RESUMEN
A cancer diagnosis in young adulthood disrupts the achievement of developmental milestones, and young adults struggle to make sense of their cancer experience due to a lack of opportunities to both openly talk about cancer and engage in reflective activities. However, entertainment narratives - or stories - may be an alternative to prompt these activities, as narratives can elicit self-expansion that may help fulfill intrinsic needs. One way to think about these narratives is as memorable messages. These messages stick with a person for a long period of time, have an anticipatory socialization effect, and may prompt the sense-making process through narrative communication. Little is known, though, about the use of entertainment narratives among young adults with cancer. We interviewed 25 young adults with cancer about entertainment narratives that were memorable during their cancer experience and how those narratives affected them. From these in-depth, semi-structured interviews, we found that entertainment narratives were generally helpful if they provided distraction from cancer, were relatable, and/or prompted participants to explore their emotions. We found that entertainment narratives were generally harmful if they worsened participants' emotional state, either by exacerbating fears of death and/or depicting cancer unrealistically. Our findings suggest that entertainment narratives are memorable messages, and that helpful messages increased feelings of competence and validation, which could promote psychological adaptation to the disease. Harmful messages increased fear and invalidated participants' difficult experiences, which could lead to greater illness centrality and internalized stigma. Implications for future research are discussed.
Asunto(s)
Narración , Neoplasias , Humanos , Adulto Joven , Adulto , Comunicación , Emociones , SocializaciónRESUMEN
BACKGROUND: Web-based social support can address social isolation and unmet support needs among young adults with cancer (aged 18-39 years). Given that 94% of young adults own and use smartphones, social media can offer personalized, accessible social support among peers with cancer. OBJECTIVE: This study aims to examine the specific benefits, downsides, and topics of social support via social media among young adults with cancer. METHODS: We conducted semistructured interviews with young adults with cancer, aged between 18 and 39 years, who were receiving treatment or had completed treatment for cancer. RESULTS: Most participants (N=45) used general audience platforms (eg, Facebook groups), and some cancer-specific social media (eg, Caring Bridge), to discuss relevant lived experiences for medical information (managing side effects and treatment uncertainty) and navigating life with cancer (parenting and financial issues). Participants valued socializing with other young adults with cancer, making connections outside their personal networks, and being able to validate their emotional and mental health experiences without time and physical constraints. However, using social media for peer support can be an emotional burden, especially when others post disheartening or harassing content, and can heighten privacy concerns, especially when navigating cancer-related stigma. CONCLUSIONS: Social media allows young adults to connect with peers to share and feel validated about their treatment and life concerns. However, barriers exist for receiving support from social media; these could be reduced through content moderation and developing more customizable, potentially cancer-specific social media apps and platforms to enhance one's ability to find peers and manage groups.
RESUMEN
PURPOSE: Social isolation is a prominent challenge for many young adults with cancer. Despite desires for peer-to-peer connections through technology, little is known about how young adults initiate or use social media for support over time. METHODS: We interviewed young adults with cancer (n = 45; age 18-39, in or post cancer treatment) to explore their initiation of social media for support, changes in use over time, and types of connections sought. RESULTS: Young adults with cancer learn about online support through individual personal recommendations, advocacy organizations, or searching on Google or social media. Most were reluctant to use social media support initially because of feeling overwhelmed-from diagnoses, abundance of online information, or demands of participation-and joined when informational and emotional needs arose. Many wished they had joined earlier. Some participants use social media to make close connections while others simply want to "see" others' shared experiences or crowdsource information. CONCLUSION: Young adults with cancer often haphazardly find online support from personal recommendations or Internet searches. Desires for social media connections are not one-size-fits-all; there are important audience segmentations for the degree and type of peer support. IMPLICATIONS FOR CANCER SURVIVORS: Better promotion of online social support options and benefits-early in one's cancer timeline and systematically through healthcare providers, cancer organizations, or family and friends-could improve access to helpful peer-to-peer support.
