Sarcoidosis and molecular mimicry--important etiopathogenetic aspects: current state and future directions

Angular cheilitis-an oral disease with many facets

Cheilitis is a common inflammatory disorder of the vermillion and adjacent skin of the lips. A special type is angular cheilitis. The disease has a mixed etiology, mostly with bacterial and fungal components. Angular cheilitis may be a clinical sign of an underlying disease. It has two age peaks: one during childhood and another in adults. It becomes more frequent with aging. Clinical presentation, differential diagnoses, and treatment are discussed. Angular cheilitis is of importance in primary care of patients, in geriatrics, dentistry, pediatrics, internal medicine, and in dermatology.

First reported case of erythrodermic sarcoidosis with systemic involvement during vaccination for Covid-19

Post-vaccinal and parainfectious activation of the immunity with subsequent development of a certain immunological/skin-immunological disease isn’t rare in the clinical practice. This concept is mentioned in relation to molecular/antigenic mimicry. To this day, the pathogenesis of sarcoidosis and sarcoid-type reactions remains a mystery. Moreover, they can be a warning sign of changes in tissue homeostasis, whether it is infectious, non-infectious-immunological, tumor-related, etc. We present a rare form of erythrodermic sarcoidosis with massive systemic involvement (pericarditis, supraventricular tachycardia, hepatitis, iritis/iridocyclitis, pulmonary fibrosis/bihilar lymphadenopathy, and arthritis) developed after receiving the ChadOx1-S vaccine for Covid-19. Systemic immunosuppressive therapy with Methylprednisolone was introduced according to a scheme (in a reduction mode with an initial dose of 40 mg/day intravenously) in combination with: topical Pimecrolimus 1% cream twice a day. Rapid improvement of the symptoms was observed within the first two days of treatment. According to the references in the scientific literature, the presented patient turns out to be the first case of erythrodermic sarcoidosis (with systemic involvement), described as a side effect after vaccination and/or administration of a certain medicinal form.

Identification of autoimmune markers in pulmonary tuberculosis

Introduction

Pathogenesis of many autoimmune diseases is mainly promoted by poorly regulated and/or wrong targeted immune response to pathogens including M. tuberculosis. Autoimmunity is one of the processes with are characteristics of tuberculosis (Tbc). The aim was to determine the autoimmune clinical and immunological features in patients with pulmonary Tbc.

Materials and methods

A prospective comparative study was performed in 2017 - 2019 with the inclusion of 46 patients with Tbc. The trigger factors and clinical manifestations, autoantibodies, peripheral blood B cell subsets were stained with fluorochrome-conjugated monoclonal antibodies. 40 healthy volunteers in the control group, were matched for age with no chronic diseases, contacts with TB patients and changes in their laboratory parameters. A statistical analysis was done with GraphPad Prism 6, Statistica 10 (Statsoft) and MedCalc - version 18.2.1 values.

Results

There were no significant ASIA triggers in Tbc patients and control group. 21.1% of Tbc patients had a high level of a rheumatoid factor and in 47.4% complement system factor C3 was high; anti-MCV was detected in 60.7% of Tbc patients. Relative and absolute frequencies of "naïve" Bm1 cells and eBm5 were significantly decreased and activated pre-germinal-center Bm2' cells were significantly increased in Tbc patients. The CD24++CD38++ B cells were increased in Tbc vs control group (10.25% vs 5.42%), p < 0.001, and 19 cell/1μL (10; 290 vs 11 cell/1μL (6; 20), p = 0.029, respectively). The frequency of CXCR3+CCR4- Tfh1 cells was significantly lower in Tbc vs control one (26.52% vs. 31.00%, p = 0.004), while CXCR3-CCR4+ Tfh2 cells were increased in Tbc (20.31% vs. controls (16.56%, p = 0.030). The absolute numbers of Tfh1 cells were decreased in the Tbc vs. control (24 cell/1μL vs. 37 cell/1μL p = 0.005).

Conclusion

The results of our study showed that the detection of a rheumatoid factor, the components of complement system and anti-MCV in complex with alterations in B cells and follicular Th cell subsets may indicate a presence of autoimmunity in the pathogenesis of tuberculosis, but they are not specific. The indicators of autoimmune-related provide new opportunities in the Tbc treatment.

