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Lung transplant recipients (LTR) are susceptible to severe COVID-19 and had lower immune responses to primary SARS-CoV-2 vaccination as compared to the general population and to other solid organ transplant recipients. As immunity induced by booster vaccination and natural infection has increased since the beginning of the pandemic in the general population, immunity acquired by LTR is not well documented. Humoral and cellular immunity to SARS-CoV-2 was monitored in February and May 2023 in 30 LTR and compared to that of health care workers (HCW) and nursing home residents (NHR). LTR had significantly lower levels of SARS-CoV-2 binding and neutralizing antibodies and lower IFN-γ responses to Wuhan, Delta and XBB1.5 variants as compared to HCW and NHR. Humoral immunity decreased between the two visits whereas cellular immunity remained more stable. The persistent defect in SARS-CoV-2 immunity in LTR should encourage continued monitoring and preventive measures for this vulnerable population.
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BACKGROUND: Conventional natural killer (cNK) cells play an important role in the innate immune response by directly killing infected and malignant cells and by producing pro- and anti-inflammatory cytokines. Studies on their role in malaria and its complications have resulted in conflicting results. METHODS: Using the commonly used anti-NK1.1 depletion antibodies (PK136) in an in-house optimized experimental model for malaria-associated acute respiratory distress syndrome (MA-ARDS), the role of cNK cells was investigated. Moreover, flow cytometry was performed to characterize different NK cell populations. RESULTS: While cNK cells were found to be dispensable in the development of MA-ARDS, the appearance of a NK1.1+ cell population was observed in the lungs upon infection despite depletion with anti-NK1.1. Detailed characterization of the unknown population revealed that this population consisted of a mixture of monocytes and macrophages that bind the anti-NK1.1 antibody in an aspecific way. This aspecific binding may occur via Fcγ receptors, such as FcγR4. In contrast, in vivo depletion using anti-NK1.1 antibodies was proved to be specific for cNK cells. CONCLUSION: cNK cells are dispensable in the development of experimental MA-ARDS. Moreover, careful flow cytometric analysis, with a critical mindset in relation to potential aspecific binding despite the use of commercially available Fc blocking reagents, is critical to avoid misinterpretation of the results.
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Malária , Síndrome do Desconforto Respiratório , Camundongos , Animais , Camundongos Endogâmicos C57BL , Síndrome do Desconforto Respiratório/patologia , Células Matadoras Naturais , Células Mieloides/patologia , Malária/complicaçõesRESUMO
Plasmodium parasites cause malaria, a global health disease that is responsible for more than 200 million clinical cases and 600 000 deaths each year. Most deaths are caused by various complications, including malaria-associated acute respiratory distress syndrome (MA-ARDS). Despite the very rapid and efficient killing of parasites with antimalarial drugs, 15% of patients with complicated malaria succumb. This stresses the importance of investigating resolution mechanisms that are involved in the recovery from these complications once the parasite is killed. To study the resolution of MA-ARDS, P. berghei NK65-infected C57BL/6 mice were treated with antimalarial drugs after onset of symptoms, resulting in 80% survival. Micro-computed tomography revealed alterations of the lungs upon infection, with an increase in total and non-aerated lung volume due to edema. Whole body plethysmography confirmed a drastically altered lung ventilation, which was restored during resolution. Single-cell RNA sequencing indicated an increased inflammatory state in the lungs upon infection, which was accompanied by a drastic decrease in endothelial cells, consistent with CD8+ T cell-mediated killing. During resolution, anti-inflammatory pathways were upregulated and proliferation of endothelial cells was observed. MultiNicheNet interactome analysis identified important changes in the ligand-receptor interactions during disease resolution that warrant further exploration in order to develop new therapeutic strategies. In conclusion, our study provides insights in pro-resolving pathways that limit inflammation and promote endothelial cell proliferation in experimental MA-ARDS. This information may be useful for the design of adjunctive treatments to enhance resolution after Plasmodium parasite killing by antimalarial drugs.
