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Abstract
As sufficient extracellular arginine is crucial for T cell function, depletion of extracellular arginine by elevated Arginase 1 (Arg1) activity has emerged as a hallmark immunosuppressive mechanism. However, the potential cell-autonomous roles of arginases in T cells have remained unexplored. Here we show that the arginase isoform expressed by T cells, the mitochondrial Arginase 2 (Arg2), is a cell-intrinsic regulator of CD8+ T cell activity. Both germ-line Arg2 deletion and adoptive transfer of Arg2-/- CD8+ T cells significantly reduced tumor growth in preclinical cancer models by enhancing CD8+ T cell activation, effector function and persistence. Transcriptomic, proteomic and high-dimensional flow cytometry characterization revealed a CD8+ T cell-intrinsic role of Arg2 in modulating T cell activation, anti-tumor cytoxicity and memory formation, independently of extracellular arginine availability. Furthermore, specific deletion of Arg2 in CD8+ T cells strongly synergized with PD-1 blockade for the control of tumor growth and animal survival. These observations coupled with the finding that pharmacologic arginase inhibition accelerates activation of ex vivo human T cells unveil Arg2 as a new therapeutic target for T cell-based cancer therapies.
Authors
Adrià-Arnau Martí i Líndez, Isabelle Dunand-Sauthier, Mark Conti, Florian Gobet, Nicolás Núñez, J. Thomas Hannich, Howard Riezman, Geiger Roger, Alessandra Piersigilli, Kerstin Hahn, Sylvain Lemeille, Burkhard Becher, Thibaut De Smedt, Stéphanie Hugues, Walter Reith
Abstract
Proteinuric chronic kidney disease (CKD) remains a major health problem worldwide. While the progression of primary glomerular disease to induce tubulointerstitial lesions is well established, the effect of tubular injury to trigger glomerular damage is poorly understood. We hypothesized that injured tubules secrete mediators that adversely affect glomerular health. To test this, we utilized conditional knockout mice with tubule-specific ablation of β-catenin (Ksp-β-cat-/-), and subjected them to chronic angiotensin II (Ang II) infusion or adriamycin. Compared to control mice, Ksp-β-cat-/- mice were dramatically protected from proteinuria and glomerular damage. Matrix metalloproteinase-7 (MMP-7), a downstream target of β-catenin, was upregulated in treated control mice, but this induction was blunted in the Ksp-β-cat-/- littermates. Incubation of isolated glomeruli with MMP-7 ex vivo led to nephrin depletion and impaired glomerular permeability. Furthermore, MMP-7 specifically and directly degraded nephrin in cultured glomeruli or cell-free systems, and this effect was dependent on its proteolytic activity. In vivo, expression or infusion of exogenous MMP-7 caused proteinuria, and genetic ablation of MMP-7 protected mice from Ang II-induced proteinuria and glomerular injury. Collectively, these results demonstrate that beta-catenin-driven MMP-7 release from renal tubules promotes glomerular injury via direct degradation of the key slit diaphragm protein nephrin.
Authors
Roderick J. Tan, Yingjian Li, Brittney M. Rush, Débora Malta Cerqueira, Dong Zhou, Haiyan Fu, Jacqueline Ho, Donna Beer Stolz, Youhua Liu
Abstract
Background: Bacille Calmette-Guérin (BCG) vaccine is protective in children but its efficacy wanes with age. Consequently, determining if BCG revaccination augments anti-TB immunity in young adults in TB endemic regions is vital. Methods: 200 healthy adults, BCG vaccinated at birth were tested for their IGRA status. Of these, 28 IGRA+ and 30 IGRA- were BCG revaccinated and 24 IGRA+ and 23 IGRA- subjects served as unvaccinated controls. T and innate cell responses to mycobacterial antigens were analyzed by 14-colour flow cytometry over 34 weeks. Results: IFN-γ and/or IL-2 Ag85A and BCG-specific CD4+ and CD8+ T-cell responses were boosted by revacciantion at 4 and 34 weeks respectively and were >2-fold higher in IGRA+ compared to IGRA- vaccinees. Polyfunctional Ag85A, BCG and Mtb latency Ag (LTAg)-specific CD4+ T-cells expressing up to 8 cytokines were also significantly enhanced in both IGRA+ and IGRA- vaccinees relative to unvaccinated controls, most markedly in IGRA+ vaccinees. A focussed analysis of Th17 responses revealed expansion of Ag85A, BCG and LTAg-specific total IL-17A+IL-17F+IL-22+ and IL-10+ CD4+ T-cell effectors in both IGRA+ and IGRA- subjects. Also, innate IFN-γ+ NK/γδ/NKT responses were higher in both IGRA+ and IGRA- vaccinees compared to controls. This is the first evidence that BCG revaccination significantly boosts anti-mycobacterial Th1/Th17 responses in IGRA+ and IGRA- subjects. Summary: These data show that BCG revaccination is immunogenic in IGRA- and IGRA+ subjects implying that Mtb pre-infection in IGRA+ subjects does not impact immunogenicity. This has implications for public health and vaccine development strategies. Funding: This work was funded principally by DBT-NIH (BT/MB/Indo-US/HIPC/2013).
