Cellular and molecular aspects of granulomatous inflammation

Oral Granulomatous Disorders: A Diagnostic Insight

Granulomatous inflammation represents a unique pattern of chronic inflammation observed in a restricted form of infectious and certain non-infectious diseases. The formation of granulomas typically involves immune responses. Granulomatous disorders encompass a broad spectrum of conditions that share the common histological feature of granuloma formation. Their involvement in the oral soft and hard tissues is quite infrequent; however, their manifestation can pose a diagnostic challenge due to the diverse range of potential causes and the relatively non-specific appearance of the individual lesions. The ultimate outcome of a complex entails the formation of a granuloma, resulting from the interplay among an invading pathogen or antigen, chemical substance, medication, or other irritant, persistent presence of antigens in the bloodstream, activation of macrophages, initiation of Th1 cell response, B-cell overactivity, presence of circulating immune complexes, and a wide range of biological signaling molecules, ultimately leading to the development of fibrosis attributed to the actions of transforming and platelet-derived growth factor. This article emphasizes the clinicopathological diagnostic criteria of oral granulomatous disorders as a guide for treatment and management.

Different Molecular Features of Epithelioid and Giant Cells in Foreign Body Reaction Identified by Single-Cell RNA Sequencing

Although macrophage‒epithelioid cell (EPC)‒giant cell (GC) differentiation is acknowledged in foreign body reaction (FBR), the exact molecular features remain elusive. To discover the molecular profiles of EPC and GC, we analyzed mouse sponge and silk FBRs by integrating single-cell RNA sequencing and spatial sequencing, which identified seven cell types, including macrophages and fibroblasts. Macrophages comprised three subsets with a trajectory from M2-like cell to EPC to GC. They were different in many aspects, including cytokine, extracellular matrix organization/degradation, epithelial modules, and glycolysis that were consistent in both sponge and silk FBRs. EPCs exhibited epithelial modules and extracellular matrix organization, and GCs showed glycolysis, extracellular matrix degradation, and cell fusion signatures. Cellular interactions in GCs and M2-like cells were predicted to be higher than that in EPCs. High expression of inflammation or fusion-related (GPNMB, matrix metalloproteinase 12 gene MMP12, DCSTAMP) and glycolysis-related (PGAM1, ALDOA) genes was identified in GCs of human/mouse tissues, suggesting them as GC-specific markers. Our study identified unique signatures of EPCs and GCs in FBR. Importantly, GCs showed strong glycolysis signatures and cellular interactions, suggesting their activation in FBR. Our data on EPC and GC refinement and GC-specific markers enable the understanding of FBR and help to explore preventive and therapeutic management strategies for skin FBRs.

Tuberculous Granuloma: Emerging Insights From Proteomics and Metabolomics

Mycobacterium tuberculosis infection, which claims hundreds of thousands of lives each year, is typically characterized by the formation of tuberculous granulomas — the histopathological hallmark of tuberculosis (TB). Our knowledge of granulomas, which comprise a biologically diverse body of pro- and anti-inflammatory cells from the host immune responses, is based mainly upon examination of lungs, in both human and animal studies, but little on their counterparts from other organs of the TB patient such as the brain. The biological heterogeneity of TB granulomas has led to their diverse, relatively uncoordinated, categorization, which is summarized here. However, there is a pressing need to elucidate more fully the phenotype of the granulomas from infected patients. Newly emerging studies at the protein (proteomics) and metabolite (metabolomics) levels have the potential to achieve this. In this review we summarize the diverse nature of TB granulomas based upon the literature, and amplify these accounts by reporting on the relatively few, emerging proteomics and metabolomics studies on TB granulomas. Metabolites (for example, trimethylamine-oxide) and proteins (such as the peptide PKAp) associated with TB granulomas, and knowledge of their localizations, help us to understand the resultant phenotype. Nevertheless, more multidisciplinary ‘omics studies, especially in human subjects, are required to contribute toward ushering in a new era of understanding of TB granulomas – both at the site of infection, and on a systemic level.

TNF-α inhibitors used as steroid-sparing maintenance monotherapy in parenchymal CNS sarcoidosis

OBJECTIVE

To assess the efficacy of tumour necrosis factor-α (TNF-α) inhibitors used as steroid-sparing monotherapy in central nervous system (CNS) parenchymal sarcoidosis.

METHODS

The French Multiple Sclerosis and Neuroinflammation Centers retrospectively identified patients with definite or probable CNS sarcoidosis treated with TNF-α inhibitors as steroid-sparing monotherapy. Only patients with CNS parenchymal involvement demonstrated by MRI and imaging follow-up were included. The primary outcome was the minimum dose of steroids reached that was not associated with clinical or imaging worsening during a minimum of 3 months after dosing change.

RESULTS

Of the identified 38 patients with CNS sarcoidosis treated with TNF-α inhibitors, 23 fulfilled all criteria (13 females). Treatments were infliximab (n=22) or adalimumab (n=1) for a median (IQR) of 24 (17-40) months. At treatment initiation, the mean (SD) age was 41.5 (10.5) years and median (IQR) disease duration 22 (14-49.5) months. Overall, 60% of patients received other immunosuppressive agents before a TNF-α inhibitor. The mean (SD) minimum dose of steroids was 31.5 (33) mg before TNF-α inhibitor initiation and 6.5 (5.5) mg after (p=0.001). In all, 65% of patients achieved steroids dosing <6 mg/day; 61% showed clinical improvement, 30% stability and 9% disease worsening. Imaging revealed improvement in 74% of patients and stability in 26%.

CONCLUSION

TNF-α inhibitors can greatly reduce steroids dosing in patients with CNS parenchymal sarcoidosis, even refractory.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that TNF-α inhibitor used as steroid-sparing monotherapy is effective for patients with CNS parenchymal sarcoidosis.

The Clinical Features of Patients with Sarcoidosis and Malignant Diseases in Japan

Objective Recent studies suggest a significant association between sarcoidosis and malignancy, although the results have remained controversial. The aim of this study is to evaluate the clinical features of patients with sarcoidosis associated with malignant diseases in Japan. Patients We conducted a medical record review of all sarcoidosis patients in Tohoku University Hospital between January 1, 1981, and May 31, 2017. Methods The clinical records and pathology reports for each patient were screened, and the clinical characteristics of malignancies as well as sarcoidosis were reviewed. Results A total of 52 (18.8%) patients with malignancy were identified among 277 patients with sarcoidosis. Among those 52 patients, we identified 62 with malignant diseases. These patients were older and more likely to be women than the remaining 225 (81.2%) sarcoidosis patients without malignancy. The most prevalent malignant disease was breast cancer (14 cases, 22.6%), followed by stomach cancer (8 cases, 12.9%) and lung cancer (7 cases, 11.3%). Among the 14 patients with both sarcoidosis and breast cancer, 8 (57.1%) were diagnosed with breast cancer before sarcoidosis. All of these eight cases had undergone surgical resection of the cancer. Conclusion This study showed a higher incidence of patients with both sarcoidosis and malignancy in Japan than in some western countries. Breast cancer is the most prevalent malignant disease. The high frequency of sarcoidosis after surgical resection of breast cancer may suggest a causative association between malignancy and the development of sarcoidosis.

Higher incidence of manipulation under anesthesia following TKA associated with the periarticular infiltration of a liposomal bupivacaine cocktail compared to a modified Ranawat cocktail

BACKGROUND

The purpose of this study was to compare the frequency of postoperative stiffness requiring manipulation under anesthesia (MUA) before and after switching from the intraoperative use of liposomal bupivacaine (LB).

