Thymic Development Research Articles

The Wiskott-Aldrich syndrome protein is required for positive selection during T-cell lineage differentiation.

The Wiskott-Aldrich syndrome (WAS) is an X-linked primary immune deficiency caused by a mutation in the WAS gene. This leads to altered or absent WAS protein (WASp) expression and function resulting in thrombocytopenia, eczema, recurrent infections, and autoimmunity. In T cells, WASp is required for immune synapse formation. Patients with WAS show reduced numbers of peripheral blood T lymphocytes and an altered T-cell receptor repertoire. In vitro, their peripheral T cells show decreased proliferation and cytokine production upon aCD3/aCD28 stimulation. It is unclear whether these T-cell defects are acquired during peripheral activation or are, in part, generated during thymic development. Here, we assessed the role of WASp during T-cell differentiation using artificial thymic organoid cultures and in the thymus of humanized mice. Although CRISPR/Cas9 WAS knockout hematopoietic stem and progenitor cells (HSPCs) rearranged the T-cell receptor and differentiated to T-cell receptor (TCR)+ CD4+ CD8+ double-positive (DP) cells similar to wild-type HSPCs, a partial defect in the generation of CD8 single-positive (SP) cells was observed, suggesting that WASp is involved in their positive selection. TCR repertoire analysis of the DP and CD8+ SP population, however, showed a polyclonal repertoire with no bias toward autoreactivity. To our knowledge, this is the first study of the role of WASp in human T-cell differentiation and on TCR repertoire generation.

Cytokine receptor γc effectuates the generation of proinflammatory innate CD8 T cells by non-classical MHC-I molecules

Innate CD8 T cells correspond to a population of terminally differentiated effector T cells that phenotypically appear as antigen-experienced memory cells and functionally resemble proinflammatory CD8 T cells, expressing copious amounts of IFNγ. Innate CD8 T cells, however, are distinct from conventional effector-memory CD8 T cells as they acquire functional maturity during their generation in the thymus. Understanding the molecular mechanisms that drive their thymic development and differentiation is an intensely studied subject in T cell immunity, and here we identified the cytokine receptor γc as a critical mediator of innate CD8 T cell generation that promotes their selection even in the absence of classical MHC-I molecules. Consequently, overexpression of γc resulted in a dramatic increase of innate CD8 T cells in KbDb-deficient mice. We mapped its underlying mechanism to the expansion of IL-4-producing invariant NKT cells, so that it is the increased availability of intrathymic IL-4 which augments the selection of innate CD8 T cells. Collectively, these results unravel the selection of innate CD8 T cells being mediated by non-classical MHC-I molecules and being modulated by the abundance of the γc cytokine, IL-4.

Changes in Thymic Size and Immunity Are Associated with Bronchopulmonary Dysplasia.

Preterm infants with bronchopulmonary dysplasia (BPD) are at increased risk for dysfunctional immune responses in the postnatal period. This study aimed to verify the hypothesis that thymic function is altered in infants with BPD and changes in the expression of thymic function-related genes affect thymic development. Included in the study were infants who had a gestational age ≤32 weeks and survived to a postmenstrual age of ≥36 weeks. The clinical features and thymic size were comparatively studied between infants with and without BPD. Thymic function and the expression of thymic function-related genes were determined in BPD infants at birth, week 2, and 4 of life. The thymic size was ultrasonographically assessed in terms of the thymic index (TI) and thymic weight index (TWI). T-cell receptor excision circles (TRECs) and gene expression were quantitatively determined by real-time quantitative reverse transcription polymerase chain reaction. Compared to non-BPD infants, their BPD counterparts had a shorter GA, lower birth weight, lower Apgar scores at birth, and were more likely to be of the male gender. BPD infants had an elevated incidence of respiratory distress syndrome and sepsis. TI was 1.73 ± 0.68 versus 2.87 ± 0.70 cm3 and TWI was 1.38 ± 0.45 versus 1.72 ± 0.28 cm3/kg in the BPD group versus the non-BPD group (p < 0.05). In BPD infants, no significant changes were observed in thymic size, lymphocyte counts, and TREC copy numbers at the first 2 weeks (p > 0.05), but they all exhibited a significant increase at week 4 (p < 0.05). BPD infants presented a trend toward increased expression of transforming growth factor-β1 and decreased expression of forkhead box protein 3 (Foxp3) from birth to week 4 (p < 0.05). Nonetheless, no significant difference was found in IL-2 or IL-7 expression at all time points (p > 0.05). For preterm infants with BPD, reduced thymic size at birth might be associated with impaired thymic function. Thymic function was developmentally regulated in the BPD process. · For preterm infants with BPD, reduced thymic size at birth might be associated with impaired thymic.. · BPD infants had an elevated incidence of respiratory distress syndrome and sepsis.. · Thymic function was developmentally regulated in the BPD process..

