Thymic Involution Research Articles

Thymic Epithelial Cells Contribute to Thymopoiesis and T Cell Development.

The thymus is the primary lymphoid organ responsible for the generation and maturation of T cells. Thymic epithelial cells (TECs) account for the majority of thymic stromal components. They are further divided into cortical and medullary TECs based on their localization within the thymus and are involved in positive and negative selection, respectively. Establishment of self-tolerance in the thymus depends on promiscuous gene expression (pGE) of tissue-restricted antigens (TRAs) by TECs. Such pGE is co-controlled by the autoimmune regulator (Aire) and forebrain embryonic zinc fingerlike protein 2 (Fezf2). Over the past two decades, research has found that TECs contribute greatly to thymopoiesis and T cell development. In turn, signals from T cells regulate the differentiation and maturation of TECs. Several signaling pathways essential for the development and maturation of TECs have been discovered. New technology and animal models have provided important observations on TEC differentiation, development, and thymopoiesis. In this review, we will discuss recent advances in classification, development, and maintenance of TECs and mechanisms that control TEC functions during thymic involution and central tolerance.

Thymus Involution and Intravenous Drug Abuse.

Thymus glands from 283 autopsy cases were sampled and evaluated with histochemical and immunohistochemical methods. A subpopulation of 41 intravenous drug addicts were compared with age-matched control cases.It was found that an accelerated involution of the thymus occurred in the 20- to 25-year interval and thereafter with a steady pace of 5% per year. Also the size of Hassall bodies declined successively.In drug addicts, an increased dystrophic calcification of the Hassall bodies and a significant difference in thymus size (atrophy) compared with controls were seen. Moreover, a difference was seen in the relative numbers of CD4 and CD8 lymphocytes where CD4+ cells were reduced in drug addicts.It is hypothesized that signs of hepatitis C virus infection that was found in the majority of drug addicts and the reduced number of functionally intact Hassall corpuscles could explain the reduction of CD4+ lymphocytes and thymic hypotrophy in this population.

Impaired histomorphology might provoke cell cycle regulators alteration in thymus of children with various congenital heart defects

Thymus, as a primary site of appropriate adaptive immunity formation, is an essential organ in face of a self-tolerance as well as a potential menace from impairment of body integrity. Due to vital selection processes during differentiation and maturation of T lymphocytes, control over cell survival and programmed cell death must be orchestrated in detail. Indeed, thymus is highly sensitive to wide spectrum of stressors that initiate acute structural changes. Hypoxia, one of the most common complications in congenital heart defects (CHDs) patients, provokes stress-induced thymus involution. Disrupted embryolonic development of thymus in association with congenital heart defects, may negatively affect physiological immune mechanisms. We propose that detailed analysis of thymic morphology could critically contribute to unveil the pathophysiology of diseases associated with disrupted adaptive immunity in children with heterogeneous congenital heart diseases.

Qualitative Changes in Cortical Thymic Epithelial Cells Drive Postpartum Thymic Regeneration.

During gestation, sex hormones cause a significant thymic involution which enhances fertility. This thymic involution is rapidly corrected following parturition. As thymic epithelial cells (TECs) are responsible for the regulation of thymopoiesis, we analyzed the sequential phenotypic and transcriptomic changes in TECs during the postpartum period in order to identify mechanisms triggering postpartum thymic regeneration. In particular, we performed flow cytometry analyses and deep RNA-sequencing on purified TEC subsets at several time points before and after parturition. We report that pregnancy-induced involution is not caused by loss of TECs since their number does not change during or after pregnancy. However, during pregnancy, we observed a significant depletion of all thymocyte subsets downstream of the double-negative 1 (DN1) differentiation stage. Variations in thymocyte numbers correlated with conspicuous changes in the transcriptome of cortical TECs (cTECs). The transcriptomic changes affected predominantly cTEC expression of Foxn1, its targets and several genes that are essential for thymopoiesis. By contrast, medullary TECs (mTECs) showed very little transcriptomic changes in the early postpartum regenerative phase, but seemed to respond to the expansion of single-positive (SP) thymocytes in the late phase of regeneration. Together, these results show that postpartum thymic regeneration is orchestrated by variations in expression of a well-defined subset of cTEC genes, that occur very early after parturition.

