Non-alcoholic fatty liver disease and psoriasis - is there a shared proinflammatory network?

Psoriasis is an immune-mediated systemic inflammatory disease that is not limited to the skin but may be associated with arthritis, cardiovascular diseases, metabolic syndrome including diabetes and obesity and, as identified more recently, non-alcoholic fatty liver disease (NAFLD) that occurs in approximately 50 % of all patients with psoriasis. NAFLD is characterized by accumulation of fat in hepatocytes in the absence of excessive alcohol consumption. Over the last two decades, NAFLD has developed to the most common chronic liver disease with an estimated prevalence of 25 % in the Western population. NAFLD ranges from non-inflammatory or bland hepatic steatosis to inflammation of hepatic tissue (non-alcoholic steatohepatitis, NASH) and consecutive liver fibrosis. It is controversial whether the underlying systemic inflammation of psoriasis is contributing to development of NAFLD or if comorbid diseases such as obesity enhance NAFLD development. Recent findings indicate that cytokine-mediated inflammation through TNFα, interleukin (IL)-6 and IL-17 might be the common link between psoriasis and NAFLD. Considering the shared inflammatory pathways, IL-17 pharmacological blockade, which is already well-established for psoriasis, may be a promising strategy to treat both psoriasis and NAFLD. Therefore, early detection of NAFLD and a better understanding of its pathophysiology in the context of the systemic inflammation in psoriasis is important with regard to individualized treatment approaches.

Partial-volume correction in dynamic PET-CT: effect on tumor kinetic parameter estimation and validation of simplified metrics

Background

Partial-volume effects generally result in an underestimation of tumor tracer uptake on PET-CT for small lesions, necessitating partial-volume correction (PVC) for accurate quantification. However, investigation of PVC in dynamic oncological PET studies to date is scarce. The aim of this study was to investigate PVC’s impact on tumor kinetic parameter estimation from dynamic PET-CT acquisitions and subsequent validation of simplified semi-quantitative metrics. Ten patients with EGFR-mutated non-small cell lung cancer underwent dynamic ¹⁸F-fluorothymidine PET-CT before, 7 days after, and 28 days after commencing treatment with a tyrosine kinase inhibitor. Parametric PVC was applied using iterative deconvolution without and with highly constrained backprojection (HYPR) denoising, respectively. Using an image-derived input function with venous parent plasma calibration, we estimated full kinetic parameters V_T, K₁, and k₃/k₄ (BP_ND) using a reversible two-tissue compartment model, and simplified metrics (SUV and tumor-to-blood ratio) at 50–60 min post-injection.

Results

PVC had a non-linear effect on measured activity concentrations per timeframe. PVC significantly changed each kinetic parameter, with a median increase in V_T of 11.8% (up to 25.1%) and 10.8% (up to 21.7%) without and with HYPR, respectively. Relative changes in kinetic parameter estimates vs. simplified metrics after applying PVC were poorly correlated (correlations 0.36–0.62; p < 0.01). PVC increased correlations between simplified metrics and V_T from 0.82 and 0.81 (p < 0.01) to 0.90 and 0.88 (p < 0.01) for SUV and TBR, respectively, albeit non-significantly. PVC also increased correlations between treatment-induced changes in simplified metrics vs. V_T at 7 (SUV) and 28 (SUV and TBR) days after treatment start non-significantly. Delineation on partial-volume corrected PET images resulted in a median decrease in metabolic tumor volume of 14.3% (IQR − 22.1 to − 7.5%), and increased the effect of PVC on kinetic parameter estimates.

Conclusion

PVC has a significant impact on tumor kinetic parameter estimation from dynamic PET-CT data, which differs from its effect on simplified metrics. However, it affected validation of these simplified metrics both as single measurements and as biomarkers of treatment response only to a small extent. Future dynamic PET studies should preferably incorporate PVC.

Trial registration

Dutch Trial Register, NTR3557.

Electronic supplementary material

The online version of this article (10.1186/s13550-019-0483-z) contains supplementary material, which is available to authorized users.

