Hydroxylases regulate intestinal fibrosis through the suppression of ERK mediated TGF-β1 signaling

Fibrosis is a complication of chronic inflammatory disorders such as inflammatory bowel disease (IBD), a condition which has limited therapeutic options and often requires surgical intervention. Pharmacologic inhibition of oxygen-sensing prolyl hydroxylases (PHD), which confer oxygen-sensitivity upon the hypoxia inducible factor (HIF) pathway, has recently been shown to have therapeutic potential in colitis, although the mechanisms involved remain unclear. Here, we investigated the impact of hydroxylase inhibition on inflammation-driven fibrosis in a murine colitis model. Mice exposed to dextran sodium sulfate followed by period of recovery developed intestinal fibrosis characterized by alterations in the pattern of collagen deposition and infiltration of activated fibroblasts. Treatment with the hydroxylase inhibitor dimethyloxalylglycine (DMOG) ameliorated fibrosis. TGF-β1 is a key regulator of fibrosis which acts through the activation of fibroblasts. Hydroxylase inhibition reduced TGF-β1-induced expression of fibrotic markers in cultured fibroblasts suggesting a direct role for hydroxylases in TGF-β1 signalling. This was at least in part due to inhibition of non-canonical activation of extracellular signal-regulated kinase (ERK) signalling. In summary, pharmacologic hydroxylase inhibition ameliorates intestinal fibrosis, through suppression of TGF-β1-dependent ERK activation in fibroblasts. We hypothesize that in addition to previously reported immunosupressive effects, hydroxylase inhibitors independently suppress pro-fibrotic pathways

Influence of Egr-1 in cardiac tissue-derived mesenchymal stem cells in response to glucose variations

Mesenchymal stem cells (MSCs) represent a promising cell population for cell therapy and regenerative medicine applications. However, how variations in glucose are perceived by MSC pool is still unclear. Since, glucose metabolism is cell type and tissue dependent, this must be considered when MSCs are derived from alternative sources such as the heart. The zinc finger transcription factor Egr-1 is an important early response gene, likely to play a key role in the glucose-induced response. Our aim was to investigate how short-term changes in in vitro glucose concentrations affect multipotent cardiac tissue-derived MSCs (cMSCs) in a mouse model of Egr-1 KO (Egr-1-/-). Results showed that loss of Egr-1 does not significantly influence cMSC proliferation. In contrast, responses to glucose variations were observed in wt but not in Egr-1 -/- cMSCs by clonogenic assay. Phenotype analysis by RT-PCR showed that cMSCs Egr-1-/- lost the ability to regulate the glucose transporters GLUT-1 and GLUT-4 and, as expected, the Egr-1 target genes VEGF, TGFβ-1, and p300. Acetylated protein levels of H3 histone were impaired in Egr-1-/- compared to wt cMSCs. We propose that Egr-1 acts as immediate glucose biological sensor in cMSCs after a short period of stimuli, likely inducing epigenetic modifications. © 2014 Daniela Bastianelli et al.

Do changes in transglutaminase activity alter latent transforming growth factor beta activation in experimental diabetic nephropathy?

Background. Diabetic nephropathy is the leading cause of end-stage kidney failure worldwide. It is characterized by excessive extracellular matrix accumulation. Transforming growth factor beta 1 (TGF-ß1) is a fibrogenic cytokine playing a major role in the healing process and scarring by regulating extracellular matrix turnover, cell proliferation and epithelial mesanchymal transdifferentiation. Newly synthesized TGF-ß is released as a latent, biologically inactive complex. The cross-linking of the large latent TGF-ß to the extracellular matrix by transglutaminase 2 (TG2) is one of the key mechanisms of recruitment and activation of this cytokine. TG2 is an enzyme catalyzing an acyl transfer reaction leading to the formation of a stable e(?-glutamyl)-lysine cross-link between peptides.Methods. To investigate if changes in TG activity can modulate TGF-ß1 activation, we used the mink lung cell bioassay to assess TGF-ß activity in the streptozotocin model of diabetic nephropathy treated with TG inhibitor NTU281 and in TG2 overexpressing opossum kidney (OK) proximal tubular epithelial cells.Results. Application of the site-directed TG inhibitor NTU281 caused a 25% reduction in kidney levels of active TGF-ß1. Specific upregulation of TG2 in OK proximal tubular epithelial cells increased latent TGF-ß recruitment and activation by 20.7% and 19.7%, respectively, in co-cultures with latent TGF-ß binding protein producing fibroblasts.Conclusions. Regulation of TG2 directly influences the level of active TGF-ß1, and thus, TG inhibition may exert a renoprotective effect by targeting not only a direct extracellular matrix deposition but also TGF-ß1 activation and recruitment.