Influence of SLAM/SAP signaling on γδ T cell TCR signal strength during thymic development

Abstract Innate-like T cells are unusual T cells that are enriched in mucosal tissues, where they constitute a prominent source of pro-inflammatory cytokines like IL-17 and IFN-γ. During thymic development, mouse γδ T cells commit to either γδT1, γδT2, or γδT17 phenotypes through mechanisms that remain unclear. Recent observations from our laboratory have suggested a role for the SLAM/SAP signaling pathway in γδ T cell thymic developmental programming. Here, we investigated the influence of the SLAM/SAP signaling pathway on γδ TCR signal strength during thymic development. Using Nur77 GFPexpression as a readout of TCR signal strength, we observed significantly greater Nur77 GFPexpression in B6.Nur77 GFP.SAP −/−thymic γδ T cells compared their B6.Nur77 GFPcounterparts, suggesting that SAP inhibited TCR signal strength. Consistent with these findings, we observed significantly greater Erk phosphorylation in CD3-stimulated B6.SAP −/−thymic γδ T cells. In vitrostimulation of thymic γδ T cells with anti-TCRδ and anti-SLAM family receptors revealed that SLAMF6 co-stimulation resulted in decreased Erk phosphorylation, but increased Nur77 GFPexpression. Surprisingly, the effects of SLAMF6 co-stimulation on γδ TCR signaling were SAP-independent. Together, these data suggest an inhibitory role for SAP in γδ TCR signaling during thymic developmental programming.

Gads is differentially required for the thymic development of conventional and innate-like T cells

Abstract Thymocyte development is tightly regulated by TCR signaling. Gads bridges a TCR-inducible interaction between SLP-76 and LAT, two adaptors that are essential for T cell development. In contrast, Gads-deficient mice have moderately impaired thymic development and accumulate non-naive peripheral T cells of unclear origin. To illuminate the regulatory roles of Gads, we developed a model for tamoxifen-induced ablation of Gads (Gads iKO), accompanied by the expression of tdTomato. Using this model, we followed the fate of Gads iKO(Tom +) and Gads +(Tom −) thymocytes within the same mouse. Compared to Gads +(Tom −) DN thymocytes, Gads iKO(Tom +) DN thymocytes were less likely to undergo conventional β-selection; yet their ability to develop into γδ or NKT cells was not impaired. A key feature of thymocyte development is the TCR-induced upregulation of CD5, which occurs during β-selection and further increases upon positive selection. Nevertheless, most Gads iKODP thymocytes did not express CD5, nor did they increase calcium upon TCR ligation. These observations suggest that a TCR-independent, innate-like thymic developmental pathway may be unmasked in the absence of Gads. Gads iKOSP thymocytes were heterogeneous: some were CD5 −TCR lo, while others were CD5 +TCR hi. Among the CD5 +Gads iKOCD4 SP thymocytes, a large proportion exhibited innate-like characteristics such CD44 hiCD62L loand/or NK1.1 +. In contrast, peripheral Gads iKOT cells maintained a naive CD44 loCD69L hiphenotype for up to five weeks. Our results suggest that Gads is dispensable for peripheral quiescence, but regulates thymic development, by promoting conventional αβ T cell development, while suppressing innate-like developmental fates. Supported by a grant from the Israel Science Foundation, and by a short-term grant from the Rappaport Institute for Research in the Medical Sciences

DNA demethylation fine-tunes IL-2 production during thymic development and promotes Regulatory T cell differentiation

