IL-12 and IL-18 are increased and stimulate IFN-gamma production in sarcoid lungs

Increased IL-17A expression in granulomas and in circulating memory T cells in sarcoidosis

OBJECTIVE

Sarcoidosis is a systemic inflammatory disorder characterized by granulomas. Although the aetiology is unknown, sarcoidosis is thought to be mediated by Th1 lymphocytes. Recently, IL-17A has been implicated in granuloma formation in various diseases, including tuberculosis. Therefore, we hypothesized that Th17 cells play a role in sarcoidosis, paralleling recent findings in autoimmune diseases such as RA. The aim of our study was to investigate the role of Th17 cells in sarcoidosis.

METHODS

T cells were investigated by intracellular flow cytometry and immunohistochemistry, in blood, bronchoalveolar lavages (BALs) and bronchial mucosal biopsies from a cohort of newly diagnosed sarcoidosis patients and healthy controls.

RESULTS

Circulating memory CD4(+) T-cell populations of sarcoidosis patients contained significantly increased proportions of IL-17A(+) cells when compared with healthy controls. Interestingly, proportions of IL-17A/IFN-γ and IL-17A/IL-4 double-producing cells were significantly increased in blood of sarcoidosis patients and were present in substantial numbers in BAL. In granuloma-containing, but not in non-granulomatous sarcoidosis biopsies, we found significantly increased numbers of IL-17A(+) T cells, located in and around granulomas throughout the lamina propria. IL-22(+) T cells were increased in the subepithelial layer.

CONCLUSIONS

Enhanced IL-17A expression in granulomas and the presence of IL-17A(+), IL-17A(+)IFN-γ(+) and IL-17A(+)IL-4(+)memory Th cells in the circulation and BAL indicate Th17 cell involvement in granuloma induction or maintenance in sarcoidosis. Therefore, neutralization of IL-17A activity may be a novel strategy to treat sarcoidosis.

Tumor necrosis factor-alpha inhibitor treatment for sarcoidosis

Sarcoidosis is a chronic multisystem disease of unknown etiology, characterized by noncaseating granulomatous infiltration of virtually any organ system. Treatment is often undertaken in an attempt to resolve symptoms or prevent progression to organ failure. Previous studies have suggested a prominent role for tumor necrosis factor-alpha (TNF-α) in the inflammatory process seen in sarcoidosis. TNF-α and interleukin-1 are released by alveolar macrophages in patients with active lung disease. Corticosteroids have proved to be efficacious in the treatment of sarcoidosis, possibly by suppressing the production of TNF-α and other cytokines. Three agents are currently available as specific TNF antagonists: etanercept, infliximab, and adalimumab. Although data from noncomparative trials suggest that all three have comparable therapeutic effects in rheumatoid arthritis, their effects in a granulomatous disease such as sarcoidosis are less consistent. In this review, current data on the effectiveness are summarized.

Discovery and mechanism of ustekinumab: a human monoclonal antibody targeting interleukin-12 and interleukin-23 for treatment of immune-mediated disorders

Monoclonal antibody (mAb) therapy was first established upon the approval of a mouse antibody for treatment of human acute organ rejection. However, the high incidence of immune response against the mouse mAb restricted therapeutic utility. Development of chimeric, "humanized" and human mAbs broadened therapeutic application to immune-mediated diseases requiring long-term treatment. Indeed, mAb therapeutics targeting soluble cytokines are highly effective in numerous immune-mediated disorders. A recent example is ustekinumab, a first-in-class therapeutic human immunoglobulin G1 kappa mAb that binds to the interleukins (IL)-12 and IL-23, cytokines that modulate lymphocyte function, including T-helper (Th) 1 and Th17 cell subsets. Ustekinumab was generated via recombinant human IL-12 immunization of human immunoglobulin (hu-Ig) transgenic mice. Ustekinumab binds to the p40 subunit common to IL-12 and IL-23 and prevents their interaction with the IL-12 receptor β1 subunit of the IL-12 and IL-23 receptor complexes. Ustekinumab is approved for treatment of moderate-to-severe plaque psoriasis and has demonstrated efficacy in Crohn disease and psoriatic arthritis. The clinical characterization of ustekinumab continues to clarify our understanding of human immune pathologies and may offer a novel therapeutic option for certain immune-mediated diseases.

Molecular profiling and gene expression analysis in cutaneous sarcoidosis: the role of interleukin-12, interleukin-23, and the T-helper 17 pathway

BACKGROUND

Cutaneous sarcoidosis (CS) skin provides relatively noninvasive access to granulomatous sarcoidosis tissue.

OBJECTIVE

We sought to explore the role of the T-helper (Th)1 and Th17 pathways in sarcoidosis.

METHODS

We used molecular profiling and gene expression analysis to analyze the Th1 and Th17 pathways and other immune-mediated pathways in CS. Molecular profiles were obtained from sarcoidosis skin lesions (lesional skin [LS]), unaffected skin from patients with CS (non-LS), and the skin of healthy control subjects. Whole blood was collected to compare the molecular profile of sarcoidosis skin lesions and whole blood.

RESULTS

Twenty participants were enrolled: 15 with active CS and 5 healthy volunteers. Microarray analyses comparing non-LS and healthy volunteer skin with LS showed several thousand genes differentially expressed (≥2-fold change false discovery rate, P < .01). Targeted selections of genes associated with Th1 and Th17 phenotypes showed a strong Th1 profile of sarcoidosis and expression of interleukin (IL)-23 and IL-23R with limited expression of other Th17 pathway genes. IL-21 and signal transducer and activator of transcription 3 (STAT3) were also dysregulated in skin and whole blood, providing additional evidence for involvement of the IL-12 pathway and potential activation of the Th17 pathway.

LIMITATIONS

Measurements were made at a single point in time and may not identify mechanisms that may be identified in patients followed up longitudinally.

CONCLUSION

These findings provide novel insight into the dysregulated pathways that may be involved in the pathogenesis of sarcoidosis.

PPARs in alveolar macrophage biology

PPARs, most notably PPAR-gamma, play a crucial role in regulating the activation of alveolar macrophages, which in turn occupy a pivotal place in the immune response to pathogens and particulates drawn in with inspired air. In this review, we describe the dual role of the alveolar macrophage as both a first-line defender through its phagocytotic activity and a regulator of the immune response. Depending on its state of activation, the alveolar macrophage may either enhance or suppress different aspects of immune function in the lung. We then review the role of PPAR-gamma and its ligands in deactivating alveolar macrophages-thus limiting the inflammatory response that, if unchecked, could threaten the essential respiratory function of the alveolus-while upregulating the cell's phagocytotic activity. Finally, we examine the role that inadequate or inappropriate PPAR-gamma responses play in specific lung diseases.

Development of the IL-12/23 antagonist ustekinumab in psoriasis: past, present, and future perspectives

The development of ustekinumab as a first-in-class anti-interleukin (IL) 12/23p40 therapeutic agent for psoriasis represents an important example of modern and rational drug design and development. Psoriasis is a chronic, systemic, immune-mediated skin disorder with considerable clinical, psychosocial, and economic burden. Ustekinumab is a human monoclonal antibody (mAb) that binds the p40 subunit common to IL-12 and IL-23, key cytokines in psoriasis pathogenesis. The therapeutic mAb was developed using human gamma-1 immunoglobulin (IgG)-expressing transgenic mice, which created a molecule with endogenous IgG(1) biologic properties and low immunogenicity. Ustekinumab was well tolerated in clinical studies and yielded rapid, significant, and sustained efficacy plus improved quality of life/work performance and reduced depression/anxiety. Its pharmacologic properties afford the most convenient dosing regimen among approved biologics, representing a significant advancement in the treatment of moderate to severe psoriasis. Ustekinumab also holds promise for other immune-mediated disorders with significant unmet need.