Asunto(s)
Neoplasias , Medios de Comunicación Sociales , Adolescente , Adulto , Humanos , Internet , Neoplasias/terapia , Grupo Paritario , Apoyo Social , Sobrevivientes , Adulto JovenRESUMEN
Monophosphoryl lipid A (MPLA) is a Toll-like receptor 4 (TLR4) agonist that is currently used as a vaccine adjuvant in humans. In this study, we evaluated the effect of MPLA treatment on the innate immune response to systemic bacterial infections in mice. Mice treated with MPLA after burn injury showed improved survival and less local and systemic dissemination of bacteria in a model of Pseudomonas aeruginosa burn wound infection. Prophylactic treatment with MPLA significantly enhanced bacterial clearance at the site of infection and reduced systemic dissemination of bacteria despite causing attenuation of proinflammatory cytokine production during acute intra-abdominal infection caused by cecal ligation and puncture. Administration of MPLA at 1 h after CLP also improved bacterial clearance but did not alter cytokine production. MPLA treatment increased the numbers of granulocytes, double-positive myeloid cells, and macrophages at sites of infection and increased the percentage and total numbers of myeloid cells mediating phagocytosis of bacteria. Depletion of Ly6G(+) neutrophils, but not macrophages, eliminated the ability of MPLA treatment to improve bacterial clearance. The immunomodulatory effects of MPLA were absent in TLR4-deficient mice. In conclusion, these studies show that MPLA treatment significantly augments the innate immune response to bacterial infection by enhancing bacterial clearance despite the attenuation of proinflammatory cytokine production. The enhanced bacterial clearance is mediated, in part, by increased numbers of myeloid cells with effective phagocytic functions at sites of infection and is TLR4 dependent.
Asunto(s)
Inmunidad Innata , Lípido A/análogos & derivados , Infecciones por Pseudomonas/inmunología , Pseudomonas aeruginosa/inmunología , Receptor Toll-Like 4/agonistas , Infección de Heridas/inmunología , Animales , Quemaduras/inmunología , Citocinas/biosíntesis , Femenino , Lípido A/administración & dosificación , Lípido A/farmacología , Recuento de Linfocitos , Macrófagos/inmunología , Masculino , Ratones , Ratones Endogámicos C3H , Ratones Endogámicos C57BL , Neutrófilos/inmunología , Infecciones por Pseudomonas/tratamiento farmacológico , Infecciones por Pseudomonas/microbiología , Transducción de Señal , Receptor Toll-Like 4/genética , Receptor Toll-Like 4/inmunología , Infección de Heridas/tratamiento farmacológico , Infección de Heridas/microbiologíaRESUMEN
The present study was undertaken to determine whether the mice depleted of alphabeta or gammadelta T cells show resistance to acute polymicrobial sepsis caused by cecal ligation and puncture (CLP). T-cell receptor beta knockout (betaTCRKO) and T-cell receptor delta knockout (deltaTCRKO) mice were used. An additional group of mice was treated with an antibody against the alphabeta T-cell receptor to induce alphabeta T-cell depletion; a subset of alphabeta T cell-deficient mice was also treated with anti-asialoGM1 to deplete natural killer (NK) cells. The mice underwent CLP and were monitored for survival, temperature, acid-base balance, bacterial counts, and cytokine production. The betaTCRKO mice and the wild-type mice treated with anti-beta T-cell receptor (anti-TCRbeta) antibody showed improved survival after CLP compared with wild-type mice. The treatment of alphabeta T cell-deficient mice with anti-asialoGM1further improved survival after CLP, especially when the mice were treated with imipenem. The improved survival observed in alphabeta T cell-deficient mice was associated with less hypothermia, improved acid-base balance, and decreased production of the proinflammatory cytokines interleukin (IL) 6 and macrophage inflammatory protein (MIP) 2. Compared with wild-type controls, the overall survival was not improved in deltaTCRKO mice. The concentrations of IL-6 and MIP-2 in plasma and cytokine mRNA expression in tissues were not significantly different between wild-type and deltaTCRKO mice. These studies indicate that mice depleted of alphabeta but not of gammadelta T cells are resistant to mortality in an acutely lethal model of CLP. The depletion of NK cells caused further survival benefit in alphabeta T cell-deficient mice. These findings suggest that alphabeta T and NK cells mediate or facilitate CLP-induced inflammatory injury.