Abstract Regulatory T (T reg) cells developing in the thymus are essential to maintain tolerance and prevent fatal autoimmunity in mice and humans. Expression of the T reg lineage-defining transcription factor FoxP3, is critically dependent upon T cell receptor (TCR) and interleukin-2 (IL-2) signaling. Here, we report that ten-eleven translocation (Tet) enzymes, which are DNA demethylases, are required early during double positive (DP) thymic T cell differentiation and prior to the upregulation of FoxP3 in CD4 single-positive (SP) thymocytes, to promote Treg differentiation. We show that Tet enzymes selectively control the development of CD25 −FoxP3 loCD4SPTreg cell precursors and are critical for optimal TCR-dependent IL-2 production, which drive chromatin remodeling at the FoxP3 locus as well as other Treg-effector gene loci in an autocrine/paracrine manner. Together, our results demonstrate a novel role for DNA demethylation in regulating the TCR response and promoting Treg cell differentiation. These findings highlight a novel epigenetic pathway to promote the generation of endogenous Treg cells for mitigation of autoimmune responses.

Molecular circuitry of T-cell Development and Leukemogenesis.

Abstract T-cell Acute lymphoblastic leukemia (T-ALL) is an aggressive disease with only a 10% 5-year survival rate for patients over 60, due to genomic instability. We have shown that β-catenin and TCF-1 cooperate in DP thymocytes to promote genomic instability leading to lymphomagenesis. We have also established that TCF-1 and HEB cooperate in the DP stage. Now, we aim to determine the molecular underpinnings of T-ALL and thymic development, by elucidating the interplay of all three factors, β-catenin, TCF-1, and HEB. Aberrant activation of β-catenin promotes the development of Lymphoma/Leukemia equivalent to the human disease T-ALL and blocks thymocyte development in the early DP stage. Ablation of TCF-1 in thymocytes with activated β-catenin rescues from lymphomagenesis, but the developmental block persists. Antithetically, developmental progression is achieved only when HEB is conditionally knocked out. In an effort to explain this phenomenon, we found that genes associated with the transition of DP thymocytes from DPsmall to CD69+ are downregulated by activating β-catenin (e.g. Runx-3, Ccr-7, TOX-2, etc.) and revert upon deletion of HEB. This is associated with changes in the binding of TCF-1 to DNA. Genomic sites that acquire TCF-1 binding upon β-catenin activation forfeit this binding when HEB is deleted, while at the same time novel TCF-1 binding sites emerge. These new binding sites are significantly more enriched for the conserved TCF-1 motif than TCF-1-bound sites in WT thymocytes. This observation promotes the notion that HEB guides TCF-1 towards alternative binding sites, thus altering gene expression. These findings highlight the complex interactive relationship of TCF-1 and HEB in both normal development and disease. NIH/NIAID R01 AI147652-01A1

Neural crest-derived mesenchymal cells support thymic reconstitution after lethal irradiation.

Abstract The thymus is composed of thymocytes and stromal cells including thymic epithelial and mesenchymal cells. Thymic mesenchymal cells are originated from Neural Crest (NC) cells and the mesoderm. Although it is known that NC-derived (NCd) cells contribute to thymus organogenesis and thymus development, their specific role in T cell regeneration is unclear. To evaluate the regenerative ability of NCd mesenchymal cells in the thymus, we used lethally irradiated mice to examine the effect of ionizing irradiation (IR) on the thymus size, thymocytes and the thymic stromal cells (thymic epithelial cells (TECs) and thymic mesenchymal cells). Additionally, we ablated NC-derived mesenchymal cells via in vitro diphtheria toxin (DT) administration in double transgenic mice (Wnt1-Cre/+; Rosa YFP/DTRmice) that express NC-specific Cre and Cre-driven DT receptor (DTR) and transplanted the thymus depleted of NC-derived mesenchyme under the renal capsules of non-irradiated C57BL/6 (CD45.1) mice. IR reduced the size of the thymus, the absolute numbers and percentages of thymocytes, primarily (CD4 +CD8 +) T cells and TECs. Moreover, IR reduced the number of thymic mesenchymal cells but not that of NC-derived mesenchymal cells. NC-derived mesenchymal cells upregulated several hematopoietic factors such as Flt3l, Periostin, Scf, and Bmp4after irradiation and supported thymic reconstitution. Taken together, our findings indicate that NC-derived mesenchymal cells are not only radio-resistant, but also produce molecules that may support early T-cell development for thymic reconstitution after irradiation .