Cytokine modulators in the treatment of sarcoidosis

Sarcoidosis is a granulomatous lung disease in which several cytokines play a pivotal pathogenetic role. Steroid-resistant disease can be treated with immunosuppressive drugs, antimalarial therapies and recently with anti-TNFα agents. The use of biological agents for the treatment of sarcoidosis springs from research into the pathogenesis of the disease and also from the experience of rheumatologists with other chronic inflammatory diseases. Rituximab, golimumab and ustekinumab are cytokine modulators, useful in the treatment of immunoinflammatory disorders, for which randomized trials to evaluate safety and efficacy in sarcoidosis are not yet available. Novel anticytokine drugs administered alone or in association may offer a new approach to treatment of the disease. This review focuses on recent advances in anti-TNFα agents and cytokine modulators for the treatment of sarcoidosis and their therapeutic prospects.

Sarcoidosis induced by interferon-α in melanoma patients: incidence, clinical manifestations, and management strategies

Treatment with interferon-α has been recommended for patients with melanoma in case of micrometastases, or high risk melanoma, for example, ulcerated melanoma. Furthermore, regular dermatologic examination and regular imaging to detect recurrence or progression of disease is part of the management of melanoma patients. Sarcoidosis has been described as an adverse effect of treatment with interferon-α. Especially in hepatitis C patients, there is a series of case reports on sarcoidosis induced by interferon treatment whereas in melanoma this has rarely been reported. In a retrospective study, all melanoma patients treated with interferon-α at our hospital between 2007 and 2009 were screened for occurrence of sarcoidosis. Three of 16 melanoma patients treated with interferon-α (19%) presented with sarcoidosis. All 3 patients showed lesions with higher uptake in the positron emission tomography-computed tomography scan leading to the differential diagnosis of melanoma metastases or inflammation. Skin lesions were present in 1 patient. Diagnosis was confirmed by histologic assessment of lesions showing epithelioid granuloma-negative on Ziehl Neelson. Additional work-up included blood and urinalysis, electrocardiography, and ophthalmologic examination. Cessation of interferon-α led to regression of granulomas. Sarcoidosis induced by interferon-α in melanoma patients could be more common than previously thought. This is an important complication to be aware of as it can be mistaken for metastatic spread of melanoma and thus lead to incorrect therapy.

Inflammatory profile and response to anti-tumor necrosis factor therapy in patients with chronic pulmonary sarcoidosis

Sarcoidosis is an inflammatory, granulomatous disease of unknown etiology that most commonly afflicts the lungs. Despite aggressive immunosuppressive therapies, many sarcoidosis patients still chronically present significant symptoms. Infliximab, a therapeutic tumor necrosis factor alpha (TNF-α) monoclonal antibody (MAb), produced a small but significant improvement in forced vital capacity (FVC) in sarcoidosis patients in a double-blind, placebo-controlled, phase II clinical trial. In the current study, serum samples from this clinical trial were assessed to evaluate the underlying hypothesis that treatment with infliximab would reduce systemic inflammation associated with sarcoidosis, correlating with the extent of clinical response. A 92-analyte multiplex panel was used to assess the expression of serum proteins in 134 sarcoidosis patients compared with sera from 50 healthy controls. A strong systemic inflammatory profile was associated with sarcoidosis, with 29 analytes significantly elevated in sarcoidosis (false-discovery rate, <0.05 and >50% higher than controls). The associated analytes included chemokines, neutrophil-associated proteins, acute-phase proteins, and metabolism-associated proteins. This profile was evident despite patients receiving corticosteroids and immunosuppressive therapies. Following infliximab treatment, sarcoidosis patients expressing the highest levels of TNF-α, who had more severe disease, had the greatest improvement in FVC and reduction in serum levels of the inflammatory proteins MIP-1β and TNF-RII. This study supports the need for further exploration of anti-TNF therapy for chronic sarcoidosis patients, particularly for those expressing the highest serum levels of TNF-α.

Dysregulation of p38 and MKP-1 in response to NOD1/TLR4 stimulation in sarcoid bronchoalveolar cells

RATIONALE

Sarcoidosis is a systemic inflammatory disorder characterized by distinct up-regulation of Th1 cytokines, such as tumor necrosis factor (TNF)-α and IL-12. The mechanism underlying this up-regulation remains unclear. Recognition of microbial moieties through Toll-like or Nod-like receptors evokes sequential activation of mitogen-activated protein kinases (MAPKs), which plays a role in Th1-immune response.

OBJECTIVES

To test the hypothesis that dysregulation in MAPK signaling in response to microbial stimulation is important in mediating Th1 response in sarcoidosis.

METHODS

Ex vivo cultured bronchoalveolar lavage (BAL) cells isolated from patients with sarcoidosis and control subjects were stimulated with low-dose Toll-like receptor 4 (TLR4) and nucleotide-binding oligomerization domain 1 (NOD1) ligands as a model of microbial stimulation, and MAPK signaling and inflammatory response were analyzed.

MEASUREMENTS AND MAIN RESULTS

BAL cells from patients with sarcoidosis exhibited higher basal p38 activity, greater p38 phosphorylation, and more robust production of TNF-α and IL-12/IL-23p40 on stimulation with NOD1 and TLR4 agonists than cells isolated from control subjects. In contrast, control BAL cells had greater basal extracellular signal-regulated kinase (ERK) activity and NOD1 and TLR4 agonists preferentially activated the ERK pathway. Inhibition of p38, but not ERK, attenuated production of both IL12/IL23p40 and TNF-α. Interestingly, stimulation of cells from patients with sarcoidosis with either NOD1 or TLR4 ligand failed to induce MAPK phosphatase 1 (MKP-1). Adenovirus-mediated overexpression of MKP-1 attenuated p38 activation and decreased the production of IL12/IL23p40 and TNF-α in sarcoid BAL cells.

CONCLUSIONS

Our results suggest that enhanced p38 signaling in response to microbial products is caused by abnormal regulation of MKP-1 and contributes to heightened inflammation in sarcoidosis.

No evidence of altered alveolar macrophage polarization, but reduced expression of TLR2, in bronchoalveolar lavage cells in sarcoidosis

Background

Sarcoidosis is a granulomatous inflammatory disease, possibly of infectious aetiology. We aimed to investigate whether the degree of functional polarization of alveolar macrophages (AMs), or Toll-like receptor (TLR) expression, is associated with sarcoidosis or with distinct clinical manifestations of this disease.

Methods

Total BAL cells (cultured four or 24 h in medium, or stimulated 24 h with LPS) from 14 patients and six healthy subjects, sorted AMs from 22 patients (Löfgren's syndrome n = 11) and 11 healthy subjects, and sorted CD4+ T cells from 26 patients (Löfgren's syndrome n = 13) and seven healthy subjects, were included. Using real-time PCR, the relative gene expression of IL-10, IL-12p35, IL-12p40, IL-23p19, CCR2, CCR7, iNOS, CXCL10, CXCL11, CXCL16, CCL18, CCL20, CD80, and CD86, and innate immune receptors TLR2, TLR4, and TLR9, was quantified in sorted AMs, and for selected genes in total BAL cells, while IL-17A was quantified in T cells.

