There has been great progress in ocular gene therapy, but delivery of viral vectors to the retinal pigmented epithelium (RPE) and retina can be challenging. Subretinal injection, the preferred route of delivery for most applications, requires a surgical procedure that has risks. Herein we report a novel gene therapy delivery approach, suprachoroidal injection of AAV8 vectors, which is less invasive and could be done in an outpatient setting. Two weeks after suprachoroidal injection of AAV8.GFP in rats, GFP fluorescence covered 18.9% of RPE flat mounts and extended entirely around sagittal and transverse sections in RPE and photoreceptors. After 2 suprachoroidal injections of AAV8.GFP, GFP fluorescence covered 30.5% of RPE flat mounts. Similarly, widespread expression of GFP occurred in nonhuman primate and pig eyes after suprachoroidal injection of AAV8.GFP. Compared with subretinal injection in rats of RGX-314, an AAV8 vector expressing an anti-VEGF Fab, suprachoroidal injection of the same dose of RGX-314 resulted in similar expression of anti-VEGF Fab and similar suppression of VEGF-induced vascular leakage. Suprachoroidal AAV8 vector injection provides a noninvasive outpatient procedure to obtain widespread transgene expression in retina and RPE.
Kun Ding, Jikui Shen, Zibran Hafiz, Sean F. Hackett, Raquel Lima e Silva, Mahmood Khan, Valeria E. Lorenc, Daiqin Chen, Rishi Chadha, Minie Zhang, Sherri Van Everen, Nicholas Buss, Michele Fiscella, Olivier Danos, Peter A. Campochiaro
Mutations affecting the integrity of the essential torsin ATPase/cofactor system have been identified in a steadily increasing number of congenital disorders. Since most of these mutations affect brain function, much of the research has focused on deciphering disease etiology in the brain. However, torsin is expressed in a wide variety of nonneural tissues and is strictly conserved across species, including the lowest metazoans, suggesting that it plays roles extending beyond neurons. In this issue of the JCI, Shin et al. explored torsin function in the mammalian liver. The group reports major defects in hepatic lipid metabolism when the torsin system is compromised in mice. Remarkably, conditional deletion of either torsinA or its cofactor, lamina-associated polypeptide 1 (LAP1), resulted in fatty liver disease and steatohepatitis, likely from a secretion defect of VLDLs. This study considerably expands our understanding of torsin biology, while providing defined opportunities for future investigations of torsin function and dysfunction in human pathologies.
Sarah M. Prophet, Christian Schlieker
Steven B. Abramson, Paul J. Anderson, Jill P. Buyon, Bruce N. Cronstein, Thoru Pederson, Mark R. Philips, Charles N. Serhan
BACKGROUND Spinal muscular atrophy (SMA) is caused by deficient expression of survival motor neuron (SMN) protein. New SMN-enhancing therapeutics are associated with variable clinical benefits. Limited knowledge of baseline and drug-induced SMN levels in disease-relevant tissues hinders efforts to optimize these treatments.METHODS SMN mRNA and protein levels were quantified in human tissues isolated during expedited autopsies.RESULTS SMN protein expression varied broadly among prenatal control spinal cord samples, but was restricted at relatively low levels in controls and SMA patients after 3 months of life. A 2.3-fold perinatal decrease in median SMN protein levels was not paralleled by comparable changes in SMN mRNA. In tissues isolated from nusinersen-treated SMA patients, antisense oligonucleotide (ASO) concentration and full-length (exon 7 including) SMN2 (SMN2-FL) mRNA level increases were highest in lumbar and thoracic spinal cord. An increased number of cells showed SMN immunolabeling in spinal cord of treated patients, but was not associated with an increase in whole-tissue SMN protein levels.CONCLUSIONS A normally occurring perinatal decrease in whole-tissue SMN protein levels supports efforts to initiate SMN-inducing therapies as soon after birth as possible. Limited ASO distribution to rostral spinal and brain regions in some patients likely limits clinical response of motor units in these regions for those patients. These results have important implications for optimizing treatment of SMA patients and warrant further investigations to enhance bioavailability of intrathecally administered ASOs.FUNDING SMA Foundation, SMART, NIH (R01-NS09677, R01-NS062269), Ionis Pharmaceuticals, and PTC Therapeutics. Biogen provided support for absolute real-time RT-PCR.
