Macrophages are main effectors of heme metabolism, increasing transiently in the liver during heightened disposal of damaged or senescent red blood cells (sRBC). Macrophages are also essential in defense against microbial threats, but pathologic states of heme excess may be immunosuppressive. Herein, we uncovered a mechanism whereby an acute rise in sRBC disposal by macrophages led to an immunosuppressive phenotype following intrapulmonary Klebsiella pneumoniae infection characterized by increased extrapulmonary bacterial proliferation and reduced survival from sepsis in mice. The impaired immunity to K. pneumoniae during heightened sRBC disposal was independent of iron acquisition by bacterial siderophores, as K. pneumoniae mutant lacking siderophore function recapitulated findings observed with wildtype strain. Rather, sRBC disposal induced a liver transcriptomic profile notable for suppression of Stat1 and interferon-related responses during K. pneumoniae sepsis. Excess heme handling by macrophages recapitulated STAT1 suppression during infection that required synergistic NRF1 and NRF2 activation but was independent of heme oxygenase-1 induction. Whereas iron was dispensable, the porphyrin moiety of heme was sufficient to mediate suppression of STAT1-dependent responses in human and mouse macrophages and promoted liver dissemination of K. pneumoniae in vivo. Thus, cellular heme metabolism dysfunction negatively regulates the STAT1 pathway with implications in severe infection.
Tolani F. Olonisakin, Tomeka L. Suber, Shekina Gonzalez-Ferrer, Zeyu Xiong, Hernán F. Peñaloza, Rick van der Geest, Yuting Xiong, David O. Osei-Hwedieh, Jesus Tejero, Matthew R. Rosengart, Wendy M. Mars, Daria Van Tyne, Andreas Perlegas, Samuel Brashears, Daniel B. Kim-Shapiro, Mark T. Gladwin, Michael A. Bachman, Eldad A. Hod, Claudette St. Croix, Yulia Y. Tyurina, Valerian E. Kagan, Rama K. Mallampalli, Anuradha Ray, Prabir Ray, Janet S. Lee
BACKGROUND. The ABO histo-blood group is defined by carbohydrate modifications and is associated with risk for multiple diseases including Acute Respiratory Distress Syndrome (ARDS). We hypothesized that genetically determined blood subtype A1 is associated with increased risk of ARDS and markers of microvascular dysfunction and coagulation. METHODS. We conducted analyses in three cohorts of critically ill trauma and sepsis patients (n = 3,710) genotyped on genome-wide platforms to determine the association of the A1 blood type genotype with ARDS risk. We subsequently determined if associations were present in FUT2 defined non-secretors who lack ABO antigens on epithelium, but not endothelium. In a patient subgroup, we determined the associations of blood type with plasma levels of endothelial glycoproteins and disseminated intravascular coagulation (DIC). Lastly, we tested if blood type A was associated with less donor lung injury recovery during human ex vivo lung perfusion (EVLP). RESULTS. The A1 genotype was associated with a higher risk of moderate to severe ARDS relative to type O in all three populations. In sepsis, this relationship was strongest in non-pulmonary infections. The association persisted in non-secretors, suggesting a vascular mechanism. The A1 genotype was also associated with higher DIC risk as well as concentrations of thrombomodulin and von Willebrand Factor, which in turn were associated with ARDS risk. Blood type A was also associated with less lung injury recovery during EVLP. CONCLUSIONS. We identified a replicable association between ABO blood type A1 and risk of ARDS among the critically ill possibly mediated through microvascular dysfunction and coagulation.