Results

We did not find evidence of a difference with regard to alveolar macrophage M1/M2 polarization between sarcoidosis patients and healthy controls. TLR2 gene expression was significantly lower in sorted AMs from patients, particular in Löfgren's patients. CCL18 gene expression in AMs was significantly higher in patients compared to controls. Additionally, the IL-17A expression was lower in Löfgren's patients' CD4+ T cells.

Conclusions

Overall, there was no evidence for alveolar macrophage polarization in sarcoidosis. However, there was a reduced TLR2 mRNA expression in patients with Löfgren's syndrome, which may be of relevance for macrophage interactions with a postulated sarcoidosis pathogen, and for the characteristics of the ensuing T cell response.

CD4+ T cells in sarcoidosis: targets and tools

Activated pulmonary T-helper type 1 lymphocytes are essential for the inflammatory process in sarcoidosis. Both the T cells and their mediators promoting inflammation may constitute possible targets for immunotherapy. A particular T-cell subset, the T-cell receptor AV2S3(+) CD4(+) T cells, are found at dramatically increased levels in the bronchoalveolar lavage fluid of a subpopulation of sarcoidosis patients with active disease. This particular T-cell subset may be used as a tool to reveal a sarcoidosis-specific antigen. Recent studies of natural killer T cells and T regulatory cells from patients with sarcoidosis have described abnormalities that may be relevant for the inflammatory process in this disease. These findings are exciting news and may be of help for designing new treatment strategies.

Safety, Tolerability, and Immunogenicity of Interferons

Interferons (IFNs) are class II cytokines that are key components of the innate immune response to virus infection. Three IFN sub-families, type I, II, and III IFNs have been identified in man, Recombinant analogues of type I IFNs, in particular IFNα2 and IFNβ1, have found wide application for the treatment of chronic viral hepatitis and remitting relapsing multiple sclerosis respectively. Type II IFN, or IFN gamma, is used principally for the treatment of chronic granulomatous disease, while the recently discovered type III IFNs, also known as IFN lambda or IL-28/29, are currently being evaluated for the treatment of chronic viral hepatitis. IFNs are in general well tolerated and the most common adverse events observed with IFNα or IFNβ therapy are “flu-like” symptoms such as fever, headache, chills, and myalgia. Prolonged treatment is associated with more serious adverse events including leucopenia, thrombocytopenia, increased hepatic transaminases, and neuropsychiatric effects. Type I IFNs bind to high-affinity cell surface receptors, composed of two transmembrane polypeptides IFNAR1 and IFNAR2, resulting in activation of the Janus kinases Jak1 and Tyk2, phosphorylation and activation of the latent cytoplasmic signal transducers and activators of transcription (STAT1) and STAT2, formation of a transcription complex together with IRF9, and activation of a specific set of genes that encode the effector molecules responsible for mediating the biological activities of type I IFNs. Systemic administration of type I IFN results in activation of IFN receptors present on essentially all types of nucleated cells, including neurons and hematopoietic stem cells, in addition to target cells. This may well explain the wide spectrum of IFN associated toxicities. Recent reports suggest that certain polymorphisms in type I IFN signaling molecules are associated with IFN-induced neutropenia and thrombocytopenia in patients with chronic hepatitis C. IFNγ binds to a cell-surface receptor composed of two transmembrane polypeptides IFGR1 and IFGR2 resulting in activation of the Janus kinases Jak1 and Jak2, phosphorylation of STAT1, formation of STAT1 homodimers, and activation of a specific set of genes that encode the effector molecules responsible for mediating its biological activity. In common with type I IFNs, IFNγ receptors are ubiquitous and a number of the genes activated by IFNγ are also activated by type I IFNs that may well account for a spectrum of toxicities similar to that associated with type I IFNs including “flu-like” symptoms, neutropenia, thrombocytopenia, and increased hepatic transaminases. Although type III IFNs share the major components of the signal transduction pathway and activate a similar set of IFN-stimulated genes (ISGs) as type I IFNs, distribution of the IFNλ receptor is restricted to certain cell types suggesting that IFNλ therapy may be associated with a reduced spectrum of toxicities relative to type I or type II IFNs. Repeated administration of recombinant IFNs can cause in a break in immune tolerance to self-antigens in some patients resulting in the production of neutralizing antibodies (NABs) to the recombinant protein homologue. Appearance of NABs is associated with reduced pharmacokinetics, pharmacodynamics, and a reduced clinical response. The lack of cross-neutralization of IFNβ by anti-IFNα NABs and vice versa, undoubtedly accounts for the apparent lack of toxicity associated with the presence of anti-IFN NABs with the exception of relatively mild infusion/injection reactions.

Dendritic cells in the pathogenesis of sarcoidosis

Sarcoidosis is a noncaseating granulomatous disease, likely of autoimmune etiology, that causes inflammation and tissue damage in multiple organs, most commonly the lung, but also skin, and lymph nodes. Reduced dendritic cell (DC) function in sarcoidosis peripheral blood compared with peripheral blood from control subjects suggests that blunted end organ cellular immunity may contribute to sarcoidosis pathogenesis. Successful treatment of sarcoidosis with tumor necrosis factor (TNF) inhibitors, which modulate DC maturation and migration, has also been reported. Together, these observations suggest that DCs may be important mediators of sarcoidosis immunology. This review focuses on the phenotype and function of DCs in the lung, skin, blood, and lymph node of patients with sarcoidosis. We conclude that DCs in end organs are phenotypically and functionally immature (anergic), while DCs in the lymph node are mature and polarize pathogenic Th1 T cells. The success of TNF inhibitors is thus likely secondary to inhibition of DC-mediated Th1 polarization in the lymph node.

Bilateral epididymal sarcoidosis

OBJECTIVE

To report a case of bilateral epididymal sarcoidosis.

DESIGN

Case report.

SETTING

University hospital.

PATIENT(S)

An azoospermic 29-year-old Caucasian male who had had an illness 2 years earlier with acute onset and progressive course of weight loss, fatigue, and cough with painless subcutaneous nodules on the arms, upper thighs, and eyelids.

INTERVENTION(S)

Physical examination, scrotal ultrasonography, scrotal magnetic resonance imaging, chest x-ray and computed tomography (CT), urine and semen Ziehl-Neelsen stain, and epididymal/testicular biopsies.

MAIN OUTCOME MEASURE(S)

Clinical, laboratory, radiologic, and histopathologic data.

RESULT(S)

The patient had bilateral epididymal firm masses with normal sized testes and bilateral enlarged, firm, nonpainful inguinal lymph nodes. Scrotal ultrasonography showed diffuse, bilateral, epididymal enlargement with heterogeneous echo pattern and increased vascularity. Scrotal magnetic resonance imaging revealed diffuse, enlarged epididymis with no focal masses. The chest x-ray revealed prominent hilar shadows, and the chest computed tomography showed mediastinal and hilar lymphadenopathy. Urine and semen Ziehl-Neelsen stains were negative for acid-fast bacilli. Epididymal histopathology revealed multiple noncaseating epithelioid granulomas with concentric arrangement of reticular fibers by reticulin stain.

CONCLUSION(S)

Scrotal involvement in sarcoidosis with its variable presentations should be considered.