METHODS

This was an institutional review board (IRB)-exempt retrospective cohort study (IRB#71733) on all patients who underwent primary total knee arthroplasty (TKA) by a single surgeon between April 2016 and December 2017. We compared 169 knees that received LB group to 167 knees that received a modified Ranawat cocktail (MR group). Perioperative care pathways remained consistent during the study period, as were requirements for MUA which included flexion range of motion below approximately 90 at 6-12 weeks. To compare the incidence of MUA between the groups, a population-averaged Poisson regression analysis was used.

RESULTS

The two groups were similar, with mean age of 63 (range 31-91) in the LB group and 64 (range 42-84) in the MR group, a preponderance of females in both groups (p = 0.866), similar preoperative knee flexion between groups (p = 0.162), and similar Patient-Reported Outcomes Measurement Information System scores. The frequency of MUA, however, was significantly lower in the MR group (LB: 7.7% [95% CI 3.7-12%] vs. MR: 2.4% [95% CI <1-4.7%] [IRR 3.2, 95% CI 1.08-9.76, p . 0.037]).

CONCLUSIONS

In summary, this is a novel report of a potentially previously unrecognized increased incidence of MUA associated with the use of LB compared with a MR cocktail. Given no other notable changes to the perioperative care or MUA thresholds following TKA, the reasons for these findings are unclear but deserve additional investigation.

Teleost contributions to the understanding of mycobacterial diseases

Few pathogens have shaped human medicine as the mycobacteria. From understanding biological phenomena driving disease spread, to mechanisms of host-pathogen interactions and antibiotic resistance, the Mycobacterium genus continues to challenge and offer insights into the basis of health and disease. Teleost fish models of mycobacterial infections have progressed significantly over the past three decades, now supplying a range of unique tools and new opportunities to define the strategies employed by these Gram-positive bacteria to overcome host defenses, as well as those host antimicrobial pathways that can be used to limit its growth and spread. Herein, we take a comparative perspective and provide an update on the contributions of teleost models to our understanding of mycobacterial diseases.

A Role for CD154, the CD40 Ligand, in Granulomatous Inflammation

Granulomatous inflammation is a distinctive form of chronic inflammation in which predominant cells include macrophages, epithelioid cells, and multinucleated giant cells. Mechanisms regulating granulomatous inflammation remain ill-understood. CD154, the ligand of CD40, is a key mediator of inflammation. CD154 confers a proinflammatory phenotype to macrophages and controls several macrophagic functions. Here, we studied the contribution of CD154 in a mouse model of toxic liver injury with carbon tetrachloride and a model of absorbable suture graft. In both models, granulomas are triggered in response to endogenous persistent liver calcified necrotic lesions or by grafted sutures. CD154-deficient mice showed delayed clearance of carbon tetrachloride-induced liver calcified necrotic lesions and impaired progression of suture-induced granuloma. In vitro, CD154 stimulated phagocytosis of opsonized erythrocytes by macrophages, suggesting a potential mechanism for the altered granulomatous inflammation in CD154KO mice. These results suggest that CD154 may contribute to the natural history of granulomatous inflammation.

Histopathologic review of granulomatous inflammation

Granulomatous inflammation is a histologic pattern of tissue reaction which appears following cell injury. Granulomatous inflammation is caused by a variety of conditions including infection, autoimmune, toxic, allergic, drug, and neoplastic conditions. The tissue reaction pattern narrows the pathologic and clinical differential diagnosis and subsequent clinical management. Common reaction patterns include necrotizing granulomas, non necrotizing granulomas, suppurative granulomas, diffuse granulomatous inflammation, and foreign body giant cell reaction. Prototypical examples of necrotizing granulomas are seen with mycobacterial infections and non-necrotizing granulomas with sarcoidosis. However, broad differential diagnoses exist within each category. Using a pattern based algorithmic approach, identification of the etiology becomes apparent when taken with clinical context. The pulmonary system is one of the most commonly affected sites to encounter granulomatous inflammation. Infectious causes of granuloma are most prevalent with mycobacteria and dimorphic fungi leading the differential diagnoses. Unlike the lung, skin can be affected by several routes, including direct inoculation, endogenous sources, and hematogenous spread. This broad basis of involvement introduces a variety of infectious agents, which can present as necrotizing or non-necrotizing granulomatous inflammation. Non-infectious etiologies require a thorough clinicopathologic review to narrow the scope of the pathogenesis which include: foreign body reaction, autoimmune, neoplastic, and drug related etiologies. Granulomatous inflammation of the kidney, often referred to as granulomatous interstitial nephritis (GIN) is unlike organ systems such as the skin or lungs. The differential diagnosis of GIN is more frequently due to drugs and sarcoidosis as compared to infections (fungal and mycobacterial). Herein we discuss the pathogenesis and histologic patterns seen in a variety of organ systems and clinical conditions.

Mechanisms of Granulomatous Lung Disease from Inhaled Beryllium: The Role of Antigenicity in Granuloma Formation

Granulomatous lung disease is a debilitating and sometimes fatal condition encountered in humans, for which the cellular and molecular mechanisms are poorly understood. Two patterns of granulomatous lung disease are recognized; foreign-body reactions and immune-mediated granulomas. Beryllium inhalation by humans results, in a small number of exposed individuals, in a chronic, granulomatous, immune-mediated pulmonary disease (chronic beryllium lung disease, CBD). Animal models used to study CBD have demonstrated significant species differences in the pathologic response to beryllium. While rats exposed to beryllium appear to develop a chronic, foreign-body response within the lung, dogs so exposed develop beryllium-specific immune responses within the lung and blood, accompanied by immune granulomas within the lung. At the heart of this difference appears to be the ability of the dog, but not the rat, to immunologically recognize the antigenicity of beryllium. This important difference further underscores the need to understand the mechanistic differences among similar disease syndromes, particularly if therapeutic regimens are to be used.

Reduced expression of monocyte CD200R is associated with enhanced proinflammatory cytokine production in sarcoidosis

In sarcoidosis, the proinflammatory cytokines interferon gamma, tumour necrosis factor and interleukin-6 are released by monocyte-derived macrophages and lymphocytes in the lungs and other affected tissues. Regulatory receptors expressed on monocytes and macrophages act to suppress cytokine production, and reduced expression of regulatory receptors may thus promote tissue inflammation. The aim of this study was to characterise the role of regulatory receptors on blood monocytes in patients with sarcoidosis. Cytokine release in response to stimulation of whole blood was measured in healthy controls and Caucasian non-smoking patients with sarcoidosis who were not taking disease modifying therapy. Expression of the regulatory molecules IL-10R, SIRP-α/β, CD47, CD200R, and CD200L was measured by flow cytometry, and functional activity was assessed using blocking antibodies. Stimulated whole blood and monocytes from patients with sarcoidosis produced more TNF and IL-6 compared with healthy controls. 52.9% of sarcoidosis patients had monocytes characterised by low expression of CD200R, compared with 11.7% of controls (p < 0.0001). Patients with low monocyte CD200R expression produced higher levels of proinflammatory cytokines. In functional studies, blocking the CD200 axis increased production of TNF and IL-6. Reduced expression of CD200R on monocytes may be a mechanism contributing to monocyte and macrophage hyper-activation in sarcoidosis.

