthony Letai, Jeffrey W. Craig, Olga Pozdnyakova, David M. Weinstock, Joan Montero, Jon C. Aster, Cory M. Johannessen, Andrew A. Lane

×

Abstract

Asthma is a heterogeneous syndrome that has been subdivided into physiological phenotypes and molecular endotypes. The most specific phenotypic manifestation of asthma is indirect airway hyperresponsiveness (AHR), and a prominent molecular endotype is the presence of type-2 inflammation. The underlying basis for type-2 inflammation and its relationship to AHR are incompletely understood. We assessed the expression of type-2 cytokines in the airways of subjects with and without asthma who were extensively characterized for AHR. Using quantitative morphometry of the airway wall, we identified a shift in mast cells from the submucosa to the airway epithelium specifically associated with both type-2 inflammation and indirect AHR. Using ex vivo modeling of primary airway epithelial cells in organotypic co-culture with mast cells, we have shown that epithelial-derived IL-33 uniquely induced type-2 cytokines in mast cells, which regulated the expression of epithelial IL33 in a feedforward loop. This feedforward loop was accentuated in epithelial cells derived from subjects with asthma. These results demonstrate that type-2 inflammation and indirect AHR in asthma are related to a shift in mast cell infiltration to the airway epithelium, and that mast cells cooperate with epithelial cells through IL-33 signaling to regulate type-2 inflammation.

Authors

Matthew C. Altman, Ying Lai, James D. Nolin, Sydney Long, Chien-Chang Chen, Adrian M. Piliponsky, William A. Altemeier, Megan Larmore, Charles W. Frevert, Michael S. Mulligan, Steven F. Ziegler, Jason S. Debley, Michael C. Peters, Teal S. Hallstrand

×

Abstract

Patients with paroxysmal nocturnal hemoglobinuria (PNH) have a clonal population of blood cells deficient in glycosylphosphatidylinositol (GPI)-anchored proteins, resulting from a mutation in the X-linked gene PIGA. Here we report on a set of patients in whom PNH results instead from biallelic mutation of PIGT on chromosome 20. These PIGT-PNH patients have clinically typical PNH, but they have in addition prominent auto-inflammatory features, including recurrent attacks of aseptic meningitis. In all these patients we find a germ-line point mutation in one PIGT allele, whereas the other PIGT allele is removed by somatic deletion of a 20q region comprising maternally imprinted genes implicated in myeloproliferative syndromes. Unlike in PIGA-PNH cells, GPI is synthesized in PIGT-PNH cells and, since its attachment to proteins is blocked, free GPI is expressed on the cell surface. From studies of patients’ leukocytes and of PIGT-knockout THP-1 cells we show that, through increased IL-1β secretion, activation of the lectin pathway of complement and generation of C5b-9 complexes, free GPI is the agent of auto-inflammation. Eculizumab treatment abrogates not only intravascular hemolysis, but also auto-inflammation. Thus, PIGT-PNH differs from PIGA-PNH both in the mechanism of clonal expansion and in clinical manifestations.

Authors

Britta Höchsmann, Yoshiko Murakami, Makiko Osato, Alexej Knaus, Michi Kawamoto, Norimitsu Inoue, Tetsuya Hirata, Shogo Murata, Markus Anliker, Thomas Eggermann, Marten Jäger, Ricarda Floettmann, Alexander Höellein, Sho Murase, Yasutaka Ueda, Jun-ichi Nishimura, Yuzuru Kanakura, Nobuo Kohara, Hubert Schrezenmeier, Peter M. Krawitz, Taroh Kinoshita

×

Abstract

The parathyroid hormone receptor (PTH1R) mediates the biologic actions of parathyroid hormone (PTH) and parathyroid hormone related protein (PTHrP). Here, we showed that salt inducible kinases (SIKs) are key kinases that control the skeletal actions downstream of PTH1R and that this GPCR, when activated, inhibited cellular SIK activity. Sik gene deletion led to phenotypic changes that were remarkably similar to models of increased PTH1R signaling. In growth plate chondrocytes, PTHrP inhibited SIK3 and ablation of this kinase in proliferating chondrocytes rescued perinatal lethality of PTHrP-null mice. Combined deletion of Sik2/Sik3 in osteoblasts and osteocytes led to a dramatic increase in bone mass that closely resembled the skeletal and molecular phenotypes observed when these bone cells express a constitutively active PTH1R that causes Jansen’s metaphyseal chondrodysplasia. Finally, genetic evidence demonstrated that class IIa HDACs were key PTH1R-regulated SIK substrates in both chondrocytes and osteocytes. Taken together, our findings established that SIK inhibition is central to PTH1R action in bone development and remodeling. Furthermore, this work highlighted the key role of cAMP-regulated salt inducible kinases downstream of GPCR action.

Authors

Shigeki Nishimori, Maureen J. O'Meara, Christian Castro, Hiroshi Noda, Murat Cetinbas, Janaina da Silva Martins, Ugur Ayturk, Daniel J. Brooks, Michael Bruce, Mizuki Nagata, Wanida Ono, Christopher J. Janton, Mary L. Bouxsein, Marc Foretz, Rebecca Berdeaux, Ruslan I. Sadreyev, Thomas J. Gardella, Harald Jüppner, Henry M. Kronenberg, Marc N. Wein

×

Advertisement

August 2019

August 2019 Issue

On the cover:
Targeting mitochondrial cardiolipin in diabetic kidney disease

In this issue of the JCI, Ducasa et al. interrogated the role of the cholesterol and phospholipid transporter ABCA1 in podocyte injury in diabetic kidney disease (DKD), focusing on its contribution to aberrant mitochondrial metabolism. Whereas podocyte-specific ABCA1 deficiency increased mitochondrial cardiolipin and impaired oxidative phosphorylation, inducing ABCA1 expression or stabilizing cardiolipin reduced podocyte injury and improved DKD-like pathology in mouse models. Altogether, these insights reveal potential therapeutic targets for managing DKD progression. The cover image features a transmission electron microscopy image highlighting the presence of mitochondria in podocyte foot processes within the glomerular filtration barrier. Image credit: Hazel Szeto and Shaoyi Liu.

×

August 2019 JCI This Month

JCI This Month is a digest of the research, reviews, and other features published each month.

×

Review Series - More

Reparative Immunology

Series edited by Hamid Rabb and Franco R. D'Alessio

The immune system mounts a rapid inflammatory response to injury to mobilize cells and molecular pathways that promote hemostasis and prevent infection, but this acute response is only the first phase of recovery. Wound repair and inflammation-resolving processes are essential to recovering homeostasis in the aftermath of an injury: inefficient healing or prolonged inflammation can drive chronic dysfunction in the affected tissue. The Reparative Immunology series highlights the immune system’s contributions to these critical repair processes, from the roles of T cells, macrophages, neutrophils, and innate lymphoid cells in physiological repair to the influence of cytokine signaling, immunometabolism, and epigenetic reprogramming on pathological outcomes of injury. Together, these reviews emphasize the complexity of the immune environment in injured tissue and indicate numerous potential opportunities to intervene in dysfunctional wound-healing.

×