Childhood sarcoidosis: A rare but fascinating disorder

Childhood sarcoidosis is a rare multisystemic granulomatous disorder of unknown etiology. In the pediatric series reported from the southeastern United States, sarcoidosis had a higher incidence among African Americans. Most reported childhood cases have occurred in patients aged 13-15 years. Macrophages bearing an increased expression of major histocompatibility class (MHC) II molecules most likely initiate the inflammatory response of sarcoidosis by presenting an unidentified antigen to CD4+ Th (helper-inducer) lymphocytes. A persistent, poorly degradable antigen driven cell-mediated immune response leads to a cytokine cascade, to granuloma formation, and eventually to fibrosis. Frequently observed immunologic features include depression of cutaneous delayed-type hypersensitivity and a heightened helper T cell type 1 (Th1) immune response at sites of disease. Circulating immune complexes, along with signs of B cell hyperactivity, may also be found. The clinical presentation can vary greatly depending upon the organs involved and age of the patient. Two distinct forms of sarcoidosis exist in children. Older children usually present with a multisystem disease similar to the adult manifestations, with frequent hilar lymphadenopathy and pulmonary infiltrations. Early-onset sarcoidosis is a unique form of the disease characterized by the triad of rash, uveitis, and arthritis in children presenting before four years of age. The diagnosis of sarcoidosis is confirmed by demonstrating a typical noncaseating granuloma on a biopsy specimen. Other granulmatous diseases should be reasonably excluded. The current therapy of choice for sarcoidosis in children with multisystem involvement is oral corticosteroids. Methotrexate given orally in low doses has been effective, safe and steroid sparing in some patients. Alternative immunosuppressive agents, such as azathioprine, cyclophosphamide, chlorambucil, and cyclosporine, have been tried in adult cases of sarcoidosis with questionable efficacy. The high toxicity profile of these agents, including an increased risk of lymphoproliferative disorders and carcinomas, has limited their use to patients with severe disease refractory to other agents. Successful steroid sparing treatment with mycophenolate mofetil was described in an adolescent with renal-limited sarcoidosis complicated by renal failure. Novel treatment strategies for sarcoidosis have been developed including the use of TNF-alpha inhibitors, such as infliximab. The long-term course and prognosis is not well established in childhood sarcoidosis, but it appears to be poorer in early-onset disease.

Markers of inflammation in sarcoidosis: blood, urine, BAL, sputum, and exhaled gas

Sarcoidosis is characterized by intense inflammation at the different sites of localization. Many different mediators, such as cytokines, chemokines, and other proteins with various functions, that participate in its complex pathogenesis have been proposed as markers of inflammation. This article examines the principal literature on these different markers analyzed in serum, bronchoalveolar lavage, expired breath, and urine. After many years of research, no single marker sufficiently sensitive and specific for diagnosis of sarcoidosis has yet been found. Greater correlation with clinical parameters is needed and proper validation.

The immunology of sarcoidosis

Sarcoidosis continues to be a disease of research interest because of its complicated immune mechanisms and elusive etiology. So far, it has been established that granulomatous inflammation in sarcoidosis is predominantly a T-helper 1 immune response mediated by a complex network of lymphocytes, macrophages, and cytokines. The cause of progression to a chronic and potentially fibrotic form is unclear but may involve loss of apoptotic mechanisms, loss of regulatory response, or a persistent antigen that cannot be cleared. Recent genomic and proteomic technology has emphasized the importance of host susceptibility and gene-environment interaction in the expression of the disease.

CREB, ATF, and AP-1 transcription factors regulate IFN-gamma secretion by human T cells in response to mycobacterial antigen

IFN-gamma production by T cells is pivotal for defense against many pathogens, and the proximal promoter of IFN-gamma, -73 to -48 bp upstream of the transcription start site, is essential for its expression. However, transcriptional regulation mechanisms through this promoter in primary human cells remain unclear. We studied the effects of cAMP response element binding protein/activating transcription factor (CREB/ATF) and AP-1 transcription factors on the proximal promoter of IFN-gamma in human T cells stimulated with Mycobacterium tuberculosis. Using EMSA, supershift assays, and promoter pulldown assays, we demonstrated that CREB, ATF-2, and c-Jun, but not cyclic AMP response element modulator, ATF-1, or c-Fos, bind to the proximal promoter of IFN-gamma upon stimulation, and coimmunoprecipitation indicated the possibility of interaction among these transcription factors. Chromatin immunoprecipitation confirmed the recruitment of these transcription factors to the IFN-gamma proximal promoter in live Ag-activated T cells. Inhibition of ATF-2 activity in T cells with a dominant-negative ATF-2 peptide or with small interfering RNA markedly reduced the expression of IFN-gamma and decreased the expression of CREB and c-Jun. These findings suggest that CREB, ATF-2, and c-Jun are recruited to the IFN-gamma proximal promoter and that they up-regulate IFN-gamma transcription in response to microbial Ag. Additionally, ATF-2 controls expression of CREB and c-Jun during T cell activation.

Pivotal Advance: Th-1 cytokines inhibit, and Th-2 cytokines promote fibrocyte differentiation

CD14+ peripheral blood monocytes can differentiate into fibroblast-like cells called fibrocytes, which are associated with and are at least partially responsible for wound healing and fibrosis in multiple organ systems. Signals regulating fibrocyte differentiation are poorly understood. In this study, we find that when added to human PBMCs cultured in serum-free medium, the profibrotic cytokines IL-4 and IL-13 promote fibrocyte differentiation without inducing fibrocyte or fibrocyte precursor proliferation. We also find that the potent, antifibrotic cytokines IFN-gamma and IL-12 inhibit fibrocyte differentiation. In our culture system, IL-1beta, IL-3, IL-6, IL-7, IL-16, GM-CSF, M-CSF, fetal liver tyrosine kinase 3, insulin growth factor 1, vascular endothelial growth factor, and TNF-alpha had no significant effect on fibrocyte differentiation. IL-4, IL-13, and IFN-gamma act directly on monocytes to regulate fibrocyte differentiation, and IL-12 acts indirectly, possibly through CD16-positive NK cells. We previously identified the plasma protein serum amyloid P (SAP) as a potent inhibitor of fibrocyte differentiation. When added together, the fibrocyte-inhibitory activity of SAP dominates the profibrocyte activities of IL-4 and IL-13. The profibrocyte activities of IL-4 and IL-13 and the fibrocyte-inhibitory activities of IFN-gamma and IL-12 counteract each other in a concentration-dependent manner. These results indicate that the complex mix of cytokines and plasma proteins present in inflammatory lesions, wounds, and fibrosis will influence fibrocyte differentiation.

Circulating levels of both Th1 and Th2 chemokines are elevated in patients with sarcoidosis

BACKGROUND

In sarcoidosis, the T helper type 1 (Th1) response tends to predominate at affected disease sites; however, whether Th1/Th2 polarization occurs in the peripheral circulation is unknown.

METHODS

Fifty-two patients with sarcoidosis and 21 healthy volunteers were investigated. The concentrations of interferon-inducible protein 10 (IP-10)/CXCL10 and thymus- and activation-regulated chemokine (TARC)/CCL17 in the serum, bronchoalveolar lavage fluid (BALF) and culture supernatant were measured by an enzyme-linked immunosorbent assay. The circulating CXCR3+ CD4+ T cells and CCR4+ CD4+ T cells were assessed by flow cytometry.

RESULTS

The CXCR3- or CCR4-positive ratios among CD4+ T cells were both higher in sarcoidosis than in healthy volunteers. The serum levels of both IP-10 and TARC of the patients with sarcoidosis were significantly higher than those of the healthy volunteers. In patients with sarcoidosis, a larger amount of IP-10 was generated by the BALF cells, whereas IP-10 production by peripheral blood mononuclear cells did not increase in comparison to the control subjects. The TARC levels produced by peripheral blood mononuclear cells of sarcoidosis patients were significantly higher than those of the controls, while no difference existed between the 2 groups regarding TARC production by BALF cells.

