Modulation of the gut microbiota engages antigen cross-presentation to enhance antitumor effects of CAR T cell immunotherapy

Several studies have shown the influence of commensal microbes on T cell function, specifically in the setting of checkpoint immunotherapy for cancer. In this study, we investigated how vancomycin-induced gut microbiota dysbiosis affects chimeric antigen receptor (CAR) T immunotherapy using multiple preclinical models as well as clinical correlates. In two murine tumor models, hematopoietic CD19+-A20 lymphoma and CD19+-B16 melanoma, mice receiving vancomycin in combination with CD19-directed CAR T cell (CART-19) therapy displayed increased tumor control and tumor-associated antigens (TAAs) cross-presentation compared with CART-19 alone. Fecal microbiota transplant from human healthy donors to pre-conditioned mice recapitulated the results obtained in naive gut microbiota mice. Last, B cell acute lymphoblastic leukemia patients treated with CART-19 and exposed to oral vancomycin showed higher CART-19 peak expansion compared with unexposed patients. These results substantiate the role of the gut microbiota on CAR T cell therapy and suggest that modulation of the gut microbiota using vancomycin may improve outcomes after CAR T cell therapy across tumor types.

Biochemical and functional characterization of mutant KRAS epitopes validates this oncoprotein for immunological targeting

Activating RAS missense mutations are among the most prevalent genomic alterations observed in human cancers and drive oncogenesis in the three most lethal tumor types. Emerging evidence suggests mutant KRAS (mKRAS) may be targeted immunologically, but mKRAS epitopes remain poorly defined. Here we employ a multi-omics approach to characterize HLA class I-restricted mKRAS epitopes. We provide proteomic evidence of mKRAS epitope processing and presentation by high prevalence HLA class I alleles. Select epitopes are immunogenic enabling mKRAS-specific TCRαβ isolation. TCR transfer to primary CD8⁺ T cells confers cytotoxicity against mKRAS tumor cell lines independent of histologic origin, and the kinetics of lytic activity correlates with mKRAS peptide-HLA class I complex abundance. Adoptive transfer of mKRAS-TCR engineered CD8⁺ T cells leads to tumor eradication in a xenograft model of metastatic lung cancer. This study validates mKRAS peptides as bona fide epitopes facilitating the development of immune therapies targeting this oncoprotein.

KRAS is commonly mutated at codon 12 in several cancer types, offering a unique opportunity for the development of neoantigen-targeted immunotherapy. Here the authors present a pipeline for the prediction, identification and validation of HLA class-I restricted mutant KRAS G12 peptides, leading to the generation of mutant KRAS-specific T cell receptors for adoptive T cell immunotherapy.

Single-Cell Analyses Identify Brain Mural Cells Expressing CD19 as Potential Off-Tumor Targets for CAR-T Immunotherapies

CD19-directed immunotherapies are clinically effective for treating B cell malignancies but also cause a high incidence of neurotoxicity. A subset of patients treated with chimeric antigen receptor (CAR) T cells or bispecific T cell engager (BiTE) antibodies display severe neurotoxicity, including fatal cerebral edema associated with T cell infiltration into the brain. Here, we report that mural cells, which surround the endothelium and are critical for blood-brain-barrier integrity, express CD19. We identify CD19 expression in brain mural cells using single-cell RNA sequencing data and confirm perivascular staining at the protein level. CD19 expression in the brain begins early in development alongside the emergence of mural cell lineages and persists throughout adulthood across brain regions. Mouse mural cells demonstrate lower levels of Cd19 expression, suggesting limitations in preclinical animal models of neurotoxicity. These data suggest an on-target mechanism for neurotoxicity in CD19-directed therapies and highlight the utility of human single-cell atlases for designing immunotherapies.

Genetic Deletion of IL-19 (Interleukin-19) Exacerbates Atherogenesis in Il19-/-×Ldlr-/- Double Knockout Mice by Dysregulation of mRNA Stability Protein HuR (Human Antigen R)

OBJECTIVE

To test the hypothesis that loss of IL-19 (interleukin-19) exacerbates atherosclerosis. APPROACH AND RESULTS: Il19^-/- mice were crossed into Ldlr^-/- (low-density lipoprotein receptor knock out) mice. Double knockout (dKO) mice had increased plaque burden in aortic arch and root compared with Ldlr^-/- controls after 14 weeks of high-fat diet (HFD). dKO mice injected with 10 ng/g per day rmIL-19 had significantly less plaque compared with controls. qRT-PCR and Western blot analysis revealed dKO mice had increased systemic and intraplaque polarization of T cells and macrophages to proinflammatory T_h1 and M1 phenotypes, and also significantly increased TNF (tumor necrosis factor)-α expression in spleen and aortic arch compared with Ldlr^-/- controls. Bone marrow transplantation suggests that immune cells participate in IL-19 protection. Bone marrow-derived macrophages and vascular smooth muscle cells isolated from dKO mice had a significantly greater expression of inflammatory cytokine mRNA and protein compared with controls. Spleen and aortic arch from dKO mice had significantly increased expression of the mRNA stability protein HuR (human antigen R). Bone marrow-derived macrophage and vascular smooth muscle cell isolated from dKO mice also had greater HuR abundance. HuR stabilizes proinflammatory transcripts by binding AU-rich elements in the 3' untranslated region. Cytokine and HuR mRNA stability were increased in dKO bone marrow-derived macrophage and vascular smooth muscle cell, which was rescued by addition of IL-19 to these cells. IL-19-induced expression of miR133a, which targets and reduced HuR abundance; miR133a levels were lower in dKO mice compared with controls.

