RESUMEN
Cladribine (Mavenclad®) is an oral treatment for relapsing remitting MS (RRMS), but its mechanism of action and its effects on innate immune responses in unknown. This study is a prospective Phase IV study of 41 patients with RRMS, and aims to investigate the mechanism of action of cladribine on peripheral monocytes, and its impact on the P2X7 receptor. There was a significant reduction in monocyte count in vivo at week 1 post cladribine administration, and the subset of cells being most impacted were the CD14lo CD16+ 'non-classical' monocytes. Of the 14 cytokines measured in serum, CCL2 levels increased at week 1. In vitro, cladrabine induced a reduction in P2X7R pore as well as channel activity. This study demonstrates a novel mechanism of action for cladribine. It calls for studying potential benefits of cladribine in progressive forms of MS and other neurodegenerative diseases where innate immune related inflammation is implicated in disease pathogenesis.
Asunto(s)
Cladribina , Citocinas , Inmunidad Innata , Monocitos , Esclerosis Múltiple Recurrente-Remitente , Humanos , Cladribina/uso terapéutico , Cladribina/farmacología , Inmunidad Innata/efectos de los fármacos , Femenino , Masculino , Adulto , Estudios Prospectivos , Esclerosis Múltiple Recurrente-Remitente/tratamiento farmacológico , Esclerosis Múltiple Recurrente-Remitente/inmunología , Esclerosis Múltiple Recurrente-Remitente/sangre , Monocitos/inmunología , Monocitos/efectos de los fármacos , Persona de Mediana Edad , Citocinas/sangre , Citocinas/inmunología , Receptores Purinérgicos P2X7/inmunología , Inmunosupresores/uso terapéutico , Inmunosupresores/farmacología , Adulto JovenRESUMEN
Glioblastoma is the most aggressive and lethal primary brain malignancy with limited treatment options and poor prognosis. Self-renewing glioblastoma cancer stem cells (GSCs) facilitate tumour progression, resistance to conventional treatment and tumour recurrence. GSCs are resistant to standard treatments. There is a need for novel treatment alternatives that effectively target GSCs. The purinergic P2X receptor 7 (P2X7R) is expressed in glioblastomas and has been implicated in disease pathogenesis. However, the roles of P2X7R have not been comprehensively elucidated in conventional treatment-resistant GSCs. This study characterised P2X7R channel and pore function and investigated the effect of pharmacological P2X7R inhibition in GSCs. Immunofluorescence and live cell fluorescent dye uptake experiments revealed P2X7R expression, and channel and pore function in GSCs. Treatment of GSCs with the P2X7R antagonist, AZ10606120 (AZ), for 72â¯hours significantly reduced GSC numbers, compared to untreated cells. When compared with the effect of the first-line conventional chemotherapy, temozolomide (TMZ), GSCs treated with AZ had significantly lower cell numbers than TMZ-treated cultures, while TMZ treatment alone did not significantly deplete GSC numbers compared to the control. AZ treatment also induced significant lactate dehydrogenase release by GSCs, indicative of treatment-induced cytotoxic cell death. There were no significant differences in the expression of apoptotic markers, Annexin V and cleaved caspase-3, between AZ-treated cells and the control. Collectively, this study reveals for the first time functional P2X7R channel and pore in GSCs and significant GSC depletion following P2X7R inhibition by AZ. These results indicate that P2X7R inhibition may be a novel therapeutic alternative for glioblastoma, with effectiveness against GSCs resistant to conventional chemotherapy.