Daniel M. Ramos, Constantin d’Ydewalle, Vijayalakshmi Gabbeta, Amal Dakka, Stephanie K. Klein, Daniel A. Norris, John Matson, Shannon J. Taylor, Phillip G. Zaworski, Thomas W. Prior, Pamela J. Snyder, David Valdivia, Christine L. Hatem, Ian Waters, Nikhil Gupte, Kathryn J. Swoboda, Frank Rigo, C. Frank Bennett, Nikolai Naryshkin, Sergey Paushkin, Thomas O. Crawford, Charlotte J. Sumner
Deciphering novel pathways that regulate liver lipid content has profound implications for understanding the pathophysiology of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH). Recent evidence suggests that the nuclear envelope is a site of regulation of lipid metabolism, but there is limited appreciation of the responsible mechanisms and molecular components within this organelle. We showed that conditional hepatocyte deletion of the inner nuclear membrane protein lamina-associated polypeptide 1 (LAP1) causes defective VLDL secretion and steatosis, including intranuclear lipid accumulation. LAP1 binds to and activates torsinA, an AAA+ ATPase that resides in the perinuclear space and continuous main ER. Deletion of torsinA from mouse hepatocytes caused even greater reductions in VLDL secretion and profound steatosis. Mice from both of the mutant lines studied developed hepatic steatosis and subsequent steatohepatitis on a regular chow diet in the absence of whole-body insulin resistance or obesity. Our results establish an essential role for the nuclear envelope–localized torsinA-LAP1 complex in hepatic VLDL secretion and suggest that the torsinA pathway participates in the pathophysiology of NAFLD.
Ji-Yeon Shin, Antonio Hernandez-Ono, Tatyana Fedotova, Cecilia Östlund, Michael J. Lee, Sarah B. Gibeley, Chun-Chi Liang, William T. Dauer, Henry N. Ginsberg, Howard J. Worman
Fibronectin in the vascular wall promotes inflammatory activation of the endothelium during vascular remodeling and atherosclerosis. These effects are mediated in part by fibronectin binding to integrin α5, which recruits and activates phosphodiesterase 4D5 (PDE4D5) by inducing its dephosphorylation on an inhibitory site, S651. Active PDE then hydrolyzes antiinflammatory cAMP to facilitate inflammatory signaling. To test this model in vivo, we mutated the integrin binding site of PDE4D5 in mice. This mutation reduced endothelial inflammatory activation in atherosclerosis-prone regions of arteries and, in a hyperlipidemia model, reduced atherosclerotic plaque size while increasing markers of plaque stability. We then investigated the mechanism of PDE4D5 activation. Proteomics identified the PP2A regulatory subunit B55α as the factor recruiting PP2A to PDE4D5. The B55α-PP2A complex localized to adhesions and directly dephosphorylated PDE4D5. This interaction also, unexpectedly, stabilized the PP2A-B55α complex. The integrin-regulated, proatherosclerotic transcription factor Yap was also dephosphorylated and activated through this pathway. PDE4D5 therefore mediated matrix-specific regulation of endothelial cell phenotype via an unconventional adapter role, assembling and anchoring a multifunctional PP2A complex that has other targets. We believe these results may have widespread consequences for the control of cell function by integrins.