Detection of Anti-Vimentin Antibodies in Patients with Sarcoidosis

There is a need to further characterize the antibody response to vimentin in relation to its possible involvement in pathogenicity of sarcoidosis and other lung disorders. Objectives: We investigated serum samples from patients with sarcoidosis, healthy controls and controls with other non-infectious lung diseases., to evaluate levels and frequency of these antibodies. Materials and methods: A retrospective-prospective comparative study was performed in the years 2015–2019. Sera from 93 patients with sarcoidosis, 55 patients with non-infectious lung diseases and 40 healthy subjects was examined for presence of autoantibodies to mutated citrullinated vimentin (anti-MCV). Patients with elevated anti-MCV levels were tested for antibodies to a cyclic citrullinated peptide (anti-CCP) and citrullinated vimentin (anti-Sa). In all cases ELISA assays was used. The results were considered statistically significant at p-value less than 0.05. Results of the study: The high concentrations of anti-MCV antibodies were more frequent in patients with sarcoidosis (40.9% of the cases, 38/93), compared to the control groups (23.6% and 25.0% of cases, respectively). In sarcoidosis, clinical symptoms similar to the autoimmune pathology were described. A moderate positive correlation between the anti-MCV and anti-Sa antibodies (r = 0.66) was found in 13 patients with sarcoidosis. There was no significant difference between the levels of the anti-MCV and the anti-CCP in patients with non-infectious lung diseases and the healthy control group. Conclusion: Antibodies to citrullinated cyclic peptides are not significant in the pathogenesis of sarcoidosis and other investigated pulmonary diseases (COPD, granulomatosis with polyangiitis, alveolitis) and based on their low concentration, it can be assumed that citrullination and modification of vimentin is not a key factor in the development of an autoimmune response in patients with sarcoidosis.

New laboratory criteria of the autoimmune inflammation in pulmonary sarcoidosis and tuberculosis

Sarcoidosis and tuberculosis have many clinical and laboratory similarities, which allowed researchers to assume the presence of common pathogenetic mechanisms in the development of both diseases. Recently, much attention has been paid to investigate the autoimmune origins in these pathologies. The aim of this study is to find out the characteristics of the autoinflammatory immune response in sarcoidosis and tuberculosis. In patients with sarcoidosis (n = 93), tuberculosis (n = 28), and in healthy donors (n = 40), the serum anti-MCV concentration was measured by ELISA, and B cell subpopulations were analyzed by flow cytometry. Based on the results obtained, the formula ([B-naïve%]\[B-memory%]) * ([B-CD38%] + [B-CD5%]) / [anti-MCV] was described. The increase in the calculated index by more than 5 units with a sensitivity of 80.00% and a specificity of 93.10% (AUC = 0.926) suggest the presence of the autoimmune component, which is more typical for sarcoidosis, rather than tuberculosis patients and may serve as a diagnostic criterion.

Granulomatous slack skin mycosis fungoides developing simultaneously with sarcoid-like lesions in a patient with repeated anabolic injections in the past?

We present a 32-year-old man with successful treatment and remission of mycosis fungoides of both axillae in 2016 after PUVA therapy and systemic and local administration of corticosteroids. Subsequently, in 2017, the patient also achieved remission of a T-cell CD 30 positive, ALK-1 negative large-cell lymphoma of a retroperitoneal and inguinal lymph node after chemotherapy and radiotherapy. One year later, in 2018, the patient presented to our clinic with progression of skin lesions in both axillary areas and the appearance of а tumor in the right gluteal region.Dermatological examination showed livid-to-erythematous, partly sclerotic plaques in the right inguinal area, cutis laxa-like plaque formations in the right axillary region with similar but less-developed changes in the left axillary fold, a solitary subcutaneous tumor formation affecting the entire right gluteal region, and enlarged, palpable lymph nodes in the right para-axillary area. Biopsies were obtained from an axillary lesion and the surgically removed axillary lymph nodes, and histological examination revealed changes of granulomatous slack skin in the axilla and reactive inflammatory changes in the lymph nodes. Histology of gluteal tissue showed a "foreign body" type of reaction with sarcoid-like features, where the patient in the past have been injected with anabolic and steroidal drugs. Herein we describe a patient with simultaneous occurrence of granulomatous slack skin type mycosis fungoides and a sarcoid-like reaction. The question remains open whether this represents the so-called sarcoidosis-lymphoma syndrome or, more likely, granulomatous slack skin MF associated with a sarcoid-like reaction of "foreign body" type. The possibility that disturbance of tissue homeostasis by incorporation of certain adjuvants within injections (for example) in the past might have been an inducer of cutaneous T cell lymphoma and sarcoidosis/sarcoid like lesions seems reasonable but also speculative.

T-cell immunology in sarcoidosis: Disruption of a delicate balance between helper and regulatory T-cells

PURPOSE OF REVIEW

Although the aetiology of sarcoidosis is not yet completely understood, immunological changes within the T-cell compartment are characteristic for an exaggerated antigen-driven immune response. In this review, we describe the most recent findings on T-cell subset responses and regulation in sarcoidosis. We discuss how future immunological research can advance the field to unravel pathobiological mechanisms of this intriguingly complex disease.

