The role of ACKR2 in inflammatory pathologies

Chemokines are a highly conserved family of chemoattractant cytokines that are key to the movement of cells around the body under both inflammatory and homeostatic conditions. Chemokines bind to seven transmembrane G protein coupled receptors that signal and induce cell movement upon ligand binding. As well as the ‘classical’ chemokine receptors, there also exists a family of atypical chemokine receptors that do not induce a canonical signalling response upon ligand binding. These atypical chemokine receptors (ACKR) have been shown to modify the chemokine response through processes such as the scavenging of inflammatory chemokines. One such receptor with this scavenging function is ACKR2 which has been shown to bind and internalise all of the inflammatory CC chemokines. The functional repertoire of ACKR2 continues to be expanded and it is now thought to have a role in inflammation, lymphatic drainage and lymphatic vessel development. It has been shown that the absence of this receptor results in impaired resolution of inflammation and, as a result, increased inflammatory pathologies in vivo. In models of skin inflammation a lack of ACKR2 has been shown to result in increased pathology and impaired inflammatory resolution. Multiple models of cutaneous inflammation, including excisional wound healing and chemically induced damage, were used to further investigate the role of ACKR2 in this context. Work on wound healing suggested that although ACKR2 appears to play no role in wound closure it does have a role in the formation of scar tissue in an excisional wound. Our data suggest that ACKR2 has a role in collagen deposition in developing and maturing scars. We also found that ACKR2 had a protective role in chemically-induced models of skin inflammation. We then looked at the role of ACKR2 in ocular inflammation. The main work performed in this section involved the use of the experimental autoimmune uveitis (EAU) model. Here we found that ACKR2 had a protective effective resulting in reduced pathology and infiltration of inflammatory leukocytes. This work also suggested, using in vitro analysis, that a human retinal pigmented epithelial cell line expresses functional ACKR2 protein and that our findings may be relevant to human disease. Finally we looked at the role of ACKR2 in the inflammatory autoimmune disease rheumatoid arthritis (RA). By taking samples of peripheral blood from RA patients we assessed the transcript levels of Ackr2 and correlated them with clinical measurements. Our findings suggested that, in patients with ‘well-controlled’ RA, there was an increase in the transcription of Ackr2 in peripheral blood leukocytes. Additional work using in vitro methods suggest that the hypoxic nature of the rheumatoid joint, and some of the drugs used to treat the disease, may increase the transcription of Ackr2. Overall the findings in this work suggest novel roles for ACKR2 in the skin and the eye. They also shed light on further environmental factors that may alter the local expression of ACKR2 in the rheumatoid joint. Taken together this work suggests that ACKR2 may have great therapeutic potential and, furthermore, this potential may be relevant to a wider range of tissues than previously thought

Atypical chemokine receptor ACKR2 controls branching morphogenesis in the developing mammary gland

Macrophages are important regulators of branching morphogenesis during development and postnatally in the mammary gland. Regulation of macrophage dynamics during these processes can therefore have a profound impact on development. We demonstrate here that the developing mammary gland expresses high levels of inflammatory CC-chemokines, which are essential in vivo regulators of macrophage migration. We further demonstrate that the atypical chemokine receptor ACKR2, which scavenges inflammatory CC-chemokines, is differentially expressed during mammary gland development. We have previously shown that ACKR2 regulates macrophage dynamics during lymphatic vessel development. Here, we extend these observations to reveal a novel role for ACKR2 in regulating the postnatal development of the mammary gland. Specifically, we show that Ackr2−/− mice display precocious mammary gland development. This is associated with increased macrophage recruitment to the developing gland and increased density of the ductal epithelial network. These data demonstrate that ACKR2 is an important regulator of branching morphogenesis in diverse biological contexts and provide the first evidence of a role for chemokines and their receptors in postnatal development processes

Automated gantry-type stitching system

A stitching system includes a gantry that is movable along a material support table. Mounted to the gantry are a plurality of stitching heads and bobbins. The stitching heads are individually controllable in a z-direction, and the bobbins are individually controllable in the z-direction. Each stitching head is paired with a bobbin. Each pair of stitching heads and the bobbins is controlled synchronously in the z-direction. The stitching system is well-suited for stitching preforms of aircraft wing covers and other preforms having variable thickness and compound, contoured three-dimensional surfaces

