New Findings of Immunodysregulation, Polyendocrinopathy, and Enteropathy X-linked Syndrome (IPEX); Granulomas in Lung and Duodenum.

Immune dysregulation, polyendocrinopathy and enteropathy, X-linked (IPEX) syndrome is a rare disorder caused by loss-of-function mutations in the gene forkhead box protein 3 (FOXP3). IPEX patients frequently show chronic diarrhea (enteropathy) associated with villous atrophies in the small intestine. Our case is different from this classical information in the literature, since he presented with neonatal onset inflammatory bowel disease within the first months of life accompanied by deep ulcers throughout colonic mucosa. Moreover, he developed chronic lung disease during follow-up and histopathological examinations showed granulomas in both gastrointestinal tract and lung parenchyma. Genetic analysis revealed the diagnosis of IPEX syndrome with a germline mutation in FOXP3. Thus, our study provides an unusual presentation of IPEX syndrome with colitis and granulomas presence in histopathological examinations.

Microparticles in the pathogenesis of TB: Novel perspectives for diagnostic and therapy management of Mycobacterium tuberculosis infection.

Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis, usually chronic and has a progressive clinical course. Despite the availability of effective chemotherapy, TB is a leading killer of young adults worldwide and the global multi-drug resistant TB is reaching epidemic proportions. Interrupt transmission through early detection and treatment of the patients is a main element of the drug-resistant TB control strategy. However, many drugable targets in pathogens are already inhibited by current antibiotics and there is not a biomarker that indicate normal or pathogenic biological processes, or pharmacological responses to therapeutic intervention. Studies directed at evaluate key elements of host response to infection may identify biomarkers with measurable characteristics that indicate pathogenic biological processes. Cell-derived microparticles (MPs) are membrane-coated vesicles that represent subcellular elements and have been identified increasingly in a broad range of diseases and emerging as potential novel biomarker to pathological processes. In addition, MPs carry contents from their cells of origin as bioactive molecules as cytokines, enzymes, surface receptors, antigens and genetic information and may provide a means of communication between cells. Molecules-loaded MPs may interplay with the immune system and therefore can acts on inflammation, cell activation and migration. Therefore, MPs may be an important factor to immune process during Mtb infection, especially in pulmonary granulomas and influence the outcome of infection. Their characterization may facilitate an appropriate diagnosis, optimize pharmacological strategies and might be further explored as potential targets for future clinical interventions.

The End of the Binary Era: Revisiting the Spectrum of Tuberculosis.

Human Mycobacterium tuberculosis infection was thought to result in either active symptomatic tuberculosis (TB) or latent asymptomatic infection. It is now clear that this binary classification is insufficient to describe the myriad of infection outcomes. In active TB, symptomatic disease can be mild to severe, with a range of lung and thoracic lymph node involvement or extrapulmonary manifestations. Most humans control the infection and develop latent TB infection, with differential risks of reactivation to active TB. However, some frequently exposed persons appear to be resistant to infection, whereas others may initially become infected yet subsequently eliminate all bacilli. The immunologic factors influencing these varied outcomes are still not clear, but likely involve a range of different responses. In this article, we review the data supporting the spectrum of M. tuberculosis infection in humans as well as data in nonhuman primates that allow dissection of the immune responses leading to the varied outcomes of infection.

The transpeptidase PbpA and noncanonical transglycosylase RodA of Mycobacterium tuberculosis play important roles in regulating bacterial cell lengths.

The cell wall of Mycobacterium tuberculosis (Mtb) is a complex structure that protects the pathogen in hostile environments. Peptidoglycan (PG), which helps determine the morphology of the cell envelope, undergoes substantial remodeling under stress. This meshwork of linear chains of sugars, cross-linked through attached peptides, is generated through the sequential action of enzymes termed transglycosylases and transpeptidases. The Mtb genome encodes two classical transglycosylases and four transpeptidases, the functions of which are not fully elucidated. Here, we present work on the yet uncharacterized transpeptidase PbpA and a nonclassical transglycosylase RodA. We elucidate their roles in regulating in vitro growth and in vivo survival of pathogenic mycobacteria. We find that RodA and PbpA are required for regulating cell length, but do not affect mycobacterial growth. Biochemical analyses show PbpA to be a classical transpeptidase, whereas RodA is identified to be a member of an emerging class of noncanonical transglycosylases. Phosphorylation of RodA at Thr-463 modulates its biological function. In a guinea pig infection model, RodA and PbpA are found to be required for both bacterial survival and formation of granuloma structures, thus underscoring the importance of these proteins in mediating mycobacterial virulence in the host. Our results emphasize the fact that whereas redundant enzymes probably compensate for the absence of RodA or PbpA during in vitro growth, the two proteins play critical roles for the survival of the pathogen inside its host.

