[Pathogenesis of hidradenitis suppurativa/acne inversa]

Hidradenitis suppurativa/acne inversa (HS) has a multifactorial pathogenesis. In addition to a sporadic form, a familial form is reported in around 40% of patients, for whom an autosomal dominant (AD) inheritance with reduced gene penetrance is assumed. The phenotype of the disease with inflammatory nodules, abscesses and secreting sinus tracts suggests an infectious origin, but the exact role of the bacteria detected in HS pathogenesis remains unclear. Smoking and metabolic syndrome are regarded as important trigger factors in HS, with obesity and hormonal changes playing a pathogenic role in the latter. Ultimately, Toll-like receptors, antimicrobial peptides, immune cells and key cytokines are involved in the excessive inflammatory reaction of HS and are also the targets of future therapies.

Computer-based detection of depression and dementia in spontaneous speech

Introduction

There is a significant relation between old-age depression and subsequent dementia in patients aged 50. This supports the hypothesis of old-age depression being a predictor, and possibly a causal factor, of subsequent dementia. The number of people aged 60 years and over has tripled since 1950, reaching 16% in 2050, leading to new medical challenges. Depression is the most common mental disorder in older adults, affecting 7% of the older population. Dementia is the second most common with about 5% prevalence worldwide, but it is the first leading cause of disease burden.

Objectives

Early detection and treatment is essential in promoting remission, preventing relapse, and reducing emotional burden. Speech is a well established early indicator of cognitive deficits. Speech processing methods offer great potential to fully automatically screen for prototypic indicators of both dementia and depressive disorders.

Methods

We present two different methods to detect pathological speech with artificial neural networks. We use both deep architectures, as well as more traditional machine learning approaches.

Results

The models developed using a two-stage deep architecture achieved 59% classification accuracy on the test set from DementiaBank. Our CNN system achieved the best classification accuracy of 63.6% for dementia, but reaching 70% for depressive disorders on the test set from Distress Analysis Interview Corpus.

Conclusions

These methods offer a promising classification accuracy ranging from 63% to 70%, applicable in an innovative speech-based screening system.

Aetiology and pathogenesis of hidradenitis suppurativa

Hidradenitis suppurativa (HS) is a chronic inflammatory disorder. Patients develop inflamed nodules and abscesses and, at later stages of disease, epithelialized tunnels and scars in skinfolds of axillary, inguinal, gluteal and perianal areas. Quality of life is affected due to severe pain, purulent secretion, restricted mobility and systemic involvement. Genetics and lifestyle factors including smoking and obesity contribute to the development of HS. These factors lead to microbiome alteration, subclinical inflammation around the terminal hair follicles, and infundibular hyperkeratosis, resulting in plugging and rupture of the follicles. Cell-damage-associated molecules and propagating bacteria trigger inflammation and lead to massive immune cell infiltration that clinically manifests as inflamed nodules and abscesses. The immune system plays a key role also in the progression and chronification of skin alterations. Innate proinflammatory cytokines (e.g. interleukin-1β and tumour necrosis factor-α), mediators of activated T helper (Th)1 and Th17 cells (e.g. interleukin-17 and interferon-γ), and effector mechanisms of neutrophilic granulocytes, macrophages and plasma cells are involved. Simultaneously, skin lesions contain anti-inflammatory mediators (e.g. interleukin-10) and show limited activity of Th22 and regulatory T cells. The inflammatory vicious circle finally results in pain, purulence, tissue destruction and scarring. Chronic inflammation in patients with HS is also frequently detected in organs other than the skin, as indicated by their comorbidities. All these aspects represent a challenge for the development of therapeutic approaches, which are urgently needed for this debilitating disease. This scholarly review focuses on the causes and pathogenetic mechanisms of HS and the potential therapeutic value of this knowledge.

Association of CCL2 with systemic inflammation in Schnitzler syndrome

BACKGROUND

Schnitzler syndrome (SchS) is a rare autoinflammatory disease characterized by urticarial exanthema, bone and joint alterations, fever and monoclonal gammopathy, which manifest mostly in the second half of life. It involves overactivation of the interleukin (IL)-1 system, but the exact pathophysiological pathways remain largely unknown.

OBJECTIVES

To identify and characterize the pathogenetic players in SchS.