CONCLUSIONS

These data indicate that IL-19 is an atheroprotective cytokine which decreases the abundance of HuR, leading to reduced inflammatory mRNA stability.

Abstract 604: Genetic Deletion of Interleukin-19 Exacerbates Atherogenesis and Inflammatory Gene Expression in Ldlr -/- Mice

IL-19 is an anti-inflammatory interleukin and a member of the IL-10 family. Our laboratory has previously shown that IL-19 treatment is able to decrease atherosclerotic plaque burden in Ldlr -/- mice through polarization of T cells and macrophages to their anti-inflammatory phenotypes. We hypothesized that lack of IL-19 would exacerbate atherosclerosis. We observed that the absence of IL-19 results in increased plaque burden in Ldlr -/- x Il19 -/- (DKO) mice when compared to Ldlr -/- controls after 14 weeks of high fat diet (HFD) administration by en face and Oil Red O staining of aorta and aortic root. In a rescue study wherein DKO mice were placed on HFD for 14 weeks and simultaneously injected i.p. with 10ng/g/day of mIL-19 or PBS, DKO mice injected with mIL-19 had significantly less plaque than PBS controls. To test our hypothesis that exacerbated plaque in the DKO was due to an increased pro-inflammatory environment, we performed gene expression analysis from spleen and arch from Ldlr -/- and DKO mice after 14 weeks of HFD, as well as a series of in vitro experiments in isolated Ldlr -/- and DKO VSMCs and BMDMs. qRT-PCR analysis revealed DKO mice have a global and more dramatic local polarization of T cells and macrophages to pro-inflammatory Th1 and M1 phenotypes in the spleen and aortic arch. We stimulated cultured VSMCs and BMDMs with pro-inflammatory stimulus, TNFα, and found that DKO VSMCs express greater levels of TNFα and MCP-1 mRNA compared to Ldlr -/- controls. DKO BMDMs also exhibit increased expression levels of TNFα, as well as IL-1β when compared to Ldlr -/- . Gene expression analysis also demonstrated increased levels of pro-inflammatory mRNA binding protein, human antigen R (HuR) in the DKO spleen and arch. HuR stabilizes pro-inflammatory transcripts by binding ARE elements in the 3’ UTR. Utilizing the RNA synthesis inhibitor actinomycin D in cultured BMDM and VSMC, we observed increased mRNA stability of inflammatory genes in DKO cells when compared to Ldlr -/- by qRT-PCR. These data suggest that IL-19 is an atheroprotective cytokine which dampens inflammatory gene expression by modulation of mRNA stability.

Abstract 404: Induction of MiR133a Expression By IL-19 Targets LDLRAP1 and Reduces Oxidized LDL Uptake in VSMC

Introduction: The transformation of vascular smooth muscle cells (VSMC) into foam cells leading to increased plaque size and decreased stability is a key, yet understudied step in atherogenesis. We reported that Interleukin-19 (IL-19), a novel, anti-inflammatory cytokine, attenuates atherosclerosis by anti-inflammatory effects on VSMC. We tested the hypothesis that one mechanism was reduction in VSMC foam cell formation.

Methods and Results: In this work we report that IL-19 induces expression of miR133a, a muscle-specific miRNA, in VSMC. Although previously unreported, we show that miR133a can target and reduce mRNA abundance, mRNA stability, and protein expression of Low Density Lipoprotein Receptor Adaptor Protein 1, (LDLRAP1), an adaptor protein which functions to internalize the LDL receptor. Mutations in this gene lead to LDL receptor malfunction and cause the Autosomal Recessive Hypercholesterolemia (ARH) disorder in humans. We also show that IL-19 reduces lipid accumulation in VSMC, as well as LDLRAP1 expression and oxLDL uptake in a miR133a-dependent mechanism. We show that LDLRAP1 is expressed in plaque and neointimal VSMC of mouse and human injured arteries. Transfection of miR133a and LDLRAP1 siRNA into VSMC reduces their proliferation and uptake of oxLDL. miR133a is significantly increased in plasma from hyperlipidemic compared with normolipidemic patients.

Summary and conclusions: miR133a targets LDLRAP1 3’UTR and reduces its expression. Expression of miR133a in IL-19 stimulated VSMC represents a previously unrecognized link between vascular lipid metabolism and inflammation, and may represent a therapeutic opportunity to combat vascular inflammatory diseases.