Interstitial lung disease in patients with common variable immunodeficiency disorders: several different pathologies?

Various reports of disease-related lung pathologies in common variable immunodeficiency disorder (CVID) patients have been published, with differing histological and high-resolution computed tomography (HRCT) findings. Data were extracted from the validated Oxford Primary Immune Deficiencies  Database (PID) database (1986-2016) on adult, sporadic CVID patients with suspected interstitial lung disease (ILD). Histology of lung biopsies was studied in relation to length of follow-up, clinical outcomes, HRCT findings and chest symptoms, to look for evidence for different pathological processes. Twenty-nine CVID patients with lung histology and/or radiological evidence of ILD were followed. After exclusions, lung biopsies from 16 patients were reanalysed for ILD. There were no well-formed granulomata, even though 10 patients had systemic, biopsy-proven granulomata in other organs. Lymphocytic infiltration without recognizable histological pattern was the most common finding, usually with another feature. On immunochemistry (n = 5), lymphocytic infiltration was due to T cells (CD4 or CD8). Only one patient showed B cell follicles with germinal centres. Interstitial inflammation was common; only four of 11 such biopsies also showed interstitial fibrosis. Outcomes were variable and not related to histology, suggesting possible different pathologies. The frequent nodules on HRCT were not correlated with histology, as there were no well-formed granulomata. Five patients were asymptomatic, so it is essential for all patients to undergo HRCT, and to biopsy if abnormal HRCT findings are seen. Internationally standardized pathology and immunochemical data are needed for longitudinal studies to determine the precise pathologies and prognoses in this severe complication of CVIDs, so that appropriate therapies may be found.

A Novel In Vitro Human Granuloma Model of Sarcoidosis and Latent Tuberculosis Infection.

Many aspects of pathogenic granuloma formation are poorly understood, requiring new relevant laboratory models that represent the complexity (genetics and diversity) of human disease. To address this need, we developed an in vitro model of granuloma formation using human peripheral blood mononuclear cells (PBMCs) derived from patients with active sarcoidosis, latent tuberculosis (TB) infection (LTBI), or normal healthy control subjects. PBMCs were incubated for 7 days with uncoated polystyrene beads or beads coated with purified protein derivative (PPD) or human serum albumin. In response to PPD-coated beads, PBMCs from donors with sarcoidosis and LTBI formed robust multicellular aggregates resembling granulomas, displaying a typical T-helper cell type 1 immune response, as assessed by cytokine analyses. In contrast, minimal PBMC aggregation occurred when control PBMCs were incubated with PPD-coated beads, whereas the response to uncoated beads was negligible in all groups. Sarcoidosis PBMCs responded to human serum albumin-coated beads with modest cellular aggregation and inflammatory cytokine release. Whereas the granuloma-like aggregates formed in response to PPD-coated beads were similar for sarcoidosis and LTBI, molecular profiles differed significantly. mRNA expression patterns revealed distinct pathways engaged in early granuloma formation in sarcoidosis and LTBI, and they resemble molecular patterns reported in diseased human tissues. This novel in vitro human granuloma model is proposed as a tool to investigate mechanisms of early granuloma formation and for preclinical drug discovery research of human granulomatous disorders. Clinical trial registered with www.clinicaltrials.gov (NCT01857401).

STAT1-dependent and -independent pulmonary allergic and fibrogenic responses in mice after exposure to tangled versus rod-like multi-walled carbon nanotubes.

