RESUMEN
Acute kidney injury development after trauma, burn, or sepsis occurs frequently but remains a scientific and clinical challenge. Whereas the pathophysiological focus has mainly been on hemodynamics and the downstream renal tubular system, little is known about alterations upstream within the glomerulus post trauma or during sepsis. Particularly for the glomerular endothelial cells, mesangial cells, basal membrane, and podocytes, all of which form the glomerular filter, there are numerous in vitro studies on the molecular and functional consequences upon exposure of single cell types to specific damage- or microbial-associated molecular patterns. By contrast, a lack of knowledge exists in the real world regarding the orchestrated inflammatory response of the glomerulus post trauma or burn or during sepsis. Therefore, we aim to provide an overview on the glomerulus as an immune target but also as a perpetrator of the danger response to traumatic and septic conditions, and present major players involved in the context of critical illness. Finally, we highlight research gaps of this rather neglected but worthwhile area to define future molecular targets and therapeutic strategies to prevent or improve the course of AKI after trauma, burn, or sepsis.
Asunto(s)
Lesión Renal Aguda , Quemaduras , Sepsis , Humanos , Células Endoteliales , Glomérulos Renales , Quemaduras/complicaciones , Lesión Renal Aguda/etiología , Lesión Renal Aguda/terapia , Sepsis/complicacionesRESUMEN
Trauma is the leading cause of death in individuals under 44 years of age. Thorax trauma (TxT) is strongly associated with trauma-related death, an unbalanced innate immune response, sepsis, acute respiratory distress syndrome, and multiple organ dysfunction. It is shown that different in vivo traumata, such as TxT or an in vitro polytrauma cytokine cocktail trigger secretion of small extracellular nanovesicles (sEVs) from endothelial cells with pro-inflammatory cargo. These sEVs transfer transcripts for ICAM-1, VCAM-1, E-selectin, and cytokines to systemically activate the endothelium, facilitate neutrophil-endothelium interactions, and destabilize barrier integrity. Inhibition of sEV-release after TxT in mice ameliorates local as well as systemic inflammation, neutrophil infiltration, and distant organ damage in kidneys (acute kidney injury, AKI). Vice versa, injection of TxT-plasma-sEVs into healthy animals is sufficient to trigger pulmonary and systemic inflammation as well as AKI. Accordingly, increased sEV concentrations and transfer of similar cargos are observed in polytrauma patients, suggesting a fundamental pathophysiological mechanism.
Asunto(s)
Células Endoteliales/inmunología , Vesículas Extracelulares/inmunología , Inflamación/inmunología , Inflamación/fisiopatología , Traumatismo Múltiple/complicaciones , Lesión Renal Aguda/etiología , Lesión Renal Aguda/inmunología , Lesión Renal Aguda/fisiopatología , Animales , Modelos Animales de Enfermedad , Células Endoteliales/fisiología , Vesículas Extracelulares/fisiología , Masculino , Ratones , Ratones Endogámicos C57BL , Traumatismo Múltiple/inmunología , Infiltración Neutrófila/fisiología , Síndrome de Dificultad Respiratoria/etiología , Síndrome de Dificultad Respiratoria/inmunología , Síndrome de Dificultad Respiratoria/fisiopatología , Sepsis/etiología , Sepsis/inmunología , Sepsis/fisiopatologíaRESUMEN
Phagocytosis and the formation of reactive oxygen species (ROS) in phagocytic leukocytes are an effective killing mechanism of the innate host defense. These cellular processes of innate immunity function in a complex interplay with humoral factors. C-reactive protein (CRP) in its activated, monomeric isoform (mCRP) has been shown to activate immune cells via the classical complement pathway. We investigated the complement-dependent effects of monomeric CRP (mCRP) on neutrophils and monocyte subtypes using complement-specific inhibitors by both flow cytometry and confocal fluorescence microscopy. We demonstrate that CRP-induced ROS generation is a conformation-specific and complement-dependent process in leukocyte subsets with classical monocytes as the primary source of ROS amongst human monocyte subsets. Elucidation of this complex interplay of CRP and complement in inflammation pathophysiology might help to improve anti-inflammatory therapeutic strategies.
