POS0402 CLONALLY EXPANDED CD38hi CYTOTOXIC CD8 T CELLS DEFINE THE T CELL INFILTRATE IN CHECKPOINT INHIBITOR-ASSOCIATED ARTHRITIS

Background

Immune checkpoint inhibitor (ICI) therapies that promote T cell activation have improved outcomes for advanced malignancies yet can also elicit harmful autoimmune reactions. The T cell mechanisms mediating these iatrogenic autoimmune events remain unclear.

Objectives

To investigate the immunophenotype, transcriptomic feature and clonotypes of T cells from joints of patients affected by ICI-induced inflammatory arthritis (ICI-arthritis).

Methods

Detailed immunophenotyping was performed on mononuclear cells from synovial fluid (SF) using mass cytometry and flow cytometry to identify significantly altered populations in ICI-A compared to seropositive rhrumatoid arthritis (RA) and psoriatic arthritis (PsA) (p<0.05). Bulk RNA-seq was performed on altered SF CD8 T cell subsets from ICI-A, RA and PsA to investigate their transcriptomic features. Cytokine profile and pathways enriched in ICI-A CD8 T cells were examined using differentially expressed genes, intracellular staining, and in vitro culture. TCR clonotypes were examined using single cell RNA-seq of T cells from synovial fluid, tissue and blood of ICI-A.

Results

Compared to the autoimmune arthritides RA and PsA, ICI-arthritis joints contained an expanded CD38hi CD127- CD8+ T cell subset that displays cytotoxic, effector, and interferon (IFN) response signatures. Exposure of synovial T cells to Type I IFN, more so than IFN-γ, induced the CD38hi cytotoxic phenotype. Single cell transcriptomic and T cell repertoire (TCR) analyses indicated that the abundance of CD38hi CD8 T cells in ICI-arthritis resulted from proliferation of a limited number of clones. The CD38hi population appeared distinct from dysfunctional T cells and clonally most related to TCF7+ memory populations. Comparison of synovial tissue from bilateral knees of the same patient demonstrated considerable sharing of TCR clonotypes among CD38hi CD8 T cells between the two joints. Further, TCR clonotypes expanded in synovial fluid of ICI-arthritis patients were detected in circulating T cells, and circulating CD38hi CD8 T cells are also expanded in ICI-arthritis patients.

Conclusion

These results define a distinct CD8 T cell subset in the synovial fluid and in the circulation of patients with ICI-A that may be directly activated by ICI therapy to mediate a tissue-specific autoimmune response.

Disclosure of Interests

None declared.

OP0328 A UNIQUE PD1+CD38+ CD8+ T CELL POPULATION CHARACTERIZES CHECKPOINT INHIBITOR-ASSOCIATED INFLAMMATORY ARTHRITIS

Background:

Immune checkpoint inhibitors (CI) are monoclonal antibodies that block CTLA-4, PD-1 or PD-L1, resulting in cytotoxic T cell activation in the tumor microenvironment. They have revolutionized the management of metastatic cancer but unleash “immune related adverse events” in > 80% of treated patients, including inflammatory arthritis in ~4%1. CI-associated arthritis (CI-A) often presents as a symmetrical polyarthritis, phenotypically indistinguishable from rheumatoid arthritis (RA), but whether it shares cellular and molecular features of RA has not been determined.

Objectives:

To compare synovial fluid (SF) T cell populations from CI-A patients to those in patients with RA, phenotypically and functionally.

Methods:

We immunophenotyped SF mononuclear cells from patients with CI-A caused by anti-PD-(L)1 therapy (n=9), seropositive RA (n=5), and psoriatic arthritis (PsA) (n=5) using a 39-marker mass cytometry (CyTOF) panel. FlowSOM was used to cluster CD4 and CD8 T cells into 15 ‘metaclusters’ based on multidimensional phenotypes. We used Kruskal-Wallis or Mann-Whitney tests to identify significantly altered populations (p<0.05), which we confirmed by biaxial gating. Flow cytometry was used to confirm SF findings in an independent cohort, and to identify cells of interest in peripheral blood. Cytokine staining was performed on sorted T cells populations after CDCD3/CD28 stimulation for 72 hours, followed by 4 hour PMA/ION+BRA/MON restimulation.

