Immunology
Abstract
Some effector CD4+ T cell subsets display cytotoxic activity, thus breaking the functional dichotomy of CD4+ helper and CD8+ cytotoxic T lymphocytes. However, molecular mechanisms regulating CD4+ cytotoxic T lymphocyte (CD4+ CTL) differentiation are poorly understood. Here we show that levels of histone deacetylases 1 and 2 (HDAC1-HDAC2) are key determinants of CD4+ CTL differentiation. Deletions of both Hdac1 and 1 Hdac2 alleles (HDAC1cKO-HDAC2HET) in CD4+ T cells induced a T helper cytotoxic program that was controlled by IFN-γ–JAK1/2–STAT1 signaling. In vitro, activated HDAC1cKO-HDAC2HET CD4+ T cells acquired cytolytic activity and displayed enrichment of gene signatures characteristic of effector CD8+ T cells and human CD4+ CTLs. In vivo, murine cytomegalovirus–infected HDAC1cKO-HDAC2HET mice displayed a stronger induction of CD4+ CTL features compared with infected WT mice. Finally, murine and human CD4+ T cells treated with short-chain fatty acids, which are commensal-produced metabolites acting as HDAC inhibitors, upregulated CTL genes. Our data demonstrate that HDAC1-HDAC2 restrain CD4+ CTL differentiation. Thus, HDAC1-HDAC2 might be targets for the therapeutic induction of CD4+ CTLs.
Authors
Teresa Preglej, Patricia Hamminger, Maik Luu, Tanja Bulat, Liisa Andersen, Lisa Göschl, Valentina Stolz, Ramona Rica, Lisa Sandner, Darina Waltenberger, Roland Tschismarov, Thomas Faux, Thorina Boenke, Asta Laiho, Laura L. Elo, Shinya Sakaguchi, Günter Steiner, Thomas Decker, Barbara Bohle, Alexander Visekruna, Christoph Bock, Birgit Strobl, Christian Seiser, Nicole Boucheron, Wilfried Ellmeier
Abstract
Neutrophils are the most abundant inflammatory cells at the earliest stages of wound healing and play important roles in wound repair and fibrosis. Formyl peptide receptor 1 (FPR-1) is abundantly expressed on neutrophils and has been shown to regulate their function, yet the importance of FPR-1 in fibrosis remains ill defined. FPR-1–deficient (fpr1–/–) mice were protected from bleomycin-induced pulmonary fibrosis but developed renal and hepatic fibrosis normally. Mechanistically, we observed a failure to effectively recruit neutrophils to the lungs of fpr1–/– mice, whereas neutrophil recruitment was unaffected in the liver and kidney. Using an adoptive transfer model we demonstrated that the defect in neutrophil recruitment to the lung was intrinsic to the fpr1–/– neutrophils, as C57BL/6 neutrophils were recruited normally to the damaged lung in fpr1–/– mice. Finally, C57BL/6 mice in which neutrophils had been depleted were protected from pulmonary fibrosis. In conclusion, FPR-1 and FPR-1 ligands are required for effective neutrophil recruitment to the damaged lung. Failure to recruit neutrophils or depletion of neutrophils protects from pulmonary fibrosis.
Authors
Jack Leslie, Ben J.M. Millar, Alicia del Carpio Pons, Rachel A. Burgoyne, Joseph D. Frost, Ben S. Barksby, Saimir Luli, Jon Scott, A. John Simpson, Jack Gauldie, Lynne A. Murray, Donna K. Finch, Alan M. Carruthers, John Ferguson, Matthew A. Sleeman, David Rider, Rachel Howarth, Christopher Fox, Fiona Oakley, Andrew J. Fisher, Derek A. Mann, Lee A. Borthwick
Abstract
The specificity of antibodies (Abs) generated to influenza A virus (IAV) infection can significantly alter protection and viral clearance. At present, the impact of age upon this process is relatively unexplored. Here, we evaluated the Ab response in newborn and adult African green monkeys (AGM) following infection with IAV using a strain that enables us to determine the immunodominance (ID) hierarchy of the Ab response to hemagglutinin (HA), the principal target of protective Abs. This revealed altered ID patterns in the early IgM anti-HA response in newborns versus adults that converged over time. While the IgG ID profiles for HA in newborn and adult monkeys were similar, this was not the case for IgA. Importantly, HA stem-specific Abs were generated robustly and similarly in newborns and adults in terms of quality and quantity. Together these results demonstrate that newborns and adults can differ in the Ab ID pattern established following infection and that the ID pattern can vary across isotypes. In addition, newborns have the ability to generate potent HA stem-specific Ab responses. Our findings further the understanding of the newborn response to IAV antigens and inform the development of improved vaccines for this at-risk population.