Efficient generation of thymic epithelium from induced pluripotent stem cells that prolongs allograft survival

The thymus plays a significant role in establishing immunological self-tolerance. Previous studies have revealed that host immune reaction to allogeneic transplants could be regulated by thymus transplantation. However, physiological thymus involution hinders the clinical application of these insights. Here, we report an efficient generation of thymic epithelial-like tissue derived from induced pluripotent stem cells (iPSCs) and its potential to regulate immune reaction in allogeneic transplantation. We established an iPSC line which constitutively expresses mouse Foxn1 gene and examined the effect of its expression during in vitro differentiation of thymic epithelial cells (TECs). We found that Foxn1 expression enhances the differentiation induction of cells expressing TEC-related cell surface molecules along with upregulation of endogenous Foxn1. iPSC-derived TECs (iPSC-TECs) generated T cells in nude recipient mice after renal subcapsular transplantation. Moreover, iPSC-TEC transplantation to immuno-competent recipients significantly prolonged the survival of allogeneic skin. Our study provides a novel concept for allogeneic transplantation in the setting of regenerative medicine.

CD147 deficiency in T cells prevents thymic involution by inhibiting the EMT process in TECs in the presence of TGF\u03b2

Thymic involution during aging is a major cause of decreased T-cell production and reduced immunity. Here, we show that the loss of CD147 on T cells prevents thymic senescence, resulting in slowed shrinkage of the thymus with age and increased production of naive T cells. This phenotype is the result of slowing of the epithelial–mesenchymal transition (EMT) process in thymic epithelial cells (TECs), which eventually leads to reduced adipocyte accumulation. In an in vitro coculture system, we found that TGFβ is an important factor in the EMT process in TECs and that it can reduce the expression of E-cadherin through p-Smad2/FoxC2 signaling. Moreover, CD147 on T cells can accelerate the decline in E-cadherin expression by interacting with Annexin A2 on TECs. In the presence of TGFβ, Annexin A2 and E-cadherin colocalize on TECs. However, CD147 on T cells competitively binds to Annexin A2 on TECs, leading to the isolation of E-cadherin. Then, the isolated E-cadherin is easily phosphorylated by phosphorylated Src kinase, the phosphorylation of which was induced by TGFβ, and finally, p-E-cadherin is degraded. Thus, in the thymus, the interaction between T cells and TECs contributes to thymic involution with age. In this study, we illuminate the mechanism underlying the triggering of the EMT process in TECs and show that inhibiting TGFβ and/or CD147 may serve as a strategy to hinder age-related thymic involution.

Tyrosine phosphorylation related to thymic involution induced by diet restriction in comparison with aging

Tyrosine phosphorylation related to thymic involution induced by diet restriction in comparison with aging

Mechanisms of hormonal control of thymic differentiation process in the aspect of pregnancy

The effect of hormones (chorionic gonadotropin, estriol, leptin, ghrelin, kisspeptin) in the regulation of cell differentiation in the thymus was studied, in concentrations being comparable with the content in peripheral blood during pregnancy. It was established that the studied hormones regulate the functional activity of myeloid and plasmacytoid thymic dendritic cells in different directions, thus mediating the regulatory effects on the differentiation of thymocytes in contact with them. Hormones modulate the expression of the co-stimulatory activation and inhibitory molecules on myeloid and plasmacytoid thymic dendritic cells, as well as the activity of the enzyme indolamine-2,3-dioxigenase in general, increasing the tolerogenic potential of thymus dendritic cells. Hormone-influenced myeloid and plasmocytoid dendritic cells of the thymus have opposite effects on the formation of natural regulatory subpopulations of thymocytes (iNKT, nTreg, Th17), contributing to the successful development of physiological pregnancy. The effects of the studied hormones on the differentiation of αβ and δT cells in the thymus are mediated by the influence of hormones on both types of thymus dendritic cells, which complements the understanding of the regulatory mechanisms of steroid-induced thymus involution during pregnancy. Thus, the hormones produced by the placenta during pregnancy regulate the maturation and functional activity of thymus dendritic cells, modulating their ability to influence the differentiation of regulatory and effector populations of thymocytes. The obtained results reveal new mechanisms of hormonal regulation of the thymic differentiation of cells of the immune system which can be realized at different periods of pregnancy.