Sanguk Yun, Rui Hu, Melanie E. Schwaemmle, Alexander N. Scherer, Zhenwu Zhuang, Anthony J. Koleske, David C. Pallas, Martin A. Schwartz
The Toll-like receptor 8 (TLR8) has an important role in innate immune responses to RNA viral infections, including respiratory syncytial virus (RSV). We previously reported that TLR8 expression was increased directly by the tumor suppressor and transcription factor p53 via a single nucleotide polymorphism (SNP) (rs3761624) in the TLR8 promoter, thereby placing TLR8 in the p53/immune axis. Because this SNP is in linkage disequilibrium with other SNPs associated with several infectious diseases, we addressed the combined influence of p53 and the SNP on downstream inflammatory signaling in response to a TLR8 cognate ssRNA ligand. Using human primary lymphocytes, p53 induction by chemotherapeutic agents such as ionizing radiation caused SNP-dependent synergistic increases in IL-6 following incubation with an ssRNA ligand, as well as TLR8 RNA and protein expression along with p53 binding at the TLR-p53 SNP site. Because TLR8 is X-linked, the increases were generally reduced in heterozygous females. We found a corresponding association of the p53-responsive allele with RSV disease severity in infants hospitalized with RSV infection. We conclude that p53 can strongly influence TLR8-mediated immune responses and that knowledge of the p53-responsive SNP can inform diagnosis and prognosis of RSV disease and other diseases that might have a TLR8 component, including cancer.
Daniel Menendez, Joyce Snipe, Jacqui Marzec, Cynthia L. Innes, Fernando P. Polack, Mauricio T. Caballero, Shepherd H. Schurman, Steven R. Kleeberger, Michael A. Resnick
We report on 2 patients with compound heterozygous mutations in forkhead box N1 (FOXN1), a transcription factor essential for thymic epithelial cell (TEC) differentiation. TECs are critical for T cell development. Both patients had a presentation consistent with T–/loB+NK+ SCID, with normal hair and nails, distinct from the classic nude/SCID phenotype in individuals with autosomal-recessive FOXN1 mutations. To understand the basis of this phenotype and the effects of the mutations on FOXN1, we generated mice using CRISPR-Cas9 technology to genocopy mutations in 1 of the patients. The mice with the Foxn1 compound heterozygous mutations had thymic hypoplasia, causing a T–B+NK+ SCID phenotype, whereas the hair and nails of these mice were normal. Characterization of the functional changes due to the Foxn1 mutations revealed a 5–amino acid segment at the end of the DNA-binding domain essential for the development of TECs but not keratinocytes. The transcriptional activity of this Foxn1 mutant was partly retained, indicating a region that specifies TEC functions. Analysis of an additional 9 FOXN1 mutations identified in multiple unrelated patients revealed distinct functional consequences contingent on the impact of the mutation on the DNA-binding and transactivation domains of FOXN1.
Qiumei Du, Larry K. Huynh, Fatma Coskun, Erika Molina, Matthew A. King, Prithvi Raj, Shaheen Khan, Igor Dozmorov, Christine M. Seroogy, Christian A. Wysocki, Grace T. Padron, Tyler R. Yates, M. Louise Markert, M. Teresa de la Morena, Nicolai S.C. van Oers
The RV 144 HIV vaccine efficacy study showed a reduction in HIV-1 infection risk in Thai volunteers who received two priming vaccinations of vCP1521 ALVAC (attenuated recombinant canarypox virus expressing HIV group–specific antigen, polymerase, and envelope genes) followed by two additional ALVAC vaccinations and coadministration of purified bivalent gp120 proteins (AIDSVAX B/E). In this issue of the JCI, Rouphael et al. build on these results by substituting a DNA plasmid cocktail expressing HIV-1 subtype C group–specific antigen, polymerase, and envelope antigen genes (DNA-HIV-PT123) for ALVAC in a phase 1b safety and immunogenicity study. The results indicate that the vaccine regimen is safe, elicits promising cross-subtype humoral and cellular responses, and opens up potentially simplified approaches to HIV-1 vaccine development.