Induction of MiR133a expression by IL-19 targets LDLRAP1 and reduces oxLDL uptake in VSMC

The transformation of vascular smooth muscle cells [VSMC] into foam cells leading to increased plaque size and decreased stability is a key, yet understudied step in atherogenesis. We reported that Interleukin-19 (IL-19), a novel, anti-inflammatory cytokine, attenuates atherosclerosis by anti-inflammatory effects on VSMC. In this work we report that IL-19 induces expression of miR133a, a muscle-specific miRNA, in VSMC. Although previously unreported, we report that miR133a can target and reduce mRNA abundance, mRNA stability, and protein expression of Low Density Lipoprotein Receptor Adaptor Protein 1, (LDLRAP1), an adaptor protein which functions to internalize the LDL receptor. Mutations in this gene lead to LDL receptor malfunction and cause the Autosomal Recessive Hypercholesterolemia (ARH) disorder in humans. Herein we show that IL-19 reduces lipid accumulation in VSMC, and LDLRAP1 expression and oxLDL uptake in a miR133a-dependent mechanism. We show that LDLRAP1 is expressed in plaque and neointimal VSMC of mouse and human injured arteries. Transfection of miR133a and LDLRAP1 siRNA into VSMC reduces their proliferation and uptake of oxLDL. miR133a is significantly increased in plasma from hyperlipidemic compared with normolipidemic patients. Expression of miR133a in IL-19 stimulated VSMC represents a previously unrecognized link between vascular lipid metabolism and inflammation, and may represent a therapeutic opportunity to combat vascular inflammatory diseases.

Interleukin-19 induces angiogenesis in the absence of hypoxia by direct and indirect immune mechanisms

Neovascularization and inflammation are independent biological processes but are linked in response to injury. The role of inflammation-dampening cytokines in the regulation of angiogenesis remains to be clarified. The purpose of this work was to test the hypothesis that IL-19 can induce angiogenesis in the absence of tissue hypoxia and to identify potential mechanisms. Using the aortic ring model of angiogenesis, we found significantly reduced sprouting capacity in aortic rings from IL-19(-/-) compared with wild-type mice. Using an in vivo assay, we found that IL-19(-/-) mice respond to vascular endothelial growth factor (VEGF) significantly less than wild-type mice and demonstrate decreased capillary formation in Matrigel plugs. IL-19 signals through the IL-20 receptor complex, and IL-19 induces IL-20 receptor subunit expression in aortic rings and cultured human vascular smooth muscle cells, but not endothelial cells, in a peroxisome proliferator-activated receptor-γ-dependent mechanism. IL-19 activates STAT3, and IL-19 angiogenic activity in aortic rings is STAT3-dependent. Using a quantitative RT-PCR screening assay, we determined that IL-19 has direct proangiogenic effects on aortic rings by inducing angiogenic gene expression. M2 macrophages participate in angiogenesis, and IL-19 has indirect angiogenic effects, as IL-19-stimulated bone marrow-derived macrophages secrete proangiogenic factors that induce greater sprouting of aortic rings than unstimulated controls. Using a quantitative RT-PCR screen, we determined that IL-19 induces expression of angiogenic cytokines in bone marrow-derived macrophages. Together, these data suggest that IL-19 can promote angiogenesis in the absence of hypoxia by at least two distinct mechanisms: 1) direct effects on vascular cells and 2) indirect effects by stimulation of macrophages.

IL-19 Halts Progression of Atherosclerotic Plaque, Polarizes, and Increases Cholesterol Uptake and Efflux in Macrophages

Atherosclerosis regression is an important clinical goal, and treatments that can reverse atherosclerotic plaque formation are actively being sought. Our aim was to determine whether administration of exogenous IL-19, a Th2 cytokine, could attenuate progression of preformed atherosclerotic plaque and to identify molecular mechanisms. LDLR(-/-) mice were fed a Western diet for 12 weeks, then administered rIL-19 or phosphate-buffered saline concomitant with Western diet for an additional 8 weeks. Analysis of atherosclerosis burden showed that IL-19-treated mice were similar to baseline, in contrast to control mice which showed a 54% increase in plaque, suggesting that IL-19 halted the progression of atherosclerosis. Plaque characterization showed that IL-19-treated mice had key features of atherosclerosis regression, including a reduction in macrophage content and an enrichment in markers of M2 macrophages. Mechanistic studies revealed that IL-19 promotes the activation of key pathways leading to M2 macrophage polarization, including STAT3, STAT6, Kruppel-like factor 4, and peroxisome proliferator-activated receptor γ, and can reduce cytokine-induced inflammation in vivo. We identified a novel role for IL-19 in regulating macrophage lipid metabolism through peroxisome proliferator-activated receptor γ-dependent regulation of scavenger receptor-mediated cholesterol uptake and ABCA1-mediated cholesterol efflux. These data show that IL-19 can halt progression of preformed atherosclerotic plaques by regulating both macrophage inflammation and cholesterol homeostasis and implicate IL-19 as a link between inflammation and macrophage cholesterol metabolism.