Idelalisib induces apoptosis in the lymphoid tissues and impairs lung function in mice

Idelalisib, an inhibitor of the phosphatidylinositol-3-kinase p110δ subunit (PI3Kδ), is approved for treating lymphoid malignancy. The drug is associated with hematopoietic and pulmonary toxicities, which limit its clinical use. However, the toxicity mechanisms are not completely elucidated. In this study, mice were intraperitoneally injected with idelalisib (40 or 80 µg/g) or dimethyl sulfoxide for five days every week for up to four weeks to evaluate the changes in the thymus, spleen, and pulmonary functions. Idelalisib treatment induced thymic involution, decreased CD4+/CD8+ T-cell population, and increased CD4-/CD8- T-cell population. In the spleen, idelalisib dose dependently decreased the lymphocyte viability and cell count. Idelalisib-treated mice exhibited enhanced cleaved caspase-3 expression in the thymus, spleen, and lung tissues. Idelalisib augmented thoracic and airway resistance and decreased thoracic compliance. Thus, PI3Kδ has physiological roles in T-cell development and airway function. Monitoring drug toxicity is important for developing follow-up compounds that target PI3Kδ signalling.

Gallic acid attenuates thymic involution in the d-galactose induced accelerated aging mice.

Senescence is an inevitable and complicated phenomenon. Age-associated thymic involution increases the risk of infectious diseases, which results in the immunosenescence and leads to a poor immune function. d-galactose (d-gal) can cause damages that resemble accelerated aging in mice. Gallic acid (GA), as one of the natural phenolic compounds, has been demonstrated to act in antioxidant and anti-tumor effects. In this study, we explored the effects of GA in preventing the age-related thymic involution and the alterations of the forkhead box protein N1 (FoxN1) in d-gal induced accelerated aging mice. The accelerated aging mice model was established by intraperitoneal injection d-gal for eight weeks and given GA with 200, 250, 500 mg/kg body weight per day, respectively, for six weeks. It showed that the d-gal-treated mice developed structural changes in the thymi compared to normal control mice. With supplement of GA, the mice restored the normal thymic anatomy, including the thickening cortex compartment and clearer cortico-medullary junction. The d-gal-treated mice showed a severe reduction in the number of thymocytes, GA mice also displayed the increased numbers of CD4 + T cells through flow cytometric analysis. GA treatment increased the proliferative cells by BrdU incorporation assay and reduced the numbers of apoptotic cells with FITC-12-dUTP labeling (TUNEL). The expression of FoxN1 was also found increased in GA treated mice by immunohistochemistry and quantitative reverse transcriptase PCR (qRT-PCR). Taken together, our results suggested that the administration of GA opposed the involution of thymus via stimulation of FoxN1 expression and proliferation of cells in a dose-dependent manner.

Development of the First Transgenic Animal Model for IRF4-Induced Lymphoid Malignancy