Nelson L. Michael
Two different antisense oligonucleotide–based (ASO-based) therapies are currently in clinical use to treat neuromuscular diseases. This success, for Duchenne muscular dystrophy and spinal muscular atrophy, offers hope not only for additional neuromuscular diseases, but also for other disorders that could benefit from RNA-targeted therapies. A major limitation for more widespread application of ASOs relates to relatively poor tissue penetration. In this issue of the JCI, Klein et al. showed that conjugating an ASO with an arginine-rich cell-penetrating peptide, Pip6a, enhanced delivery, resulting in corrective outcome for a mouse model of myotonic dystrophy. Linking ASOs to cell-penetrating peptides, or even other moieties, is an approach currently under development with treatment potential to expand to other disorders.
Elizabeth M. McNally, Brian D. Leverson
A vaccine for hepatitis C virus (HCV) is urgently needed. Development of broadly neutralizing plasma antibodies during acute infection is associated with HCV clearance, but the viral epitopes of these plasma antibodies are unknown. Identifying these epitopes could define the specificity and function of neutralizing antibodies (NAbs) that should be induced by a vaccine. Here, we present the development and application of a high-throughput method that deconvolutes polyclonal anti-HCV NAbs in plasma, delineating the epitope specificities of anti-HCV NAbs in acute-infection plasma of 44 humans with subsequent clearance or persistence of HCV. Remarkably, we identified multiple broadly neutralizing antibody combinations that were associated with greater plasma neutralizing breadth and with HCV clearance. These studies have the potential to inform new strategies for vaccine development by identifying broadly neutralizing antibody combinations in plasma associated with the natural clearance of HCV, while also providing a high-throughput assay that could identify these responses after vaccination trials.
Valerie J. Kinchen, Guido Massaccesi, Andrew I. Flyak, Madeleine C. Mankowski, Michelle D. Colbert, William O. Osburn, Stuart C. Ray, Andrea L. Cox, James E. Crowe Jr, Justin R. Bailey
Inflammatory bowel disease (IBD) is a chronic inflammatory disorder with rising incidence. Diseased tissues are heavily vascularized. Surprisingly, the pathogenic impact of the vasculature in IBD and the underlying regulatory mechanisms remain largely unknown. IFN-γ is a major cytokine in IBD pathogenesis, but in the context of the disease, it is almost exclusively its immune-modulatory and epithelial cell–directed functions that have been considered. Recent studies by our group demonstrated that IFN-γ also exerts potent effects on blood vessels. Based on these considerations, we analyzed the vessel-directed pathogenic functions of IFN-γ and found that it drives IBD pathogenesis through vascular barrier disruption. Specifically, we show that inhibition of the IFN-γ response in vessels by endothelial-specific knockout of IFN-γ receptor 2 ameliorates experimentally induced colitis in mice. IFN-γ acts pathogenic by causing a breakdown of the vascular barrier through disruption of the adherens junction protein VE-cadherin. Notably, intestinal vascular barrier dysfunction was also confirmed in human IBD patients, supporting the clinical relevance of our findings. Treatment with imatinib restored VE-cadherin/adherens junctions, inhibited vascular permeability, and significantly reduced colonic inflammation in experimental colitis. Our findings inaugurate the pathogenic impact of IFN-γ–mediated intestinal vessel activation in IBD and open new avenues for vascular-directed treatment of this disease.