Generation of thymic epithelial progenitor cells from induced pluripotent stem cells obtained from patients with thymic defects

Abstract Thymic epithelial cells (TECs) play a critical role in T-cell development as they provide essential cues to hematopoietic progenitors for their proliferation and differentiation in the thymus. Patients with genetic mutations affecting TEC functionality present with reduced thymus development and decreased T-cell output in the periphery. We have previously reported that T-cell development is blocked in patients with hematopoietic-intrinsic genetic defects using an artificial thymic organoid system, but this model does not allow testing of TEC defects. To address this, we have generated multiple induced pluripotent stem cell (iPSC) lines from patients carrying mutations on genes involved in thymic stromal development and/or function, including 22q11.2del (DiGeorge syndrome), CHD7, FOXI3, PAX1, AIRE, EXTL3, and TP63. We aim to differentiate these iPS lines into TECs and assess whether these mutations alter TEC generation. We are currently testing previously published protocols. However, most of these protocols focused on generating TECs from embryonic stem cells and were not optimized for human iPSCs. To address this, we are comparing and combining different methods to achieve a high efficiency in inducing definitive endoderm (DE), ventral pharyngeal endoderm (VPE) and finally thymic epithelial progenitors (TEP). We have already successfully reached the DE stage, as gene expression analysis by qPCR shows upregulation of genes associated with the DE and downregulation of iPS genes. Once we successfully generate TECs, we plan to incorporate them into our artificial thymic organoid system to create a model that will be solely based on human cells, obtaining a more accurate in vitroreflection of human thymic T cell development. This work was supported by the Division of Intramural Research (DIR), NIAID, NIH

Thymic innate lymphoid cells promote thymocyte differentiation of transplanted hematopoietic progenitors in immunodeficient mice.

Abstract Patients with combined immunodeficiencies can be cured by intravenous transfer of allogeneic hematopoietic stem and progenitor cells (HSPC). However, complications such as an impaired and delayed T cell differentiation are unfortunately common, notably due to the defective thymic architecture in these patients and the requirement of HSPC homing to the thymus. To circumvent these problems, we have developed an innovative approach based on the direct targeting of HSPC into the thymus by intrathymic (IT) injection. Using ZAP70-deficient mice as a paradigm, we previously showed that IT injection of HSPC can support a long-term thymus-autonomous differentiation. Here, we show that the IT injection of WT HSPC results in a rapid engraftment and differentiation. Donor-derived thymocytes expand &amp;gt;100-fold, accounting for &amp;gt;13% of thymus cellularity by 3 weeks post IT transfer and importantly, engraftment occurs in the absence of cytoreductive conditioning. While mature CD4 thymocyte differentiation occurs in 3 weeks, the differentiation of mature Treg thymocytes requires 4 weeks. The kinetics of thymic Treg development parallels the generation of a thymic medulla, with the appearance of mature medullary thymic epithelial cells at 3–4 weeks post transplantation. Notably, the generation of the thymic medulla is associated with the differentiation of donor-derived RORγT+ innate lymphoid cells (ILC). While ILC are not required for physiological thymopoiesis, we find that they are critical for T cell differentiation in ZAP70-deficient mice presenting with an absence of the thymic medulla. These results may open new therapeutic avenues, promoting the differentiation of ILC via IT-mediated HSPC transfer, enhancing T cell differentiation. Supported by grants from ANR (CHIC) and AFM-Telethon

TBX1 copy number variant of unknown significance presenting as severe esophageal stricture and recurrent candidiasis