Microsecond-pulsed dielectric barrier discharge plasma stimulation of tissue macrophages for treatment of peripheral vascular disease

Angiogenesis is the formation of new blood vessels from pre-existing vessels and normally occurs during the process of inflammatory reactions, wound healing, tissue repair, and restoration of blood flow after injury or insult. Stimulation of angiogenesis is a promising and an important step in the treatment of peripheral artery disease. Reactive oxygen species have been shown to be involved in stimulation of this process. For this reason, we have developed and validated a non-equilibrium atmospheric temperature and pressure short-pulsed dielectric barrier discharge plasma system, which can non-destructively generate reactive oxygen species and other active species at the surface of the tissue being treated. We show that this plasma treatment stimulates the production of vascular endothelial growth factor, matrix metalloproteinase-9, and CXCL 1 that in turn induces angiogenesis in mouse aortic rings in vitro. This effect may be mediated by the direct effect of plasma generated reactive oxygen species on tissue.

CREATION OF OINTMENT COMPOSITIONS CONTAINING PHENOL COMPOUNDS FOR MEDICAL TREATMENT

The research was aimed at studying the possibility of obtaining drug ointments with a potential anti-mycotic activity by using thick extracts obtained from the leaves of fustic, hazel, nut and bark of the oak. There were prepared the ointment compositions on different bases. As a methodology for studying the properties of the obtained ointments, there have been used the studies of colloidal stability and resorption of tanning substances in agar. The obtained results allow for making conclusion that the selected ointments are colloidally stable, and the values of movement of zones of biologically active substances in the agar body are large enough. These data allow for forecasting both the possibility of creating the similar ointment systems and their rather high properties. Based on the obtained data, there have been selected the ointment composition variants for further studies.

Abstract 579: Lack of Interleukin-19 Exacerbates Experimental Atherosclerosis

Interleukin-19 (IL-19) is a Th2 interleukin and a member of an IL-10 subfamily. Previous studies from our laboratory suggest an anti-inflammatory role for IL-19 outside the immune system, and for the vasculature in particular. Significantly more IL-19 is expressed in human atherosclerotic plaque from symptomatic rather than asymptomatic patients. However, addition of rIL-19 to LDLR-/- mice could significantly reduce atherosclerosis, suggesting that IL-19 expression is a compensatory, counter-regulatory mechanism. The purpose of this study was to test the hypothesis that absence of IL-19 results in increased atherosclerosis, and to characterize potential mechanisms for these effects. LDLR-/- mice were crossed with IL-19-/- mice, and homozygous double knock outs (DKO) were fed a high fat atherogenic diet for 14 weeks and compared with LDLR-/- mice. En face oil red O staining demonstrated that loss of IL-19 significantly exacerbated development of plaque in the aortic arch (13.41%+/-1.04 vs 21.13) +/-1.18, P<0.0001 for LDLR and DKO). Preliminary experiments were performed in which DKO were injected with 10ng/g/day rIL-19 or saline as control, and plaque quantitated en face staining. DKO mice rescued with rIL-19 had less plaque compared with saline controls (15.85+/-2.09% vs 22.43+/-2.80%, P=0.07). There was no significant difference in weight gain or serum cholesterol levels between these mice. As a first step to identify mechanisms, differences in cholesterol uptake in macrophage and VSMC were examined. Cholesterol uptake in BMDM from IL-19-/- mice were significantly decreased compared to wild-type controls (P<0.001). Conversely, cholesterol uptake in VSMC from IL-19-/- mice was significantly increased compared to wild-type (P<0.001). These data suggest that IL-19 plays an important part in development of atherosclerosis, with one potential mechanism being alterations in cholesterol homeostasis.

Abstract 146: Administration of Interleukin-19 Halts Progression of Pre-formed Plaque, Polarizes Macrophage, and Increases Macrophage Lipid Uptake

Increased uptake of oxLDL by macrophage is proposed to be an atheroprotective mechanism to reduce plaque formation. It has been proposed that macrophage phenotype may be causative or at least associated with plaque severity. Several macrophage phenotypes have been classified, and M2 macrophage are considered to be anti-inflammatory and reparative. Interleukin-19 is a purported anti-inflammatory, Th2 interleukin, and we previously found that addition of rIL-19 could significantly reduce atherosclerosis in susceptible mice. The purpose of this study was to test the hypothesis that administration of exogenous IL-19 could attenuate progression of pre-formed atherosclerotic plaque, and to identify potential molecular mechanisms. LDLR-/- mice were fed high-fat diet for 12 weeks, then administered rIL-19 (10ng/g/day) or PBS for an additional 8 weeks while still consuming HFD. En face analysis demonstrated that IL-19 could halt, but not reverse existing plaque. M2 macrophage marker expression was significantly increased in aorta and spleen from IL-19 treated mice, in IL-19-treated bone marrow derived macrophage (BMDM) and primary human macrophage. IL-19 significantly decreased expression of inflammatory cytokines TNFa, IL-12p40, MCP-1 and IL-1b mRNA in BMDM. Addition of IL-19 to BMDM significantly increased oxLDL uptake as well as expression of lipid uptake receptors CD36, SRA-1, and SRB-1 in primary human macrophage. IL-19 increased expression and activation of PPARg. Knock down of PPARg significantly decreased IL-19 mediated expression of both lipid uptake receptors and uptake of oxLDL. Collectively, these data show that IL-19 can halt progression of established plaque by at least two mechanisms; M2 macrophage polarization, and increasing expression of lipid scavenger receptors and cholesterol uptake in a PPARg-dependent mechanism, suggesting therapeutic potential for this interleukin.