Victoria Langer, Eugenia Vivi, Daniela Regensburger, Thomas H. Winkler, Maximilian J. Waldner, Timo Rath, Benjamin Schmid, Lisa Skottke, Somin Lee, Noo Li Jeon, Thomas Wohlfahrt, Viktoria Kramer, Philipp Tripal, Michael Schumann, Stephan Kersting, Claudia Handtrack, Carol I. Geppert, Karina Suchowski, Ralf H. Adams, Christoph Becker, Andreas Ramming, Elisabeth Naschberger, Nathalie Britzen-Laurent, Michael Stürzl
Antisense oligonucleotides (ASOs) targeting pathologic RNAs have shown promising therapeutic corrections for many genetic diseases including myotonic dystrophy (DM1). Thus, ASO strategies for DM1 can abolish the toxic RNA gain-of-function mechanism caused by nucleus-retained mutant DMPK (DM1 protein kinase) transcripts containing CUG expansions (CUGexps). However, systemic use of ASOs for this muscular disease remains challenging due to poor drug distribution to skeletal muscle. To overcome this limitation, we test an arginine-rich Pip6a cell-penetrating peptide and show that Pip6a-conjugated morpholino phosphorodiamidate oligomer (PMO) dramatically enhanced ASO delivery into striated muscles of DM1 mice following systemic administration in comparison with unconjugated PMO and other ASO strategies. Thus, low-dose treatment with Pip6a-PMO-CAG targeting pathologic expansions is sufficient to reverse both splicing defects and myotonia in DM1 mice and normalizes the overall disease transcriptome. Moreover, treated DM1 patient–derived muscle cells showed that Pip6a-PMO-CAG specifically targets mutant CUGexp-DMPK transcripts to abrogate the detrimental sequestration of MBNL1 splicing factor by nuclear RNA foci and consequently MBNL1 functional loss, responsible for splicing defects and muscle dysfunction. Our results demonstrate that Pip6a-PMO-CAG induces long-lasting correction with high efficacy of DM1-associated phenotypes at both molecular and functional levels, and strongly support the use of advanced peptide conjugates for systemic corrective therapy in DM1.
Arnaud F. Klein, Miguel A. Varela, Ludovic Arandel, Ashling Holland, Naira Naouar, Andrey Arzumanov, David Seoane, Lucile Revillod, Guillaume Bassez, Arnaud Ferry, Dominic Jauvin, Genevieve Gourdon, Jack Puymirat, Michael J. Gait, Denis Furling, Matthew J.A. Wood
BACKGROUND RV144 is the only preventive HIV vaccine regimen demonstrating efficacy in humans. Attempting to build upon RV144 immune responses, we conducted a phase 1, multicenter, randomized, double-blind trial to assess the safety and immunogenicity of regimens substituting the DNA-HIV-PT123 (DNA) vaccine for ALVAC-HIV in different sequences or combinations with AIDSVAX B/E (protein).METHODS One hundred and four HIV-uninfected participants were randomized to 4 treatment groups (T1, T2, T3, and T4) and received intramuscular injections at 0, 1, 3, and 6 months (M): T1 received protein at M0 and M1 and DNA at M3 and M6; T2 received DNA at M0 and M1 and protein at M3 and M6; T3 received DNA at M0, M1, M3, and M6 with protein coadministered at M3 and M6; and T4 received protein and DNA coadministered at each vaccination visit.RESULTS All regimens were well tolerated. Antibodies binding to gp120 and V1V2 scaffold were observed in 95%–100% of participants in T3 and T4, two weeks after final vaccination at high magnitude. While IgG3 responses were highest in T3, a lower IgA/IgG ratio was observed in T4. Binding antibodies persisted at 12 months in 35%–100% of participants. Antibody-dependent cell-mediated cytotoxicity and tier 1 neutralizing-antibody responses had higher response rates for T3 and T4, respectively. CD4+ T cell responses were detectable in all treatment groups (32%–64%) without appreciable CD8+ T cell responses.CONCLUSION The DNA/protein combination regimens induced high-magnitude and long-lasting HIV V1V2–binding antibody responses, and early coadministration of the 2 vaccines led to a more rapid induction of these potentially protective responses.TRIAL REGISTRATION ClinicalTrials.gov NCT02207920.FUNDING National Institute of Allergy and Infectious Diseases (NIAID) grants UM1 AI068614, UM1 AI068635, UM1 AI068618, UM1 AI069511, UM1 AI069470, UM1 AI069534, P30 AI450008, UM1 AI069439, UM1 AI069481, and UM1 AI069496; the National Center for Advancing Translational Sciences, NIH (grant UL1TR001873); and the Bill & Melinda Gates Foundation (grant OPP52845).