Asunto(s)
Neoplasias Encefálicas , Glioblastoma , Células Madre Neoplásicas , Antagonistas del Receptor Purinérgico P2X , Receptores Purinérgicos P2X7 , Temozolomida , Glioblastoma/metabolismo , Glioblastoma/tratamiento farmacológico , Glioblastoma/patología , Células Madre Neoplásicas/efectos de los fármacos , Células Madre Neoplásicas/metabolismo , Humanos , Receptores Purinérgicos P2X7/metabolismo , Antagonistas del Receptor Purinérgico P2X/farmacología , Temozolomida/farmacología , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/tratamiento farmacológico , Neoplasias Encefálicas/patología , Línea Celular Tumoral , Piridinas/farmacología , Apoptosis/efectos de los fármacos , Adamantano/análogos & derivados , AminoquinolinasRESUMEN
The intestinal microbiota regulates immunity across organ systems. Which symbionts control systemic immunity, the mechanisms they use, and how they avoid widespread inflammatory damage are unclear. We uncover host tolerance and resistance mechanisms that allow Firmicutes from the human microbiota to control systemic immunity without inducing immunopathology. Intestinal processing releases Firmicute glycoconjugates that disseminate, resulting in release of cytokine IL-34 that stimulates macrophages and enhances defenses against pneumonia, sepsis, and meningitis. Despite systemic penetration of Firmicutes, immune homeostasis is maintained through feedback control whereby IL-34-mediated mTORC1 activation in macrophages clears polymeric glycoconjugates from peripheral tissues. Smaller glycoconjugates evading this clearance mechanism are tolerated through sequestration by albumin, which acts as an inflammatory buffer constraining their immunological impact. Without these resistance and tolerance mechanisms, Firmicutes drive catastrophic organ damage and cachexia via IL-1ß. This reveals how Firmicutes are safely assimilated into systemic immunity to protect against infection without threatening host viability.
Asunto(s)
Firmicutes , Microbiota , Humanos , Simbiosis , Tolerancia Inmunológica , Citocinas , Interleucinas , Inmunidad InnataRESUMEN
Glioblastomas are highly aggressive and deadly brain tumours, with a median survival time of 14-18 months post-diagnosis. Current treatment modalities are limited and only modestly increase survival time. Effective therapeutic alternatives are urgently needed. The purinergic P2X7 receptor (P2X7R) is activated within the glioblastoma microenvironment and evidence suggests it contributes to tumour growth. Studies have implicated P2X7R involvement in a range of neoplasms, including glioblastomas, although the roles of P2X7R in the tumour milieu remain unclear. Here, we report a trophic, tumour-promoting role of P2X7R activation in both patient-derived primary glioblastoma cultures and the U251 human glioblastoma cell line, and demonstrate its inhibition reduces tumour growth in vitro. Primary glioblastoma and U251 cell cultures were treated with the specific P2X7R antagonist, AZ10606120 (AZ), for 72 h. The effects of AZ treatment were also compared to cells treated with the current first-line chemotherapeutic drug, temozolomide (TMZ), and a combination of both AZ and TMZ. P2X7R antagonism by AZ significantly depleted glioblastoma cell numbers compared to untreated cells, in both primary glioblastoma and U251 cultures. Notably, AZ treatment was more effective at tumour cell killing than TMZ. No synergistic effect between AZ and TMZ was observed. AZ treatment also significantly increased lactate dehydrogenase release in primary glioblastoma cultures, suggesting AZ-induced cellular cytotoxicity. Our results reveal a trophic role of P2X7R in glioblastoma. Importantly, these data highlight the potential for P2X7R inhibition as a novel and effective alternative therapeutic approach for patients with lethal glioblastomas.
Asunto(s)
Adamantano , Glioblastoma , Antagonistas del Receptor Purinérgico P2X , Humanos , Adamantano/análogos & derivados , Adamantano/farmacología , Aminoquinolinas/farmacología , Glioblastoma/tratamiento farmacológico , Receptores Purinérgicos P2X7 , Temozolomida/farmacología , Microambiente Tumoral , Antagonistas del Receptor Purinérgico P2X/farmacologíaRESUMEN
Colonization by the microbiota provides one of our most effective barriers against infection by pathogenic microbes. The microbiota protects against infection by priming immune defenses, by metabolic exclusion of pathogens from their preferred niches, and through direct antimicrobial antagonism. Disruption of the microbiota, especially by antibiotics, is a major risk factor for bacterial pathogen colonization. Restoration of the microbiota through microbiota transplantation has been shown to be an effective way to reduce pathogen burden in the intestine but comes with a number of drawbacks, including the possibility of transferring other pathogens into the host, lack of standardization, and potential disruption to host metabolism. More refined methods to exploit the power of the microbiota would allow us to utilize its protective power without the drawbacks of fecal microbiota transplantation. To achieve this requires detailed understanding of which members of the microbiota protect against specific pathogens and the mechanistic basis for their effects. In this review, we will discuss the clinical and experimental evidence that has begun to reveal which members of the microbiota protect against some of the most troublesome antibiotic-resistant pathogens: Klebsiella pneumoniae, vancomycin-resistant enterococci, and Clostridioides difficile.