[Epidemiology, patient quality of life, and treatment costs of hidradenitis suppurativa/acne inversa]

Hidradenitis suppurativa/acne inversa (HS) is associated with numerous and relevant restrictions on the quality of life for those affected and their relatives. The exact prevalence of HS varies significantly across studies, but it is likely to be higher than suggested in previous publications. HS care is associated with high costs for the healthcare system and for those affected. The introduction of biologic therapy has led to additional costs, but also to considerable additional benefits in terms of care. In view of the complexity of diagnostics and therapy, there is a particular need for optimized care concepts in order to reduce the burden on those affected, their relatives and the healthcare system.

Stress signaling and STAT1 activation characterize the keratinocytic gene expression pattern in Hidradenitis suppurativa

BACKGROUND

The pathogenetic factors generating the innate immune signal necessary for T cell activation, initiation and chronification of Hidradenitis suppurativa (HS, also known as Acne inversa) are still poorly understood. Emerging evidence suggests that a defective keratinocyte function critically contributes to HS disease development and progression.

OBJECTIVES

To elucidate the role of keratinocytes in HS lesion formation, we compared the transcriptomes of lesional and perilesional epidermis isolated from HS patients by RNA sequencing (RNA Seq).

METHODS

Pairwise-matched lesional and perilesional HS skin samples of five different donors were obtained and epidermal keratinocytes freshly isolated and processed for RNA extraction and RNA seq. Lesionally regulated genes were analyzed by large scale promotor analysis and functional annotation clustering to identify epidermally overrepresented transcription factor binding sites and functionally related gene groups. Results were experimentally validated with independent epidermal isolates of patient-matched lesional and perilesional HS skin employing qRT-PCR, cell culture, immunoblot, and immunostaining.

RESULTS

We show that HS is characterized by a strong epidermal stress state evident by a significant overrepresentation of an AP-1-driven gene signature and a substantial activation of the stress-activated cJun N-terminal kinase (JNK) pathway in lesional epidermis. Additionally, our data reveal a strong induction of STAT1 activation in lesional HS epidermis that likely results from IFNγ production and triggered expression of key inflammatory genes coordinating innate immune activation and the adaptive T cell response in HS.

CONCLUSIONS

Our data implicate a key role of stress signaling and JAK/STAT1 activation in disease progression of HS and suggest interference with JAK/STAT1 signaling as a potentially promising therapeutic approach for HS.

Improved metal allergen reactivity of artificial skin models by integration of Toll-like receptor 4-positive cells

BACKGROUND

Reconstructed human epidermis (RhE) is widely used to replace animal models in order to assess the proinflammatory and allergenic effects of chemicals. Unfortunately, RhE lacks proinflammatory responsiveness for metal haptens, which are the most prevalent human contact allergens, raising concerns about its reliability for predicting skin allergens.

OBJECTIVES

To investigate whether this limitation of RhE might be attributable to a lack of functional expression of Toll-like receptor 4 (TLR4), which governs proinflammatory sensitivity to nickel and cobalt.

MATERIALS AND METHODS

RhE, dendritic cell (DC)-containing RhE and full-thickness skin equivalent (FTSE) were compared regarding their proinflammatory responsiveness to metal allergens.

RESULTS

The incorporation of dermal fibroblasts was sufficient to confer metal sensitivity to RhE. Unlike keratinocytes, normal human fibroblasts expressed high levels of TLR4 mRNA and induced interleukin-8 expression upon stimulation with nickel or cobalt. Consistently, dermal isolates from FTSE expressed considerable amounts of TLR4 mRNA, whereas RhE or epidermis isolated from FTSE, normal human epidermis or inflamed human epidermis failed to express TLR4. Similarly, co-culture with TLR4-positive DCs bestowed RhE with proinflammatory responsiveness to metals.

CONCLUSION

Our data suggest that FTSE or DC/RhE co-culture models can circumvent the shortcomings of RhE assays, and combine the benefits of complex and monoculture-based test systems in a single assay.