RECENT FINDINGS

Research into the field of T-cell plasticity has recently challenged the long-held T helper type 1 (Th1) paradigm in sarcoidosis and striking parallels with autoimmune disorders and common variable immunodeficiency were recognized. For instance, it was demonstrated that Th17.1-cells rather than Th1-cells are responsible for the exaggerated IFN-γ production in pulmonary sarcoidosis. Furthermore, impaired regulatory T-cell function and alterations within the expression of co-inhibitory receptors that control T-cell responses, such as PD-1, CTLA-4 and BTNL2, raise new questions regarding T-cell regulation in pulmonary sarcoidosis.

SUMMARY

It becomes increasingly clear that Th17(.1)-cells and regulatory T-cells are key players in sarcoidosis T-cell immunology. New findings on plasticity and co-inhibitory receptor expression by these subsets help build a more comprehensive model for T-cell regulation in sarcoidosis and will finally shed light on the potential of new treatment modalities.

Crohn's disease and sarcoidosis in siblings: follow-up of a published report with a new case and brief review of the literature

Reported in 1971 were the cases of three brothers, two of whom had developed sarcoidosis and the third Crohn's disease. That now presented concerns one brother who, 50 years after the diagnosis and successful treatment of his sarcoidosis, was found incidentally, at colonoscopy performed to exclude malignancy, to have Crohn's colitis in the absence of any symptoms attributable to this. The report concludes with a brief review of the literature.

Multisystemic Sarcoidosis Presenting as Pretibial Leg Ulcers

Sarcoidosis is a multisystemic disease of unknown etiology. Up to 30% of patients develop cutaneous manifestations, either specific or nonspecific. Ulcerating sarcoidosis leading to leg ulcers is a rare observation that may lead to confusions with other, more common types of chronic leg ulcers. We report the case of a 45-year-old female patient with chronic multisystemic sarcoidosis presenting with pretibial leg ulcers. Other etiology could be excluded. Histology revealed nonspecific findings. Therefore, the diagnosis of nonspecific leg ulcers in sarcoidosis was confirmed. Treatment consisted of oral prednisolone and good ulcer care. Complete healing was achieved within 6 months. Sarcoidosis is a rare cause of leg ulcers and usually sarcoid granulomas can be found. Our patient illustrates that even in the absence of sarcoid granulomas, leg ulcers can be due to sarcoidosis.

Treatment with Doxycycline of Generalized Annular Elastolytic Giant Cell Granuloma Associated with Borrelia burgdorferi Infection

This is a case of generalized annular elastolytic giant cell granuloma (AEGCG) associated with borrelia infection and genes of p-30, p-31, p-39. A possible cross-mediated reaction from the T-cell type which might have induced the AEGCG is discussed from the concept of "heat-shock proteins (HSPs) and molecular mimicry".

Histologic features of granulomatous skin diseases. Part 1: Non-infectious granulomatous disorders

Granulomatous disorders affecting the skin belong to a heterogeneous group of diseases. With the exception of granulomas induced by infectious agents or foreign bodies, the etiopathogenesis of granulomatous disorders is still poorly understood. The knowledge of histopathologic changes is of great importance for understanding clinical presentation and disease course.

The "mystery" of cutaneous sarcoidosis: facts and controversies

The reason why the cutaneous form of sarcoidosis is well known in the literature is because of its spectrum of manifestations granting it the fame of a Great Imitator. The mystery shrouding the pathogenesis of this rare cutaneous disease is still there (in spite of the fundamental progress of the various diagnostic methods in current day medicine). The production of the morphological substrate - the epithelioid cell granuloma - which is considered to be characteristic of skin sarcoidosis, could, however, also be the end result of a reaction to i) various specific infectious agents such as Leishmaniasis cutis, coccidioidomycosis, etc., ii) certain residual bacterial or other mycobacterial antigens which, at the moment of setting the diagnosis are - by definition - non-infectious but still immunogenic, as well as iii) different tumor antigens in lesional tissue or other location. Often, differentiating between sarcodiosis and a sarcoid-like reaction, based on the updated criteria for cutaneous sarcoidosis, is problematic to downright impossible. A future characterization of the genetic signature of the two conditions, as well as the implementation of additional mandatory panels for i) the identification of certain infectious or ii) non-infectious but immunogenic and iii) tumor antigens in the epithelioid cell granuloma (or in another location in the organism), could be a considerable contribution to the process of differentiating between the two above-mentioned conditions. This will create conditions for greater accuracy when setting the subsequent therapeutic approaches.