Asunto(s)
Clostridioides difficile , Microbiota , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Klebsiella pneumoniaeRESUMEN
The microbiota primes immune defences but the identity of specific commensal microorganisms that protect against infection is unclear. Conversely, how pathogens compete with the microbiota to establish their host niche is also poorly understood. In the present study, we investigate the antagonism between the microbiota and Klebsiella pneumoniae during colonization and transmission. We discover that maturation of the microbiota drives the development of distinct immune defence programmes in the upper airways and intestine to limit K. pneumoniae colonization within these niches. Immune protection in the intestine depends on the development of Bacteroidetes, interleukin (IL)-36 signalling and macrophages. This effect of Bacteroidetes requires the polysaccharide utilization locus of their conserved commensal colonization factor. Conversely, in the upper airways, Proteobacteria prime immunity through IL-17A, but K. pneumoniae overcomes these defences through encapsulation to effectively colonize this site. Ultimately, we find that host-to-host spread of K. pneumoniae occurs principally from its intestinal reservoir, and that commensal-colonization-factor-producing Bacteroidetes are sufficient to prevent transmission between hosts through IL-36. Thus, our study provides mechanistic insight into when, where and how commensal Bacteroidetes protect against K. pneumoniae colonization and contagion, providing insight into how these protective microorganisms could be harnessed to confer population-level protection against K. pneumoniae infection.
Asunto(s)
Bacteroidetes/inmunología , Interleucina-1/inmunología , Infecciones por Klebsiella/prevención & control , Klebsiella pneumoniae , Microbiota/inmunología , Animales , Animales Recién Nacidos , Microbioma Gastrointestinal/inmunología , Interacciones Microbiota-Huesped/inmunología , Interleucina-17/inmunología , Infecciones por Klebsiella/inmunología , Infecciones por Klebsiella/transmisión , Klebsiella pneumoniae/patogenicidad , Ratones , Modelos Biológicos , Sistema Respiratorio/inmunología , Sistema Respiratorio/microbiología , Transducción de Señal/inmunologíaRESUMEN
The microbiota promotes resistance to respiratory infection, but the mechanistic basis for this is poorly defined. Here, we identify members of the microbiota that protect against respiratory infection by the major human pathogens Streptococcus pneumoniae and Klebsiella pneumoniae. We show that the microbiota enhances respiratory defenses via granulocyte-macrophage colony-stimulating factor (GM-CSF) signaling, which stimulates pathogen killing and clearance by alveolar macrophages through extracellular signal-regulated kinase signaling. Increased pulmonary GM-CSF production in response to infection is primed by the microbiota through interleukin-17A. By combining models of commensal colonization in antibiotic-treated and germ-free mice, using cultured commensals from the Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria phyla, we found that potent Nod-like receptor-stimulating bacteria in the upper airway (Staphylococcus aureus and Staphylococcus epidermidis) and intestinal microbiota (Lactobacillus reuteri, Enterococcus faecalis, Lactobacillus crispatus and Clostridium orbiscindens) promote resistance to lung infection through Nod2 and GM-CSF. Our data reveal the identity, location, and properties of bacteria within the microbiota that regulate lung immunity, and delineate the host signaling axis they activate to protect against respiratory infection.