Asunto(s)
Ciego/lesiones , Receptores de Antígenos de Linfocitos T alfa-beta/deficiencia , Receptores de Antígenos de Linfocitos T gamma-delta/deficiencia , Linfocitos T/inmunología , Animales , Antibacterianos/uso terapéutico , Bacteriemia/tratamiento farmacológico , Bacteriemia/inmunología , Bacteriemia/mortalidad , Bacterias/efectos de los fármacos , Bacterias/crecimiento & desarrollo , Quimiocina CXCL2 , Ensayo de Inmunoadsorción Enzimática , Femenino , Citometría de Flujo , Imipenem/uso terapéutico , Interleucina-6/metabolismo , Células Asesinas Naturales/efectos de los fármacos , Células Asesinas Naturales/inmunología , Células Asesinas Naturales/metabolismo , Ligadura , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Monocinas/metabolismo , Punciones , Receptores de Antígenos de Linfocitos T alfa-beta/genética , Receptores de Antígenos de Linfocitos T alfa-beta/inmunología , Receptores de Antígenos de Linfocitos T gamma-delta/genética , Receptores de Antígenos de Linfocitos T gamma-delta/inmunología , Sepsis/tratamiento farmacológico , Sepsis/inmunología , Sepsis/mortalidad , Linfocitos T/efectos de los fármacos , Linfocitos T/metabolismo , Temperatura , Factores de TiempoRESUMEN
Endotoxin (LPS) tolerance is induced by exposure to sublethal doses of LPS, resulting in a suppressed proinflammatory response and an improved survival rate after challenge with a normally lethal dose of LPS. We studied the effects of tolerance induced by either Escherichia coli-derived LPS or Pseudomonas aeruginosa-derived LPS on the innate immune response to a subsequent P. aeruginosa bacterial challenge and determined if the induction of tolerance was dependent on interferon gamma (IFN-gamma) activity. LPS tolerance was induced in wild-type (WT) and IFN-gamma knockout mice by i.p. injection of 1 microg of LPS on 2 consecutive days. Mice were challenged with an i.p. injection of live P. aeruginosa (1 x 10(8) colony-forming units) 2 days after the second LPS dose. LPS tolerance in WT mice was associated with diminished serum IFN-gamma and IL-12 and increased serum IL-10 responses to the Pseudomonas challenge. Both clearance of the bacterial challenge and survival were improved in WT animals pretreated with either E. coli LPS or P. aeruginosa LPS compared with saline-pretreated control mice. Similarly, IFN-gamma knockout mice exposed to LPS before the Pseudomonas challenge also had improved bacterial clearance of the challenge and an improved survival rate. In separate experiments, priming with IFN-gamma at a dose that approximated the serum concentration induced by LPS priming did not alter cytokine production or bacterial clearance after a Pseudomonas challenge. Finally, administration of IFN-gamma at the time of Pseudomonas challenge amplified cytokine production in LPS-tolerant animals but did not affect bacterial clearance. These results suggest that IFN-gamma is not necessary for the induction of LPS tolerance. Furthermore, IFN-gamma seems to play a role in propagating the inflammatory cytokine response to Pseudomonas challenge, but it did not seem to have any role in bacterial clearance.
Asunto(s)
Interferón gamma/metabolismo , Lipopolisacáridos/farmacología , Infecciones por Pseudomonas/metabolismo , Animales , Citocinas/metabolismo , Endotoxinas/metabolismo , Ensayo de Inmunoadsorción Enzimática , Escherichia coli/metabolismo , Inflamación , Interleucina-10/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Pseudomonas/metabolismo , Pseudomonas aeruginosa/metabolismoRESUMEN
Transforming growth factor-beta (TGF-beta), a cytokine with anti-inflammatory properties, may contribute to postburn immunosuppression. This study was designed to determine whether neutralizing TGF-beta in burned mice could improve resistance to infection. C57BL/6J mice received a 35% TBSA flame burn under isoflurane anesthesia. Four days after injury, mice were treated with TGF-beta antibody or nonspecific IgG. On day 5 after burn injury, mice were inoculated with Pseudomonas aeruginosa at the burn wound site or received intraperitoneal injection with P. aeruginosa. Mice treated with anti-TGF-beta exhibited significantly improved survival compared with mice treated with nonspecific IgG after challenge with P. aeruginosa at the burn wound site or after intraperitoneal injection of P. aeruginosa. In mice with burn wound infections, bacterial counts in burn wounds, blood, and lung were decreased in mice treated with anti-TGF-beta compared with mice treated with control IgG. Bacterial counts in lung and blood after intraperitoneal challenge with P. aeruginosa also were significantly lower in burned mice treated with anti-TGF-beta compared with those treated with nonspecific IgG. Our data suggest that neutralization of TGF-beta at 4 days after burn injury in mice improves local and systemic clearance of P. aeruginosa and enhances survival after P. aeruginosa challenge.