Asunto(s)
Proteína C-Reactiva/metabolismo , Activación de Complemento/inmunología , Proteínas del Sistema Complemento/inmunología , Citotoxicidad Inmunológica , Inmunidad Innata , Fagocitosis/inmunología , Especies Reactivas de Oxígeno/metabolismo , Interacciones Huésped-Patógeno/inmunología , Humanos , Leucocitos/inmunología , Leucocitos/metabolismo , Monocitos/inmunología , Monocitos/metabolismo , Neutrófilos/inmunología , Neutrófilos/metabolismoRESUMEN
Initially underestimated as platelet dust, extracellular vesicles are continuously gaining interest in the field of inflammation. Various studies addressing inflammatory diseases have shown that microvesicles (MVs) originating from different cell types are systemic transport vehicles carrying distinct cargoes to modulate immune responses. In this study, we focused on the clinical setting of multiple trauma, which is characterized by activation and dysfunction of both, the fluid-phase and the cellular component of innate immunity. Given the sensitivity of neutrophils for the complement anaphylatoxin C5a, we hypothesized that increased C5a production induces alterations in MV shedding of neutrophils resulting in neutrophil dysfunction that fuels posttraumatic inflammation. In a mono-centered prospective clinical study with polytraumatized patients, we found significantly increased granulocyte-derived MVs containing the C5a receptor (C5aR1, CD88) on their surface. This finding was accompanied by a concomitant loss of C5aR1 on granulocytes indicative of an impaired cellular chemotactic and pro-inflammatory neutrophil functions. Furthermore, in vitro exposure of human neutrophils (from healthy volunteers) to C5a significantly increased MV shedding and C5aR1 loss on neutrophils, which could be blocked using the C5aR1 antagonist PMX53. Mechanistic analyses revealed that the interaction between C5aR1 signaling and the small GTPase Arf6 acts as a molecular switch for MV shedding. When neutrophil derived, C5a-induced MV were exposed to a complex ex vivo whole blood model significant pro-inflammatory properties (NADPH activity, ROS and MPO generation) of the MVs became evident. C5a-induced MVs activated resting neutrophils and significantly induced IL-6 secretion. These data suggest a novel role of the C5a-C5aR1 axis: C5a-induced MV shedding from neutrophils results in decreased C5aR1 surface expression on the one hand, on the other hand it leads to profound inflammatory signals which likely are both key drivers of the neutrophil dysfunction which is regularly observed in patients suffering from multiple traumatic injuries.
Asunto(s)
Micropartículas Derivadas de Células/inmunología , Complemento C5a/metabolismo , Inmunidad Innata , Mediadores de Inflamación/metabolismo , Traumatismo Múltiple/inmunología , Neutrófilos/inmunología , Factor 6 de Ribosilación del ADP , Factores de Ribosilacion-ADP/metabolismo , Adulto , Estudios de Casos y Controles , Micropartículas Derivadas de Células/metabolismo , Femenino , Humanos , Puntaje de Gravedad del Traumatismo , Interleucina-6/metabolismo , Cinética , Masculino , Persona de Mediana Edad , Traumatismo Múltiple/sangre , Traumatismo Múltiple/diagnóstico , NADP/metabolismo , Neutrófilos/metabolismo , Peroxidasa/metabolismo , Estudios Prospectivos , Especies Reactivas de Oxígeno/metabolismo , Receptor de Anafilatoxina C5a/metabolismo , Transducción de Señal , Adulto JovenRESUMEN