Authors
Srabanti Rakshit, Asma Ahmed, Vasista Adiga, Bharath K. Sundararaj, Pravat Nalini Sahoo, John Kenneth, George D'Souza, Wesley Bonam, Christina Johnson, Kees L.M.C. Franken, Tom H.M. Ottenhoff, Greg Finak, Raphael Gottardo, Kenneth D. Stuart, Stephen C. De Rosa, M. Juliana McElrath, Annapurna Vyakarnam
Abstract
Introduction: The airways of obese asthmatics have been shown to be nitric oxide (NO) deficient, which contributes to airway dysfunction and reduced response to inhaled corticosteroids (ICS). In cultured airway epithelial cells, L-citrulline, a precursor of L-arginine recycling and NO formation, has been shown to prevent asymmetric di-methyl arginine (ADMA)-mediated NO synthase (NOS2) uncoupling, restoring NO and reducing oxidative stress. Methods: In a proof of concept, pre – post open label pilot study, we hypothesized that 15g/day of L-citrulline for two weeks would: a) increase the fractional excretion of NO (FeNO); b) improve asthma control and c) improve lung function. To do this, we recruited obese (body mass index [BMI] >30) asthmatics on controller therapy with a baseline fractional exhaled nitric oxide (FeNO) ≤ 30 ppb from the University of Colorado Medical Center and Duke University Health System. Results: A total of 41 subjects with an average FeNO of 17 ppb (95% 19 - 20) and poorly controlled asthma (average asthma control questionnaire [ACQ] 1.5 [95% 1.2 – 1.8) completed the study. Compared to baseline, L-citrulline increased (values represent the mean delta and 95%CI): plasma L-citrulline (190uM, 84 – 297), plasma L-arginine (67uM, 38 – 95), plasma L-arginine/ADMA (117, 67 - 167), but not ADMA or arginase concentration. FeNO increased by 4.2ppb (1.7 – 6.7); ACQ decreased by -0.46 (-0.67 – -0.27); the forced vital capacity (FVC) and forced exhalation volume in one second (FEV1) respectively changed by 86 ml (10 – 161), and 52 ml (-11 – 132). In a secondary analysis, the greatest FEV1 increments occurred in those subjects with late onset asthma (>12 years) (63 ml [95%CI 1 – 137]), in females (80 ml [95%CI 5 – 154]), with a greater change seen in late onset females (100ml, [95%CI 2 – 177]). The changes in lung function or asthma control were not significantly associated with the pre-post changes in L-arginine/ADMA or FeNO. Conclusion: Short-term L-citrulline treatment improved asthma control and FeNO levels in obese asthmatics with low or normal FeNO. Larger FEV1 increments were observed in those with late onset asthma and in females.
Authors
Fernando Holguin, Hartmut Grasemann, Sunita Sharma, Daniel Winnica, Karen Wasil, Vong Smithphone, Margaret H. Cruse, Nancy Perez, Erika Coleman, Timothy J. Scialla, Loretta Que
Abstract
Patients with Duchene Muscular Dystrophy (DMD) commonly present severe ventricular arrhythmias that contribute to heart failure. Arrhythmias and lethality are also consistently observed in adult Dmdmdx mice, a mouse model of DMD, after acute β-adrenergic stimulation. These pathological features were previously linked to aberrant expression and remodeling of the cardiac gap junction protein connexin 43 (Cx43). Here, we report that remodeled Cx43 protein forms Cx43 hemichannels in the lateral membrane of Dmdmdx cardiomyocytes and that the β -adrenergic agonist isoproterenol (Iso) aberrantly activates these hemichannels. Block of Cx43 hemichannels or a reduction in Cx43 levels (using Dmdmdx:Cx43+/- mice) prevents the abnormal increase in membrane permeability, plasma membrane depolarization and Iso-evoked electrical activity in these cells. Additionally, Iso treatment promotes nitric oxide (NO) production and S-nitrosylation of Cx43 hemichannels in Dmdmdx heart. Importantly, inhibition of NO production prevents arrhythmias evoked by Iso. We found that NO directly activates Cx43 hemichannels by S-nitrosylation of cysteine at the position 271. Our results demonstrate that opening of remodeled and S-nitrosylated Cx43 hemichannels play a key role in the development of arrhythmias in DMD mice and may serve as therapeutic targets to prevent fatal arrhythmias in DMD patients.