Interleukin-19 can enhance angiogenesis by Macrophage Polarization

Hypoxia in ischemic limbs typically initiates angiogenic and inflammatory factors to promote angiogenesis in attempt to restore perfusion, and revascularization involves multiple cell types and systems. Macrophage display phenotype plasticity, and can polarize in response to local and systemic cytokine stimuli. M2 macrophage are known to play an important role in angiogenesis and wound healing. While accepted that many pro-inflammatory cytokines induce angiogenesis, the effects of anti-inflammatory interleukins on initiation of angiogenesis are less clear. Interleukin-19 [IL-19] is a presumed anti-inflammatory cytokine, with unknown effects on macrophage polarization. In our recent study, we used several experimental approaches and determined that IL-19 regulated neovascularization in the murine hind-limb ischemia model. In addition to endothelial cells, we found that IL-19 could target and polarize macrophage to the M2 phenotype. IL-19 could induce expression of angiogenic, and reduce expression of anti-angiogenic cytokines in these cells. This is the first study to demonstrate that IL-19 could polarize macrophage, and potentially identifies IL-19 as a therapy to induce angiogenesis in ischemic tissue.

Interleukin-19 increases angiogenesis in ischemic hind limbs by direct effects on both endothelial cells and macrophage polarization

Hypoxia in ischemic limbs typically initiates angiogenic and inflammatory factors to promote angiogenesis in attempt to restore perfusion. There is a gap in our knowledge concerning the role of anti-inflammatory interleukins in angiogenesis, macrophage polarization, and endothelial cell activation. Interleukin-19 is a unique anti-inflammatory Th2 cytokine that promotes angiogenic effects in cultured endothelial cells (EC); the purpose of this study was to characterize a role for IL-19 in restoration of blood flow in hind-limb ischemia, and define potential mechanisms. Hind limb ischemia was induced by femoral artery ligation, and perfusion quantitated using Laser Doppler Perfusion Imaging (LDPI). Wild type mice which received i.p. injections of rIL-19 (10ng/g/day) showed significantly increased levels of perfusion compared to PBS controls. LDPI values were significantly decreased in IL-19(-/-) mice when compared to wild type mice. IL-19(-/-) mice injected with rIL-19 had significantly increased LDPI compared with PBS control mice. Significantly increased capillary density was quantitated in rIL-19 treated mice, and significantly less capillary density in IL-19(-/-) mice. Multiple cell types participate in IL-19 induced angiogenesis. IL-19 treatment of human microvascular EC induced expression of angiogenic cytokines. M2 macrophage marker and VEGF-A expression were significantly increased in macrophage and the spleen from rIL-19 injected mice, and M1 marker expression was significantly increased in the spleen from IL-19(-/-) compared with controls. Plasma VEGF-A levels are higher in rIL-19 injected mice. IL-19 decreased the expression of anti-angiogenic IL-12 in the spleen and macrophage. This study is the first to implicate IL-19 as a novel pro-angiogenic interleukin and suggests therapeutic potential for this cytokine.

IL-19 reduces ligation-mediated neointimal hyperplasia by reducing vascular smooth muscle cell activation

We tested the hypothesis that IL-19, a putative member of the type 2 helper T-cell family of anti-inflammatory interleukins, can attenuate intimal hyperplasia and modulate the vascular smooth muscle cell (VSMC) response to injury. Ligated carotid artery of IL-19 knockout (KO) mice demonstrated a significantly higher neointima/intima ratio compared with wild-type (WT) mice (P = 0.04). More important, the increased neointima/intima ratio in the KO could be reversed by injection of 10 ng/g per day recombinant IL-19 into the KO mouse (P = 0.04). VSMCs explanted from IL-19 KO mice proliferated significantly more rapidly than WT. This could be inhibited by addition of IL-19 to KO VSMCs (P = 0.04 and P < 0.01). IL-19 KO VSMCs migrated more rapidly compared with WT (P < 0.01). Interestingly, there was no type 1 helper T-cell polarization in the KO mouse, but there was significantly greater leukocyte infiltrate in the ligated artery in these mice compared with WT. IL-19 KO VSMCs expressed significantly greater levels of inflammatory mRNA, including IL-1β, tumor necrosis factor α, and monocyte chemoattractant protein-1 in response to tumor necrosis factor α stimulation (P < 0.01 for all). KO VSMCs expressed greater adhesion molecule expression and adherence to monocytes. Together, these data indicate that IL-19 is a previously unrecognized counterregulatory factor for VSMCs, and its expression is an important protective mechanism in regulation of vascular restenosis.

