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Abstract
While the advent of combination antiretroviral therapy (ART) has significantly improved survival, tuberculosis (TB) remains the leading cause of death in the HIV-infected population. We employed Mtb/Simian Immunodeficiency Virus (SIV) co-infected macaques to model Mtb/HIV co-infection and study the impact of ART on TB reactivation due to HIV-infection. While ART significantly reduced viral loads and increased CD4+ T cell counts in whole blood and BAL samples, it did not reduce the relative risk of SIV- induced TB reactivation in ART treated macaques in the early phase of treatment. CD4+ T cells were poorly restored specifically in the lung interstitium, despite their significant restoration in the alveolar compartment of the lung as well as in the periphery. IDO1 induction on myeloid cells in the iBALT likely contributed to dysregulated T cell homing and impaired lung immunity. Thus, while ART is indispensable in controlling viral replication, CD4+ T cells restoration and preventing opportunistic infection, it appears inadequate in reversing clinical signs of TB reactivation during the relatively short duration of ART and follow-up during this study. This warrants modeling concurrent treatment of TB and HIV to potentially reduce the risk of reactivation of TB due to HIV. The current and future studies like this have the potential to inform treatment strategies in patients with Mtb/HIV co-infection.
Authors
Shashank R. Ganatra, Allison N. Bucsan, Xavier Alvarez, Shyamesh Kumar, Ayan Chatterjee, Melanie Quezada, Abigail I. Fish, Dhiraj K. Singh, Bindu Singh, Riti Sharan, Tae-Hyung Lee, Uma Shanmugasundaram, Vijayakumar Velu, Shabaana A. Khader, Smriti Mehra, Jyothi Rengarajan, Deepak Kaushal
Abstract
The amyloid hypothesis posits that the amyloid-beta (Aβ) protein precedes and requires microtubule-associated protein tau in a sort of trigger-bullet mechanism leading to Alzheimer’s disease (AD) pathology. This sequence of events has become dogmatic in the AD field and is used to explain clinical trial failures due to a late start of the intervention when Aβ already activated tau. Here, using a multidisplinary approach combining molecular biological, biochemical, histopathological, electrophysiological and behavioral methods we demonstrated that tau suppression did not protect against Aβ-induced damage of long-term synaptic plasticity and memory, as well as amyloid deposition. Tau suppression could even unravel a defect in basal synaptic transmission in a mouse model of amyloid deposition. Similarly, tau suppression did not protect against exogenous oligomeric tau induced impairment of long-term synaptic plasticity and memory. The protective effect of tau suppression was, in turn, confined to short-term plasticity and memory. Taken together, our data suggest that therapies downstream of Aβ and tau together are more suitable to combat AD than therapies against one or the other alone.
Authors
Daniela Puzzo, Elentina K. Argyrousi, Agnieszka Staniszewski, Hong Zhang, Elisa Calcagno, Elisa Zuccarello, Erica Acquarone, Mauro Fà, Domenica Donatella Li Puma, Claudio Grassi, Luciano D'Adamio, Nicholas M. Kanaan, Paul E. Fraser, Ottavio Arancio
Abstract
The biology of harlequin ichthyosis (HI), a devastating skin disorder, caused by loss of function mutations in the gene ABCA12, is poorly understood and to date no satisfactory treatment has been developed. We sought to investigate pathomechanisms of HI which could lead to the identification of new treatments to improve patients’ quality of life. In this study, RNA-Seq and functional assays were performed to define the effects of loss of ABCA12, using HI patient skin samples and an engineered CRISPR-Cas9 ABCA12 KO cell line. The HI living skin equivalent (3D model) recapitulated the HI skin phenotype. The cytokines IL-36α and IL-36γ were upregulated in HI skin whereas the innate immune inhibitor, IL-37, was strongly downregulated. We also identified STAT1 and its downstream target inducible nitric oxide synthase (NOS2) to be upregulated in the in vitro HI 3D model and HI patient skin samples. Inhibition of NOS2 using the inhibitor, 1400W, or the JAK inhibitor, tofacitinib, dramatically improved the in vitro HI phenotype by restoring the lipid barrier in the HI 3D model. Our study has identified dysregulated pathways in HI skin that are feasible therapeutic targets.
Authors
Florence Enjalbert, Priya Dewan, Matthew P. Caley, Eleri M. Jones, Mary A. Morse, David P. Kelsell, Anton J. Enright, Edel A. O'Toole
Abstract
Skeletal muscle depends on the precise orchestration of contractile and metabolic gene expression programs to direct fiber type specification and to ensure muscle performance. Exactly how such fiber type-specific patterns of gene expression are established and maintained remains unclear, however. Here, we demonstrate that histone mono-methyltransferase MLL4 (KMT2D), an enhancer regulator enriched in slow myofibers, plays a critical role in controlling muscle fiber identity as well as muscle performance. Skeletal muscle-specific ablation of MLL4 in mice resulted in downregulation of the slow-oxidative myofiber gene program, decreased number of type I myofibers, and diminished mitochondrial respiration, which caused reductions in muscle fat utilization and endurance capacity during exercise. Genome-wide ChIP-seq and mRNA-seq analyses revealed that MLL4 directly binds to enhancers and functions as a coactivator of the myocyte enhancer factor 2 (MEF2) to activate transcription of slow-oxidative myofiber genes. Importantly, we also found that the MLL4 regulatory circuit is associated with muscle fiber type remodeling in humans. Thus, our results uncover a pivotal role for MLL4 in specifying structural and metabolic identities of myofibers that govern muscle performance. These findings provide new therapeutic opportunities for enhancing muscle fitness to combat a variety of metabolic and muscular diseases.
