RESUMEN
Macrophages reside in the body cavities where they maintain serosal homeostasis and provide immune surveillance. Peritoneal macrophages are implicated in the etiology of pathologies including peritonitis, endometriosis, and metastatic cancer; thus, understanding the factors that govern their behavior is vital. Using a combination of fate mapping techniques, we have investigated the impact of sex and age on murine peritoneal macrophage differentiation, turnover, and function. We demonstrate that the sexually dimorphic replenishment of peritoneal macrophages from the bone marrow, which is high in males and very low in females, is driven by changes in the local microenvironment that arise upon sexual maturation. Population and single-cell RNA sequencing revealed marked dimorphisms in gene expression between male and female peritoneal macrophages that was, in part, explained by differences in composition of these populations. By estimating the time of residency of different subsets within the cavity and assessing development of dimorphisms with age and in monocytopenic Ccr2 -/- mice, we demonstrate that key sex-dependent features of peritoneal macrophages are a function of the differential rate of replenishment from the bone marrow, whereas others are reliant on local microenvironment signals. We demonstrate that the dimorphic turnover of peritoneal macrophages contributes to differences in the ability to protect against pneumococcal peritonitis between the sexes. These data highlight the importance of considering both sex and age in susceptibility to inflammatory and infectious diseases.
Asunto(s)
Macrófagos Peritoneales/inmunología , Caracteres Sexuales , Animales , Diferenciación Celular/inmunología , Femenino , Homeostasis/inmunología , Masculino , Ratones , Ratones Congénicos , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Noqueados , Fenotipo , ARN/genética , ARN/inmunología , Análisis de Secuencia de ARN , Análisis de la Célula IndividualRESUMEN
Hypoxia and bacterial infection frequently co-exist, in both acute and chronic clinical settings, and typically result in adverse clinical outcomes. To ameliorate this morbidity, we investigated the interaction between hypoxia and the host response. In the context of acute hypoxia, both S. aureus and S. pneumoniae infections rapidly induced progressive neutrophil mediated morbidity and mortality, with associated hypothermia and cardiovascular compromise. Preconditioning animals through longer exposures to hypoxia, prior to infection, prevented these pathophysiological responses and profoundly dampened the transcriptome of circulating leukocytes. Specifically, perturbation of HIF pathway and glycolysis genes by hypoxic preconditioning was associated with reduced leukocyte glucose utilisation, resulting in systemic rescue from a global negative energy state and myocardial protection. Thus we demonstrate that hypoxia preconditions the innate immune response and determines survival outcomes following bacterial infection through suppression of HIF-1α and neutrophil metabolism. The therapeutic implications of this work are that in the context of systemic or tissue hypoxia therapies that target the host response could improve infection associated morbidity and mortality.
RESUMEN
Alveolar macrophages play an essential role in clearing bacteria from the lower airway, as the resident phagocyte alveolar macrophages must both phagocytose and kill bacteria, and if unable to do this completely must co-ordinate an inflammatory response. The decision to escalate the inflammatory response represents the transition between subclinical infection and the development of pneumonia. Alveolar macrophages are well equipped to phagocytose bacteria and have a large phagolysosomal capacity in which ingested bacteria are killed. The rate-limiting step in control of extracellular bacteria, such as Streptococcus pneumoniae, is the capacity of alveolar macrophages to kill ingested bacteria. Therefore, alveolar macrophages complement canonical microbicidal strategies with an additional level of apoptosis-associated killing to help kill ingested bacteria.