Authors
Elene A. Clemens, Davide Angeletti, Beth C. Holbrook, Masaru Kanekiyo, Matthew J. Jorgensen, Barney S. Graham, Jonathan W. Yewdell, Martha A. Alexander-Miller
Abstract
A critical component of wound healing is the transition from the inflammatory phase to the proliferation phase to initiate healing and remodeling of the wound. Macrophages are critical for the initiation and resolution of the inflammatory phase during wound repair. In diabetes, macrophages display a sustained inflammatory phenotype in late wound healing characterized by elevated production of inflammatory cytokines such as TNFα. Previous studies have shown that an altered epigenetic program directs diabetic macrophages towards a pro-inflammatory phenotype contributing to a sustained inflammatory phase. Males absent on the first (MOF) is a histone acetyl-transferase (HAT) that has been shown be a co-activator of TNFα-signaling and promote NFκB-mediated gene transcription in prostate cancer cell lines. Based on MOFs role in TNFα/NFκB-mediated gene expression, we hypothesized that MOF influences macrophage-mediated inflammation during wound repair. We used a myeloid-specific Mof knockout (Lyz2Cre Moff/f) and diet-induced obese (DIO) mice, to determine the function of MOF in diabetic wound healing. MOF deficient mice exhibited reduced inflammatory cytokine gene expression. Furthermore, we found that wound macrophages from DIO mice had elevated MOF levels and higher levels of acetylated histone H4K16, MOFs primary substrate of HAT activity, on the promoters of inflammatory genes. We further identified that MOF expression could by stimulated by TNFα and that treatment with Etanercept, an FDA-approved TNFα inhibitor, reduced MOF levels and improved wound healing in DIO mice. This report is the first to define an important role for MOF in regulating macrophage-mediated inflammation in wound repair and identifies TNFα-inhibition as a potential therapy for the treatment of chronic inflammation in diabetic wounds.
Authors
Aaron D. denDekker, Frank M. Davis, Amrita D. Joshi, Sonya J. Wolf, Ronald Allen, Jay Lipinski, Brenda Nguyen, Joseph Kirma, Dylan Nycz, Jennifer R. Bermick, Bethany B. Moore, Johann E. Gudjonsson, Steven L. Kunkel, Katherine A. Gallagher
Abstract
Acute kidney injury (AKI) and chronic kidney diseases are associated with high mortality and morbidity. Although the underlying mechanisms determining the transition from acute to chronic injury are not completely understood, immune-mediated processes are critical in renal injury. We have performed a comparison of 2 mouse models leading to either kidney regeneration or fibrosis. Using global gene expression profiling we could identify immune-related pathways accounting for the majority of the observed transcriptional changes during fibrosis. Unbiased examination of the immune cell composition, using single-cell RNA sequencing, revealed major changes in tissue-resident macrophages and T cells. Following injury, there was a marked increase in tissue-resident IL-33R+ and IL-2Ra+ regulatory T cells (Tregs). Expansion of this population before injury protected the kidney from injury and fibrosis. Transcriptional profiling of Tregs showed a differential upregulation of regenerative and proangiogenic pathways during regeneration, whereas in the fibrotic environment they expressed markers of hyperactivation and fibrosis. Our data point to a hitherto underappreciated plasticity in Treg function within the same tissue, dictated by environmental cues. Overall, we provide a detailed cellular and molecular characterization of the immunological changes during kidney injury, regeneration, and fibrosis.
