The transcription factor interferon regulatory factor 5 (IRF5) is a central mediator of innate and adaptive immunity. Genetic variations within IRF5 associate with risk of systemic lupus erythematosus (SLE) and mice lacking Irf5 are protected from lupus onset and severity, but how IRF5 functions in the context of SLE disease progression remains unclear. Using the NZB/W F1 model of murine lupus, we show that murine Irf5 becomes hyper-activated before clinical onset. In SLE patients, IRF5 hyper-activation correlated with dsDNA titers. To test whether IRF5 hyper-activation is a targetable function, we developed novel inhibitors that are cell permeable, non-toxic and selectively bind to the inactive IRF5 monomer. Preclinical treatment of NZB/W F1 mice with inhibitor attenuated lupus pathology by reducing serum ANA, dsDNA titers and the number of circulating plasma cells, which alleviated kidney pathology and improved survival. Clinical treatment of MRL/lpr and pristane-induced mice with inhibitor led to significant reductions in dsDNA levels and improved survival. In ex vivo human studies, the inhibitor blocked SLE serum-induced IRF5 activation in healthy immune cells and reversed basal IRF5 hyper-activation in SLE immune cells. Altogether, this study provides the first in vivo clinical support for treating SLE patients with an IRF5 inhibitor.
Su Song, Saurav De, Victoria Nelson, Samin Chopra, Margaret LaPan, Kyle Kampta, Shan Sun, Mingzhu He, Cherrie D. Thompson, Dan Li, Tiffany Shih, Natalie Tan, Yousef Al-Abed, Eugenio Capitle, Cynthia Aranow, Meggan Mackay, William L. Clapp, Betsy J. Barnes
Pulmonary hypertension (PH) is characterized by pulmonary artery remodeling that can subsequently culminate in right heart failure and premature death. Emerging evidence suggests that Hypoxia Inducible Factor (HIF) signaling plays a fundamental and pivotal role in the pathogenesis of PH. This review summarizes the regulation of HIF isoforms and their impact in various PH subtypes, as well as the elaborate conditional and cell specific knockout mouse studies that brought the role of this pathway to light. We also discuss the current preclinical status of pan- and isoform-selective HIF inhibitors, and propose new research areas that may facilitate HIF isoform-specific inhibition as a novel therapeutic strategy for PH and right heart failure.
Soni Savai Pullamsetti, Argen Mamazhakypov, Norbert Weissmann, Werner Seeger, Rajkumar Savai
Epithelial cell dysfunction has emerged as a central component in the pathophysiology of diffuse parenchymal diseases including idiopathic pulmonary fibrosis (IPF). Alveolar type 2 (AT2) cells represent a metabolically active lung cell population important for surfactant biosynthesis and alveolar homeostasis. AT2 cells and other distal lung epithelia, like all eukaryotic cells, contain an elegant quality control (QC) network to respond to intrinsic metabolic and biosynthetic challenges imparted by mutant protein conformers, dysfunctional subcellular organelles, and dysregulated telomeres. Failed AT2 QC components (ubiquitin-proteasome system, unfolded protein response, macroautophagy, mitophagy, and telomere maintenance) result in diverse cellular endophenotypes and molecular signatures including ER stress, defective autophagy, mitochondrial dysfunction, apoptosis, inflammatory cell recruitment, profibrotic signaling, and altered progenitor function that ultimately converge to drive downstream fibrotic remodeling in the IPF lung. As this complex network becomes increasingly better understood, opportunities will emerge to identify targets and therapeutic strategies for IPF.
Jeremy Katzen, Michael F. Beers
Hypoxia-inducible factors (HIFs) and the HIF-dependent cancer hallmarks angiogenesis and metabolic rewiring are well-established drivers of breast cancer aggressiveness, therapy resistance, and poor prognosis. Targeting of HIF and its downstream targets in angiogenesis and metabolism has been unsuccessful so far in the breast cancer clinical setting, with major unresolved challenges residing in target selection, development of robust biomarkers for response prediction, and understanding and harnessing escape mechanisms. This Review discusses the pathophysiological role of HIFs, angiogenesis, and metabolism in breast cancer and the challenges of targeting these features in breast cancer patients. Rational therapeutic combinations, especially with immunotherapy and endocrine therapy, seem most promising in the clinical exploitation of the intricate interplay of HIFs, angiogenesis, and metabolism in breast cancer cells and the tumor microenvironment.