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Antimaláricos , Malária , Síndrome do Desconforto Respiratório , Humanos , Animais , Camundongos , Antimaláricos/farmacologia , Antimaláricos/uso terapêutico , Células Endoteliais/metabolismo , Microtomografia por Raio-X/efeitos adversos , Camundongos Endogâmicos C57BL , Síndrome do Desconforto Respiratório/etiologia , Síndrome do Desconforto Respiratório/metabolismo , Malária/parasitologia , Análise de Sequência de RNA , Plasmodium bergheiRESUMO
Introduction: Malaria remains a widespread health problem with a huge burden. Severe or complicated malaria is highly lethal and encompasses a variety of pathological processes, including immune activation, inflammation, and dysmetabolism. Previously, we showed that adrenal hormones, in particular glucocorticoids (GCs), play critical roles to maintain disease tolerance during Plasmodium infection in mice. Here, GC responses were studied in Cameroon in children with uncomplicated malaria (UM), severe malaria (SM) and asymptomatic controls (AC). Methods: To determine the sensitivity of leukocytes to GC signaling on a transcriptional level, we measured the ex vivo induction of glucocorticoid induced leucine zipper (GILZ) and FK506-binding protein 5 (FKBP5) by GCs in human and murine leukocytes. Targeted tracer metabolomics on peripheral blood mononuclear cells (PBMCs) was performed to detect metabolic changes induced by GCs. Results: Total cortisol levels increased in patients with clinical malaria compared to AC and were higher in the SM versus UM group, while cortisol binding globulin levels were unchanged and adrenocorticotropic hormone (ACTH) levels were heterogeneous. Induction of both GILZ and FKBP5 by GCs was significantly reduced in patients with clinical malaria compared to AC and in malaria-infected mice compared to uninfected controls. Increased activity in the pentose phosphate pathway was found in the patients, but this was not affected by ex vivo stimulation with physiological levels of hydrocortisone. Interestingly, hydrocortisone induced increased levels of cAMP in AC, but not in clinical malaria patients. Discussion: Altogether, this study shows that patients with SM have increased cortisol levels, but also a decreased sensitivity to GCs, which may clearly contribute to the severity of disease.
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Glucocorticoides , Malária , Humanos , Criança , Camundongos , Animais , Glucocorticoides/farmacologia , Glucocorticoides/metabolismo , Hidrocortisona , Leucócitos Mononucleares/metabolismo , Receptores de Glucocorticoides/metabolismo , Fatores de Transcrição/metabolismoRESUMO
[This corrects the article DOI: 10.3389/fimmu.2020.628643.].
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Malaria is a hazardous disease caused by Plasmodium parasites and often results in lethal complications, including malaria-associated acute respiratory distress syndrome (MA-ARDS). Parasite sequestration in the microvasculature is often observed, but its role in malaria pathogenesis and complications is still incompletely understood. We used skeleton binding protein-1 (SBP-1) KO parasites to study the role of sequestration in experimental MA-ARDS. The sequestration-deficiency of these SBP-1 KO parasites was confirmed with bioluminescence imaging and by measuring parasite accumulation in the lungs with RT-qPCR. The SBP-1 KO parasites induced similar lung pathology in the early stage of experimental MA-ARDS compared to wildtype (WT) parasites. Strikingly, the lung pathology resolved subsequently in more than 60% of the SBP-1 KO infected mice, resulting in prolonged survival despite the continuous presence of the parasite. This spontaneous disease resolution was associated with decreased inflammatory cytokine expression measured by RT-qPCR and lower expression of cytotoxic markers in pathogenic CD8+ T cells in the lungs of SBP-1 KO infected mice. These data suggest that SBP-1-mediated parasite sequestration and subsequent high parasite load are not essential for the development of experimental MA-ARDS but inhibit the resolution of the disease.
