The C-type lectin receptor SIGNR3 binds to fungi present in commensal microbiota and influences immune regulation in experimental colitis

Inflammatory bowel disease is a condition of acute and chronic inflammation of the gut. An important factor contributing to pathogenesis is a dysregulated mucosal immunity against commensal bacteria and fungi. Host pattern- recognition receptors (PRRs) sense commensals in the gut and are involved in maintaining the balance between controlled responses to pathogens and overwhelming innate immune activation. C-type lectin receptors (CLRs) are PRRs recognizing glycan structures on pathogens and self-antigens. Here we examined the role of the murine CLR specific intracellular adhesion molecule-3 grabbing non-integrin homolog-related 3 (SIGNR3) in the recognition of commensals and its involvement in intestinal immunity. SIGNR3 is the closest murine homolog of the human dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) receptor recognizing similar carbohydrate ligands such as terminal fucose or high-mannose glycans. We discovered that SIGNR3 recognizes fungi present in the commensal microbiota. To analyze whether this interaction impacts the intestinal immunity against microbiota, the dextran sulfate sodium-induced colitis model was employed. SIGNR3(-/-) mice exhibited an increased weight loss associated with more severe colitis symptoms compared to wild-type control mice. The increased inflammation in SIGNR3(-/-) mice was accompanied by a higher level of TNF-α in colon. Our findings demonstrate for the first time that SIGNR3 recognizes intestinal fungi and has an immune regulatory role in colitis

Adaptive Movement Compensation for In Vivo Imaging of Fast Cellular Dynamics within a Moving Tissue

In vivo non-linear optical microscopy has been essential to advance our knowledge of how intact biological systems work. It has been particularly enabling to decipher fast spatiotemporal cellular dynamics in neural networks. The power of the technique stems from its optical sectioning capability that in turn also limits its application to essentially immobile tissue. Only tissue not affected by movement or in which movement can be physically constrained can be imaged fast enough to conduct functional studies at high temporal resolution. Here, we show dynamic two-photon Ca2+ imaging in the spinal cord of a living rat at millisecond time scale, free of motion artifacts using an optical stabilization system. We describe a fast, non-contact adaptive movement compensation approach, applicable to rough and weakly reflective surfaces, allowing real-time functional imaging from intrinsically moving tissue in live animals. The strategy involves enslaving the position of the microscope objective to that of the tissue surface in real-time through optical monitoring and a closed feedback loop. The performance of the system allows for efficient image locking even in conditions of random or irregular movements

Two-photon imaging of neural activity and structural plasticity in the rodent spinal cord

In my PhD thesis, I used two‐photon imaging to investigate neuronal circuits and glia cells in the spinal cord of living mice. To achieve this, a major effort first was to establish a mouse spinal cord preparation suitable for stable and long‐lasting imaging experiments. Without adequate stabilisation, the spinal cord was prone to large‐scale movement artefacts clearly hampering high‐resolution imaging in vivo. To overcome these limitations, I employed strategies to optimise the animals posture, namely rigid clamping of the vertebral column to isolate the spinal cord from breathing‐related movements. In addition, I developed strategies to dampen tissue movements remaining after posture optimisation. These improvements made it possible to image the structural plasticity of genetically labelled microglia cells with subcellular resolution for many hours in anesthetized mice. In a paradigm of focal spinal cord injury, microglia became rapidly activated and displayed high levels of filopodial motility clearly directed towards the injury site. In addition, I adapted Ca2+ indicator loading techniques to stain neuronal networks in the mouse superficial dorsal horn to visualize activity patterns of painprocessing neurons. Despite the heavily myelinated surrounding tissue, neuronal populations within the first two laminae could be visualized after Ca2+ indicator loading. The preparation was sufficiently stable to for the first time resolve fast, individual Ca2+ transients in the spinal cord of living rodents. In agreement with the role of dorsal horn circuits in nociceptive processing I found low rates of spontaneous activity but could reliably evoke increased activity levels by electrical stimulation of primary afferent fibres in situ. Specifically, also natural sensory stimulation applied to the paw elicited Ca2+ transients in a subset of dorsal horn neurons. In a parallel project, I collaborated with Klas Kullander’s group to investigate activity patterns of identified Renshaw cells during an in vitro model of locomotion. Using two‐photon Ca2+ imaging in the isolated neonatal mouse SC, we found that several subclasses of Renshaw cells are differentially engaged in ongoing locomotion. In addition, the activities of the different Renshaw cell populations were correlated with subgroups of simultaneously recorded motoneurons. Afferent inputs delivered during ongoing locomotion perturbed the locomotor rhythm and the nature of perturbations depended on stimulus timing during either the flexor‐ or extensor‐related cycle phase. On the local circuit level, we observed that correlations between specific Renshaw cells and motoneuron subpopulations were boosted by sensory input and that this effect also depended on stimulus timing. In a broader context, these results can be interpreted as reflections of synaptic strengthening of developing locomotor modules by sensory inputs