Trauma represents a major socioeconomic burden worldwide. After a severe injury, hemorrhagic shock (HS) as a frequent concomitant aspect is a central driver of systemic inflammation and organ damage. The kidney is often strongly affected by traumatic-HS, and acute kidney injury (AKI) poses the patient at great risk for adverse outcome. Recently, thirty-eight-negative kinase 1 (TNK1) was proposed to play a detrimental role in organ damage after trauma/HS. Therefore, we aimed to assess the role of TNK1 in HS-induced kidney injury in a murine and a post hoc analysis of a non-human primate model of HS comparable to the clinical situation. Mice and non-human primates underwent resuscitated HS at 30 mmHg for 60 min. 5 h after the induction of shock, animals were assessed for systemic inflammation and TNK1 expression in the kidney. In vitro, murine distal convoluted tubule cells were stimulated with inflammatory mediators to gain mechanistic insights into the role of TNK1 in kidney dysfunction. In a translational approach, we investigated blood drawn from either healthy volunteers or severely injured patients at different time points after trauma (from arrival at the emergency room and at fixed time intervals until 10 days post injury; identifier: NCT02682550, https://clinicaltrials.gov/ct2/show/NCT02682550). A pronounced inflammatory response, as seen by increased IL-6 plasma levels as well as early signs of AKI, were observed in mice, non-human primates, and humans after trauma/HS. TNK1 was found in the plasma early after trauma-HS in trauma patients. Renal TNK1 expression was significantly increased in mice and non-human primates after HS, and these effects with concomitant induction of apoptosis were blocked by therapeutic inhibition of complement C3 activation in non-human primates. Mechanistically, in vitro data suggested that IL-6 rather than C3 cleavage products induced upregulation of TNK1 and impaired barrier function in renal epithelial cells. In conclusion, these data indicate that C3 inhibition in vivo may inhibit an excessive inflammatory response and mediator release, thereby indirectly neutralizing TNK1 as a potent driver of organ damage. In future studies, we will address the therapeutic potential of direct TNK1 inhibition in the context of severe tissue trauma with different degrees of additional HS.
Asunto(s)
Proteínas Fetales/metabolismo , Proteínas Tirosina Quinasas/metabolismo , Choque Hemorrágico/metabolismo , Heridas y Lesiones/metabolismo , Lesión Renal Aguda , Animales , Células Cultivadas , Complemento C3/metabolismo , Proteínas Fetales/genética , Voluntarios Sanos , Humanos , Mediadores de Inflamación/metabolismo , Interleucina-6/metabolismo , Riñón , Masculino , Ratones , Ratones Endogámicos C57BL , Modelos Animales , Primates , Proteínas Tirosina Quinasas/genéticaRESUMEN
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
RESUMEN
Clathrin-mediated endocytosis (CME) is critical for internalisation of molecules across cell membranes. The FCH domain only 1 (FCHO1) protein is key molecule involved in the early stages of CME formation. The consequences of mutations in FCHO1 in humans were unknown. We identify ten unrelated patients with variable T and B cell lymphopenia, who are homozygous for six distinct mutations in FCHO1. We demonstrate that these mutations either lead to mislocalisation of the protein or prevent its interaction with binding partners. Live-cell imaging of cells expressing mutant variants of FCHO1 provide evidence of impaired formation of clathrin coated pits (CCP). Patient T cells are unresponsive to T cell receptor (TCR) triggering. Internalisation of the TCR receptor is severely perturbed in FCHO1-deficient Jurkat T cells but can be rescued by expression of wild-type FCHO1. Thus, we discovered a previously unrecognised critical role of FCHO1 and CME during T-cell development and function in humans.
Asunto(s)
Endocitosis/fisiología , Mutación con Pérdida de Función , Linfopenia/genética , Proteínas de la Membrana/deficiencia , Linfocitos T/fisiología , Animales , Linfocitos T CD4-Positivos/patología , Diferenciación Celular , Células Cultivadas , Femenino , Infecciones por VIH/genética , VIH-1/patogenicidad , Humanos , Células Jurkat , Linfopenia/patología , Masculino , Proteínas de la Membrana/química , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Ratones , Linaje , Receptores de Antígenos de Linfocitos T/metabolismo , Linfocitos T/virologíaRESUMEN
[This corrects the article DOI: 10.3389/fimmu.2019.00543.].
