Epstein-Barr virus-induced gene 3 (EBI3) is a subunit common to IL-27, IL-35, and IL-39. Here, we explore an intracellular role of EBI3 independent of function as cytokines. EBI3-deficient naive CD4+ T cells had reduced IFN-γ production and failed to induce T cell-dependent colitis in mice. Similarly reduced IFN-γ production was observed in vitro in EBI3-deficient CD4+ T cells differentiated under pathogenic Th17 polarizing conditions with IL-23. This is because the induction of expression of one of IL-23 receptor (R) subunits, IL-23Rα, but not another IL-23R subunit, IL-12Rβ1, was selectively decreased at the protein level but not the mRNA level. EBI3 augmented IL-23Rα expression via binding to the chaperone molecule calnexin and to IL-23Rα in a peptide-dependent manner, but not glycan-dependent manner. Indeed, EBI3 failed to augment the IL-23Rα expression in the absence of endogenous calnexin. Moreover, EBI3 poorly augmented the expression of G149R, an IL-23Rα variant that protects against the development of human colitis, because binding of EBI3 to the variant was reduced. Taking together with the result that EBI3 expression is inducible in T cells, the present results suggest that EBI3 plays a critical role in augmenting IL-23Rα protein expression via calnexin under inflammatory conditions.
Izuru Mizoguchi, Mio Ohashi, Hideaki Hasegawa, Yukino Chiba, Naoko Orii, Shinya Inoue, Chiaki Kawana, Mingli Xu, Katsuko Sudo, Koji Fujita, Masahiko Kuroda, Shin-ichi Hashimoto, Kouji Matsushima, Takayuki Yoshimoto
Background:While mitochondria play an important role in innate immunity, the relationship between mitochondrial dysfunction and inflammation in heart failure (HF) is poorly understood. In this study we aimed to investigate the mechanistic link between mitochondrial dysfunction and inflammatory activation in peripheral blood mononuclear cells (PBMCs), and the potential anti-inflammatory effect of boosting NAD level.Methods:We compared the PBMC mitochondrial respiration of 19 hospitalized Stage D HF patients with 19 healthy participants. We then created an in vitro model of sterile inflammation by treating healthy PBMC with MitoDAMP (Mitochondrial Damage-Associated Molecular Patterns) isolated from human heart tissue. Lastly, we enrolled Stage D HF patients and sampled their blood before and after taking 5-9 days of oral nicotinamide riboside, an NAD precursor.Results:We demonstrated that HF is associated with both reduced respiratory capacity and elevated proinflammatory cytokine gene expressions. In our in vitro model, MitoDAMP-treated PBMCs secreted IL-6 that impaired mitochondrial respiration by reducing Complex I activity. Last, oral NR administration enhanced PBMC respiration and reduced proinflammatory cytokine gene expression in 4 HF subjects.Conclusion:These findings suggest that systemic inflammation in HF patients is causally linked to mitochondrial function of the PBMC. Increasing NAD levels may have the potential to improve mitochondrial respiration and attenuate proinflammatory activation of PBMC in HF. FundingThis study is funded by NIH R21 HL126209 (to RT and KO), NIH R01 HL144937 (to KO and RT) and University of Washington ITHS Catalyst Award (to DDW). Both BZ (18POST33990352) and DDW (18POST34030098) are funded by the AHA Postdoctoral Fellowships.
Bo Zhou, Dennis D. Wang, Yanhua Qiu, Sophia Airhart, Yaxin Liu, April Stempien-Otero, Kevin D. O’Brien, Rong Tian.
Mitochondria have emerged as key actors of innate and adaptive immunity. Mitophagy has a pivotal role in cell homeostasis but its contribution to macrophage functions and host defense remains to be delineated. Here we showed that lipopolysaccharide (LPS) in combination with IFNγ, inhibits PINK1-dependent mitophagy in macrophages through a STAT1-dependent activation of the inflammatory caspases 1 and 11. In addition, we demonstrated that the inhibition of mitophagy triggers classical macrophage activation in a mitochondrial ROS-dependent manner. In a murine model of polymicrobial infection (cecal ligature and puncture, CLP), adoptive transfer of Pink1-deficient bone marrow or pharmacological inhibition of mitophagy promoted macrophage activation which favored bactericidal clearance and lead to a better survival. Reciprocally, mitochondrial uncouplers, that promote mitophagy, reverse LPS/IFNγ-mediated activation of macrophages and lead to immuno-paralysis with impaired bacterial clearance and lowered survival. In critically ill patients, we showed that mitophagy is inhibited in blood monocytes of patients with sepsis as compared to non-septic patients. Overall, this work demonstrates that the inhibition of mitophagy is a physiological mechanism that contributes to the activation of myeloid cells and improves the outcome of sepsis.