Ellen C. de Heer, Mathilde Jalving, Adrian L. Harris
Hypoxia/HIF-1α- and extracellular adenosine/A2-adenosine receptor-mediated immunosuppression protects tissues from collateral damage by anti-pathogen immune cells. However, this mechanism also protects cancerous tissues by inhibiting anti-tumor immune cells in hypoxic and extracellular adenosine-rich tumors that are the most resistant to current therapies. Here, we explain a conceptually novel, anti-immunosuppressive reasoning to justify strategies using respiratory hyperoxia and oxygenation agents in cancer treatment. Earlier attempts to use oxygenation of tumors as a monotherapy or to improve radiotherapy have failed because oxygenation protocols were not combined with immunotherapies of cancer. In contrast, the proposal for therapeutic use of anti-hypoxic oxygenation described here was motivated by the need to prevent the hypoxia/HIF-1α-driven accumulation of extracellular adenosine to (i) unleash anti-tumor immune cells from inhibition by intracellular cAMP and (ii) prevent immunosuppressive transcription of cAMP response element- and hypoxia response element-containing immunosuppressive gene products (e.g. TGF-β. Using oxygenation agents together with inhibitors of the A2A adenosine receptor may be required to enable the most effective cancer immunotherapy. The emerging outcomes from clinical trials of cancer patients refractory to all other treatments provide support for the molecular and immunological mechanism-based approach to cancer immunotherapy described here.
Stephen M. Hatfield, Michail V. Sitkovsky
Several important features of Multisystem Inflammatory Syndrome in Children (MIS-C) differentiate it from Kawasaki disease. Rowley et al. discuss what is known about MIS-C and the need to elucidate the specific immune mechanisms underlying hyperinflammatory syndromes caused by SARS-CoV-2 to advance potential targeted treatments and prevention efforts.
Anne H. Rowley, Stanford T. Shulman, Moshe Arditi
The sodium-phosphate co-transporter NPT2a plays a key role in reabsorbing filtered phosphate in proximal renal tubules thereby critically contributing to phosphate homeostasis. Inadequate urinary phosphate excretion can lead to severe hyperphosphatemia as in tumoral calcinosis, and in chronic kidney disease (CKD). Pharmacological inhibition of NPT2a may therefore represent a novel approach for treating hyperphosphatemic conditions. The NPT2a-selective small molecule inhibitor, PF-06869206, was previously shown to reduce phosphate uptake in human proximal tubular cells in vitro. We now investigated the acute and chronic effects of the inhibitor in vivo and report that administration of PF-06869206 was well-tolerated and elicited a dose-dependent increase in fractional phosphate excretion. This phosphaturic effect lowered plasma phosphate levels in wild-type mice and in rats with CKD due to subtotal nephrectomy. PF-06869206 had no effect in Npt2a-null mice, but promoted phosphate excretion and reduced plasma phosphate in normophophatemic mice lacking Npt2c and in hyperphosphatemic mice lacking Fgf23 or Galnt3. In CKD rats, once daily administration of PF-06869206 for eight weeks induced an unabated acute phosphaturic and hypophosphatemic effect, but had no significant effect on FGF23 or PTH levels. Selective pharmacological inhibition of NPT2a thus holds promises as a novel therapeutic option for genetic and acquired hyperphosphatemic disorders.
