The effects of cholecalciferol and afamelanotide on vitamin D levels in erythropoietic protoporphyria; a multicentre cohort study.

BACKGROUND: Erythropoietic protoporphyria (EPP) patients experience lifelong painful photosensitivity resulting in a lack of sunlight exposure. Previous studies have shown that 47-63% of EPP patients suffer from vitamin D deficiency and a high prevalence of osteoporosis. As of 2016 an effective treatment for EPP is available: the alpha-MSH analogue afamelanotide. So far studies on vitamin D levels in EPP have only investigated patients who were not treated with afamelanotide. OBJECTIVES: To investigate the effects of afamelanotide treatment on vitamin D levels in EPP. METHODS: A multi-centre observational cohort study, in adult patients with EPP from the Erasmus Medical Centre, the Netherlands and the University Hospital Düsseldorf, Germany. Routinely-collected vitamin D levels between 2005 and 2021 were used for analysis. Patient exposure to cholecalciferol or afamelanotide was categorized into four treatment groups; untreated, cholecalciferol, afamelanotide, and combined treatment. A linear mixed model for longitudinal data was applied to measure the effect of the treatment groups, compared to the untreated, on vitamin D levels. RESULTS: A total of 230 patients and 1774 vitamin D measurements were included. Prevalence of vitamin D deficiency remained high despite afamelanotide treatment: <50 nmol/l in 71.8% of patients, and severe deficiency <30 nmol/l in 48.1%. Afamelanotide treatment alone did not lead to a significant average increase in vitamin D levels (ß:0.5, 95% Confidence Interval [CI]: -3.2 - 4.2). In contrast, cholecalciferol and combined therapy with afamelanotide, led to a significant increase in vitamin D levels (ß:11.6, CI: 7.2-15.9 and ß:15.2, CI: 12.3-18.1). CONCLUSION: Cholecalciferol remains essential for treatment of vitamin D deficiency in EPP, irrespective of new treatment options like afamelanotide. Afamelanotide treatment did not affect vitamin D levels. We suggest that future guidelines include continuous monitoring of vitamin D and prescription of cholecalciferol in all patients with EPP, including those treated with afamelanotide.

Steroid-dependent polyarthritis induced by immune checkpoint inhibitor therapy successfully treated with bimekizumab.

Immune checkpoint inhibitors (ICIs) are an integral part of modern-day cancer therapy. Along with a greatly improved antitumor response come a number of immune-related adverse events (irAEs), musculoskeletal irAEs rank among the less frequent manifestations. The mechanisms behind these events are poorly understood, and so far clear guidelines for therapeutic management beyond treatment with glucocorticosteroids are lacking. We present the case of a 72-year-old patient who developed a severe ICI-induced polyarthritis that could not be controlled by glucocorticosteroids. We initiated an immunomodulating therapy with the IL-17A/F/AF-inhibitor bimekizumab, which lead to a full clinical and sonographic remission.

In advanced stages, melanoma requires systemic therapy. Immune checkpoint inhibitors (ICIs) allow the body's own defense system to fight the cancer. They are an important part of this therapy. As a downside, they can cause immune-related side effects such as pain and inflammation in the joints. These are often chronic and have a great effect on the patient's quality of life. We therefore need long-term treatments that do not interfere with the intended antitumor response and allow the patients to live a nearly normal life. Corticosteroids often offer short-term relief. Patients whose symptoms cannot be steadily controlled by corticosteroids alone often need further medication. These substances aim to change the activity of the immune system. We present the case of a 72-year-old patient with a melanoma that had spread to other parts of the body. He suffered from great pain caused by inflammation of many of his joints. We could not control his symptoms using corticosteroids, so we decided to use the IL-17 blocker bimekizumab. This treatment is approved for psoriasis associated joint inflammation, inflammations of the spinal joints and psoriasis. This led to a rapid relief of joint pain and stiffness and allowed us to continue the melanoma therapy. The patient further continued to show a good antitumor response. As of this writing, the scans show no signs of cancer.

Cross-Comparison of Inflammatory Skin Disease Transcriptomics Identifies PTEN as a Pathogenic Disease Classifier in Cutaneous Lupus Erythematosus.