CD11b+Ly6G- myeloid cells mediate mechanical inflammatory pain hypersensitivity

Pain hypersensitivity at the site of inflammation as a result of chronic immune diseases, pathogenic infection, and tissue injury is a common medical condition. However, the specific contributions of the innate and adaptive immune system to the generation of pain during inflammation have not been systematically elucidated. We therefore set out to characterize the cellular and molecular immune response in two widely used preclinical models of inflammatory pain: (i) intraplantar injection of complete Freund's adjuvant (CFA) as a model of adjuvant- and pathogen-based inflammation and (ii) a plantar incisional wound as a model of tissue injury-based inflammation. Our findings reveal differences in temporal patterns of immune cell recruitment and activation states, cytokine production, and pain in these two models, with CFA causing a nonresolving granulomatous inflammatory response whereas tissue incision induced resolving immune and pain responses. These findings highlight the significant differences and potential clinical relevance of the incisional wound model compared with the CFA model. By using various cell-depletion strategies, we find that, whereas lymphocyte antigen 6 complex locus G (Ly)6G(+)CD11b(+) neutrophils and T-cell receptor (TCR) β(+) T cells do not contribute to the development of thermal or mechanical pain hypersensitivity in either model, proliferating CD11b(+)Ly6G(-) myeloid cells were necessary for mechanical hypersensitivity during incisional pain, and, to a lesser extent, CFA-induced inflammation. However, inflammatory (CCR2(+)Ly6C(hi)) monocytes were not responsible for these effects. The finding that a population of proliferating CD11b(+)Ly6G(-) myeloid cells contribute to mechanical inflammatory pain provides a potential cellular target for its treatment in wound inflammation.

Association of serum TNF-α, IL-8 and free light chain with HLA-DR B alleles expression in pulmonary and extra-pulmonary sarcoidosis

Background

Sarcoidosis is a systemic disease of unknown etiology characterized histologically by the observation of non-caseating granulomas and several immunological abnormalities. Sarcoidosis is a multi-organ disorder which involves formation of granulomas in many tissues including the lungs (pulmonary) and others such as skin, bone, heart (extra pulmonary). Associations between human leukocyte antigens (HLA), the encoded cell surface receptor (HLA-DR) and sarcoidosis have been reported in several studies. Several HLA-DR alleles have been described as potential risk factors for sarcoidosis in distinct ethnic groups however evidence for a relationship between HLA-DR alleles and pulmonary and extra-pulmonary sarcoidosis (EPS) is still scarce. Although the etiology of the disease remains unclear, infectious and environmental factors have been postulated. Inflammatory cytokines and chemokines may play important roles in the pathogenesis of sarcoidosis and serum free light chain (FLC) numbers have been implicated in several immunologic disorders.

Purpose of the study

The aim of the present study was to investigate HLA associations with serum cytokines and FLC in Iranian patients with pulmonary (n = 86) and EPS (n = 46).

Results

We found that among the 16 HLA DRB alleles only *7 and *12 were different in sarcoidosis patients. The levels of TNF-α and IL-8 in pulmonary sarcoidosis patients were higher than in EPS (P < 0.05) whereas the levels of FLC subunits in EPS were higher than in pulmonary sarcoidosis.

Conclusion

This data may suggests a link between HLA-DRB *12 and sarcoidosis in Iranian population.

Development of vizantin, a safe immunostimulant, based on the structure-activity relationship of trehalose-6,6'-dicorynomycolate

Vizantin, 6,6'-bis-O-(3-nonyldodecanoyl)-α,α'-trehalose, was developed as a safe immunostimulator on the basis of a structure-activity relationship (SAR) study with trehalose 6,6'-dicorynomycolate (TDCM). It was possible to synthesize vizantin on a large scale more easily than in the case of TDCM, and the compound exhibited more potent prophylactic effect on experimental lung metastasis of B16-F0 melanoma cells. Because vizantin stimulated human macrophages, it is a promising candidate for clinical application.

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.

Dramatic response to infliximab in refractory neurosarcoidosis

Sarcoidosis is a systemic disease characterized by noncaseating granulomas in the involved organs. Neurologic manifestations involving the central and/or peripheral nervous system occur in about 5% of patients. Neurosarcoidosis is often refractory to conventional treatment and therefore more effective treatment options are needed. While the etiology of the disease is still unknown, there is now a better understanding of its pathogenesis on a molecular level. It is clear that tumor necrosis factor-α (TNFα) plays a pivotal role in the development of the granulomas and it is believed to be a key cytokine involved in the pathogenesis of the disease. Taking advantage of this better understanding of disease pathogenesis, anti-TNFα agents are being increasingly used to treat refractory sarcoidosis. We report a patient with refractory neurosarcoidosis who showed dramatic improvement in the clinical and radiological manifestations following treatment with infliximab; he suffered a relapse upon discontinuation of the medication.

Risk factors for high mesothelial cell counts in HIV-negative patients with tuberculous pleural effusion

BACKGROUND/PURPOSE

Higher mesothelial cell counts (HM) greater than 5% of total cell counts in tuberculous pleural effusions (TBPE) have been described in human immunodeficiency virus (HIV)-infected patients, however the nature and risk factors in HIV-negative patients with TBPE are unknown. The purpose of the study was to characterize the clinical manifestation of HM in HIV-negative patients with TBPE and evaluate the risk factors of developing HM-TBPE.

METHODS

This retrospective study was undertaken in HIV-negative patients with TBPE from the Far Eastern Memorial Hospital Tuberculosis database. The cytologist and examining specialist differentiated and quantified the cell counts. HM-TBPE was defined when more than 5% of total cell counts in the pleural fluid were mesothelial cells. Multivariate analysis was calculated with stepwise logistic regression for HM-TBPE risk factors.

RESULTS

Nineteen patients were diagnosed as HM-TBPE, while 30 were diagnosed with lower mesothelial cell counts TBPE (LM-TBPE). Compared with LM-TBPE patients, those with HM-TBPE had significantly decreased hemoglobin and serum albumin levels (p<0.05). Organ dysfunction such as congestive heart failure, liver cirrhosis and renal failure was significantly more common in patients with HM-TBPE (47.4%) than in patients with LM-TBPE (13.3%; p=0.01). Multivariate analysis revealed that independent risk factors for developing HM-TBPE included hypoalbuminemia (odds ratio =1.6; 95% confidence interval = 1.1-13.8) and the presence of organ dysfunction (odds ratio =4.5; 95% confidence interval = 1.4-17.5).

CONCLUSION

Baseline hypoalbuminemia and comorbidities were independent risk factors for development of HM-TBPE in HIV-negative patients. Mesothelial cell counts should not be used alone in the diagnosis of TBPE. An understanding of the organ dysfunction associated with HM-TBPE in HIV-negative patients could avoid delayed diagnosis and treatment of tuberculosis.