Asunto(s)
Proteínas del Sistema Complemento/inmunología , Macrófagos Alveolares/inmunología , Infecciones Neumocócicas/inmunología , Neumonía/inmunología , Streptococcus pneumoniae/inmunología , Animales , Apoptosis/inmunología , Enfermedades Asintomáticas , Bacteriólisis , Progresión de la Enfermedad , Humanos , Inmunidad Activa , Espacio Intracelular/inmunología , Activación de Macrófagos , Fagocitosis/inmunología , Infecciones Neumocócicas/complicaciones , Neumonía/etiologíaRESUMEN
HIV-1 can establish both long lived and productive infection of macrophages (MÏ) but circulating monocytes are less permissive to infection. Multiple studies have identified extensive changes to monocyte and MÏ phenotype, differentiation or function. These include alterations in Toll-like receptor signaling and resultant changes to cytokine responses, specific defects in phagocytosis and microbial killing and modulation of apoptotic responses, all of which may perturb the important role of these cells in innate immunity. Interpretation of contradictory data however, is complicated by the use of different experimental models and many of the reported effects may be an indirect consequence of HIV 1 infection that result from exposure to viral products or from disruption of cellular and cytokine networks in the immune system, rather than the direct consequence of productive HIV 1 infection. Future research should focus on refining experimental models and on elucidating the physiological mechanisms of monocyte/ MÏ dysfunction during HIV 1 infection.
Asunto(s)
Infecciones por VIH/inmunología , VIH-1 , Inmunidad Innata/inmunología , Macrófagos/inmunología , Monocitos/inmunología , Animales , Apoptosis , Infecciones por VIH/virología , Humanos , Modelos Biológicos , Fagocitosis , Transducción de Señal , Receptores Toll-Like/metabolismoRESUMEN
Invasive aspergillosis (IA) makes a marked contribution to the mortality of immunocompromised hosts, especially those who have received cytotoxic chemotherapy for haematological malignancy or allogeneic haemopoietic stem cell transplantation. Salvage therapy, in the case of invasive fungal infection, generally refers to the treatment of infected individuals who are refractory or intolerant to initial therapy administered for at least 7 days. Although clinical trials of salvage therapy of IA have been undertaken, most were non-comparator studies or contained a non-randomized control group, and criteria for patient enrollment and the methods used to assess response were variable. Salvage therapy has produced relatively disappointing results, emphasizing the importance of early diagnosis and effective primary therapy for IA. Despite this, a number of agents have been studied in the treatment of IA and have demonstrated efficacy in a salvage setting. These include lipid-based formulations of amphotericin B, caspofungin, itraconazole, voriconazole, posaconazole and micafungin. Combinations of echinocandins with either azoles or amphotericin B have also been studied in small series. Further studies are required, ideally comparing newer agents and treatment strategies in randomized clinical trials, to clarify the optimal approach to salvage treatment of IA in this challenging group of patients.
Asunto(s)
Aspergilosis/terapia , Terapia Recuperativa/métodos , Antifúngicos/farmacología , Antifúngicos/uso terapéutico , Aspergilosis/patología , Farmacorresistencia Fúngica/efectos de los fármacos , Farmacorresistencia Fúngica/fisiología , Humanos , Terapia Recuperativa/tendenciasRESUMEN
Invasive fungal infections cause substantial morbidity and mortality in immunocompromised hosts. The response rate to therapy, in particular for invasive aspergillosis and invasive mould infections, has been poor. Recently a number of techniques to facilitate early diagnosis of these infections, in parallel with the development of a number of antifungals with increased potency and lower toxicity, have raised optimism that outcomes for invasive fungal infection can be improved upon. The availability of lipid formulations of amphotericin B, azoles with extended spectrum against filamentous fungi and the development of a new class of antifungal agents, the echinocandins, presents the clinician with a range of therapeutic choices. Recent clinical trials have provided important insights into how these agents should be used. In particular, voriconazole has demonstrated superior efficacy to amphotericin B in the management of invasive aspergillosis, posaconazole has been shown to have significant efficacy in the prophylaxis of invasive fungal infection in high-risk individuals and a role in salvage therapy of invasive aspergillosis, caspofungin has demonstrated efficacy in salvage therapy of invasive aspergillosis, and each of the echinocandins show activity without significant toxicity in invasive candidiasis. Nevertheless, many therapeutic areas of uncertainty remain, including the role of combination therapy, and will provide the focus for future studies.