Danish Patoli, Franck Mignotte, Valérie Deckert, Alois Dusuel, Adelie Dumont, Aurelie Rieu, Antoine Jalil, Kevin Van Dongen, Thibaut Bourgeois, Thomas Gautier, Charlene Magnani, Naig Le Guern, Stéphane Mandard, Jean Bastin, Fatima Djouadi, Christine Schaeffer, Nina Guillaumot, Michel Narce, Maxime Nguyen, Julien Guy, Auguste Dargent, Jean-Pierre Quenot, Mickaël Rialland, David Masson, Johan Auwerx, Laurent Lagrost, Charles Thomas
Although IKK-β has previously been shown as a negative regulator of IL-1β secretion in mice, this role has not been demonstrated in humans. Genetic studies of NF-κB signalling in humans with inherited diseases of the immune system have not demonstrated the relevance of the NF-κB pathway in suppression of IL-1β expression. Here, we report an infant displaying clinical pathology comprising neutrophil-mediated auto-inflammation and recurrent bacterial infections. Whole-exome sequencing revealed a de novo heterozygous missense mutation in NFKBIA, resulting in a L34P IκBα variant, that severely repressed NF-κB activation and downstream cytokine production. Paradoxically, IL-1β secretion was elevated in the patient’s stimulated leukocytes, in her induced-pluripotent stem cell-derived macrophages, and in murine bone marrow-derived macrophages containing the L34P mutation. The patient’s hyper-IL-1β secretion correlated with activated neutrophilia and liver fibrosis with neutrophil accumulation. Hematopoietic stem cell transplantation reversed neutrophilia, restored a resting state in neutrophils, and normalized IL-1β release from stimulated leukocytes. Additional therapeutic blockade of IL-1 ameliorated liver damage, whilst decreasing neutrophil activation and associated IL-1β secretion. Our studies reveal a previously unrecognized role of human IκBα as an essential regulator of canonical NF-κB signalling in the prevention of neutrophilic-dependent auto-inflammatory diseases. We showed that IκBα controls IL-1β secretion through a mechanism of self-limiting post-transcriptional regulation. These findings also highlight a therapeutic potential for IL-1 inhibitors to treat complications arising from systemic NF-κB inhibition.
Enrica Ee Kar Tan, Richard Hopkins, Chrissie K. Lim, Saumya Jamuar, Christina Ong, Koh Cheng Thoon, Mark J.A. Koh, Eun Myoung Shin, Derrick Wen Quan Lian, Madhushanee Weerasooriya, Christopher Z.W Lee, Andreas Alvin Purnomo Soetedjo, Chang Siang Lim, Veronica B. Au, WM Edmond Chua, Hui Yin Lee, Leigh Ann Jones, Sharmy Jennifer James, Nivashini Kaliaperumal, Jeffrey Kwok, Ee Shien Tan, Biju Thomas, Lena Ho, Lynn Wu, Anna-Marie Fairhurst, Florent Ginhoux, Adrian K.K. Teo, Yongliang Zhang, Kok Haur Ong, Weimiao Yu, Byrappa Venkatesh, Vinay Tergaonkar, Bruno Reversade, Keh-Chuang Chin, Ah Moy Tan, Woei Kang Liew, John E. Connolly
Exposure of mononuclear phagocytes to β-glucan, a naturally occurring polysaccharide, contributes to the induction of innate immune memory, which is associated with long-term epigenetic, metabolic, and functional reprogramming. Although previous studies have shown that innate immune memory induced by β-glucan confers protection against secondary infections, its impact on autoinflammatory diseases, associated with inflammasome activation and IL-1β secretion, remains poorly understood. In particular, whether β-glucan–induced long-term reprogramming affects inflammasome activation in human macrophages in the context of these diseases has not been explored. We found that NLRP3 inflammasome–mediated caspase-1 activation and subsequent IL-1β production were reduced in β-glucan–reprogrammed macrophages. β-Glucan acted upstream of the NLRP3 inflammasome by preventing potassium (K+) efflux, mitochondrial ROS (mtROS) generation, and, ultimately, apoptosis-associated speck-like protein containing a CARD (ASC) oligomerization and speck formation. Importantly, β-glucan–induced memory in macrophages resulted in a remarkable attenuation of IL-1β secretion and caspase-1 activation in patients with an NLRP3-associated autoinflammatory disease, cryopyrin-associated periodic syndromes (CAPS). Our findings demonstrate that β-glucan–induced innate immune memory represses IL-1β–mediated inflammation and support its potential clinical use in NLRP3-driven diseases.
