Health Consequences of Thymus Removal in Adults

Rejuvenation of thymus and modulation of local and systemic T cell responses in animal model of Alzheimer's disease following cell therapy using sperm head

In Alzheimer's disease (AD), the balance of T cell response in the brain is dysregulated due to increase of T-helper 1 (Th1) and Th17 over Th2 response. Considering the link between local and systemic immune response, it is important to modulate brain pattern of T cell in harmony with the systemic immune system. Some studies also attempted to rejuvenate thymus which is affected in AD. Based on immunologic properties of sperm, previous studies demonstrated significant therapeutic effects of sperm head on the brain AD animal models. In this study, pattern of T cell response was determined locally in the brain and systemically in the cervical lymph nodes, and spleen. Thymus health status was also evaluated using forkhead box N1 (FOXN1). The results were compared between control and sperm head-treated AD model animals. In the brain, cervical lymph nodes, and spleen, treatment with sperm head significantly decreased interferon-gamma (IFN-γ) along with interleukin-17 (IL-17) and increased IL-4, representative of Th1, Th17, and Th2, respectively. Surprisingly, in the sperm head-treated AD model animals, significant decrease was observed in regulatory T cells (Treg), represented by cluster of designation 4 (CD4), CD25, and FOXP3 high expression. Interestingly, sperm head had significant rejuvenation effects on the thymus represented by increase in FOXN1. The results show that sperm head could deviate chronic inflammation towards a constructive inflammation. Results suggest revision of our attitude towards the inflammation as the results suggest that boosting inflammation can be more efficient than suppressing inflammation for treatment of AD.

Low T cell diversity associates with poor outcome in bladder cancer: A comprehensive longitudinal analysis of the T cell receptor repertoire

T cells are crucial effector cells in the endogenous defense against cancer, yet the clinical impact of their quantity, diversity, and dynamics remains underexplored. Here, we investigate the clinical relevance of the T cell receptor (TCR) repertoire in patients with bladder cancer. In advanced-stage disease, low pre-treatment peripheral TCR diversity is associated with worse overall survival (p = 0.024), particularly when coupled with low circulating T cell fractions (p = 0.00049). These low-diversity repertoires are dominated by hyper-expanded clones that persist throughout treatment. Further longitudinal analysis reveals reductions in TCR diversity after treatment, indicating adverse effects on the immune system. In early-stage disease, immunotherapy increases TCR diversity in patients with good outcomes. Furthermore, single-cell sequencing identifies most hyper-expanded clones as cytotoxic T cells, while non-expanded clones are predominantly naive T cells. Overall, this highlights TCR diversity as a promising biomarker, offering opportunities for tailored oncological treatments to enhance clinical outcomes.

Mortality risk in patients with myasthenia gravis

Introduction

Although some reports link Myasthenia Gravis to higher mortality, the evidence remains contradictory and unclear. Real-life data is limited primarily due to challenges in selecting control groups and mitigating bias. Additionally, a revised mortality assessment should be conducted due to recent advancements in Myasthenia Gravis treatments over the past decade, including new biological therapies and the impact of the COVID-19 pandemic from 2020 to 2023.

Methods

We conducted a retrospective analysis of all patients diagnosed with Myasthenia Gravis at our tertiary center between 2000 and 2023, extracting mortality and clinical features compared to two age- and sex-matched control groups of neurological or rheumatologic patients.

Results

We identified 436 Myasthenic patients and 2,616 controls (1308 in each control group). Myasthenia Gravis mortality was 14% at 5 years (61/422) and 21% at 10 years (87/422). Mortality was significantly higher than control groups (p < 0.001). Intubations during myasthenic crisis were linked to higher mortality (p = 0.002). Bulbar weakness at presentation showed higher mortality but did not reach clinical significance. We compared the mean age at death in MG patients to national life expectancy benchmarks using a one-sample Z-test, revealing significantly younger age at death in both males (78.3 vs. 81.6 years, p = 0.009) and females (76.5 vs. 85.2 years, p < 0.00001). Patients with normal thymic pathology showed better outcomes and lower mortality after thymic removal (p < 0.0001). The primary cause of death was linked to infections, significantly correlated with chronic steroid use.

Discussion

In conclusion, patients with Myasthenia Gravis had higher mortality rates. Thymic removal reduced mortality, while intubation is associated with increased mortality risk.