Transglutaminase inhibition reduces fibrosis and preserves function in experimental chronic kidney disease

Progressive tissue fibrosis is involved in debilitating diseases that affect organs including the lungs, liver, heart, skin, and kidneys. Recent evidence suggests that tissue transglutaminase, an enzyme that crosslinks proteins, may be involved in tissue fibrosis by crosslinking and stabilizing the extracellular matrix or by recruiting and activating the large latent transforming growth factor (TGF)-β1 complex. We treated rats that had undergone 5/6-nephrectomy with two different irreversible inhibitors of transglutaminase and found that both prevented a decline in kidney function and reduced the development of glomerulosclerosis and tubulointerstitial fibrosis by up to 77% and 92%, respectively. Treatment reduced the accumulation of collagen I and collagen III, with the primary mechanism of action being direct interference with the crosslinking of extracellular matrix rather than altered regulation of TGFβ1. We conclude that inhibition of transglutaminase offers a potential therapeutic option for chronic kidney disease and other conditions that result from tissue fibrosis. Copyright © 2007 by the American Society of Nephrology.

Tissue transglutaminase and the progression of human renal scarring

ABSTRACT. Experimental renal scarring indicates that tissue transglutaminase (tTg) may be associated with the accumulation of extracellular matrix (ECM), both indirectly via TGF-β1 activation and directly by the formation of ε(γ-glutamyl) lysine dipeptide bonds within the ECM. The latter potentially accelerates deposition and confers the ECM with resistance to proteolytic digestion. Studied were 136 human renal biopsy samples from a range of chronic renal diseases (CRD) to determine changes in tTg and ε(γ-glutamyl) lysine crosslinking. Immunofluorescence for insoluble tTg showed a 14-fold increase in the kidneys of CRD patients (5.3 ± 0.5 versus 76 ± 54 mV/cm2), which was shown to be active by a similar 11-fold increase in the ε(γ-glutamyl) lysine crosslink (1.8 ± 0.2 versus 19.3 ± 14.2 mV/cm2). Correlations were obtained with renal function for tTg and crosslink. In situ hybridization for tTg mRNA showed that tubular epithelial cells were the major source of tTg; however, both mesangial and interstitial cells also contributed to elevated levels in CRD. This mRNA pattern was consistent with immunohistochemistry for soluble tTg. Changes in renal tTg and its product, the ε(γ-glutamyl) lysine crosslink, occur in progressive renal scarring in humans independently of the original etiology and in a similar manner to experimental models. tTg may therefore play a role in the pathogenesis of renal scarring and fibrosis in patients with CRD and can therefore be considered a potential therapeutic target. E-mail: T.Johnson@sheffield.ac.uk

Understanding the link between transglutaminase and the induction of fibrosis in cystic fibrosis (CF)