METHODS

Blood parameters were quantified in patients with SchS compared with healthy controls and patients with psoriasis and hidradenitis suppurativa using enzyme-linked immunosorbent assay (ELISA). CCL2 expression in cultured primary cells was analysed by quantitative reverse-transcriptase polymerase chain reaction and ELISA.

RESULTS

CCL2, a chemoattractant for monocytic and further mononuclear immune cells, was found to be significantly elevated in patients with SchS. CCL2 levels showed a positive association with global disease activity, especially with bone pain, but not disease duration, gammopathy, neutrophilia or skin disease. In vitro stimulation assays demonstrated a strong CCL2 production capacity of mononuclear immune cells and fibroblasts, but not epithelial or endothelial cells. Among a range of inflammatory mediators, only IL-1β (immune cells, fibroblasts) and tumour necrosis factor (TNF)-α (fibroblasts) were important CCL2 inducers. TNF-α, but not IL-17, strengthened the CCL2-inducing effect of IL-1β in fibroblasts. Accordingly, CCL2 levels positively correlated with both TNF-α and IL-1β serum levels in patients with SchS. Therapeutic IL-1β blockade decreased CCL2 blood levels in these patients as early as 1 week after the initiation of treatment.

CONCLUSIONS

CCL2 may be an important component of the pathogenetic cascade leading to bone alterations, and a suitable marker of disease activity in patients with SchS.

[Acne inversa/hidradenitis suppurativa: An update]

Acne inversa (AI)/hidradenitis suppurativa is a chronic, recurrent, immune-mediated dermatosis characterized by deep inflammatory nodules, abscesses, fistulas, and undermined scars in skin areas bearing apocrine glands. In addition to the cutaneous manifestation, numerous AI patients show metabolic changes, spondyloarthritis, and depression. AI leads to a strong reduction in the quality of life and an impairment of the sexual life of affected individuals and often culminates in social withdrawal, stigmatization, unemployment, and suicidal thoughts. In this overview, we summarized the most important facts about AI and propose a simple algorithm for therapy.

Lipocalin-2 is expressed by activated granulocytes and keratinocytes in affected skin and reflects disease activity in acne inversa/hidradenitis suppurativa

BACKGROUND

Acne inversa (AI)/hidradenitis suppurativa is a chronic inflammatory disease characterized by painful axillary, inguinal and perianal skin lesions with deep-seated nodules, abscesses and fistulae.

OBJECTIVES

This study aimed to identify and characterize the key players in AI pathogenesis.

METHODS

Epidemiological and anamnestic data for patients with AI were collected, and blood and skin samples were also taken. Healthy participants and patients with psoriasis served as controls. Assessment of samples and cultures of primary cells was performed by enzyme-linked immunosorbent assay, quantitative polymerase chain reaction on reverse transcribed mRNA, and immunohistochemistry.

RESULTS

Of 35 mediators quantified in the blood of patients with AI, lipocalin-2 (LCN2) appeared as one of the most significantly upregulated parameters compared with healthy participants [85·8 ± 12·2 (n = 18) vs. 41·8 ± 4·2 (n = 15); P < 0·001]. Strongly elevated LCN2 expression was present in AI lesions, with granulocytes and keratinocytes being sources of this expression. In vitro, these cells upregulated LCN2 production in response to tumour necrosis factor (TNF)-α, and a positive relationship between systemic TNF-α and LCN2 levels (r_s = 0·55, P = 0·011; n = 20) was evident for AI. LCN2 blood levels correlated with AI disease severity (r_s = 0·65, P < 0·001; n = 29), but not with disease duration, age, sex, body mass index or smoking habit. Detailed analyses revealed a link with the number of skin regions containing nodules and fistulae, but not scars.

CONCLUSIONS

LCN2 might serve as a blood biomarker for the objective assessment of inflammatory activity in AI. We suggest a self-amplification loop comprising TNF-α, neutrophilic granulocytes and LCN2, which contributes to the recurrent skin neutrophil infiltration in AI, clinically evident as pus.

