Human rhinovirus-induced inflammatory responses are inhibited by phosphatidylserine containing liposomes.

Human rhinovirus (HRV) infections are major contributors to the healthcare burden associated with acute exacerbations of chronic airway disease, such as chronic obstructive pulmonary disease and asthma. Cellular responses to HRV are mediated through pattern recognition receptors that may in part signal from membrane microdomains. We previously found Toll-like receptor signaling is reduced, by targeting membrane microdomains with a specific liposomal phosphatidylserine species, 1-stearoyl-2-arachidonoyl-sn-glycero-3-phospho-L-serine (SAPS). Here we explored the ability of this approach to target a clinically important pathogen. We determined the biochemical and biophysical properties and stability of SAPS liposomes and studied their ability to modulate rhinovirus-induced inflammation, measured by cytokine production, and rhinovirus replication in both immortalized and normal primary bronchial epithelial cells. SAPS liposomes rapidly partitioned throughout the plasma membrane and internal cellular membranes of epithelial cells. Uptake of liposomes did not cause cell death, but was associated with markedly reduced inflammatory responses to rhinovirus, at the expense of only modest non-significant increases in viral replication, and without impairment of interferon receptor signaling. Thus using liposomes of phosphatidylserine to target membrane microdomains is a feasible mechanism for modulating rhinovirus-induced signaling, and potentially a prototypic new therapy for viral-mediated inflammation.

Rhinoviral infection and asthma: the detection and management of rhinoviruses by airway epithelial cells.

Human rhinoviruses (HRV) have been linked to the development of childhood asthma and recurrent acute asthma exacerbations throughout life, and contribute considerably to the healthcare and economic burden of this disease. However, the ability of HRV infections to trigger exacerbations, and the link between allergic status and HRV responsiveness, remains incompletely understood. Whilst the receptors on human airway cells that detect and are utilized by most HRV group A and B, but not C serotypes are known, how endosomal pattern recognition receptors (PRRs) detect HRV replication products that are generated within the cytoplasm remains somewhat of an enigma. In this article, we explore a role for autophagy, a cellular homeostatic process that allows the cell to encapsulate its own cytosolic constituents, as the crucial mechanism controlling this process and regulating the innate immune response of airway epithelial cells to viral infection. We will also briefly describe some of the recent insights into the immune responses of the airway to HRV, focusing on neutrophilic inflammation that is a potentially unwanted feature of the acute response to viral infection, and the roles of IL-1 and Pellinos in the regulation of responses to HRV.

Muckle-Wells syndrome without mutation in exon 3 of the NLRP3 gene, identified by evidence of excessive monocyte production of functional interleukin 1ß and rapid response to anakinra.

We report a man with lifelong urticaria, night sweats, arthralgia and lethargy. He had high levels of inflammatory markers and serum amyloid A, but no identifiable mutation in exon 3 of the NLRP3 (NOD-like receptor family, pyrin domain-1 containing 3) gene, and no relevant family history. We found marked production of functional interleukin (IL)-1 by the patient's monocytes at baseline and after stimulation with lipopolysaccharide. The patient made an immediate response to treatment with an IL-1ß receptor antagonist. We propose that this patient has Muckle-Wells syndrome without deafness, occurring de novo. Functional screening for IL-1 production could aid diagnosis in future similar cases.

Diesel exhaust particles override natural injury-limiting pathways in the lung.

Induction of effective inflammation in the lung in response to environmental and microbial stimuli is dependent on cooperative signaling between leukocytes and lung tissue cells. We explored how these inflammatory networks are modulated by diesel exhaust particles (DEP) using cocultures of human monocytes with epithelial cells. Cocultures, or monoculture controls, were treated with DEP in the presence or absence of LPS or flagellin. Production of cytokines was explored by Western blotting and ELISA; cell signaling was analyzed by Western blotting. Here, we show that responses of epithelial cells to DEP are amplified by the presence of monocytes. DEP amplified the responses of cellular cocultures to very low doses of TLR agonists. In addition, in the presence of DEP, the responses induced by LPS or flagellin were less amenable to antagonism by the physiological IL-1 antagonist, IL-1ra. This was paralleled by the uncoupling of IL-1 production and release from monocytes, potentially attributable to an ability of DEP to sequester or degrade extracellular ATP. These data describe a model of inflammation where DEP amplifies responses to low concentrations of microbial agonists and alters the nature of the inflammatory milieu induced by TLR agonists.

Pathological networking: a new approach to understanding COPD.