Exercise: What Does the Evidence Say About its Role in Prevention and Management of Lymphedema

Exercise is now considered safe for those with or at risk of developing lymphedema following cancer. However, how much exercise is enough, how much is too much and what type of exercise is best? This workshop will present the findings of a systematic literature review which was conducted to assess 1) the role of exercise in lymphedema prevention; 2) the acute and longer term effects of exercise training on lymphoedema; 3) summarise the strength of evidence for various types of exercise; and 4) summarise the evidence relating to the need to wear compression during exercise. National and international exercise guidelines will be presented and compared against the evidence presented. The objectives of this workshop include: 1. identifying why we should even consider exercise with respect to the prevention and/or treatment of lymphedema; 2. to describe the quality of the scientific evidence exploring the role of exercise in the prevention of lymphedema; 3. to provide an overview of the evidence regarding the role of exercise in the management of lymphedema; 4. to determine whether this evidence is dependent on exercise type; 5. to summarise the role of exercise for those with lymphedema with respect to health benefits; and 6. to translate how this evidence can be used in clinical practice

Histological analysis of colon sections from wild-type and DCIR^−/− mice.

<p>Paraffin sections of the colon from untreated or 3% DSS-treated wild-type and DCIR^−/− mice were prepared at day seven and were stained with hematoxylin and eosin (H&E) for histological evaluation in a blinded manner. (<b>A</b>) Representative images of paraffin-embedded sections of the rectal part of the colon are shown (40x magnification). Arrows indicate a severe ulcer in the colon from DCIR^−/− mice. Each colon was divided into three segments of identical length (oral, middle, rectal) which were separately analyzed. The degree of leukocyte infiltration (<b>B</b>) and mucosal erosion/ulceration (<b>C</b>) was graded from none (score 0) to mild (score 1), moderate (score 3), or severe (score 4). The scores for both, cell infiltration as well as mucosal ulceration in the rectal part of the colon from DCIR^−/− mice were significantly increased compared to wild-type mice. Data are expressed as mean + SEM (n = 5). The <i>p</i>-values were determined using Mann-Whitney’s U test (*<i>p</i><0.05, **<i>p</i><0.01). Significance is indicated by asterisks (*), ns = no significance.</p

Scoring for the histological evaluation of intestinal lesions.

<p>Scoring for the histological evaluation of intestinal lesions.</p

Local cytokine concentrations in the colon of wild-type, MCL^−/−, and DCIR^−/− mice.

<p>Colons from untreated wild-type mice or from wild-type and MCL^−/− mice (n = 6) (<b>A</b>), or wild-type and DCIR^−/− mice (n = 7 for wild-type and n = 8 for DCIR^−/− mice) (<b>B</b>) treated with 3% DSS for seven consecutive days were homogenized and used for cytokine determination by cytometric bead array. Data are expressed as mean + SEM. Significance is indicated by asterisks (*), ns = no significance.</p