CONCLUSION

IP-10 is mainly produced at the lung and TARC in the peripheral circulation in sarcoidosis patients. Both IP-10 and TARC cooperatively play a role in the pathogenesis of sarcoidosis.

Current and emerging strategies for the management of sarcoidosis

Sarcoidosis is a systemic inflammatory disorder of unknown etiology. Although any organ may be involved, the lungs are most frequently affected. The clinical course of the disease is highly variable, with up to two-thirds of untreated patients experiencing spontaneous remission within 12-24 months of onset of symptoms. When therapy is required, corticosteroids are considered standard, but studies demonstrating their ability to modify the long-term outcome in this disease are lacking. Often, the myriad of adverse side effects of corticosteroids necessitate the addition of immunosuppressants, cytotoxic agents or biologic therapies to maintain disease remission. Unfortunately, optimal therapeutic regimens have not been described. Patients who do not respond to therapy often experience progressive fibrotic changes and end-organ damage, which ultimately may result in significant morbidity or death. Agents commonly used to treat patients with sarcoidosis and emerging therapeutic options are discussed.

CXCL9 and 11 in patients with pulmonary sarcoidosis: a role of alveolar macrophages

Interferon-inducible protein-10 (IP-10)/CXCL10, which is a ligand for CXC chemokine receptor 3 (CXCR3), is known to be involved in the pathogenesis of pulmonary sarcoidosis. However, the roles of monokine induced by interferon gamma (Mig)/CXCL9 and interferon-inducible T cell alpha chemoattractant (I-TAC)/CXCL11, which are also CXCR3 ligands, remain unclear. Mig/CXCL9, IP-10/CXCL10 and I-TAC/CXCL11 in both bronchoalveolar lavage fluid (BALF) and serum in patients with pulmonary sarcoidosis were measured by enzyme-linked immunosorbent assay (ELISA). The expression of these chemokines in alveolar macrophages was examined using ELISA, quantitative real-time polymerase chain reaction and immunostaining. In BALF, Mig/CXCL9 and IP-10/CXCL10 were significantly elevated in stage II sarcoidosis as compared with the levels in healthy volunteers. In serum, Mig/CXCL9 and I-TAC/CXCL11 were increased in stage II of the disease. The levels of all CXCR3 ligands in BALF were correlated with the numbers of both total and CD4(+) lymphocytes. Alveolar macrophages were stained positive for all CXCR3 ligands and produced increased amounts of these chemokines. Positive staining of the three chemokines was also observed in the epithelioid and giant cells in the sarcoid lungs. These findings suggest that Mig/CXCL9 and I-TAC/CXCL11 as well as IP-10/CXCL10 play important roles in the accumulation of Th1 lymphocytes in sarcoid lungs.

Immunopathogenesis of sarcoidosis

The immunopathogenesis of sarcoidosis has been difficult to charaterize given the heterogeneity of disease, the elusiveness of the causative antigen, and the lack of an adequate animal model. However, by examining well-defined clinical cohorts, the interplay between genetic predisposition and immunologic response has been increasingly informative. Technological advances in cellular analysis have allowed researchers to characterize the immune responses important in the maintenance of granulomatous inflammation. Finally, "new" clinical observations such as granuloma responsiveness to targeted biological therapies, sarcoid developing during immune restoration, and the relationship between sarcoidosis and Hepatitis C will provide future insight to the immunopathogenesis of sarcoidosis.

Circulating IL-12 p40 is increased in the patients with sarcoidosis, correlation with clinical markers

OBJECTIVE

Sarcoidosis is considered to be provocated by highly activated Th1 lymphocytes. Because interleukin 12 (IL-12) is one of the most important cytokines for promoting Th1 reaction, we tried to detect IL-12 and its ligand IL-12 receptor in sarcoidosis patients.

PATIENTS AND METHODS

We measured the serum concentration of IL -12 p40 and IL-12 p70 by ELISA method with serum obtained from 60 sarcoidosis patients, and compared the serum concentration of IL-12 p40 with other clinical markers of disease activity. Next, we examined mRNA production of IL-12 p35, IL-12 p40, IL-12Rbeta1, and IL-12beta2 of sarcoid lymph nodes with semi-quantitative RT-PCR method.

RESULTS

First, we showed that circulating IL-12 p40 was highly increased in sarcoidosis patients and was related to various other clinical markers. In particular, it was correlated with the number of involved organs which means systemic disease expansion. Second, we showed that the mRNA expression of IL-12 p40 and IL-12 receptor beta2 subunit was increased in sarcoid lymph nodes.

CONCLUSION

Our data suggest that increased circulating IL-12 p40 is an important systemic marker for disease activity, and it reflects the increased interaction between Il-12 and its ligand IL-12R in sarcoid lesions of involved organs.

Treatment of monocytes with interleukin (IL)-12 plus IL-18 stimulates survival, differentiation and the production of CXC chemokine ligands (CXCL)8, CXCL9 and CXCL10

During inflammation, interleukin (IL)-12 and IL-18 are produced by macrophages and other cell types such as neutrophils (IL-12), keratinocytes and damaged endothelial cells (IL-18). To explore the role of IL-12 and IL-18 in inflammatory innate immune responses we investigated their impact on human peripheral blood monocytes and mature bronchoalveolar lavage (BAL) macrophages. IL-12 and IL-18 together, but not alone, prevented spontaneous apoptosis of cultured monocytes, promoted monocyte clustering and subsequent differentiation into macrophages. These morphological changes were accompanied by increased secretion of CXC chemokine ligands (CXCL)9, CXCL10 (up to 100-fold, P < 0.001) and CXCL8 (up to 10-fold, P < 0.001) but not CCL3, CCL4 or CCL5. Mature macrophages (from BALs) expressed high basal levels of CXCL8, that were no modified upon stimulation with IL-12 and IL-18. In contrast, the basal production of CXCL9 and CXCL10 by BALs was increased by 10-fold (P < 0.001) in the presence of either IL-12 or IL-18 alone and by 50-fold in the presence of both cytokines. In conclusion, our results indicate a relevant role for IL-12 and IL-18 in the activation and resolution of inflammatory immune responses, by increasing the survival of monocytes and by inducing the production of chemokines. In particular, those that may regulate angiogenesis and promote the recruitment of monocytes, activated T cells (CXCL9 and CXCL10) and granulocytes (CXCL8).

The clinical significance of interleukin 18 assessment in sarcoidosis patients

INTRODUCTION

Sarcoidosis is a multisystemic disease of unknown etiology characterized by the formation of immune granulomas in involved organs. The cytokine profile in inflamed lesions of sarcoidosis is mainly determined by T helper 1 (Th1) cells. Interleukin 18 (IL-18) is primarily a monocyte/macrophage-derived cytokine. IL-18 has been recently identified as an IFNgamma-inducing factor. The cytokine plays an important role in the induction of Th1 response and it may be responsible for sarcoidosis progression. The aim of the study was to assess the usefulness of IL-18 estimation in the sarcoidosis diagnosis and the disease course prognosis.