The atypical chemokine receptor ACKR2 is protective against sepsis

Sepsis is a systemic inflammatory response as a result of uncontrolled infections. Neutrophils are the first cells to reach the primary sites of infection and chemokines play a key role in recruiting neutrophils. However, in sepsis chemokines could also contribute to neutrophil infiltration to vital organs leading to multiple organ failure. ACKR2 is an atypical chemokine receptor, which can remove and degrade inflammatory CC chemokines. The role of ACK2 in sepsis is unknown. Using a model of cecal ligation and puncture (CLP), we demonstrate here that ACKR2 deficient (−/−) mice exhibited a significant reduction in the survival rate compared to similarly treated wild type (WT) mice. However, neutrophil migration to the peritoneal cavity and bacterial load were similar between WT and ACKR2−/− mice during CLP. In contrast, ACKR2−/− mice showed increased neutrophil infiltration and elevated CC chemokine levels in the lung, kidney and heart compared to the WT mice. In addition, ACKR2−/− mice also showed more severe lesions in the lung and kidney than those in the WT mice. Consistent with these results, WT mice under non-severe sepsis (90% survival) had higher expression of ACKR2 in these organs than mice under severe sepsis (no survival). Finally, the lungs from septic patients showed increased number of ACKR2+ cells compared to those of non-septic patients. Our data indicate that ACKR2 may have a protective role during sepsis, and the absence of ACKR2 leads to exacerbated chemokine accumulation, neutrophil infiltration and damage to vital organs

Elevated expression of the chemokine-scavenging receptor D6 is associated with impaired lesion development in psoriasis

D6 is a scavenging-receptor for inflammatory CC chemokines that are essential for resolution of inflammatory responses in mice. Here, we demonstrate that D6 plays a central role in controlling cutaneous inflammation, and that D6 deficiency is associated with development of a psoriasis-like pathology in response to varied inflammatory stimuli in mice. Examination of D6 expression in human psoriatic skin revealed markedly elevated expression in both the epidermis and lymphatic endothelium in "uninvolved" psoriatic skin (ie, skin that was more than 8 cm distant from psoriatic plaques). Notably, this increased D6 expression is associated with elevated inflammatory chemokine expression, but an absence of plaque development, in uninvolved skin. Along with our previous observations of the ability of epidermally expressed transgenic D6 to impair cutaneous inflammatory responses, our data support a role for elevated D6 levels in suppressing inflammatory chemokine action and lesion development in uninvolved psoriatic skin. D6 expression consistently dropped in perilesional and lesional skin, coincident with development of psoriatic plaques. D6 expression in uninvolved skin also was reduced after trauma, indicative of a role for trauma-mediated reduction in D6 expression in triggering lesion development. Importantly, D6 is also elevated in peripheral blood leukocytes in psoriatic patients, indicating that upregulation may be a general protective response to inflammation. Together our data demonstrate a novel role for D6 as a regulator of the transition from uninvolved to lesional skin in psoriasis

Cell-autonomous regulation of neutrophil migration by the D6 chemokine decoy receptor

Chemokines, acting on their cognate receptors on infiltrating leukocytes, drive the inflammatory response. We have been interested in determining roles and potential mechanisms for the atypical chemokine-scavenging receptor D6 in the regulation of inflammation. In this study, we show that a psoriasis-like pathology that arises in inflamed skins of D6-deficient mice is characterized by a massive and aberrant localization of neutrophils to the dermal/epidermal junction, which is associated with development of the pathology. Such misplacement of neutrophils is also seen with D6-deficient mice in other inflammatory models, suggesting a role for D6 in the spatial positioning of neutrophils within inflamed sites. We further show that D6 functions cell autonomously in this context and that D6, expressed by neutrophils, limits their migrational responses to CCR1 ligands such as CCL3. Our data therefore indicate that D6 is able to play a cell-autonomous role as a migratory rheostat restricting migration of D6-expressing cells such as neutrophils toward ligands for coexpressed inflammatory chemokine receptors. These data have important implications for our understanding of the roles for D6 in regulating inflammation and for our understanding of the control of spatial positioning of leukocytes at inflamed sites

Using remote-sensing technologies to find genetic variation in photosynthetic capacity in sorghum

Despite being a C4 crop sorghum (Sorghum bicolor (L.) Moench)) has a wide geographical distribution with adaptation to extreme climates such that its accessions are genetically diverse. Furthermore, the cereal has typically evolved in areas of limited water resources and thus alleles conferring growth under water limitation, such as alleles associated with greater photosynthetic capacity and/or efficiency may have been favourable and selected for. We used ca. 1000 exotic sorghum lines that have been introgressed with height and maturity quantitative trait loci (QTL) from a common parent (so-called sorghum conversion lines) to make the material easier to work with – and a nested association mapping population with around 1500 entries to mine this diversity for variation in alleles conferring photosynthetic capacity. In this paper, we report the use of near and remote-sensing technology, such as red (670nm), red- edge (720nm) and near infra-red (830nm) cameras mounted on unmanned aerial vehicles (UAVs) and hyperspectral sensors on a mobile phenotyping platform (GECKO) to be able to efficiently and effectively phenotype these populations for traits associated with photosynthetic capacity in replicated trials with thousands of field plots. To derive algorithms for the outputs from Lidar, sonar, thermal and hyperspectral sensors, we have collected “ground” data, such as chlorophyll content using handheld devices such as a SPAD chlorophyll and a fluorometer, measured plant height and leaf angle, as well as destructively measured leaf area index and biomass. This paper discusses the 1st season of results in developing field phenotyping methods to better characterise genetic variation for photosynthetic capacity