Hippocampal sclerosis is associated with celiac disease type immunity in patients with drug-resistant temporal lobe epilepsy.

BACKGROUND: A prior small-scale single center study suggested an association between celiac disease (CD)-type immunity and refractory temporal lobe epilepsy (TLE) with hippocampal sclerosis (HS). The present study addresses this putative association in a large, well-characterized group of drug-resistant epilepsy (DRE) patients. These patients were grouped based on the spectrum of CD and gluten sensitivity-associated antibodies. METHODS: In this cross-sectional study, 253 consecutive adult epilepsy patients (135 females, 118 males; age 16-76 years) were categorized into three groups: (i) CD-positive group with either prior diagnosis of CD or CD-specific TG2/EmA antibodies, (ii) AGA-positive group with antigliadin antibodies (AGA) but without CD, and (iii) CD/AGA-negative group without any gluten sensitivity-associated antibodies or CD. Clinical and immunological findings were then compared among the groups. RESULTS: TLE with HS was more common in the CD-positive group compared to CD/AGA-negative group (31.8% versus 11.9%, P = 0.019). Autoimmune disorders were more common in the AGA-positive group than in the CD/AGA-negative group (P = 0.025). Considering HS lateralization; left lateralization was more common in CD-positive group compared to CD/AGA-negative group (71.4% versus 25%, P = 0.030). TG6 seropositivity did not differ among the groups (P > 0.05). CONCLUSIONS: This study provides further evidence linking TLE with HS and CD-type autoimmunity suggesting that CD-type immune response to gluten can be one potential mechanism as a disease modifier leading to DRE and HS. Understanding these immunological factors is imperative for developing immunomodulatory or dietary treatments for DRE potentially preventing HS progression.

Sclerosing mesenteritis following immune checkpoint inhibitor therapy.

PURPOSE: Sclerosing mesenteritis (SM), a fibroinflammatory process of the mesentery, can rarely occur after immune checkpoint inhibitor (ICI) therapy; however, its clinical significance and optimal management are unclear. We aimed to assess the characteristics and disease course of patients who developed SM following ICI therapy at a single tertiary cancer center. METHODS: We retrospectively identified 12 eligible adult cancer patients between 05/2011 and 05/2022. Patients' clinical data were evaluated and summarized. RESULTS: The median patient age was 71.5 years. The most common cancer types were gastrointestinal, hematologic, and skin. Eight patients (67%) received anti-PD-1/L1 monotherapy, 2 (17%) received anti-CTLA-4 monotherapy, and 2 (17%) received combination therapy. SM occurred after a median duration of 8.6 months from the first ICI dose. Most patients (75%) were asymptomatic on diagnosis. Three patients (25%) reported abdominal pain, nausea, and fever and received inpatient care and corticosteroid treatment with symptom resolution. No patients experienced SM recurrence after the completion of corticosteroids. Seven patients (58%) experienced resolution of SM on imaging. Seven patients (58%) resumed ICI therapy after the diagnosis of SM. CONCLUSIONS: SM represents an immune-related adverse event that may occur after initiation of ICI therapy. The clinical significance and optimal management of SM following ICI therapy remains uncertain. While most cases were asymptomatic and did not require active management or ICI termination, medical intervention was needed in select symptomatic cases. Further large-scale studies are needed to clarify the association of SM with ICI therapy.

Lymphocyte-Peppered Sclerotic Collagen: An Additional Histological Clue in Lichen Sclerosus, Morphea, and Systemic Sclerosis.

BACKGROUND: "Line sign," "cookie cutter sign," "square biopsy sign," "high eccrine glands sign" have been previously described in morphoea and lichen sclerosus. We found focal areas of thickened collagen bundles with lymphocytes interspersed between them in several biopsies of these conditions. MATERIALS AND METHODS: We reviewed slides of sclerosing disorders obtained from the archives of the pathology department in our hospital for the period 2013-2019. RESULTS: A total of 73 slides including 40 of lichen sclerosus, 24 of morphea, 2 of lichen sclerosus-morphea overlap, and 7 of systemic sclerosis were evaluated. Lymphocytes were noted between sclerotic collagen bundles in 46 (63%) slides, being most common in lichen sclerosus (80%, 32/40) followed by morphea (50%, 12/24), whereas it was seen in one case each of lichen sclerosus with morphea overlap (50%, 1/2) and systemic sclerosis (14.3%, 1/7). The finding was noted in the upper dermis in 20 of 32 (62.5%) slides of lichen sclerosus and in both the superficial and deep dermis in 11 (91.7%) of 12 slides of morphea. CONCLUSION: Lymphocyte-peppered sclerotic collagen may be a useful histological clue to the diagnosis of lichen sclerosus, morphea, and systemic sclerosis.