Introduction The transcription factor IRF4, a member of Interferon Regulatory Factor (IRF) family, is a critical regulator for the production of functional B and T lymphocytes. The dysregulation of IRF4 expression has been frequently implicated in various mature B- and T-lymphoid malignancies such as multiple myeloma and peripheral T-cell lymphomas in which IRF4 acts as an oncogene. However, in vivo model systems to investigate the oncogenic property of IRF4 has not been established. One of common downstream targets of IRF4 across different cancers is the oncogene, MYC, which promotes cell proliferation. Other downstream targets or collaborating factors of IRF4 in these malignancies have not been fully elucidated. Here, we established the first transgenic animal model for IRF4-induced lymphoma, which displays multiple spectrum of tumors providing an in vivo platform to study IRF4 oncogenicity. Methods and Results To identify the specific lineages and stages of the hematopoietic cells that can be transformed by IRF4, we utilized the zebrafish lck promoter, which is active both in T- and B-lymphocytes. We overexpressed human IRF4 gene in zebrafish under this promoter along with a fluorescent marker gene. We confirmed successful expression of both IRF4 and marker genes in the lymphocyte population. Strikingly, multiple F0 transgenic zebrafish showed an expansion of fluorescent signals arising from the thymus by 5 months, while control fish showed thymic involution after 4 months. Approximately 20% of F1 animals developed lymphoma within 5 months and progressed to leukemia by 8 months. Histopathological examination revealed massive infiltration of abnormal lymphocytes into skin, spinal cord, muscles, and liver, which resembles clinical and pathological features observed in several types of human mature T-cell neoplasms. Interestingly, the tumor onset and progression were significantly accelerated when crossed with p53e7/e7-mutant fish, which possesses transactivation-dead p53 variant. This reveals the synergy between IRF4 expression and p53 loss of function, which have also been observed in several types of human lymphomas. Notably, analysis of gene expression profiles using the single-cell RNA-sequencing platform revealed a simultaneous development of both B- and T-cell tumors, which consist of multiple clones at the early stage of tumorigenesis. T-cell-derived tumors became dominant at the late stage of tumorigenesis. Importantly, the expressions of mycb, the zebrafish orthologue of human MYC, as well as of other lymphoid transcription factors were highly upregulated in those tumors in parallel with IRF4 expression. Conclusion Our study demonstrated that IRF4 serves as a driver oncogene in the development of T- and B-cell malignancies. IRF4 accelerates the tumor progression by taking advantage of the impaired function of p53, as demonstrated by massive infiltration into distal organs recapitulating human lymphomas. Taken together, our zebrafish IRF4 model provides a very powerful platform to investigate the plausible mechanisms and pathways through which IRF4 exert its oncogenic property in lymphomagenesis. Disclosures Iida: Teijin Pharma: Research Funding; Astellas: Research Funding; Gilead: Research Funding; Sanofi: Research Funding; MSD: Research Funding; Abbvie: Research Funding; Kyowa Kirin: Research Funding; Chugai: Research Funding; Novartis: Honoraria, Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; Daichi Sankyo: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Janssen: Honoraria, Research Funding.

Towards Understanding & Uncovering New Key Players in T-Cell Development upon Aging

Aging-associated immune remodeling (AAIR) leads to an impaired ability to respond to vaccination and combat infections, and is due to many factors acting in concert. Several studies have linked the T-cell decline that occurs with age to thymic involution. However, there is novel and mounting evidence that also aged lymphoid-primed multipotent progenitors (LMPPs) are immune system intrinsic players in AAIR. However, very little is known on molecular and cellular mechanisms by which aging LMPPs could drive this AAIR phenomenon. Deciphering the underlying mechanisms is of crucial importance for developing new therapies to attenuate AAIR. Here, we present new data demonstrating the dysregulated pathways associated with aged LMPPs and the cellular changes in early thymic differentiation events in driving AAIR. To assess the T-lineage potential of aged LMPPs, we performed single cells ex-vivo OP9D assays using LMPPs (Lin-cKit+Sca1+CD34-Flt3hi) from aged (18-20 month-old) and young (8-10 week-old) C57BL/6 animals as controls. The frequencies of T-cell lineage potential in aged LMPPs and young LMPPs at the single cell level were very similar. This result was also validated in vivo by transplantation assays where 5000 aged or young LMPPs were injected into sub-lethally irradiated young recipients followed by T-cell lineage (CD4+ & CD8+) analysis in the peripheral blood (PB) at 4 weeks post transplantation (Mean; Y:12,75 vs A:16:23 % of total, p=0.46). However, aged LMPPs were associated with a dramatic disadvantage of PB T-cells at 4 weeks post injections (Mean; Y:9 vs A:2.3 % of total, p<0.0001) and in the development of all thymic stages of thymocytes, from early double negative stage CD4-CD8-(DN1) (Mean; Y:30 vs A:8 % of parent, p<0.0001) to double positive stage CD4+CD8+(DP) (Mean; Y:53 vs A:15 % of parent, p<0.0001), as well as single positive (SP) CD4+(Mean; Y:54 vs A:13 % of parent, p<0.0001) and CD8+(Mean; Y:45 vs A:10 % of parent, p<0.0001) thymocytes when intravenously transplanted in combination with 1:1 ratio of young LMPPs into young recipients. To overcome a potential homing to the thymus bias of aged LMPPs in competitive transplants, we performed intra-thymic injections of young and aged LMPPs with identical ratios into sub-lethally irradiated young recipients. The analysis of PB at 4 weeks post injections show a dramatic reduction of PB T-cells derived from aged LMPPs in comparison with young LMPPs (Mean; Y:14.8 vs A:8 % of total, p<0.0001). There was primarily a strong disadvantage towards generating DP stage (Mean; Y:46 vs A:28 % of parent, p<0.0001), suggesting that the intra-thymic injections indeed alleviated the dramatic decrease in the early thymocyte stage DN1 (Mean; Y:31 vs A:22 % of parent, p<0.05). This suggests that aged LMPPs confer a T-cell differentiation and maybe an additional homing to the thymus defect. We also performed RNA-Seq analyses on LMPPs from young and aged mice. Unsupervised hierarchical clustering of differentially expressed genes between young and aged LMPPs highlighted a clear dysregulation of only a few pathways that are involved in T-cell development such as Notch signaling. We next correlated our RNA-Seq data with other immunological signatures in attempt to look for more T-cell specific key factors that are differentially expressed between young and aged LMPPs. Importantly, the results show that the data from our RNA-Seq correlated with more than 400 immunological signatures among which 25 were most highly correlated. Interestingly, this correlation has allowed us to curate a list of the top 30 differentially expressed genes between young and aged LMPPs including T-cell specific transcription factors such as Satb1 and Foxo1. Altogether, our findings reveal that the T-cell immune decline that occurs with age is already imprinted in LMPPs within the bone marrow and translates into a dysregulation of signaling pathways that are directly related to T-cell development. Targeting these pathways could open up new perspectives in attenuating AAIR. Disclosures No relevant conflicts of interest to declare.

