BACKGROUND. Survivors of pneumonia, including SARS-CoV-2 pneumonia, are at increased risk for cognitive dysfunction and dementia. In rodent models, cognitive dysfunction following pneumonia has been linked to the systemic release of lung-derived pro-inflammatory cytokines. Microglia are poised to respond to inflammatory signals from the circulation, and their dysfunction has been linked to cognitive impairment in murine models of dementia and in humans. METHODS. We measured the levels of 55 cytokines and chemokines in bronchoalveolar lavage fluid and plasma from a cohort of 341 patients with respiratory failure and 13 healthy control patients, including 93 unvaccinated patients with COVID-19 and 203 patients with other causes of pneumonia. We flow-cytometry sorted neuroimmune cells from postmortem brain tissue from 5 patients who died from COVID-19 and 3 patients who died from other causes for single-cell RNA-sequencing. RESULTS. Microglia from patients with COVID-19 exhibited a transcriptomic signature suggestive of their activation by circulating pro-inflammatory cytokines. Peak levels of pro-inflammatory cytokines were similar in patients with pneumonia irrespective of etiology, but cumulative cytokine exposure was higher in patients with COVID-19. Treatment with corticosteroids reduced expression of COVID-19-specific cytokines. CONCLUSIONS. Prolonged lung inflammation results in sustained elevations in circulating cytokines patients with SARS-CoV-2 pneumonia compared to those with pneumonia secondary to other pathogens. Microglia from patients with COVID-19 exhibit transcriptional responses to inflammatory cytokines. These findings support data from rodent models causally linking systemic inflammation with cognitive dysfunction in pneumonia and support further investigation into the role of microglia in pneumonia-related cognitive dysfunction. FUNDING. SCRIPT U19AI135964.
Rogan A. Grant, Taylor A. Poor, Lango Sichizya, Estefani Diaz, Joseph I. Bailey, Sahil Soni, Karolina J. Senkow, Xóchitl G. Pérez-Leonor, Hiam Abdala-Valencia, Ziyan Lu, Helen K. Donnelly, Lacy M. Simons, Egon A. Ozer, Robert M. Tighe, Jon W. Lomasney, Richard G. Wunderink, Benjamin D. Singer, Alexander V. Misharin, G.R. Scott Budinger
IL-17C is an epithelial cell-derived proinflammatory cytokine whose transcriptional regulation remains unclear. Analysis of the IL17C promoter region identified TCF4 as putative regulator and siRNA knockdown of TCF4 in human keratinocytes (KCs) increased IL17C. IL-17C stimulation of KCs (along with IL-17A and TNF-α) decreased TCF4 and increased NFKBIZ and ZC3H12A expression in an IL-17RA/RE-dependent manner thus creating a feedback loop. ZC3H12A (MCPIP1/Regnase-1), a transcriptional immune-response regulator also increased following TCF4 siRNA knockdown and siRNA knockdown of ZC3H12A decreased NFKBIZ, IL1B, IL36G, CCL20, and CXCL1, revealing a proinflammatory role for ZC3H12A. Examination of lesional skin from the KC-Tie2 inflammatory dermatitis mouse model identified decreases in TCF4 protein concomitant with increases in IL-17C and Zc3h12a, that reversed following the genetic elimination of Il17c, Il17ra, and Il17re and improvement in the skin phenotype. Conversely, interference with Tcf4 in KC-Tie2 mouse skin increased Il17c and exacerbated the inflammatory skin phenotype. Together these findings identify a role for TCF4 in the negative regulation of IL-17C, which alone and with TNF-α and IL-17A, feedback to decrease TCF4 in an IL-17RA/RE-dependent manner. This loop is further amplified by IL-17C-TCF4 autocrine regulation of ZC3H12A and IL-17C regulation of NFKBIZ to promote self-sustaining skin inflammation.