RESUMEN
Exposure to traumatic or infectious insults results in a rapid activation of the complement cascade as major fluid defense system of innate immunity. The complement system acts as a master alarm system during the molecular danger response after trauma and significantly contributes to the clearance of DAMPs and PAMPs. However, depending on the origin and extent of the damaged macro- and micro -milieu, the complement system can also be either excessively activated or inhibited. In both cases, this can lead to a maladaptive immune response and subsequent multiple cellular and organ dysfunction. The arsenal of complement-specific drugs offers promising strategies for various critical conditions after trauma, hemorrhagic shock, sepsis, and multiple organ failure. The imbalanced immune response needs to be detected in a rational and real-time manner before the translational therapeutic potential of these drugs can be fully utilized. Overall, the temporal-spatial complement response after tissue trauma and during sepsis remains somewhat enigmatic and demands a clinical triad: reliable tissue damage assessment, complement activation monitoring, and potent complement targeting to highly specific rebalance the fluid phase innate immune response.
Asunto(s)
Proteínas del Sistema Complemento/inmunología , Insuficiencia Multiorgánica/inmunología , Traumatismo Múltiple/inmunología , Sepsis/inmunología , Animales , Humanos , Insuficiencia Multiorgánica/etiología , Traumatismo Múltiple/complicaciones , Sepsis/complicaciones , Choque Hemorrágico/complicaciones , Choque Hemorrágico/inmunologíaRESUMEN
The overpowering effect of trauma on the immune system is undisputed. Severe trauma is characterized by systemic cytokine generation, activation and dysregulation of systemic inflammatory response complementopathy and coagulopathy, has been immensely instrumental in understanding the underlying mechanisms of the innate immune system during systemic inflammation. The compartmentalized functions of the innate and adaptive immune systems are being gradually recognized as an overlapping, interactive and dynamic system of responsive elements. Nonetheless the current knowledge of the complement cascade and its interaction with adaptive immune response mediators and cells, including T- and B-cells, is limited. In this review, we discuss what is known about the bridging effects of the complement system on the adaptive immune system and which unexplored areas could be crucial in understanding how the complement and adaptive immune systems interact following trauma.
Asunto(s)
Linfocitos B/inmunología , Proteínas del Sistema Complemento/metabolismo , Linfocitos T/inmunología , Heridas y Lesiones/inmunología , Inmunidad Adaptativa , Animales , Activación de Complemento , Citocinas/metabolismo , Humanos , Inmunidad InnataRESUMEN
Inhibitors of Wnt production (IWPs) are known antagonists of the Wnt pathway, targeting the membrane-bound O-acyltransferase porcupine (Porcn) and thus preventing a crucial Wnt ligand palmitoylation. Since IWPs show structural similarities to benzimidazole-based CK1 inhibitors, we hypothesized that IWPs could also inhibit CK1 isoforms. Molecular modeling revealed a plausible binding mode of IWP-2 in the ATP binding pocket of CK1δ which was confirmed by X-ray analysis. In vitro kinase assays demonstrated IWPs to be ATP-competitive inhibitors of wtCK1δ. IWPs also strongly inhibited the gatekeeper mutant M82FCK1δ. When profiled in a panel of 320 kinases, IWP-2 specifically inhibited CK1δ. IWP-2 and IWP-4 also inhibited the viability of various cancer cell lines. By a medicinal chemistry approach, we developed improved IWP-derived CK1 inhibitors. Our results suggest that the effects of IWPs are not limited to Porcn, but also might influence CK1δ/ε-related pathways.