Asunto(s)
Antifúngicos/uso terapéutico , Huésped Inmunocomprometido , Micosis/tratamiento farmacológico , Anfotericina B/uso terapéutico , Azoles/uso terapéutico , Combinación de Medicamentos , Humanos , Micosis/diagnóstico , Péptidos Cíclicos/uso terapéutico , Fosfatidilcolinas/uso terapéutico , Fosfatidilgliceroles/uso terapéutico , Resultado del TratamientoRESUMEN
OBJECTIVES: Invasive pneumococcal disease (IPD) is associated with a high mortality despite antimicrobial therapy, but may be preventable by pneumococcal vaccination. The extent of previous exposure to pneumococcal capsular polysaccharide vaccination prior to an episode of IPD in hospitalised adults in the United Kingdom is unclear. METHODS: We conducted a retrospective cohort study in adults with IPD admitted to either of two teaching hospitals in Sheffield, United Kingdom during 1992-2000. Receipt of pneumococcal vaccination, risk factors for IPD, death and disability were determined. RESULTS: The number of cases of IPD was 552 and 187/230 patient records from one site were reviewed. According to UK pneumococcal vaccination guidelines 59% of patients should have received the vaccine and 76% of patients if updated guidelines, which include age>65 years as an indication, are applied. In patients with known risk factors, excluding age, only 8% had been vaccinated. The mortality from IPD was 21% and an additional 6% suffered major complications. CONCLUSIONS: In patients hospitalised with IPD there is a high rate of pre-existing risk factors and a low rate of administration of pneumococcal vaccination. IPD incurs significant mortality, morbidity and economic cost and there is potential for reducing this by improved uptake of pneumococcal vaccination.
Asunto(s)
Infecciones Neumocócicas/prevención & control , Vacunas Neumococicas/administración & dosificación , Streptococcus pneumoniae , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Infecciones Neumocócicas/epidemiología , Infecciones Neumocócicas/microbiología , Factores de Riesgo , Streptococcus pneumoniae/inmunología , Streptococcus pneumoniae/aislamiento & purificación , Reino Unido/epidemiología , VacunaciónRESUMEN
We present a case where alopecia occurred with severe seborrhoeic dermatitis associated with the commencement of combination antiretroviral therapy for acute retroviral syndrome. We postulate that the eruption could represent a novel manifestation in association with immunological response to antiretroviral therapy.
Asunto(s)
Alopecia/inducido químicamente , Terapia Antirretroviral Altamente Activa/efectos adversos , Dermatitis Seborreica/inducido químicamente , Infecciones por VIH/tratamiento farmacológico , Administración Tópica , Adulto , Alopecia/tratamiento farmacológico , Alopecia/fisiopatología , Terapia Antirretroviral Altamente Activa/métodos , Betametasona/uso terapéutico , Aceite de Coco , Dermatitis Seborreica/tratamiento farmacológico , Dermatitis Seborreica/fisiopatología , Quimioterapia Combinada , Estudios de Seguimiento , Infecciones por VIH/diagnóstico , Humanos , Masculino , Aceites de Plantas/uso terapéutico , Medición de Riesgo , Ácido Salicílico/uso terapéutico , Índice de Severidad de la Enfermedad , Resultado del TratamientoRESUMEN
Fas ligand (FasL) is a type II transmembrane protein that plays a critical role in immune homeostasis by binding to its receptor Fas (CD95) and inducing apoptosis. Fas/FasL dysregulation contributes to infectious disease pathogenesis. Microorganisms may inhibit Fas signal transduction to prolong intracellular survival and prevent killing by immune effector cells. FasL may be upregulated in directly infected cells to enhance killing of responding immune cells and facilitate immune evasion. The host response to infection may aim to induce apoptosis in directly infected cells, but immune cells that target directly infected cells can induce Fas-mediated apoptosis of uninfected bystander cells. FasL also contributes to the generation and regulation of the inflammatory response in infection. The multiple roles of FasL in infectious disease pathogenesis are discussed in the context of viral, bacterial and parasitic infections.