The emerging role of the multifunctional enzyme, Transglutaminase 2 (TG2) in Cystic Fibrosis (CF) has been linked to its increased expression and intracellular transamidating activity. However, a full understanding of the molecular mechanisms involved still remains unclear despite numerous studies that have attempted to delineate this process. These mechanisms include the NFκB and TGFβ1 pathway amongst others. This study reveals for the first time that the development of fibrosis in CF is due to a TG2-driven epithelial to mesenchymal transition (EMT) via a mechanism involving the activation of the pro-fibrotic cytokine TGFβ1. Using a human ΔF508/W1282X CFTR CF mutant bronchial cell (IB3-1), its CFTR corrected “add-back” cell (C38) as well as a primary human bronchial epithelial cell (HBEC), elevated TG2 levels in the CFTR mutant IB3 cell were shown to activate latent TGFβ1 leading to increased levels found in the culture medium. This activation process was blocked by the presence of cell-permeable and impermeable TG2 inhibitors while inhibition of TGFβ1 receptors blocked TG2 expression. This demonstrates the direct link between TG2 and TGFβ1 in CF. The presence of active cell surface TG2 correlated with an increase in the expression of EMT markers, associated with the CF mutant cells, which could be blocked by the presence of TG2 inhibitors. This was mimicked using the “addback” C38 cell and the primary human bronchial epithelial cell, HBEC, where an increase in TG2 expression and activity in the presence of TGFβ1 concurred with a change in cell morphology and an elevation in EMT marker expression. Conversely, a knockdown of TG2 in the CF mutant IB3 cells illustrated that an inhibition of TG2 blocks the increase in EMT marker expression as well as causing an increase in TEER measurement. This together with an increase in the migration profile of the CF mutant IB3 cell against the “add-back” C38 cell suggests that TG2 drives a mesenchymal phenotype in CF. The involvement of TG2 activated TGFβ1 in CF was further demonstrated with an elevation/inhibition of p- SMAD 2 and 3 activation in the presence of TGFβ1/TG2 cell-permeable/impermeable inhibitors respectively. The use of a comparative airway cell model where bronchial epithelial cells were cultured at the air liquid interface (ALI) confirmed the observations in submerged culture depicting the robustness of the model and reiterated the importance of TG2 in CF. Using a CFTR corrector combined with TG2 inhibitors, this study showed that the correction and stabilisation of the ΔF508 CFTR mutation in the mutant cell forged an increase in matured CFTR copies trafficking to the apical surface by circumventing proteosomal degradation. Thus the results presented here suggests that TG2 expression is elevated in the CFTR mutant bronchial cell via a TGFβ1 driven positive feedback cycle whereby activation of latent TGFβ1 by TG2 leads in turn to an elevation in its own expression by TGFβ1. This vicious cycle then drives EMT in CF ultimately leading to lung remodelling and fibrosis. Importantly, TG2 inhibition blocks TGFβ1 activation leading to an inhibition of EMT and further blocks the emerging fibrosis, thus stabilizing and supporting the maturation, trafficking and conductance of CFTR channels at the apical surface.

Age-associated changes in long-chain fatty acid profile during healthy aging promote pro-inflammatory monocyte polarization via PPARγ

Differences in lipid metabolism associate with age-related disease development and lifespan. Inflammation is a common link between metabolic dysregulation and aging. Saturated fatty acids (FAs) initiate pro-inflammatory signalling from many cells including monocytes; however, no existing studies have quantified age-associated changes in individual FAs in relation to inflammatory phenotype. Therefore, we have determined the plasma concentrations of distinct FAs by gas chromatography in 26 healthy younger individuals (age < 30 years) and 21 healthy FA individuals (age > 50 years). Linear mixed models were used to explore the association between circulating FAs, age and cytokines. We showed that plasma saturated, poly- and mono-unsaturated FAs increase with age. Circulating TNF-α and IL-6 concentrations increased with age, whereas IL-10 and TGF-β1 concentrations decreased. Oxidation of MitoSOX Red was higher in leucocytes from FA adults, and plasma oxidized glutathione concentrations were higher. There was significant colinearity between plasma saturated FAs, indicative of their metabolic relationships. Higher levels of the saturated FAs C18:0 and C24:0 were associated with lower TGF-β1 concentrations, and higher C16:0 were associated with higher TNF-α concentrations. We further examined effects of the aging FA profile on monocyte polarization and metabolism in THP1 monocytes. Monocytes preincubated with C16:0 increased secretion of pro-inflammatory cytokines in response to phorbol myristate acetate-induced differentiation through ceramide-dependent inhibition of PPARγ activity. Conversely, C18:1 primed a pro-resolving macrophage which was PPARγ dependent and ceramide dependent and which required oxidative phosphorylation. These data suggest that a midlife adult FA profile impairs the switch from proinflammatory to lower energy, requiring anti-inflammatory macrophages through metabolic reprogramming.