Giorgio Camilli, Mathieu Bohm, Alícia Corbellini Piffer, Rachel Lavenir, David L. Williams, Benedicte Neven, Gilles Grateau, Sophie Georgin-Lavialle, Jessica Quintin
Pathologic lymphatic remodeling in lymphedema evolves during periods of tissue inflammation and hypoxia through poorly defined processes. In human and mouse lymphedema, there is a significant increase of hypoxia inducible factor (HIF)-1α, but a reduction of HIF-2α protein expression in lymphatic endothelial cells (LECs). We questioned whether dysregulated expression of these transcription factors contributes to disease pathogenesis and found that LEC-specific deletion of Hif-2α exacerbated lymphedema pathology. Even without lymphatic vascular injury, the loss of LEC-specific Hif-2α caused anatomic pathology and a functional decline in fetal and adult mice. These findings suggest that HIF-2α is an important mediator of lymphatic health. HIF-2α promoted protective phosphorylated TIE2 (p-TIE2) signaling in LECs, a process also replicated by upregulating TIE2 signaling through adenovirus-mediated angiopoietin-1 (Angpt1) gene therapy. Our study suggests that HIF-2α normally promotes healthy lymphatic homeostasis and raises the exciting possibility that restoring HIF-2α pathways in lymphedema could mitigate long-term pathology and disability.
Xinguo Jiang, Wen Tian, Eric J. Granucci, Allen B. Tu, Dongeon Kim, Petra Dahms, Shravani Pasupneti, Gongyong Peng, Yesl Kim, Amber H. Lim, F. Hernan Espinoza, Matthew Cribb, J. Brandon Dixon, Stanley G. Rockson, Gregg L. Semenza, Mark R. Nicolls
Characterization of the key cellular targets contributing to sustained microglial activation in neurodegenerative diseases, including Parkinson’s disease (PD), and optimal modulation of these targets can provide potential treatments to halt disease progression. Here, we demonstrated that microglial Kv1.3, a voltage-gated potassium channel, was transcriptionally upregulated in response to aggregated α-synuclein (αSynAgg) stimulation in primary microglial cultures and animal models of PD, as well as in postmortem human PD brains. Patch-clamp electrophysiological studies confirmed that the observed Kv1.3 upregulation translated to increased Kv1.3 channel activity. The kinase Fyn, a risk factor for PD, modulated transcriptional upregulation and posttranslational modification of microglial Kv1.3. Multiple state-of-the-art analyses, including Duolink proximity ligation assay imaging, revealed that Fyn directly bound to Kv1.3 and posttranslationally modified its channel activity. Furthermore, we demonstrated the functional relevance of Kv1.3 in augmenting the neuroinflammatory response by using Kv1.3-KO primary microglia and the Kv1.3-specific small-molecule inhibitor PAP-1, thus highlighting the importance of Kv1.3 in neuroinflammation. Administration of PAP-1 significantly inhibited neurodegeneration and neuroinflammation in multiple animal models of PD. Collectively, our results imply that Fyn-dependent regulation of Kv1.3 channels plays an obligatory role in accentuating the neuroinflammatory response in PD and identify Kv1.3 as a potential therapeutic target for PD.
Souvarish Sarkar, Hai M. Nguyen, Emir Malovic, Jie Luo, Monica Langley, Bharathi N. Palanisamy, Neeraj Singh, Sireesha Manne, Matthew Neal, Michelle Gabrielle, Ahmed Abdalla, Poojya Anantharam, Dharmin Rokad, Nikhil Panicker, Vikrant Singh, Muhammet Ay, Adhithiya Charli, Dilshan Harischandra, Lee-Way Jin, Huajun Jin, Srikant Rangaraju, Vellareddy Anantharam, Heike Wulff, Anumantha G. Kanthasamy
Gasdermin D (GSDMD) induces pyroptosis via the pore-forming activity of its N-terminal domain, cleaved by activated caspases associated with the release of IL-1β. Here, we report a nonpyroptotic role of full-length GSDMD in guiding the release of IL-1β–containing small extracellular vesicles (sEVs) from intestinal epithelial cells (IECs). In response to caspase-8 inflammasome activation, GSDMD, chaperoned by Cdc37/Hsp90, recruits the E3 ligase, NEDD4, to catalyze polyubiquitination of pro–IL-1β, serving as a signal for cargo loading into secretory vesicles. GSDMD and IL-1β colocalize with the exosome markers CD63 and ALIX intracellularly, and GSDMD and NEDD4 are required for release of CD63+ sEVs containing IL-1β, GSDMD, NEDD4, and caspase-8. Importantly, increased expression of epithelial-derived GSDMD is observed both in patients with inflammatory bowel disease (IBD) and those with experimental colitis. While GSDMD-dependent release of IL-1β–containing sEVs is detected in cultured colonic explants from colitic mice, GSDMD deficiency substantially attenuates disease severity, implicating GSDMD-mediated release of IL-1β sEVs in the pathogenesis of intestinal inflammation, such as that observed in IBD.