John P. Reilly, Nuala J. Meyer, Michael G.S. Shashaty, Brian J. Anderson, Caroline Ittner, Thomas G. Dunn, Brian Lim, Caitlin Forker, Michael P. Bonk, Ethan D. Kotloff, Rui Feng, Edward Cantu, Nilam S. Mangalmurti, Carolyn S. Calfee, Michael A. Matthay, Carmen Mikacenic, Keith R. Walley, James A. Russell, David C. Christiani, Mark M. Wurfel, Paul N. Lanken, Muredach P. Reilly, Jason D. Christie
Antibodies targeting human leukocyte antigen (HLA)/major histocompatibility complex (MHC) proteins limit successful transplantation and transfusion, and their presence in blood products can cause lethal transfusion-related acute lung injury (TRALI). It is unclear which cell types are bound by these ‘anti-leukocyte’ antibodies to initiate an immunologic cascade resulting in lung injury. We therefore conditionally removed MHC class I (MHC I) from likely cellular targets in antibody-mediated lung injury. Only the removal of endothelial MHC I reduced lung injury and mortality, related mechanistically to absent endothelial complement fixation and lung platelet retention. Restoration of endothelial MHC I rendered MHC I-deficient mice susceptible to lung injury. Neutrophil responses, including neutrophil extracellular trap (NET) release, were intact in endothelial MHC I-deficient mice, whereas complement depletion reduced both lung injury and NETs. Human pulmonary endothelial cells showed high HLA class I expression, and post-transfusion complement activation was increased in clinical TRALI. These results indicate that the critical source of antigen for ‘anti-leukocyte’ antibodies is in fact the endothelium, which reframes our understanding of TRALI as a rapid-onset vasculitis. Inhibition of complement activation may have multiple beneficial effects of reducing endothelial injury, platelet retention, and NET release in conditions where antibodies trigger these pathogenic responses.
Simon J. Cleary, Nicholas Kwaan, Jennifer J. Tian, Daniel R. Calabrese, Beñat Mallavia, Mélia Magnen, John R. Greenland, Anatoly Urisman, Jonathan P. Singer, Steven R. Hays, Jasleen Kukreja, Ariel M. Hay, Heather L. Howie, Pearl Toy, Clifford A. Lowell, Craig N. Morrell, James C. Zimring, Mark R. Looney
Mothers living near high-traffic roads before or during pregnancy have increased odds of having children with asthma. Mechanisms are unknown. Using a mouse model, here we showed that maternal exposure to diesel exhaust particles (DEP) predisposed offspring to allergic airway disease/AAD (murine counterpart of human asthma) through programming of their NK cells; predisposition to AAD did not develop in ‘DEP’ pups that lacked NK cells and was induced in normal pups receiving NK cells from wild type ‘DEP’ pups. “DEP’ NK cells expressed GATA3 and co-secreted IL-13 and the ‘killer’ protease granzyme B in response to allergen challenge. Extracellular granzyme B did not kill but instead it stimulated protease-activated receptor 2 (PAR2) to cooperate with IL-13 in the induction of IL-25 in airway epithelial cells. Through loss-of-function and reconstitution experiments in pups, we showed that NK cells and granzyme B were required for IL-25 induction and activation of the type-2 immune response, and IL-25 mediated NK cell effects on type-2 response and AAD. Lastly, experiments using human cord blood and airway epithelial cells suggested that DEP might induce an identical pathway in humans. Collectively, we described an NK cell-dependent endotype of AAD that emerged in early life as a result of maternal exposure to DEP.
Qian Qian, Bidisha Paul Chowdhury, Zehua Sun, Jerica Lenberg, Rafeul Alam, Eric Vivier, Magdalena M. Gorska
Allergic asthma is mediated by T helper 2 (Th2) responses to inhaled allergens. Although previous experiments indicated that Notch signaling activates expression of the key Th2 transcription factor Gata3, it remains controversial how Notch promotes allergic airway inflammation. Here we show that T cell-specific Notch deficiency in mice prevented house dust mite-driven eosinophilic airway inflammation and significantly reduced Th2 cytokine production, serum IgE levels and airway hyperreactivity. However, transgenic Gata3 overexpression in Notch-deficient T cells only partially rescued this phenotype. We found that Notch signaling was not required for T cell proliferation or Th2 polarization. Instead, Notch-deficient in vitro polarized Th2 cells showed reduced accumulation in the lungs upon in vivo transfer and allergen challenge, as Notch-deficient Th2 cells were retained in the lung draining lymph nodes. Transcriptome analyses and sequential adoptive transfer experiments revealed that while Notch-deficient lymph node Th2 cells established competence for lung migration, they failed to upregulate the sphingosine 1-phosphate receptor (S1PR1) and its critical upstream transcriptional activator Krüppel-like factor 2 (KLF2). As this KLF2-S1PR1 axis represents the essential cell-intrinsic regulator of T cell lymph node egress, we conclude that the druggable Notch signaling pathway licenses the Th2 response in allergic airway inflammation via promoting lymph node egress.