SCIDOT-34. BRAIN INJURY SIGNALS SYSTEMIC IMMUNOSUPPRESSION THROUGH THYMIC INVOLUTION

Abstract Systemic immunosuppression following neurological insults including stroke, traumatic brain injury, and glioblastoma (GBM) causes mortality and leads to failure of immune-modulating therapies. Exact immunological nature and the underlying mechanisms of this immunosuppression are unknown. Our goal was to define effects of neurological insults given exclusively to the brain on the thymus. The thymus is the primary immune organ responsible for T-cell development and maintenance both in children and in adults. We evaluated the brain-thymus communication using the following neurological insults: physical injury, CNS viral infection, sterile injury, tumor implantation, and seizures. All insults resulted in significant thymic involution that was reversible upon clearance of the insult. Thymic involution did not occur following similar peripheral insults. We next demonstrated that the GL261 model of GBM recapitulates hallmark features of peripheral immunosuppression observed in GBM patients including low CD4 T-cell counts. Thus, we aimed to further study the immunosuppression affecting the thymus in this clinically relevant model. Principle component analysis following RNA-sequencing of thymi from naïve and glioma-bearing mice revealed unbiased separation of the groups suggesting that the thymus is directly affected by a brain tumor. To determine the extent to which thymic involution was caused by a soluble factor we employed parabiosis. We demonstrated that thymic involution was transferable from glioma-bearing to non-tumor-bearing parabionts. Similarly, serum taken from GL261 glioma-bearing mice potently inhibited proliferation of T-cells in vitro. Together our data demonstrate that CNS-specific insults, regardless of nature, cause immunosuppression by prompting thymic involution through circulating factors. This accounts at least partially for immune deficiencies observed following neurological injuries. Identification of this suppressive factor is crucial in designing future therapeutics for GBM patients, and patients with other acute and chronic neurological trauma.

Cell generation dynamics underlying naive T-cell homeostasis in adult humans.

Thymic involution and proliferation of naive T cells both contribute to shaping the naive T-cell repertoire as humans age, but a clear understanding of the roles of each throughout a human life span has been difficult to determine. By measuring nuclear bomb test–derived 14C in genomic DNA, we determined the turnover rates of CD4+ and CD8+ naive T-cell populations and defined their dynamics in healthy individuals ranging from 20 to 65 years of age. We demonstrate that naive T-cell generation decreases with age because of a combination of declining peripheral division and thymic production during adulthood. Concomitant decline in T-cell loss compensates for decreased generation rates. We investigated putative mechanisms underlying age-related changes in homeostatic regulation of CD4+ naive T-cell turnover, using mass cytometry to profile candidate signaling pathways involved in T-cell activation and proliferation relative to CD31 expression, a marker of thymic proximity for the CD4+ naive T-cell population. We show that basal nuclear factor κB (NF-κB) phosphorylation positively correlated with CD31 expression and thus is decreased in peripherally expanded naive T-cell clones. Functionally, we found that NF-κB signaling was essential for naive T-cell proliferation to the homeostatic growth factor interleukin (IL)-7, and reduced NF-κB phosphorylation in CD4+CD31− naive T cells is linked to reduced homeostatic proliferation potential. Our results reveal an age-related decline in naive T-cell turnover as a putative regulator of naive T-cell diversity and identify a molecular pathway that restricts proliferation of peripherally expanded naive T-cell clones that accumulate with age.

