Early-life inflammation primes a T helper 2 cell-fibroblast niche in skin.

Inflammation early in life can prime the local immune milieu of peripheral tissues, which can cause lasting changes in immunological tone that confer disease protection or susceptibility1. The cellular and molecular mechanisms that prompt changes in immune tone in many nonlymphoid tissues remain largely unknown. Here we find that time-limited neonatal inflammation induced by a transient reduction in neonatal regulatory T cells causes a dysregulation of subcutaneous tissue in mouse skin. This is accompanied by the selective accumulation of type 2 helper T (TH2) cells within a distinct microanatomical niche. TH2 cells are maintained into adulthood through interactions with a fibroblast population in skin fascia that we refer to as TH2-interacting fascial fibroblasts (TIFFs), which expand in response to TH2 cytokines to form subcutaneous fibrous bands. Activation of the TH2-TIFF niche due to neonatal inflammation primes the skin for altered reparative responses to wounding. Furthermore, we identify fibroblasts in healthy human skin that express the TIFF transcriptional signature and detect these cells at high levels in eosinophilic fasciitis, an orphan disease characterized by inflammation and fibrosis of the skin fascia. Taken together, these data define a previously unidentified TH2 cell niche in skin and functionally characterize a disease-associated fibroblast population. The results also suggest a mechanism of immunological priming whereby inflammation early in life creates networks between adaptive immune cells and stromal cells to establish an immunological set-point in tissues that is maintained throughout life.

Layilin Anchors Regulatory T Cells in Skin.

Regulatory T cells (Tregs) reside in nonlymphoid tissues where they carry out unique functions. The molecular mechanisms responsible for Treg accumulation and maintenance in these tissues are relatively unknown. Using an unbiased discovery approach, we identified LAYN (layilin), a C-type lectin-like receptor, to be preferentially and highly expressed on a subset of activated Tregs in healthy and diseased human skin. Expression of layilin on Tregs was induced by TCR-mediated activation in the presence of IL-2 or TGF-ß. Mice with a conditional deletion of layilin in Tregs had reduced accumulation of these cells in tumors. However, these animals somewhat paradoxically had enhanced immune regulation in the tumor microenvironment, resulting in increased tumor growth. Mechanistically, layilin expression on Tregs had a minimal effect on their activation and suppressive capacity in vitro. However, expression of this molecule resulted in a cumulative anchoring effect on Treg dynamic motility in vivo. Taken together, our results suggest a model whereby layilin facilitates Treg adhesion in skin and, in doing so, limits their suppressive capacity. These findings uncover a unique mechanism whereby reduced Treg motility acts to limit immune regulation in nonlymphoid organs and may help guide strategies to exploit this phenomenon for therapeutic benefit.

Corpus Callosum White Matter Diffusivity Reflects Cumulative Neurological Comorbidity in Tuberous Sclerosis Complex.

INTRODUCTION: Neurological manifestations in Tuberous Sclerosis Complex (TSC) are highly variable. Diffusion tensor imaging (DTI) may reflect the neurological disease burden. We analyzed the association of autism spectrum disorder (ASD), intellectual disability (ID) and epilepsy with callosal DTI metrics in subjects with and without TSC. METHODS: 186 children underwent 3T MRI DTI: 51 with TSC (19 with concurrent ASD), 46 with non-syndromic ASD and 89 healthy controls (HC). Subgroups were based on presence of TSC, ASD, ID, and epilepsy. Density-weighted DTI metrics obtained from tractography of the corpus callosum were fitted using a 2-parameter growth model. We estimated distributions using bootstrapping and calculated half-life and asymptote of the fitted curves. RESULTS: TSC was associated with a lower callosal fractional anisotropy (FA) than ASD, and ASD with a lower FA than HC. ID, epilepsy and ASD diagnosis were each associated with lower FA values, demonstrating additive effects. In TSC, the largest change in FA was related to a comorbid diagnosis of ASD. Mean diffusivity (MD) showed an inverse relationship to FA. Some subgroups were too small for reliable data fitting. CONCLUSIONS: Using a cross-disorder approach, this study demonstrates cumulative abnormality of callosal white matter diffusion with increasing neurological comorbidity.