Irma Tindemans, Anne van Schoonhoven, Alex KleinJan, Marjolein J.W. de Bruijn, Melanie Lukkes, Menno van Nimwegen, Anouk van den Branden, Ingrid M. Bergen, Odilia B. J. Corneth, Wilfred F.J. van IJcken, Ralph Stadhouders, Rudi W. Hendriks
Neutrophilic inflammation is central to disease pathogenesis, e.g. in chronic obstructive pulmonary disease, yet the mechanisms retaining neutrophils within tissues remain poorly understood. With emerging evidence that axon guidance factors can regulate myeloid recruitment and that neutrophils can regulate expression of a class 3 Semaphorin, SEMA3F, we investigated the role of SEMA3F in inflammatory cell retention within inflamed tissues. We observed that neutrophils upregulate SEMA3F in response to pro-inflammatory mediators and following recruitment to the inflamed lung. In both zebrafish tail injury and murine acute lung injury models of neutrophilic inflammation, overexpression of SEMA3F delayed inflammation resolution with slower neutrophil migratory speeds and retention of neutrophils within the tissues. Conversely, constitutive loss of sema3f accelerated egress of neutrophils from the tail injury site in fish, whilst neutrophil specific deletion of Sema3f in mice resulted in more rapid neutrophil transit through the airways, and significantly reduced time to resolution of the neutrophilic response. Study of filamentous- (F-) actin subsequently showed SEMA3F mediated retention is associated with F-actin disassembly. In conclusion, SEMA3F signaling actively regulates neutrophil retention within the injured tissues with consequences for neutrophil clearance and inflammation resolution.
Tracie Plant, Suttida Eamsamarng, Manuel A. Sanchez-Garcia, Leila Reyes, Stephen A. Renshaw, Patricia Coelho, Ananda S. Mirchandani, Jessie-May Morgan, Felix E. Ellett, Tyler Morrison, Duncan Humphries, Emily R. Watts, Fiona Murphy, Ximena L. Raffo-Iraolagoitia, Ailiang Zhang, Jenna L. Cash, Catherine Loynes, Philip M. Elks, Freek Van Eeden, Leo M. Carlin, Andrew J. W. Furley, Moira K. B. Whyte, Sarah R. Walmsley
Cystic fibrosis (CF) lung disease is characterized by an inflammatory response that can lead to terminal respiratory failure. The cystic fibrosis transmembrane regulator (CFTR) is mutated in CF and we hypothesized that dysfunctional CFTR in platelets, which are key participants in immune responses, is a central determinant of CF inflammation. We found that deletion of CFTR in platelets produced exaggerated acute lung inflammation and platelet activation after intratracheal LPS or Pseudomonas aeruginosa challenge. CFTR loss of function in mouse or human platelets resulted in agonist-induced hyperactivation and increased calcium entry into platelets. Inhibition of the transient receptor potential cation channel 6 (TRPC6) reduced platelet activation and calcium flux, and reduced lung injury in CF mice after intratracheal LPS or Pseudomonas aeruginosa challenge. CF subjects receiving CFTR modulator therapy showed partial restoration of CFTR function in platelets, which may be a convenient approach to monitoring biological responses to CFTR modulators. We conclude that CFTR dysfunction in platelets produces aberrant TRPC6-dependent platelet activation, which is a major driver of CF lung inflammation and impaired bacterial clearance. Platelets, and TRPC6, are what we believe to be novel therapeutic targets in the treatment of CF lung disease.