Authors
Fernanda do Valle Duraes, Armelle Lafont, Martin Beibel, Kea Martin, Katy Darribat, Rachel Cuttat, Annick Waldt, Ulrike Naumann, Grazyna Wieczorek, Swann Gaulis, Sabina Pfister, Kirsten D. Mertz, Jianping Li, Guglielmo Roma, Max Warncke
Abstract
IL-17A plays a critical role in the pathogenesis of steroid-resistant neutrophilic airway inflammation, which is a hallmark of severe asthma and chronic obstructive pulmonary disease (COPD). Through RNA sequencing analysis of transcriptomes of human airway smooth muscle cells treated with IL-17A, dexamethasone (DEX, a synthetic glucocorticoid drug), alone or in combination, we identified a group of genes that are synergistically induced by IL-17A and DEX, including the neutrophil-promoting cytokine CSF3. In type-17 (Th17/IL-17Ahi) preclinical models of neutrophilic severe asthma (acute and chronic) and COPD, although DEX treatment was able to reduce the expression of neutrophil-mobilizing CXCL1 and CXCL2 in lung tissue, CSF3 expression was upregulated by DEX treatment. We found that DEX treatment alone failed to alleviate neutrophilic airway inflammation and pathology, and even exacerbated the disease phenotype when CSF3 was highly induced. Disruption of the IL-17A/DEX synergy by IL-17A inhibition with anti–IL-17A mAb or cyanidin-3-glucoside (C3G, a small-molecule IL-17A blocker) or depletion of CSF3 effectively rendered DEX sensitivity in type-17 preclinical models of neutrophilic airway diseases. Our study elucidates what we believe is a novel mechanism of steroid resistance in type-17 neutrophilic airway inflammation and offers an effective steroid-sparing therapeutic strategy (combined low-dose DEX and C3G) for treating neutrophilic airway diseases.
Authors
Suidong Ouyang, Caini Liu, Jianxin Xiao, Xing Chen, Andy C. Lui, Xiaoxia Li
Abstract
Altered bone marrow hematopoiesis and immune suppression is a hallmark of myelodysplastic syndrome (MDS). While the bone marrow microenvironment influences malignant hematopoiesis, the mechanism leading to MDS-associated immune suppression is unknown. We tested whether mesenchymal stromal cells (MSCs) contribute to this process. Here, we developed a model to study cultured MSCs from MDS patients compared to similar aged matched normal controls for regulation of immune function. MSCs from MDS patients (MDS-MSC) and healthy donor MSC (HD-MSC) exhibited a similar in vitro phenotype and neither had a direct effect on NK cell function. However, when MDS and HD-MSCs were cultured with monocytes, only the MDS-MSCs acquired phenotypic and metabolic properties of myeloid-derived suppressor cells (MDSCs), with resulting suppression of NK cell function, along with T cell proliferation. A unique MSC transcriptome was observed in MDS-MSCs compared to HD-MSCs, including increased expression of the reactive oxygen species (ROS) regulator, ENC1. High ENC1 expression in MDS-MSC induced suppressive monocytes with increased INHBA, a gene that encodes for a member of the TGFβ superfamily of proteins. These monocytes also had reduced expression of the TGFβ transcriptional repressor MAB21L2, further adding to their immune suppressive function. Silencing ENC1 or inhibiting ROS production in MDS-MSCs abrogated the suppressive function of MDS-MSC conditioned monocytes. In addition, silencing MAB21L2 in healthy MSC conditioned monocytes mimicked the MDS-MSC suppressive transformation of monocytes. Our data demonstrate that MDS-MSCs are responsible for inducing an immune suppressive microenvironment in MDS through an indirect mechanism involving monocytes.