Validation of [18F]FLT as a perfusion-independent imaging biomarker of tumour response in EGFR-mutated NSCLC patients undergoing treatment with an EGFR tyrosine kinase inhibitor

Background

3′-Deoxy-3′-[¹⁸F]fluorothymidine ([¹⁸F]FLT) was proposed as an imaging biomarker for the assessment of in vivo cellular proliferation with positron emission tomography (PET). The current study aimed to validate [¹⁸F]FLT as a perfusion-independent PET tracer, by gaining insight in the intra-tumoural relationship between [¹⁸F]FLT uptake and perfusion in non-small cell lung cancer (NSCLC) patients undergoing treatment with a tyrosine kinase inhibitor (TKI).

Six patients with metastatic NSCLC, having an activating epidermal growth factor receptor (EGFR) mutation, were included in this study. Patients underwent [¹⁵O]H₂O and [¹⁸F]FLT PET/CT scans at three time points: before treatment and 7 and 28 days after treatment with a TKI (erlotinib or gefitinib). Parametric analyses were performed to generate quantitative 3D images of both perfusion measured with [¹⁵O]H₂O and proliferation measured with [¹⁸F]FLT volume of distribution (V_T). A multiparametric classification was performed by classifying voxels as low and high perfusion and/or low and high [¹⁸F]FLT V_T using a single global threshold for all scans and subjects. By combining these initial classifications, voxels were allocated to four categories (low perfusion-low V_T, low perfusion-high V_T, high perfusion-low V_T and high perfusion-high V_T).

Results

A total of 17 perfusion and 18 [¹⁸F]FLT PET/CT scans were evaluated. The average tumour values across all lesions were 0.53 ± 0.26 mL cm^− 3 min^− 1 and 4.25 ± 1.71 mL cm^− 3 for perfusion and [¹⁸F]FLT V_T, respectively. Multiparametric analysis suggested a shift in voxel distribution, particularly regarding the V_T: from an average of ≥ 77% voxels classified in the “high V_T category” to ≥ 85% voxels classified in the “low V_T category”. The shift was most prominent 7 days after treatment and remained relatively similar afterwards. Changes in perfusion and its spatial distribution were minimal.

Conclusion

The present study suggests that [¹⁸F]FLT might be a perfusion-independent PET tracer for measuring tumour response as parametric changes in [¹⁸F]FLT uptake occurred independent from changes in perfusion.

Trial registration

Nederlands Trial Register (NTR), NTR3557. Registered 2 August 2012

Electronic supplementary material

The online version of this article (10.1186/s13550-018-0376-6) contains supplementary material, which is available to authorized users.

Paraproteinaemia in Primary Cutaneous Marginal Zone Lymphoma

Primary cutaneous marginal zone lymphomas (PCMZL) frequently exhibit lymphoplasmacytoid/plasmacytic differentiation, implying the capacity to produce monoclonal immunoglobulins. As these paraproteins are secreted, and thus are measurable in blood and urine, they may correlate with disease burden and serve as tumour markers reflecting therapeutic response. This study retrospectively analysed the records of 23 patients with PCMZL. During treatment and follow-up, laboratory tests, including full blood count, lactate dehydrogenase, serum protein electrophoresis and turbidimetric analyses, were conducted. Thirty-nine percent of cases showed a suspicious serum protein electrophoresis in terms of paraproteinaemia. In 44% of cases the heavy and light chain restriction in tissue samples correlated with serological findings. Altogether, 89% of the PCMZL patients with paraproteinaemia eventually experienced a relapse, in contrast to 62% of the group without paraproteinaemia. This study analysed the incidence and clinical implications of paraproteinaemia in patients with PCMZL. A clear correlation was found between paraproteinaemia, tumour relapse and therapeutic intervention.

