Serum amyloid A-containing HDL binds adipocyte-derived versican and macrophage-derived biglycan, reducing its anti-inflammatory properties

• Text
• PDF

Abstract

The ability of HDL to inhibit inflammation in adipocytes and adipose tissue is reduced when HDL contains serum amyloid A (SAA) due to trapping of SAA in HDL by proteoglycans at the adipocyte surface. Since we recently found that the major extracellular matrix proteoglycan produced by hypertrophic adipocytes is versican, whereas activated adipose tissue macrophages produce mainly biglycan, the role of proteoglycans in determining the anti-inflammatory properties of HDL was further investigated. The distribution of versican, biglycan, apolipoprotein A-I (the major apolipoprotein of HDL) and SAA were similar in adipose tissue from obese mice and obese human subjects. Co-localization of SAA-enriched HDL with versican and biglycan at the cell surface of adipocyte and peritoneal macrophages, respectively, was blocked by silencing these proteoglycans, which also restored the anti-inflammatory property of SAA-enriched HDL despite the presence of SAA. Similar to adipocytes, normal HDL exerts its anti-inflammatory function in macrophages by reducing lipid rafts, reactive oxygen species generation and translocation of toll like receptor 4 and NADPH oxidase 2 into lipid rafts, effects that are not observed with SAA-enriched HDL. These findings imply that SAA present in HDL can be trapped by adipocyte-derived versican and macrophage-derived biglycan, thereby blunting HDL’s anti-inflammatory properties.

Authors

Chang Yeop Han, Inkyung Kang, Mohamed Omer, Shari Wang, Tomasz Wietecha, Thomas N. Wight, Alan Chait

Dysregulation of tryptophan catabolism at the host-skin microbiota interface in Hidradenitis Suppurativa

• Text
• PDF

Abstract

Hidradenitis Suppurativa (HS) is a chronic skin disorder of unknown etiology that manifests as recurrent, painful lesions. Cutaneous dysbiosis and unresolved inflammation are hallmarks of active HS, but their origin and interplay remain unclear. Our metabolomic profiling of HS skin revealed an abnormal induction of the kynurenine pathway (KP) of tryptophan catabolism in dermal fibroblasts correlating with the release of KP-inducing cytokines by inflammatory cell infiltrates. Notably, over-activation of the KP in lesional skin was associated with local and systemic depletion in tryptophan. Yet the skin microbiota normally degrades host tryptophan into indoles regulating tissue inflammation via engagement of the Aryl Hydrocarbon Receptor (AHR). In HS skin lesions, we detected contextual defects in AHR activation coinciding with impaired production of bacteria-derived AHR agonists and decreased incidence of AHR ligand-producing bacteria in the resident flora. Dysregulation of tryptophan catabolism at the skin-microbiota interface thus provides a mechanism linking the immunological and microbiological features of HS lesions. In addition to revealing metabolic alterations in HS patients, our study suggests that correcting AHR signaling would help restore immune homeostasis in HS skin.

Authors

Laure Guenin-Macé, Jean-David Morel, Jean-Marc Doisne, Angèle Schiavo, Lysiane Boulet, Véronique Mayau, Pedro Goncalves, Sabine Duchatelet, Alain Hovnanian, Vincent Bondet, Darragh Duffy, Marie-Noëlle Ungeheuer, Maïa Delage, Aude Nassif, James P. Di Santo, Caroline Demangel

Inhibition of TRPV1 by SHP-1 in nociceptive primary sensory neurons is critical in PD-L1 analgesia