Asunto(s)
Quemaduras/microbiología , Infecciones por Pseudomonas/inmunología , Pseudomonas aeruginosa/aislamiento & purificación , Factor de Crecimiento Transformador beta/antagonistas & inhibidores , Infección de Heridas/inmunología , Animales , Anticuerpos/farmacología , Quemaduras/mortalidad , Recuento de Colonia Microbiana , Femenino , Pulmón/microbiología , Ratones , Ratones Endogámicos C57BL , Modelos Animales , Infecciones por Pseudomonas/metabolismo , Infección de Heridas/microbiologíaRESUMEN
This study was performed to determine whether endotoxemia causes diastolic cardiac dysfunction. Eleven healthy volunteers, 30 +/- 6 years of age, underwent comprehensive transthoracic echocardiographic assessment including two-dimensional, M-mode transmitral and tissue Doppler of systolic and diastolic function at baseline and at 3 and 5 h after intravenous administration of purified Escherichia coli endotoxin (4 ng/kg). Data were analyzed by analysis of variance; P values of less than 0.05 were considered significant. Endotoxin administration resulted in a hyperdynamic state characterized by decreased mean arterial pressure and significant increase in cardiac index. This was accompanied by increases in several load-dependent systolic performance indices (3 and 5 h). Robust increases in peak systolic blood pressure/end-systolic volume index, one of the relatively load-independent contractility parameter, were also observed at 3 h after endotoxin administration. Transmitral peak early velocity (E), which represents early filling, significantly increased at 3 h after infusion. Late diastolic velocity (A), which represents atrial contraction, significantly increased at 3 and 5 h after infusion. The E/A ratio indicative of delayed relaxation significantly decreased due to increases in A (transmitral) and A (tissue Doppler) at 3 and 5 h after infusion. As expected, endotoxin infusion resulted in a hyperdynamic state associated with increases in systolic function indices including endocardial systolic velocities. The observed decreases in E/A (transmitral) and E/A (tissue Doppler) ratio were primarily due to increases in A and A. Moreover, isovolumic relaxation time and time constant for left ventricular relaxation, a load-independent parameter for ventricular relaxation, remained unchanged at 3 and 5 h after endotoxin infusion. Therefore, our findings are more likely due to enhanced atrial contractility resulting from increased sympathetic activity in response to reduction in left ventricular afterload and not due to altered diastolic filling characteristics.
Asunto(s)
Diástole/fisiología , Endotoxinas/fisiología , Sístole/fisiología , Función Ventricular/fisiología , Adulto , Femenino , Ventrículos Cardíacos/metabolismo , Humanos , MasculinoRESUMEN
Our previous studies showed that beta(2)-microglobulin knockout mice treated with anti-asialoGM1 (beta2MKO/alphaAsGM1 mice) are resistant to injury caused by cecal ligation and puncture (CLP). However, CLP-induced injury is complex. Potential mechanisms of injury include systemic infection, cecal ischemia, and translocation of bacterial toxins such as endotoxin and superantigens. Currently, it is unclear which of these mechanisms of injury contributes to mortality in wild-type mice and whether beta2MKO/alphaAsGM1 mice are resistant to any particular mechanisms of injury. In the present study, we hypothesized that systemic infection is the major cause of injury after CLP in wild-type mice and that beta2MKO/alphaAsGM1 mice are resistant to infection-induced injury. To test this hypothesis, wild-type and beta2MKO/alphaAsGM1 mice were treated with the broad-spectrum antibiotic imipenem immediately after CLP to decrease the impact of systemic infection in our model. Treatment of wild-type and beta2MKO/alphaAsGM1 mice with imipenem decreased bacterial counts by at least two orders of magnitude. However, all wild-type mice, whether treated with saline or imipenem, died by 42 h after CLP and had significant hypothermia, metabolic acidosis, and high plasma concentrations of the cytokines interleukin-6, macrophage inflammatory protein-2, and keratinocyte-derived chemokine. beta2MKO/alphaAsGM1 mice showed 40% long-term survival, which was increased to 90% by imipenem treatment. beta2MKO/alphaAsGM1 mice had less hypothermia, decreased metabolic acidosis, and lower cytokine concentrations at 18 h after CLP compared with wild-type mice. These results suggest that infection is not the major cause of mortality for wild-type mice in our model of CLP. Other mechanisms of injury such as cecal ischemia or translocation of microbial toxins may be more important. beta2MKO/alphaAsGM1 mice appear resistant to these early, non-infection-related causes of CLP-induced injury but showed delayed mortality associated with bacterial dissemination, which was ablated by treatment with imipenem.