MORPHO-FUNCTIONAL CHANGES OF THYMUS AND CONTENTS OF BLOOD LYMPHOCYTE SUBPOPULATIONS IN FEMALE WISTAR RATS WITH DIFFERENT RESISTANCE TO HYPOXIA IN SYSTEMIC INFLAMMATORY RESPONSE

Hypoxia and immune reactions are closely interrelated at molecular, cellular and organism levels, and the individuals differ in resistance to oxygen deficiency. Animals with high and low resistance to hypoxia have different adaptive capabilities and predisposition to the development of inflammatory diseases. Data on the individual characteristics of hypoxia resistance in female laboratory animals and humans, and its relationship to immune system reactions in both normal conditions and inflammatory diseases are not available in the literature. It is known, however, that acute infectious and inflammatory diseases develop at lesser rates and are less severe in women and female laboratory animals than in males, which can be explained by higher resistance of females to hypoxia. The aim of our study is to reveal the features of morpho-functional thymus changes, and subpopulation of peripheral blood lymphocytes in systemic inflammatory response induced by LPS administration to female Wistar rats with different resistance to hypoxia. Resistance of mature female Wistar rats to hypoxia was determined as a survival period in a ventilated lowpressure chamber simulating high altitude condition (11 500 m). The rats with a lifetime “at high altitude” of > 180 s have been classified as highly resistant to hypoxia, and the animals surviving for < 20 seconds were designated low-resistant. One month after determining the hypoxia resistance, the females were injected intraperitoneally with E. coli O26:B6 lipopolysaccharide (LPS) at a dose of 1.5 mg/kg during the dioestrus phase. The animals were withdrawn from the experiment by i/m Zoletyl injection (15 mg/kg) one day after LPS administration. The relative volume fractions of thymic cortex and medulla were evaluated; the areas of necrosis were determined in the liver, and the number of neutrophils in the interalveolar septa was counted in the lungs. The serum contents of corticosterone, testosterone, TGF-β were determined. A flow cytometry evaluation of the relative and absolute numbers was performed for major subpopulations of lymphocytes in peripheral blood. The number of apoptotically dying cells of the thymus was assessed. For statistical processing of the obtained data, the Statistica 8.0 software was applied, using criteria of multiple comparisons by Kruskal–Wallis and Dann. The differences were considered statistically significant at p < 0.05.In both high- and low-resistant to hypoxia females, the development of a systemic inflammatory -response was accompanied by a moderately severe thymic involution, apoptosis of thymocytes, an increase in the absolute number of NK, and rise of testosterone and corticosterone contents. LPS injection into low-resistant rats, if compared to females highly resistant to hypoxia, led to more severe manifestations of systemic inflammation, i.e., a pronounced inflammatory reaction in the lungs and a more extensive liver necrotic area accompanied by increased absolute numbers of regulatory T lymphocytes and T helper cells, and more pronounced thymic accidental involution with apoptotic death of thymocytes. Systemic manifestations of inflammation were less pronounced in hypoxia-resistant female rats, which was apparently associated with activation of lymphocyte migration from the thymus and blood to the inflammation focus, and development of more effective immune response.Conclusion: immune reactions in the systemic inflammatory response induced by LPS in female Wistar rats depend on individual resistance to hypoxia. These data should be used to develop approaches to personalized therapy of infectious and inflammatory diseases in women.

Thymus Imaging Detection and Size Is Inversely Associated With Metabolic Syndrome and Frailty in People With HIV.