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Pulmão/parasitologia , Malária/complicações , Proteínas de Membrana/deficiência , Plasmodium berghei/patogenicidade , Proteínas de Protozoários/metabolismo , Síndrome do Desconforto Respiratório/prevenção & controle , Animais , Progressão da Doença , Feminino , Pulmão/metabolismo , Pulmão/patologia , Malária/parasitologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Proteínas de Protozoários/genética , Síndrome do Desconforto Respiratório/metabolismo , Síndrome do Desconforto Respiratório/parasitologia , Síndrome do Desconforto Respiratório/patologiaRESUMO
Lactic acidosis and hyperlactatemia are common metabolic disturbances in patients with severe malaria. Lactic acidosis causes physiological adverse effects, which can aggravate the outcome of malaria. Despite its clear association with mortality in malaria patients, the etiology of lactic acidosis is not completely understood. In this review, the possible contributors to lactic acidosis and hyperlactatemia in patients with malaria are discussed. Both increased lactate production and impaired lactate clearance may play a role in the pathogenesis of lactic acidosis. The increased lactate production is caused by several factors, including the metabolism of intraerythrocytic Plasmodium parasites, aerobic glycolysis by activated immune cells, and an increase in anaerobic glycolysis in hypoxic cells and tissues as a consequence of parasite sequestration and anemia. Impaired hepatic and renal lactate clearance, caused by underlying liver and kidney disease, might further aggravate hyperlactatemia. Multiple factors thus participate in the etiology of lactic acidosis in malaria, and further investigations are required to fully understand their relative contributions and the consequences of this major metabolic disturbance.
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Acidose Láctica/etiologia , Malária/complicações , Plasmodium/fisiologia , Acidose Láctica/patologia , HumanosRESUMO
Malaria complications are often lethal, despite efficient killing of Plasmodium parasites with antimalarial drugs. This indicates the need to study the resolution and healing mechanisms involved in the recovery from these complications. Plasmodium berghei NK65-infected C57BL/6 mice develop malaria-associated acute respiratory distress syndrome (MA-ARDS) at 8 days post infection. Antimalarial treatment was started on this day and resulted in the recovery, as measured by the disappearance of the signs of pathology, in >80% of the mice. Therefore, this optimized model represents an asset in the study of mechanisms and leukocyte populations involved in the resolution of MA-ARDS. C-C chemokine receptor type 2 (CCR2) knock-out mice were used to investigate the role of monocytes and macrophages, since these cells are described to play an important role during the resolution of other inflammatory diseases. CCR2 deficiency was associated with significantly lower numbers of inflammatory monocytes in the lungs during infection and resolution and abolished the increase in non-classical monocytes during resolution. Surprisingly, CCR2 was dispensable for the development and the resolution of MA-ARDS, since no effect of the CCR2 knock-out was observed on any of the disease parameters. In contrast, the reappearance of eosinophils and interstitial macrophages during resolution was mitigated in the lungs of CCR2 knock-out mice. In conclusion, CCR2 is required for re-establishing the homeostasis of pulmonary leukocytes during recovery. Furthermore, the resolution of malaria-induced lung pathology is mediated by unknown CCR2-independent mechanisms.
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Homeostase/imunologia , Leucócitos/imunologia , Malária/imunologia , Plasmodium berghei/imunologia , Receptores CCR2/imunologia , Síndrome do Desconforto Respiratório/imunologia , Animais , Homeostase/genética , Leucócitos/patologia , Malária/genética , Malária/patologia , Camundongos , Camundongos Knockout , Receptores CCR2/genética , Síndrome do Desconforto Respiratório/genética , Síndrome do Desconforto Respiratório/parasitologia , Síndrome do Desconforto Respiratório/patologiaRESUMO
During malaria, the hypothalamic-pituitary-adrenal (HPA) axis is activated and glucocorticoid (GC) levels are increased, but their essential roles have been largely overlooked. GCs are decisive for systemic regulation of vital processes such as immune responses, vascular function, and metabolism, which are crucial in malaria. Here, we introduce GCs in general, followed by their versatile roles for disease tolerance in malaria. A complementary comparison is provided with their role in sepsis. Finally, potential translational implications are considered. The failed clinical trials of dexamethasone against cerebral malaria in the past have diminished the interest in GCs in malaria. However, the issue of relative corticosteroid insufficiency has barely been explored in malaria patients, but may hold promise for a better understanding and treatment of specific malaria complications.