Guadalupe Ortiz-Munoz, Michelle A. Yu, Emma Lefrançais, Benat Mallavia, Colin Valet, Jennifer J. Tian, Serena Ranucci, Kristin M. Wang, Zhe Liu, Nicholas Kwaan, Diana Dawson, Mary Ellen Kleinhenz, Fadi T. Khasawneh, Peter M. Haggie, Alan S. Verkman, Mark R. Looney
Risk for childhood asthma is conferred by alleles within the 17q21 locus affecting ORMDL sphingolipid biosynthesis regulator 3 (ORMDL3) expression. ORMDL3 inhibits sphingolipid de novo synthesis. Although the effects of 17q21 genotypes on sphingolipid synthesis in human asthma remain unclear, both decreased sphingolipid synthesis and ORMDL3 overexpression are linked to airway hyperreactivity. To characterize the relationship of genetic asthma susceptibility with sphingolipid synthesis, we analyzed asthma-associated 17q21 genotypes (rs7216389, rs8076131, rs4065275, rs12603332, and rs8067378) in both children with asthma and those without asthma, quantified plasma and whole-blood sphingolipids, and assessed sphingolipid de novo synthesis in peripheral blood cells by measuring the incorporation of stable isotope–labeled serine (substrate) into sphinganine and sphinganine-1-phosphate. Whole-blood dihydroceramides and ceramides were decreased in subjects with the 17q21 asthma–risk alleles rs7216389 and rs8076131. Children with nonallergic asthma had lower dihydroceramides, ceramides, and sphingomyelins than did controls. Children with allergic asthma had higher dihydroceramides, ceramides, and sphingomyelins compared with children with nonallergic asthma. Additionally, de novo sphingolipid synthesis was lower in children with asthma compared with controls. These findings connect genetic 17q21 variations that are associated with asthma risk and higher ORMDL3 expression to lower sphingolipid synthesis in humans. Altered sphingolipid synthesis may therefore be a critical factor in asthma pathogenesis and may guide the development of future therapeutics.
Jennie G. Ono, Benjamin I. Kim, Yize Zhao, Paul J. Christos, Yohannes Tesfaigzi, Tilla S. Worgall, Stefan Worgall
Influenza A virus (IAV) is among the most common causes of pneumonia related death worldwide. Pulmonary epithelial cells are the primary target for viral infection and replication and respond by releasing inflammatory mediators that recruit immune cells to mount the host response. Severe lung injury and death during IAV infection results from an exuberant host inflammatory response. The linear ubiquitin assembly complex (LUBAC), composed of SHARPIN, HOIL-1L and HOIP, is a critical regulator of NF-κB-dependent inflammation. Using mice with lung epithelial specific deletions of HOIL-1L or HOIP in a model of IAV infection, we provided evidence that, while a reduction in the inflammatory response was beneficial, ablation of the LUBAC-dependent lung epithelial-driven response worsened lung injury and increased mortality. Moreover, we described a mechanism for the upregulation of HOIL-1L in infected and non-infected cells triggered by the activation of type I interferon receptor and mediated by IRF1, which was maladaptive and contributed to hyper-inflammation. Thus, we propose that lung epithelial LUBAC acts as a molecular rheostat that could be selectively targeted to modulate the immune response in patients with severe IAV-induced pneumonia.
Patricia L. Brazee, Luisa Morales-Nebreda, Natalia D. Magnani, Joe G.N. Garcia, Alexander V. Misharin, Karen M. Ridge, G.R. Scott Budinger, Kazuhiro Iwai, Laura A. Dada, Jacob I. Sznajder
Antagonists of the type 1 cysteinyl leukotriene receptor (CysLT1R) are widely used to treat asthma and allergic rhinitis, with variable response rates. Alveolar macrophages express UDP-specific P2Y6 receptors that can be blocked by off-target effects of CysLT1R antagonists. Sensitizing intranasal doses of an extract from the house dust mite Dermatophagoides farinae (Df) sharply increased the levels of UDP detected in bronchoalveolar lavage fluid of mice. Conditional deletion of P2Y6 receptors before sensitization exacerbated eosinophilic lung inflammation and type 2 cytokine production in response to subsequent Df challenge. P2Y6 receptor signaling was necessary for dectin-2–dependent production of protective IL-12p40 and Th1 chemokines by alveolar macrophages, leading to activation of NK cells to generate IFN-γ. Administration of CysLT1R antagonists during sensitization blocked UDP-elicited potentiation of IL-12p40 production by macrophages in vitro, suppressed the Df-induced production of IL-12p40 and IFN-γ in vivo, and suppressed type 2 inflammation only in P2Y6-deficient mice. Thus, P2Y6 receptor signaling drives an innate macrophage/IL-12/NK cell/IFN-γ axis that prevents inappropriate allergic type 2 immune responses on respiratory allergen exposure and counteracts the Th2 priming effect of CysLT1R signaling at sensitization. Targeting P2Y6 signaling might prove to be a potential additional treatment strategy for allergy.
Jun Nagai, Barbara Balestrieri, Laura B. Fanning, Timothy Kyin, Haley Cirka, Junrui Lin, Marco Idzko, Andreas Zech, Edy Y. Kim, Patrick J. Brennan, Joshua A. Boyce