BackgroundPeople with HIV (PWH) may experience accentuating aging in relation to immuno-activation. Little is known regarding thymus (THY) involution in this process. We sought to investigate the relationship between THY imaging detection/size and clinically relevant aging outcomes such as metabolic syndrome (MetS), multimorbidity (MM), and frailty in PWH.MethodsThis was a cross-sectional observational study including 665 HIV patients (81% males; median age, 53 years) attending Modena HIV Metabolic Clinic from 2014 to 2017. They underwent thoracic computed tomography scan as part of the medical assessment for cardiovascular disease, in which THY detection and size were reported using a semiquantitative score. Outcome measures were MetS, MM, and frailty.ResultsTHY was detected in 27.0% of subjects; 71.1% showed THY size of grade 1–2, and 28.9% exhibited grade ≥3. Covariates that inversely correlated with THY detection were age, male gender, body mass index (BMI), and HIV duration. Covariates that inversely correlated with MetS were age, HIV duration, BMI, and THY grade 1–2. Covariates that inversely correlated with MM were age, HIV duration, and CD4 nadir. Covariates that inversely correlated with frailty were age, HIV duration, CD4 nadir, BMI, and THY detection.ConclusionsTHY is inversely associated with MetS and frailty in PWH.

Transcription-Related Dynamics from Immune Disability into Endogenous Innovation.

So far, thymus involution in adults is believed to be irreversible, and endogenous innovation for thymus‐related immunodeficiency remains to be an intractable puzzle. With the expectation of addressing this dilemma, human ovarian surface epithelium (OSE) has been reengineered as epithelial‐mesenchymal transition (EMT)‐tridimensional‐spheroid biologics (ETSB) using a dynamic EMT‐3D‐floating system along with 160 Gy X‐ray‐amelioration, which inoculates subcutaneously into aging rhesus and athymic Balb/cnu/nu mice. Herein, it is bioinformatically validated that ETSB can reset Clock/Arntl‐Per3/Tim molecule rhythm dynamics to re‐prime thymus residual (parathyroid or fatty‐like invalid vesicles yet no thymic architecture) to evolutionary transcription with overall cortex‐medulla endogenized by TECs undergoing MET/EMT reversion. Rhythm dynamics immediately resettles the bHLH‐LTβR‐NFκB‐RelA/B loop as a cascade to provoke the core immune microenvironment for multifunctional innovation of dynamic TCR orchestration, with harmonious naïve T‐subsets and TRECs renewals (P < 0.005). Subsequently, peripheral biological burden and tumor metastasis dynamics are addressed by innovative TCR‐defense/attack dynamics quickly (P < 0.005 vs Control), yet without autoimmune indication to hosts. Moreover, a functional blockade of core‐rhythm dynamics deeply impedes the endogenous innovation of invalid thymus residual. Thus this study may help pioneer a prospective strategy to innovate panoramic central‐peripheral immune microenvironments and defense dynamics for immune‐deficient/aging victims.

Primary Mediastinal Nodal and Extranodal Non-Hodgkin Lymphomas: Current Concepts, Historical Evolution, and Useful Diagnostic Approach: Part 2.

Primary mediastinal non-Hodgkin lymphomas (PM-NHLs) represent ∼5% of all non-Hodgkin lymphomas (NHLs) and comprise lymphomas of B-cell and T-cell origin. PM-NHLs are defined as involvement of mediastinal lymph nodes, thymus, and/or mediastinal organs (heart, lung, pleura, pericardium) by NHL without evidence of systemic disease at presentation. The clinical scenario is variable and depends on the lymphoma subtype. The radiologic presentation is also variable ranging from a mediastinal mass with or without superior vena cava syndrome, a pleural or a cardiac mass associated with effusion, or as an effusion only. The diagnosis of PM-NHLs can only be established by microscopic evaluation, and therefore, general pathologists should be aware of these tumors and familiar with their diagnostic approach. The most common anterior mediastinal NHLs (90% to 95%) are primary mediastinal (PM) large B-cell lymphoma and T-lymphoblastic lymphoma. Thymic marginal zone lymphoma and mediastinal gray zone lymphoma are very rare. The remainder PM-NHLs involving middle or posterior mediastinum include diffuse large B-cell lymphoma (DLBCL) and rare cases of T-cell lymphoma, including anaplastic large cell lymphoma and breast implant-associated anaplastic large cell lymphoma extending to the anterior mediastinum. Primary pleural and cardiac NHLs are mostly DLBCLs. Other rare subtypes of PM-NHLs include DLBCL associated with chronic inflammation/pyothorax-associated lymphoma, fibrin-associated DLBCL (both Epstein-Barr virus positive), and pleural and/or pericardial primary effusion lymphoma (human herpesvirus-8 positive/Epstein-Barr virus positive). We review the historical aspects, epidemiology, clinicoradiologic features, histopathology, immunohistochemistry, differential diagnosis, and relevant cytogenetic and molecular features of the remaining mediastinal B-cell lymphomas, including primary thymic marginal zone lymphoma of the mucosa-associated lymphoid tissue type, other PM small B-cell lymphomas, PM plasmacytoma, and the most relevant PM T-cell lymphomas.