MATERIAL AND METHODS

The diagnosis of sarcoidosis was established in 88 patients (the mean age of 38.1+/-10.8 years). We measured IL-18 level in plasma and bronchoalveolar lavage fluid (BALF) cell culture supernatant (CCS) using the enzyme-linked immunoassay technique (ELISA). We also performed the flow cytometric analysis of BALF lymphocyte phenotype. Statistica 5.0 and non-parametric tests: the Mann-Whitney U-test and the Spearman correlation test, were used for statistical analysis.

RESULTS

The patient group consisted of 55 subjects without acute symptoms of sarcoidosis, 14 patients with acute Löfgren syndrome and 19 subjects with Löfgren syndrome in the past. Lung hilar lymphadenopathy was diagnosed in 49 patients and lung interstitial changes in 39 subjects. After 6-month-observation, 49 patients were in remission, 20 subjects manifested persistent disease and 19 patients had sarcoidosis progression. Plasma IL-18 level was significantly (P<0.0001) higher in sarcoidosis patients (383+/-250pg/ml) than in control subjects (146+/-72pg/ml). Plasma IL-18 level was similar both in subjects with Löfgren syndrome and in other patients. However, IL-18 level in BALF CCS was significantly (P<0.05) lower in Löfgren syndrome patients than in subjects without acute manifestation of the disease. The highest IL-18 level in plasma was found in patients with disease progression, in subjects with lung interstitial changes and in patients with extrapulmonary manifestation of the disease. We observed a positive correlation between plasma IL-18 level and the percentage of BALF lymphocytes (R=0.202, P=0.06) as well as the percentage of activated HLA DR+T cells (R=0.23, P<0.05). There was a negative correlation between the IL-18 level in BALF CCS and the percentage of BALF CD3-positive and CD4-positive lymphocytes (R=-0.27, -0.23, P<0.05).

CONCLUSION

IL-18 may play a significant role in the prolongation of sarcoidosis course. Its estimation may become a good prognostic factor, which should be analyzed together with other factors useful in sarcoidosis monitoring.

Upregulation of Th1 cytokine profile (IL-12, IL-18) in bronchoalveolar lavage fluid in patients with pulmonary sarcoidosis

Sarcoidosis, a systemic granulomatous disease of unknown etiology, is characterized by a predominantly Th1 cytokine milieu, which is involved in its immunopathogenesis. The role of novel immunologic markers reflecting T cell activity of the sarcoid immunologic response needs to be determined. The present study aims to evaluate the role of the Th1 cytokine pattern by estimating the local and systemic levels of interleukin-12 (IL-12) and IL-18 in bronchoalveolar lavage fluid (BALF), induced sputum, and serum of patients with pulmonary sarcoidosis. We studied prospectively 20 patients (12 women, 8 men) of median age 46 years (range 25-65) with sarcoidosis and 10 normal subjects (5 women, 5 men) of median age 39 years (range 26-60). IL-12 and IL-18 levels were measured using ELISA kits. The IL-12 BALF levels were significantly higher in sarcoidosis patients than in healthy subjects (5.64 +/- 0.21 pg/mL vs. 5.16 +/- 0.15 pg/mL, p < 0.001). In addition, IL-18 levels were significantly increased in BALF samples (47.69 +/- 6.29 pg/mL vs. 16.73 +/- 3.00 pg/mL, p < 0.001). A statistically significant decrease in IL-12 serum levels was detected in the sarcoid population compared with controls (5.77 +/- 0.50 pg/mL vs. 7.87 +/- 2.00 pg/mL, p < 0.001). No significant differences were detected in IL-12 and IL-18 levels between patients and controls in induced sputum samples. Our data suggest a potential role of IL-12 and IL-18 in the local immunologic response in pulmonary sarcoidosis. Further large-scale studies are needed to define the precise role of IL-12 and IL-18 in the immunopathogenesis of this disorder.

Antioxidant down-regulates interleukin-18 expression in asthma

An alteration in the balance between a T-helper type 2 cell (Th2) response and a Th1 response may predispose to the development of bronchial asthma. Interleukin-18 (IL-18) has an ability to promote both Th1 and Th2 responses, depending on the surrounding cytokine environment. Reactive oxygen species (ROS) play a crucial role in the pathogenesis of airway inflammation and hyperresponsiveness. Recent studies have demonstrated that antioxidants are able to reduce airway inflammation and hyperreactivity in animal models of asthma. In this study, we used a C57BL/6 mouse model of allergic asthma to examine the effects of antioxidants on the regulation of IL-18 expression. Our present study with ovalbumin-induced murine model of asthma revealed that ROS production in cells from bronchoalveolar lavage fluids was increased and that administration of L-2-oxothiazolidine-4-carboxylic acid or alpha-lipoic acid reduced the increased levels of ROS, the increased expression of IL-18 protein and mRNA, airway inflammation, and bronchial hyperresponsiveness. Our results also showed that antioxidants down-regulated a transcription factor, nuclear factor-kappaB (NF-kappaB), activity. These results indicate that antioxidants may reduce IL-18 expression in asthma by inhibiting the activity of NF-kappaB and suggest that ROS regulate the IL-18 expression.

Sarcoidosis after treatment with interferon-alpha: a case series and review of the literature

Recombinant interferon-alpha (rINF-alpha) is an immunomodulator used in the treatment of various conditions, including viral infections and malignancies. The use of rINF-alpha has been associated with the development of sarcoidosis in recent case reports. In this series, we report the incidence of sarcoidosis in recipients of rINF-alpha for hepatitis C viral (HCV) infection at our institution. We also review the 57 additional cases of sarcoidosis associated with rINF-alpha described in the literature, including clinical presentation, radiographic findings, management, and outcomes, and discuss the potential mechanisms by which rINF-alpha may lead to the development of sarcoidosis.

CD4+ invariant T-cell-receptor+ natural killer T cells in bronchial asthma

BACKGROUND

Bronchial asthma is associated with an inflammatory process that is characterized by the presence in the airways of large numbers of CD4+ T cells producing interleukin-4 and interleukin-13. However, the CD4 antigen is expressed not only by class II major histocompatibility complex (MHC)-restricted CD4+ T cells, but also by a newly identified subgroup of T cells, CD1d-restricted natural killer T cells. These cells express a conserved (invariant) T-cell receptor and have a potent immunoregulatory function. Because mouse models of allergic asthma indicate that natural killer T cells are required for the development of allergen-induced airway hyperreactivity, we hypothesized that natural killer T cells play an important role in human asthma.

METHODS

We used CD1d-tetramers, antibodies specific for natural killer T cells, as well as reverse-transcriptase-polymerase-chain-reaction analysis of the invariant T-cell receptor of natural killer T cells to assess the frequency and distribution of natural killer T cells in the lungs and in the circulating blood of 14 patients with asthma.

RESULTS

About 60 percent of the pulmonary CD4+CD3+ cells in patients with moderate-to-severe persistent asthma were not class II MHC-restricted CD4+ T cells but, rather, natural killer T cells. The natural killer T cells expressed an invariant T-cell receptor and produced type 2 helper cytokines. In contrast, the CD4+ T cells found in the lungs of patients with sarcoidosis were conventional CD4+CD3+ T cells, not natural killer T cells.

CONCLUSIONS

Together with studies in mice indicating a requirement for natural killer T cells in the development of allergen-induced airway hyperreactivity, our results strongly suggest that CD4+ natural killer T cells play a prominent pathogenic role in human asthma.

Endotoxin Up-regulates Interleukin-18

RATIONALE AND OBJECTIVES

Sarcoidosis is a granulomatous disease of unknown etiology characterized by a helper T-cell type 1-mediated process. Previously we demonstrated a role for interleukin-18 in sarcoidosis. Here we examine the regulation of interleukin-18 in this condition.