Abstract 45: Interleukin-19 Increases Angiogenic Gene Expression and Perfusion in Ischemic Hind-Limbs

Introduction: Peripheral vascular disease affects over ten million Americans. Hypoxia in ischemic limbs typically initiates angiogenic and inflammatory factors to promote angiogenesis in attempt to restore perfusion. Little is known about the inflammatory nature of angiogenesis particularly with respect to anti-inflammatory factors. Interleukin-19 is a uniquely anti-inflammatory Th2 cytokine that promotes angiogenesis in cellular assays. We hypothesized that IL-19 could drive angiogenesis in vivo; the purpose of this study is to characterize a role for IL-19 in restoration of blood flow in the hind-limb ischemia model, and define potential mechanisms.

Methods and Results: Three complimentary experiments were designed to clarify IL-19’s angiogenic role. 1- C57BL/6 (n=12) were subject to induced hindlimb ischemia by femoral artery ligation and subject to daily i.p. injections of recombinant mouse IL-19 (10ng/g/day) or PBS for 14 days. Mice were subsequently imaged using Laser Doppler Perfusion Imaging (LDPI). Perfusion index was evaluated by comparing values between ligated and unligated contralateral limbs. C57BL/6 mice injected with rIL-19 showed significantly increased levels of perfusion when compared to PBS injected age-matched cohorts (p<0.01 at day 7, <0.05 at day 10). 2- hindlimb ischemia was similarly induced in both C57BL/6 and IL-19-/- mice on a C57BL/6 background. LDPI values are significantly decreased in IL-19-/- mice when compared to C57BL/6 mice (p<0.05 at day 7). 3- IL-19-/- mice subject to limb ischemia were given daily i.p. injections of rIL-19 or PBS. IL-19-/- mice administered rIL-19 trended (P=0.058) higher perfusion when compared to PBS injected control mice. Immunohistochemistry using CD31 antibody on adductor muscle recovered from these mice showed significantly increased capillary density in IL-19 treated mice compared with controls (P<0.05). cDNA microarray analysis of human microvascular endothelial cells treated with IL-19 determined increased expression of angiogenic cytokines, which was verified by qRT-PCR and western blot.

Conclusions: This study is the first to implicate IL-19 as a novel pro-angiogenic cytokine with potential to promote neovascularization and restore blood flow in ischemic tissue.

Attenuation of experimental atherosclerosis by interleukin-19

OBJECTIVE

Interleukin-19 (IL-19) is a putative Th2, anti-inflammatory interleukin. Its expression and potential role in atherogenesis are unknown. IL-19 is not detected in normal artery and is expressed to a greater degree in plaque from symptomatic versus asymptomatic patients, suggesting a compensatory counter-regulatory function. We tested whether IL-19 could reduce atherosclerosis in susceptible mice and identified plausible mechanisms.

APPROACH AND RESULTS

LDLR(-/-) mice fed an atherogenic diet and injected with either 1.0 or 10.0 ng/g per day recombinant mouse IL-19 had significantly less plaque area in the aortic arch compared with controls (P<0.0001). Weight gain, cholesterol, and triglyceride levels were not significantly different. Gene expression in splenocytes from IL-19-treated mice demonstrated immune cell Th2 polarization, with decreased expression of T-bet, interferon-γ, interleukin-1β, and interleukin-12β and increased expression of GATA3 and FoxP3 mRNA. A greater percentage of lymphocytes were Th2 polarized in IL-19-treated mice. Cellular characterization of plaque by immunohistochemistry demonstrated that IL-19-treated mice have significantly less macrophage infiltrate compared with controls (P<0.001). Intravital microscopy revealed significantly less leukocyte adhesion in wild-type mice injected with IL-19 and fed an atherogenic diet compared with controls. Treatment of cultured endothelial cells, vascular smooth muscle cells, and bone marrow-derived macrophages with IL-19 resulted in a significant decrease in chemokine mRNA and mRNA stability protein human antigen R.

CONCLUSIONS

These data suggest that IL-19 is a potent inhibitor of experimental atherosclerosis, with diverse mechanisms including immune cell polarization, decrease in macrophage adhesion, and decrease in gene expression. This may identify IL-19 as a novel therapeutic to limit vascular inflammation.

