A Family of Helminth Molecules that Modulate Innate Cell Responses via Molecular Mimicry of Host Antimicrobial Peptides

Over the last decade a significant number of studies have highlighted the central role of host antimicrobial (or defence) peptides in modulating the response of innate immune cells to pathogen-associated ligands. In humans, the most widely studied antimicrobial peptide is LL-37, a 37-residue peptide containing an amphipathic helix that is released via proteolytic cleavage of the precursor protein CAP18. Owing to its ability to protect against lethal endotoxaemia and clinically-relevant bacterial infections, LL-37 and its derivatives are seen as attractive candidates for anti-sepsis therapies. We have identified a novel family of molecules secreted by parasitic helminths (helminth defence molecules; HDMs) that exhibit similar biochemical and functional characteristics to human defence peptides, particularly CAP18. The HDM secreted by Fasciola hepatica (FhHDM-1) adopts a predominantly α-helical structure in solution. Processing of FhHDM-1 by F. hepatica cathepsin L1 releases a 34-residue C-terminal fragment containing a conserved amphipathic helix. This is analogous to the proteolytic processing of CAP18 to release LL-37, which modulates innate cell activation by classical toll-like receptor (TLR) ligands such as lipopolysaccharide (LPS). We show that full-length recombinant FhHDM-1 and a peptide analogue of the amphipathic C-terminus bind directly to LPS in a concentration-dependent manner, reducing its interaction with both LPS-binding protein (LBP) and the surface of macrophages. Furthermore, FhHDM-1 and the amphipathic C-terminal peptide protect mice against LPS-induced inflammation by significantly reducing the release of inflammatory mediators from macrophages. We propose that HDMs, by mimicking the function of host defence peptides, represent a novel family of innate cell modulators with therapeutic potential in anti-sepsis treatments and prevention of inflammation

31st Annual Meeting and Associated Programs of the Society for Immunotherapy of Cancer (SITC 2016) : part two

Background The immunological escape of tumors represents one of the main ob- stacles to the treatment of malignancies. The blockade of PD-1 or CTLA-4 receptors represented a milestone in the history of immunotherapy. However, immune checkpoint inhibitors seem to be effective in specific cohorts of patients. It has been proposed that their efficacy relies on the presence of an immunological response. Thus, we hypothesized that disruption of the PD-L1/PD-1 axis would synergize with our oncolytic vaccine platform PeptiCRAd. Methods We used murine B16OVA in vivo tumor models and flow cytometry analysis to investigate the immunological background. Results First, we found that high-burden B16OVA tumors were refractory to combination immunotherapy. However, with a more aggressive schedule, tumors with a lower burden were more susceptible to the combination of PeptiCRAd and PD-L1 blockade. The therapy signifi- cantly increased the median survival of mice (Fig. 7). Interestingly, the reduced growth of contralaterally injected B16F10 cells sug- gested the presence of a long lasting immunological memory also against non-targeted antigens. Concerning the functional state of tumor infiltrating lymphocytes (TILs), we found that all the immune therapies would enhance the percentage of activated (PD-1pos TIM- 3neg) T lymphocytes and reduce the amount of exhausted (PD-1pos TIM-3pos) cells compared to placebo. As expected, we found that PeptiCRAd monotherapy could increase the number of antigen spe- cific CD8+ T cells compared to other treatments. However, only the combination with PD-L1 blockade could significantly increase the ra- tio between activated and exhausted pentamer positive cells (p= 0.0058), suggesting that by disrupting the PD-1/PD-L1 axis we could decrease the amount of dysfunctional antigen specific T cells. We ob- served that the anatomical location deeply influenced the state of CD4+ and CD8+ T lymphocytes. In fact, TIM-3 expression was in- creased by 2 fold on TILs compared to splenic and lymphoid T cells. In the CD8+ compartment, the expression of PD-1 on the surface seemed to be restricted to the tumor micro-environment, while CD4 + T cells had a high expression of PD-1 also in lymphoid organs. Interestingly, we found that the levels of PD-1 were significantly higher on CD8+ T cells than on CD4+ T cells into the tumor micro- environment (p < 0.0001). Conclusions In conclusion, we demonstrated that the efficacy of immune check- point inhibitors might be strongly enhanced by their combination with cancer vaccines. PeptiCRAd was able to increase the number of antigen-specific T cells and PD-L1 blockade prevented their exhaus- tion, resulting in long-lasting immunological memory and increased median survival