METHODS

Cytokine levels in sarcoid epithelial lining fluid were measured by ELISA. We examined interleukin-18 promoter activity and mRNA and protein levels in the epithelial lining fluid of individuals with active sarcoidosis, and of individuals recovered from sarcoidosis, in response to purified protein derivative of Mycobacterium tuberculosis, beryllium sulfate, zirconium sulfate, aluminum sulfate, and lipopolysaccharide. Endotoxin levels in the epithelial lining fluid of individuals with sarcoidosis, individuals recovered from sarcoidosis, and control subjects were assessed by Limulus amebocyte lysate analysis. Allele-specific polymerase chain reaction was used to genotype 94 patients with sarcoidosis and 97 control subjects for the interleukin-18 -607(A/C) polymorphism. Species-specific polymerase chain reaction identified bacterial DNA in fluid samples.

RESULTS

Epithelial lining fluid from active sarcoids contained elevated levels of interleukin-18, interferon-gamma, and interleukin-12 compared with recovered patients and also contained significantly higher levels of endotoxin. Depletion of endotoxin from this epithelial lining fluid reduced its effect on the human interleukin-18 promoter in vitro. There was a higher frequency of the -607C allele and -607(C/C) genotype in the sarcoidosis population compared with control subjects; however, this was not associated with a functional response to endotoxin treatment. Finally, bacterial 16S rRNA from Haemophilus influenzae and Moraxella catarrhalis was detected in sarcoid fluid samples.

CONCLUSIONS

The pathogenesis of sarcoidosis is propagated through the actions of a helper T-cell type 1-driven response. This study shows that gram-negative bacteria may contribute to this effect by upregulating interleukin-18 expression.

Serum IL-18 levels in tuberculosis: comparison with pneumonia, lung cancer and healthy controls

OBJECTIVE

The aim of the present study was to document the serum IL-18 levels in patients with pulmonary tuberculosis (P-TB), extrapulmonary tuberculosis (EP-TB), pneumonia, lung cancer and in healthy controls, and to investigate whether it may assist in the differential diagnosis of P-TB.

METHODOLOGY

A total of 116 patients were included in the study. The study population consisted of patients with P-TB, EP-TB, pneumonia and lung cancer and controls. P-TB patients were graded according to sputum positivity and extent of disease. Serum levels of IL-18 (ELISA) were compared between groups and with other clinical measures of disease.

RESULTS

Compared with the controls, all groups of patients had increased serum levels of IL-18. The highest mean concentration of IL-18 was observed in P-TB. Serum levels of IL-18 in the patients with P-TB correlated well with the extent of disease.

CONCLUSIONS

Although increased serum levels of IL-18 were not specific for TB, the increased levels may favour active TB in radiologically advanced disease where CXR findings are difficult to interpret, and sputum smears or cultures are not helpful.

Role for CXCR6 and its ligand CXCL16 in the pathogenesis of T-cell alveolitis in sarcoidosis

RATIONALE

Receptor expression dictates the spectrum of chemokine actions on immunocompetent cells. We have previously shown that the chemokine receptor CXCR3 is highly expressed by T-helper type 1 (Th1) cells infiltrating the lungs of patients with sarcoidosis.

OBJECTIVES

The evaluation of the role of Bonzo/CXCR6 and its ligand CXCL16 in the pathogenesis of sarcoidosis.

METHODS

Immunocompetent cells infiltrating sarcoid lung have been evaluated by flow cytometry, confocal microscopy, immunohistochemical and molecular analysis, and functional assays.

MAIN RESULTS

Th1 cells isolated from the bronchoalveolar lavage of patients with sarcoidosis and T-cell alveolitis coexpressed CXCR3 and CXCR6. Immunohistochemical analysis of lung specimens has shown that CXCR6+ T cells infiltrated lung interstitium surrounding the central core of the granuloma. The CXCR6 ligand CXCL16 was abundantly expressed by macrophages infiltrating sarcoid tissue and/or forming the granuloma core. From a functional point of view, sarcoid Th1 cells were able to respond to CXCL10 and CXCL16 in migratory assay. In vitro kinetic studies demonstrated that, although CXCR3 was rapidly induced by interleukin (IL)-15 and IL-18, CXCR6 induction was slow (8 d) and mainly regulated by IL-15.

CONCLUSIONS

T cells coexpressing CXCR3 and CXCR6 act coordinately with respective ligands and Th1 inflammatory cytokines in the alveolitic/granuloma phases of the disease.

Interleukin-18 bioactivity: a novel target for immunopharmacological anti-inflammatory intervention

Interleukin-18 is a member of the interleukin-1 family of cytokines with pro-inflammatory and tumor-suppressive properties. Its ability to potently enhance the production of interferon-gamma indicates in particular the crucial function of interleukin-18 as an immunomodulatory molecule. In fact, high levels of interleukin-18 are detected in human diseases associated with immunoactivation including viral or bacterial infections and chronic inflammation. Animal models suggest suppression of interleukin-18 bioactivity as a novel therapeutic concept specifically for the treatment of chronic inflammatory diseases such as rheumatoid arthritis, Crohn's disease, and psoriasis. Here we introduce into the biology of interleukin-18 and review immunopharmacological strategies that aim at reducing interleukin-18 bioactivity in human disease.

[Update on sarcoidosis]

Since the first description more than a century ago, intensive research continues to focus on sarcoidosis. Based on our current knowledge, sarcoidosis can be considered as an immune syndrome resulting from a variable combination of predisposing genetic, ethnic, and environmental factors. Over the last few years, several teams have proposed a link between certain genetic polymorphisms, particularly of the HLA system, and the risk of development or progression of sarcoidosis. Other pathogenic mechanisms involved in the formation of the sarcoid granuloma are becoming more clear and have led to the development of new therapeutic approaches such as anti-TNF currently being evaluated in multicentric trials.

Asymptomatic systemic sarcoidosis arising 5 years after IFN-alpha treatment for chronic hepatitis C: a new challenge for clinicians

Interferon (IFN)-induced sarcoidosis is well documented. Herein, we report the case of a patient with chronic hepatitis C (CHC) who developed IFN-alpha-induced sarcoidosis. The clinical features of this case make it unique among all cases so far described. The patient was, in fact, asymptomatic for sarcoidosis, and the disease, characterized by liver and lung granulomatosis, was discovered by chance during the CHC follow-up. The diagnosis was made 5 years after IFN-alpha discontinuation. A pathogenetic role for IFN-alpha in our patient is supported by a liver biopsy performed before the therapy with IFN-alpha was started, showing no evidence of granulomatous localizations. This case suggests that the incidence of sarcoidosis during IFN-alpha treatment is underestimated. A search for clinical and laboratory findings typical of the disease, as well as a liver biopsy, should always be included in the follow-up of CHC patients undergoing therapy with IFN-alpha.

Deficiency of a subset of T-cells with immunoregulatory properties in sarcoidosis

BACKGROUND

Sarcoidosis is a multisystem disorder that predominantly involves the lungs, characterised by a T-helper 1 (Th1) biased CD4-positive T-cell response and granuloma formation, for which the explanation is unknown. A newly identified subset of T-cells with immunoregulatory functions, CD1d-restricted natural-killer T (NKT) cells, has been shown to protect against disorders with increased CD4-positive Th1 responses in animals. We explored whether abnormalities in these cells are implicated in the pathogenesis of sarcoidosis.

