Pneumococcal infections remain a leading cause of death in persons ≥ 65 y of age. Recent reports have illustrated detrimental changes in the endoplasmic reticulum stress response or unfolded protein response in aging and age-related diseases; however, the relationship between aging, the unfolded protein response, and innate immune responses to Streptococcus pneumoniae has not been fully elucidated. Our results illustrate that stimulator of IFN genes-mediated production of IFN-β during S. pneumoniae infection is decreased in aged hosts. Enhanced endoplasmic reticulum stress in response to S. pneumoniae augmented inositol-requiring protein 1/X-box binding protein 1-mediated production of autophagy-related gene 9 (Atg9a). Knockdown of Atg9a or treatment with gemcitabine HCl resulted in enhanced stimulator of IFN genes-mediated production of IFN-β by aged macrophages. Consecutive treatments with gemcitabine during in vivo S. pneumoniae infection decreased morbidity and mortality in aged hosts, which was associated with decreased Atg9a expression, increased IFN-β production, and improved bacterial clearance from lung tissue. Taken together, data presented in this study provide new evidence as to why older persons are more susceptible to S. pneumoniae, and provide a possible mechanism to enhance these responses, thereby decreasing morbidity and mortality in this population.
Abstract Objective To determine functional responses of neonatal chicken and turkey heterophils to various inflammatory agonists. Animals 100 one-day-old chickens and turkeys. Procedure Blood heterophils were isolated and stimulated for 30 minutes at 39 C with ionomycin, phorbol myristate acetate (PMA), opsonized zymosan (OZ), or formyl-methionyl-leucyl-phenylalanine (FMLP). Functional responses (shape change, adherence, phagocytosis, influx of intracellular calcium, and oxidative burst) of stimulated heterophils were measured and compared with responses of unstimulated (control) heterophils. Results Turkey and chicken heterophils did not respond to FMLP stimulation. Stimulation of chicken and turkey heterophils with ionomycin resulted in significant increases in adherence, percentage of cells with a shape change, phagocytosis, intracellular calcium concentration, and oxidative burst. Turkey heterophils did not respond to PMA stimulation, whereas stimulation of chicken heterophils with PMA resulted in significant increases in adherence, percentage of cells with a shape change, phagocytosis, and oxidative burst but not intracellular calcium concentration. Stimulation of chicken and turkey heterophils with OZ resulted in significant increases in oxidative burst. Conclusions Mechanisms regulating initiation of heterophil activation in neonatal chicken and turkey heterophils are consistent with those described for heterophils isolated from mature birds. The biochemical and cytoskeletal systems of neonatal avian heterophils undergo functional alterations following stimulation with inflammatory agonists. Clinical Relevance Understanding heterophil activation and regulation should eventually lead to methods for controlling bacterial diseases in poultry. ( Am J Vet Res 1998;59:1404–1408)
Unmethylated CpG oligodinucleotides (CpG-ODN) flanked by specific bases found in bacterial DNA are known to stimulate innate immune responses. In this study, synthetic CpG-ODNs were evaluated for their in vitro stimulation of leukocyte and in vivo protection against Salmonella enteritidis (SE) in neonatal chickens. Our studies showed that CpG-ODN stimulated bactericidal activities, releasing granules (degranulation) and generating reactive oxygen species (oxidative burst), in chicken heterophils and up regulated nitric oxide production in chicken peripheral blood monocytes. When day-old chickens were given (i.p.) synthetic CpG-ODNs followed by oral challenge of SE, a significant reduction (p<0.05) of organ invasion by SE was observed in chickens pretreated with CpG-ODN containing the immunostimulatory GTCGTT motif. This CpG-OND also significantly reduced mortality of chickens with acute peritoneal infection of SE. Our study provides evidence that immunostimulatory CpG-ODN stimulated innate immune activities and enhanced the resistance to infectious pathogens in neonatal chickens.
An epidemic of Severe Acute Respiratory Syndrome (SARS) led to the identification of an associated coronavirus, SARS-CoV. This virus evades the host innate immune response in part through the expression of its non-structural protein (nsp) 1, which inhibits both host gene expression and virus- and interferon (IFN)-dependent signaling. Thus, nsp1 is a promising target for drugs, as inhibition of nsp1 would make SARS-CoV more susceptible to the host antiviral defenses. To gain a better understanding of nsp1 mode of action, we generated and analyzed 38 mutants of the SARS-CoV nsp1, targeting 62 solvent exposed residues out of the 180 amino acid protein. From this work, we identified six classes of mutants that abolished, attenuated or increased nsp1 inhibition of host gene expression and/or antiviral signaling. Each class of mutants clustered on SARS-CoV nsp1 surface and suggested nsp1 interacts with distinct host factors to exert its inhibitory activities. Identification of the nsp1 residues critical for its activities and the pathways involved in these activities should help in the design of drugs targeting nsp1. Significantly, several point mutants increased the inhibitory activity of nsp1, suggesting that coronaviruses could evolve a greater ability to evade the host response through mutations of such residues.
Heterophils, the functional equivalent to the mammalian neutrophil, are important mediators of natural resistance against invasive pathogens in poultry. Young poultry are susceptible to pathogens, such as Salmonella enteritidis, during the first week post-hatch. No studies have evaluated the ontogeny of heterophil function in turkeys during the first few weeks post-hatch. Previous studies from our laboratory have shown day-old poults were protected against S. enteritidis organ invasion following immunoprophylactic administration of chicken S. enteritids immune lymphokines. Therefore, the objective in the present study was to characterize the development of phagocytosis and bacterial killing by turkey heterophils during the first 3 weeks of life and to compare the effect of immune lymphokines on the development of heterophil phagocytosis and killing during the first 3 weeks post-hatch. Both functional phagocytosis and killing activities were age-dependent events. During the first 1–7 days post-hatch, little functional activity was demonstrated which apparently is associated with susceptibility. Optimal heterophil phagocytosis and killing activities were reached 14–21 days post-hatch. Administrating immune lymphokines significantly potentiated phagocytosis (P < 0.01) and killing (P < 0.001) by turkey heterophils. In fact, immune lymphokine administration to 1–7-day-old poults augmented phagocytosis and killing activities of heterophils equivalent to levels found in functionally mature 14–21-day-old poults. These results demonstrate the ontogeny of the functional activity of the turkey heterophil is an age-related phenomenon, with inefficient phagocytosis and killing during the first week post-hatch. Prophylactic administration of immune lymphokines significantly potentiated the functional activity of the heterophil from poults during the first 3 weeks of life. Most importantly the administration of immune lymphokines enhanced the functional activity of heterophils from 1–7-day-old poults to levels comparable to that of an immunologically mature bird.
Neutrophil oxidative burst/degranulation activities were measured using CpG in vitro stimulation. Neutrophils isolated from pigs 6 weeks of age were incubated with treatment for 1 hr at 39°C.
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