Marine Bioinspired Underwater Contact Adhesion.

Marine mussels and barnacles are sessile biofouling organisms that adhere to a number of surfaces in wet environments and maintain remarkably strong bonds. Previous synthetic approaches to mimic biological wet adhesive properties have focused mainly on the catechol moiety, present in mussel foot proteins (mfps), and especially rich in the interfacial mfps, for example, mfp-3 and -5, found at the interface between the mussel plaque and substrate. Barnacles, however, do not use Dopa for their wet adhesion, but are instead rich in noncatecholic aromatic residues. Due to this anomaly, we were intrigued to study the initial contact adhesion properties of copolymerized acrylate films containing the key functionalities of barnacle cement proteins and interfacial mfps, for example, aromatic (catecholic or noncatecholic), cationic, anionic, and nonpolar residues. The initial wet contact adhesion of the copolymers was measured using a probe tack testing apparatus with a flat-punch contact geometry. The wet contact adhesion of an optimized, bioinspired copolymer film was ∼15.0 N/cm(2) in deionized water and ∼9.0 N/cm(2) in artificial seawater, up to 150 times greater than commercial pressure-sensitive adhesive (PSA) tapes (∼0.1 N/cm(2)). Furthermore, maximum wet contact adhesion was obtained at ∼pH 7, suggesting viability for biomedical applications.

Tertiary lymphoid structures sustain cutaneous B cell activity in hidradenitis suppurativa.

Hidradenitis suppurativa (HS) is a chronic skin condition affecting approximately 1% of the US population. HS skin lesions are highly inflammatory and characterized by a large immune infiltrate. While B cells and plasma cells comprise a major component of this immune milieu, the biology and the contribution of these cells in HS pathogenesis are unclear. We aimed to investigate the dynamics and microenvironmental interactions of B cells within cutaneous HS lesions. Combining histological analysis, single-cell RNA sequencing, and spatial transcriptomics profiling of HS lesions, we defined the tissue microenvironment relative to B cell activity within this disease. Our findings identified tertiary lymphoid structures (TLSs) within HS lesions and described organized interactions among T cells, B cells, antigen-presenting cells, and skin stroma. We found evidence that B cells within HS TLSs actively underwent maturation, including participation in germinal center reactions and class switch recombination. Moreover, skin stroma and accumulating T cells were primed to support the formation of TLSs and facilitate B cell recruitment during HS. Our data definitively demonstrated the presence of TLSs in lesional HS skin and point to ongoing cutaneous B cell maturation through class switch recombination and affinity maturation during disease progression in this inflamed nonlymphoid tissue.

Tertiary Lymphoid Structures Sustain Cutaneous B cell Activity in Hidradenitis Suppurativa.

Background: Hidradenitis suppurativa (HS) skin lesions are highly inflammatory and characterized by a large immune infiltrate. While B cells and plasma cells comprise a major component of this immune milieu the biology and contribution of these cells in HS pathogenesis is unclear. Objective: We aimed to investigate the dynamics and microenvironmental interactions of B cells within cutaneous HS lesions. Methods: We combined histological analysis, single-cell RNA-sequencing (scRNAseq), and spatial transcriptomic profiling of HS lesions to define the tissue microenvironment relative to B cell activity within this disease. Results: Our findings identify tertiary lymphoid structures (TLS) within HS lesions and describe organized interactions between T cells, B cells, antigen presenting cells and skin stroma. We find evidence that B cells within HS TLS actively undergo maturation, including participation in germinal center reactions and class switch recombination. Moreover, skin stroma and accumulating T cells are primed to support the formation of TLS and facilitate B cell recruitment during HS. Conclusion: Our data definitively demonstrate the presence of TLS in lesional HS skin and point to ongoing cutaneous B cell maturation through class switch recombination and affinity maturation during disease progression in this inflamed non-lymphoid tissue.

