Jörg J. Goronzy

Giant-Cell Arteritis and Polymyalgia Rheumatica

A 79-year-old woman presents with new-onset pain in her neck and both shoulders. She takes 7.5 mg of prednisone per day for giant-cell arteritis. Occipital tenderness and diplopia developed 11 months before presentation. At that time, her erythrocyte sedimentation rate was elevated, at 78 mm per hour, and a temporal-artery biopsy revealed granulomatous arteritis. The diplopia resolved after 6 days of treatment with 60 mg of prednisone daily. Neither headache nor visual symptoms developed when the glucocorticoids were tapered. How should this patient’s care be managed?

Monoclonal T-Cell Proliferation and Plaque Instability in Acute Coronary Syndromes

BACKGROUND Unstable angina (UA) is associated with systemic inflammation and with expansion of interferon-gamma-producing T lymphocytes. The cause of T-cell activation and the precise role of activated T cells in plaque instability are not understood. METHODS AND RESULTS Peripheral blood T cells from 34 patients with stable angina and 34 patients with UA were compared for the distribution of functional T-cell subsets by flow cytometric analysis. Clonality within the T-cell compartment was identified by T-cell receptor spectrotyping and subsequent sequencing. Tissue-infiltrating T cells were examined in extracts from coronary arteries containing stable or unstable plaque. The subset of CD4(+)CD28(null) T cells was expanded in patients with UA and infrequent in patients with stable angina (median frequencies: 10.8% versus 1.5%, P<0.001). CD4(+)CD28(null) T cells included a large monoclonal population, with 59 clonotypes isolated from 20 UA patients. T-cell clonotypes from different UA patients used antigen receptors with similar sequences. T-cell receptor sequences derived from monoclonal T-cell populations were detected in the culprit but not in the nonculprit lesion of a patient with fatal myocardial infarction. CONCLUSIONS UA is associated with the emergence of monoclonal T-cell populations, analogous to monoclonal gammopathy of unknown significance. Shared T-cell receptor sequences in clonotypes of different patients implicate chronic stimulation by a common antigen, for example, persistent infection. The unstable plaque but not the stable plaque is invaded by clonally expanded T cells, suggesting a direct involvement of these lymphocytes in plaque disruption.

Vessel-Specific Toll-Like Receptor Profiles in Human Medium and Large Arteries

Background— Inflammatory vasculopathies, ranging from the vasculitides (Takayasu arteritis, giant cell arteritis, and polyarteritis nodosa) to atherosclerosis, display remarkable target tissue tropisms for selected vascular beds. Molecular mechanisms directing wall inflammation to restricted anatomic sites within the vascular tree are not understood. We have examined the ability of 6 different human macrovessels (aorta and subclavian, carotid, mesenteric, iliac, and temporal arteries) to initiate innate and adaptive immune responses by comparing pathogen-sensing and T-cell-stimulatory capacities. Methods and Results— Gene expression analysis for pathogen-sensing Toll-like receptors (TLRs) 1 to 9 showed vessel-specific profiles, with TLR2 and TLR4 ubiquitously present, TLR7 and TLR9 infrequent, and TLR1, TLR3, TLR5, TLR6, and TLR8 expressed in selective patterns. Experiments with vessel walls stripped of the intimal or adventitial layer identified dendritic cells at the media-adventitia junction as the dominant pathogen sensors. In human artery-severe combined immunodeficiency (SCID) mouse chimeras, adoptively transferred human T cells initiated vessel wall inflammation if wall-embedded dendritic cells were conditioned with TLR ligands. Wall-infiltrating T cells displayed vessel-specific activation profiles with differential production of CD40L, lymphotoxin-&agr;, and interferon-&ggr;. Vascular bed-specific TLR fingerprints were functionally relevant, as exemplified by differential responsiveness of iliac and subclavian vessels to TLR5 but not TLR4 ligands. Conclusions— Populated by indigenous dendritic cells, medium and large human arteries have immune-sensing and T-cell-stimulatory functions. Each vessel in the macrovascular tree exhibits a distinct TLR profile and supports selective T-cell responses, imposing vessel-specific risk for inflammatory vasculopathies.

Th17 and Th1 T-cell responses in giant cell arteritis.