Long-term interleukin-10 presence induces the development of a novel, monocyte-derived cell type

Interleukin (IL)-10 is one of the most crucial immunoregulatory cytokines. Its short-term effects have been analysed extensively, but little is known about its long-term effects. This is of considerable importance, as high systemic IL-10 levels are present for long periods in patients with persistent viral infections, certain cancers and in critical care patients. Our study investigated the effects of the long-term presence of IL-10 on human peripheral blood monocytes. In vitro, IL-10 treatment of these cells for 7 days induced the development of a novel cell type characterized by unique phenotypical and functional characteristics. These cells showed high HLA-DR expression and low expression of CD86 and other co-stimulatory molecules on their surface. The mRNA levels of both HLA-DR and CD86 were high, but no intracellular accumulation of CD86 protein was observed. With respect to its function, these cells showed strongly diminished tumour necrosis factor-alpha production following lipopolysaccharide stimulation, strongly diminished allogenic CD4(+) T cell stimulatory capacity, and even induced a hyporesponsive state in CD4(+) T cells. The phenotype remained stable despite the removal of IL-10. In vivo, we found monocytic cells from patients exhibiting this phenotype after long-term IL-10 exposure. These results complement our knowledge further about the biological effects of IL-10 and may provide an explanation for the sustained immunodeficiency in cases of the persistent presence of systemic IL-10.

The expression of legumain, an asparaginyl endopeptidase that controls antigen processing, is reduced in endotoxin-tolerant monocytes

The exposition of monocytes to lipopolysaccharide (LPS) primarily causes a massive inflammatory response that is then followed by a hyporesponsive state of these cells. This latter state is called endotoxin tolerance and is characterized by (i) the attenuated production of proinflammatory mediators after repeated LPS treatment, and (ii) the diminished antigen presentation and T-cell stimulation capacity. The data presented here indicate that LPS priming causes a specific decrease in the expression of legumain (the asparaginyl endopeptidase responsible for the key step in antigen processing) in monocytes. In these cells, the fraction of major histocompatibility complex (MHC) class II loaded with CLIP was increased. In contrast to monocytes, LPS priming provoked an increase of legumain expression in B cells. Reduced monocytic expression of legumain was also found in critically ill patients supporting the suitability of endotoxin tolerance as an experimental model of clinical postinflammatory immunodeficiency.

Is there an interaction between interleukin-10 and interleukin-22?

Interleukin(IL)-10 and IL-22 are structurally related cytokines. Their heterodimeric receptors consist of the cytokine-specific chains IL-10R1 and IL-22R1, respectively, and the common chain IL-10R2. This study focused on the question of whether IL-10 modulates IL-22 effects and vice versa. This question is important because IL-10 and IL-22 exert anti- and proinflammatory effects, respectively, and, as we show here, are simultaneously present in both systemic and local inflammation. The revealed lacking concomitance of IL-10R1 and IL-22R1 on identical cells excluded any possible interaction between IL-10 and IL-22 apart from the competition for IL-10R2. To study this competition, monocytes and hepatocytes were chosen. The dependence of the cytokine action on IL-10R2 was verified. Interestingly, no influence of IL-22 on IL-10 effects was observed. The same was true when IL-22 was used in complex with IL-22-binding protein. Similarly, no influence of IL-10 was found on IL-22 action. This missing competition seemed to be due to a lack of binding between IL-10R2 and the native cytokines in the absence of their corresponding R1 chain. However, IL-10R2 interacted with defined IL-10- and IL-22-derived peptides supporting the hypothesis that cytokine binding to its corresponding R1 chain creates a binding site on this cytokine for IL-10R2.

Cloning of murine IL-22 receptor alpha 2 and comparison with its human counterpart

We have identified the mouse and rat homologs of human interleukin-22 receptor alpha 2 (IL-22R alpha 2) and compared the localization, structure, and expression of the encoding murine and human genes. The mouse IL-22R alpha 2-encoding gene is located on chromosome 10A3 between, like in human, the genes for interferon-gamma R1 and IL-20R1. It spans a region of approximately 10 kb therefore being three times shorter than the human gene. Although the overall gene structure in both species is similar, the mouse gene lacks a counterpart to the third coding exon of the human gene known to be alternatively spliced. Like in human, mouse and rat IL-22R alpha 2 exist only as soluble receptors as deduced from the lack of transmembrane and intracellular domains encoding sequences. Quantitative expression analyses showed, analogically to the human system, a limited tissue distribution of mouse IL-22R alpha 2 mRNA. Differential modulation of IL-22R alpha 2 mRNA expression was observed upon systemic inflammation in mice in spleen, thymus, and lymph node.