IntroductionTBX1 Is involved in pharyngeal pouch development affecting thymus, parathyroid, craniofacial, and cardiac outflow tract development. TBX1 deletions present with phenotype of Di George syndrome. We present the case of a patient with esophageal stricture and candidiasis showing a novel TBX1 gene triplication VUS. Case descriptionA 27-year-old male was hospitalized for hematemesis and progressive dysphagia. The physical exam was remarkable for short stature, underweight, dental hypoplasia, alopecia and occipital vitiligo. Calcium and lymphocyte numbers were normal. Severe esophageal strictures precluded upper endoscopy. He received IV fluconazole for two weeks to continue oral antifungal indefinitely. Since infancy he has had multiple candida infections in nails and oral mucosa requiring fluconazole, and medical history of asthma and atopic dermatitis. No history of cardiac abnormalities. At 14 years old he started with progressive dysphagia. Barium swallow and endoscopies showed severe acute and chronic esophagitis and thoracic esophageal strictures with severe stenosis. Patient's sister has history of candida infections, hypocalcemia due to hypoparathyroidism, and hypothyroidism. There is consanguinity among paternal grandparents. Invitae PID panel showed VUS with TBX1 gene triplication, not previously reported. Familial genetic testing was requested for her sister to support the diagnosis of DiGeorge Syndrome. DiscussionTBX1 gene deletions present a spectrum clinical phenotype including thymic hypoplasia, hypocalcemia, and congenital heart defects. TBX1 duplication and gain of function TBX1 heterozygous mutation led to protein dysfunction and a similar phenotype caused by loss-of-function mutations or deletions. TBX1 triplication could plausibly lead to dysfunctional protein expression, which requires confirmation. TBX1 is a negative regulator of thymic epithelial cell differentiation and proliferation, which could affect immune regulation and explain patient's chronic candida infections. Feeding difficulties and esophageal dysmotility have been reported in Di George syndrome. Sibling's hypocalcemia due to hypoparathyroidism could be explained by TBX1 dysfunction. APECED was considered in differential diagnosis due to chronic mucocutaneous candidiasis and sister's endocrinopathies, nevertheless, no AIRE or STAT1 mutations identified. Genetic analysis and familiar VUS have the potential to identify the cause of PIDs. TBX1 transcript and protein expression analysis will contribute to confirming the diagnostic impression.

Mechanisms regulating the loss of Tregs in HUPO mice that develop spontaneous inflammatory arthritis

T regulatory cells (Tregs) are a potential therapeutic target in many autoimmune diseases including rheumatoid arthritis (RA). The mechanisms responsible for the maintenance of Tregs in chronic inflammatory conditions such as RA are poorly understood. We employed our mouse model of RA in which, the following deletion of Flice-like inhibitory protein in CD11c+ cells, CD11c-FLIP-KO (HUPO) mice develop spontaneous, progressive, erosive arthritis, with reduced Tregs, and the adoptive transfer of Tregs ameliorates the arthritis. HUPO thymic Treg development was normal, but peripheral of Treg Foxp3 was diminished mediated by reduction of dendritic cells and interleukin-2 (IL-2). During chronic inflammatory arthritis Tregs fail to maintain Foxp3, leading to non-apoptotic cell death and conversion to CD4+CD25+Foxp3- cells. Treatment with IL-2 increased Tregs and ameliorated the arthritis. In summary, reduced dendritic cells and IL-2 in the milieu of chronic inflammation, contribute to Treg instability, promoting HUPO arthritis progression, and suggesting a therapeutic approach in RA.

Depletion of Ly6G-Expressing Neutrophilic Cells Leads to Altered Peripheral T-Cell Homeostasis and Thymic Development in Neonatal Mice.

Newborns and especially preterm infants are much more susceptible to infections than adults. Due to immature adaptive immunity, especially innate immune cells play an important role in a newborn's infection defense. Neonatal neutrophils exhibit profound differences in their functionality compared to neutrophils of adults. In particular, neonates possess a relevant population of suppressive neutrophils, which not only inhibit but also specifically modulate the function of T-cells. In this study, we investigated whether neonatal neutrophils are already involved in T-cell development in the thymus. For this purpose, we used a newly developed model of antibody-mediated immune cell depletion in which we administered a depleting antibody to pregnant and then lactating dams. Using this method, we were able to sufficiently deplete Ly6G-positive neutrophils in offspring. We demonstrated that the depletion of neutrophils in newborn mice resulted in altered peripheral T-cell homeostasis with a decreased CD4+/CD8+ T-cell ratio and decreased expression of CD62L. Neutrophil depletion even affected T-cell development in the thymus, with increased double positive thymocytes and a decreased CD4+/CD8+ single positive thymocyte ratio. Altogether, we demonstrated a previously unknown mechanism mediating neutrophils' immunomodulatory effects in newborns.

Dandelion uses the single-cell adaptive immune receptor repertoire to explore lymphocyte developmental origins.