CD4+CTLs in Fibrosing Mediastinitis Linked to Histoplasma capsulatum.

Although fibrotic disorders are frequently assumed to be linked to TH2 cells, quantitative tissue interrogation studies have rarely been performed to establish this link and certainly many fibrotic diseases do not fall within the type 2/allergic disease spectrum. We have previously linked two human autoimmune fibrotic diseases, IgG4-related disease and systemic sclerosis, to the clonal expansion and lesional accumulation of CD4+CTLs. In both these diseases TH2 cell accumulation was found to be sparse. Fibrosing mediastinitis linked to Histoplasma capsulatum infection histologically resembles IgG4-related disease in terms of the inflammatory infiltrate and fibrosis, and it provides an example of a fibrotic disease of infectious origin in which the potentially profibrotic T cells may be induced and reactivated by fungal Ags. We show in this study that, in this human disease, CD4+CTLs accumulate in the blood, are clonally expanded, infiltrate into disease lesions, and can be reactivated in vitro by H. capsulatum Ags. TH2 cells are relatively sparse at lesional sites. These studies support a general role for CD4+CTLs in inflammatory fibrosis and suggest that fibrosing mediastinitis is an Ag-driven disease that may provide important mechanistic insights into the pathogenesis of idiopathic fibrotic diseases.

Increased IgG4-positive plasma cells in nodular-sclerosing Hodgkin lymphoma: a diagnostic pitfall.

AIMS: Despite increasing interest in the recently established immunoglobulin 4-related disease (IgG4-RD), its pathogenesis and aetiology remain largely unclear. Characteristic histopathological features are one of the key elements of diagnosis, including 'storiform' fibrosis, obliterative phlebitis, increased lymphoplasmacytic infiltration and increased levels of IgG4 in serum and tissue. Histopathological features of IgG4-RD are striking but not specific, and can pose a pitfall for surgical pathologists. This paper aims to determine the actual amount of IgG4+ plasma cells in nodular-sclerosing Hodgkin lymphoma (NSHL) and its potential to be misdiagnosed in routine clinical practice. METHODS AND RESULTS: IgG4+ plasma cells per high-power field (HPF) and the ratio of IgG4+ versus IgG+ plasma cells (IgG4/IgG ratio) in lymph node biopsies of 24 patients with nodular-sclerosing Hodgkin lymphoma (NSHL) were determined using immunohistochemistry and consensus scoring criteria as used for IgG4-RD. Ten lymph node biopsies with reactive follicular hyperplasia were assessed for comparison. Higher numbers of IgG4+ plasma cells (P < 0.001) were observed in NSHL versus follicular hyperplasia (mean 34 versus 8 per HPF) with a mean IgG4/IgG ratio of 0.38 versus 0.18. Five cases (21%) fulfilled the consensus criteria of IgG4-RD, with >50 IgG4+ plasma cells per HPF and an IgG4/IgG ratio of >0.4. The mean count of IgG4+ plasma cells per HPF in NSHL varied greatly (3-88) with increased numbers of IgG4+ plasma cells seen near areas of fibrosclerosis. CONCLUSIONS: Significantly higher levels of IgG4+ plasma cells are common in NSHL, emphasising the need to exclude Reed-Sternberg cells by morphology and immunohistochemistry in biopsies where IgG4-RD is suspected.

Mesial temporal lobe epilepsy with hippocampal sclerosis is infrequently associated with neuronal autoantibodies.

Mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) is characterized by its well-defined clinical profile. Limbic encephalitis is increasingly recognized as a possible etiology of adult-onset MTLE-HS, and neuronal autoantibodies have been detected in patients even without previous signs of encephalitis. The aim of this study is to analyze the frequency of specific autoantibodies in patients with MTLE-HS. A case-control study was carried out with 100 patients with MTLE-HS and 50 healthy controls. Sera samples from subjects were tested by indirect immunofluorescence assay for detection of anti-N-methyl-d-aspartate receptor (NMDA-R), anti-contactin-associated protein-like 2 (CASPR2), anti-leucine-rich glioma inactivated 1 (LGI1), anti-gamma aminobutyric acid B receptor (GABA-B-R), anti-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid 1 and 2 receptors (AMPA-1-R and AMPA-2-R), and enzyme-linked immunosorbent assay for detection of anti-glutamic acid decarboxylase 65 (GAD65). Mean age of patients and controls was 41.2 vs 42 years, and 55% vs 56% were female. Mean duration of epilepsy was 27.2 years. No neuronal autoantibodies were found in either group, except for anti-GAD65 in 3 patients and 2 controls. This study adds to the mounting evidence that, in Brazilian patients, MTLE-HS without signs and symptoms of autoimmune encephalitis may be infrequently associated with these autoantibodies. Differences regarding accuracy of used methodologies for autoantibody detection and genetic and environmental characteristics are discussed. Further works with different methodologies tested simultaneously in different populations may help clarify the incongruent study results about autoantibodies in MTLE-HS.

Unexpected Fibrosing Mediastinitis Shown on FDG PET/CT in a Patient With IgG4-Related Disease.

A 66-year-old man presented to our hospital because of abdominal pain for 5 days. A contrast abdominal CT raised the possibility of pancreatic carcinoma. FDG PET/CT showed increased FDG accumulation not only in the pancreas and the retroperitoneum, but also in the posterior mediastinum, which was not typical of pancreatic carcinoma. The patient was subsequently diagnosed having immunoglobulin G4-related disease following the histopathologic examination.

Progressive hippocampal sclerosis after viral encephalitis: Potential role of NMDA receptor antibodies.

PURPOSE: Survivors of viral encephalitis can develop refractory epilepsy and hippocampal sclerosis. Both the initial infectious insult and the secondary effects of recurrent seizures have been implicated in chronic disease progression. Recently, post-infectious autoimmunity, involved in acute relapses, has also been proposed as a pathomechanism for chronic disease progression. Our case series suggests a potential role of antibodies against the N-methyl-d-aspartate receptor (NMDAR) in chronic inflammatory disease beyond acute manifestations. METHODS: Retrospective chart review of four patients with epilepsy, hippocampal sclerosis following viral encephalitis and NMDAR-antibodies in CSF. RESULTS: The four patients were female, developed hippocampal sclerosis (in 3/4 in a step-wise progression) after Herpes simplex or Varicella zoster virus encephalitis and harboured immunoglobulin G antibodies against the NMDAR in their CSF. Two patients were treated with short-term immunosuppression but did not benefit. CONCLUSION: This case series presents the first tentative evidence in support of chronic autoimmune inflammation driving disease progression after viral encephalitis beyond the known acute immune-mediated relapses. The anecdotal nature of the data does not, however, permit conclusive judgement on causality. Should our findings be replicated in larger cohorts, the treatment of post-infectious epilepsy could potentially be expanded to include immunosuppressive strategies in antibody-positive cases.

[IgG4-related sclerosing disease of the larynx]. / IgG4-sviazannaia skleroziruiushchaia bolezn' gortani.

IgG4-related sclerosing disease of the larynx (IgG4-SD) is a recently described immunodependent systemic pathology characterized by diffusive or focal inflammatory infiltration of the affected organs and tissues by plasma cells expressing IgG4; it is accompanied by the subsequent development of obliterative phlebitis and fibrosclerosis associated with the increase of the serum IgG4 level. According to the recently published materials, the disease can also develop in the respiratory system. The present article describes the first documented case of IgG4-related sclerosing disease with the isolated lesion of the larynx. The diagnosis was established based on the results of the comprehensive examination that made it possible to exclude systemic lesions, to determine the IgG4 level in the serum, and to carry out the immunohistochemical study of the histological preparations stained for the detection of IgG4-releasing plasmocytes. After verification of the diagnosis, the patient underwent a course of systemic hormonal therapy that resulted in the stable clinical and roentgenological remission of the disease that persists up to the present time.

IL-33-Mediated Expansion of Type 2 Innate Lymphoid Cells Protects from Progressive Glomerulosclerosis.