Background— In giant cell arteritis (GCA), vasculitic damage of the aorta and its branches is combined with a syndrome of intense systemic inflammation. Therapeutically, glucocorticoids remain the gold standard because they promptly and effectively suppress acute manifestations; however, they fail to eradicate vessel wall infiltrates. The effects of glucocorticoids on the systemic and vascular components of GCA are not understood. Methods and Results— The immunoprofile of untreated and glucocorticoid-treated GCA was examined in peripheral blood and temporal artery biopsies with protein quantification assays, flow cytometry, quantitative real-time polymerase chain reaction, and immunohistochemistry. Plasma interferon-&ggr; and interleukin (IL)-17 and frequencies of interferon-&ggr;-producing and IL-17-producing T cells were markedly elevated before therapy. Glucocorticoid treatment suppressed the Th17 but not the Th1 arm in the blood and the vascular lesions. Analysis of monocytes/macrophages in the circulation and in temporal arteries revealed glucocorticoid-mediated suppression of Th17-promoting cytokines (IL-1&bgr;, IL-6, and IL-23) but sparing of Th1-promoting cytokines (IL-12). In human artery-severe combined immunodeficiency mouse chimeras, in which patient-derived T cells cause inflammation of engrafted human temporal arteries, glucocorticoids were similarly selective in inhibiting Th17 cells and leaving Th1 cells unaffected. Conclusions— Two pathogenic pathways mediated by Th17 and Th1 cells contribute to the systemic and vascular manifestations of GCA. IL-17-producing Th17 cells are sensitive to glucocorticoid-mediated suppression, but interferon-&ggr;-producing Th1 responses persist in treated patients. Targeting steroid-resistant Th1 responses will be necessary to resolve chronic smoldering vasculitis. Monitoring Th17 and Th1 frequencies can aid in assessing disease activity in GCA.

Pathogen-Sensing Plasmacytoid Dendritic Cells Stimulate Cytotoxic T-Cell Function in the Atherosclerotic Plaque Through Interferon-α

Background— Unstable atherosclerotic plaque is characterized by an infiltrate of inflammatory cells. Both macrophages and T cells have been implicated in mediating the tissue injury leading to plaque rupture; however, signals regulating their activation remain unidentified. Infectious episodes have been suspected to render plaques vulnerable to rupture. We therefore explored whether plasmacytoid dendritic cells (pDCs) that specialize in sensing bacterial and viral products can regulate effector functions of plaque-residing T cells and thus connect host infection and plaque instability. Methods and Results— pDCs were identified in 53% of carotid atheromas (n=30) in which they localized to the shoulder region and produced the potent immunoregulatory cytokine interferon (INF)-&agr;. IFN-&agr; transcript concentrations in atheroma tissues correlated strongly with plaque instability (P<0.0001). Plaque-residing pDCs responded to pathogen-derived motifs, CpG-containing oligodeoxynucleotides binding to toll-like receptor 9, with enhanced IFN-&agr; transcription (P=0.03) and secretion (P=0.007). IFN-&agr; emerged as a potent regulator of T-cell function, even in the absence of antigen recognition. Specifically, IFN-&agr; induced a 10-fold increase of tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) on the surface of CD4 T cells (P<0.0001) and enabled them to effectively kill vascular smooth muscle cells (P=0.0003). Conclusions— pDCs in atherosclerotic plaque sense microbial motifs and amplify cytolytic T-cell functions, thus providing a link between host-infectious episodes and acute immune-mediated complications of atherosclerosis.

De Novo Expression of Killer Immunoglobulin-Like Receptors and Signaling Proteins Regulates the Cytotoxic Function of CD4 T Cells in Acute Coronary Syndromes