BACKGROUND: Pulmonary toxicity of multi-walled carbon nanotubes (MWCNTs) is influenced by physicochemical characteristics and genetic susceptibility. We hypothesized that contrasting rigidities of tangled (t) versus rod-like (r) MWCNTs would result in differing immunologic or fibrogenic responses in mice and that these responses would be exaggerated in transgenic mice lacking the signal transducer and activator of transcription-1 (STAT1), a susceptible mouse model of pulmonary fibrosis. METHODS: Male wild type (Stat1 +/+ ) and STAT1-deficient (Stat1 -/- ) mice were exposed to 4 mg/kg tMWCNTs, rMWCNTs, or vehicle alone via oropharyngeal aspiration and evaluated for inflammation at one and 21 days post-exposure via histopathology, differential cell counts, and cytokine levels in bronchoalveolar lavage fluid (BALF). Granuloma formation, mucous cell metaplasia, and airway fibrosis were evaluated by quantitative morphometry. Airway epithelial cell proliferation was assessed by bromodeoxyuridine (BrdU) incorporation. Cytokine protein levels in BALF and serum IgE levels were measured by ELISA. Lung protein Smad2/3 levels and activation were measured by Western blot. Lung mRNAs were measured by PCR. RESULTS: There was a 7-fold difference in rigidity between tMWCNTs and rMWCNTs as determined by static bending ratio. Both MWCNT types resulted in acute inflammation (neutrophils in BALF) after one-day post-exposure, yet only rMWCNTs resulted in chronic inflammation at 21 days as indicated by neutrophil influx and larger granulomas. Both MWCNTs induced BrdU uptake in airway epithelial cells, with the greatest proliferative response observed in rMWCNT-exposed mice after one-day. Only rMWCNTs induced mucous cell metaplasia, but this index was not different between genotypes. Stat1 -/- mice had higher levels of baseline serum IgE than Stat1 +/+ mice. Greater airway fibrosis was observed with rMWCNTs compared to tMWCNTs, and exaggerated airway fibrosis was seen in the Stat1 -/- mouse lungs with rMWCNTs but not tMWCNTs. Increased fibrosis correlated with elevated levels of TGF-ß1 protein levels in the BALF of Stat1 -/- mice exposed to rMWCNTs and increased lung Smad2/3 phosphorylation. CONCLUSIONS: Rigidity plays a key role in the toxicity of MWCNTs and results in increased inflammatory, immunologic, and fibrogenic effects in the lung. STAT1 is an important protective factor in the fibroproliferative response to rMWCNTs, regulating both induced TGF-ß1 production and Smad2/3 phosphorylation status. Therefore, both rigidity and genetic susceptibility should be major considerations for risk assessment of MWCNTs.

Histological Diagnoses of Military Personnel Undergoing Lung Biopsy After Deployment to Southwest Asia.

INTRODUCTION: The current understanding of associations between lung disease and military deployment to Southwest Asia, including Iraq and Afghanistan, is both controversial and limited. We sought to clarify the relation between military deployment and biopsy-proven lung disease. METHODS: Retrospective data were analyzed for military personnel with non-neoplastic lung biopsies evaluated at the Armed Forces Institute of Pathology or Joint Pathology Center (January 2005 to December 2012). RESULTS: Of 391 subjects, 137 (35.0%) had deployed to Southwest Asia prior to biopsy. Compared to non-deployed subjects, those deployed were younger (median age 37 vs. 51 years) with higher representation of African Americans (30.0 vs. 16.9%). Deployed patients were more likely diagnosed with non-necrotizing granulomas (OR 2.4). Non-deployed subjects had higher frequency of idiopathic interstitial pneumonias, particularly organizing pneumonia. Prevalence of small airways diseases including constrictive bronchiolitis was low. CONCLUSIONS: This study provides a broader understanding of diversity of biopsy-proven non-neoplastic lung disease as it relates to military deployment to Southwest Asia and importantly did not show an increased prevalence of small airway disease to include constrictive bronchiolitis.

LIM-only protein FHL2 regulates experimental pulmonary Schistosoma mansoni egg granuloma formation.