Triceps Rupture and Repair in a Healthy, Young Woman following Rock Climbing.

Triceps tendon rupture in females is rare. In this case report, we present a young adult female patient with a distal triceps tendon rupture from bouldering treated with open surgical repair technique using a modified bone tunnel and suture anchor fixation technique. The diagnosis and technique for repair and postoperative rehabilitation are described. A review of the current literature of biomechanical and clinical outcomes of various repair techniques is also presented.

Immunopathogenesis of hidradenitis suppurativa and response to anti-TNF-α therapy.

Hidradenitis suppurativa (HS) is a highly prevalent, morbid inflammatory skin disease with limited treatment options. The major cell types and inflammatory pathways in skin of patients with HS are poorly understood, and which patients will respond to TNF-α blockade is currently unknown. We discovered that clinically and histologically healthy appearing skin (i.e., nonlesional skin) is dysfunctional in patients with HS with a relative loss of immune regulatory pathways. HS skin lesions were characterized by quantitative and qualitative dysfunction of type 2 conventional dendritic cells, relatively reduced regulatory T cells, an influx of memory B cells, and a plasma cell/plasmablast infiltrate predominantly in end-stage fibrotic skin. At the molecular level, there was a relative bias toward the IL-1 pathway and type 1 T cell responses when compared with both healthy skin and psoriatic patient skin. Anti-TNF-α therapy markedly attenuated B cell activation with minimal effect on other inflammatory pathways. Finally, we identified an immune activation signature in skin before anti-TNF-α treatment that correlated with subsequent lack of response to this modality. Our results reveal the fundamental immunopathogenesis of HS and provide a molecular foundation for future studies focused on stratifying patients based on likelihood of clinical response to TNF-α blockade.

Developing Human Skin Contains Lymphocytes Demonstrating a Memory Signature.

Lymphocytes in barrier tissues play critical roles in host defense and homeostasis. These cells take up residence in tissues during defined developmental windows, when they may demonstrate distinct phenotypes and functions. Here, we utilized mass and flow cytometry to elucidate early features of human skin immunity. Although most conventional αß T (Tconv) cells in fetal skin have a naive, proliferative phenotype, a subset of CD4+ Tconv and CD8+ cells demonstrate memory-like features and a propensity for interferon (IFN)γ production. Skin regulatory T cells dynamically accumulate over the second trimester in temporal and regional association with hair follicle development. These fetal skin regulatory T cells (Tregs) demonstrate an effector memory phenotype while differing from their adult counterparts in expression of key effector molecules. Thus, we identify features of prenatal skin lymphocytes that may have key implications for understanding antigen and allergen encounters in utero and in infancy.

Longitudinal Effects of Everolimus on White Matter Diffusion in Tuberous Sclerosis Complex.

OBJECTIVE: We studied the longitudinal effects of everolimus, an inhibitor of the mammalian target of rapamycin (mTOR), on callosal white matter diffusion tensor imaging (DTI) in patients with tuberous sclerosis complex (TSC). METHODS: Serial imaging data spanning nine years were used from the open label, Phase I/II trial (NCT00411619) and open-ended extension phase of everolimus for the treatment of subependymal giant cell astrocytoma associated with TSC. From 28 patients treated with everolimus and 25 untreated control patients, 481 MRI scans were available. Rigorous quality control resulted in omission of all scans with diffusion weighted imaging data in less than 15 directions or more than eight artifacted volumes, and all postsurgical scans. We applied a linear mixed-effects model to the remaining 125 scans (17 treated, 24 controls) for longitudinal analysis of each DTI metric of manually drawn callosal regions of interest. RESULTS: On a population level, mTOR inhibition was associated with a decrease in mean diffusivity. In addition, in treated patients only, a decrease of radial diffusivity was observed; in untreated patients only, an increase of axial diffusivity was seen. In patients below age 10, effect-sizes were consistently greater, and longer treatment was associated with greater rate of diffusion change. There was no correlation between DTI metrics and reduction of subependymal giant cell astrocytoma volume, or everolimus serum levels. CONCLUSIONS: Effects from mTOR overactivity on white matter microstructural integrity in TSC were modified through pharmacologic inhibition of mTOR. These changes sustained over time, were greater with longer treatment and in younger patients during a time of rapid white matter maturation.