&NA; The inflammatory infiltrate in atherosclerotic plaque is composed of T cells and macrophages. CD4+ T cells with a unique phenotype, CD4+CD28null, are preferentially recruited into culprit lesions. These T cells are distinct from classic CD4+CD28+ T cells in gene expression and function, including their ability to mediate cytolysis. In this study, we have investigated the regulation of CD4+CD28null T‐cell cytolytic function. In patients with acute coronary syndromes (ACS), CD4+CD28null T cells express killer immunoglobulin‐like receptors (KIRs). KIRs encompass a polymorphic family of receptors that recognize HLA class I molecules and have been implicated in self‐tolerance. CD4+CD28null T‐cell clones from patients with ACS and age‐matched controls were compared for their KIR‐expression profile. T‐cell clones derived from the patients expressed a broader spectrum of KIRs (P<0.001) with preference for the stimulatory variant, CD158j. Additionally, CD4+ T‐cell clones from patients but not those from controls acquired de novo expression of the DAP12 molecule, an adapter chain that transmits CD158j‐derived signals. Cumulative expression of CD158j and DAP12 endowed cytolytic competence on CD4+CD28null T cells, allowing them to kill in the absence of T‐cell receptor triggering. Our data demonstrate that CD4+CD28null T cells in ACS are characterized by a unique gene expression profile. Consequently, these T cells acquire cytolytic capability that can bypass the need for T‐cell receptor triggering and, thus, impose a threat to self‐tolerance. (Circ Res. 2003;93:106‐113.)

Synergistic Proinflammatory Effects of the Antiviral Cytokine Interferon-α and Toll-Like Receptor 4 Ligands in the Atherosclerotic Plaque

Background— Interferon (IFN)-&agr; is a pluripotent inflammatory cytokine typically induced by viral infections. In rupture-prone atherosclerotic plaques, plasmacytoid dendritic cells produce IFN-&agr;. In the present study we explored the contribution of IFN-&agr; to inflammation and tissue injury in the plaque microenvironment. Methods and Results— In 53% of carotid plaques (n=30), CD123+ plasmacytoid dendritic cells clustered together with CD11c+ myeloid dendritic cells, a distinct dendritic cell subset specialized in sensing danger signals from bacteria and tissue breakdown. Tissue concentrations of IFN-&agr; and tumor necrosis factor (TNF)-&agr; transcripts were tightly correlated (r=0.76, P<0.001), suggesting a regulatory role of IFN-&agr; in TNF-&agr; production. Plaque tissue stimulation with CpG ODN, a Toll-like receptor (TLR) 9 ligand, increased IFN-&agr; production (57.8±23.7 versus 25.9±8.6 pg/mL; P<0.001), whereas the TLR4 ligand lipopolysaccharide induced TNF-&agr; secretion (225.1±3.0 versus 0.7±0.2 pg/mL; P<0.001). Treating plaque tissue with IFN-&agr; markedly enhanced lipopolysaccharide-triggered TNF-&agr; secretion (559.0±25.9 versus 225.1±3.0 pg/mL; P<0.001). IFN-&agr; pretreatment also amplified the effects of lipopolysaccharide on interleukin-12, interleukin-23, and matrix metalloproteinase-9, suggesting that the antiviral cytokine sensitized myeloid dendritic cells and macrophages toward TLR4 ligands. Mechanistic studies demonstrated that IFN-&agr; modulated the myeloid dendritic cell response pattern by upregulating TLR4 expression (P<0.001) involving both the STAT (signal transducer and activator of transcription) and the PI(3)K pathway. Conclusions— In the atherosclerotic plaque, IFN-&agr; functions as an inflammatory amplifier. It sensitizes antigen-presenting cells toward pathogen-derived TLR4 ligands by upregulating TLR4 expression and intensifies TNF-&agr;, interleukin-12, and matrix metalloproteinase-9 production, all implicated in plaque destabilization. Thus, IFN-&agr;–inducing pathogens, even when colonizing distant tissue sites, threaten the stability of inflamed atherosclerotic plaque.