Innate lymphoid cells (ILCs) have an important role in the immune system's response to different forms of infectious and noninfectious pathologies. In particular, IL-5- and IL-13-producing type 2 ILCs (ILC2s) have been implicated in repair mechanisms that restore tissue integrity after injury. However, the presence of renal ILCs in humans has not been reported. In this study, we show that ILC populations are present in the healthy human kidney. A detailed characterization of kidney-residing ILC populations revealed that IL-33 receptor-positive ILC2s are a major ILC subtype in the kidney of humans and mice. Short-term IL-33 treatment in mice led to sustained expansion of IL-33 receptor-positive kidney ILC2s and ameliorated adriamycin-induced glomerulosclerosis. Furthermore, the expansion of ILC2s modulated the inflammatory response in the diseased kidney in favor of an anti-inflammatory milieu with a reduction of pathogenic myeloid cell infiltration and a marked accumulation of eosinophils that was required for tissue protection. In summary, kidney-residing ILC2s can be effectively expanded in the mouse kidney by IL-33 treatment and are central regulators of renal repair mechanisms. The presence of ILC2s in the human kidney tissue identifies these cells as attractive therapeutic targets for CKD in humans.

Idiopathic Mediastinal Fibrosis: a Systemic Immune-Mediated Disorder. A Case Series and a Review of the Literature.

Mediastinal fibrosis is a rare disease characterised by fibrous proliferation in the mediastinum. It can be idiopathic or secondary to several conditions such as infections and malignancies. Anecdotal reports have described idiopathic mediastinal fibrosis (IMF) in association with other fibro-inflammatory or autoimmune diseases. We report nine new IMF cases recently seen at our Fibro-Inflammatory Disease Clinic and reviewed the IMF cases reported in the English language literature throughout 2006-2016. The purposes of our literature search were to assess the frequency of the association between IMF and other immune-mediated disorders and to analyse which disorders most often coexist with IMF. Of our nine IMF cases, one was associated with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis, one with large-vessel arteritis, three with idiopathic retroperitoneal fibrosis (one of which was IgG4-related), one with pancreatitis and one with IgG4-related seminal vesicle involvement. The remaining two cases, in which IMF was not associated with any other disease, were both classifiable as IgG4-related. The literature review showed that, of the 84 IMF cases identified, 27 (32 %) were associated with other idiopathic autoimmune or fibro-inflammatory disorders, particularly small-vessel vasculitis, Behçet disease, retroperitoneal fibrosis and other conditions belonging to the IgG4-related disease spectrum. Based on our own data and the literature review, we conclude that IMF is often associated with other autoimmune or fibro-inflammatory diseases; therefore, its clinical management requires an accurate screening of associated conditions. Immune-mediated mechanisms may be shared by these disorders.

IGG4 Disease And Slerosing Aortitis.

INTRODUCTION: IgG4-related disease (IgG4-RD) is an immune- -mediated fibro-inflammatory condition with unknown etiology that can affect various organs. Although its prevalence is still unknown, it appears to be more frequent in adult males. Cardiovascular manifestations are rare and can include idiopathic retroperitoneal periaortic fibrosis, inflammatory aortic aneurism, inflammatory periarteritis and inflammatory pericarditis. Vascular involvement is a well-recognized feature and large vessel commitment, especially the aorta, can be the only manifestation of the disease. The gold standard diagnosis is histological. METHODS: A 47-year-old man presented rupture of two aortic aneurysms: one thoracic and one abdominal, and underwent surgical correction. A segment of the aorta artery wall measuring 3x2x0.5cm, exhibited smooth intimate and white vinous adventitia, medium tunic was white, through firm tissue with loss of elasticity. RESULTS: In addition to heterogenous collagenation with destruction of the elastic network of the aortic mediae tunica, there was fibrin deposition and neutrophil overlap. Lymphoid follicles with reactive germinate centers were along the tunica media and adventitia, without phenotype of endothelitis and absence of either macrophages and Langerhans cells (CD1a). Plasmocytes showed immunopositivity to IgG4, with heterogeneous and well defined localization, supporting the diagnosis of igG4 Disease. Serological studies showed negativity for vasculitis, hereditary connective tissue diseases were not component of the clinical set and normal serum IgG4 concentration was determined. CONCLUSION: Few cases of involvement of large vessels by IgG4- -RD have been reported in literature. Serum IgG4 concentration may be normal in one third of patients. In this case, IgG4 immunostaining was crucial for the diagnosis of IgG4-RD aortitis, together with the hyaline destruction of the tunica media (ESP 2015 / Aagaimy 2013). There is still no clinical knowledge for the treatment and monitoring of the involvement of large vessels by IgG4-RD.

Neuronal autoantibodies in mesial temporal lobe epilepsy with hippocampal sclerosis.