Assessment of single-cell gene expression (single-cell RNA sequencing) and adaptive immune receptor (AIR) sequencing (scVDJ-seq) has been invaluable in studying lymphocyte biology. Here we introduce Dandelion, a computational pipeline for scVDJ-seq analysis. It enables the application of standard V(D)J analysis workflows to single-cell datasets, delivering improved V(D)J contig annotation and the identification of nonproductive and partially spliced contigs. We devised a strategy to create an AIR feature space that can be used for both differential V(D)J usage analysis and pseudotime trajectory inference. The application of Dandelion improved the alignment of human thymic development trajectories of double-positive T cells to mature single-positive CD4/CD8 T cells, generating predictions of factors regulating lineage commitment. Dandelion analysis of other cell compartments provided insights into the origins of human B1 cells and ILC/NK cell development, illustrating the power of our approach. Dandelion is available at https://www.github.com/zktuong/dandelion .

Development's Inaugural Outstanding Paper Prize.

Development's Inaugural Outstanding Paper Prize.

Development of the Thymus and Kidney and Effects of Resveratrol on Their Aging in a Short-LivedFish.

Annual fishes of the genus Nothobranchius have been widely used in cognitive, behavioral, and genetic studies, and have become an excellent animal model for studying aging. However, the development and degeneration of immune organs in annual fishes and the antagonistic effects of resveratrol remain unclear. In the present study, the development of thymus and kidney was investigated systematically using Nothobranchius guentheri from larvae, juveniles, and young and old fish with hematoxylin and eosin staining. We found that thymus primordium was observed first in the larvae at 2days after hatching (dah). After the lymphoid cells became evident at 5 dah, the thymus acquired an irregular shape at 7 dah. Then it formed a wedge shape at 15 dah. Thymus looked as homogeneous distribution of lymphocytes at 1month old, and it differentiated into cortex and medulla approximately in 2-month-old fish. Combined with TUNEL and senescence-associated β-galactosidase (SA-β-gal) staining, it showed the degeneration of the thymus appeared in 4-month-old fish. Kidney primordium appeared on 1 dah, and the glomerulus was visible at 7 dah. The nephrogenic activity was most apparent in 1-month-old fish. Alarge hematopoietic tissue was arranged in the renal interstitium in 2- and 3-month-old fish. In 6-month-old fish, the kidney structure became less dense. By 12months, the kidney exhibited the most pronounced histological characteristics of aging. Feeding resveratrol ameliorated renal fibrosis and SA-β-gal staining with age, increased SIRT1 and SIRT3 expression, and decreased the levels of NF-κB and inflammatory factors in thymus and kidney of the fish. We provided basic data for the development and degeneration of immune organs and resveratrol's anti-aging effects in short-lived fish.

A network map of cytoskeleton-associated protein 4 (CKAP4) mediated signaling pathway in cancer.

Cytoskeleton-associated protein 4 (CKAP4) is a non-glycosylated type II transmembrane protein that serves as a cell surface-activated receptor. It is expressed primarily in the plasma membranes of bladder epithelial cells, type II alveolar pneumocytes, and vascular smooth muscle cells. CKAP4 is involved in various biological activities including cell proliferation, cell migration, keratinocyte differentiation, glycogenesis, fibrosis, thymic development, cardiogenesis, neuronal apoptosis, and cancer. CKAP4 has been described as a pro-tumor molecule that regulates the progression of various cancers, including lung cancer, breast cancer, esophageal squamous cell carcinoma, hepatocellular carcinoma, cervical cancer, oral cancer, bladder cancer, cholangiocarcinoma, pancreatic cancer, myeloma, renal cell carcinoma, melanoma, squamous cell carcinoma, colorectal cancer, and osteosarcoma. CKAP4 and its isoform bind to DKK1 or DKK3 (Dickkopf proteins) or antiproliferative factor (APF) and regulates several downstream signaling cascades. The CKAP4 complex plays a crucial role in regulating the signaling pathways including PI3K/AKT and MAPK1/3. Recently, CKAP4 has been recognized as a potential target for cancer therapy. Due to its biomedical importance, we integrated a network map of CKAP4. The available literature on CKAP4 signaling was manually curated according to the NetPath annotation criteria. The consolidated pathway map comprises 41 activation/inhibition events, 21 catalysis events, 35 molecular associations, 134 gene regulation events, 83 types of protein expression, and six protein translocation events. CKAP4 signaling pathway map data is freely accessible through the WikiPathways Database ( https://www.wikipathways.org/index.php/Pathway:WP5322 ). Generation of CKAP4 signaling pathway map.