Abstract 381: IL-19 Inhibits Atherosclerosis in LDLR-/- Mice by Modulating Cholesterol Uptake in Macrophages and Vascular Smooth Muscle Cells

IL-19 is a recently described, putative anti-inflammatory cytokine which had previously been ascribed to be leukocyte specific. IL-19 is not detected in normal artery, but we detected IL-19 in multiple cell types in human atherosclerotic plaque suggesting a role for this interleukin in atherosclerosis. The purpose of this study was to determine whether administration of exogenous IL-19 could attenuate development of pre-formed atherosclerotic plaque, and to identify potential molecular mechanisms. LDLR-/- mice were fed high-fat diet for 12 weeks and then administered with 10ng/g/day IL-19 or PBS for an additional 8 weeks. En face analysis demonstrated that IL-19 could halt, but not reverse existing plaque (26.7+/-1.7%, 41.03+/-3.1%, 23.70+/-2.6% for baseline, PBS control, and IL-19-treated mice). Foam cell formation by macrophages and vascular smooth muscle cells (VSMC) is a hallmark event during atherosclerosis. Nothing has been reported regarding IL-19 effects on macrophage or VSMC lipid uptake; we therefore investigated whether IL-19 affects macrophage and VSMC cholesterol handling. Addition of IL-19 to wild-type bone marrow derived macrophages (BMDM) significantly promoted oxLDL uptake, conversely, BMDM from IL-19-/- mice had significantly less oxLDL uptake compared to wild-type BMDM. Addition of IL-19 to wild type BMDM significantly increased expression of scavenger receptor B1 (SR-B1), and decreased expression of inflammatory cytokines TNFα, IL-12b, MCP1. Interestingly, converse results were obtained with VSMC, as addition of IL-19 to wild-type VSMC decreased uptake of oxLDL ( p<0.05 ) and decreased expression of scavenger receptor CD36. VSMC isolated from IL-19-/- mice had increased uptake of oxLDL (p<0.0001). It is reported that M2 macrophages participate in plaque regression. IL-19 decreased IL-12b and significantly promoted the polarization of anti-inflammatory M2 phenotype in BMDM as evidenced by the increased expression of YM1 and IL-10 mRNA. These data demonstrate that IL-19 can inhibit progression of existing atherosclerotic plaque by modulating lipid metabolism in VSMC and macrophages and by promoting macrophage differentiation into an alternative, anti-inflammatory M2 phenotype.

Abstract 459: Attenuation of Experimental Atherosclerosis by Systemic Administration of Interleukin-19

Introduction: IL-19 is a newly described Th2 interleukin which had previously been ascribed to be inflammatory cell-specific. Ours is the only laboratory to investigate a role for this interleukin in vascular biology. The hypothesis of this study is that IL-19 can attenuate atherosclerosis through the potential mechanism of dampening leukocyte-endothelial cell interactions.

Methods and Results: IL-19 is not detected in normal artery, but is highly expressed in multiple cell types in atherosclerotic plaque suggesting a role for this interleukin in development of atherosclerosis. Five month old LDLR -/- mice were fed an atherogenic diet and injected i.p. with either 1.0ng/g/day IL-19, 10.0ng/g/day IL-19, or PBS for 12 weeks. Mice receiving systemic IL-19 injections developed significantly less atherosclerotic plaque in the aortic arch compared with control mice (17.7+/-1.7% vs 5.3+/-1.1%, p<0.0001 for 1.0ng/g/day, and 18.5+/-1.5% vs 2.2+/-0.3%, p<0.0001 for 10.0ng/g/day). To determine if IL-19 could cause plaque regression, 10.0ng/g/day IL-19 or PBS was administered to LDLR -/- mice which had previously been fed an atherogenic diet for 14 weeks. After 8 weeks of treatment, a significant difference of p<0.0025 between the no treatment and PBS groups, and a significant difference of p<0.0014 between PBS and IL-19 treated groups was noted, but no significant difference between the no treatment and IL-19 treated groups was observed. No difference in serum cholesterol, triglycerides, or body weight was noted between the control and IL-19 groups. Immunohistochemical staining of the aortic root from these mice for the macrophage marker F4/80 demonstrates IL-19 treated mice have significantly less macrophage infiltrate compared with mice injected with PBS (36.3+/-2.3% vs 20.0+/-2.7%, p<0.0004). Wild-type mice were fed an atherogenic diet and injected with 1.0ng/g/day IL-19 for 12 weeks, and intravital microscopy of leukocyte adhesion indicates that IL-19 decreases leukocyte-endothelial cell interactions in vivo.

Conclusion: When taken together, these data suggest an important role for IL-19 in inhibition, but not regression, of atherosclerotic plaque in vivo. A potential mechanism is that IL-19 can decrease leukocyte-endothelial cell interaction.

Heterologous protein incites abnormal plasma cell accumulation and autoimmunity in MRL-MpJ mice

Although it is evident that there is complex interplay among genetic and environmental factors contributing to systemic autoimmunity, the events inciting autoreactivity are incompletely understood. Previously we demonstrated that MRL-MpJ mice posses a genetic background susceptible to autoimmunity development under conditions of altered inhibitory signaling. To gain better understanding of the influence of exogenous factors on autoreactivity in susceptible individuals, young MRL-MpJ mice were challenged with a single injection of heterologous protein and evaluated for evidence of autoimmunity. We found that MRL-MpJ mice developed high titer serum reactivity to DNA within 1 week of protein administration reaching maximal levels within 1 month. Importantly, the level of autoimmunity was sustained for an extended period of time (6 months). This was accompanied by a substantial increase in germinal center B cell and plasma cell numbers. In contrast, control mice showed no change in autoreactivity or lymphocyte homeostasis. Autoimmunity was dependent on marginal zone B cells as their depletion reduced serum auto-reactivity after challenge, thus suggesting immune stimulation with heterologous proteins can precipitate loss of B cell tolerance and autoimmunity in genetically prone individuals. This model may provide an important tool to further investigate the mechanisms whereby environmental stimuli trigger autoimmune reactivity in susceptible hosts.