Tissue transcriptomics is used to uncover molecular dysregulations underlying diseases. However, the majority of transcriptomics studies focus on single diseases with limited relevance for understanding the molecular relationship between diseases or for identifying disease-specific markers. In this study, we used a normalization approach to compare gene expression across nine inflammatory skin diseases. The normalized datasets were found to retain differential expression signals that allowed unsupervised disease clustering and identification of disease-specific gene signatures. Using the NS-Forest algorithm, we identified a minimal set of biomarkers and validated their use as diagnostic disease classifier. Among them, PTEN was identified as being a specific marker for cutaneous lupus erythematosus and found to be strongly expressed by lesional keratinocytes in association with pathogenic type I IFNs. In fact, PTEN facilitated the expression of IFN-ß and IFN-κ in keratinocytes by promoting activation and nuclear translocation of IRF3. Thus, cross-comparison of tissue transcriptomics is a valid strategy to establish a molecular disease classification and to identify pathogenic disease biomarkers.

Long noncoding RNA plasmacytoma variant translocation 1 is overexpressed in cutaneous squamous cell carcinoma and exon 2 is critical for its oncogenicity.

BACKGROUND: Cutaneous squamous cell carcinoma (cSCC) is one of the most common and fastest increasing forms of cancer worldwide with metastatic potential. Long noncoding RNAs (lncRNAs) are a group of RNA molecules with essential regulatory functions in both physiological and pathological processes. OBJECTIVES: To investigate the function and mode of action of lncRNA plasmacytoma variant translocation 1 (PVT1) in cSCC. METHODS: Quantitative reverse transcriptase polymerase chain reaction and single-molecule in situ hybridization were used to quantify the expression level of PVT1 in normal skin, premalignant skin lesions, actinic keratosis (AK) and primary and metastatic cSCCs. The function of PVT1 in cSCC was investigated both in vivo (tumour xenografts) and in vitro (competitive cell growth assay, 5-ethynyl-2'-deoxyuridine incorporation assay, colony formation assay and tumour spheroid formation assay) upon CRISPR-Cas9-mediated knockout of the entire PVT1 locus, the knockout of exon 2 of PVT1, and locked nucleic acid (LNA) gapmer-mediated PVT1 knockdown. RNA sequencing analysis was conducted to identify genes and processes regulated by PVT1. RESULTS: We identified PVT1 as a lncRNA upregulated in cSCC in situ and cSCC, associated with the malignant phenotype of cSCC. We showed that the expression of PVT1 in cSCC was regulated by MYC. Both CRISPR-Cas9 deletion of the entire PVT1 locus and LNA gapmer-mediated knockdown of PVT1 transcript impaired the malignant behaviour of cSCC cells, suggesting that PVT1 is an oncogenic transcript in cSCC. Furthermore, knockout of PVT1 exon 2 inhibited cSCC tumour growth both in vivo and in vitro, demonstrating that exon 2 is a critical element for the oncogenic role of PVT1. Mechanistically, we showed that PVT1 was localized in the cell nucleus and its deletion resulted in cellular senescence, increased cyclin-dependent kinase inhibitor 1 (p21/CDKN1A) expression and cell cycle arrest. CONCLUSIONS: Our study revealed a previously unrecognized role for exon 2 of PVT1 in its oncogenic role and that PVT1 suppresses cellular senescence in cSCC. PVT1 may be a potential biomarker and therapeutic target in cSCC.

Novel methodologies for host-microbe interactions and microbiome-targeted therapeutics in 3D organotypic skin models.

BACKGROUND: Following descriptive studies on skin microbiota in health and disease, mechanistic studies on the interplay between skin and microbes are on the rise, for which experimental models are in great demand. Here, we present a novel methodology for microbial colonization of organotypic skin and analysis thereof. RESULTS: An inoculation device ensured a standardized application area on the stratum corneum and a homogenous distribution of bacteria, while preventing infection of the basolateral culture medium even during prolonged culture periods for up to 2 weeks at a specific culture temperature and humidity. Hereby, host-microbe interactions and antibiotic interventions could be studied, revealing diverse host responses to various skin-related bacteria and pathogens. CONCLUSIONS: Our methodology is easily transferable to a wide variety of organotypic skin or mucosal models and different microbes at every cell culture facility at low costs. We envision that this study will kick-start skin microbiome studies using human organotypic skin cultures, providing a powerful alternative to experimental animal models in pre-clinical research. Video Abstract.