Developing new treatments for chronic obstructive pulmonary disease (COPD) is extremely challenging. This disease, chronic by definition, becomes apparent only after substantial--and probably irreversible--tissue damage has occurred. The observable phenotype is of a stable disease state whose progression is hard to influence and reversal of which appears almost impossible. Identifying key components of the pathological process, targeting of which will result in substantial clinical benefit, is a significant challenge. In this review the nature of the disease is examined and conceptual information and simple tissue models of inflammation are used to explore the pathological network that is COPD. From the concept of COPD as a disease network displaying the features of contiguous immunity (in which many processes of innate and adaptive immunity are in continual dialogue and evolution), refinements are suggested to the strategies aimed at developing effective new treatments for this disease.

The role of TLR activation in inflammation.

The Toll-like receptor family was originally identified in Drosophila, where it provides important developmental and immunological signalling. In mammals, the developmental signal appears to have been lost, but the immunological defence role of these receptors has been expanded to provide broad recognition of bacterial, fungal, viral and parasitic pathogens. There is increasing evidence that these receptors go beyond the recognition of microbial molecules to sense host tissue damage. Recognition of host molecules and commensal microbes is also involved in the restoration of normal tissue architecture after injury and in maintenance of epithelial health. Recent developments in the TLR field highlight the importance of these molecules to human health and disease and demonstrate that their targeting, to boost immunity or inhibit inflammation, is both feasible and also potentially challenging.

Translational mini-review series on Toll-like receptors: networks regulated by Toll-like receptors mediate innate and adaptive immunity.

The Toll-like receptor (TLR) family provide key components of mammalian immunity and are part of the earliest surveillance mechanisms responding to infection. Their activation triggers the innate immune response, and is crucial to the successful induction of Th1/Th2-phenotyped adaptive immunity. Innate immunity was long considered to be non-specific and somewhat simple compared to adaptive immunity, mediated via the engulfment and lysis of microbial pathogens by phagocytic cells such as macrophages and neutrophils, and involving no complex protein-protein interactions. The emergence of the TLR field has contributed to a revision of our understanding, and innate immunity is now viewed as a highly complex process, in line with adaptive immunity. This review will give a brief overview of our current knowledge of TLR biology, and will focus on TLRs as key components in complex networks that activate, integrate and select the appropriate innate and adaptive immune responses in the face of immunological danger.

Toll-like receptors: their role in allergy and non-allergic inflammatory disease.

The human TLRs comprise an important and interesting group of receptors that regulate pathogen-related responses, and play as yet uncharacterized roles in the amplication of sterile inflammation. Signalling through these receptors, which are powerfully coupled in gene transcription processes, has powerful immunostimulatory and immunomodulatory effects. Exploitation of TLR signalling will probably lead to novel effective therapies for allergic disease, in the first instance through more efficient mechanisms of immunotherapy. The likelihood of adverse consequences of such treatments, though possible, may be minimized by use of conjugated vaccines.

IL-1beta induced changes in hypothalamic IL-1R1 and IL-1R2 mRNA expression in the rat.

Interleukin-1 receptor (IL-1R1 and IL-1R2) mRNA expression was detected within the rat hypothalamus, a primary site of IL-1 action, using RT-PCR. Levels of expression were unchanged by cardiac saline-perfusion. However, intracerebroventricular (i.c.v.) administration of IL-1beta caused changes in receptor mRNA expression in non-perfused animals that were profoundly different to those observed in their saline-perfused counterparts. This study demonstrates the importance of perfusing tissue to remove blood cells when determining changes in IL-1 receptor mRNA expression.

Cortical cell death induced by IL-1 is mediated via actions in the hypothalamus of the rat.

The cytokine IL-1 mediates diverse forms of neurodegeneration, but its mechanism of action is unknown. We have demonstrated previously that exogenous and endogenous IL-1 acts specifically in the rat striatum to dramatically enhance ischemic and excitotoxic brain damage and cause extensive cortical injury. Here we tested the hypothesis that this distant effect of IL-1 is mediated through polysynaptic striatal outputs to the cortex via the hypothalamus. We show that IL-1beta injected into the rat striatum with the excitotoxin alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (S-AMPA) caused increased expression of IL-1beta (mRNA and protein) mainly in the cortex where maximum injury occurs. Marked increases in IL-1beta mRNA and protein were also observed in the hypothalamus. S-AMPA, injected alone into the striatum, caused only localized damage, but administration of IL-1beta into either the striatum or the lateral hypothalamus immediately after striatal S-AMPA resulted in widespread cell loss throughout the ipsilateral cortex. Finally we showed that the cortical cell death produced by striatal coinjection of S-AMPA and IL-1beta was significantly reduced by administration of the IL-1 receptor antagonist into the lateral hypothalamus. These data suggest that IL-1beta can act in the hypothalamus to modify cell viability in the cortex. We conclude that IL-1-dependent pathways project from the striatum to the cortex via the hypothalamus and lead to cortical injury, and that these may contribute to a number of human neurological conditions including stroke and head trauma.