METHODS

We generated fluorescence-labelled CD1d-tetrameric complexes and used them, with monoclonal antibodies to Valpha24 and Vbeta11 T-cell receptor, to assess the frequency of CD1d-restricted NKT cells in the peripheral blood of 60 patients with histologically proven sarcoidosis (16 with Lofgren's syndrome) and 60 healthy controls. Lung lymphocytes were also analysed in 16 of the patients with sarcoidosis.

FINDINGS

CD1d-restricted NKT cells were absent or greatly reduced in peripheral blood from all patients with sarcoidosis, except those with Lofgren's syndrome (median proportion of lymphocytes 0.01% [IQR 0-0.03] vs 0.06% [0.03-0.12] in controls; p=0.0004). The deficiency was found in both acute and resolved disease and was unrelated to systemic corticosteroid therapy. There was no difference in the proportion of CD1d-restricted NKT cells between peripheral blood and lungs in patients, suggesting that the peripheral-blood deficiency is not due to sequestration of these cells in the lungs. The NKT cells were not observed in mediastinal lymph nodes or granulomatous lesions. CD1d expression on antigen-presenting cells of patients was normal, thus the deficiency of CD1d-restricted NKT cells is not explained by abnormal CD1d expression.

INTERPRETATION

Loss of immunoregulation by CD1d-restricted NKT cells could explain the amplified and persistent T-cell activity that characterises sarcoidosis.

RELEVANCE TO PRACTICE

Our findings give new insight into the pathogenesis of sarcoidosis and draw attention to a potential target for therapeutic modulation in sarcoidosis.

Evaluation of microsatellite markers in association studies: a search for an immune-related susceptibility gene in sarcoidosis

Association studies using linkage disequilibrium (LD) between candidate loci and nearby markers have been proposed to identify susceptibility genes for complex diseases. We analyzed polymorphisms of microsatellites (MSs) and LD patterns of the regions in which candidate genes related to the Th1 immune response have been annotated and attempted to identify a susceptibility gene for sarcoidosis in a marker-based association study. Nineteen MSs were identified in six Th1-related genes (IFNGR1, IFNGR2, IL12RB1, IL12RB2, STAT1 and STAT4) and then eight were further characterized as useful polymorphic markers. Most of these MSs showed LD with single nucleotide polymorphisms (SNPs) on both 5' and 3' ends of these candidate genes, in which r(2) values between at least one of the MS marker alleles and the SNPs were higher than 0.1. A significant association with one MS allele near STAT4 was shown and a cluster of SNPs in LD with the MS marker was associated with sarcoidosis. These results suggest that association studies using not only SNPs but also multi-allelic MS within or near candidate loci would be useful markers to search for a disease susceptibility gene, especially in populations with unknown LD structure.

No association between interleukin-18 gene polymorphisms and haplotypes in Dutch sarcoidosis patients

Previously, an association between susceptibility to sarcoidosis and a polymorphism in the interleukin (IL-18) gene (IL-18 -607A/C) has been reported in Japanese. The aim of the present study was to validate this association in a clinically well-characterized population of Dutch Caucasians. Three other polymorphisms at positions -656, -137, and 1248 were included in order to extend the mapping of the IL-18 gene and to enable the construction of haplotypes. Polymorphisms were determined using sequence-specific primers (SSPs) and polymerase chain reaction (PCR). A total of 236 individuals was studied (133 patients and 103 controls). No significant differences were observed in the distribution of the -607 and the other polymorphisms between Dutch sarcoidosis patients and controls. However, significant differences in IL-18 -607 genotype and allele frequency distributions were found between the Dutch and the Japanese. From the investigated IL-18-promoter polymorphisms, we were able to deduce four haplotypes. No differences were observed in haplotype frequencies between Dutch sarcoidosis patients and controls. In conclusion, IL-18 polymorphisms do not appear to influence the susceptibility to sarcoidosis in Dutch Caucasians. Important differences in allele frequencies were observed between Japanese and Dutch sarcoidosis patients and controls.

Granulomatous diseases of the oral tissues: differential diagnosis and update

Because of the relatively nonspecific clinical findings associated with a variety of granulomatous diseases, a microscopic diagnosis of granulomatous inflammation often presents a diagnostic dilemma for the clinician. The most common differential diagnosis includes foreign body reactions, infection, Crohn's disease, sarcoidosis, and orofacial granulomatosis. However, a variety of other conditions may be associated with granuloma formation. Often an extensive clinical, microscopic, and laboratory evaluation may be required to identify the source of the granulomatous inflammation. This article highlights the origin, clinical manifestations, current diagnostic modalities, and treatment of specific granulomatous diseases that may be encountered in clinical practice.

Interleukin-18 levels in induced sputum are reduced in asthmatic and normal smokers

BACKGROUND

IL-18 is a cytokine which is known to have an important role in the development of a Th1 lymphocyte response. As such, it may have a regulatory role in asthma by modifying Th2 lymphocyte responses. Cigarette smoking may amplify the airway inflammation associated with asthma.

OBJECTIVE

This study investigated if IL-18 could be detected in induced sputum from asthmatics and normal subjects and if smoking altered IL-18 levels.

METHODS

Induced sputum was obtained from asthmatic (31 smokers, 35 non-smokers) and normal (20 smokers, 20 non-smokers) subjects. All smokers had a smoking history of > or =15 pack years. IL-18 levels in sputum supernatant were measured by ELISA. IL-18 mRNA expression and cellular localization were assessed by quantitative PCR and immunocytochemistry, respectively.

RESULTS

Smoking was associated with a significant reduction in IL-18 levels (median (interquartile range) - smokers 20 (0-102) pg/mL vs. non-smokers 358 (50-876) pg/mL, P<0.001). This was more pronounced in asthmatics (smokers, 47 (40-64) pg/mL vs. non-smokers, 530 (30-1484) pg/mL; P<0.001) than in normal subjects (smokers, 25 (0-78) pg/mL vs. non-smokers, 247 (50-656) pg/mL; P<0.01). Within each of the smoking and non-smoking groups there was no significant difference in IL-18 levels between asthmatic and normal subjects. There was no correlation between sputum IL-18 levels and any specific cell type in the sputum samples nor serum IgE levels. IL-18 mRNA expression was reduced in asthmatic smokers compared with non-smokers. IL-18 production was localized to sputum macrophages by immunocytochemistry.

CONCLUSIONS

IL-18 is detectable in induced sputum samples from both asthmatic and normal subjects. Cigarette smoking significantly reduces sputum IL-18 levels. This effect is more pronounced in asthmatics than in normal subjects.

Clinical and immunologic components of sarcoidosis

Sarcoidosis is a multisystem granulomatous disease of unknown etiology that affects the lungs and the lymphatic system. It is seen by specialists in allergy, rheumatology, and pulmonary disease. Although there are no clues to etiology, an environmental basis has been implicated primarily on the basis of epidemiologic and anecdotal data. The majority of patients are very readily diagnosed and should not be confused with other pulmonary disorders. Sarcoidosis can become an issue if it occurs in the presence of other significant pulmonary disease, such as patients with asthma or hypersensitivity pneumonitis. Most patients remain asymptomatic and many are diagnosed when picked up on a routine screening exam. Steroids can be used to manage some patients but caution should be exercised to choose the appropriate dose and to treat patients for a limited period of time to avoid the complications of steroids. A minority of patients do progress to significant disease, including morbidity and mortality, and further research is needed to determine more appropriate and specific therapy for such situations.