Asunto(s)
Antibacterianos/farmacología , Ciego/lesiones , Imipenem/farmacología , Células Asesinas Naturales/fisiología , Microglobulina beta-2/genética , Equilibrio Ácido-Base/fisiología , Animales , Ciego/microbiología , Ciego/patología , Recuento de Colonia Microbiana , Citocinas/biosíntesis , Ensayo de Inmunoadsorción Enzimática , Femenino , Ligadura , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Sobrevida , TemperaturaRESUMEN
CD8 knockout mice depleted of natural killer (NK) cells by treatment with anti-asialoGM1 (CD8KO/alphaAsGM1 mice) are resistant to injury caused by cecal ligation and puncture (CLP). However, CLP-induced injury is complex. Potential sources of injury include bacterial dissemination, cecal ischemia, and translocation of bacterial toxins. We treated wild-type and CD8KO/alphaAsGM1 mice with imipenem after CLP to decrease bacterial dissemination. Additional mice were subjected to cecal ligation without puncture of the cecal wall or cecal ligation and removal of cecal contents. Imipenem treatment decreased bacterial counts by at least two orders of magnitude. However, all wild-type mice, whether treated with saline or imipenem, died by 42 h after CLP and exhibited significant hypothermia, metabolic acidosis, and high plasma cytokine concentrations. Wild-type mice subjected to cecal ligation without puncture also died, despite very low bacterial counts in blood, but wild-type mice subjected to cecal ligation and washout of cecal contents survived. In CD8KO/alphaAsGM1 mice subjected to CLP, imipenem treatment increased survival from 50% to 100%. After cecal ligation without puncture, long-term survival was 80-90% in CD8KO/alphaAsGM1 mice. Hypothermia, metabolic acidosis, and cytokine production were attenuated in CD8KO/alphaAsGM1 mice compared with wild-type controls. These results indicate that bacterial dissemination is not a major source of injury in wild-type mice after CLP, but the presence of gut flora in the cecal lumen is required for induction of systemic inflammation after cecal injury. CD8KO/alphaAsGM1 mice are resistant to the systemic manifestations of cecal injury.
Asunto(s)
Traumatismos Abdominales/tratamiento farmacológico , Traumatismos Abdominales/inmunología , Citocinas/inmunología , Imipenem/administración & dosificación , Células Asesinas Naturales/inmunología , Peritonitis/inmunología , Peritonitis/prevención & control , Traumatismos Abdominales/complicaciones , Traumatismos Abdominales/microbiología , Animales , Antibacterianos/administración & dosificación , Infecciones Bacterianas , Antígenos CD8/inmunología , Linfocitos T CD8-positivos/inmunología , Ciego/efectos de los fármacos , Ciego/inmunología , Ciego/microbiología , Femenino , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Peritonitis/etiología , Peritonitis/microbiología , Resultado del TratamientoRESUMEN
Endotoxin (lipopolysaccharide [LPS]) tolerance is an altered state of immunity caused by prior exposure to LPS, in which production of many cytokines, including gamma interferon (IFN-gamma) and interleukin-12 (IL-12), are reduced but secretion of the anti-inflammatory cytokine IL-10 is increased in response to a subsequent LPS challenge. This pattern of cytokine production is also characteristic of postinflammatory immunosuppression. Therefore, we hypothesized that LPS-primed mice would exhibit an impaired ability to respond to systemic infection with the opportunistic pathogen Pseudomonas aeruginosa. We further hypothesized that depletion of IL-10 would reverse the endotoxin-tolerant state. To test this hypothesis, systemic clearance of Pseudomonas aeruginosa was measured for LPS-primed wild-type and IL-10-deficient mice. LPS-primed wild-type mice exhibited significant suppression of LPS-induced IFN-gamma and IL-12 but increased IL-10 production in blood and spleen compared to levels exhibited by saline-primed wild-type mice. The suppressed production of IFN-gamma and IL-12 caused by LPS priming was ablated in the spleens, but not blood, of IL-10 knockout mice. LPS-primed wild-type mice cleared Pseudomonas aeruginosa from lungs and blood more effectively than saline-primed mice. LPS-primed IL-10-deficient mice were particularly efficient in clearing Pseudomonas aeruginosa after systemic challenge. These studies show that induction of LPS tolerance enhanced systemic clearance of Pseudomonas aeruginosa and that this effect was augmented by neutralization of IL-10.