Asunto(s)
Infecciones/etiología , Glicoproteínas de Membrana/fisiología , Síndrome de Inmunodeficiencia Adquirida/etiología , Síndrome de Inmunodeficiencia Adquirida/inmunología , Animales , Apoptosis , Infecciones Bacterianas/etiología , Infecciones Bacterianas/inmunología , Proteína Ligando Fas , VIH-1/inmunología , Humanos , Infecciones/inmunología , Infecciones por Mycobacterium/etiología , Infecciones por Mycobacterium/inmunología , Transducción de Señal , Virosis/etiología , Virosis/inmunología , Receptor fas/fisiologíaRESUMEN
Apoptosis is a key event in biologic homeostasis with particular importance to the immune system. It is an active energy-dependent process that is tightly regulated and controlled by a variety of signal transduction pathways. Apoptosis modulation plays a part in the pathogenesis of many human diseases, including HIV infection. Although multiple mechanisms may contribute to the decline in CD4 T-lymphocyte numbers observed, apoptosis is a significant factor. Alterations in levels of apoptosis are observed in both directly infected and uninfected bystander cells and a variety of pathways of apoptosis induction have been implicated. Apoptosis induction is related to death receptor and mitochondrial-induced pathways in specific circumstances. These events have been linked to individual HIV proteins and have been demonstrated to be altered by antiretroviral therapy.
Asunto(s)
Apoptosis , Linfocitos T CD4-Positivos/inmunología , Infecciones por VIH/inmunología , VIH-1 , Infecciones por VIH/patología , HumanosRESUMEN
Human herpesvirus 6 (HHV-6) exists as distinct variants HHV-6A and HHV-6B. The complete genomes of HHV-6A and HHV-6B have been sequenced. HHV-6B contains 97 unique genes. CD46 is the cell receptor for HHV-6, explaining its broad tissue tropism but its restricted host-species range. HHV-6 utilizes a number of strategies to down-regulate the host immune response, including molecular mimicry by production of a functional chemokine and chemokine receptors. Immunosuppression is enhanced by depletion of CD4 T lymphocytes via direct infection of intra-thymic progenitors and by apoptosis induction. Infection is widespread in infants between 6 months and 2 years of age. A minority of infants develop roseola infantum, but undifferentiated febrile illness is more common. Reactivation from latency occurs in immunocompromised hosts. Organ-specific clinical syndromes occasionally result, but indirect effects including interactions with other viruses such as human immunodeficiency virus type 1 and human cytomegalovirus or graft dysfunction in transplant recipients may be more significant complications in this population. Recent advances in quantitative PCR are providing additional insights into the natural history of infection in paediatric populations and immunocompromised hosts.
Asunto(s)
Herpesvirus Humano 6 , Infecciones por Roseolovirus , Regulación Viral de la Expresión Génica , Herpesvirus Humano 6/genética , Herpesvirus Humano 6/inmunología , Herpesvirus Humano 6/fisiología , Humanos , Huésped Inmunocomprometido , Infecciones por Roseolovirus/diagnóstico , Infecciones por Roseolovirus/epidemiología , Infecciones por Roseolovirus/inmunología , Infecciones por Roseolovirus/virologíaAsunto(s)
Disnea/parasitología , Agua Dulce/parasitología , Hipertensión Pulmonar/parasitología , Leptospira interrogans , Leptospirosis/diagnóstico , Enfermedad Aguda , Adulto , Antibacterianos/efectos adversos , Ecocardiografía Transesofágica , Electrocardiografía , Inglaterra , Fiebre/parasitología , Cefalea/parasitología , Humanos , Hipotensión/inducido químicamente , Irlanda , Leptospira interrogans/clasificación , Leptospirosis/complicaciones , Leptospirosis/tratamiento farmacológico , Masculino , Náusea/parasitología , Serotipificación , NataciónRESUMEN
Augmenting the host's natural immune response to viruses by the administration of exogenous cytokines such as interferon-alpha (IFN-alpha) is a strategy increasingly employed in antiviral therapeutics. Enhancing the release of endogenous cytokines is, however, an alternative approach. The imidazoquinolinamines imiquimod and resiquimod have demonstrated potency as inducers of IFN-alpha and other cytokines both in vitro and in vivo. Cytokine gene activation is mediated via the signal transducer and activator of transcription 1 (STAT-1) and involves the transcription factors NFkappaB and alpha4F1. Antiviral activity has been demonstrated against a variety of viruses, and clinical efficacy has been demonstrated against genital warts, herpes genitalis and molluscum contagiosum. Imiquimod is administered as a 5% cream (Aldara) and has been licensed for the treatment of anogenital warts in immunocompetent patients. Complete clearance of warts has been observed in up to half of treated patients with only local side effects reported. Resiquimod can be administered topically but also exists as an oral formulation. The range of potential infections for which these agents may have clinical utility includes chronic hepatitis C virus infection and Kaposi's sarcoma. In addition, the imidazoquinolinamines may find roles in the therapy of cancers and as vaccine adjuvants.