Authors
Mauricio A. Lillo, Eric Himelman, Natalia Shirokova, Lai-Hua Xie, Diego Fraidenraich, Jorge E. Contreras
Abstract
Immune activation is associated with increased risk of tuberculosis (TB) disease in infants. We performed a case control analysis to identify drivers of immune activation and disease risk. Among 49 infants who developed TB disease over the first two years of life, and 129 matched controls who remained healthy, we found the cytomegalovirus (CMV) stimulated IFNγ response at age 4-6 months to be associated with CD8+ T cell activation (Spearmans rho, P = 6 x 10-8). A CMV specific IFNγ response was also associated with increased risk of developing TB disease (Conditional Logistic Regression, P = 0.043, OR 2.2, 95% CI 1.02-4.83), and shorter time to TB diagnosis (Log Rank Mantel-Cox P = 0.037). CMV positive infants who developed TB disease had lower expression of natural killer cell associated gene signatures and a lower frequency of CD3−CD4−CD8− lymphocytes. We identified transcriptional signatures predictive of risk of TB disease among CMV ELISpot positive (AUROC 0.98, accuracy 92.57%) and negative (AUROC 0.9, accuracy 79.3%) infants; the CMV negative signature validated in an independent infant study (AUROC 0.71, accuracy 63.9%). Understanding and controlling the microbial drivers of T cell activation, such as CMV, could guide new strategies for prevention of TB disease in infants.
Authors
Julius Müller, Rachel Tanner, Magali Matsumiya, Margaret A. Snowden, Bernard Landry, Iman Satti, Stephanie A. Harris, Matthew K. O'Shea, Lisa Stockdale, Leanne Marsay, Agnieszka Chomka, Rachel Harrington-Kandt, Zita-Rose Manjaly Thomas, Elena Stylianou, Vivek Naranbhai, Stanley Kimbung Mbandi, Mark Hatherill, Gregory Hussey, Hassan Mahomed, Michele Tameris, J. Bruce McClain, Willem A. Hanekom, Thomas G. Evans, Thomas J. Scriba, Helen McShane, Helen A. Fletcher
Abstract
WHIM syndrome immunodeficiency is caused by autosomal dominant gain-of-function mutations in chemokine receptor CXCR4. Patient WHIM-09 was spontaneously cured by chromothriptic deletion of one copy of 164 genes, including the CXCR4WHIM allele, presumably in a single hematopoietic stem cell (HSC) that repopulated HSCs and the myeloid lineage. Testing the specific contribution of CXCR4 hemizygosity to her cure, we previously demonstrated enhanced engraftment of Cxcr4+/o HSCs after transplantation in WHIM (Cxcr4+/w) model mice, but the potency was not quantitated. We now report graded-dose competitive transplantation experiments using lethally irradiated Cxcr4+/+ recipients in which mixed BM cells containing ~5 Cxcr4+/o HSCs and a 100-fold excess of Cxcr4+/w HSCs achieved durable 50% Cxcr4+/o myeloid and B cell chimerism in blood and ~20% Cxcr4+/o HSC chimerism in BM. In Cxcr4+/o/Cxcr4+/w parabiotic mice, we observed 80-100% Cxcr4+/o myeloid and lymphoid chimerism in the blood and 15% Cxcr4+/o HSC chimerism in BM from the Cxcr4+/w parabiont, which was durable after separation from the Cxcr4+/o parabiont. Thus, CXCR4 haploinsufficiency likely significantly contributed to the selective repopulation of HSCs and the myeloid lineage from a single chromothriptic HSC in WHIM-09. Moreover, the results suggest that WHIM allele silencing of patient HSCs is a viable gene therapy strategy.