Age-associated changes in long-chain fatty acid profile during healthy aging promote pro-inflammatory monocyte polarization via PPARγ

Differences in lipid metabolism associate with age-related disease development and lifespan. Inflammation is a common link between metabolic dysregulation and aging. Saturated fatty acids (FAs) initiate pro-inflammatory signalling from many cells including monocytes; however, no existing studies have quantified age-associated changes in individual FAs in relation to inflammatory phenotype. Therefore, we have determined the plasma concentrations of distinct FAs by gas chromatography in 26 healthy younger individuals (age < 30 years) and 21 healthy FA individuals (age > 50 years). Linear mixed models were used to explore the association between circulating FAs, age and cytokines. We showed that plasma saturated, poly- and mono-unsaturated FAs increase with age. Circulating TNF-α and IL-6 concentrations increased with age, whereas IL-10 and TGF-β1 concentrations decreased. Oxidation of MitoSOX Red was higher in leucocytes from FA adults, and plasma oxidized glutathione concentrations were higher. There was significant colinearity between plasma saturated FAs, indicative of their metabolic relationships. Higher levels of the saturated FAs C18:0 and C24:0 were associated with lower TGF-β1 concentrations, and higher C16:0 were associated with higher TNF-α concentrations. We further examined effects of the aging FA profile on monocyte polarization and metabolism in THP1 monocytes. Monocytes preincubated with C16:0 increased secretion of pro-inflammatory cytokines in response to phorbol myristate acetate-induced differentiation through ceramide-dependent inhibition of PPARγ activity. Conversely, C18:1 primed a pro-resolving macrophage which was PPARγ dependent and ceramide dependent and which required oxidative phosphorylation. These data suggest that a midlife adult FA profile impairs the switch from proinflammatory to lower energy, requiring anti-inflammatory macrophages through metabolic reprogramming.

Importance of tissue transglutaminasenitrosylation in fibroblasts migration and MMPregulation

As an extracellular second messenger, nitric oxide (NO) mediates the modification of proteins through nitrosylation of cysteine andtyrosine residues. Tissue Transglutaminase (TG2) is a Ca2+ activated, sulfhydryl rich protein with 18 free cysteine residues, which catalyzes ε-(γ glutamyl)lysine crosslink between extracellular and intracellular proteins. NO can nitrosylate up to 15 of the cysteine residues in TG2, leading to the irreversible inactivation of the enzyme activity. The interplay between these two agents was revealed for the first time by our study showing that NO inhibited the TG2-induced transcriptional activation of TGFb1and extracellular matrix (ECM) protein synthesis by nitrosylating TG2 in an inactive confirmation with inert catalytic activity. However, nitrosylated TG2 was still able to serve as a novel cell adhesion protein. In the light of our previous findings, in this study we aim to elucidate the NO modified function of TG2 in cell migration using an in vitro model mimicking the tissue matrix remodeling phases of wound healing. Using transfected fibroblasts expressing TG2 under the control of the tetracycline-off promoter, we demonstrate that upregulation of TG2 expression and activity inhibited the cell migration through the activation of TGFβ1. Increased TG2 activity led to arise in the biosynthesis and activity of the gelatinases, MMP-2 andMMP-9, while decreasing the biosynthesis and activity of the col-lagenases MMP-1a and MMP-13. NO donor S-Nitroso-N-acetyl-penicillamine (SNAP) treatment relieved the TG2 obstructed-cellmigration by blocking the TG2 enzyme activity. In addition,decrease in TG2 activity due to nitrosylation led to an inhibition of TGFβ1, which in turn affected the pattern of MMP activation. Recent evidence suggests that, once in complex with fibronectin in the ECM, TG2 can interact with syndecan-4 or integrinβ-1and regulate the cell adhesion. In the other part of this study, the possible role of nitrosylated TG2 on the regulation of cell migration during wound healing was investigated with respect to its interactions with integrin β1 (ITGβ1) and syndecan-4 (SDC4). Treatment with TG2 inhibitor Z-DON resulted in a 50% decrease in the TG2 interaction with ITGB1 and SDC4, while increasing concentrations of SNAP firstly led to a substantial decrease and then completely abolished the TG2/ITGβ1 and TG2/SDC4 complex formation on the cell surface. Taken together, data obtained from this study suggests that nitrosylation of TG2 leads to a change not only in the binding partners of TG2 on cell surface but also in TGFβ1-dependent MMP activation, which give rise to an increase in the migration potential of fibroblasts.