Katarzyna Bulek, Junjie Zhao, Yun Liao, Nitish Rana, Daniele Corridoni, Agne Antanaviciute, Xing Chen, Han Wang, Wen Qian, William A. Miller-Little, Shadi Swaidani, Fangqiang Tang, Belinda B. Willard, Keith McCrae, Zizhen Kang, George R. Dubyak, Fabio Cominelli, Alison Simmons, Theresa T. Pizarro, Xiaoxia Li
NF-kB transcription factors, driven by the IRAK-IKK cascade, confer treatment resistance in pancreatic ductal adenocarcinoma (PDAC), a cancer characterized by near universal KRAS mutation. Through reverse-phase protein array and RNAseq we discovered IRAK4 also contributes substantially to MAPK activation in KRAS-mutant PDAC. IRAK4 ablation completely blocked RAS-induced transformation of human and murine cells. Mechanistically, expression of mutant KRAS stimulated an inflammatory, autocrine IL-1b signaling loop that activated IRAK4 and MAPK pathway. Downstream of IRAK4, we uncovered TPL2/MAP3K8 as the essential kinase that propels both MAPK and NF-kB cascades. Inhibition of TPL2 blocked both MAPK and NF-kB signaling, and suppressed KRAS-mutant cell growth. To counter chemotherapy-induced genotoxic stress, PDAC cells upregulated TLR9, which activated pro-survival IRAK4-TPL2 signaling. Accordingly, TPL2 inhibitor synergized with chemotherapy to curb PDAC growth in vivo. Finally, from TCGA we characterized two MAP3K8 point mutations that hyperactivate MAPK and NF-kB cascades by impeding TPL2 protein degradation. Cancer cell lines naturally harboring these MAP3K8 mutations are strikingly sensitive to TPL2 inhibition, underscoring the need to identify these potentially targetable mutations in patients. Overall, our study establishes TPL2 as a promising therapeutic target in RAS- and MAP3K8-mutant cancers and strongly prompts development of TPL2 inhibitors for pre-clinical and clinical studies.
Paarth B. Dodhiawala, Namrata Khurana, Daoxiang Zhang, Yi Cheng, Lin Li, Qing Wei, Kuljeet Seehra, Hongmei Jiang, Patrick M. Grierson, Andrea Wang-Gillam, Kian-Huat Lim
Alzheimer’s disease (AD) is characterized by amyloid-β-containing plaques and neurofibrillary tangles composed of aggregated, hyperphosphorylated tau. Beyond tau and Aβ, evidence suggests that microglia play an important role in AD pathogenesis. Rare variants in the microglial-expressed triggering receptor expressed on myeloid cells 2 (TREM2) gene increase AD risk 2-4-fold. It is likely that these TREM2 variants increase AD risk by decreasing the response of microglia to Aβ and its local toxicity. However, neocortical Aβ pathology occurs many years before neocortical tau pathology in AD. Thus, it will be important to understand the role of TREM2 in the context of tauopathy. We investigated the impact of the AD-associated TREM2 variant (R47H) on tau-mediated neuropathology in the PS19 mouse model of tauopathy. We assessed PS19 mice expressing human TREM2CV (common variant) or human TREM2R47H. PS19-T2R47H mice had significantly attenuated brain atrophy and synapse loss versus PS19-T2CV mice. Gene expression analyses and CD68 immunostaining revealed attenuated microglial reactivity in PS19-T2R47H versus PS19-T2CV mice. There was also a decrease in phagocytosis of postsynaptic elements by microglia expressing TREM2R47H in the PS19 mice and in human AD brains. These findings suggest that impaired TREM2 signaling reduces microglia-mediated neurodegeneration in the setting of tauopathy.
Maud Gratuze, Cheryl E.G. Leyns, Andrew D. Sauerbeck, Marie-Kim St-Pierre, Monica Xiong, Nayeon Kim, Javier Remolina Serrano, Marie-Ève Tremblay, Terrance T. Kummer, Marco Colonna, Jason D. Ulrich, David M. Holtzman
No posts were found with this tag.