Authors
Dhifaf Sarhan, Jinhua Wang, Upasana Sunil Arvindam, Caroline Hallstrom, Michael R. Verneris, Bartosz Grzywacz, Erica Warlick, Bruce R. Blazar, Jeffrey S. Miller
Abstract
Extracellular cold-inducible RNA-binding protein (eCIRP) is a recently-discovered damage-associated molecular pattern. Understanding the precise mechanism by which it exacerbates inflammation is essential. Here we identified that eCIRP is a new biologically active endogenous ligand of triggering receptor expressed on myeloid cells-1 (TREM-1), fueling inflammation in sepsis. Surface plasmon resonance revealed a strong binding affinity between eCIRP and TREM-1, and FRET assay confirmed eCIRP’s interaction with TREM-1 in macrophages. Targeting TREM-1 by its siRNA or a decoy peptide LP17 or by using TREM-1-/- mice dramatically reduced eCIRP-induced inflammation. We developed a novel 7-aa peptide derived from human eCIRP, M3, which blocked the interaction of TREM-1 and eCIRP. M3 suppressed inflammation induced by eCIRP or agonist TREM-1 Ab crosslinking in murine macrophages or human peripheral blood monocytes. M3 also inhibited eCIRP-induced systemic inflammation and tissue injury. Treatment with M3 further protected mice from sepsis, improved acute lung injury, and increased survival. Thus, we have discovered a novel TREM-1 ligand and developed a new peptide M3 to block the eCIRP-TREM-1 interaction and improve the outcomes in sepsis.
Authors
Naomi-Liza Denning, Monowar Aziz, Atsushi Murao, Steven D. Gurien, Mahendar Ochani, Jose M. Prince, Ping Wang
Abstract
Extracellular cold-inducible RNA-binding protein (eCIRP) is a damage-associated molecular pattern, whose effect on macrophages is not entirely elucidated. Here we identified that eCIRP promotes macrophage endotoxin tolerance. Septic mice had higher serum levels of eCIRP; this was associated with a reduced ex vivo immune response of their splenocytes to LPS. Pretreatment of macrophages with recombinant murine (rm) CIRP resulted in a tolerance to LPS stimulation as demonstrated by a significant reduction of TNF-α production. We found that eCIRP increased phosphorylation of STAT3 (pSTAT3) in macrophages. A STAT3 inhibitor, Stattic, rescued macrophages from rmCIRP-induced tolerance by restoring the release of TNF-α in response to LPS stimulation. We discovered strong binding affinity between eCIRP and IL-6R as revealed by Biacore, FRET, and their co-localization in macrophages by immunostaining assays. Blockade of IL-6R with its neutralizing Ab significantly inhibited eCIRP-induced pSTAT3 and restored LPS-stimulated TNF-α release in macrophages. Incubation of macrophages with rmCIRP skewed them towards a M2 phenotype, while treatment with anti-IL-6R Ab prevented rmCIRP-induced M2 polarization. Thus, we have demonstrated that eCIRP activates pSTAT3 via a novel receptor IL-6R to promote macrophage endotoxin tolerance. Targeting eCIRP appears to be a new therapeutic option to correct immune-tolerance in sepsis.
Authors
Mian Zhou, Monowar Aziz, Naomi-Liza Denning, Hao-Ting Yen, Gaifeng Ma, Ping Wang
Abstract
The HIV latent reservoir in resting memory CD4+ T cells prevents cure. Therapeutics to reactivate and eliminate this reservoir are in clinical trials in adults, but not in pediatric populations. We determined, ex vivo, the inducibility and size of the latent reservoir in perinatal compared with adult infections using the Tat/rev Induced Limiting Dilution Assay (TILDA), in which a single-round (12hr) of CD4+ T cell stimulation with PMA/ionomycin maximally activates T cells and leads to proviral expression with multiply-spliced HIV RNA production. Markers of immune activation and exhaustion were measured to assess interactions with inducibility. Despite similar rates of T cell activation with PMA/ionomycin, the latent reservoir in perinatal infection is slower to reactivate and of lower magnitude compared to adult infection, independent of proviral load. An enhanced TILDA with the addition of phytohemagglutin and for 18 hours augmented proviral expression in perinatal but not adult infection. Baseline HLA–DR+ CD4+ T cells was significantly lower in perinatal compared with adult infections, but not correlated with induced reservoir size. These data support differences in baseline immune activation and kinetics of latency reversal in perinatal compared with adult infections, with implications for latency reversal strategies towards reservoir clearance and remission.
Authors
Adit Dhummakupt, Jessica H. Rubens, Thuy Anderson, Laura Powell, Bareng A.S. Nonyane, Lilly V. Siems, Aleisha Collinson-Streng, Tricia L. Nilles, R. Brad Jones, Vicki Tepper, Allison Agwu, Deborah Persaud
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