Yanyun Jiang, Dennis Gruszka, Chang Zeng, William R. Swindell, Christa Gaskill, Christian Sorensen, Whitney Brown, Roopesh Singh Gangwar, Lam C. Tsoi, Joshua Webster, Sigrun Laufey Sigurdardottir, Mrinal K. Sarkar, Ranjitha Uppala, Austin Kidder, Xianying Xing, Olesya Plazyo, Enze Xing, Allison C. Billi, Emanual Maverakis, J. Michelle Kahlenberg, Johann Gudjonsson, Nicole L. Ward
Allergic Airway Disease (AAD) is an example of type 2 inflammation which leads to chronic airway eosinophilia controlled by CD4 Th2 cells. Inflammation is reinforced by mast cells and basophils armed with allergen-specific IgE made by allergen-specific B2 B cells of the adaptive immune system. Little is known about how AAD is affected by innate B1 cells which produce natural antibodies (NAbs) that facilitate apoptotic cell clearance and detect damage and pathogen associated molecular patterns (DAMPS and PAMPS). We used transgenic mouse models lacking either B cells or NAbs in distinct mouse models of AAD, that require either DAMPS or PAMPS as the initial trigger for type 2 immunity. In a DAMP-induced allergic model, driven by alum and uric acid, mouse strains lacking B cells (CD19DTA), NAbs (IgHEL MD4), or all secreted antibodies (sIgm-/-Aid-/-), displayed significant reduction in both eosinophilia and Th2 priming compared to wild-type or Aid-/- mice lacking only germinal center dependent high-affinity class switched antibodies. Replenishing B-cell deficient mice with either unimmunized B1 B cells or NAbs during sensitization restored eosinophilia, suggesting NAbs are required for licensing antigen presenting cells to prime type 2 immunity. Conversely, PAMP-dependent type 2 priming to house dust mite or Aspergillus were not dependent on NAbs. This study reveals an underappreciated role of B1 B cell-generated natural antibodies in selectively driving DAMP-induced type-2 immunity.
Arlind B. Mara, Kavita Rawat, William T. King, Claudia V. Jakubzick
Efficient clearance and degradation of apoptotic cardiomyocytes by macrophages (collectively termed efferocytosis) is critical for inflammation resolution and restoration of cardiac function after myocardial ischemia/reperfusion (I/R). Here, we define secreted and transmembrane protein 1a (Sectm1a), a cardiac macrophage–enriched gene, as a modulator of macrophage efferocytosis in I/R-injured hearts. Upon myocardial I/R, Sectm1a-KO mice exhibited impaired macrophage efferocytosis, leading to massive accumulation of apoptotic cardiomyocytes, cardiac inflammation, fibrosis, and consequently, exaggerated cardiac dysfunction. By contrast, therapeutic administration of recombinant SECTM1A protein significantly enhanced macrophage efferocytosis and improved cardiac function. Mechanistically, SECTM1A could elicit autocrine effects on the activation of glucocorticoid-induced TNF receptor (GITR) at the surface of macrophages, leading to the upregulation of liver X receptor α (LXRα) and its downstream efferocytosis-related genes and lysosomal enzyme genes. Our study suggests that Sectm1a-mediated activation of the Gitr/LXRα axis could be a promising approach to enhance macrophage efferocytosis for the treatment of myocardial I/R injury.
Xiaohong Wang, Wa Du, Yutian Li, Hui-Hui Yang, Yu Zhang, Rubab Akbar, Hannah Morgan, Tianqing Peng, Jing Chen, Sakthivel Sadayappan, Yueh-Chiang Hu, Yanbo Fan, Wei Huang, Guo-Chang Fan
IL-33 is a cytokine central to type 2 immune pathology in chronic airway disease. This cytokine is abundantly expressed in the respiratory epithelium and increased in disease, but how expression is regulated is undefined. Here we show that increased IL33 expression occurs from multiple noncanonical promoters in human chronic obstructive pulmonary disease (COPD), and it facilitates production of alternatively spliced isoforms in airway cells. We found that phorbol 12-myristate 13-acetate (PMA) can activate IL33 promoters through protein kinase C in primary airway cells and lines. Transcription factor (TF) binding arrays combined with RNA interference identified activator protein (AP) TFs as regulators of baseline and induced IL33 promoter activity. ATAC-Seq and ChIP-PCR identified chromatin accessibility and differential TF binding as additional control points for transcription from noncanonical promoters. In support of a role for these TFs in COPD pathogenesis, we found that AP-2 (TFAP2A, TFAP2C) and AP-1 (FOS and JUN) family members are upregulated in human COPD specimens. This study implicates integrative and pioneer TFs in regulating IL33 promoters and alternative splicing in human airway basal cells. Our work reveals a potentially novel approach for targeting IL-33 in development of therapeutics for COPD.