Primary Mediastinal Nodal and Extranodal Non-Hodgkin Lymphomas: Current Concepts, Historical Evolution, and Useful Diagnostic Approach: Part 1

Primary mediastinal non-Hodgkin lymphomas (PM-NHLs) represent ~5% of all NHLs and comprise lymphomas of B-cell and T-cell origin. PM-NHLs are defined as involvement of mediastinal lymph nodes, thymus, and/or mediastinal organs (heart, lung, pleura, pericardium) by NHL without evidence of systemic disease at presentation. The clinical scenario is variable and depends on the lymphoma subtype. The radiologic presentation is also variable ranging from a mediastinal mass with or without superior vena cava syndrome, a pleural or a cardiac mass associated with an effusion, or as an effusion only. The diagnosis of PM-NHLs can only be established by microscopic evaluation, and therefore, general pathologists should be aware of these tumors and familiar with their diagnostic approach. The most common anterior mediastinal NHLs (90% to 95%) are primary mediastinal large B-cell lymphoma and T lymphoblastic lymphoma. Thymic marginal zone lymphoma and mediastinal gray zone lymphoma are very rare. The remainder PM-NHLs involving middle or posterior mediastinum include diffuse large B-cell lymphoma (DLBCL) and rare cases of T-cell lymphoma, including anaplastic large cell lymphoma and breast implant-associated anaplastic large cell lymphoma extending to the anterior mediastinum. Primary pleural and cardiac NHLs are mostly DLBCLs. Other rare subtypes of PM-NHLs include DLBCL associated with chronic inflammation/pyothorax-associated lymphoma, fibrin-associated DLBCL (both EBV), and pleural and/or pericardial primary effusion lymphoma (HHV-8/EBV). We review the historical aspects, epidemiology, clinico-radiologic features, histopathology, immunohistochemistry, differential diagnosis, and relevant cytogenetic and molecular features of PM (thymic) LBCL, PM "nonthymic" DLBCL, BCL, unclassifiable, with features intermediate between DLBCL and classic Hodgkin lymphoma (mediastinal gray zone lymphoma), DLBCL associated with chronic inflammation (pyothorax-associated lymphoma), fibrin-associated DLBCL, and primary effusion lymphoma. This review represents the first part of 2 manuscripts covering PM-NHLs.

Clinicopathologic findings in children who died following Klebsiella pneumoniae bloodstream infection

Klebsiella pneumoniae bloodstream infection (KPBSI) is strongly linked to hospitalisation and can lead to significant morbidity and mortality. There is little data describing the autopsy findings of KPBSI in children. We conducted a retrospective review of clinicopathologic findings of children who died during the course of KPBSI at a children's hospital in Cape Town, South Africa. Fifteen hospitalised children who died and had autopsies were included in this analysis. Their median age (interquartile range, IQR) was 4 (1–22) months, 2 (20%) were HIV-infected, and 10 (67%) were moderately or severely underweight. The median time to death from the time of positive blood culture was 1 (IQR 0–5) day. Notable autopsy findings were sepsis-induced multiorgan failure in many cases including thymic involution, oesophageal erosions, adrenal haemorrhage, acute tubular necrosis and lung parenchymal destruction. Other histologic findings included disseminated intravascular coagulopathy, necrotising inflammation in many organs; and in four of five children biofilm formation. KPBSI may cause widespread necrotic tissue.