Results:

In CI-A patients, T cells represented 50% of SF mononuclear cells (53% CD4, 40% CD8), followed by monocytes (24%) and NK cells (8%), comparable to RA and PsA. However, FlowSOM analysis revealed expansion of a distinct population of PD-1+CD38hiCD127-CD8 T cells (CD8 metacluster2) (Fig. 1). These cells comprised 30% of CD8+ SF T cells in CI-A, a 3.4-fold increase over RA/PsA, p=0.0002 (Fig. 2). Over 40% of these cells expressed Ki67 in CI-A, suggesting active proliferation. Flow cytometry on SF cells from an independent cohort of CI-A patients (n= 5) and RA/PsA comparators (n= 9) confirmed our findings. PD-1+CD38hiCD127-CD8 T cells were also expanded in the blood of CI-A patients, where they represented 4.6% of CD8 Tcells, a 2.8-fold increase over RA, p = 0.0057. In addition to expressing high levels of PD-1, CD38hiCD127-, these CD8 T cells express other immune checkpoint receptors including ICOS and TIGIT. After in vitro stimulation, CD38hiCD127-CD8 T cells produced granzyme B along with TNF and IFN-γ at comparable levels to other CD8 populations, suggesting that they are not functionally exhausted.

Figure 1.

Mass cytometry CD8+T cells (tSNE plots) with FlowSOM metaclusters.

Figure 2.

Synovial fluid PD-1+CD38hiCD127-CD8+T cells

FlowSOM analysis of SF CD4 T cells in CI-A patients revealed the expansion of a subpopulation of CD4 cells with a similar surface phenotype of PD-1+CD38hiCD127-(metacluster2, 10% of CD4s in CI-A, a 2.4-fold increase over RA/PsA, p=0.0047). In contrast, RA patients had a significantly expanded population of PD-1hiICOS+ CD4 T peripheral helper (Tph) cells (metacluster5, 30% of CD4s in RA, p=0.006), but these cells were not expanded in CI-A (Fig 3).

Figure 3.

Synovial fluid CD4+T peripheral helper cells

Conclusion:

CyTOF analysis of SF revealed a uniquely expanded PD-1+CD38hiCD127-CD8 T cell population in CI-A not present in RA or PsA, and a similar PD-1+CD38hiCD127-CD4 T cell population. These cells may contribute to the amplified immune response seen in CI-A patients. Further functional and transcriptional analysis of these cells will help to elucidate their function may reveal key mechanisms driving CI-associated immune related adverse events.

References:

[1]Kostine M. Ann Rheum Dis 2018;77(3):393-398

Disclosure of Interests:

Runci Wang: None declared, Karmela Kim Chan: None declared, Amy Cunningham-Bussel: None declared, Laura Donlin Consultant of: Consultant – Genentech/Roche, Gregory Vitone: None declared, Aidan Tirpack: None declared, Caroline Benson: None declared, Gregory Keras: None declared, A. Helena Jonsson: None declared, Michael Brenner: None declared, Anne Bass: None declared, Deepak Rao Grant/research support from: Has received research grant support from Celgene and Merck., Consultant of: Has received consulting fees or honoraria from Merck, Pfizer, GlaxoSmithKine, Bristol-Myers Squibb, Janssen, and Scipher Medicine

Abstract P3-05-07: Improving CAR T cell function by reversing the immunosuppressive tumor environment of breast cancer