Asunto(s)
Adenosina Trifosfato/metabolismo , Caseína Cinasa 1 épsilon/antagonistas & inhibidores , Quinasa Idelta de la Caseína/antagonistas & inhibidores , Diseño de Fármacos , Inhibidores de Proteínas Quinasas/química , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Wnt/biosíntesis , Bencimidazoles/química , Bencimidazoles/metabolismo , Bencimidazoles/farmacología , Unión Competitiva , Caseína Cinasa 1 épsilon/química , Caseína Cinasa 1 épsilon/metabolismo , Quinasa Idelta de la Caseína/química , Quinasa Idelta de la Caseína/metabolismo , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Humanos , Modelos Moleculares , Conformación Proteica , Inhibidores de Proteínas Quinasas/metabolismoRESUMEN
Cells communicate with other cells in their microenvironment by transferring lipids, peptides, RNA, and sugars in extracellular vesicles (EVs), thereby also influencing recipient cell functions. Several studies indicate that these vesicles are involved in a variety of critical cellular processes including immune, metabolic, and coagulatory responses and are thereby associated with several inflammatory diseases. Furthermore, EVs also possess anti-inflammatory properties and contribute to immune regulation, thus encouraging an emerging interest in investigating and clarifying mechanistic links between EVs and innate immunity. Current studies indicate complex interactions of the complement system with EVs, with a dramatic influence on local and systemic inflammation. During inflammatory conditions with highly activated complement, including after severe tissue trauma and during sepsis, elevated numbers of EVs were found in the circulation of patients. There is increasing evidence that these shed vesicles contain key complement factors as well as complement regulators on their surface, affecting inflammation and the course of disease. Taken together, interaction of EVs regulates complement activity and contributes to the pro- and anti-inflammatory immune balance. However, the molecular mechanisms behind this interaction remain elusive and require further investigation. The aim of this review is to summarize the limited current knowledge on the crosstalk between complement and EVs. A further aspect is the clinical relevance of EVs with an emphasis on their capacity as potential therapeutic vehicles in the field of translational medicine.
Asunto(s)
Proteínas del Sistema Complemento/inmunología , Proteínas del Sistema Complemento/metabolismo , Vesículas Extracelulares/inmunología , Vesículas Extracelulares/metabolismo , Animales , Biomarcadores , Coagulación Sanguínea , Activación de Complemento/inmunología , Susceptibilidad a Enfermedades , Sistemas de Liberación de Medicamentos , Espacio Extracelular/inmunología , Espacio Extracelular/metabolismo , Humanos , Inmunidad Innata , InmunomodulaciónRESUMEN
Traumatic brain injury (TBI) and spinal cord injury (SCI) are critical medical conditions and a public health problem for which limited therapeutic options are available. The complement cascade is activated after TBI and SCI, and the resulting effects have been investigated in gene-knockout and pharmacological models. Multiple experimental studies support a net detrimental role of C3 and C5 activation in the early stages of TBI and SCI. Less firm experimental evidence suggests that, downstream of C3/C5, effector mechanisms, including the generation of membrane-activated complex and direct damage to membranes and neutrophils infiltration, may bring about the direct damage of central nervous system tissue and enhancement of neuroinflammation. The role of upstream classical, alternative, or extrinsic complement activation cascades remains unclear. Although several issues remain to be investigated, current evidence supports the investigation of a number of complement-targeting agents targeting C3 or C5, such as eculizumab, for repurposing in TBI and SCI treatment.
Asunto(s)
Lesiones Traumáticas del Encéfalo/inmunología , Lesiones Traumáticas del Encéfalo/patología , Activación de Complemento , Traumatismos de la Médula Espinal/inmunología , Traumatismos de la Médula Espinal/patología , Animales , HumanosRESUMEN
BACKGROUND: Beta-thalassemia major (ß-TM) patients need blood transfusions, which result in iron deposition. To regulate chelation therapy, iron load has to be measured. With MRI, the amount of signal loss and T2* decay time shortening are used for iron quantification. OBJECTIVES: The aim was to measure adrenal iron load with T2* relaxometry using MRI, and to compare it with liver and cardiac iron and serum ferritin, and to find out whether adrenal iron could be predicted from those parameters. PATIENTS AND METHODS: Between October 2014 and March 2015, MRI was performed in 21 patients with ß-TM, recieving blood transfusions and chelation therapy. The control group (n = 11) included healthy volunteers with no known history of adrenal, hematologic, chronic disease, and blood transfusion. RESULTS: Among patients, there was no significant correlation between plasma ferritin and adrenal T2*. Significant difference was detected among T2* values of adrenals between the patient and control groups. There was no significant correlation between adrenal gland and liver T2* in ß-TM patients, moderate correlation was detected between adrenal T2* and cardiac T2*. CONCLUSION: Adrenal iron in ß-TM can be reliably measured in 3 Tesla MRI. The results highlight the absence of correlation between adrenal iron deposition both with serum ferritin and hepatic iron.