Visiting a fresh crater in Jezero with the Mars 2020 Perseverance Rover

Fresh craters provide an opportunity for close examination into the subsurface for landed missions. Adziilii crater is one of many fresh craters with extant ejecta within Jezero crater, the field site for the Mars 2020 Perseverance rover, formed in the unit termed Crater Floor- Fractured Rough (CF-Fr) which comprises much of the Jezero crater floor. This ~80x70 m elliptical crater has a depth/diameter ratio of 0.05 consistent with a low-angle secondary impact. Considering two similar appearing elongated impact craters lying to the southwest and southeast of the landing site, Adziilii crater is probably part of a secondary crater cluster. Meter scale-sized blocks line the Adziilii crater rim out to one crater radii to the north and south. Such asymmetric ejecta distribution is also related to shallow impact angles. Several sharp-rimmed kilometer diameter craters, for example the 2 km diameter Dacono crater east of Adziilii, are close enough to have been the source for ejecta blocks traveling at sub-hypervelocity. In the case of Dacono, a mere 320-350 m/s initial velocity at an ejection angle ranging from 30-45 degrees can loft an ejecta block the ~28 km distance to form Adziilii crater. Excavation depths of a crater this size are approximately 3-5 meters. Some larger ejecta blocks seen in Mastcam-Z images exhibit unique vesicular, sometimes ropey, textures different from the surrounding dusty low-lying rocks nearby and appear rougher than similar dark toned, smooth textured blocks examined by the Perseverance rover. Observations from the rover’s ground penetrating radar system (RIMFAX) reveal at least one higher density subsurface transition at about 3-5 m depth. Given the unique textures and excavation depths, there’s potential these blocks represent a unique buried surface. While the ejecta block textures are consistent with a geologic unit with a volcanic origin, as are several subsurface structures, the pattern is also consistent with aeolian erosion as seen in Gale Crater rocks at Rocknest. It is also possible the unique lithologic characteristics hint at impactor fragment survivability, more likely in a low velocity impact. However, if the source crater is local, the differences in lithology may be small or unobservable. Future observations of fresh impact craters along the rover's traverse should help elucidate more subsurface stratigraphy of the crater floor and other buried units examined by Perseverance at the surface

DIGITAL THREE-DIMENSIONAL MAPPING OF THE STRATIGRAPHIC ARCHITECTURE OF THE JEZERO WESTERN FAN FRONT

International audienceThe NASA Mars2020 rover Perseverance traversed series that represent the transition from crater floor lithologies to deposits of the Jezero western fan during its second Earth year of rover operations. During that time, the mission explored the exposed stratigraphic succession at the delta front, named the Shenandoah formation. The main science camera on the rover, Mastcam-Z, collects stereo-images of outcrops encountered in visible to near infrared wavelengths at focal lengths ranging from 34 to 110 mm. We use the Planetary Robotics Vision Processing and Planetary Robotics 3-D Viewer tools (PRoViP and PRo3D respectively) for processing, viewing and analysing correctly scaled and located 3-D digital outcrop models using Mastcam-Z stereo-images. Scaling and georeferencing of the models is achieved by incorporation of detailed camera models, image metadata detailing the camera pointing azimuths, focus, exposure and rover attititude, and spatial metadata obtained through incorporation and conversion of SPICE kernels. We can visualise these digital outcrop datasets overlain on high resolution orbital terrain data to measure the geometry of geological bodies and correlate observations between rover positions.Four cross-sections were constructed across the lower delta stratigraphy at the base of Hawksbill Gap and Cape Nukshak using data collected from 3D reconstructions of Mastcam-Z stereo-images and HiRISE topography. Lithological observations made from Mastcam-Z image mosaics were used to inform interpretations on multiple 3D reconstructions of stereo-image data. Stratigraphic boundaries based on team analyses, and the key dip and dip azimuth measurements, were mapped in PRo3D and plotted on topographic profiles to visualise the depositional architecture. Stratigraphic thicknesses were corrected for dip, where necessary, to build stratigraphic logs. The basal surfaces of the identified members which comprise the Shenandoah formation were correlated between the lines of section to illustrate the architectural variations across the delta front. We show that the overall boundaries of the stratigraphic units identified are sub-horizontal at the 100s of metre scale but show considerable variation in some locations at the sub-metre scale, largely as a result of soft sediment deformation, and the limited development of scours and low angle cross-stratification

CONSTRUCTING GEOLOGICAL CROSS-SECTIONS TO CONSTRAIN THE THREE-DIMENSIONAL STRATIGRAPHIC ARCHITECTURE OF THE JEZERO DELTA FRONT

International audienceThe NASA Mars2020 rover Perseverance has been traversing series that represent the transition from crater floor lithologies to deposits of the Jezero western delta since Sol 422 of rover operations [1]. During that time, the mission has explored the exposed stratigraphic succession at the delta front, named the Shenandoah formation [2]. Here we analyse Mastcam-Z mosaics and 3D data products derived from Planetary Robotics processing and viewing tools (PRoViP and PRo3D [3]) to map the 3D geometry of key stratigraphic boundaries and document the 3D stratigraphic architecture at the sub-km- to m-scale within the Shenandoah formation

CONSTRUCTING GEOLOGICAL CROSS-SECTIONS TO CONSTRAIN THE THREE-DIMENSIONAL STRATIGRAPHIC ARCHITECTURE OF THE JEZERO DELTA FRONT

International audienceThe NASA Mars2020 rover Perseverance has been traversing series that represent the transition from crater floor lithologies to deposits of the Jezero western delta since Sol 422 of rover operations [1]. During that time, the mission has explored the exposed stratigraphic succession at the delta front, named the Shenandoah formation [2]. Here we analyse Mastcam-Z mosaics and 3D data products derived from Planetary Robotics processing and viewing tools (PRoViP and PRo3D [3]) to map the 3D geometry of key stratigraphic boundaries and document the 3D stratigraphic architecture at the sub-km- to m-scale within the Shenandoah formation