Unleashing T cell anti-tumor immunity: new potential for 5-Nonloxytryptamine as an agent mediating MHC-I upregulation in tumors.

BACKGROUND: New therapies are urgently needed in melanoma, particularly in late-stage patients not responsive to immunotherapies and kinase inhibitors. To uncover novel potentiators of T cell anti-tumor immunity, we carried out an ex vivo pharmacological screen and identified 5-Nonyloxytryptamine (5-NL), a serotonin agonist, as increasing the ability of T cells to target tumor cells. METHODS: The pharmacological screen utilized lymphocytic choriomeningitis virus (LCMV)-primed splenic T cells and melanoma B16.F10 cells expressing the LCMV gp33 CTL epitope. In vivo tumor growth in C57BL/6 J and NSG mice, in vivo antibody depletion, flow cytometry, immunoblot, CRISPR/Cas9 knockout, histological and RNA-Seq analyses were used to decipher 5-NL's immunomodulatory effects in vitro and in vivo. RESULTS: 5-NL delayed tumor growth in vivo and the phenotype was dependent on the hosts' immune system, specifically CD8+ T cells. 5-NL's pro-immune effects were not directly consequential to T cells. Rather, 5-NL upregulated antigen presenting machinery in melanoma and other tumor cells in vitro and in vivo without increasing PD-L1 expression. Mechanistic studies indicated that 5-NL's induced MHC-I expression was inhibited by pharmacologically preventing cAMP Response Element-Binding Protein (CREB) phosphorylation. Importantly, 5-NL combined with anti-PD1 therapy showed significant improvement when compared to single anti-PD-1 treatment. CONCLUSIONS: This study demonstrates novel therapeutic opportunities for augmenting immune responses in poorly immunogenic tumors.

Itch, sleep loss, depressive symptoms, fatigue, and productivity loss in patients with moderate-to-severe atopic dermatitis: Analyses of TREATgermany registry data.

BACKGROUND: TREATgermany is a multicenter registry including patients with moderate-to-severe atopic dermatitis (AD) from currently 74 study centers (university clinics, hospitals and practices) in Germany. As of August 31, 2021, 1,230 adult patients were enrolled. METHODS: In TREATgermany, patients and physicians fill in questionnaires pertaining to symptoms, disease severity, quality of life, depressiveness, and fatigue. In particular, limitations in work performance are assessed using the Work Limitations Questionnaire (WLQ). To assess associations between occupational performance/work limitations and symptoms, correlations and regression models were calculated. RESULTS: The examined sample of 228 employed patients reported an average of 6% at-work productivity loss within the past two weeks prior to enrolment in the registry. The WLQ productivity loss score was moderately associated with itch (r = 0.32) and sleep loss (r = 0.39) and strongly associated with depressive symptoms (r = 0.68) and fatigue (r = 0.60). CONCLUSIONS: The analyses of the registry data show that moderate-to-severe atopic dermatitis has a negative impact on the work productivity of the patients. The analyses further point out the relevant associations between work productivity, depressive symptoms, and fatigue highlighting the disease burden caused by the psychological components of AD.

MicroRNA-23b Plays a Tumor-Suppressive Role in Cutaneous Squamous Cell Carcinoma and Targets Ras-Related Protein RRAS2.

Cutaneous squamous cell carcinoma (cSCC) is one of the most common types of cancer with metastatic potential. MicroRNAs regulate gene expression at the post-transcriptional level. In this study, we report that miR-23b is downregulated in cSCCs and in actinic keratosis and that its expression is regulated by the MAPK signaling pathway. We show that miR-23b suppresses the expression of a gene network associated with key oncogenic pathways and that the miR-23b-gene signature is enriched in human cSCCs. miR-23b decreased the expression of FGF2 both at mRNA and protein levels and impaired the angiogenesis-inducing ability of cSCC cells. miR23b overexpression suppressed the capacity of cSCC cells to form colonies and spheroids, whereas the CRISPR/Cas9-mediated deletion of MIR23B resulted in increased colony and tumor sphere formation in vitro. In accordance with this, miR-23b-overexpressing cSCC cells formed significantly smaller tumors upon injection into immunocompromised mice with decreased cell proliferation and angiogenesis. Mechanistically, we verify RRAS2 as a direct target of miR-23b in cSCC. We show that RRAS2 is overexpressed in cSCC and that interference with its expression impairs angiogenesis and colony and tumorsphere formation. Taken together, our results suggest that miR-23b acts in a tumor-suppressive manner in cSCC, and its expression is decreased during squamous carcinogenesis.