LIM-only protein FHL2 is associated with several immune and inflammatory diseases such as arthritis, influenza A virus infection, and lung inflammation. However, the role of FHL2 in macrophage differentiation and in the development of granuloma formation is unknown. Here, we show that expression of FHL2 is induced in mouse bone marrow derived macrophages (BMMs) following stimulation with M2 cytokines such as IL-4 and IL-10. FHL2-knockout (FHL2-KO) BMMs exhibit a proinflammatory M1 phenotype after LPS treatment and display a reduced anti-inflammatory M2 phenotype following IL-4 treatment. Furthermore, thioglycollate-induced migration of macrophages and B cells is enhanced in FHL2-KO mice. To evaluate the importance of FHL2 in the development of pulmonary granuloma formation, FHL2-KO mice were challenged with Schistosoma mansoni eggs. FHL2-KO mice show an enhanced number of granulomas and display decreased expression of Th2 markers and an exacerbated Th1 type of inflammation, characterized by enhanced expression of neutrophil markers and Th1 cytokines. Furthermore, the expression of barrier proteins is reduced in FHL2-KO lung compared to WT. Collectively, these data identify a previously unrecognized role for FHL2 in the pathogenesis of pulmonary granulomatous inflammation, partly through its effect on macrophage polarization, modulation of the Th1/Th2 balance and regulation of permeability in lung.

Versatile myeloid cell subsets contribute to tuberculosis-associated inflammation.

Tuberculosis (TB), a chronic bacterial infectious disease caused by Mycobacterium tuberculosis (Mtb), typically affects the lung and causes profound morbidity and mortality rates worldwide. Recent advances in cellular immunology emphasize the complexity of myeloid cell subsets controlling TB inflammation. The specialization of myeloid cell subsets for particular immune processes has tailored their roles in protection and pathology. Among myeloid cells, dendritic cells (DCs) are essential for the induction of adaptive immunity, macrophages predominantly harbor Mtb within TB granulomas and polymorphonuclear neutrophils (PMNs) orchestrate lung damage. However, within each myeloid cell population, diverse phenotypes with unique functions are currently recognized, differentially influencing TB pneumonia and granuloma functionality. More recently, myeloid-derived suppressor cells (MDSCs) have been identified at the site of Mtb infection. Along with PMNs, MDSCs accumulate within the inflamed lung, interact with granuloma-residing cells and contribute to exuberant inflammation. In this review, we discuss the contribution of different myeloid cell subsets to inflammation in TB by highlighting their interactions with Mtb and their role in lung pathology. Uncovering the manifold nature of myeloid cells in TB pathogenesis will inform the development of future immune therapies aimed at tipping the inflammation balance to the benefit of the host.

[Non-infectious granulomatous inflammation: Focus on the lungs and skin]. / Nichtinfektiöse granulomatöse Entzündungen: Schwerpunkt Lunge und Haut.

Whereas a granulomatous reaction represents a physiologically useful immune defense mechanism against many infections, in autoimmune diseases granuloma formation and the concomitant inflammatory mechanisms may provoke a potentially organ-threatening reaction. Morphologically, several defined sub-types of granuloma have long been known, e.g. foreign body granuloma, tuberculous granuloma,sarcoid, pseudosarcoid, rheumatoid and rheumatic fever granulomas. However, in practice, assigning granulomas to a certain etiology from a biopsy or resection specimen can be a challenging diagnostic process. This article gives a practically oriented overview of the clinically most relevant non-infectious granulomatous diseases. The etiology, epidemiology, clinical correlation and morphology of granulomatous diseases are discussed, focussing on the lungs and skin.

The beryllium bronchoalveolar lavage lymphocyte proliferation test: indicator of beryllium sensitization, inflammation or both?