A novel, soluble homologue of the human IL-10 receptor with preferential expression in placenta

The cytokine receptor family type 2 (CRF2) comprises receptors for important immunomediators like interferons and interleukin-10 (IL-10). We identified a novel member of this family which represents the first exclusively soluble receptor in this group and was therefore designated as CRF2-soluble 1 (CRF2-s1). The CRF2-s1 gene covers about 28 kb and is located on chromosome 6 in close proximity to the CRF2 members interferon (IFN)-gamma receptor 1 and IL-20 receptor 1. It comprises seven exons and generates two different mRNA splice variants, CRF2-s1-long and CRF2-s1-short. CRF2-s1-long and CRF2-s1-short encode proteins of 263 and 231 amino acids, respectively. A comparison of predicted protein structures led to the postulation that each receptor variants binds a different ligand. Quantitative analysis of human mRNA expression revealed a very restricted pattern for both splice forms. CRF2-s1 turned out to be the first member of this receptor family which was expressed neither in resting nor in stimulated leucocyte populations. CRF2-s1-long was only expressed in placenta, whereas CRF2-s1-short was additionally expressed in human mammary gland and, at a lower level, in skin, spleen, thymus and stomach. The preferential expression of CRF2-s1 in placenta suggests a role for this receptor in establishing and maintaining successful pregnancy.

Impaired antigen presentation by human monocytes during endotoxin tolerance

Endotoxin tolerance (ET) has been described as a temporary alteration in the lipopolysaccharide (LPS) response of monocytic cells after an initial LPS exposure with respect to the production of soluble immunomodulators. Apart from the LPS response, monocytic cells play an important role in initiation of the specific immune response as antigen-presenting cells. This study investigated the capacity of human blood monocytes to induce T-cell stimulation in ET. First, the expression of monocyte surface molecules, important for T-cell interaction, was analyzed by flow cytometry. In vitro priming of peripheral blood mononuclear cells with LPS clearly down-regulates major histocompatibility complex class II molecules and the costimulatory molecule CD86. Both changes were dependent on the endogenous interleukin (IL)-10 and less so on the transforming growth factor-beta. In contrast, other accessory molecules on monocytes were only marginally down-regulated (CD58), were not significantly changed during ET (CD40), or even remained up-regulated after initial LPS priming (CD54, CD80). Second, an impact of these phenotypic alterations on the accessory function of monocytes was observed. This was manifested as diminished T-cell proliferation and interferon (IFN)-gamma release in response to the presence of different recall antigens. Neutralizing IL-10 during LPS priming prevented the diminished T-cell IFN-gamma production but had little effect on T-cell proliferation. These data confirm that ET is an appropriate model of the monocyte functional state in immunoparalysis, which is frequently observed in patients after septic shock, trauma, or major surgery.

Comparison of monocyte functions after LPS- or IL-10-induced reorientation: importance in clinical immunoparalysis

Immunoparalysis is an acquired immunodeficiency which may occur in patients after major surgery, burns, polytrauma and sepsis. It is associated with a modified state of monocytes marked by their altered capacity to induce antigen-specific T cell stimulation and to release various cytokines. However, the pathogenesis of immunoparalysis may differ in various patient groups. It can develop in patients after systemic hyperinflammation induced by gastrointestinal translocation of endotoxin (lipopolysaccharide, LPS) or sepsis, as well as in patients without preceding systemic inflammation but primary anti-inflammation, for instance induced by sympathetic activation. To further elucidate the syndrome, we compared endotoxin tolerance as a model of immunoparalysis after systemic hyperinflammation versus interleukin-10 (IL-10) treatment as a model of primarily anti-inflammation-induced immunoparalysis. In vitro priming of peripheral blood mononuclear cells with either LPS or IL-10 for 24 h led to a strongly or moderately diminished LPS-induced tumor necrosis factor-alpha (TNF-alpha) production, compared to unprimed controls, respectively. Furthermore, LPS-induced reduction of TNF-alpha production capacity persisted over the following days whereas IL-10-primed monocytes rapidly recovered. Similarly, in contrast to persistently diminished MHC class II expression in LPS-treated monocytes, IL-10 only transiently downregulated these molecules. Consequently, in contrast to IL-10-primed monocytes, LPS-primed monocytes were greatly impaired in their capacity to induce antigen-specific T cell proliferation and IFN-gamma production. These data indicate that LPS priming provokes a more profound modulation of monocyte function than IL-10 priming, raising the question of possible variations in the clinical course of immunoparalysis, dependent on its pathogenesis.