Nadine G. Rouphael, Cecilia Morgan, Shuying S. Li, Ryan Jensen, Brittany Sanchez, Shelly Karuna, Edith Swann, Magdalena E. Sobieszczyk, Ian Frank, Gregory J. Wilson, Hong-Van Tieu, Janine Maenza, Aliza Norwood, James Kobie, Faruk Sinangil, Giuseppe Pantaleo, Song Ding, M. Juliana McElrath, Stephen C. De Rosa, David C. Montefiori, Guido Ferrari, Georgia D. Tomaras, Michael C. Keefer, the HVTN 105 Protocol Team and the NIAID HIV Vaccine Trials Network
Lona Mody, Joel D. Howell, Sanjay Saint
Multiple sclerosis (MS) is a disabling disease of the CNS. Inflammatory features of MS include lymphocyte accumulations in the CNS and cerebrospinal fluid (CSF). The preclinical events leading to established MS are still enigmatic. Here we compared gene expression patterns of CSF cells from MS-discordant monozygotic twin pairs. Six “healthy” co-twins, who carry a maximal familial risk for developing MS, showed subclinical neuroinflammation (SCNI) with small MRI lesions. Four of these subjects had oligoclonal bands (OCBs). By single-cell RNA sequencing of 2752 CSF cells, we identified clonally expanded CD8+ T cells, plasmablasts, and, to a lesser extent, CD4+ T cells not only from MS patients but also from subjects with SCNI. In contrast to nonexpanded T cells, clonally expanded T cells showed characteristics of activated tissue-resident memory T (TRM) cells. The TRM-like phenotype was detectable already in cells from SCNI subjects but more pronounced in cells from patients with definite MS. Expanded plasmablast clones were detected only in MS and SCNI subjects with OCBs. Our data provide evidence for very early concomitant activation of 3 components of the adaptive immune system in MS, with a notable contribution of clonally expanded TRM-like CD8+ cells.
Eduardo Beltrán, Lisa Ann Gerdes, Julia Hansen, Andrea Flierl-Hecht, Stefan Krebs, Helmut Blum, Birgit Ertl-Wagner, Frederik Barkhof, Tania Kümpfel, Reinhard Hohlfeld, Klaus Dornmair
Histone H3K27 demethylase JMJD3 plays a critical role in gene expression and T cell differentiation. However, the role and mechanisms of JMJD3 in T cell trafficking remain poorly understood. Here, we show that JMJD3 deficiency in CD4+ T cells resulted in an accumulation of T cells in the thymus and reduction of T cell number in the secondary lymphoid organs. We identified PDLIM4 as a significantly downregulated target gene in JMJD3-deficient CD4+ T cells by gene profiling and ChIP-Seq analyses. We further showed that PDLIM4 functioned as an adaptor protein to interact with sphingosine-1 phosphate receptor 1 (S1P1) and filamentous actin (F-actin), thus serving as a key regulator of T cell trafficking. Mechanistically, JMJD3 bound to the promoter and gene-body regions of the Pdlim4 gene and regulated its expression by interacting with zinc finger transcription factor KLF2. Our findings have identified Pdlim4 as a JMJD3 target gene that affects T cell trafficking by cooperating with S1P1 and have provided insights into the molecular mechanisms by which JMJD3 regulates genes involved in T cell trafficking.