CONTEXT: We had available records on over 300 workers evaluated with the beryllium bronchoalveolar lavage lymphocyte proliferation test (BeBALLPT) at three expert chronic beryllium disease (CBD) diagnostic centers. OBJECTIVE: The objective was to describe the contribution of the BeBALLPT to classification of workers with respect to beryllium sensitization (BeS) and beryllium-induced lung inflammation. METHODS: Company records were used to identify beryllium workers who had undergone diagnostic bronchoscopy with BeBALLPT. Clinical, work and smoking information was abstracted from electronic and paper databases. We analyzed factors influencing BeBALLPT outcome, and its relation to blood-determined BeS and granulomatous inflammation. RESULTS: Positive BeBALLPTs contributed evidence of BeS in subjects without prior positive beryllium blood lymphocyte proliferation tests (BeBLPTs) and of pulmonary inflammation in persons without granulomata evident on lung biopsy. Positive BeBALLPTs were associated with positive BeBLPTs and more strongly with granulomata. The rate of both positive BeBALLPT and granulomata increased with time worked through 4 years and were lower in smoking subjects. The false negative rate of the BeBALLPT was 20%. CONCLUSION: A positive BeBALLPT is closely linked to the presence of granulomata on lung biopsy and can be considered as an indicator of lung inflammation in addition to BeS. The ability to use BeBALLPT as a substitute for the more risky lung biopsy is limited by the BeBALLPT false negative rate and lack of information on the false positive rate. It is not recommended that a positive BeBALLPT be considered sufficient evidence for both lung inflammation and BeS.

Neutrophils Promote Mycobacterial Trehalose Dimycolate-Induced Lung Inflammation via the Mincle Pathway.

Trehalose 6,6'-dimycolate (TDM), a cord factor of Mycobacterium tuberculosis (Mtb), is an important regulator of immune responses during Mtb infections. Macrophages recognize TDM through the Mincle receptor and initiate TDM-induced inflammatory responses, leading to lung granuloma formation. Although various immune cells are recruited to lung granulomas, the roles of other immune cells, especially during the initial process of TDM-induced inflammation, are not clear. In this study, Mincle signaling on neutrophils played an important role in TDM-induced lung inflammation by promoting adhesion and innate immune responses. Neutrophils were recruited during the early stage of lung inflammation following TDM-induced granuloma formation. Mincle expression on neutrophils was required for infiltration of TDM-challenged sites in a granuloma model induced by TDM-coated-beads. TDM-induced Mincle signaling on neutrophils increased cell adherence by enhancing F-actin polymerization and CD11b/CD18 surface expression. The TDM-induced effects were dependent on Src, Syk, and MAPK/ERK kinases (MEK). Moreover, coactivation of the Mincle and TLR2 pathways by TDM and Pam3CSK4 treatment synergistically induced CD11b/CD18 surface expression, reactive oxygen species, and TNFα production by neutrophils. These synergistically-enhanced immune responses correlated with the degree of Mincle expression on neutrophil surfaces. The physiological relevance of the Mincle-mediated anti-TDM immune response was confirmed by defective immune responses in Mincle⁻/⁻ mice upon aerosol infections with Mtb. Mincle-mutant mice had higher inflammation levels and mycobacterial loads than WT mice. Neutrophil depletion with anti-Ly6G antibody caused a reduction in IL-6 and monocyte chemotactic protein-1 expression upon TDM treatment, and reduced levels of immune cell recruitment during the initial stage of infection. These findings suggest a new role of Mincle signaling on neutrophils during anti-mycobacterial responses.

ICAM-1 deficiency exacerbates sarcoid-like granulomatosis induced by Propionibacterium acnes through impaired IL-10 production by regulatory T cells.

Propionibacterium acnes has been implicated as one of the suggested causative antigens for sarcoidosis, a systemic granulomatous disease. By injecting heat-killed P. acnes into the dorsal skin of C57BL/6J mice on days 1, 3, 5, and 14, sarcoid-like granulomatosis was induced in skin and lungs of these mice on day 28. To clarify the role of cell adhesion molecules in cutaneous sarcoidosis, we induced sarcoid-like granulomatosis in mice deficient of intercellular adhesion molecule (ICAM)-1, L-selectin, P-selectin, or E-selectin via repeated P. acnes injection. Histopathologic analysis revealed that granuloma formation was aggravated in the skin and lungs of ICAM-1-deficient mice compared with wild-type mice. Within skin granulomas of ICAM-1-deficient mice, P. acnes immunization up-regulated mRNA expression of tumor necrosis factor-α, although it failed to induce IL-10 mRNA expression in contrast to wild-type mice. Infiltration of regulatory T cells into skin granuloma was similar between wild-type mice and ICAM-1-deficient mice. P. acnes immunization induced IL-10 production by CD4(+)CD25(+)Foxp3(+) regulatory T cells in lymph nodes of wild-type mice in vivo, which was absent in regulatory T cells of ICAM-1-deficient mice. Our results indicate that ICAM-1 is imperative for inducing regulatory T cells to produce IL-10 in vivo, which would prevent granuloma formation.