OBJECTIVE: Our aim was to investigate the prevalence of neuronal autoantibodies (NAbs) in a large consecutive series with mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) and to elucidate the clinical and laboratory clues for detection of NAbs in this prototype of frequent, drug-resistant epilepsy syndrome. METHODS: Consecutive patients diagnosed with MTLE fulfilling the MRI criteria for HS were enrolled. The sera of patients and various control groups (80 subjects) were tested for eight NAbs after ethical approval and signed consents. Brain tissues obtained from surgical specimens were also investigated by immunohistochemical analysis for the presence of inflammatory infiltrates. The features of seropositive versus seronegative groups were compared and binary logistic regression analysis was performed to explore the differentiating variables. RESULTS: We found antibodies against antigens, contactin-associated protein-like 2 in 11 patients, uncharacterised voltage-gated potassium channel (VGKC)-complex antigens in four patients, glycine receptor (GLY-R) in 5 patients, N-methyl-d-aspartate receptor in 4 patients and γ-aminobutyric acid receptor A in 1 patient of 111 patients with MTLE-HS and none of the control subjects. The history of status epilepticus, diagnosis of psychosis and positron emission tomography or single-photon emission CT findings in temporal plus extratemporal regions were found significantly more frequently in the seropositive group. Binary logistic regression analysis disclosed that status epilepticus, psychosis and cognitive dysfunction were statistically significant variables to differentiate between the VGKC-complex subgroup versus seronegative group. CONCLUSIONS: This first systematic screening study of various NAbs showed 22.5% seropositivity belonging mostly to VGKC-complex antibodies in a large consecutive series of patients with MTLE-HS. Our results indicated a VGKC-complex autoimmunity-related subgroup in the syndrome of MTLE-HS.

Unilateral orbital mass as an unusual presentation of IgG4-related disease.

IgG4-related diseases are a recently recognized systemic syndrome characterized by mass-forming lesions, in mainly exocrine tissue, that consist of lymphoplasmacytic infiltrates and sclerosis, which may mimic malignant neoplasm due to clinical and imaging features. We report an unusual case of a 62-year-old woman who presented with a left orbital mass, which histologically revealed to be an IgG4-sclerosing disease.

Lymphocyte subsets contribute to the degree of lobulitis and ductitis in sclerosing lymphocytic lobulitis of the breast.

AIMS: Sclerosing lymphocytic lobulitis (SLL) of the breast is characterised by lymphocytic lobulitis, ductitis, vasculitis and dense keloidal fibrosis with epithelioid fibroblasts. However, the subsets of the infiltrating lymphocytes and their contribution to disease progression have not been fully explored. METHODS: CD20, CD3, CD4, CD8 and regulatory T (Treg) lymphocytes were evaluated in the epithelial and vascular areas in SLL. The relationship between the lymphocyte subset in different regions and the degree of inflammation was analysed. RESULTS: Lymphocytic infiltration was mainly located in peri-lobular, peri-ductal and peri-vascular areas. No significant differences between CD20 and CD3 lymphocytes were found in peri-epithelial areas. However, there were more intra-ductal/lobular epithelial CD3 than CD20 lymphocytes (p<0.001). For T lymphocyte subsets, more CD4 than CD8 lymphocytes were found in the peri-lobular/vascular regions (p≤0.026); but an opposite trend was seen in the intra-ductal/lobular regions (p<0.001). In the peri-lobular/vascular regions, generally, different lymphocyte subsets correlated with each other. Interestingly, in the peri-ductal region, only CD4 lymphocytes showed significant correlations with all other subsets (p≤0.020). Regarding their relationship with the degree of inflammation, significant positive correlations were observed for all subsets in peri-vascular/lobular regions (p≤0.045). Only regulatory T cells, but not the others, at the peri-ductal region showed significant correlation with the degree of inflammation at all three regions (p≤0.014). CONCLUSIONS: In addition to B lymphocyte subsets, T lymphocyte subsets could be involved differently in SLL. CD4 lymphocytes may have a pivotal role in recruiting other subsets to the inflamed site, and triggered the cascade of inflammatory changes resulting in fibrosis.

Fibrosing mediastinitis complicating prior histoplasmosis is associated with human leukocyte antigen DQB1*04:02 - a case control study.