Valerie Clerin, Hiroshi Saito, Kevin J. Filipski, An Hai Nguyen, Jeonifer Garren, Janka Kisucka, Monica Reyes, Harald Jüppner
Astrocytes play multiple functions in the brain, including blood vessel (BV) homeostasis and function. However, the underlying mechanisms remain elusive. Here, we provide evidence for astrocytic neogenin (NEO1), a member of deleted in colorectal cancer (DCC) family netrin receptors, to be involved in this event. Mice with Neo1 depletion in astrocytes exhibited clustered astrocyte distribution and increased BVs in their cortex. These BVs were leaky with reduced blood flow, disrupted basement membranes (vBMs), decreased pericytes, impaired endothelial cell (EC) barrier, and elevated tip EC proliferation. Increased proliferation was also detected in cultured ECs exposed to the conditional medium (CM) of NEO1 depleted astrocytes. Further screening for angiogenetic factors in the CM identifies netrin-1 (NTN1), whose expression was decreased in NEO1 depleted cortical astrocytes. Adding NTN1 into the CM of NEO1 depleted astrocytes attenuated EC proliferation. Expressing NTN1 in NEO1 mutant cortical astrocytes ameliorated phenotypes in blood–brain barrier (BBB), EC, and astrocyte distribution. NTN1 depletion in astrocytes resulted in similar BV/BBB deficits in the cortex as those of Neo1 mutant mice. In aggregates, these results uncovered an unrecognized pathway, astrocytic NEO1 to NTN1, not only regulating astrocyte distribution, but also promoting cortical BV homeostasis and function.
Ling-ling Yao, Jin-xia Hu, Qiang Li, Daehoon Lee, Xiao Ren, Jun-shi Zhang, Dong Sun, Hong-sheng Zhang, Yong-gang Wang, Lin Mei, Wen-Cheng Xiong
After over three decades of research, an effective anti-HIV vaccine remains elusive. The recently halted HVTN702 clinical trial not only further stresses the challenge to develop an effective HIV vaccine, but also emphasizes that unconventional and novel vaccine strategies are urgently needed. Here, we report that a vaccine focusing the immune response on the sequences surrounding the 12 viral protease cleavage sites (PCSs) provided greater than 80% protection to Mauritian cynomolgus macaques (MCMs) against repeated intravaginal SIVmac251 challenges. The PCS-specific T cell responses correlated with vaccine efficacy. The PCS vaccine did not induce immune activation or inflammation known to be associated with increased susceptibility to HIV infection. Machine learning analyses revealed that the immune microenvironment generated by the PCS vaccine was predictive of vaccine efficacy. Our study demonstrates for the first time that a vaccine which targets only viral maturation, but lacks full-length Env and Gag immunogens, can prevent intravaginal infection in a stringent macaque/SIV challenge model. Targeting HIV maturation thus offers a novel approach to developing an effective HIV vaccine.
Hongzhao Li, Robert W. Omange, Binhua Liang, Nikki Toledo, Yan Hai, Lewis R. Liu, Dane Schalk, Jose Crecente-Campo, Tamara G. Dacoba, Andrew B. Lambe, So-Yon Lim, Lin Li, Mohammad Abul Kashem, Yanmin Wan, Jorge F. Correia-Pinto, Michael S. Seaman, Xiao-Qing Liu, Robert F. Balshaw, Qingsheng Li, Nancy Schultz-Darken, Maria Jose Alonso, Francis A. Plummer, James B. Whitney, Ma Luo
Heterotopic ossification (HO) is pathological bone formation characterized by ossification within muscle, tendons, or other soft tissues. However, the cells of origin and mechanisms involved in the pathogenesis of HO remain elusive. Here we show that deletion of Suppressor of fused (Sufu) in Cathepsin K-Cre-expressing (Ctsk-Cre-expressing) cells resulted in spontaneous and progressive ligament, tendon, and periarticular ossification. Lineage tracing studies and cell functional analysis demonstrated that Ctsk-Cre could label a subpopulation of tendon-derived progenitor cells (TDPCs) marked by tendon marker Scleraxis (Scx). Ctsk+Scx+ TDPCs are enriched for tendon stem cell markers and show the highest self-renewal capacity and differentiation potential. Sufu deficiency caused enhanced chondrogenic and osteogenic differentiation of Ctsk-Cre-expressing tendon-derived cells via upregulating Hedgehog (Hh) signaling. Furthermore, pharmacological intervention of hedgehog signaling using JQ1 suppressed the development of HO. Thus, our results display that Cathepsin K-Cre labels a subpopulation of TDPCs contributing to HO and their cell fate changes are driven by activation of Hh signaling.
Heng Feng, Wenhui Xing, Yujiao Han, Jun Sun, Mingxiang Kong, Bo Gao, Yang Yang, Zi Yin, Xiao Chen, Yun Zhao, Qing Bi, Weiguo Zou
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