Decreased tumour necrosis factor-α production by monocytes of granulomatosis with polyangiitis.

OBJECTIVES: We hypothesized that monocytes in patients with granulomatosis with polyangiitis (GPA) are polarized towards alternative activation with decreased tumour necrosis factor (TNF)-α production and that tissue-infiltrating monocytes/macrophages in granulomatous GPA lesions express CD163, a marker of alternative macrophage activation. METHOD: CD16+ monocytes in peripheral blood mononuclear cells (PBMCs) were quantified by flow cytometry. Monocytes were stimulated with increasing concentrations of lipopolysaccharide (LPS), and TNF-α production was measured at 4 and 24 h. CD163 expression in lung biopsies of patients with GPA was detected by immunohistochemistry. RESULTS: Circulating CD16+ monocytes were more frequent in GPA patients compared to controls (4.7 ± 2.8% vs. 1.9 ± 1.2%, p < 0.001). Upon activation with LPS, TNF-α production did not differ between CD16+ and CD16- monocytes. Stimulated monocytes from GPA patients produced significantly less TNF-α compared with monocytes from healthy controls (2903 ± 1320 pg/mL vs. 8335 ± 4569 pg/mL, p < 0.001). Macrophages expressing CD163 were enriched in granulomatous lung lesions of GPA patients. CONCLUSIONS: Decreased TNF-α production by circulating monocytes and CD163 overexpression by tissue monocytes/macrophages in granulomatous pulmonary lesions may suggest that monocytes/macrophages are alternatively activated in GPA.

Granulomatous Lung Diseases: A Practical Approach and Review of Common Entities.

Granulomas are frequently encountered by pathologists in all types of lung specimens and arise from diverse etiologies. They should always be reported as necrotizing or non-necrotizing, with microorganism stains performed to evaluate for infection. With attention to distribution, quality (poorly vs well-formed), associated features, and correlation with clinical, radiologic, and laboratory data, the differential diagnosis for granulomatous lung disease can usually be narrowed to a clinically helpful "short list." This review describes a practical approach to pulmonary granulomas and reviews the clinicopathological aspects of common entities, including infectious (mycobacteria, fungi) and noninfectious (hypersensitivity pneumonitis, sarcoid, and vasculitis) causes.

Asthmatic granulomatosis: a novel disease with asthmatic and granulomatous features.

RATIONALE: Severe asthma represents 5-10% of all asthma, yet remains problematic and poorly understood. Although it is increasingly recognized as consisting of numerous heterogenous phenotypes, their immunopathology, particularly in the distal airways and interstitium, remains poorly described. OBJECTIVES: To identify the pathobiology of atypical difficult asthma. METHODS: We report 10 from a total of 19 patients (17 women and 2 men) meeting asthma and severe asthma definitions, requiring daily systemic corticosteroid (CS) use, with inconsistent abnormalities on chest computed tomography scans, who underwent video-assisted thoracoscopic biopsies for further diagnosis and management. MEASUREMENTS AND MAIN RESULTS: The pathology of 10 of the 19 cases revealed small airway changes consistent with asthma (eosinophilia, goblet cell hyperplasia), but with the unexpected finding of interstitial nonnecrotizing granulomas. These patients had no evidence for hypersensitivity pneumonitis, but 70% of cases had a personal or family history of autoimmune-like disease. The 10 cases were treated with azathioprine, mycophenolic acid, methotrexate, or infliximab. Nine of 10 showed decreased CS requirements and improved or maintained FEV(1) despite lower CS doses. Of the remaining nine patients, six manifested asthmatic small airway disease, alone or in combination with alveolar septal mononuclear cells, but no granulomas, whereas three manifested other pathologic findings (aspiration, pneumonia, or thromboemboli). CONCLUSIONS: These data suggest that a subset of severe "asthma" manifests a granulomatous pathology, which we term "asthmatic granulomatosis." Although identification of this disease currently requires a thorascopic biopsy, alternative approaches to therapy lead to improvement in outcomes.

