Connecting photometric and spectroscopic granulation signals with CHEOPS and ESPRESSO

Context. Stellar granulation generates fluctuations in photometric and spectroscopic data whose properties depend on the stellar type, composition, and evolutionary state. Characterizing granulation is key for understanding stellar atmospheres and detecting planets. Aims. We aim to detect the signatures of stellar granulation, link spectroscopic and photometric signatures of convection for main-sequence stars, and test predictions from 3D hydrodynamic models. Methods. For the first time, we observed two bright stars (Teff = 5833 and 6205 K) with high-precision observations taken simultaneously with CHEOPS and ESPRESSO. We analyzed the properties of the stellar granulation signal in each individual dataset. We compared them to Kepler observations and 3D hydrodynamic models. While isolating the granulation-induced changes by attenuating and filtering the p-mode oscillation signals, we studied the relationship between photometric and spectroscopic observables. Results. The signature of stellar granulation is detected and precisely characterized for the hotter F star in the CHEOPS and ESPRESSO observations. For the cooler G star, we obtain a clear detection in the CHEOPS dataset only. The TESS observations are blind to this stellar signal. Based on CHEOPS observations, we show that the inferred properties of stellar granulation are in agreement with both Kepler observations and hydrodynamic models. Comparing their periodograms, we observe a strong link between spectroscopic and photometric observables. Correlations of this stellar signal in the time domain (flux versus radial velocities, RV) and with specific spectroscopic observables (shape of the cross-correlation functions) are however difficult to isolate due to S/N dependent variations. Conclusions. In the context of the upcoming PLATO mission and the extreme precision RV surveys, a thorough understanding of the properties of the stellar granulation signal is needed. The CHEOPS and ESPRESSO observations pave the way for detailed analyses of this stellar process

The CHEOPS mission

The CHaracterising ExOPlanet Satellite (CHEOPS) was selected in 2012, as the first small mission in the ESA Science Programme and successfully launched in December 2019. CHEOPS is a partnership between ESA and Switzerland with important contributions by ten additional ESA Member States. CHEOPS is the first mission dedicated to search for transits of exoplanets using ultrahigh precision photometry on bright stars already known to host planets. As a follow-up mission, CHEOPS is mainly dedicated to improving, whenever possible, existing radii measurements or provide first accurate measurements for a subset of those planets for which the mass has already been estimated from ground-based spectroscopic surveys and to following phase curves. CHEOPS will provide prime targets for future spectroscopic atmospheric characterisation. Requirements on the photometric precision and stability have been derived for stars with magnitudes ranging from 6 to 12 in the V band. In particular, CHEOPS shall be able to detect Earth-size planets transiting G5 dwarf stars in the magnitude range between 6 and 9 by achieving a photometric precision of 20 ppm in 6 hours of integration. For K stars in the magnitude range between 9 and 12, CHEOPS shall be able to detect transiting Neptune-size planets achieving a photometric precision of 85 ppm in 3 hours of integration. This is achieved by using a single, frame-transfer, back-illuminated CCD detector at the focal plane assembly of a 33.5 cm diameter telescope. The 280 kg spacecraft has a pointing accuracy of about 1 arcsec rms and orbits on a sun-synchronous dusk-dawn orbit at 700 km altitude. The nominal mission lifetime is 3.5 years. During this period, 20% of the observing time is available to the community through a yearly call and a discretionary time programme managed by ESA.Comment: Submitted to Experimental Astronom

NASH limits anti-tumour surveillance in immunotherapy-treated HCC.