Adoptive transfer of T cells redirected to tumor-associated antigens (TAAs) by expression of chimeric antigen receptors (CARs) can produce tumor responses, even in patients with resistant malignancies. To target breast cancer, we generated T cells expressing a CAR directed to the TAA mucin-1 (MUC1). T cells expressing this CAR (86±1.9%, n=5) specifically killed MUC1-expressing cells (MDA-MB-468 – 45.9±7.3%, MCF-7 – 36.8±3.6) but not MUC1(-) 293T cells (3.7±1.6% specific lysis, 20:1 E:T, n=3). Although these CAR T cells had potent anti-tumor activity against breast cancer cells, when exposed to the Th2-polarizing cytokine IL4 [which is upregulated in tumor samples (Oncomine, p&lt;0.05)] we observed a dramatic reduction in their cytolytic potential [IL2 - 45.9±7.3% vs IL4 - 11.3±3.7% specific lysis, 20:1 E:T ratio, n=4]. Thus, to protect our CAR.MUC1 T cells from the negative influences of IL4, we generated an inverted cytokine receptor (ICR) in which the IL4 receptor exodomain was fused to the IL7 receptor endodomain (4/7 ICR). Transgenic expression of this molecule in CAR.MUC1 T cells (55±4.8% double positive cells, n=5), restored the cytolytic function of CAR T cells (30.9±8.1% specific lysis, 20:1 E:T, n=3). Next, to determine the long term effects of this modification we co-cultured transgenic T cells with MUC1+ tumor cells and measured tumor and T cells numbers. In the presence of IL4, only double positive (CAR.MUC1-4/7) T cells expanded and eliminated the tumors in vitro and in vivo. However, upon tumor elimination, transgenic T cells rapidly contracted, demonstrating the antigen- and cytokine-dependence of the product. In conclusion, CAR.MUC1-4/7 T cells can effectively target breast cancer cells and retain their cytotoxic function even in the IL4-rich tumor microenvironment.

Citation Format: Bajgain P, Tawinwung S, Watanabe N, Sukumaran S, Anurathapan U, Heslop HE, Rooney CM, Brenner M, Leen AM, Vera JF. Improving CAR T cell function by reversing the immunosuppressive tumor environment of breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-05-07.

Sediment biomarkers elucidate the Holocene ontogeny of a shallow lake

We carried out geochemical analyses on a sediment core from Lake Harris, Florida (USA) to identify sources of organic matter to the sediment throughout the Holocene, and relate changes in those sources to shifts in past climate and environmental conditions. We hypothesized that the sources of organic matter changed in response to regional hydrologic shifts following de-glaciation, and to human population expansion in the state during the 20th century. Hydroclimate shifts in Florida were related to: 1) a steady rise in relative sea level and the fresh water table that began in the early Holocene, 2) wetland formation and expansion ca. 5,000 cal yrs BP, and 3) the onset of the modern El Niño (ENSO) cycle ~3,000 cal yrs BP. Stratigraphic changes in sediment variables from Lake Harris reflect each of these hydroclimate periods. Early in the Holocene, Lake Harris was a marsh-like system in a relatively dry, open-prairie environment. Organic sediments deposited at that time were derived largely from terrestrial sources, as inferred from high TOC/TN ratios, a dominance of longer-chain of n-alkanes (n-C29-31), relatively negative organic carbon isotope values (δ13CTOC), and low biogenic silica concentrations. In the middle Holocene, a positive shift in δ13CTOC coincided with the onset of wetter conditions in Florida. Submerged macrophyte biomarkers (n-C21-23) dominated, and during that period bulk organic carbon isotope values were most similar to δ13C values of mid-chain-length n-alkanes. In the late Holocene, δ13CTOC values declined, CaCO3 levels decreased to trace amounts, organic carbon concentrations increased and diatom biogenic silica concentrations increased from 10 to 120 mg g-1. Around 2,900 cal yrs BP, the effects of ENSO intensified and many Florida lakes deepened to their current limnetic state. Concentrations of algal and cyanobacterial biomarkers in the Lake Harris core increased by orders of magnitude after about AD 1940, in response to human-induced eutrophication, an inference supported by values of δ15N that fluctuate around zero.

Tackling the burden of the hepatitis C virus in the UK: characterizing and assessing the clinical and economic consequences

OBJECTIVES

The hepatitis C virus (HCV) remains a significant public health issue. This study aimed to quantify the clinical and economic burden of chronic hepatitis C in the UK, stratified by disease severity, age and awareness of infection, with concurrent assessment of the impact of implementing a treatment prioritization approach.

STUDY DESIGN AND METHODS

A previously published back projection, natural history and cost-effectiveness HCV model was adapted to a UK setting to estimate the disease burden of chronic hepatitis C and end-stage liver disease (ESLD) between 1980 and 2035. A published meta-regression analysis informed disease progression, and UK-specific data informed other model inputs.