Authors
Lin Liu, Chenyun Ding, Tingting Fu, Zhenhua Feng, Ji-Eun Lee, Liwei Xiao, Zhisheng Xu, Yujing Yin, Qiqi Guo, Zongchao Sun, Wanping Sun, Yan Mao, Likun Yang, Zheng Zhou, Danxia Zhou, Leilei Xu, Zezhang Zhu, Yong Qiu, Kai Ge, Zhenji Gan
Abstract
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.
Authors
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
Abstract
Cachexia, a devastating wasting syndrome characterized by severe weight loss with specific losses of muscle and adipose tissue, is driven by reduced food intake, increased energy expenditure, excess catabolism, and inflammation. Cachexia is associated with poor prognosis and high mortality, and frequently occurs in patients with cancer, chronic kidney disease, infection, and many other illnesses. There is no effective treatment for this condition. Hypothalamic melanocortins have a potent and long-lasting inhibitory effect on feeding and anabolism, and pathophysiological processes increase melanocortin signaling tone leading to anorexia, metabolic changes, and eventual cachexia. We utilized three rat models of anorexia and cachexia (LPS, methylcholanthrene sarcoma, and 5/6 subtotal nephrectomy) to evaluate efficacy of TCMCB07, a synthetic antagonist of the melanocortin-4 receptor. Our data show that peripheral treatment of TCMCB07 with intraperitoneal, subcutaneous, and oral administration increased food intake and body weight, and preserved fat mass and lean mass during cachexia and LPS-induced anorexia. Furthermore, administration of TCMCB07 diminished hypothalamic inflammatory gene expression in cancer cachexia. These results suggest that peripheral TCMCB07 treatment effectively inhibits central melanocortin signaling and therefore stimulates appetite and enhances anabolism, indicating that TCMCB07 is a promising drug candidate to treat cachexia.
Authors
Xinxia Zhu, Michael F. Callahan, Kenneth A. Gruber, Marek Szumowski, Daniel L. Marks
Abstract
BACKGROUND. Convalescent plasma is the only antibody based therapy currently available for COVID 19 patients. It has robust historical precedence and sound biological plausibility. Although promising, convalescent plasma has not yet been shown to be safe as a treatment for COVID-19. METHODS. Thus, we analyzed key safety metrics after transfusion of ABO compatible human COVID-19 convalescent plasma in 5,000 hospitalized adults with severe or life threatening COVID-19, with 66% in the intensive care unit, as part of the US FDA Expanded Access Program for COVID-19 convalescent plasma. RESULTS. The incidence of all serious adverse events (SAEs) in the first four hours after transfusion was <1%, including mortality rate (0.3%). Of the 36 reported SAEs, there were 25 reported incidences of related SAEs, including mortality (n = 4), transfusion-associated circulatory overload (TACO; n = 7), transfusion-related acute lung injury (TRALI; n = 11), and severe allergic transfusion reactions (n = 3). However, only 2 (of 36) SAEs were judged as definitely related to the convalescent plasma transfusion by the treating physician. The seven-day mortality rate was 14.9%. CONCLUSION. Given the deadly nature of COVID 19 and the large population of critically-ill patients included in these analyses, the mortality rate does not appear excessive. These early indicators suggest that transfusion of convalescent plasma is safe in hospitalized patients with COVID-19.
Authors
Michael J. Joyner, R. Scott Wright, DeLisa Fairweather, Jonathon W. Senefeld, Katelyn A. Bruno, Stephen A. Klassen, Rickey E. Carter, Allan M. Klompas, Chad C. Wiggins, John R.A. Shepherd, Robert F. Rea, Emily R. Whelan, Andrew J. Clayburn, Matthew R. Spiegel, Patrick W. Johnson, Elizabeth R. Lesser, Sarah E. Baker, Kathryn F. Larson, Juan G. Ripoll, Kylie J. Andersen, David O. Hodge, Katie L. Kunze, Matthew R. Buras, Matthew N.P. Vogt, Vitaly Herasevich, Joshua J. Dennis, Riley J. Regimbal, Philippe R. Bauer, Janis E. Blair, Camille M. van Buskirk, Jeffrey L. Winters, James R. Stubbs, Nigel S. Paneth, Nicole C. Verdun, Peter Marks, Arturo Casadevall
Abstract
Connexin 43 (Cx43) gap junctions provide intercellular coupling which ensures rapid action potential propagation and synchronized heart contraction. Altered Cx43 localization and reduced gap junction coupling occur in failing hearts, contributing to ventricular arrhythmias and sudden cardiac death. Recent reports have found that an internally translated Cx43 isoform, GJA1-20k, is an auxiliary subunit for the trafficking of Cx43 in heterologous expression systems. Here, we have created a mouse model by using CRISPR technology to mutate a single internal translation initiation site in Cx43 (M213L mutation), which generates full length Cx43 but not GJA1-20k. We find that GJA1M213L/M213L mice have severely abnormal electrocardiograms despite preserved contractile function, reduced total Cx43, reduced gap junctions, and die suddenly at two to four weeks of age. Heterozygous GJA1M213L/WT mice survive to adulthood with increased ventricular ectopy. Biochemical experiments indicate that cytoplasmic Cx43 has a half life that is 50% shorter than membrane associated Cx43. Without GJA1-20k, poorly trafficked Cx43 is degraded. The data support that GJA1-20k, an endogenous entity translated independently of Cx43, is critical for Cx43 gap junction trafficking, maintenance of Cx43 protein, and normal electrical function of the mammalian heart.