High-mobility group box-1 protein promotes granulomatous nephritis in adenine-induced nephropathy

Granulomatous nephritis can be triggered by diverse factors and results in kidney failure. However, despite accumulating data about granulomatous inflammation, pathogenetic mechanisms in nephritis remain unclear. The DNA-binding high-mobility group box-1 protein (HMGB1) initiates and propagates inflammation when released by activated macrophages, and functions as an 'alarm cytokine' signaling tissue damage. In this study, we showed elevated HMGB1 expression in renal granulomas in rats with crystal-induced granulomatous nephritis caused by feeding an adenine-rich diet. HMGB1 levels were also raised in urine and serum, as well as in monocyte chemoattractant protein-1 (MCP-1), a mediator of granulomatous inflammation. Injection of HMGB1 worsened renal function and upregulated MCP-1 in rats with crystal-induced granulomatous nephritis. HMGB1 also induced MCP-1 secretion through mitogen-activated protein kinase (MAPK) and phosphoinositide-3-kinase (PI3K) pathways in rat renal tubular epithelial cells in vitro. Hmgb1(+/-) mice with crystal-induced nephritis displayed reduced MCP-1 expression in the kidneys and in urine and the number of macrophages in the kidneys was significantly decreased. We conclude that HMGB1 is a new mediator involved in crystal-induced nephritis that amplifies granulomatous inflammation in a cycle where MCP-1 attracts activated macrophages, resulting in excessive and sustained HMGB1 release. HMGB1 could be a novel target for inhibiting chronic granulomatous diseases.

Development of a sarcoidosis murine lung granuloma model using Mycobacterium superoxide dismutase A peptide

Sarcoidosis is characterized by noncaseating granulomas containing CD4(+) T cells with a Th1 immunophenotype. Although the causative antigens remain unknown, independent studies noted molecular and immunologic evidence of mycobacterial virulence factors in sarcoidosis specimens. A major limiting factor in discovering new insights into the pathogenesis of sarcoidosis is the lack of an animal model. Using a distinct superoxide dismutase A peptide (sodA) associated with sarcoidosis granulomas, we developed a pulmonary model of sarcoidosis granulomatous inflammation. Mice were sensitized by a subcutaneous injection of sodA, incorporated in incomplete Freund's adjuvant (IFA). Control subjects consisted of mice with no sensitization (ConNS), sensitized with IFA only (ConIFA), or with Schistosoma mansoni eggs. Fourteen days later, sensitized mice were challenged by tail-vein injection of naked beads, covalently coupled to sodA peptides or to schistosome egg antigens (SEA). Histologic analysis revealed hilar lymphadenopathy and noncaseating granulomas in the lungs of sodA-treated or SEA-treated mice. Flow cytometry of bronchoalveolar lavage (BAL) demonstrated CD4(+) T-cell responses against sodA peptide in the sodA-sensitized mice only. Cytometric bead analysis revealed significant differences in IL-2 and IFN-γ secretion in the BAL fluid of sodA-treated mice, compared with mice that received SEA or naked beads (P = 0.008, Wilcoxon rank sum test). ConNS and ConIFA mice demonstrated no significant formation of granuloma, and no Th1 immunophenotype. The use of microbial peptides distinct for sarcoidosis reveals a histologic and immunologic profile in the murine model that correlates well with those profiles noted in human sarcoidosis, providing the framework to investigate the molecular basis for the progression or resolution of sarcoidosis.

Hypoglycemia due to ectopic secretion of insulin-like growth factor-I in a patient with an isolated sarcoidosis of the spleen

Hypoglycemia is reported to be one of the manifestations of a patient with hypothalamic sarcoid infiltrates due to impaired counter-regulation of glucose. But, without hypothalamic lesion, patients with sarcoidosis would not be expected to have hypoglycemia. We recently identified a patient with an isolated sarcoidosis of the spleen who had experienced frequent fasting hypoglycemia which completely disappeared after splenectomy. During hypoglycemia, serum insulin was undetectable. Endocrinological examination revealed no abnormality. The objective was to investigate whether the patient's hypoglycemia was due to ectopic secretion of an insulin-mimetic factor by the splenic sarcoidosis. Serum insulin-like growth factor-I (IGF-I) and IGF-II were measured by RIA. Serum visfatin and free IGF-I were by ELISA. A high molecular weight form of IGF-II, termed "big" IGF-II, was identified by Western blotting. Tissue IGF-I was quantified by real time RT-PCR after RNA extraction. Before operation, total and free serum IGF-I, serum IGF-II and serum visfatin were within reference range. Big IGF-II was not detected in patient's serum extract. After operation, hypoglycemia did not recur and serum insulin returned to normal, while serum IGF-I decreased by half the preoperative level. RT-PCR revealed that mRNA level of IGF-I in the sarcoidosis tissue was about 1.8-fold greater than that in the normal spleen tissue. These data suggest that ectopic secretion of IGF-I by the splenic sarcoidosis and its direct access to the liver via the portal vein might cause fasting hypoglycemia mainly by suppressing hepatic gluconeogenesis.

The role of inflammatory mediators in the pathogenesis of otitis media and sequelae

This review deals with the characteristics of various inflammatory mediators identified in the middle ear during otitis media and in cholesteatoma. The role of each inflammatory mediator in the pathogenesis of otitis media and cholesteatoma has been discussed. Further, the relation of each inflammatory mediator to the pathophysiology of the middle and inner ear along with its mechanisms of pathological change has been described. The mechanisms of hearing loss including sensorineural hearing loss (SNHL) as a sequela of otitis media are also discussed. The passage of inflammatory mediators through the round window membrane into the scala tympani is indicated. In an experimental animal model, an application of cytokines and lipopolysaccharide (LPS), a bacterial toxin, on the round window membrane induced sensorineural hearing loss as identified through auditory brainstem response threshold shifts. An increase in permeability of the blood-labyrinth barrier (BLB) was observed following application of these inflammatory mediators and LPS. The leakage of the blood components into the lateral wall of the cochlea through an increase in BLB permeability appears to be related to the sensorineural hearing loss by hindering K⁺ recycling through the lateral wall disrupting the ion homeostasis of the endolymph. Further studies on the roles of various inflammatory mediators and bacterial toxins in inducing the sensorineumral hearing loss in otitis media should be pursued.

[Systemic granulomatosis of infectious origin]

PURPOSE

Granulomatous diseases are defined by specific histological features, following the local recruitment of macrophages and lymphocytes. Many infections can lead to the development of granuloma.

CURRENT KNOWLEDGE AND KEY POINTS

Microorganisms responsible for granuloma include mainly mycobacteria, many viral and fungal species, as well as schistosoma in endemic areas. Nevertheless, almost all microorganisms can lead to granuloma, especially if their clearance needs macrophages pathway. New immunosuppressive drugs such as tumor necrosis factor antagonists are associated with a high risk of infectious granulomatous complications. All patients with granuloma must be carefully screened to find a potential underlying infection, since an immunosuppressive therapy could be otherwise considered. We here review the general diagnostic process with a specific glance to the main organs.

FUTURE PROSPECTS AND PROJECTS

Without clinical or epidemiological clue, diagnosis can be very tedious. New molecular tools now assist classical microbiological and histological techniques. Their specificity and sensitivity have recently been better characterized, and their use will probably increase in the near future for the diagnosis of infectious granuloma. They may also lead to discover new infectious aetiologies of granulomatous diseases formerly considered as idiopathic. We describe here the main microorganisms that can be responsible for granuloma, with a specific focus on the use of new diagnostic tools.