Interleukin-19 (IL-19) induces heme oxygenase-1 (HO-1) expression and decreases reactive oxygen species in human vascular smooth muscle cells

Heme oxygenase-1 (HO-1) has potent anti-inflammatory activity and recognized vascular protective effects. We have recently described the expression and vascular protective effects of an anti-inflammatory interleukin (IL-19), in vascular smooth muscle cells (VSMC) and injured arteries. The objective of this study was to link the anti-inflammatory effects of IL-19 with HO-1 expression in resident vascular cells. IL-19 induced HO-1 mRNA and protein in cultured human VSMC, as assayed by quantitative RT-PCR, immunoblot, and ELISA. IL-19 does not induce HO-1 mRNA or protein in human endothelial cells. IL-19 activates STAT3 in VSMC, and IL-19-induced HO-1 expression is significantly reduced by transfection of VSMC with STAT3 siRNA or mutation of the consensus STAT binding site in the HO-1 promoter. IL-19 treatment can significantly reduce ROS-induced apoptosis, as assayed by Annexin V flow cytometry. IL-19 significantly reduced ROS concentrations in cultured VSMC. The IL-19-induced reduction in ROS concentration is attenuated when HO-1 is reduced by siRNA, indicating that the IL-19-driven decrease in ROS is mediated by HO-1 expression. IL-19 reduces vascular ROS in vivo in mice treated with TNFα. This points to IL-19 as a potential therapeutic for vascular inflammatory diseases and a link for two previously unassociated protective processes: Th2 cytokine-induced anti-inflammation and ROS reduction.

Anti-inflammatory cytokine interleukin-19 inhibits smooth muscle cell migration and activation of cytoskeletal regulators of VSMC motility

Vascular smooth muscle cell (VSMC) migration is an important cellular event in multiple vascular diseases, including atherosclerosis, restenosis, and transplant vasculopathy. Little is known regarding the effects of anti-inflammatory interleukins on VSMC migration. This study tested the hypothesis that an anti-inflammatory Th2 interleukin, interleukin-19 (IL-19), could decrease VSMC motility. IL-19 significantly decreased platelet-derived growth factor (PDGF)-stimulated VSMC chemotaxis in Boyden chambers and migration in scratch wound assays. IL-19 significantly decreased VSMC spreading in response to PDGF. To determine the molecular mechanism(s) for these cellular effects, we examined the effect of IL-19 on activation of proteins that regulate VSMC cytoskeletal dynamics and locomotion. IL-19 decreased PDGF-driven activation of several cytoskeletal regulatory proteins that play an important role in smooth muscle cell motility, including heat shock protein-27 (HSP27), myosin light chain (MLC), and cofilin. IL-19 decreased PDGF activation of the Rac1 and RhoA GTPases, important integrators of migratory signals. IL-19 was unable to inhibit VSMC migration nor was able to inhibit activation of cytoskeletal regulatory proteins in VSMC transduced with a constitutively active Rac1 mutant (RacV14), suggesting that IL-19 inhibits events proximal to Rac1 activation. Together, these data are the first to indicate that IL-19 can have important inhibitory effects on VSMC motility and activation of cytoskeletal regulatory proteins. This has important implications for the use of anti-inflammatory cytokines in the treatment of vascular occlusive disease.

The anti-inflammatory cytokine interleukin 19 is expressed by and angiogenic for human endothelial cells

OBJECTIVE

To characterize the expression and function of interleukin (IL) 19, a recently described T-helper 2 anti-inflammatory IL, on endothelial cell (EC) pathophysiological features.

METHODS AND RESULTS

The expression and effects of anti-inflammatory ILs on EC activation and development of angiogenesis are uncharacterized. We demonstrate by immunohistochemistry and immunoblot that IL-19 is expressed in inflamed, but not normal, human coronary endothelium and can be induced in cultured human ECs by serum and basic fibroblast growth factor. IL-19 is mitogenic and chemotactic, and it promotes EC spreading. IL-19 activates the signaling proteins STAT3, p44/42, and Rac1. In functional ex vivo studies, IL-19 promotes cordlike structure formation of cultured ECs and enhances microvessel sprouting in the mouse aortic ring assay. IL-19 induces tube formation in gelatinous protein (Matrigel) plugs in vivo.

CONCLUSIONS

To our knowledge, these data are the first to report expression of the anti-inflammatory agent, IL-19, in ECs; and the first to indicate that IL-19 is mitogenic and chemotactic for ECs and can induce the angiogenic potential of ECs.