The Endogenous Dual Retinoid Receptor Agonist Alitretinoin Exhibits Immunoregulatory Functions on Antigen-Presenting Cells.

Retinoids are a frequently used class of drugs in the treatment of inflammatory as well as malignant skin diseases. Retinoids have differential affinity for the retinoic acid receptor (RAR) and/or the retinoid X receptor (RXR). The endogenous dual RAR and RXR agonist alitretinoin (9-cis retinoic acid) demonstrated remarkable efficacy in the treatment of chronic hand eczema (CHE) patients; however, detailed information on the mechanisms of action remains elusive. Here, we used CHE as a model disease to unravel immunomodulatory pathways following retinoid receptor signaling. Transcriptome analyses of skin specimens from alitretinoin-responder CHE patients identified 231 significantly regulated genes. Bioinformatic analyses indicated keratinocytes as well as antigen presenting cells as cellular targets of alitretinoin. In keratinocytes, alitretinoin interfered with inflammation-associated barrier gene dysregulation as well as antimicrobial peptide induction while markedly inducing hyaluronan synthases without affecting hyaluronidase expression. In monocyte-derived dendritic cells, alitretinoin induced distinct morphological and phenotypic characteristics with low co-stimulatory molecule expression (CD80 and CD86), the increased secretion of IL-10 and the upregulation of the ecto-5'-nucleotidase CD73 mimicking immunomodulatory or tolerogenic dendritic cells. Indeed, alitretinoin-treated dendritic cells demonstrated a significantly reduced capacity to activate T cells in mixed leukocyte reactions. In a direct comparison, alitretinoin-mediated effects were significantly stronger than those observed for the RAR agonist acitretin. Moreover, longitudinal monitoring of alitretinoin-responder CHE patients could confirm in vitro findings. Taken together, we demonstrate that the dual RAR and RXR agonist alitretinoin targets epidermal dysregulation and demonstrates strong immunomodulatory effects on antigen presenting cell functions.

Basal Proliferation and Acantholysis May Represent Histological High-Risk Factors for Progression into Invasive Squamous Cell Carcinoma: A Comparison Study in Solid Organ Transplant Recipients and Matched Immunocompetent Patients.

Histological risk factors of AKs cannot be directly determined. Recent studies indicate that AKs restricted to the lower third of the epidermis (AK I), with marked basal proliferation (PRO III) and acantholysis, are associated with an increased risk of progression to invasive squamous cell carcinoma (iSCC). To confirm the aforementioned histological risk factors, this study compared AKs from solid organ transplant recipients (sOTRs), known to carry an up to 250-fold higher risk for progression into iSCC, to a matched immunocompetent control group (ICG). In total, 111 AKs from 43 sOTRs showed more AKs (n = 54, 48.7%) graded as AK I compared to 35 AKs (31.5%) in the ICG (p = 0.009). In line with these findings, 89 AKs (80.2%) from sOTRs showed pronounced basal proliferation (PRO III) compared to 37 AKs (33.3%) in the ICG (p < 0.0001). Acantholysis was more frequent in sOTRs than the ICG (59.5% vs. 32.4%, p < 0.0001) and more frequently associated with advanced basal proliferation (p < 0.0001). In conclusion, this study showed that acantholytic AKs graded as AK I and PRO III are predominantly found in a population at high risk of iSCC. Thus, AKs with marked basal proliferation and acantholysis should be assumed to be histological high-risk factors for the progression into iSCC.

Time- and Dose-Dependent Effects of Hyaluronidase on the Degradation of Different Hyaluronan-Based Fillers In Vitro.