Authors
Shaohua Xiao, Daisuke Shimura, Rachel Baum, Diana M. Hernandez, Sosse Agvanian, Yoshiko Nagaoka, Makoto Katsumata, Paul D. Lampe, Andre G. Kleber, TingTing Hong, Robin M. Shaw
Abstract
Graft-versus-host-disease (GVHD) is a major cause of morbidity and mortality in hematopoietic stem cell transplantation (HSCT). Donor T cells are key mediators in pathogenesis but a contribution from host T cells has not been explored, as conditioning regimens are believed to deplete host T cells. To evaluate a potential role for host T cells in GVHD, the origin of skin and blood T cells was assessed prospectively in patients after HSCT in the absence of GVHD. While blood contained primarily donor-derived T cells, most T cells in the skin were host-derived. We next examined patient skin, colon and blood during acute GVHD. Host T cells were present in all skin and colon acute GVHD specimens studied yet were largely absent in blood. We observed acute skin GVHD in the presence of 100% host T cells. Analysis demonstrated that a subset of host T cells in peripheral tissues were proliferating (Ki67+) and producing the pro-inflammatory cytokines IFNγ and IL-17 in situ. Comparatively, the majority of antigen presenting cells (APC) in tissue in acute GVHD were donor-derived, and donor-derived APC were observed directly adjacent to host T cells. A humanized mouse model demonstrated that host skin-resident T cells could be activated by donor monocytes to generate a GVHD-like dermatitis. Thus, host tissue-resident T cells may play a previously unappreciated pathogenic role in acute GVHD.
Authors
Sherrie J. Divito, Anders T. Aasebo, Tiago R. Matos, Pei-Chen Hsieh, Matthew Collin, Christopher P. Elco, John T. O'Malley, Espen S. Bækkevold, Henrik M. Reims, Tobias Gedde-Dahl, Michael Hagerstrom, Jude Hilaire, John W. Lian, Edgar L. Milford, Geraldine S. Pinkus, Vincent T. Ho, Robert J. Soiffer, Haesook T. Kim, Martin C. Mihm Jr, Jerome Ritz, Indira Guleria, Corey S. Cutler, Rachael Clark, Frode L. Jahnsen, Thomas S. Kupper
Abstract
The tight junction protein claudin-2 is upregulated in disease. Although many studies have linked intestinal barrier loss to local and systemic disease, these have relied on macromolecular probes. In vitro analyses show however that these probes cannot be accommodated by size- and charge-selective claudin-2 channels. We sought to define the impact of claudin-2 channels on disease. Transgenic claudin-2 overexpression or IL-13-induced claudin-2 upregulation increased intestinal small cation permeability in vivo. IL-13 did not however affect permeability in claudin-2-knockout mice. Claudin-2 is therefore necessary and sufficient to effect size- and charge-selective permeability increases in vivo. In chronic disease, T-cell transfer colitis severity was augmented or diminished in claudin-2 transgenic or knockout mice, respectively. We translated in vitro data suggesting that casein kinase-2 (CK2) inhibition blocks claudin-2 channel function and found that CK2 inhibition prevented IL-13-induced, claudin-2-mediated permeability increases in vivo. In chronic immune-mediated colitis, CK2 inhibition attenuated progression in claudin-2-sufficient, but not claudin-2-knockout, mice, i.e., the effect was claudin-2-dependent. Paracellular flux mediated by claudin-2 channels can therefore promote immune-mediated colitis progression. Although the mechanisms by which claudin-2 channels intensify disease remain to be defined, these data suggest that claudin-2 may be an accessible target in immune-mediated disorders, including inflammatory bowel disease.
Authors
Preeti Raju, Nitesh Shashikanth, Pei-Yun Tsai, Pawin Pongkorpsakol, Sandra Chanez-Parades, Peter R. Steinhagen, Wei-Ting Kuo, Gurminder Singh, Sachiko Tsukita, Jerrold R. Turner
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ISSN: 0021-9738 (print), 1558-8238 (online)