A novel regulatory role for tissue transglutaminase in epithelial-mesenchymal transition in cystic fibrosis

Cystic fibrosis (CF) is a genetic disorder caused by mutation of the cystic fibrosis transmembrane conductance regulator (CFTR) for which there is no overall effective treatment. Recent work indicates tissue transglutaminase (TG2) plays a pivotal intracellular role in proteostasis in CF epithelia and that the pan TG inhibitor cysteamine improves CFTR stability. Here we show TG2 has another role in CF pathology linked with TGFβ1 activation and signalling, induction of epithelial-mesenchymal transition (EMT), CFTR stability and induction of matrix deposition. We show that increased TG2 expression in normal and CF bronchial epithelial cells increases TGFβ1 levels, promoting EMT progression, and impairs tight junctions as measured by Transepithelial Electric Resistance (TEER) which can be reversed by selective inhibition of TG2 with an observed increase in CFTR stability. Our data indicate that selective inhibition of TG2 provides a potential therapeutic avenue for reducing fibrosis and increasing CFTR stability in CF.

TG2: a credible therapeutic target in fibrotic diseasedue to its multifunctional roles

The role of TG2 in fibrosis is reported to be related to two important effects. The first in mediating the deposition and accumulation of the fibrotic extracellular matrix (ECM) via its cross-linking of proteins like fibronectin, collagen I and collagen III; and the second, the activation of latent matrix bound TGFβ1. We report here that the role of TG2 in fibrosis progression can be much more complex. We also report a new family of TG2-specific inhibitors that can not only inhibit protein cross-linking, but also regulate other functions of TG2, thus increasing their potency which can be demonstrated by their effectiveness in inhibiting fibrosis in two different fibrotic in vivo models.

Mesenchymal stem cell-conditioned medium accelerates skin wound healing:an in vitro study of fibroblast and keratinocyte scratch assays

We have used in vitro scratch assays to examine the relative contribution of dermal fibroblasts and keratinocytes in the wound repair process and to test the influence of mesenchymal stem cell (MSC) secreted factors on both skin cell types. Scratch assays were established using single cell and co-cultures of L929 fibroblasts and HaCaT keratinocytes, with wound closure monitored via time-lapse microscopy. Both in serum supplemented and serum free conditions, wound closure was faster in L929 fibroblast than HaCaT keratinocyte scratch assays, and in co-culture the L929 fibroblasts lead the way in closing the scratches. MSC-CM generated under serum free conditions significantly enhanced the wound closure rate of both skin cell types separately and in co-culture, whereas conditioned medium from L929 or HaCaT cultures had no significant effect. This enhancement of wound closure in the presence of MSC-CM was due to accelerated cell migration rather than increased cell proliferation. A number of wound healing mediators were identified in MSC-CM, including TGF-beta1, the chemokines IL-6, IL-8, MCP-1 and RANTES, and collagen type I, fibronectin, SPARC and IGFBP-7. This study suggests that the trophic activity of MSC may play a role in skin wound closure by affecting both dermal fibroblast and keratinocyte migration, along with a contribution to the formation of extracellular matrix.