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Resistência à Doença/imunologia , Glucocorticoides/imunologia , Malária/imunologia , Corticosteroides/deficiência , Humanos , Sistema Hipotálamo-Hipofisário/imunologia , Malária/fisiopatologiaRESUMO
Neutrophil-depleting antibodies, such as anti-GR1 (RB6-8C5) and anti-Ly6G (1A8), are commonly used to study the in vivo function of neutrophils in murine disease models. Anti-Ly6G antibodies became the standard, because in contrast to anti-GR1, these do not bind Ly6C. The efficiency of the depletion needs to be carefully analysed as flow cytometry plots may be misinterpreted. For example, the staining intensity of GR1 on neutrophils (CD11b+ GR1hi) drops upon anti-Ly6G administration. We show that this drop is due to competition between anti-GR1 and anti-Ly6G antibodies. Neutrophil depletion with anti-Ly6G in naive mice was organ- and strain-specific. Furthermore, an incomplete anti-Ly6G-dependent neutrophil depletion was obtained in two immune-mediated mouse models, i.e. in malaria-infected C57BL/6 mice and in complete Freund's adjuvant (CFA)-challenged BALB/c mice. BrdU-incorporation studies show a slight increase in proliferating bone marrow neutrophils upon depletion in naive mice. Strikingly, depletion with anti-Ly6G in CFA-challenged BALB/c mice resulted in a significant increase in proliferating splenic neutrophils, causing a fast rebound of new immature neutrophils. In conclusion, our results emphasize the importance of careful panel design, gating strategies and duration of neutrophil depletion and highlight the context-dependent Ly6G depletion efficiency. It furthermore underlines the need for new tools to understand the in vivo role of neutrophils in immunological models.
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Anticorpos Monoclonais/administração & dosagem , Antígenos Ly/imunologia , Tolerância Imunológica/efeitos dos fármacos , Inflamação/imunologia , Neutrófilos/efeitos dos fármacos , Animais , Anticorpos Monoclonais/imunologia , Proliferação de Células/efeitos dos fármacos , Modelos Animais de Doenças , Humanos , Inflamação/induzido quimicamente , Injeções Intraperitoneais , Camundongos , Camundongos Endogâmicos C57BL , Neutrófilos/imunologia , Baço/citologia , Baço/imunologiaRESUMO
Malaria reduces host fitness and survival by pathogen-mediated damage and inflammation. Disease tolerance mechanisms counter these negative effects without decreasing pathogen load. Here, we demonstrate that in four different mouse models of malaria, adrenal hormones confer disease tolerance and protect against early death, independently of parasitemia. Surprisingly, adrenalectomy differentially affects malaria-induced inflammation by increasing circulating cytokines and inflammation in the brain but not in the liver or lung. Furthermore, without affecting the transcription of hepatic gluconeogenic enzymes, adrenalectomy causes exhaustion of hepatic glycogen and insulin-independent lethal hypoglycemia upon infection. This hypoglycemia is not prevented by glucose administration or TNF-α neutralization. In contrast, treatment with a synthetic glucocorticoid (dexamethasone) prevents the hypoglycemia, lowers cerebral cytokine expression and increases survival rates. Overall, we conclude that in malaria, adrenal hormones do not protect against lung and liver inflammation. Instead, they prevent excessive systemic and brain inflammation and severe hypoglycemia, thereby contributing to tolerance.