RESULTS

At 2015, prevalence of chronic hepatitis C is estimated to be 241,487 with 22.20%, 33.72%, 17.22%, 16.67% and 10.19% of patients in METAVIR stages F0, F1, F2, F3 and F4, respectively, but is estimated to fall to 193,999 by 2035. ESLD incidence is predicted to peak in 2031. Assuming all patients are diagnosed and treatment is prioritized in F3 and F4 using highly efficacious direct-acting antiviral (DAA) regimens, a 69.85% reduction in ESLD incidence is predicted between 2015 and 2035, and the cumulative discounted medical expenditure associated with the lifetime management of incident ESLD events is estimated to be £1,202,827,444.

CONCLUSIONS

The prevalence of chronic hepatitis C is expected to fall in coming decades; however, the ongoing financial burden is expected to be high due to an increase in ESLD incidence. This study highlights the significant costs of managing ESLD that are likely to be incurred without the employment of effective treatment approaches.

Play distraction versus pharmacological treatment to reduce anxiety levels in children undergoing day surgery: a randomized controlled non-inferiority trial

BACKGROUND

Perioperative experience can be one of the most distressful experiences in a child's life if not managed properly by healthcare professionals. Its consequences can extend well beyond surgery and recovery into the child's future life. Healthcare professionals have a responsibility to decrease the anxiety associated with this experience, improve the child's and the parent's experience and prevent negative consequences. This has traditionally been performed through pharmacological treatment which might have negative side effects. More developmentally appropriate distraction methods are currently being trialled globally to augment the evidence that supports their use as a similarly efficient alternative.

OBJECTIVES

The aim of this study was to explore the efficiency of storytelling, pictures and colouring activities as an anxiolytic intervention in comparison to the traditional pharmacological premedication technique in a non-inferiority study.

STUDY DESIGN

A randomized non-inferiority controlled trial was carried out in 168 children scheduled for day surgery. Children's perioperative anxiety was assessed by a trained anaesthetist using the modified Yale Preoperative Assessment Scale and by parents using the State-Trait Anxiety Inventory for Children. Children's vital signs were also collected preoperatively during the induction period and during the recovery period.

RESULTS

The primary endpoint, which is non-inferiority in terms of anxiety as per Yale Preoperative Assessment Scale survey between play distraction and preoperative medication, was met [average score 10.95 vs. 10.94, respectively, 95% confidence interval (-0.35; 0.37); P = 0.941]. Moreover, anxiety scores of both the intervention and the control group were quite comparable as per STAIC survey [20.90 vs. 20.73, respectively, 95% confidence interval (-0.52; 0.88); P = 0.708] and in terms of vital signs.

CONCLUSION

The results indicate that the distraction technique employed can be considered as an efficient alternative to traditional pharmacological premedication for children undergoing day surgery.

Severe congenital malformations, family functioning and parents' separation/divorce: a longitudinal study

BACKGROUND

We aim to explore the association of a severe congenital malformation (SCM) with postnatal family functioning and parents' separation/divorce and to examine if this association might be moderated by birth order of the child and parental level of education. SCM refers to malformations that, without medical intervention, cause handicap or death.

METHODS

Using the Quebec Longitudinal Study of Child Development, an ongoing population-based birth cohort study initiated in 1998, we compared 1675 families of children with and without a SCM to identify if having a child with a SCM was associated with maternal perception of family functioning. We examined if an SCM was associated with parents' separation and examined parents' education level and birth order of the children to evaluate whether these factors had any moderating effect on the results.

RESULTS

There were no significant differences in family functioning between families with and without a SCM child at 5 and 17 months. At 5 months, family functioning was significantly better (P = 0.03) for families with a SCM firstborn child than for families with a SCM child that is not firstborn. For parental separation, no significant differences were observed at 5 and 29 months and 4 years. No significant moderating effects were observed for birth order and parental education on parental separation.

CONCLUSIONS

Families of children with a SCM do not appear to be at higher risk of family dysfunction within the first 17 months after birth nor of parental separation within the first 4 years after birth. Family functioning tends to be worst in families where the child with SCM is the second or subsequent child born.