Asunto(s)
Interleucina-10/deficiencia , Interleucina-10/metabolismo , Lipopolisacáridos/farmacología , Pseudomonas aeruginosa/inmunología , Animales , Biomarcadores , Regulación de la Expresión Génica , Tolerancia Inmunológica/efectos de los fármacos , Tolerancia Inmunológica/inmunología , Interferón gamma/biosíntesis , Interferón gamma/sangre , Interferón gamma/genética , Interleucina-10/sangre , Interleucina-10/genética , Interleucina-12/biosíntesis , Interleucina-12/sangre , Interleucina-12/genética , Lipopolisacáridos/inmunología , Pulmón/microbiología , Ratones , Ratones Noqueados , ARN Mensajero/biosíntesis , ARN Mensajero/genética , Cloruro de Sodio/farmacologíaRESUMEN
Aging is accompanied by an altered stress response that underlies increased susceptibility of the elderly patients to physiological stress such as infection and sepsis. In the present study, we investigated the effects of aging on mortality, hypothermia, and cytokine induction in mouse models of intra-abdominal sepsis and endotoxemia. Systemic inflammation associated with either cecal ligation/puncture (CLP) or injection with bacterial endotoxin, lipopolysaccharide (LPS), resulted in a significantly elevated mortality rate in aged (24 months) compared to young (4 months) mice. The aged mice also showed profound hypothermia during these inflammatory stresses; the severity of hypothermia at the early phase of sepsis or endotoxemia could predict the mortality of individual animals. The stress-mediated induction of interleukin-1beta, interleukin-6, and interleukin-10 (IL-1beta, IL-6, and IL-10) in the circulating blood tended to be higher with aging in both CLP and LPS models, and in particular, the induction of IL-6 was significantly augmented with aging. The serum level of IL-6 showed a strong correlation with degrees of hypothermia. In the heart and lungs, the induction of mRNA for IL-6 and IL-10 was also significantly enhanced with aging. These results clearly demonstrate an age-associated increase in mortality, hypothermia, and induction of IL-6 during endotoxemia and sepsis.
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Envejecimiento , Citocinas/biosíntesis , Endotoxemia/complicaciones , Endotoxemia/mortalidad , Hipotermia/complicaciones , Sepsis/complicaciones , Sepsis/mortalidad , Animales , Proteína beta Potenciadora de Unión a CCAAT/metabolismo , Citocinas/sangre , Citocinas/genética , Endotoxemia/metabolismo , Regulación de la Expresión Génica , Corazón/fisiopatología , Hipotermia/sangre , Interleucina-1/biosíntesis , Interleucina-10/biosíntesis , Interleucina-6/biosíntesis , Pulmón/metabolismo , Pulmón/fisiopatología , Masculino , Ratones , Ratones Endogámicos C57BL , Miocardio/metabolismo , FN-kappa B/metabolismo , Sepsis/metabolismoRESUMEN
A monomeric model for murine antiapoptotic protein Bcl-2 was constructed by comparative modeling with the software suite MPACK (EXDIS/DIAMOD/FANTOM) using human Bcl-xL as a template. The monomeric model shows that murine Bcl-2 is an all alpha-helical protein with a central (helix 5) hydrophobic helix surrounded by amphipathic helices and an unstructured loop of 30 residues connecting helices 1 and 2. It has been previously shown that phosphorylation of Ser 70 located in this loop region regulates the anti-apoptotic activity of Bcl-2. Based on our current model, we propose that this phosphorylation may result in a conformational change that aids multimer formation. We constructed a model for the Bcl-2 homodimer based on the experimentally determined 3D structure of the Bcl-xL: Bad peptide complex. The model shows that it will require approximately a half turn in helix 2 to expose hydrophobic residues important for the formation of a multimer. Helices 5 and 6 of the monomeric subunit Bcl-2 have been proposed to form an ion-channel by associating with helices 5 and 6 of another monomeric subunit in the higher-order complex. In the multimeric model of Bcl-2, helices 5 and 6 of each subunit were placed distantly apart. From our model, we conclude that a global conformational change may be required to bring helices 5 and 6 together during ion-channel formation.