Reproducibility of Structural and Diffusion Tensor Imaging in the TACERN Multi-Center Study.

BACKGROUND: Multi-site MRI studies are often necessary for recruiting sufficiently sized samples when studying rare conditions. However, they require pooling data from multiple scanners into a single data set, and therefore it is critical to evaluate the variability of quantitative MRI measures within and across scanners used in multi-site studies. The aim of this study was to evaluate the reproducibility of structural and diffusion weighted (DW) MRI measurements acquired on seven scanners at five medical centers as part of the Tuberous Sclerosis Complex Autism Center of Excellence Research Network (TACERN) multisite study. METHODS: The American College of Radiology (ACR) phantom was imaged monthly to measure reproducibility of signal intensity and uniformity within and across seven 3T scanners from General Electric, Philips, and Siemens vendors. One healthy adult male volunteer was imaged repeatedly on all seven scanners under the TACERN structural and DW protocol (5 b = 0 s/mm2 and 30 b = 1000 s/mm2) over a period of 5 years (age 22-27 years). Reproducibility of inter- and intra-scanner brain segmentation volumes and diffusion tensor imaging metrics fractional anisotropy (FA) and mean diffusivity (MD) within white matter regions was quantified with coefficient of variation. RESULTS: The American College of Radiology Phantom signal intensity and uniformity were similar across scanners and changed little over time, with a mean intra-scanner coefficient of variation of 3.6 and 1.8%, respectively. The mean inter- and intra-scanner coefficients of variation of brain structure volumes derived from T1-weighted (T1w) images of the human phantom were 3.3 and 1.1%, respectively. The mean inter- and intra-scanner coefficients of variation of FA in white matter regions were 4.5 and 2.5%, while the mean inter- and intra-scanner coefficients of variation of MD in white matter regions were 5.4 and 1.5%. CONCLUSION: Our results suggest that volumetric and diffusion tensor imaging (DTI) measurements are highly reproducible between and within scanners and provide typical variation amplitudes that can be used as references to interpret future findings in the TACERN network.

Regulatory T cells use arginase 2 to enhance their metabolic fitness in tissues.

Distinct subsets of Tregs reside in nonlymphoid tissues where they mediate unique functions. To interrogate the biology of tissue Tregs in human health and disease, we phenotypically and functionally compared healthy skin Tregs with those in peripheral blood, inflamed psoriatic skin, and metastatic melanoma. The mitochondrial enzyme, arginase 2 (ARG2), was preferentially expressed in Tregs in healthy skin, increased in Tregs in metastatic melanoma, and reduced in Tregs from psoriatic skin. ARG2 enhanced Treg suppressive capacity in vitro and conferred a selective advantage for accumulation in inflamed tissues in vivo. CRISPR-mediated deletion of this gene in primary human Tregs was sufficient to skew away from a tissue Treg transcriptional signature. Notably, the inhibition of ARG2 increased mTOR signaling, whereas the overexpression of this enzyme suppressed it. Taken together, our results suggest that Tregs express ARG2 in human tissues to both regulate inflammation and enhance their metabolic fitness.

A normative spatiotemporal MRI atlas of the fetal brain for automatic segmentation and analysis of early brain growth.