Patients with manifest hepatic encephalopathy can reveal impaired thermal perception

OBJECTIVES

Previous evoked potential studies indicated central impairments of somatosensory function in patients suffering from hepatic encephalopathy (HE). The aim of this study was to quantify the somatosensory perception in patients with minimal and overt HE.

MATERIALS AND METHODS

Forty-two patients with liver cirrhosis and HE up to grade 2 and 12 age-matched healthy controls underwent a comprehensive graduation of HE including the West Haven criteria, the critical flicker frequency (CFF), and neuropsychometric testing. Quantitative sensory testing, standardized by the German Research Network on Neuropathic Pain, was performed on both hands.

RESULTS

Pain and mechanical detection thresholds were unchanged in HE. Tests of thermal processing revealed that patients with HE of grade 2 perceive cold at lower temperatures (cold detection threshold) and need a higher temperature difference to distinguish between warm and cold (thermal sensory limen). These impairments correlated with the CFF. A correction for attention deficits by performing partial correlations using neuropsychometric test results canceled these correlations.

CONCLUSIONS

The present findings demonstrate an impairment of temperature perception in HE. The extent of this impairment correlates with HE severity as quantified by the CFF. The attenuation of the correlations after correction for attention deficits suggests a strong role of attention deficits for the impaired thermal perception. Thus, it provides initial evidence for a central impairment of thermal processing in HE due to alterations in high-level processes rather than due to peripheral neuropathic processes, which are a frequent complication in patients with liver cirrhosis.

Endovascular therapy in trauma

The practice of medicine has experienced a revolution in the use of catheter-based or endovascular techniques to manage age-related vascular disease over the past 15 years. In many scenarios the less invasive, endovascular method is associated with reduced morbidity and mortality than the traditional open surgical approach. Although somewhat delayed, the use of endovascular approaches in the management of certain trauma scenarios has also increased dramatically. With improvements in catheter-based and imaging technologies and a broader acceptance of the value of the endovascular approach, this trend is likely to continue to the benefit of patients. The use of endovascular techniques in trauma can be considered in three broad categories: (1) large-vessel repair (e.g. covered stent repair), (2) mid- to small-vessel hemostasis (e.g. coils, plugs, and hemostatic agents), and (3) large-vessel balloon occlusion for resuscitation (e.g. resuscitative endovascular balloon occlusion of the aorta). While not exclusive, these categories provide a framework from which to consider establishing a trauma-specific endovascular inventory and performance of these techniques in the setting of severe injury. The aim of this review is to use this framework to provide a current appraisal of endovascular techniques to manage various forms: vascular injury, bleeding, and shock; including injury patterns in which an endovascular approach is established and scenarios in which it is nascent and evolving.

The vitamin B12 analog cobinamide is an effective hydrogen sulfide antidote in a lethal rabbit model

BACKGROUND AND PURPOSE

Hydrogen sulfide (H2S) is a highly toxic gas for which no effective antidotes exist. It acts, at least in part, by binding to cytochrome c oxidase, causing cellular asphyxiation and anoxia. We investigated the effects of three different ligand forms of cobinamide, a vitamin B12 analog, to reverse sulfide (NaHS) toxicity.

METHODS

New Zealand white rabbits received a continuous intravenous (IV) infusion of NaHS (3 mg/min) until expiration or a maximum 270 mg dose. Animals received six different treatments, administered at the time when they developed signs of severe toxicity: Group 1-saline (placebo group, N = 9); Group 2--IV hydroxocobalamin (N = 7); Group 3--IV aquohydroxocobinamide (N = 6); Group 4--IV sulfitocobinamide (N = 6); Group 5--intramuscular (IM) sulfitocobinamide (N = 6); and Group 6-IM dinitrocobinamide (N = 8). Blood was sampled intermittently, and systemic blood pressure and deoxygenated and oxygenated hemoglobin were measured continuously in peripheral muscle and over the brain region; the latter were measured by diffuse optical spectroscopy (DOS) and continuous wave near infrared spectroscopy (CWNIRS).