Chuntang Fu, Qingtian Li, Jia Zou, Changsheng Xing, Mei Luo, Bingnan Yin, Junjun Chu, Jiaming Yu, Xin Liu, Helen Y. Wang, Rong-Fu Wang
Cancer-associated mutations in the spliceosome gene SF3B1 create a neomorphic protein that produces aberrant mRNA splicing in hundreds of genes, but the ensuing biologic and therapeutic consequences of this missplicing are not well understood. Here we have provided evidence that aberrant splicing by mutant SF3B1 altered the transcriptome, proteome, and metabolome of human cells, leading to missplicing-associated downregulation of metabolic genes, decreased mitochondrial respiration, and suppression of the serine synthesis pathway. We also found that mutant SF3B1 induces vulnerability to deprivation of the nonessential amino acid serine, which was mediated by missplicing-associated downregulation of the serine synthesis pathway enzyme PHGDH. This vulnerability was manifest both in vitro and in vivo, as dietary restriction of serine and glycine in mice was able to inhibit the growth of SF3B1MUT xenografts. These findings describe a role for SF3B1 mutations in altered energy metabolism, and they offer a new therapeutic strategy against SF3B1MUT cancers.
W. Brian Dalton, Eric Helmenstine, Noel Walsh, Lukasz P. Gondek, Dhanashree S. Kelkar, Abigail Read, Rachael Natrajan, Eric S. Christenson, Barbara Roman, Samarjit Das, Liang Zhao, Robert D. Leone, Daniel Shinn, Taylor Groginski, Anil K. Madugundu, Arun Patil, Daniel J. Zabransky, Arielle Medford, Justin Lee, Alex J. Cole, Marc Rosen, Maya Thakar, Alexander Ambinder, Joshua Donaldson, Amy E. DeZern, Karen Cravero, David Chu, Rafael Madero-Marroquin, Akhilesh Pandey, Paula J. Hurley, Josh Lauring, Ben Ho Park
Fasting requires complex endocrine and metabolic interorgan crosstalk, which involves shifting from glucose to fatty acid oxidation, derived from adipose tissue lipolysis, in order to preserve glucose for the brain. The glucose-alanine (Cahill) cycle is critical for regenerating glucose. In this issue of JCI, Petersen et al. report on their use of an innovative stable isotope tracer method to show that skeletal muscle–derived alanine becomes rate controlling for hepatic mitochondrial oxidation and, in turn, for glucose production during prolonged fasting. These results provide new insight into skeletal muscle–liver metabolic crosstalk during the fed-to-fasting transition in humans.
Theresia Sarabhai, Michael Roden
Cancer-associated fibroblasts (CAFs) are key actors in modulating the progression of many solid tumors, such as breast cancer (BC). Herein, we identify an integrin α11/PDGFRβ–positive CAF subset displaying tumor-promoting features in BC. In the preclinical MMTV-PyMT mouse model, integrin α11 deficiency led to a drastic reduction of tumor progression and metastasis. A clear association between integrin α11 and PDGFRβ was found at both transcriptional and histological levels in BC specimens. High stromal integrin α11/PDGFRβ expression was associated with high grades and poorer clinical outcome in human BC patients. Functional assays using 5 CAF subpopulations (1 murine, 4 human) revealed that integrin α11 promotes CAF invasion and CAF-induced tumor cell invasion upon PDGF-BB stimulation. Mechanistically, the proinvasive activity of integrin α11 relies on its ability to interact with PDGFRβ in a ligand-dependent manner and to promote its downstream JNK activation, leading to the production of tenascin C, a proinvasive matricellular protein. Pharmacological inhibition of PDGFRβ and JNK impaired tumor cell invasion induced by integrin α11+ CAFs. Collectively, our study uncovers an integrin α11+ subset of protumoral CAFs that exploits the PDGFRβ/JNK signaling axis to promote tumor invasiveness in BC.
Irina Primac, Erik Maquoi, Silvia Blacher, Ritva Heljasvaara, Jan Van Deun, Hilde Y.H. Smeland, Annalisa Canale, Thomas Louis, Linda Stuhr, Nor Eddine Sounni, Didier Cataldo, Taina Pihlajaniemi, Christel Pequeux, Olivier De Wever, Donald Gullberg, Agnès Noel