Molecular and supra-molecular structure related differences in toxicity and granulomatogenic activity of mycobacterial cord factor in mice

To establish the structure biological activity relationship of cord factor (trehalose 6,6'-dimycolate, TDM), we compared the molecular or supra-molecular structure of TDM micelles with toxicity, thymic atrophy and granulomatogenicity in lungs and spleen of BALB/c mice. According to the difference in the mycolyl subclass composition, TDM was divided into two groups, one possessing alpha-, methoxy- and keto-mycolates in M. tuberculosis H37Rv, M. bovis BCG and M. kansasii (group A) and the other having alpha-, keto- and wax ester-mycolates in M. avium serotype 4, M. phlei and M. flavescens (group B), although mycolic acid molecular species composition differed in each group considerably. Supra-molecular structure of TDM micelle differed species to species substantially and the micelle size of TDM from M. bovis BCG Connaught was the largest. The highest toxicity was shown with TDM from M. tuberculosis H37Rv which possessed the highest amount of alpha- (47.3%) and methoxy-mycolates (40.8%), while TDM from M. phlei having the low amount of alpha-mycolate (11.6%) showed almost no toxicity with the given doses. The thymic atrophy was observed with TDM from group A, but not with TDM from group B. On the other hand, TDM from group B showed massive lung granulomatogenic activity based on the histological observations and organ indices. Taken together, group A TDM showed a wide variety of micelle sizes and specific surface areas, high to low toxicity and marked to moderate granulomatogenicity, while group B TDM showed smaller sizes of micelles and larger specific surface areas, lower toxicity but higher granulomatogenicity in lungs. Existence of higher amount of longer chain alpha-mycolates in TDM appeared to be essential for high toxicity and thymic apoptotic activity, whereas TDM possessing wax ester-mycolate with smaller sized micelles seemed to be less toxic, but more granulomatogenic in lungs in mice. Thus, the mycolic acid subclass and molecular species composition of TDM affect critically the micelle forms, toxicity and granulomatogenicity in mice, while the relative abundances and carbon chain length of alpha-mycolate affected the toxicity in mice.

Mycobacterial sulfolipid shows a virulence by inhibiting cord factor induced granuloma formation and TNF-alpha release

Virulence mechanism of infection with Mycobacterium tuberculosis is currently focused to be clarified in the context of cell surface lipid molecule. Comparing two mycobacterial glycolipids, we observed toxicity and prominent granulomatogenic activity of trehalose 6,6'-dimycolate (TDM) injection in mice, evident by delayed body weight gain and histological observations, whereas 2,3,6,6'-tetraacyl trehalose 2'-sulfate (SL) was non-toxic and non-granulomatogenic. Likewise, TDM but not SL caused temporarily, but marked increase of lung indices, indicative of massive granuloma formation. Interestingly, co-administration of TDM and SL prevented these symptoms distinctively and SL inhibited TDM-induced release of tumor necrosis factor alpha (TNF-alpha) in a dose-dependent manner. Histological findings and organ index changes also showed marked inhibition of TDM induced granuloma formation by co-administration of SL. Simultaneous injection of SL together with TDM was highly effective for this protection, as neither injection 1h before nor after TDM injection showed highly inhibitory. In parallel studies on a cellular level, TDM elicited strong TNF-alpha release from alveolar but not from peritoneal macrophages in vitro. This effect was blocked when alveolar macrophages were incubated in wells simultaneously coated with TDM and SL, indicating that SL suppresses TDM-induced TNF-alpha release from macrophages. Our results suggest a novel mechanism by which SL could contribute to virulence at early stage of mycobacterial infection or stimulation with the glycolipids by counteracting the immunopotentiating effect of TDM.

Expression of chemokines and gelatinase B in sympathetic ophthalmia

PURPOSE

To examine the expression of gelatinase B (matrix metalloproteinase-9) and the chemokines monocyte chemotactic protein-1 (CCL2/MCP-1) and stromal cell-derived factor-1 (CXCL12/SDF-1) in sympathetic ophthalmia (SO).

METHODS

Five enucleated exciting eyes with a clinical diagnosis and typical histopathological findings of SO were studied by immunohistochemical techniques using a panel of monoclonal antibodies directed against gelatinase B, MCP-1, and SDF-1. In addition, a panel of monoclonal and polyclonal antibodies was used to characterize the composition of the inflammatory infiltrate.

RESULTS

In all cases, the extensive uveal inflammatory infiltrate was organized as a diffuse infiltrate and as large granulomas consisting of epithelioid cells and multinucleated giant cells. CD20(+) B lymphocytes predominated in the diffuse infiltrate and CD3(+) T lymphocytes were few. The monocyte/macrophage marker CD68 was expressed in scattered inflammatory mononuclear cells and within granulomas and Dalen-Fuchs nodules. Most of the inflammatory cells were HLA-DR(+). Immunoreactivity for gelatinase B, MCP-1, and SDF-1 was observed in cells within granulomas and in scattered epithelioid cells. Immunoreactivity for MCP-1 was noted in retinal pigment epithelial cells. Endothelial cells of choriocapillaries showed weak immunoreactivity for SDF-1.

CONCLUSIONS

Gelatinase B, MCP-1, and SDF-1 might have a pathogenic role in the recruitment of leucocytes into the eye in SO.

Clinical investigation: increased serum stromal derived factor 1 alpha levels in pulmonary tuberculosis

Pulmonary tuberculosis, a granulomatous disease, has few serological markers for its activity. Recently, an increased plasma level of stromal derived factor 1 alpha (SDF-1alpha), which can induce strong chemotaxis of cells through its receptor CXCR4, was detected in patients with tuberculosis. In this study we investigated serum SDF-1alpha levels and CXCR4 expression on peripheral blood mononuclear cells (PBMCs). Fifty-five active tuberculosis patients, 30 resolved tuberculosis patients, 27 acute bronchitis patients and 8 healthy volunteers were examined. Histological expression of SDF-1alpha in the tuberculosis lesion and CXCR4 expression of PBMCs were also analysed. Serum SDF-1alpha levels in active tuberculosis patients were significantly higher than other groups. The sensitivity and specificity for the diagnosis of active tuberculosis was 88.5% and 85.3% (cutoff value = 650 pg/ml), respectively. CXCR4 expression levels on PBMCs showed a significant negative correlation with serum SDF-1alpha levels. Inflammatory cells including multinuclear giant cells in the lesion expressed SDF-1alpha. Measurement of serum SDF-1alpha could be a useful screening marker for the identification of active pulmonary tuberuculosis. We propose that interaction of SDF-1alpha and CXCR4 might be involved in the pathogenesis of pulmonary tuberculosis.

Production of granulomatous inflammation in lungs of rat pups and adults by Sephadex beads

Granulomatous inflammation is a process that involves mononuclear leukocytes as well as other inflammatory cells. The heterogeneity of its appearance may be due to the variety of cytokines and chemokines that are involved. In this study, we compared granuloma formation and bronchoalveolar leukocyte differential in the lungs of rats (2- and 8-wk-old) that were treated intravenously with Sephadex beads. In addition, the kinetics of cytokine and chemokine production was determined in these groups. In adults, the beads caused lung granulomas associated with infiltration of eosinophils and neutrophils and increased eosinophil and neutrophil counts in the bronchoalveolar lavage fluid within 16 h. In pups, the granulomas were formed slowly and did not reach the size achieved in adults. Eosinophils and neutrophils were sparsely found in the periphery of the granulomas, even at 32 h. Pups were also unable to respond rapidly to Sephadex bead treatment with eosinophil and neutrophil infiltration in the bronchoalveolar lavage fluid. Tumor necrosis factor-alpha was significantly increased in both groups, but the cytokine was lower in pups than in adults. Interferon-gamma and eotaxin were increased only in adults, and IL-4 and regulated on activation, normal T cell expressed, and secreted was increased only in pups. In conclusion, the i.v. administration of Sephadex beads produced granulomatous inflammation in the lungs of adult rats, but pups were unable to respond as rapidly to the treatment. In addition, the difference in response between the two age groups was associated with the kinetics of cytokine and chemokine production.