• Text
• PDF

Abstract

Recently programmed death-ligand 1 (PD-L1) receptor PD-1 was found in dorsal root ganglion (DRG) neurons, and PD-L1 activates PD-1 to inhibit inflammatory and neuropathic pain by modulating neuronal excitability. However, the downstream signaling of PD-1 in sensory neurons remains unclear. Here, we show that PD-L1 activates Src homology 2 domain-containing tyrosine phosphatase-1 (SHP-1) to downregulate transient receptor potential vanilloid 1 (TRPV1) in DRG neurons and inhibit bone cancer pain in mice. Local injection of PD-L1 produced analgesia. PD-1 in DRG neurons colocalized with TRPV1 and SHP-1. PD-L1 induced the phosphorylation of SHP-1 in DRG TRPV1 neurons and inhibited TRPV1 currents. Loss of TRPV1 in mice abolished bone cancer-induced thermal hyperalgesia and PD-L1 analgesia. Conditioned deletion of SHP-1 in NaV1.8+ neurons aggravated bone cancer pain and diminished the inhibition of PD-L1 on TRPV1 currents and pain. Together, our findings suggest that PD-L1/PD1 signaling suppress bone cancer pain via inhibition of TRPV1 activity. Our results also suggest that SHP-1 in sensory neurons is an endogenous pain inhibitor and delayed the development of bone cancer pain via suppressing TRPV1 function.

Authors

Ben-Long Liu, Qi-Lai Cao, Xin Zhao, Hui-Zhu Liu, Yu-Qiu Zhang

Schwannoma development is mediated by Hippo pathway dysregulation and modified by RAS/MAPK signaling

• Text
• PDF

Abstract

Schwannomas are tumors of the Schwann cells that cause chronic pain, numbness, and potentially life-threatening impairment of vital organs. Despite the identification of causative genes including NF2 (Merlin), INI1/SMARCB1, and LZTR1, the exact molecular mechanism of schwannoma development is still poorly understood. Several studies have identified Merlin as a key regulator of the Hippo, MAPK, and PI3K signaling pathways, however definitive evidence demonstrating the importance of these pathways in schwannoma pathogenesis is absent. Here, we provide direct genetic evidence that dysregulation of the Hippo pathway in the Schwann cell lineage causes development of multiple Schwannomas in mice. We found that canonical Hippo signaling through the effectors YAP/TAZ is required for schwannomagenesis and that MAPK signaling modifies schwannoma formation. Furthermore, co-targeting YAP/TAZ transcriptional activity and MAPK signaling demonstrated a synergistic therapeutic effect on schwannoma. Our new model provides a tractable platform to dissect the molecular mechanisms underpinning schwannoma formation and the role of combinatorial targeted therapy in schwannoma treatment.

Authors

Zhiguo Chen, Stephen Li, Juan Mo, Eric T. Hawley, Yong Wang, Yongzheng He, Jean-Philippe Brosseau, Tracey Shipman, D. Wade Clapp, Thomas J. Carroll, Lu Q. Le

ROS producing immature neutrophils in Giant Cell Arteritis are linked to vascular pathologies

• Text
• PDF

Abstract

Giant cell arteritis (GCA) is a common form of primary systemic vasculitis in adults with no reliable indicators of prognosis or treatment responses. We used single cell technologies to comprehensively map immune cell populations in the blood of patients with GCA and identified the CD66b+CD15+CD10lo/-CD64- band neutrophils and CD66bhiCD15+CD10lo/-CD64+/bright myelocytes/metamyelocytes to be unequivocally associated with both the clinical phenotype and response to treatment. Immature neutrophils were resistant to apoptosis, remained in the vasculature for a prolonged time, interacted with platelets, and extravasated into the tissue surrounding the temporal arteries of patients with GCA. We discovered that immature neutrophils generated high levels of extracellular reactive oxygen species, leading to enhanced protein oxidation and permeability of endothelial barrier in an in vitro co-culture system. The same populations were also detected in other systemic vasculitides. These findings link functions of immature neutrophils to disease pathogenesis, establishing a new clinical cellular signature of GCA and suggesting new therapeutic approaches in systemic vascular inflammation.

Authors

Lihui Wang, Zhichao Ai, Tariq E. Khoyratty, Kristina Zec, Hayley L. Eames, Erinke van Grinsven, Alison Hudak, Susan Morris, David J. Ahern, Claudia Monaco, Evgeniy B. Eruslanov, Raashid Luqmani, Irina A. Udalova

Renal proximal tubular NEMO plays a critical role in ischemic acute kidney injury