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Glândulas Suprarrenais/metabolismo , Encéfalo/imunologia , Citocinas/imunologia , Hormônios/imunologia , Hipoglicemia/imunologia , Fígado/imunologia , Pulmão/imunologia , Malária/imunologia , Glândulas Suprarrenais/imunologia , Adrenalectomia , Animais , Glicemia/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Corticosterona/imunologia , Corticosterona/metabolismo , Citocinas/efeitos dos fármacos , Dexametasona/farmacologia , Modelos Animais de Doenças , Epinefrina/imunologia , Epinefrina/metabolismo , Glucocorticoides/imunologia , Glucocorticoides/farmacologia , Glicogênio/metabolismo , Hidrocortisona/imunologia , Hidrocortisona/metabolismo , Inflamação , Fígado/efeitos dos fármacos , Pulmão/efeitos dos fármacos , Camundongos , Mineralocorticoides/imunologia , Mineralocorticoides/metabolismo , Norepinefrina/imunologia , Norepinefrina/metabolismo , Plasmodium berghei , Plasmodium chabaudi , Taxa de SobrevidaRESUMO
BACKGROUND: Malaria-associated acute respiratory distress syndrome (MA-ARDS) is a complication of malaria with a lethality rate of up to 80% despite anti-malarial treatment. It is characterized by a vast infiltration of leukocytes, microhaemorrhages and vasogenic oedema in the lungs. Previously, a mouse model for MA-ARDS was developed by infection of C57BL/6 mice with the Edinburgh line NK65-E of Plasmodium berghei. RESULTS: Here, both host and parasite factors were demonstrated to play crucial roles in the development and severity of lung pathology. In particular, the genetic constitution of the host was an important determinant in the development of MA-ARDS. Both male and female C57BL/6, but not BALB/c, mice developed MA-ARDS when infected with P. berghei NK65-E. However, the New York line of P. berghei NK65 (NK65-NY) did not induce demonstrable MA-ARDS, despite its accumulation in the lungs and fat tissue to a similar or even higher extent as P. berghei NK65-E. These two commonly used lines of P. berghei differ in their red blood cell preference. P. berghei NK65-NY showed a stronger predilection for reticulocytes than P. berghei NK65-E and this appeared to be associated with a lower pathogenicity in the lungs. The pulmonary pathology in the C57BL/6/P. berghei NK65-E model was more pronounced than in the model with infection of DBA/2 mice with P. berghei strain ANKA. The transient lung pathology in DBA/2 mice infected with P. berghei ANKA coincided with the infection phase in which parasites mainly infected normocytes. This phase was followed by a less pathogenic phase in which P. berghei ANKA mainly infected reticulocytes. CONCLUSIONS: The propensity of mice to develop MA-ARDS during P. berghei infection depends on both host and parasite factors and appears to correlate with RBC preference. These data provide insights in induction of MA-ARDS and may guide the choice of different mouse-parasite combinations to study lung pathology.
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Modelos Animais de Doenças , Malária/complicações , Plasmodium berghei/patogenicidade , Síndrome do Desconforto Respiratório/patologia , Animais , Feminino , Interações Hospedeiro-Parasita , Pulmão/patologia , Malária/parasitologia , Masculino , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BLRESUMO
Malaria is a severe disease and kills over 400,000 people each year. Malarial complications are the main cause of death and include cerebral malaria and malaria-associated acute respiratory distress syndrome (MA-ARDS). Despite antimalarial treatment, lethality rates of MA-ARDS are still between 20 and 80%. Patients develop pulmonary edema with hemorrhages and leukocyte extravasation in the lungs. The vascular endothelial growth factor-A (VEGF-A) and the placental growth factor (PlGF) are vascular permeability factors and may be involved in the disruption of the alveolar-capillary membrane, leading to alveolar edema. We demonstrated increased pulmonary VEGF-A and PlGF levels in lungs of mice with experimental MA-ARDS. Depletion of pathogenic CD8+ T cells blocked pulmonary edema and abolished the increase of VEGF-A and PlGF. However, neutralization of VEGF receptor-2 (VEGFR-2) with the monoclonal antibody clone DC101 did not decrease pulmonary pathology. The broader spectrum receptor tyrosine kinase inhibitor sunitinib even increased lung pathology. These data suggest that the increase in alveolar VEGF-A and PlGF is not a cause but rather a consequence of the pulmonary pathology in experimental MA-ARDS and that therapeutic inhibition of VEGF receptors is not effective and even contra-indicated.