Hydroxyproline content and fibrogenesis in mouse liver and lungs during the early stages of BCG granulomatosis.

In generalized BCG granulomatosis, fibrosis starts early (on day 3) and not only around the granulomas, but also in the organs. The severity of organ fibrosis is apparently determined by the concentration of granulomas, in particular their macrophages inducing proliferation of fibroblasts in organs and granulomas as well as activation of fibrogenesis. On day 30 after infection, the degree of fibrosis in the lungs was by 6 times higher than in the liver. The increase in hydroxyproline concentration in organs in early period of infection was determined by acute stress, while on day 30 it resulted from its enhanced synthesis by granuloma fibroblasts and resident fibroblasts in organs.

TLR9 regulates the mycobacteria-elicited pulmonary granulomatous immune response in mice through DC-derived Notch ligand delta-like 4.

TLR9 activation is important for the maintenance of mycobacteria-elicited pulmonary granulomatous responses, hallmarks of protective immune responses following mycobacterial infection. However, the mechanism or mechanisms underlying this effect of TLR9 are not clear. Here, we show that Tlr9-deficient mice challenged with a Mycobacterium antigen display an altered Th17 cytokine profile, decreased accumulation of granuloma-associated myeloid DCs, and profoundly impaired delta-like 4 (dll4) Notch ligand expression. Mechanistic analysis revealed that WT bone marrow-derived DCs but not macrophages promoted the differentiation of Th17 cells from bacillus Calmette-Guérin-challenged (BCG-challenged) lung CD4+ T cells. Both lung and bone marrow DCs isolated from Tlr9-deficient mice inoculated with Mycobacterium antigen expressed lower levels of dll4 Notch ligand than the same cells isolated from WT mice. Passively immunizing WT mice with neutralizing antibodies specific for dll4 during granuloma formation resulted in larger granulomas and lower levels of Th17-related cytokines. In addition, dll4 specifically regulated Th17 activation in vitro. Together, these results suggest dll4 plays an important role in promoting Th17 effector activity during a mycobacterial challenge. Furthermore, TLR9 seems to be required for optimal dll4 expression and the regulation of Mycobacterium antigen-elicited granuloma formation in mice.

Etanercept-induced cutaneous and pulmonary sarcoid-like granulomas resolving with adalimumab.

A 59-year-old female with rheumatoid arthritis on etanercept therapy presented with a 7-cm-large subcutaneous forearm mass. Multiple smaller nodules subsequently developed on the upper and lower extremities. Except for a new cough, the patient was systemically well. Biopsy of the mass showed sarcoidal type granulomatous inflammation with nodular aggregations of non-necrotizing epithelioid histiocytes in the subcutis. A chest computed tomography (CT) scan showed mediastinal adenopathy consistent with pulmonary sarcoidosis. Etanercept was discontinued, and the patient was started on adalimumab for rheumatoid arthritis control. The cutaneous nodules fully resolved in 6 months with no additional treatment. A 4-month follow-up CT scan showed significant regression of mediastinal adenopathy. The patient has since been maintained on adalimumab therapy for 2 years with no recurrence of sarcoid-like manifestations. Biologic response modifiers targeting tumor necrosis factor alpha (TNFα) are effective treatments of chronic inflammatory conditions such as rheumatoid arthritis and psoriasis. TNFα represents a major cytokine in granuloma formation, and TNFα inhibitors are sometimes efficacious in the treatment of sarcoidosis. Paradoxically, there is a small volume of literature implicating TNFα inhibitors in the development of sarcoid-like disease. We present this case to promote the recognition of TNFα inhibitor-induced sarcoidosis and to illustrate the wide clinicopathologic differential of sarcoidal type granulomas.