Tissue-Destructive Macrophages in Giant Cell Arteritis

Giant cell arteritis (GCA) is an inflammatory vasculopathy in which T cells and macrophages infiltrate the wall of medium and large arteries. Clinical consequences such as blindness and stroke are related to arterial occlusion. Formation of aortic aneurysms may result from necrosis of smooth muscle cells and fragmentation of elastic membranes. The molecular mechanisms of arterial wall injury in GCA are not understood. To identify mechanisms of arterial damage, gene expression in inflamed and unaffected temporal artery specimens was compared by differential display polymerase chain reaction. Genes differentially expressed in arterial lesions included 3 products encoded by the mitochondrial genome. Immunohistochemistry with antibodies specific for a 65-kDa mitochondrial antigen revealed that increased expression of mitochondrial products was characteristic of multinucleated giant cells and of CD68+ macrophages that cluster in the media and at the media-intima junction. 4-Hydroxy-2-nonenal adducts, products of lipid peroxidation, were detected on smooth muscle cells and on tissue infiltrating cells, in close proximity to multinucleated giant cells and CD68+ macrophages. Also, giant cells and macrophages with overexpression of mitochondrial products were able to synthesize metalloproteinase-2. Our data suggest that in the vascular lesions characteristic for GCA, a subset of macrophages has the potential to support several pathways of arterial injury, including the release of reactive oxygen species and the production of metalloproteinase-2. This macrophage subset is topographically defined and is also identified by overexpression of mitochondrial genes. Because these macrophages have a high potential to promote several mechanisms of arterial wall damage, they should be therapeutically targeted to prevent blood vessel destruction.

Molecular Fingerprint of Interferon-γ Signaling in Unstable Angina

BackgroundActivation of circulating monocytes in patients with acute coronary syndromes may reflect exposure to bacterial products or stimulation by cytokines such as IFN-&ggr;. IFN-&ggr; induces phosphorylation and nuclear translocation of transcription factor STAT-1, which initiates a specific program of gene induction. To explore whether monocyte activation is IFN-&ggr; driven, patients with unstable (UA) or stable angina (SA) were compared for nuclear translocation of STAT-1 complexes and upregulation of IFN-&ggr;-inducible genes CD64 and IP-10. Methods and ResultsPeripheral blood mononuclear cells were stained for expression of CD64 on CD14+ monocytes and analyzed by PCR for transcription of IP-10. Expression of CD64 was significantly increased in patients with UA. Monocytes from UA patients remained responsive to IFN-&ggr; in vitro, with accelerated transcriptional competency of CD64. IP-10-specific sequences were spontaneously detectable in 82% of the UA patients and 15% of SA patients (P <0.001). Most importantly, STAT-1 complexes were found in nuclear extracts prepared from freshly isolated monocytes of patients with UA, which provides compelling evidence for IFN-&ggr; signaling in vivo. ConclusionsMonocytes from UA patients exhibit a molecular fingerprint of recent IFN-&ggr; triggering, such as nuclear translocation of STAT-1 complexes and upregulation of IFN-&ggr;-inducible genes CD64 and IP-10, which suggests that monocytes are activated, at least in part, by IFN-&ggr;. IFN-&ggr; may derive from stimulated T lymphocytes, which implicates specific immune responses in the pathogenesis of acute coronary syndromes.

Toll-Like Receptors 4 and 5 Induce Distinct Types of Vasculitis

Large vessel vasculitides, such as Takayasu arteritis and giant cell arteritis, affect vital arteries and cause clinical complications by either luminal occlusion or vessel wall destruction. Inflammatory infiltrates, often with granulomatous arrangements, are distributed as a panarteritis throughout all of the artery’s wall layers or cluster in the adventitia as a perivasculitis. Factors determining the architecture and compartmentalization of vasculitis are unknown. Human macrovessels are populated by indigenous dendritic cells (DCs) positioned in the adventitia. Herein, we report that these vascular DCs sense bacterial pathogens and regulate the patterning of the emerging arteritis. In human temporal artery–SCID chimeras, lipopolysaccharides stimulating Toll-like receptor (TLR)4 and flagellin stimulating TLR5 trigger vascular DCs and induce T-cell recruitment and activation. However, the architecture of the evolving inflammation is ligand-specific; TLR4 ligands cause transmural panarteritis and TLR5 ligands promote adventitial perivasculitis. Underlying mechanisms involve selective recruitment of functional T cell subsets. Specifically, TLR4-mediated DC stimulation markedly enhances production of the chemokine CCL20, biasing recruitment toward CCL20-responsive CCR6+ T cells. In adoptive transfer experiments, CCR6+ T cells produce an arteritis pattern with media-invasive T cells damaging vascular smooth muscle cells. Also, CCR6+ T cells dominate the vasculitic infiltrates in patients with panarteritic giant cell arteritis. Thus, depending on the original danger signal, vascular DCs edit the emerging immune response by differentially recruiting specialized T effector cells and direct the disease process toward distinct types of vasculitis.