Heather E. Raphael, Ghandi F. Hassan, Omar A. Osorio, Lucy S. Cohen, Morgan D. Payne, Ella Katz-Kiriakos, Ishana Tata, Jamie Hicks, Derek E. Byers, Bo Zhang, Jen Alexander-Brett
Programmed cell death protein 1 (PD-1), a coinhibitory T-cell checkpoint, is also expressed on macrophages (Mφ) in pathogen- or tumor-driven chronic inflammation. Increasing evidence underscores the importance of PD-1 on Mφ for dampening immune responses. However, the mechanism governing PD-1 expression in Mφ in chronic inflammation remains largely unknown. TGF-β1 (transforming growth factor-β1) is abundant within chronic inflammatory microenvironments. Here, based on public databases, significant positive correlations between PDCD1 and TGFB1 gene expression were observed in most human tumors. Of note, among immune infiltrates, Mφ as the predominant infiltrate expressed higher PDCD1 and TGFBR1/TGFBR2 genes. MC38 colon cancer and S. japonicum infection were used as experimental models for chronic inflammation. PD-1hi Mφ from chronic inflammatory tissues displayed an immunoregulatory pattern and expressed a higher level of TGF-β receptors. Either TGF-β1-neutralizing antibody administration or Mφ-specific Tgfbr1 knockdown largely reduced PD-1 expression on Mφ in animal models. We further demonstrated that TGF-β1 directly induced PD-1 expression on Mφ. Mechanistically, TGF-β1-induced PD-1 expression on Mφ was dependent on SMAD3 and STAT3, which formed a complex at the Pdcd1 promoter. Collectively, our study shows that Mφ adapt to chronic inflammation through TGF-β1-triggered cooperative SMAD3-STAT3 signaling that induces PD-1 expression and modulates Mφ function.
Zhigang Lei, Rui Tang, Yu Wu, Chenxu Mao, Weijie Xue, Junyao Shen, Jiaojiao Yu, Xiaohong Wang, Xin Qi, Chuan Wei, Lei Xu, Jifeng Zhu, Yalin Li, Xiujun Zhang, Chunyan Ye, Xiaojun Chen, Xiaojun Yang, Sha Zhou, Chuan Su
The lipidome of immune cells during infection has remained unexplored, although evidence of the importance of lipids in the context of immunity is mounting. In this study, we performed untargeted lipidomic analysis of blood monocytes and neutrophils from patients hospitalized for pneumonia and age- and sex-matched noninfectious control volunteers. We annotated 521 and 706 lipids in monocytes and neutrophils, respectively, which were normalized to an extensive set of internal standards per lipid class. The cellular lipidomes were profoundly altered in patients, with both common and distinct changes between the cell types. Changes involved every level of the cellular lipidome: differential lipid species, class-wide shifts, and altered saturation patterns. Overall, differential lipids were mainly less abundant in monocytes and more abundant in neutrophils from patients. One month after hospital admission, lipidomic changes were fully resolved in monocytes and partially in neutrophils. Integration of lipidomic and concurrently collected transcriptomic data highlighted altered sphingolipid metabolism in both cell types. Inhibition of ceramide and sphingosine-1-phosphate synthesis in healthy monocytes and neutrophils resulted in blunted cytokine responses upon stimulation with lipopolysaccharide. These data reveal major lipidomic remodeling in immune cells during infection, and link the cellular lipidome to immune functionality.
Alex R. Schuurman, Osoul Chouchane, Joe M. Butler, Hessel Peters-Sengers, Sebastiaan Joosten, Xanthe Brands, Bastiaan W. Haak, Natasja A. Otto, Fabrice Uhel, Augustijn Klarenbeek, Christine C.A. van Linge, Antoine van Kampen, Mia Pras-Raves, Michel van Weeghel, Marco van Eijk, Maria J. Ferraz, Daniël R. Faber, Alex de Vos, Brendon P. Scicluna, Frédéric M. Vaz, W. Joost Wiersinga, Tom van der Poll
Dynamic regulation of cellular metabolism is important for maintaining homeostasis and can directly influence immune cell function and differentiation, including NK cell responses. Persistent HIV-1 infection leads to a state of chronic immune activation, NK cell subset redistribution, and progressive NK cell dysregulation. In this study, we examined the metabolic processes that characterize NK cell subsets in HIV-1 infection, including adaptive NK cell subpopulations expressing the activating receptor NKG2C, which expand during chronic infection. These adaptive NK cells exhibit an enhanced metabolic profile in HIV-1– individuals infected with human cytomegalovirus (HCMV). However, the bioenergetic advantage of adaptive CD57+NKG2C+ NK cells is diminished during chronic HIV-1 infection, where NK cells uniformly display reduced oxidative phosphorylation (OXPHOS). Defective OXPHOS was accompanied by increased mitochondrial depolarization, structural alterations, and increased DRP-1 levels promoting fission, suggesting that mitochondrial defects are restricting the metabolic plasticity of NK cell subsets in HIV-1 infection. The metabolic requirement for the NK cell response to receptor stimulation was alleviated upon IL-15 pretreatment, which enhanced mammalian target of rapamycin complex 1 (mTORC1) activity. IL-15 priming enhanced NK cell functionality to anti-CD16 stimulation in HIV-1 infection, representing an effective strategy for pharmacologically boosting NK cell responses.