Chitotriosidase in the Pathogenesis of Inflammation, Interstitial Lung Diseases and COPD

As a member of 18 glycosyl hydrolase (GH) family, chitotriosidase (Chitinase 1, CHIT1) is a true chitinase mainly expressed in the differentiated and polarized macrophages. CHIT1 is an innate immune mediator that digests the cell walls of chitin-containing eukaryotic pathogens, such as fungi. However, CHIT1 is dysregulated in granulomatous and fibrotic interstitial lung diseases characterized by inflammation and tissue remodeling. These include tuberclosis, sarcoidosis, idiopathic pulmonary fibrosis, scleroderma-associated interstitial lung diseases (SSc-ILD), and chronic obstructive lung diseases (COPD). CHIT1 serum concentration correlates with the progression or the severity of these diseases, suggesting a potential use of CHIT1 as a biomarker or a therapeutic target. Recent studies with genetically modified mice demonstrate that CHIT1 enhances TGF-β1 receptor expression and signaling, suggesting a role in initiating or amplifying the response to organ injury and repair. This additional CHIT1 activity is independent of its enzymatic activity. These studies suggest that CHIT1 serves a bridging function; it is both an innate immune mediator and a regulator of tissue remodeling. This review will focus on recent data linking CHIT1 to the pathogenesis of inflammation, interstitial lung disease, and COPD.

Sarcoidosis, cancer and molecular mimicry

Molecular mimicry seems to be the most important factor for the heterogeneous clinical presentation and the immunopathogenesis of sarcoidosis. Molecular mimicry may occur as a result of altered activity of oncogenes. This can lead to crossed-type mediated body reactions targeting structurally similar sections or regions from the tissue homeostasis. Available data suggest that structural analogy between tissue and foreign or de novo-appearing peptides is not always reliable. Nevertheless, lack of amino acid identity between the tissue and the de novo-generated tumour antigens does not exclude the phenomenon of molecular mimicry as the major generator of sarcoidosis. There is growing evidence of the mimicry phenomena, caused not only by the similarity between the amino acids but also between the elements which connect segments in the immunological cascade and which may also be affected by external factors. Molecular mimicry may occur between two identified peptides having similar antigenic surfaces (transitory or not), in the absence of a primary homology in amino acid sequence. As far as tumour antigens are concerned, a structural analogy to the de novo-appearing tumour antigens is more likely than transitory imitation resulting from the additional interference of other physical forces. Further research should be performed to confirm, or reject, the transitory imitation thesis or hypothesis.

High rate of cardiac sarcoidosis presenting with cutaneous plaque type sarcoidosis in 18F-fluorodeoxyglucose positron emission tomography-computed tomography: a case series

Introduction

Myocardial sarcoidosis is known as a significant complication of sarcoidosis, but Holter electrocardiographic monitoring or echocardiograms might not be sensitive enough to detect cardiac involvement. While gallium scintigraphy has been recommended, ¹⁸F-fluorodeoxyglucose positron emission tomography-computed tomography might be more sensitive to detect sarcoidosis.

Case presentations

This report comprises the cases of 12 Japanese patients. Two were male, and ten were female. Their age range was between 32 and 93 years. The average age of the patients was 63. We found internal involvement of sarcoidosis in eight (89%) of nine patients by positron emission tomography-computed tomography and in two (67%) of three patients by gallium scintigraphy. Myocardial sarcoidosis was detected in four (33%) of twelve patients, and specifically in three (75%) of four facial multiple plaque type sarcoidosis patients.

Conclusion

The myocardial lesions detected by positron emission tomography-computed tomography could not be detected with conventional electrocardiogram or echogram. Positron emission tomography-computed tomography can detect sarcoid lesions of the whole body and is useful for the follow up of patients. We recommend positron emission tomography-computed tomography for those patients having cutaneous sarcoidosis, especially facial multiple plaque type sarcoidosis.

Molecular mimicry in cutaneous autoimmune diseases

The emulation of characteristics of a different organism to gain biological advantage is a common phenomenon in nature, described and defined with the term “mimicry” in the second half of the 19^th century. In the last decades, mimicry at molecular level has been evidenced as a method used by several pathogen microrganisms to control metabolic functions of infected cells and elude host’s immune system. Because of molecular mimicry, immune reactions against microbial molecules can turn against the mimicked self-molecules in predisposed subjects, leading to autoimmunity. This pathogenic mechanism, which gives a possible explanation for the specific epidemiological and chronological association between some infections and some autoimmune diseases, is well known and verified in many fields of medicine, but not adequately studied in dermatology: experimental data are available only for leprosy, atopic dermatitis, Behçet’s disease, Vogt-Koyanagi-Harada syndrome and systemic erythematous lupus, while for few other diseases its role is hypothetical or suggested on the basis of single, small experiments or anecdotal reports. An overview of available data and hypotheses about the role of molecular mimicry in autoimmune cutaneous diseases is presented here, together with the perspectives offered by the use of bioinformatics and the personal experience of the author in this field.