BACKGROUND: Fibrosing mediastinitis (FM) is an idiosyncratic reaction to infection with Histoplasma capsulatum with a prevalence of 3:100,000 people infected. The rarity of post-histoplasmosis fibrosing mediastinitis (PHFM) in areas where H. capsulatum is endemic suggests that an abnormal immunological host response may be responsible for the development of fibrosis. Our group previously reported an association between subjects with PHFM and human leukocyte antigen (HLA)-A*02. We sought to confirm or extend those findings with application of high resolution HLA typing in a cohort of subjects with PHFM. METHODS: High-resolution HLA typing was performed on DNA samples from a new cohort 34 patients with PHFM. Control cohorts included 707 subjects from the "European American" subset of the National Marrow Donor Program(®) (NMDP) and 700 subjects from Dialysis Clinic, Inc. (DCI). The carriage frequencies of the HLA alleles identified in the PHFM, NMDP, and DCI cohorts were calculated and then all were compared. RESULTS: We found an increase in the carriage frequency of HLA-DQB1*04:02 in PHFM subjects relative to the controls (0.15 versus 0.07 in DCI and 0.05 in NMDP; p = 0.08 and 0.03). Multiple logistic regression showed that DQB1*04:02 was statistically significant (p = 0.04), while DQB1*03:02 and C*03:04 had point estimates of OR > 1, though they did not reach statistical significance. The HLA-A*02 association was not replicated. CONCLUSIONS: HLA-DQB1*04:02 is associated with PHFM, which supports the premise that an aberrant host immune response contributes to the development of PHFM.

Immunoglobulin G4-related paratesticular fibrous pseudotumor and retroperitoneal fibrosis: a case report.

A 46-year-old man with a past history of retroperitoneal fibrosis was admitted with an enlarged, hard right testis. The paratesticular lesion showed heterogeneous hypoechogenicity on ultrasonography, low signal intensity on T1- and T2-weighted magnetic resonance imaging (MRI), and lack of diffusion restriction on diffusion-weighted MRI. Following steroid treatment, the paratesticular mass was decreased in size on follow-up computed tomography. The radiologic and clinical features are recognized as a manifestation of immunoglobulin G4-related sclerosing disease involving the paratesticular region and retroperitoneum.

Focal autoimmune pancreatitis and chronic sclerosing sialadenitis mimicking pancreatic cancer and neck metastasis.

Type 1 autoimmune pancreatitis (AIP) or chronic sclerosing sialadenitis (Küttner's tumour) is an uncommon disorder that has recently been confirmed as an IgG4-related disease. Here, we describe a rare case of a 53-year-old male patient who primarily presented with pancreatic body mass, left neck mass and several lumps in his lower lip mimicking pancreatic cancer (PC) and neck metastasis. The patient underwent pancreatic body mass and labial gland lumps resection as well as an ultrasound-guided biopsy of the left neck mass. He was diagnosed with IgG4-related focal type of AIP (f-AIP) and Küttner's tumour by immunohistochemistry. The patient responded well to corticosteroid therapy and remains healthy with no signs of recurrence at one year follow-up. The differentiation of f-AIP from PC is very important to avoid unnecessary pancreatic resection.

Beyond allergy: the role of mast cells in fibrosis.

Mast cells are tissue-bound cells of the innate immune system which are well known for immunoglobuline (Ig)E-triggered degranulation in allergic reactions. More recently, an important role of mast cells has been described in chronic inflammatory and autoimmune disorders which are often associated with fibrosis or sclerosis. Innate immune receptors such as Fc-, toll-like- or NOD-like receptors stimuli can trigger mast cell degranulation and enhance immunological danger signals. Whereas fulminant degranulation of mast cell vesicles is observed in anaphylaxis, piecemeal degranulation or transgranulation are mechanisms for a slower release of their granula. A cocktail of cytokines, growth factors and proteoglycans is produced and stored in granula of mast cells. Mast cells are a substantial reservoir of both preformed inflammatory factors (i.e., TNF-alpha and IL-17) and factors that can trigger a profibrotic, Th-2-polarised inflammation (i.e., IL-4 and IL-10). In systemic sclerosis, mast cell vesicles are the main source of transforming growth factor (TGF)-beta. Cell-to-cell contact between mast cells and fibroblasts occurs in the affected tissue, supporting the hypothesis that transgranulation might be an important mechanism in fibrosis. The direct release of proteoglycans such as hyaluronic acid into the interstitial space is a further stimulus for matrix remodelling. Mast cell hyperactivity has also been demonstrated in primary fibrotic disorders such as lung, cardiac or renal fibrosis. The exact trigger for mast cell degranulation however is not known. Notwithstanding, at a very early time point of fibrosis, mast cell inhibition by stabilisers or blockage of the tyrosine kinase receptor c-kit by masitinib could be a therapeutic option.