Hepatocellular carcinoma (HCC) can have viral or non-viral causes1-5. Non-alcoholic steatohepatitis (NASH) is an important driver of HCC. Immunotherapy has been approved for treating HCC, but biomarker-based stratification of patients for optimal response to therapy is an unmet need6,7. Here we report the progressive accumulation of exhausted, unconventionally activated CD8+PD1+ T cells in NASH-affected livers. In preclinical models of NASH-induced HCC, therapeutic immunotherapy targeted at programmed death-1 (PD1) expanded activated CD8+PD1+ T cells within tumours but did not lead to tumour regression, which indicates that tumour immune surveillance was impaired. When given prophylactically, anti-PD1 treatment led to an increase in the incidence of NASH-HCC and in the number and size of tumour nodules, which correlated with increased hepatic CD8+PD1+CXCR6+, TOX+, and TNF+ T cells. The increase in HCC triggered by anti-PD1 treatment was prevented by depletion of CD8+ T cells or TNF neutralization, suggesting that CD8+ T cells help to induce NASH-HCC, rather than invigorating or executing immune surveillance. We found similar phenotypic and functional profiles in hepatic CD8+PD1+ T cells from humans with NAFLD or NASH. A meta-analysis of three randomized phase III clinical trials that tested inhibitors of PDL1 (programmed death-ligand 1) or PD1 in more than 1,600 patients with advanced HCC revealed that immune therapy did not improve survival in patients with non-viral HCC. In two additional cohorts, patients with NASH-driven HCC who received anti-PD1 or anti-PDL1 treatment showed reduced overall survival compared to patients with other aetiologies. Collectively, these data show that non-viral HCC, and particularly NASH-HCC, might be less responsive to immunotherapy, probably owing to NASH-related aberrant T cell activation causing tissue damage that leads to impaired immune surveillance. Our data provide a rationale for stratification of patients with HCC according to underlying aetiology in studies of immunotherapy as a primary or adjuvant treatment

Ablative techniques in Psoriasis vulgaris resistant to conventional therapies

BACKGROUND: Treatment of patients with psoriasis vulgaris exhibiting only solitary plaque-stage lesions might become difficult since topical treatments often fail and systemic therapies seem inappropriate. OBJECTIVE: We evaluated the feasibility of ablative techniques in this clinical setting comparing dermatome shaving to the application of an Er:YAG laser. METHODS: Six patients were treated by means of dermatome shaving; in four of these patients additional lesions were ablated utilizing an Er:YAG laser (2 J, 10 Hz, 5 mm spot size). RESULTS: Four of six patients experienced complete clearance of the lesions treated, three of the four patients receiving additional Er:YAG treatment also showed a complete clinical response. CONCLUSION: Our observations document that removal of epidermis and the papillary dermis is effective in treating recalcitrant psoriatic plaques. The Er:YAG laser represents a state-of-the-art device for performing this task. The beneficial effect on skin might be due to clearance of the putative autoantigen along with a considerable part of the potential effector cell population

Expression of the basal cell adhesion molecule (B-CAM) in normal and diseased human skin

The basal cell adhesion molecule (B-CAM) is a 90-kD cell surface glycoprotein with a characteristic immunoglobulin domain structure. The pattern of B-CAM expression in cultured cells suggests that the molecule is associated with a substrate-adherent growth pattern in some lineages. We investigated the expression of B-CAM in normal and diseased human epidermis by means of immunohistochemistry employing a single batch of high-titer mouse monoclonal antibody G253. Snap-frozen biopsy material from normal skin (n = 8), psoriasis (n = 5), contact dermatitis (n = 6), basal cell carcinoma (n = 5) and fetal skin (n = 6) was studied. In normal human skin, B-CAM was found in varying degrees throughout the epidermis with a preference for suprabasal expression, hair follicles were regularly of a B-CAM-positive phenotype. There were no qualitative differences with regard to the B-CAM expression pattern in normal skin in comparison to psoriasis and contact dermatitis. In contrast, fetal skin (15th to 18th week of gestation) was characterized by B-CAM-positive cells in the basal layer of the epidermis as well as in the outer root sheath of hair follicles. Basal cell carcinomas also regularly expressed high levels of B-CAM. A strong B-CAM-positive phenotype can be found in the outer root sheath of hair follicles of adult and fetal human skin as well as in fetal basal keratinocytes