Elia Moreno-Cubero, Aljawharah Alrubayyi, Stefan Balint, Ane Ogbe, Upkar S. Gill, Rebecca Matthews, Sabine Kinloch, Fiona Burns, Sarah L. Rowland-Jones, Persephone Borrow, Anna Schurich, Michael Dustin, Dimitra Peppa
In autoimmunity, FOXP3+ regulatory T cells (Tregs) skew towards a pro-inflammatory, non-suppressive phenotype and are therefore unable to control the exaggerated autoimmune response. This largely impacts the success of autologous Treg therapy which is currently under investigation for autoimmune diseases, including multiple sclerosis (MS). There is a need to ensure in vivo Treg stability before successful application of Treg therapy. Using genetic fate-mapping mice, we demonstrate that inflammatory, cytokine-expressing exFOXP3 T cells accumulate in the central nervous system during experimental autoimmune encephalomyelitis. In a human in vitro model, we discovered that interaction with inflamed blood-brain barrier endothelial cells (BBB-ECs) induces loss-of-function by Tregs. Transcriptome and cytokine analysis revealed that in vitro migrated Tregs have disrupted regenerative potential, a pro-inflammatory Th1/17 signature and upregulate the mTORC1 signaling pathway. In vitro treatment of migrated human Tregs with the clinically-approved mTORC1 inhibitor rapamycin restored suppression. Finally, flow cytometric analysis indicated an enrichment of inflammatory, less suppressive CD49d+ Tregs in the cerebrospinal fluid of people with MS. In sum, interaction with BBB-ECs is sufficient to affect Treg function, and transmigration triggers an additive pro-inflammatory phenotype switch. These insights help improve the efficacy of autologous Treg therapy of MS.
Paulien Baeten, Ibrahim Hamad, Cindy Hoeks, Michael Hiltensperger, Bart Van Wijmeersch, Veronica Popescu, Lilian Aly, Veerle Somers, Thomas Korn, Markus Kleinewietfeld, Niels Hellings, Bieke Broux
The efficacy of chimeric antigen receptor (CAR)-T therapy has been limited against brain tumors to date. CAR-T cells infiltrating syngeneic intracerebral SB28-EGFRvIII glioma revealed impaired mitochondrial ATP production and a markedly hypoxic status compared to ones migrating to subcutaneous tumors. Drug screenings to improve metabolic states of T cells under hypoxic conditions led us to evaluate the combination of AMPK activator Metformin and the mTOR inhibitor Rapamycin (Met+Rap). Met+Rap-pretreated mouse CAR-T cells showed activated PPAR-gamma coactivator 1α (PGC-1α) through mTOR inhibition and AMPK activation, and a higher level of mitochondrial spare respiratory capacity than those pretreated with individual drugs or without pretreatment. Moreover, Met+Rap-pretreated CAR-T cells demonstrated persistent and effective anti-glioma cytotoxic activities in the hypoxic condition. Furthermore, a single intravenous infusion of Met+Rap-pretreated CAR-T cells significantly extended the survival of mice bearing intracerebral SB28-EGFRvIII gliomas. Mass cytometric analyses highlighted increased glioma-infiltrating CAR-T cells in the Met+Rap group with fewer Ly6c+ CD11b+ monocytic myeloid-derived suppressor cells in the tumors. Finally, human CAR-T cells pretreated with Met+Rap recapitulated the observations with murine CAR-T cells, demonstrating improved functions in vitro hypoxic conditions. These findings advocate for translational and clinical exploration of Met+Rap-pretreated CAR-T cells in human trials.
Ryusuke Hatae, Keith Kyewalabye, Akane Yamamichi, Tiffany Chen, Su Phyu, Pavlina Chuntova, Takahide Nejo, Lauren S. Levine, Matthew H. Spitzer, Hideho Okada
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