Asunto(s)
Adyuvantes Inmunológicos/uso terapéutico , Aminoquinolinas/uso terapéutico , Imidazoles/uso terapéutico , Adyuvantes Inmunológicos/química , Aminoquinolinas/química , Animales , Humanos , Imidazoles/química , Imiquimod , Factores Inmunológicos/química , Factores Inmunológicos/uso terapéuticoRESUMEN
Apoptosis is a physiological process critical for tissue homeostasis. It is essential for the regulation of immune responses. A series of molecules transduce apoptoic signals and induce the characteristic morphological appearances of apoptotic cells. Infectious diseases modulate apoptosis and this contributes to disease pathogenesis. Infection with HIV results in enhanced levels of CD4 T-lymphocyte apoptosis in both directly infected cells and in uninfected bystander cells. A variety of HIV proteins including gp120 contribute to this process. A number of different pathways induce HIV-associated CD4 T-lymphocyte apoptosis and apoptosis of uninfected bystander cells is particularly associated with increased susceptibility to Fas. Other viruses including hepatitis viruses and the human herpesviruses also modulate apoptosis. Bacterial infection induces apoptosis which is frequently mediated by the direct activation of caspases in the absence of death receptor ligation. Bacterial induction of apoptosis may either be due to bacterial factors such as the invasin IpaB of Shigella flexneri or be the result of host immune responses which control infection as demonstrated in infections due to Mycobacterium spp. Apoptosis may be modulated by therapeutic strategies, such as antiretroviral therapy, and an improved understanding of infection-associated apoptosis modulation will aid the design of novel therapeutic approaches to control infectious diseases.
Asunto(s)
Apoptosis , Enfermedades Transmisibles/metabolismo , Apoptosis/inmunología , Linfocitos T CD4-Positivos/metabolismo , Enfermedades Transmisibles/enzimología , Enfermedades Transmisibles/inmunología , Infecciones por VIH/metabolismo , Humanos , Virosis/metabolismoRESUMEN
Apoptosis of macrophages may be a pathogen-directed mechanism of immune escape or may represent appropriate host response to infection. Human monocyte-derived macrophages (MDMs) from healthy donors (C-MDMs) exhibited low-level constitutive apoptosis, but culture of MDMs with opsonized serotype I Streptococcus pneumoniae (I-MDMs) for 20 h resulted in significantly increased apoptosis. I-MDM apoptosis was associated with phagocytosis of bacteria and intracellular killing that was blocked by the caspase inhibitor z-VAD-fmk but not by Fas-blocking antibody. Paraformaldehyde-fixed I-MDMs induced apoptosis in uninfected syngeneic monocytes at levels greater than those in monocytes incubated alone or incubated with fixed C-MDMs. Apoptosis of syngeneic monocytes was blocked by anti-Fas antibody. The immune response of macrophages to S. pneumoniae includes a novel form of apoptosis that is associated with successful phagocytosis and bacterial killing. This response in vivo may regulate the inflammatory response to infection during a successful host response against S. pneumoniae.