Asunto(s)
Factor Estimulante de Colonias de Granulocitos y Macrófagos/metabolismo , Microbiota/fisiología , Infecciones del Sistema Respiratorio/fisiopatología , Transducción de Señal , Animales , Células HEK293 , Humanos , Interleucina-17/metabolismo , Klebsiella pneumoniae/fisiología , Pulmón/metabolismo , Pulmón/microbiología , Macrófagos Alveolares/metabolismo , Macrófagos Alveolares/microbiología , Ratones Endogámicos C57BL , Ratones Noqueados , Interacciones Microbianas/fisiología , Infecciones del Sistema Respiratorio/metabolismo , Infecciones del Sistema Respiratorio/microbiología , Streptococcus pneumoniae/fisiologíaRESUMEN
Staphylococcus aureus is an opportunistic pathogen that produces many virulence factors. Two major families of which are the staphylococcal superantigens (SAgs) and the Staphylococcal Superantigen-Like (SSL) exoproteins. The former are immunomodulatory toxins that induce a Vß-specific activation of T cells, while the latter are immune evasion molecules that interfere with a wide range of innate immune defences. The superantigenic properties of Staphylococcal enterotoxin-like X (SElX) have recently been established. We now reveal that SElX also possesses functional characteristics of the SSLs. A region of SElX displays high homology to the sialyl-lactosamine (sLacNac)-specific binding site present in a sub-family of SSLs. By analysing the interaction of SElX with sLacNac-containing glycans we show that SElX has an equivalent specificity and host cell binding range to the SSLs. Mutation of key amino acids in this conserved region affects the ability of SElX to bind to cells of myeloid origin and significantly reduces its ability to protect S. aureus from destruction in a whole blood killing (WBK) assay. Like the SSLs, SElX is up-regulated early during infection and is under the control of the S. aureus exotoxin expression (Sae) two component gene regulatory system. Additionally, the structure of SElX in complex with the sLacNac-containing tetrasaccharide sialyl Lewis X (sLeX) reveals that SElX is a unique single-domain SAg. In summary, SElX is an 'SSL-like' SAg.
Asunto(s)
Enterotoxinas/metabolismo , Exotoxinas/metabolismo , Evasión Inmune/inmunología , Infecciones Estafilocócicas/metabolismo , Staphylococcus aureus/metabolismo , Factores de Virulencia/metabolismo , Animales , Células Cultivadas , Humanos , Ratones , Infecciones Estafilocócicas/inmunología , Superantígenos/genética , Factores de Virulencia/genéticaRESUMEN
Staphylococcus aureus is a prevalent and significant human pathogen. Among the repertoire of virulence factors produced by this bacterium are the 14 staphylococcal superantigen-like (SSL) proteins. SSL protein 4 (SSL4) is one member of this family and contains a highly conserved carbohydrate binding site also found in SSL2, SSL3, SSL5, SSL6, and SSL11. Recombinant SSL4(t), comprising amino acids 109 to 309 of Newman strain SSL4 (SSL4-Newman), has been shown to bind and be internalized by human granulocytes and macrophages in a sialic-acid (Sia)-dependent manner. SSL4(t) can compete with itself for cell binding, indicating that binding is target specific. A 2.5-Å-resolution crystal structure of SSL4(t) complexed with sialyl Lewis X (sLe(x)) [sLe(x)-Neu5Acα2-3Galß1-4(Fucα1-3)GlcNAc] revealed a similar binding site to SSL5 and SSL11. These data, along with data on SSL4(t) binding to a glycan array and biosensor analysis of sLe(x) and sialyllactosamine (sLacNac) binding are compared with those for SSL11. Although these proteins show great similarity in their carbohydrate binding sites, with a root mean square (RMS) difference between main chain atom positions of only 0.34 Å, these proteins differ in detail in their affinity for sLe(x) and sLacNac, as well as their glycan preference. Together with cell binding data, this shows how S. aureus produces multiple related proteins that target myeloid cells through specific sialyllactosamine-containing glycoproteins.