Vitamin A reduces lung granulomatous inflammation with eosinophilic and neutrophilic infiltration in Sephadex-treated rats

Vitamin A is known to suppress the activity of the transcription factors, nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1), as do glucocorticoids. The possibility that vitamin A exerts various anti-inflammatory effects therefore seems likely. Sephadex beads were administered intravenously to anesthesized rats pretreated with a subcutaneous injection of vitamin A (3000, 10,000, or 30,000 IU/kg) or vehicle once daily for 3 days. After 16 h, the leukocyte differential, tumor necrosis factor (TNF)-alpha and eotaxin, and the DNA-binding activity of NF-kappaB were measured in bronchoalveolar lavage fluid (BALF). Additionally, lung histology was assessed using preparations stained with May-Giemsa stain. Sephadex beads caused histological granulomatous changes and eosinophilic and neutrophilic infiltration into the lung, and markedly increased cell counts of eosinophils and neutrophils, concentrations of TNF-alpha and eotaxin, and NF-kappaB binding to DNA in BALF. Vitamin A significantly inhibited all responses. Vitamin A may inhibit Sephadex-induced lung granulomatous formation, and eosinophilic and neutrophilic infiltration due to its suppression of TNF-alpha and eotaxin production, and NF-kappaB activation.

Differential Stimulation of Microglial Pro-Inflammatory Cytokines by Acanthamoeba culbertsoni versus Acanthamoeba castellanii

Acanthamoeba spp. are opportunistic pathogens that cause granulomatous amebic encephalitis. We compared the highly pathogenic species A. culbertsoni to the relatively less pathogenic species A. castellanii for its capacity to elicit from neonatal rat microglia the gene expression of pro-inflammatory cytokines. Acanthamoeba culbertsoni elicited a robust cytokine gene response by neonatal rat microglia in vitro as compared to A. castellanii. The preponderant cytokine elicited at the mRNA and protein levels was interleukin-1beta. In addition, transmission electron microscopy revealed that microglial cells were capable of phagocytozing A. castellanii. In contrast, A. culbertsoni destroyed microglia. Collectively, these results suggest that a combined action of pro-inflammatory cytokines and destruction of host cells by amebae contribute to the pathology caused by the more pathogenic species.

Etanercept for the treatment of stage II and III progressive pulmonary sarcoidosis

BACKGROUND

Tumor necrosis factor (TNF)-alpha is produced by macrophages and other cells, and is believed to participate in granulomatous inflammation. Targeted antagonism of TNF-alpha has been proposed as a novel treatment strategy for sarcoidosis. Etanercept is a dimeric fusion protein that binds specifically to TNF-alpha, rendering it biologically inactive.

OBJECTIVE

To assess whether etanercept has potential efficacy in the treatment of progressive pulmonary sarcoidosis.

DESIGN

Prospective, open-label, phase-2 treatment trial.

SETTING

Mayo Clinic, Rochester, MN.

PATIENTS

Stage II or III progressive pulmonary sarcoidosis.

INTERVENTION

Etanercept, 25 mg subcutaneously twice weekly.

MEASUREMENTS

Pulmonary function, chest radiographs, dyspnea, and TNF-alpha levels in serum and BAL fluid.

RESULTS

The study was terminated after the enrollment of 17 patients due to an early-stop clause of the pretrial study design related to excessive treatment failures. Neither absolute levels of TNF-alpha nor TNF-alpha activity in the serum, BAL fluid, or alveolar macrophages were able to predict which patients would respond to etanercept.

CONCLUSIONS

In patients with progressive stage II or III pulmonary sarcoidosis, etanercept was frequently associated with early or late treatment failure. These data would not support the design of a large multicenter randomized trial comparing etanercept with conventional corticosteroid therapy.

The role of the host immune response in pathogenesis of Bartonella henselae

Bartonella henselae can infect humans resulting in a wide range of disease syndromes including cat-scratch disease, fever with bacteremia, endocarditis, bacillary angiomatosis, and bacillary peliosis hepatis, among others. The nature and severity of the clinical presentation correlates well with the status of the hosts' immune system. Individuals with impaired immune function, including HIV infection, progress to systemic infections more often. Patients with intact immune function who become infected with B. henselae usually get cat-scratch disease, a disease that usually involves lymphadenopathy resulting from a strong cellular immune response to the bacterium. However, immunocompromised patients often progress to bacillary angiomatosis or bacillary peliosis hepatis. The reduced ability of the hosts immune response to control bacterial infection apparently results in a bacteremia of longer duration, and in some patients the presence of angiogenic lesions that are unique among bacterial infections to Bartonella. Recently, the role of immune effector cells that produce angiogenic cytokines upon stimulation with B. henselae has been proposed. Here, the current status of the role of the immune response in both controlling infection and in B. henselae-triggered immunopathogenesis is presented.

Expression of monocyte chemoattractant protein-1 but not interleukin-8 in granulomatous lesions in lymph nodes from pigs with naturally occurring postweaning multisystemic wasting syndrome

Monocyte chemoattractant protein-1 (MCP-1) but not interleukin-8 (IL-8) was detected by in situ hybridization using a nonradioactive digoxigenin-labeled complementary DNA probe in granulomatous lesions of lymph nodes from 20 pigs with naturally occurring postweaning multisystemic wasting syndrome (PMWS). Complementary DNA probes of 375 and 266 base pairs for MCP-1 and IL-8, respectively, were generated by reverse transcription-polymerase chain reaction. The 20 pigs with PMWS had distinct positive hybridization signals for MCP-1 but not for IL-8. The hybridization signals for MCP-1 were strictly confined to the cells with granulomatous lesions, including macrophages and multinucleated giant cells. A very close cell-to-cell correlation between MCP-1 and porcine circovirus 2 was seen in serial sections of lymph nodes. Results of this study indicate that MCP-1 expression may play a role in the pathogenesis of granulomatous inflammation in pigs with PMWS.

The cytokine network in sarcoidosis and its clinical relevance

In recent years, analysis of the cytokine network has substantially improved our knowledge of the immunopathogenesis of sarcoidosis. There is increasing evidence from clinical immunology that analysis of the cytokine network may be helpful for clinicians to assess the extent and activity of sarcoid inflammation. Genetic polymorphisms may contribute to interindividual differences in the regulation of cytokine release. Thus, disease phenotype-associated haplotypes should exist and their analysis might disclose risk profiles of individual patients. Furthermore, serological assessment of cytokines or soluble cytokine receptors may become suitable parameters in clinical practice to detect an ongoing inflammation in chronic sarcoidosis.

Immunological properties of trehalose dimycolate (cord factor) and other mycolic acid-containing glycolipids--a review

Mycolic acids are characteristic fatty acids of Mycobacteria and are responsible for the wax-like consistence of these microorganisms. Decades of research revealed that mycolic acid-containing glycolipids, in particular trehalose-6,6'-dimycolate (TDM, cord factor) as their best-studied representative, exert a number of immunomodifying effects. They are able to stimulate innate, early adaptive and both humoral and cellular adaptive immunity. Most functions can be associated with their ability to induce a wide range of chemokines (MCP-1, MIP-1alpha, IL-8) and cytokines (e.g., IL-12, IFN-gamma, TNF-alpha, IL-4, IL-6, IL-10). This review tries to link well-known properties of mycolic acid-containing glycolipids, e.g., stimulation of cellular and humoral immunity, granuloma formation and anti-tumor activity, with recent findings in molecular immunology and to give an outlook on potential practical applications.