EBER in situ hybridization in subcutaneous aluminum granulomas/lymphoid hyperplasia: A diagnostic clue to differentiate injection-associated lymphoid hyperplasia from other forms of pseudolymphomas and cutaneous lymphomas

BACKGROUND

Subcutaneous vaccination or desensitization may induce persistent nodules at the injection sites. Without the knowledge of prior injection, histopathological work-up may be challenging.

OBJECTIVE

Aim of this study was to contribute to the histopathological work-up of unclear subcutaneous nodules, especially their differentiation from cutaneous lymphoma.

METHODS

We retrospectively reviewed clinical data and histopathological slides of four patients with subcutaneous nodules, which were suspected to suffer from cutaneous T- or B-cell lymphoma. Sections of these cases and 12 negative controls were stained with hematoxylin and eosin and a standardized immunohistochemical panel of B- and T-cell markers including EBER in situ hybridization as well as electron microscopy.

RESULTS

In all cases, large histiocytes with granular cytoplasm compatible with intracellular aluminum hydroxide were present. EBER in situ hybridization revealed positive staining of these granular histiocytes while staining was absent in negative controls.

LIMITATIONS

Post hoc completion of medical history revealed that vaccination or specific immunotherapy had been applied before at the biopsy site in only three out of four patients; one patient was lost to follow-up.

CONCLUSION

EBER in situ hybridization is an adjunctive tool to differentiate aluminum-induced granuloma/lymphoid hyperplasia from other forms of pseudolymphoma and cutaneous B- or T-cell lymphomas.

Expression of Connexin 43 in Granular Cell Tumors of the Skin, Tongue and Esophagus

BACKGROUND

Granular cell tumors (GCT) are rare neoplasms of Schwann cell origin occurring in the skin and in other organs. The etiopathogenesis of GCT is yet poorly understood. Connexin 43 (Cx43) is the most broadly expressed gap junction protein in humans, the tumoral role of which has been investigated in several types of tumors. Its role in GCT of the skin, oral cavity and gastrointestinal tract is as yet unknown.

METHODS

Herein, we present a study on the immunohistochemical expression of Cx43 in GCT of the skin (n = 15), tongue (n = 4) and esophagus (n = 3). Immunolabeling was scored positive (weak (+), moderate (++) or strong (+++)).

RESULTS

Cx43 was expressed by all cases of GCT of the skin, tongue and esophagus (22/22), showing moderate to strong staining. All tissue sections of GCT were characterized by a diffuse, cytoplasmic staining pattern of the tumor cells. None of those showed membranous or nuclear staining.

CONCLUSION

Our results suggest that Cx43 probably plays an important role in the development of this rare tumor entity.

Hidradenitis Suppurativa: Absence of Hyperhidrosis but Presence of a Proinflammatory Signature in Patients’ Sweat

The role of sweat glands in hidradenitis suppurativa has been largely neglected, despite the fact that its original designation, as “hidrosadénite phlegmoneuse”, implied an inflammatory malfunction of the apocrine sweat glands as the underlying pathogenic driver. The aim of this study was to evaluate the role of apocrine sweat glands with respect to the proinflammatory environment of hidradenitis suppurativa. Therefore, gravimetric assessment and multiplex cytokine assays from sweat obtained from patients with hidradenitis suppurativa along with immunofluorescence cytokine/chemokine analysis of lesional apocrine glands-bearing hidradenitis suppurativa skin were performed. Gravimetric assessment of 17 patients with hidradenitis suppurativa revealed that the condition is not associated with hyperhidrosis. However, patients seem to be more affected by subjective sweating. The current data identified a complex proinflammatory signature in hidradenitis suppurativa sweat characterized by a significant upregulation of monocyte chemoattractant protein-1, interleukin-8 (CXCL8), and interferon-γ. In agreement with this, a strong in situ expression of these mediators could be observed in apocrine glands of lesional hidradenitis suppurativa skin. These data shed new light on the proinflammatory capacity of apocrine sweat glands in hidradenitis suppurativa, which may lead to reconsideration of the role of sweat glands in hidradenitis suppurativa pathology.