RESULTS

Compared with the saline controls, all cobinamide derivatives significantly increased survival time and the amount of NaHS that was tolerated. Aquohydroxocobinamide was most effective (261.5 ± 2.4 mg NaHS tolerated vs. 93.8 ± 6.2 mg in controls, p < 0.0001). Dinitrocobinamide was more effective than sulfitocobinamide. Hydroxocobalamin was not significantly more effective than the saline control.

CONCLUSIONS

Cobinamide is an effective agent for inhibiting lethal sulfide exposure in this rabbit model. Further studies are needed to determine the optimal dose and form of cobinamide and route of administration.

Multi-biomarker approach using the blue mussel (Mytilus edulis L.) to assess the quality of marine environments: season and habitat-related impacts

Using a comprehensive approach, intertidal, near- and offshore sites in the German Bight were analysed for their environmental quality by assessing the health of blue mussels (Mytilus edulis). During a ten month sampling period mussels were studied with a set of biomarkers comprising lysosomal membrane stability and accumulation of lipofuscin, supplemented by biomarkers indicating nutritional status such as neutral lipids and glycogen in the cells of the digestive gland. Data were analysed in relation to sex, gonadal status, condition index and for the presence of parasites, to determine the overall health status of mussels at the respective sites. Mussels from all sites showed clear signs of stress, indicating an inferior environmental quality throughout the southern German Bight. Further, habitat characteristics such as inundation time and growing on- or off-bottom, as well as seasonal factors, can clearly influence the response of biomarkers in mussels exposed to similar levels of chemical environmental stress.

Distribution of supercurrent switching in graphene under the proximity effect

We study the stochastic nature of switching current in hysteretic current-voltage characteristics of superconductor-graphene-superconductor junctions. We find that the dispersion of the switching current distribution scales with temperature as σ(I) proportional to T(α(G)) with α(G) as low as 1/3. This observation is in sharp contrast to the known Josephson junction behavior where σ(I) proportional to T(α(J)) with α(J)=2/3. We propose an explanation using a generalized version of Kurkijärvi's theory for the flux stability in rf-SQUID and attribute this anomalous effect to the temperature dependence of the critical current which persists down to low temperatures.

[Asymptomatic facial infiltrated papules in an HIV-positive male]

A 65 year old HIV-infected patient (CDC A2, diagnosed in 07/2008) presented with facial, erythematous infiltrated papular lesions. Consistent with progressive immunodeficiency a low CD4+ T-cell count and an increase of the viral load was seen simultaneously and an eosinophilic pustular folliculitis (EPF) was assumed. Though, the lesional biopsy revealed a follicular eosinophilic infiltration and endotrichial hyphae, proving for an infiltrating dermatophytosis. This shows how an infiltrating Tinea faciei is mimicking clinically and histologically an HIV-associated EPF of the face.

GFAP mutations, age at onset, and clinical subtypes in Alexander disease

OBJECTIVE

To characterize Alexander disease (AxD) phenotypes and determine correlations with age at onset (AAO) and genetic mutation. AxD is an astrogliopathy usually characterized on MRI by leukodystrophy and caused by glial fibrillary acidic protein (GFAP) mutations.

METHODS

We present 30 new cases of AxD and reviewed 185 previously reported cases. We conducted Wilcoxon rank sum tests to identify variables scaling with AAO, survival analysis to identify predictors of mortality, and χ(2) tests to assess the effects of common GFAP mutations. Finally, we performed latent class analysis (LCA) to statistically define AxD subtypes.

RESULTS

LCA identified 2 classes of AxD. Type I is characterized by early onset, seizures, macrocephaly, motor delay, encephalopathy, failure to thrive, paroxysmal deterioration, and typical MRI features. Type II is characterized by later onset, autonomic dysfunction, ocular movement abnormalities, bulbar symptoms, and atypical MRI features. Survival analysis predicted a nearly 2-fold increase in mortality among patients with type I AxD relative to those with type II. R79 and R239 GFAP mutations were most common (16.6% and 20.3% of all cases, respectively). These common mutations predicted distinct clinical outcomes, with R239 predicting the most aggressive course.

CONCLUSIONS

AAO and the GFAP mutation site are important clinical predictors in AxD, with clear correlations to defined patterns of phenotypic expression. We propose revised AxD subtypes, type I and type II, based on analysis of statistically defined patient groups.