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Linfócitos T CD8-Positivos/imunologia , Malária/complicações , Síndrome do Desconforto Respiratório/etiologia , Fator A de Crescimento do Endotélio Vascular/metabolismo , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/metabolismo , Células Epiteliais Alveolares , Animais , Anticorpos Monoclonais/imunologia , Anticorpos Neutralizantes , Linfócitos T CD8-Positivos/fisiologia , Citocinas/metabolismo , Modelos Animais de Doenças , Edema/etiologia , Feminino , Regulação da Expressão Gênica , Imunoglobulina G/sangue , Imuno-Histoquímica , Pulmão/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fator de Crescimento Placentário/metabolismo , Plasmodium berghei , Síndrome do Desconforto Respiratório/tratamento farmacológico , Síndrome do Desconforto Respiratório/patologia , Fator A de Crescimento do Endotélio Vascular/genética , Receptor 1 de Fatores de Crescimento do Endotélio Vascular/efeitos dos fármacos , Receptor 1 de Fatores de Crescimento do Endotélio Vascular/imunologia , Receptor 1 de Fatores de Crescimento do Endotélio Vascular/metabolismo , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/efeitos dos fármacos , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/imunologiaRESUMO
Astemizole is a H1-antagonist endowed with antimalarial activity, but has hERG liabilities. Systematic structural modifications of astemizole led to the discovery of analogues that display very potent activity as inhibitors of the growth of the Plasmodium parasite, but show a decreased hERG inhibition, when compared to astemizole. These compounds can be used as starting point for the development of a new class of antimalarials.
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Antimaláricos/farmacologia , Astemizol/farmacologia , Plasmodium falciparum/efeitos dos fármacos , Antimaláricos/síntese química , Antimaláricos/química , Astemizol/síntese química , Astemizol/química , Relação Dose-Resposta a Droga , Humanos , Estrutura Molecular , Testes de Sensibilidade Parasitária , Plasmodium falciparum/crescimento & desenvolvimento , Relação Estrutura-Atividade , Regulador Transcricional ERG/antagonistas & inibidores , Regulador Transcricional ERG/metabolismoRESUMO
OBJECTIVE: Pouchitis is the most common complication after colectomy with ileal pouch-anal anastomosis (IPAA) for UC and the risk is the highest within the 1st year after surgery. The pathogenesis is not completely understood but clinical response to antibiotics suggests a role for gut microbiota. We hypothesised that the risk for pouchitis can be predicted based on the faecal microbial composition before colectomy. DESIGN: Faecal samples from 21 patients with UC undergoing IPAA were prospectively collected before colectomy and at predefined clinical visits at 1 month, 3 months, 6 months and 12â months after IPAA. The predominant microbiota was analysed using community profiling with denaturing gradient gel electrophoresis followed by quantitative real-time PCR validation. RESULTS: Cluster analysis before colectomy distinguished patients with pouchitis from those with normal pouch during the 1st year of follow-up. In patients developing pouchitis, an increase of Ruminococcus gnavus (p<0.001), Bacteroides vulgatus (p=0.043), Clostridium perfringens (p=0.011) and a reduction of two Lachnospiraceae genera (Blautia (p=0.04), Roseburia (p=0.008)) was observed. A score combining these five bacterial risk factors was calculated and presence of at least two risk factors showed a sensitivity and specificity of 100% and 63.6%, respectively. CONCLUSIONS: Presence of R. gnavus, B. vulgatus and C. perfringens and absence of Blautia and Roseburia in faecal samples of patients with UC before surgery is associated with a higher risk of pouchitis after IPAA. Our findings suggest new predictive and therapeutic strategies in patients undergoing colectomy with IPAA.