Dendritic cell involvement in pulmonary granuloma formation elicited by bacillus calmette-guérin in rats

Dendritic cells (DCs) are the most potent antigen-presenting cells that play a central role in initiating the primary immune response. However, their role in granulomatous inflammation has not been well studied. The aim of the present study was to elucidate the role of DCs in granuloma formation. Using a rat model of bacillus Calmette-Guérin (BCG)-elicited pulmonary granulomas, we investigated the distribution of DCs in the granulomas by immunohistochemistry with a rat-DC-specific monoclonal antibody, OX62. We found numerous large, pleiomorphic OX62(+) cells accumulating at the borders of the pulmonary granulomas. The OX62(+) cells isolated from the granulomatous lung showed intense surface expression of major histocompatibility complex class II, B7-1, and B7-2, and a lack of T cell- and monocyte/macrophage-specific markers. Their ultrastructural morphology was characteristic of DCs. Functionally, they had potent capacity to stimulate allogeneic T cells as well as purified protein derivative-specific syngeneic T cells in the absence of exogenous peptides. Based on these findings, the OX62(+) cells infiltrating the granulomas were considered to be DCs expressing BCG-derived peptides. These results indicate that DCs contribute to pulmonary granuloma formation elicited by BCG by means of their potent antigen-presenting function, providing a novel insight into DC function in T cell-mediated granulomatous immune responses.

Dual role for nitric oxide in paracoccidioidomycosis: essential for resistance, but overproduction associated with susceptibility

Using a murine model of susceptibility and resistance to paracoccidioidomycosis, we have previously demonstrated that immunosuppression occurs in susceptible (B10.A), but not in resistant (A/Sn), mouse strains. Accumulating evidence shows that NO is involved in the induction of T cell immunosuppression during infection as well as in the killing of Paracoccidioides brasiliensis. In the present work, we focused on NO and other macrophage products that could be associated with resistance or susceptibility to paracoccidioidomycosis. A striking difference was related to NO and TNF production. Macrophages from B10.A mice produced high and persistent NO levels, while in A/Sn animals, TNF production predominated. In in vitro cultures, P. brasiliensis-infected macrophages from A/Sn mice also produced large amounts of TNF, while B10.A macrophages only produced NO. TNF production by B10.A macrophages appeared to be suppressed by NO, because the addition of aminoguanidine sulfate, an inducible NO synthase (NOS2) inhibitor, resulted in TNF production. These results suggested that enhanced TNF or NO production is associated with resistance and susceptibility, respectively. However, regardless of the mouse strain, NOS2-deficient or aminoguanidine sulfate-treated mice presented extensive tissue lesions with increased fungal load in lungs and liver compared with their controls. We conclude that NOS2-derived NO is essential for resistance to paracoccidioidomycosis, but overproduction is associated with susceptibility.

Analysis of the temporal expression of chemokines and chemokine receptors during experimental granulomatous inflammation: role and expression of MIP-1alpha and MCP-1

1. Chemokine expression and function was monitored in an experimental model of granulomatous tissue formation after injection of croton oil in complete Freund's adjuvant (CO/CFA) into mouse dorsal air-pouches up to 28 days. 2. In the first week, mast cell degranulation and leukocyte influx (mononuclear cell, MNC, and polymorphonuclear cell, PMN) were associated with CXCR2, KC and macrophage inflammatory protein (MIP)-2 mRNA expression, as determined by TaqMan reverse transcriptase-polymerase chain reaction. KC ( approximately 400 pg x mg protein(-1), n=12) and MIP-2 (approximately 800 pg x mg protein(-1), n=12) proteins peaked at day 7, together with myeloperoxidase (MPO) activity. Highest MIP-1alpha (>1 ng x mg protein(-1), n=12) levels were measured at day 3. 3. After day 7, a gradual increase in CCR2 and CCR5 mRNA, monocyte chemoattractant protein (MCP)-1 mRNA and protein expression was measured. MCP-1 protein peaked at day 21 (approximately 150 pg x mg protein(-1), n=12) and was predominantly expressed by mast cells. A gradual increase in N-acetyl-beta-D-glucosaminidase (NAG) activity (maximal at 28 days) was also measured. 4. An antiserum against MIP-1alpha did not modify the inflammatory response measured at day 7 (except for a 50% reduction in MIP-1alpha levels), but provoked a significant increase in MPO, NAG and MCP-1 levels as measured at day 21 (n=6, P<0.05). An antiserum to MCP-1 reduced NAG activity at day 21 but increased MPO activity values (n=8, P<0.05). 5. In conclusion, we have shown that CO/CFA initiates a complex inflammatory reaction in which initial expression of MIP-1alpha serves a protective role whereas delayed expression of MCP-1 seems to have a genuine pro-inflammatory role.

Inhibition of monocyte chemoattractant protein-1 expression in cytokine-treated human lung epithelial cells by thiazolidinedione

STUDY OBJECTIVE

Several lung diseases are characterized by the presence of increased numbers of activated macrophages. The recruitment and activation of peripheral blood monocytes are potentially critical regulatory events for the control of pulmonary inflammation. The chemokine monocyte chemoattractant protein (MCP)-1 is a potent chemoattractant for monocytes. MCP-1 is produced by lung epithelial cells during the course of inflammatory lung diseases. In the present study, we examined the effects of a thiazolidinedione (TZD), which is used to improve the insulin resistance of individuals with diabetes mellitus, on MCP-1 expression in a human lung epithelial cell line, A549.

MEASUREMENTS AND RESULTS

In A549 cells, interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha induced endogenous MCP-1 protein secretion and messenger RNA expression. The TZD inhibited the increase of MCP-1 secretion by IL-1beta and TNF-alpha treatment. The TZD inhibited the expression of MCP-1 messenger RNA with IL-1beta treatment, but not with TNF-alpha treatment. This observation was confirmed by the results of a monocyte chemotactic assay. The transcriptional activity of human MCP-1 promoter in A549 cells paralleled the endogenous messenger RNA expression by cytokines and TZD treatment.

CONCLUSIONS

Our findings indicated that the suppression of the expression of MCP-1 could be accomplished by TZD treatment, raising the possibility that TZD may be of therapeutic value in several lung diseases in which MCP-1 plays an important role.

Immunopathogenesis of delayed-type hypersensitivity

Cell-mediated immunity is defined as a beneficial host response characterized by an expanded population of specific T cells, which, in the presence of antigens, produce cytokines locally. The activation and recruitment of cells into an area of inflammation is a crucial step in the development of DTH responses. DTH is immunologically a process similar to cell-mediated immunity, involving T cells and cytokines. CD4 T helper (Th) 1 cells, differentiated from naive Th cells by IL-12 and IL-18 produced from macrophages, play a regulatory role in the expression of DTH and activation of macrophages via interferon gamma generated by Th1 and natural killer cells. Macrophages accumulate at the site of DTH and become activated through the CD4 Th1 cell-cytokine-macrophage axis. However, DTH leads to pathologic responses, such as granulomatous inflammation, calcification, caseation necrosis, and cavity formation. Granulomas usually form as a result of the persistence of a nondegradable product or as the result of DTH responses. DTH is also required for host defense against etiologic agents, such as Mycobacterium tuberculosis. The expression of cell-mediated immunity/DTH is a double-edged sword that may contribute to both clearance of the etiologic agent and tissue damage.