Longitudinal characterization of early brain growth in-utero has been limited by a number of challenges in fetal imaging, the rapid change in size, shape and volume of the developing brain, and the consequent lack of suitable algorithms for fetal brain image analysis. There is a need for an improved digital brain atlas of the spatiotemporal maturation of the fetal brain extending over the key developmental periods. We have developed an algorithm for construction of an unbiased four-dimensional atlas of the developing fetal brain by integrating symmetric diffeomorphic deformable registration in space with kernel regression in age. We applied this new algorithm to construct a spatiotemporal atlas from MRI of 81 normal fetuses scanned between 19 and 39 weeks of gestation and labeled the structures of the developing brain. We evaluated the use of this atlas and additional individual fetal brain MRI atlases for completely automatic multi-atlas segmentation of fetal brain MRI. The atlas is available online as a reference for anatomy and for registration and segmentation, to aid in connectivity analysis, and for groupwise and longitudinal analysis of early brain growth.

3D Super-Resolution Motion-Corrected MRI: Validation of Fetal Posterior Fossa Measurements.

PURPOSE: Current diagnosis of fetal posterior fossa anomalies by sonography and conventional MRI is limited by fetal position, motion, and by two-dimensional (2D), rather than three-dimensional (3D), representation. In this study, we aimed to validate the use of a novel magnetic resonance imaging (MRI) technique, 3D super-resolution motion-corrected MRI, to image the fetal posterior fossa. METHODS: From a database of pregnant women who received fetal MRIs at our institution, images of 49 normal fetal brains were reconstructed. Six measurements of the cerebellum, vermis, and pons were obtained for all cases on 2D conventional and 3D reconstructed MRI, and the agreement between the two methods was determined using concordance correlation coefficients. Concordance of axial and coronal measurements of the transcerebellar diameter was also assessed within each method. RESULTS: Between the two methods, the concordance of measurements was high for all six structures (P < .001), and was highest for larger structures such as the transcerebellar diameter. Within each method, agreement of axial and coronal measurements of the transcerebellar diameter was superior in 3D reconstructed MRI compared to 2D conventional MRI (P < .001). CONCLUSIONS: This comparison study validates the use of 3D super-resolution motion-corrected MRI for imaging the fetal posterior fossa, as this technique results in linear measurements that have high concordance with 2D conventional MRI measurements. Lengths of the transcerebellar diameter measured within a 3D reconstruction are more concordant between imaging planes, as they correct for fetal motion and orthogonal slice acquisition. This technique will facilitate further study of fetal abnormalities of the posterior fossa.

Construction of a deformable spatiotemporal MRI atlas of the fetal brain: evaluation of similarity metrics and deformation models.

The development and identification of best methods in fetal brain MRI analysis is crucial as we expect an outburst of studies on groupwise and longitudinal analysis of early brain development in the upcoming years. To address this critical need, in this paper, we have developed a mathematical framework for the construction of an unbiased deformable spatiotemporal atlas of the fetal brain MRI and compared it to alternative configurations in terms of similarity metrics and deformation models. Our contributions are twofold: first we suggest a novel approach to fetal brain spatiotemporal atlas construction that shows high capability in capturing anatomic variation between subjects; and second, within our atlas construction framework we evaluate and compare a set of plausible configurations for inter-subject fetal brain MRI registration and identify the most accurate approach that can potentially lead to most accurate results in population atlas construction, atlas-based segmentation, and group analysis. Our evaluation results indicate that symmetric diffeomorphic deformable registration with cross correlation similarity metric outperforms other configurations in this application and results in sharp unbiased atlases that can be used in fetal brain MRI analysis.

Current flexor and extensor tendon motion regimens: a summary.

This article summarizes select multinational early motion protocols. Included are flexor and extensor protocols for digital tendon repair in many forms. Custom orthosis design, exercise regimens, and advanced techniques are examples of what to expect. The goal of the article is to expose the reader to new ideas, educate regarding advanced techniques in tendon rehabilitation, and stimulate independent study to further the reader's skill set.