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Apoptosis , Procesamiento Proteico-Postraduccional , Proteínas Proto-Oncogénicas c-bcl-2/química , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Secuencia de Aminoácidos , Animales , Secuencia Conservada , Dimerización , Humanos , Interacciones Hidrofóbicas e Hidrofílicas , Ratones , Modelos Moleculares , Datos de Secuencia Molecular , Estructura Cuaternaria de Proteína , Estructura Terciaria de Proteína , Alineación de Secuencia , Homología Estructural de ProteínaRESUMEN
beta 2 microglobulin knockout (beta2M-/-) mice lack CD8+ T and natural killer T cells. We hypothesized that beta 2M-/- mice are resistant to lethal intraabdominal sepsis. To test this hypothesis, mortality, cytokine production, and physiologic function were assessed in beta 2M-/- mice during sepsis caused by cecal ligation and puncture (CLP). beta 2M-/- mice survived significantly longer than wild-type mice after CLP but ultimately exhibited 100% mortality. Treatment of beta 2M-/- mice with anti-asialoGM1 to deplete natural killer cells conferred greater than 70% long-term survival. Compared with wild-type mice, beta 2M-/- mice treated with anti-asialoGM1 produced decreased amounts of proinflammatory cytokines and did not exhibit hypothermia or metabolic acidosis after CLP. Adoptive transfer of CD8+ T and natural killer cells into beta 2M-/- mice treated with anti-asialoGM1 re-established CLP-induced mortality. CD8 knockout mice treated with anti-asialoGM1, which are specifically deficient in CD8+ T and natural killer cells, exhibited 40% long-term survival after CLP. Furthermore, treatment of wild-type mice with antibodies to CD8 and asialoGM1 conferred a significant survival benefit compared with wild-type mice treated with nonspecific IgG. These findings demonstrate that beta 2M-/- mice treated with anti-asialoGM1 are resistant to CLP-induced mortality and that depletion of CD8+ T and natural killer cells largely accounts for the survival benefit observed in these mice.
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Linfocitos T CD8-positivos/inmunología , Modelos Animales de Enfermedad , Inmunidad Innata/inmunología , Células Asesinas Naturales/inmunología , Linfopenia/inmunología , Ratones Noqueados , Ratones Noqueados/inmunología , Peritonitis/inmunología , Sepsis/inmunología , Microglobulina beta-2 , Traslado Adoptivo , Animales , Ciego/lesiones , Ciego/cirugía , Femenino , Gangliósido G(M1)/antagonistas & inhibidores , Inmunidad Innata/genética , Inflamación , Ligadura , Linfopenia/etiología , Linfopenia/mortalidad , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados/genética , Peritonitis/etiología , Peritonitis/mortalidad , Sepsis/etiología , Sepsis/mortalidad , Análisis de Supervivencia , Microglobulina beta-2/genéticaRESUMEN
Although aldose reductase (AR) is a critical participant in osmoregulation, and the metabolism of glucose and aldehydes derived from lipid peroxidation, post-translational mechanisms regulating its activity have not been identified. In this paper, we report that stimulation of protein kinase C (PKC) in several cell types induces phosphorylation of AR and translocation of the phosphorylated protein to the mitochondria. In vitro, recombinant AR was directly phosphorylated by activated PKC, suggesting that AR may be an in vivo PKC substrate. Together, these observations reveal a novel link between PKC activation and the regulation of glucose and aldehyde metabolism.