Type 2-biased expression of cytokine genes in lung granulomatous lesions induced by Nippostrongylus brasiliensis infection

Infections with helminthic parasites occasionally induce pulmonary diseases with possible involvement of immunological mechanisms. In rats infected with the nematode Nippostrongylus brasiliensis, pulmonary granulomatous lesions develop and persist after the larvae have migrated through the lungs. To determine the pathogenesis of this lesion, we examined cytokine gene expression in the lungs using RT-PCR and in situ hybridization. Two weeks after infection, when fully developed lesions appeared, levels of IL-3 and of type2 cytokines IL-4, IL-5, IL-6 and IL-13 gene expression were markedly enhanced in whole lung homogenates. Those of IL-2 and IFN-gamma were also slightly increased 2 weeks postinfection. IL-12 mRNA level did not change after 2 weeks but was slightly increased after 4 weeks. Levels of IL-10 and proinflammatory cytokine TNF gene expression did not show significant changes, although a slight increase was observed in IL-1beta message after 2 weeks. In situ hybridization studies showed that lung granulomatous lesions were composed mainly of lymphoid cells expressing IL-3, IL-4 and IL-13 mRNA, but not IFN-gamma mRNA. IL-5 mRNA-expressing cells were fewer in number than these cells. RMCP II immunohistochemistry revealed that mast cells increased in number in the lung granulomas. From these results, it was concluded that the nematode infection-associated lung granuloma was a type 2 lesion.

Pneumocystis carinii pneumonia with an atypical granulomatous response in a patient with chronic lymphocytic leukemia

We have recently seen a patient who developed Pneumocystis carinii pneumonia (PCP) in the course of treatment for chronic lymphocytic leukemia (CLL). This case showed uncommon pathological findings with extensive formation of granulomatous lesions. Despite advanced CLL associated with poor B-cell function, she responded well to anti-PCP treatment. In contrast to B-cell function, the T-cell functions were well preserved in vitro, and the numbers of peripheral CD4- and CD8-positive cells were normal, and T-cell functions were normal. These findings suggest that the production of granulomatous lesions to PCP may have been associated with the patients' immune status, and that it may constitute a good indicator in PCP infection in patients with underlying hematological malignancy.

Trehalose 6,6'-dimycolate (cord factor) of Mycobacterium tuberculosis induces foreign-body- and hypersensitivity-type granulomas in mice

Granulomatous inflammation is characterized morphologically by a compact organized collection of macrophages and their derivatives. It is classified as either a hypersensitivity type or a foreign-body type. Lipid components of the Mycobacterium tuberculosis cell wall participate in the pathogenesis of infection. Strains of M. tuberculosis have cord factor (trehalose 6,6'-dimycolate [TDM]) on their surface. To clarify host responses to TDM, including immunogenicity and pathogenicity, we have analyzed the footpad reaction, histopathology, and cytokine profiles of experimental granulomatous lesions in immunized and unimmunized mice challenged with TDM. In the present study, we have demonstrated for the first time that TDM can induce both foreign-body-type (nonimmune) and hypersensitivity-type (immune) granulomas by acting as a nonspecific irritant and T-cell-dependent antigen. Immunized mice challenged with TDM developed more severe lesions than unimmunized mice. At the active lesion, we found monocyte chemotactic, proinflammatory, and immunoregulatory cytokines. The level was enhanced in immunized mice challenged with TDM. This result implies that both nonimmune and immune mechanisms participate in granulomatous inflammation induced by mycobacterial infection. Taken together with a previous report, this study shows that TDM is a pleiotropic molecule against the host and plays an important role in the pathogenesis of tuberculosis.

Environmental immunogens and T-cell-mediated responses in fibromyalgia: evidence for immune dysregulation and determinants of granuloma formation

Thirty-nine patients with fibromyalgia syndrome (FMS) according to American College of Rheumatology criteria were studied for cell-mediated sensitivity to environmental chemicals. Lymphocytes were tested by standard [(3)H]thymidine incorporation in vitro for T cell memory to 11 chemical substances. Concanavalin A (Con A) was used to demonstrate T cell proliferation. Controls were 25 contemporaneous healthy adults and 252 other concurrent standard controls without any aspect of FMS. Significantly higher (P < 0.01) stimulation indexes (SI) were found in FMS for aluminum, lead, and platinum; borderline higher (0.05 > P > 0.02) SI were found for cadmium and silicon. FMS patients showed sporadic responses to the specific substances tested, with no high-frequency result (>50%) and no obvious pattern. Mitogenic responses to Con A indicated some suppression of T cell functionality in FMS. Possible links between mitogenicity and immunogenic T cell proliferation, certain electrochemical specifics of granuloma formation, maintenance of connective tissue, and the fundamental nature of FMS are considered.

Trehalose 6,6'-dimycolate (cord factor) of Mycobacterium tuberculosis induces corneal angiogenesis in rats

Neovascularization or angiogenesis is required for the progression of chronic inflammation. The mechanism of inflammatory neovascularization in tuberculosis remains unknown. Trehalose 6, 6'-dimycolate (TDM) purified from Mycobacterium tuberculosis was injected into rat corneas. TDM challenge provoked a local granulomatous response in association with neovascularization. Neovascularization was seen within a few days after the challenge, with the extent of neovascularization being dose dependent, although granulomatous lesions developed 14 days after the challenge. Cytokines, including tumor necrosis factor alpha (TNF-alpha), interleukin-8 (IL-8), IL-1beta, and vascular endothelial growth factor (VEGF), were found in lesions at the early stage (within a few days after the challenge) and were detectable until day 21. Neovascularization was inhibited substantially by neutralizing antibodies to VEGF and IL-8 but not IL-1beta. Treatment with anti-TNF-alpha antibodies resulted in partial inhibition. TDM possesses pleiotropic activities, and the cytokine network plays an important role in the process of neovascularization.

The role of osteopontin in the development of granulomatous lesions in lung

Osteopontin (OPN) has been shown to be expressed by cells in granulomas of various origins, but whether it plays a functional role in granuloma formation is not known. Here we used a cardiomyopathic hamster (TO2) model, to test the hypothesis that OPN contributes functionally to granuloma development. We immunized cardiomyopathic and normal hamsters by subcutaneous injection of bovine serum albumin in complete Freund's adjuvant, and assessed various tissues for both OPN RNA expression and granuloma formation. Cardiomyopathic hamsters expressed OPN, and formed granulomatous lesions, in heart tissue in both immunized and untreated animals. In addition, immunization induced expression of OPN in lung and lymph nodes of cardiomyopathic (but not normal) hamsters, and also induced granuloma formation in these organs. To test whether OPN expression could play a functional role in inducing granulomas, we produced an adenoviral vector containing the murine OPN gene, and introduced this vector intratracheally into the lungs of normal hamsters. The OPN-containing vector, but not the control vector, induced pulmonary granuloma formation. These studies provided direct in vivo evidence that OPN can contribute functionally to the formation of granulomatous lesions, and suggest that OPN expression may be a common factor involved in formation of granulomas of various origin.