BACKGROUND: Hyaluronidase (HYAL) is regarded as the standard for the management of complications associated with hyaluronan (HA)-based fillers. Therefore, the understanding of interactions of HA fillers and HYAL is essential. METHODS: Nine different commercially available HA fillers (Belotero, Juvéderm, and Restylane) with varying degrees of cross-linking were used for the analysis. Fluorescently dyed HA fillers were individually incubated with varying doses of HYAL [bovine HYAL (Hylase "Dessau"; Riemser Pharma, Germany); 5, 10, and 20 U/mL] or sodium chloride and monitored by time-lapse microscopy. HA filler degradation was assessed as a decrease in fluorescence intensity of HA filler plus HYAL compared to HA filler plus control, quantified by computerized image analysis. RESULTS: HA fillers show significant differences in their reaction to HYAL. Levels of degradation of HA fillers are positively correlated with increasing concentrations of HYAL. At the highest concentration of HYAL (20 U/mL), all fillers except one (Belotero Volume) reached a significant level of degradation at 5 to 9 hours. CONCLUSIONS: In this study, the authors show that most HA fillers can be dissolved by HYAL in a dose- and time-dependent manner. Of note, the fillers' technology and degree of cross-linking seem to exert stronger effects on the degradability by HYAL as compared to the concentration of HA. CLINICAL RELEVANCE STATEMENT: The authors' in vitro analyses support clinical recommendations stating that in the case of a vascular filler incident, HYAL should be applied early and at significant doses ("Time is skin!"). CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.

Percutaneous fractionated radiotherapy of the groin to eliminate lymphatic fistulas after vascular surgery.

BACKGROUND: Vascular surgery of the inguinal area can be complicated by persistent lymphatic fistulas. Rapid and effective treatment is essential to prevent infection, sepsis, bleeding, and possible leg amputation. Current data on irradiation of lymphatic fistulas lack recommendation on the appropriate individual and total dose, the time of irradiation, and the target volume. Presumably, a dose of 0.3-0.5 to 1-12 Gy should be sufficient for the purpose. Currently, radiotherapy is a "can" recommendation, with a level 4 low evidence and a grade C recommendation, according to the DEGRO S2 guidelines. As part of a pilot study, we analyzed the impact and limitations of low-dose radiation therapy in the treatment of inguinal lymphatic fistulas. PATIENTS AND METHODS: As a part of an internal quality control project, patients with lymphatic fistulas irradiated in the groin area after vascular surgery for arterial occlusive disease (AOD) III-IV, repair of pseudo aneurysm or lymph node dissection due to melanoma were selected, and an exploratory analysis on retrospectively collected data performed. RESULTS: Twelve patients (10 males and 2 females) aged 62.83 ± 12.14 years underwent open vascular reconstruction for stage II (n = 2), III (n = 1), and IV (n = 7) arterial occlusive disease (AOD), lymph node dissection for melanoma (n = 1) or repair of a pseudoaneurysm (n = 1). Surgical vascular access was obtained through the groin and was associated with a persistent lymphatic fistula, secreting more than 50 ml/day. Patients were irradiated five times a week up to a maximum of 10 fractions for the duration of the radiation period. Fraction of 0.4 Gy was applied in the first 7 cases, while 5 patients were treated with a de-escalating dose of 0.3 Gy. There was a resolution of the lymphatic fistula in every patient without higher grade complications. CONCLUSION: Low-dose irradiation of the groin is a treatment option for persistent lymphatic fistula after inguinal vascular surgery.

Type I IFNs link skin-associated dysbiotic commensal bacteria to pathogenic inflammation and angiogenesis in rosacea.

Rosacea is a common chronic inflammatory skin disease with a fluctuating course of excessive inflammation and apparent neovascularization. Microbial dysbiosis with a high density of Bacillus oleronius and increased activity of kallikrein 5, which cleaves cathelicidin antimicrobial peptide, are key pathogenic triggers in rosacea. However, how these events are linked to the disease remains unknown. Here, we show that type I IFNs produced by plasmacytoid DCs represent the pivotal link between dysbiosis, the aberrant immune response, and neovascularization. Compared with other commensal bacteria, B. oleronius is highly susceptible and preferentially killed by cathelicidin antimicrobial peptides, leading to enhanced generation of complexes with bacterial DNA. These bacterial DNA complexes but not DNA complexes derived from host cells are required for cathelicidin-induced activation of plasmacytoid DCs and type I IFN production. Moreover, kallikrein 5 cleaves cathelicidin into peptides with heightened DNA binding and type I IFN-inducing capacities. In turn, excessive type I IFN expression drives neoangiogenesis via IL-22 induction and upregulation of the IL-22 receptor on endothelial cells. These findings unravel a potentially novel pathomechanism that directly links hallmarks of rosacea to the killing of dysbiotic commensal bacteria with induction of a pathogenic type I IFN-driven and IL-22-mediated angiogenesis.