• Text
• PDF

Abstract

We determined that renal proximal tubular (PT) NFκB essential modulator (NEMO) plays a direct and critical role in ischemic acute kidney injury (AKI) utilizing using mice lacking renal PT NEMO and by targeted renal PT NEMO inhibition with mesoscale nanoparticle encapsulated NEMO binding peptide (MNP NBP). We subjected renal PT NEMO deficient mice, wild type (WT) mice and C57BL/6 mice to sham surgery or 30 min renal ischemia and reperfusion (IR). C57BL/6 mice received NBP MNP or empty MNP before renal IR injury. Mice treated with MNP NBP and mice deficient in renal PT NEMO were protected against ischemic AKI with decreased renal tubular necrosis, inflammation and apoptosis compared to control MNP treated or WT mice, respectively. Recombinant peptidylarginine deiminase type-4 (rPAD4) targets kidney PT NEMO to exacerbate ischemic AKI as exogenous rPAD4 exacerbated renal IR injury in WT mice but not in renal proximal tubule NEMO deficient mice. Furthermore, rPAD4 upregulated proinflammatory cytokine mRNA and NFκB activation in freshly isolated renal proximal tubules from WT mice but not from PT NEMO deficient mice. Taken together, our studies suggest that renal PT NEMO plays a critical role in ischemic AKI by promoting renal tubular inflammation, apoptosis as well as necrosis.

Authors

Sang Jun Han, Ryan M. williams, Mihwa Kim, Daniel A. Heller, Vivette D'Agati, Marc Schmidt-Supprian, H. Thomas Lee

Selective inhibition of arginase-2 in endothelial cells but not proximal tubules reduces renal fibrosis

• Text
• PDF

Abstract

Fibrosis is the final common pathway in the pathophysiology of most forms of chronic kidney disease (CKD). As treatment of renal fibrosis still remains largely supportive, a refined understanding of the cellular and molecular mechanisms of kidney fibrosis and the development of novel compounds are urgently needed. Whether arginases play a role in development of fibrosis in CKD is unclear. We hypothesize that endothelial-arginase-2 (Arg2) promotes the development of kidney fibrosis induced by unilateral ureteral obstruction (UUO). Arg2 expression and arginase activity significantly increased following renal fibrosis. Pharmacological blockade or genetic deficiency of Arg2 conferred kidney protection following renal fibrosis as reflected by a reduction in kidney interstitial fibrosis and fibrotic markers. Selective deletion of Arg2 in endothelial cells (Tie2Cre/Arg2flox/flox) reduced the level of fibrosis after UUO. In contrast, selective deletion of Arg2 specifically in proximal tubular cells (Ggt1Cre/Arg2flox/flox) failed to reduce renal fibrosis after UUO. Furthermore, arginase inhibition restored kidney nitric oxide (NO) levels, oxidative stress, and mitochondrial function following UUO.These findings indicate that endothelial-Arg2 plays a major role in renal fibrosis via its action on NO and mitochondrial function. Blocking Arg2 activity or expression could be a novel therapeutic approach for prevention of CKD.

Authors

Michael Wetzel, Kristen Stanley, Wei Wei Wang, Soumya Maity, Muniswamy Madesh, W. Brian Reeves, Alaa S. Awad

Rescuing AAV gene transfer from neutralizing antibodies with an IgG-degrading enzyme

• Text
• PDF

Abstract

Pre-existing humoral immunity to recombinant adeno-associated viral (AAV) vectors restricts the treatable patient population and efficacy of human gene therapies. Approaches to clear neutralizing antibodies (NAbs), such as plasmapheresis and immunosuppression are either ineffective or cause undesirable side effects. Here, we describe a clinically relevant strategy to rapidly and transiently degrade NAbs prior to AAV administration using an IgG degrading enzyme (IdeZ). We demonstrate that recombinant IdeZ efficiently cleaves IgG in dog, monkey and human antisera. Prophylactically administered IdeZ cleaves circulating, human IgG in mice and prevents AAV neutralization in vivo. In macaques, a single intravenous dose of IdeZ rescues AAV transduction by transiently reversing seropositivity. Importantly, IdeZ efficiently cleaves NAbs and rescues AAV transduction in mice passively immunized with individual human donor sera representing a diverse population. Our antibody clearance approach presents a new paradigm for expanding the prospective patient cohort and improving efficacy of AAV gene therapy.