Cardiovascular assessment in children: assessing pulse and blood pressure

Cardiovascular assessment is an important nursing skill in the assessment and management of acutely ill children and children with chronic conditions. This article outlines the differences in the cardiovascular systems of infants, children and adults, and explains how to provide circulatory assessment in children, focusing on assessing pulse and blood pressure.

What are melanocytes really doing all day long...?

Everyone knows and seems to agree that melanocytes are there to generate melanin - an intriguing, but underestimated multipurpose molecule that is capable of doing far more than providing pigment and UV protection to skin (1). What about the cell that generates melanin, then? Is this dendritic, neural crest-derived cell still serving useful (or even important) functions when no-one looks at the pigmentation of our skin and its appendages and when there is essentially no UV exposure? In other words, what do epidermal and hair follicle melanocytes do in their spare time - at night, under your bedcover? How much of the full portfolio of physiological melanocyte functions in mammalian skin has really been elucidated already? Does the presence or absence of melanocytes matter for normal epidermal and/or hair follicle functions (beyond pigmentation and UV protection), and for skin immune responses? Do melanocytes even deserve as much credit for UV protection as conventional wisdom attributes to them? In which interactions do these promiscuous cells engage with their immediate epithelial environment and who is controlling whom? What lessons might be distilled from looking at lower vertebrate melanophores and at extracutaneous melanocytes in the endeavour to reveal the 'secret identity' of melanocytes? The current Controversies feature explores these far too infrequently posed, biologically and clinically important questions. Complementing a companion viewpoint essay on malignant melanocytes (2), this critical re-examination of melanocyte biology provides a cornucopia of old, but under-appreciated concepts and novel ideas on the slowly emerging complexity of physiological melanocyte functions, and delineates important, thought-provoking questions that remain to be definitively answered by future research.

Targeted treatment of pyoderma gangrenosum in PAPA (pyogenic arthritis, pyoderma gangrenosum and acne) syndrome with the recombinant human interleukin-1 receptor antagonist anakinra

The triad of sterile pyogenic arthritis, pyoderma gangrenosum and acne is known by the acronym of PAPA syndrome. It is a rare autosomal dominant disease of early onset. The treatment of pyoderma gangrenosum is challenging as there is often only partial response to systemic glucocorticosteroids and immunosuppressive therapies. We report the rapid and lasting response of pyoderma gangrenosum to the targeted treatment with the recombinant human interleukin-1 receptor antagonist (rHuIL-1Ra) anakinra in a patient with PAPA syndrome.

Hemodynamic changes in rat leg muscles during tourniquet-induced ischemia-reperfusion injury observed by near-infrared spectroscopy

In this study, we hypothesized that non-invasive continuous wave near-infrared spectroscopy (CWNIRS) can determine the severity or reversibility of muscle damage due to ischemia/reperfusion (I/R), and the results will be highly correlated with those from physical examination and histological analysis. To test this hypothesis, we performed CWNIRS measurements on two groups of male Sprague-Dawley rats ( approximately 400 g) that underwent 2 h (n = 6) or 3 h (n = 7) of pneumatic tourniquet application (TKA). Tissue oxyhemoglobin [HbO(2)] and deoxyhemoglobin [Hb] concentration changes were monitored during the 2 h or 3 h of 250 mmHg TKA and for an additional 2 h post-TKA. Rats were euthanized 24 h post-TKA and examined for injury, edema and viability of muscles. Contralateral muscles served as controls for each animal. In both groups, [HbO(2)] dropped immediately, then gradually decreased further after TKA and then recovered once the tourniquet was released. However, releasing after 2 h of TKA caused [HbO(2)] to overshoot above the baseline during reperfusion while the 3 h group continued to have lower [HbO(2)] than baseline. We found a significant correlation between the elapsed time from tourniquet release to the first recovery peak of [HbO(2)] and the muscle weight ratio between tourniquet and contralateral limb muscles (R = 0.86). Hemodynamic patterns from non-invasive CWNIRS demonstrated significant differences between 2 h and 3 h I/R. The results demonstrate that CWNIRS may be useful as a non-invasive prognostic tool for conditions involving vascular compromise such as extremity compartment syndrome.