Itching in Atopic Dermatitis: Patient- and Physician-reported Outcomes in the German Atopic Dermatitis Registry TREATgermany.

TREATgermany is an investigator-initiated prospective disease registry. It investigates physician- and patient-reported disease severity (Eczema Area and Severity Index (EASI), objective Scoring Atopic Dermatitis (oSCORAD), Investigator Global Assessment, Patient-Oriented Eczema Measure (POEM), Patient Global Assessment (PGA)), patient-reported symptoms (itch, sleep loss, depressive symptoms), therapy courses and dermatological quality of life (DLQI) in moderate-to-severe atopic dermatitis with SCORAD > 20. 1,134 atopic dermatitis patients (mean age 41.0 ± 14.7 years, 42.5% females) were enrolled by 40 German recruiting sites (dermatological clinics and practices) between June 2016 and April 2021. The current analysis focuses on itch scores obtained with a numerical rating scale (NRS)) documented for the previous 3 days prior to baseline visit. The results show that 97.2% (1,090 of 1,121) patients experienced itch. Itch severity correlated moderately with severity of atopic dermatitis oSCORAD (rho = 0.44 (0.39-0.48)) and EASI score (rho = 0.41 (0.36-0.46)). A strong correlation was found with self-reported disease severity as PGA (rho = 0.68 (0.65-0.71)), POEM sum score (rho = 0.66 (0.63-0.69)) and dermatological quality of life impairment DLQI (rho = 0.61 (0.57-0.65)). Itch as a subjective complaint is more closely correlated with patient-reported outcomes than with objective assessments by the physician.

Characterization of the skin microbiota in bullous pemphigoid patients and controls reveals novel microbial indicators of disease.

INTRODUCTION: Bullous pemphigoid (BP) is the most common autoimmune blistering disease. It predominately afflicts the elderly and is significantly associated with increased mortality. The observation of age-dependent changes in the skin microbiota as well as its involvement in other inflammatory skin disorders suggests that skin microbiota may play a role in the emergence of BP blistering. We hypothesize that changes in microbial diversity associated with BP might occur before the emergence of disease lesions, and thus could represent an early indicator of blistering risk. OBJECTIVES: The present study aims to investigate potential relationships between skin microbiota and BP and elaborate on important changes in microbial diversity associated with blistering in BP. METHODS: The study consisted of an extensive sampling effort of the skin microbiota in patients with BP and age- and sex-matched controls to analyze whether intra-individual, body site, and/or geographical variation correlate with changes in skin microbial composition in BP and/or blistering status. RESULTS: We find significant differences in the skin microbiota of patients with BP compared to that of controls, and moreover that disease status rather than skin biogeography (body site) governs skin microbiota composition in patients with BP. Our data reveal a discernible transition between normal skin and the skin surrounding BP lesions, which is characterized by a loss of protective microbiota and an increase in sequences matching Staphylococcus aureus, a known inflammation-promoting species. Notably, Staphylococcus aureus is ubiquitously associated with BP disease status, regardless of the presence of blisters. CONCLUSION: The present study suggests Staphylococcus aureus may be a key taxon associated with BP disease status. Importantly, we however find contrasting patterns in the relative abundances of Staphylococcus hominis and Staphylococcus aureus reliably discriminate between patients with BP and matched controls. This may serve as valuable information for assessing blistering risk and treatment outcomes in a clinical setting.

Structure and Dynamics of Human Chemokine CCL16-Implications for Biological Activity.

Human C-C motif ligand 16 (CCL16) is a chemokine that is distinguished by a large cleavable C-terminal extension of unknown significance. Conflicting data have been reported concerning its tissue distribution and modulation of expression, rendering the biological function of CCL16 enigmatic. Here, we report an integrated approach to the characterisation of this chemokine, including a re-assessment of its expression characteristics as well as a biophysical investigation with respect to its structure and dynamics. Our data indicate that CCL16 is chiefly synthesised by hepatocytes, without an appreciable response to mediators of inflammation, and circulates in the blood as a full-length protein. While the crystal structure of CCL16 confirms the presence of a canonical chemokine domain, molecular dynamics simulations support the view that the C-terminal extension impairs the accessibility of the glycosaminoglycan binding sites and may thus serve as an intrinsic modulator of biological activity.