Authors

Zachary C. Elmore, Daniel K. Oh, Katherine E. Simon, Marco M. Fanous, Aravind Asokan

Exercise intolerance and rapid skeletal muscle energetic decline in human age-associated frailty

• Text
• PDF

Abstract

Background: Physical frailty in older individuals is characterized by subjective symptoms of fatigue and exercise intolerance (EI). Objective abnormalities in skeletal muscle (SM) mitochondrial high-energy phosphate (HEP) metabolism contribute to EI in inherited myopathies, but their presence or link to EI in the frail older adult is unknown. Methods: Three groups of ambulatory, community-dwelling adults with no history of significant coronary disease were studied: frail, older individuals (FO, 81±2.7 years, mean±SEM), non-frail, older individuals (NFO, 79±2.0 years), and healthy middle-aged controls (CONT, 51±2.1 years). Lower extremity SM HEP levels and mitochondrial function were measured with 31P magnetic resonance (MR) techniques during graded, multistage plantar flexion exercise (PFE). EI was quantified by six-minute walk and peak oxygen consumption during cardiopulmonary testing (peak-VO2). Results: During graded exercise, frail older (FO), non-frail older (NFO), and healthy middle-aged individuals all fatigued at similar SM HEP levels measured by 31P MR. However, FO fatigued fastest with several-fold higher rates of PFE-induced HEP decline, which correlated closely with shorter exercise duration in the MR scanner and with six-minute walk distance and lower peak oxygen consumption on cardiopulmonary testing (p<0.001 for all). SM mitochondrial oxidative capacity was lower in older individuals and correlated with rapid HEP decline but less closely with EI. Conclusions: Several-fold faster skeletal muscle energetic decline during exercise occurs in frail older individuals and correlates closely with multiple measures of EI. Rapid energetic decline represents an objective, functional measure of SM metabolic changes and a potential new target for mitigating frailty-associated physical limitations.

Authors

Sabra C. Lewsey, Kilian Weiss, Michael Schär, Yi Zhang, Paul A. Bottomley, T. Jake Samuel, Qian-Li Xue, Angela Steinberg, Jeremy Walston, Gary Gerstenblith, Robert G. Weiss

High levels of SARS-CoV-2 specific T-cells with restricted functionality in severe course of COVID-19

• Text
• PDF

Abstract

Background: Patients infected with SARS-CoV-2 differ in the severity of disease. We hypothesized that characteristics of SARS-CoV-2 specific immunity correlate with disease severity. Methods: In this study, SARS-CoV-2 specific T-cells and antibodies were characterized in uninfected controls and patients with different COVID-19 related disease severity. SARS-CoV-2 specific T-cells were flow-cytometrically quantified after stimulation with SARS-CoV-2 peptide pools and analyzed for expression of cytokines (IFNγ, IL-2 and TNFα) and markers for activation, proliferation and functional anergy. SARS-CoV-2 specific IgG and IgA antibodies were quantified using ELISA. Moreover, global characteristics of lymphocyte subpopulations were compared between patient groups and uninfected controls Results: Despite severe lymphopenia affecting all major lymphocyte subpopulations, patients with severe disease mounted significantly higher levels of SARS-CoV-2 specific T-cells as compared to convalescent individuals. SARS-CoV-2 specific CD4 T-cells dominated over CD8 T-cells and closely correlated with the number of plasmablasts and SARS-CoV-2 specific IgA- and IgG-levels. Unlike in convalescents, SARS-CoV-2 specific T-cells in patients with severe disease showed marked alterations in phenotypical and functional properties, which also extended to CD4 and CD8 T-cells in general. Conclusion: Given the strong induction of specific immunity to control viral replication in patients with severe disease, the functionally altered characteristics may result from the need for contraction of specific and general immunity to counteract excessive immunopathology in the lung. Trial registration: n.a. Funding: The study was supported by institutional funds by M.S., and in part by grants of Saarland University (to M.S. and. R.B), the State of Saarland, and the Dr. Rolf M. Schwiete Stiftung to R.B.

Authors

David Schub, Verena Klemis, Sophie Schneitler, Janine Mihm, Philipp M. Lepper, Heinrike Wilkens, Robert Bals, Hermann Eichler, Barbara C. Gärtner, Sören L. Becker, Urban Sester, Martina Sester, Tina Schmidt