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Aldehído Reductasa/metabolismo , Mitocondrias/metabolismo , Proteína Quinasa C/metabolismo , Aldehído Reductasa/genética , Animales , Brioestatinas , Células COS , Células Cultivadas , Células HL-60 , Humanos , Membranas Intracelulares/metabolismo , Lactonas/farmacología , Macrólidos , Mitocondrias/efectos de los fármacos , Músculo Liso Vascular/citología , Radioisótopos de Fósforo , Fosforilación , Proteína Quinasa C/efectos de los fármacos , Transporte de Proteínas , Ratas , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Especificidad por Sustrato , Acetato de Tetradecanoilforbol/farmacologíaRESUMEN
Thermal injury to 40% or more of the total body surface area poses a significant risk for the development of opportunistic infections that increase complications and mortality. Altered cytokine induction profiles, including suppression of the Th1 cytokines IFN-gamma and IL-12 and elevations in the anti-inflammatory cytokine IL-10, are believed to contribute to burn-associated immunosuppression and the development of sepsis. The specific changes that lead to altered cytokine production following major burns are not known. We examined the effects of burn injuries to 40% of the mouse body surface on IFN-gamma induction in the major IFN-gamma-producing cell types of the spleen. Additionally, effects on key IFN-gamma-regulatory cytokines were examined after bacterial challenge. We report that in vivo induction of IFN-gamma in natural killer lymphocytes is suppressed in burned mice. Splenic IFN-gamma was suppressed at both the mRNA and protein levels. Early suppression was associated with impairments in both the macrophage/dendritic cell and lymphocyte populations, whereas persistent suppression was associated with impaired lymphocyte function and decreased responsiveness to IFN-gamma-inducing factors. IFN-gamma production could be restored by neutralization of the upregulated cytokine IL-10. Induction of the IFN-gamma-inducers IL-15, IL-12, and IL-2 was also impaired after burn injury, whereas IL-18 levels remained unaffected. Exogenous application of these suppressed cytokines to isolated splenocytes did not restore IFN-gamma to sham levels, indicating a loss of responsiveness to these factors. Expression of the IL-2, IL-12, and IL-15 receptors was suppressed after thermal injury. We conclude that burn-associated suppression of IFN-gamma is due to deficient production of inducing factors and their receptors, leading to severe impairments in cellular IFN-gamma induction pathways.
Asunto(s)
Quemaduras/metabolismo , Citocinas/biosíntesis , Interferón gamma/biosíntesis , Linfocitos/metabolismo , Receptores de Citocinas/metabolismo , Animales , Células Cultivadas , Técnicas de Cocultivo , Citocinas/genética , Femenino , Interleucina-10/metabolismo , Interleucina-12/metabolismo , Células Asesinas Naturales/metabolismo , Macrófagos/metabolismo , Ratones , Ratones Endogámicos BALB C , Pseudomonas aeruginosa/patogenicidad , Bazo/citología , Bazo/metabolismoRESUMEN
Gamma interferon (IFN-gamma) is an important mediator of endotoxin (lipopolysaccharide [LPS])-induced immune responses. However, the specific cell types that produce IFN-gamma in response to LPS and the cellular factors that regulate LPS-induced IFN-gamma production have not been fully determined. The present studies were undertaken to characterize the cell populations that produce IFN-gamma after LPS challenge in the spleens of mice and to determine the regulatory factors that modulate LPS-induced production of IFN-gamma. Our studies show that the levels of splenic IFN-gamma mRNA and protein production peak at 6 and 8 h, respectively, after systemic LPS challenge. Approximately 60% of IFN-gamma-producing cells are natural killer (NK) cells (CD3(-)DX5(+)) and 25% are NKT cells (CD3(+)DX5(+)). Most of the remaining IFN-gamma-producing cells are T cells (CD3(+)DX5(-)), macrophages, and dendritic cells. Functionally, interleukin-12 (IL-12) is the major IFN-gamma-stimulating factor after LPS challenge, with costimulation provided by IL-15, IL-18, and B7 proteins. IL-10 is a major inhibitor of LPS-induced IFN-gamma production. Unlike intact heat-killed gram-negative and gram-positive bacteria, the class II major histocompatibility complex did not play a functional role in LPS-induced IFN-gamma production. LPS is a potent stimulus for splenic IL-10, IL-12 p40, and IL-15 mRNA expression, whereas IL-12 p35 and IL-18 mRNAs, as well as B7 proteins, are constitutively expressed in the mouse spleen. Of the factors studied, IL-18 serves as the most potent costimulus with IL-12 for IFN-gamma production, followed by IL-15 and B7 proteins. These data demonstrate that NK cells and NKT cells are the most abundant IFN-gamma-producing cells in the mouse spleen after LPS challenge and that IL-10 and IL-12 are key functional regulators of LPS-induced IFN-gamma production.