Authors
Ji-Liang Gao, Albert Owusu-Ansah, Andrea Paun, Kimberly Beacht, Erin Yim, Marie Siwicki, Alexander Yang, Qian Liu, David H. McDermott, Philip M. Murphy
Abstract
Accumulation of senescent cells is associated with the progression of pulmonary fibrosis but mechanisms accounting for this linkage are not well understood. To explore this issue, we investigated whether a class of biologically active profibrotic lipids, the leukotrienes (LT), is part of the senescence-associated secretory phenotype. The analysis of conditioned medium (CM) lipid extracts and gene expression of LT biosynthesis enzymes revealed that senescent cells secreted LT regardless of the origin of the cells or the modality of senescence induction. The synthesis of LT was biphasic and followed by anti-fibrotic prostaglandin (PG) secretion. The LT-rich CM of senescent lung fibroblasts (IMR90) induced pro-fibrotic signaling in naïve fibroblasts, which were abrogated by inhibitors of ALOX5, the principal enzyme in LT biosynthesis. The bleomycin-induced expression of genes encoding LT and PG synthases, level of cysteinyl leukotriene in the bronchoalveolar lavage, and overall fibrosis were reduced upon senescent cells removal either in a genetic mouse model or after senolytic treatment. Quantification of ALOX5+cells in lung explants obtained from idiopathic pulmonary fibrosis (IPF) patients indicated that half of these cells were also senescent (p16Ink4a+). Unlike human fibroblasts from unused donor lungs made senescent by irradiation, senescent IPF fibroblasts secreted LTs but failed to synthesize PGs. This study demonstrates for the first time that senescent cells secrete functional LTs, significantly contributing to the LTs pool known to cause or exacerbate IPF.
Authors
Christopher D. Wiley, Alexis N. Brumwell, Sonnet S. Davis, Julia R. Jackson, Alexis Valdovinos, Cheresa Calhoun, Fatouma Alimirah, Carlos A. Castellanos, Richard Ruan, Ying Wei, Harold A. Chapman, Arvind Ramanathan, Judith Campisi, Claude Jourdan Le Saux
Abstract
The HER2-specific monoclonal antibody (mAb), Trastuzumab, has been the mainstay of therapy for HER2+ breast cancers (BC) for ~20 years. However, its therapeutic mechanism of action (MOA) remains unclear, with antitumor responses to Trastuzumab remaining heterologous and metastatic HER2+ BC remaining incurable. Consequently, understanding its MOA could enable rational strategies to enhance its efficacy. Using both novel murine and human versions of Trastuzumab, we found its antitumor activity dependent on Fcγ-Receptor stimulation of tumor-associated-macrophages (TAM) and Antibody-Dependent-Cellular-Phagocytosis (ADCP), but not cytotoxicity (ADCC). Trastuzumab also stimulated TAM activation and expansion, but did not require adaptive immunity, natural killer cells, and/or neutrophils. Moreover, inhibition of the innate immune ADCP checkpoint, CD47, significantly enhanced Trastuzumab-mediated ADCP, TAM expansion and activation, resulting in the emergence of a unique hyper-phagocytic macrophage population, improved antitumor responses and prolonged survival. In addition, we found tumor-associated CD47 expression was inversely associated with survival in HER2+ BC patients and that human HER2+ BC xenografts treated with Trastuzumab+CD47 inhibition underwent complete tumor regression. Collectively, our study identifies Trastuzumab-mediated ADCP as a significant antitumor MOA that may be clinically enabled by CD47 blockade to augment therapeutic efficacy.
Authors
Li-Chung Tsao, Erika J. Crosby, Timothy N. Trotter, Pankaj Agarwal, Bin-Jin Hwang, Chaitanya Acharya, Casey W. Shuptrine, Tao Wang, Junping Wei, Xiao Yang, Gangjun Lei, Cong-Xiao Liu, Christopher A. Rabiola, Lewis A. Chodosh, William J. Muller, Herbert Kim Lyerly, Zachary C. Hartman
Abstract
Conventional treatments for inflammatory bowel disease (IBD) have multiple potential side effects. Therefore, alternative treatments are desperately needed. This work demonstrated that systemic administration of exosomes from human bone marrow-derived mesenchymal stromal cells (MSC-Exos) significantly mitigated colitis in various models of IBD. MSC-Exos treatment downregulated inflammatory responses, maintained intestinal barrier integrity and polarized M2b macrophages, but did not favor intestinal fibrosis. Mechanistically, infused MSC-Exos mainly acted on colonic macrophages and macrophages from colitic colons acquired obvious resistance to inflammatory re-stimulation when prepared from mice treated with MSC-Exos versus untreated mice. The beneficial effect of MSC-Exos was blocked by macrophage depletion. Besides, the induction of IL-10 production from macrophages was partially involved in the beneficial effect of MSC-Exos. MSC-Exos were enriched in proteins involved in regulating multiple biological processes associated with the anti-colitic benefit of MSC-Exos. Particularly, metallothionein-2 in MSC-Exos was required for the suppression of inflammatory responses. Taken together, MSC-Exos are critical regulators of inflammatory responses and may be promising candidates for IBD treatment.
Authors
Huashan Liu, Zhenxing Liang, Fengwei wang, Chi Zhou, Xiaobin Zheng, Tuo Hu, Xiaowen He, Xianrui Wu, Ping Lan
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