Loss of Akt activity increases circulating soluble endoglin release in preeclampsia:identification of inter-dependency between Akt-1 and heme oxygenase-1

Aims - Endothelial dysfunction is a hallmark of preeclampsia. Desensitization of the phosphoinositide 3-kinase (PI3K)/Akt pathway underlies endothelial dysfunction and haeme oxygenase-1 (HO-1) is decreased in preeclampsia. To identify therapeutic targets, we sought to assess whether these two regulators act to suppress soluble endoglin (sEng), an antagonist of transforming growth factor-ß (TGF-ß) signalling, which is known to be elevated in preeclampsia. Methods and results - Vascular endothelial growth factor-A (VEGF-A), fibroblast growth factor (FGF-2), angiopoietin-1 (Ang-1), and insulin, which all activate the PI3K/Akt pathway, inhibited the release of sEng from endothelial cells. Inhibition of the PI3K/Akt pathway, by overexpression of phosphatase and tensin homolog (PTEN) or a dominant-negative isoform of Akt (Aktdn) induced sEng release from endothelial cells and prevented the inhibitory effect of VEGF-A. Conversely, overexpression of a constitutively active Akt (Aktmyr) inhibited PTEN and cytokine-induced sEng release. Systemic delivery of Aktmyr to mice significantly reduced circulating sEng, whereas Aktdn promoted sEng release. Phosphorylation of Akt was reduced in preeclamptic placenta and this correlated with the elevated level of circulating sEng. Knock-down of Akt using siRNA prevented HO-1-mediated inhibition of sEng release and reduced HO-1 expression. Furthermore, HO-1 null mice have reduced phosphorylated Akt in their organs and overexpression of Aktmyr failed to suppress the elevated levels of sEng detected in HO-1 null mice, indicating that HO-1 is required for the Akt-mediated inhibition of sEng. Conclusion - The loss of PI3K/Akt and/or HO-1 activity promotes sEng release and positive manipulation of these pathways offers a strategy to circumvent endothelial dysfunction.

Phosphatidylserine-containing liposomes:modulators of rhinovirus induced inflammatory responses

Background: Human rhinoviral infections are major contributors to the healthcare burden associated with acute exacerbations of asthma. We, and others have recently demonstrated that rhinovirus (RV)-induced inflammatory responses are mediated by multiple signalling mechanisms, such as IL-1/MyD88 (1) and TLR3/RIGI (2). We have also previously published work showing that TLR signalling is effectively inhibited by phosphatidylserine-containing liposomes (SAPS), through the disruption of membrane microdomains (3). Evidence has also suggested that membrane microdomains may influence infections with RV. In this study, we explored the ability of SAPS to modulate responses to the natural viral pathogens, RV-1B and RV-16. Method: The immortalized bronchial epithelial cell line, BEAS-2B or primary bronchial epithelial cells were infected with RV-1B or RV-16 at a TCID50/ml of 19107 for 1 h. Immediately following infection, various concentrations of SAPS were added and changes in cytokine release were measured at 24 h. SAPS remained present throughout. Type I and III interferon (IFN) expression and rates of viral replication were measured by quantitative PCR. Virus quantification was also performed using a viral CPE assay, and IFN signalling was measured by western blot. Liposome stability was characterised and intracellular trafficking of fluorescently labelled SAPS in BEAS-2B cells was investigated using confocal microscopy. For in vivo studies, female wt Balb/c mice were pre-treated with SAPS for 2 h prior to infection with RV as previously described and changes in BAL cell number, BAL cytokine production and viral replication were quantified (4). Results: Characterisation of SAPS liposomes by mass spectrometry showed no obvious signs of oxidation over the time period tested, and liposome size remained constant. Preliminary confocal studies revealed that SAPS was rapidly internalised within the cell and was found to associate with intracellular compartments such as the early endosome and golgi. Viral infected BEAS-2B cells co-incubated with SAPS, showed notably impaired responses to RV as assessed by release of CXCL8 and CCL5. SAPS also reduced RV-induced IFNb production and STAT-1 phosphorylation, without significantly influencing viral replication rates. Modest increases in viral particle production were only observed at 48 and 72 h time points. Suppression of viral-induced cytokine production was also observed in primary bronchial epithelial cells and pilot in vivo studies showed that SAPS results in reduced KC production at 24 h post viral infection, and this was associated with reduced neutrophil numbers within the BAL fluid. Conclusion: Our data demonstrates a potential means of modulating inflammatory responses induced by human rhinovirus.

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.