Immunotoxicity induced by triclocarban exposure in zebrafish triggering the risk of pancreatic cancer

Owing to frequent application as a broad-spectrum bactericide, triclocarban (TCC) exposure has raised great concern for aquatic organisms and human health. Herein, based on transcriptome sequencing data analysis of zebrafish, we confirmed that TCC induced oxidative stress and dysimmunity through transcriptional regulation of the related genes. With aid of the Cancer Genome Atlas (TCGA) assembler database, 52 common differentially expressed genes, whose functions were related to immunity, were screened out by virtue of the meta-analysis of pancreatic cancer sample data and differential transcription profiles from TCC-exposed larvae. Acute TCC exposure affected formation of the innate immune cells, delayed mature thymic T-cell development, reduced immunoglobulin M (IgM) levels and promoted excessive release of the pro-inflammatory factors (IL-6, IL-1β and tnfα). Under TCC exposure, the expressions of the genes associated with immune cell abundance in pancreatic cancer were significantly down-regulated, while the levels of ROS were prominently increased in concomitant with suppressed antioxidant activity. Moreover, a series of marker genes (pi3k, nrf2, keap1, ho-1 and nqo1) in the PI3K/Nrf2 antioxidant-stress pathway were abnormally expressed under TCC exposure. Interestingly, vitamin C decreased the malformation and increased the survival rate of 120-hpf larvae and effectively alleviated TCC-induced oxidative stress and immune responses. Overall, TCC exposure induced immunotoxicity and increased the risk of pancreatic cancer by inhibiting the antioxidant capacity of the PI3K/Nrf2 signal pathway. These observations enrich our in-depth understanding of the effects of TCC on early embryonic-larval development and immune damage in zebrafish.

Congenital Athymia: Unmet Needs and Practical Guidance.

Inborn errors of thymic stromal cell development and function which are associated with congenital athymia result in life-threatening immunodeficiency with susceptibility to infections and autoimmunity. Athymic patients can be treated by thymus transplantation using cultured donor thymus tissue. Outcomes in patients treated at Duke University Medical Center and Great Ormond Street Hospital (GOSH) over the past three decades have shown that sufficient T-cell immunity can be recovered to clear and prevent infections, but post-treatment autoimmune manifestations are relatively common. Whilst thymus transplantation offers the chance of long-term survival, significant challenges remain to optimise the outcomes for the patients. In this review, we will discuss unmet needs and offer practical guidance based on the experience of the European Thymus Transplantation programme at GOSH. Newborn screening (NBS) for severe combined immunodeficiency (SCID) and routine use of next-generation sequencing (NGS) platforms have improved early recognition of congenital athymia and increasing numbers of patients are being referred for thymus transplantation. Nevertheless, there remain delays in diagnosis, in particular when the cause is genetically undefined, and treatment accessibility needs to be improved. The majority of athymic patients have syndromic features with acute and chronic complex health issues, requiring life-long multidisciplinary and multicentre collaboration to optimise their medical and social care. Comprehensive follow up after thymus transplantation including monitoring of immunological results, management of co-morbidities and patient and family quality-of-life experience, is vital to understanding long-term outcomes for this rare cohort of patients. Alongside translational research into improving strategies for thymus replacement therapy, patient-focused clinical research will facilitate the design of strategies to improve the overall care for athymic patients.

Differences in Age-Related Changes in the Thymus in Rats Developmentally Exposed to Endocrine Disrupter Dichlorodiphenyltrichloroethane.

We studied features of age-related changes in the thymus of mature male Wistar rats developmentally exposed to the endocrine disruptor dichlorodiphenyltrichloroethane (DDT). The study was carried out at the stage of early thymus involution. Differences in the thymus morphology associated with imbalance of morphogenetic processes in the cortex and medulla were observed after puberty in rats developmentally exposed to DDT. Increased proliferation of thymocytes, higher content of lymphoblasts, and concomitant decrease in T-cell migration in comparison with the control were found. Our findings indicate lower functional maturity of the thymus and prolonged disorders in the program of postnatal thymus development induced by the endocrine disruptor DDT.