CD103+ T Cells Eliminate Damaged Alveolar Epithelial Type II Cells Under Oxidative Stress to Prevent Lung Tumorigenesis

The nexus between aging-associated immune deteriorations and tumorigenesis of lung cancers remains elusive. In a mouse model with Med23 depletion in T cells (Med23 -/-), it is found a strong association between the decline of CD103+ T cells and spontaneous alveolar epithelial type II cell (AT2 cell)-originated lung adenocarcinomas. The reduction of CD103+ T cells in the lung results in an accumulation of AT2 cells bearing oxidative damages, which appears to be the major origin of the lung adenocarcinoma. Functional experiments reveal CD103+ T cells can eradicate oxidative-damage-bearing AT2 cells as well as ROS-dependent, KRAS (G12D)-driven tumorigenesis. In vitro co-cultures prove CD103+ T cells, especially CD103+ CD8+ T cells, exhibit a killing capacity that matches the oxidative stress level in the target cells. In aged animals, it is found the abundance of CD103+ CD8+ T cells in the lung declines with age, accompanied by an accumulation of oxidative-damage-bearing AT2 cells. Collectively, the study establishes the vital function of CD103+ T cells in surveilling epithelial cells under oxidative stress to prevent malignancies, and unravels a potential immuno-dysregulation in the aged lung which contributes to tumorigenesis.

Lymph nodes link sex-biased immune aging to compromised antigen recognition

A diverse naive CD8 T cell repertoire is essential to provide broad protection against infection and cancer. Aging diminishes naive T cells, reducing potential diversity and leading to lymph node contraction. Here, we revealed that this decline occurs earlier in males, resulting in significant sex differences in immunity during middle age. Earlier in life, naive CD8 T cells in males become virtual memory cells prone to premature senescence. Due to androgen-driven thymic atrophy in males, naive CD8 T cells are insufficiently replenished. Therapeutic thymus rejuvenation via testosterone ablation restored naive CD8 T cells in lymph nodes of middle-aged male mice, leading to enhanced tumor recognition. These findings show the crucial role of sex and age on lymph node T cell repertoires and suggest potential strategies to restore immune function in males during aging.

Paracrine FGF21 dynamically modulates mTOR signaling to regulate thymus function across the lifespan

Consequences of age-associated thymic atrophy include declining T-cell responsiveness to pathogens and vaccines and diminished T-cell self-tolerance. Cortical thymic epithelial cells (cTECs) are primary targets of thymic aging, and recent studies suggested that their maintenance requires mTOR signaling downstream of medullary TEC (mTEC)-derived growth factors. Here, to test this hypothesis, we generated a knock-in mouse model in which FGF21 and mCherry are expressed by most mTECs. We find that mTEC-derived FGF21 promotes temporally distinct patterns of mTORC1 and mTORC2 signaling in cTECs, promotes thymus and individual cTEC growth and maintenance, increases T-cell responsiveness to viral infection, and diminishes indicators of peripheral autoimmunity in older mice. The effects of FGF21 overexpression on thymus size and mTOR signaling were abrogated by treatment with the mTOR inhibitor rapamycin. These results reveal a mechanism by which paracrine FGF21 signaling regulates thymus size and function throughout the lifespan, as well as potential therapeutic targets for improving T-cell function and tolerance in aging.

Enhanced paracrine action of FGF21 in stromal cells delays thymic aging

Age-related thymic involution precedes aging of all other organs in vertebrates and initiates the process of declining T cell diversity, which leads to eventual immune dysfunction. Whether FGF21, a liver-derived pro-longevity hormone that is also produced in thymic stroma, including by adipocytes, controls the mechanism of thymic demise is incompletely understood. Here, we demonstrate that elevation of FGF21 in thymic epithelial cells (TECs) and in adipocytes protects against thymic aging, whereas conditional hepatic overexpression did not impact thymic biology in aged mice. Notably, elevation of thymic FGF21 increased naïve CD8 T cells in aged animals and extended healthspan. Mechanistically, thymic FGF21 overexpression elevated TECs and reduced fibroadipogenic cells. Ablation of β-klotho, the obligatory co-receptor for FGF21 in Foxn1+ TECs, accelerated thymic aging, suggesting regulation of TECs by FGF21 is partially required for thymic lymphopoiesis. These findings establish that paracrine FGF21 improves thymic function and delays immune aging.

American Association of Clinical Endocrinology Consensus Statement on Management of Multiple Endocrine Neoplasia Type 1

OBJECTIVE

This document presents the findings of the American Association of Clinical Endocrinology (AACE) on the diagnosis, management, and surveillance of patients with multiple endocrine neoplasia type 1 (MEN1) and associated tumors. The task force included a diverse group of experts in endocrinology, oncology, genetics, surgery, and patient representation. A comprehensive literature review was conducted to address key issues related to the evaluation, surveillance, and treatment of MEN1-related tumors.

METHODS

The task force, comprised of 9 members with expertise in endocrinology, surgery, medical oncology, genetics, and patient advocacy, collaborated to develop guidance for the evaluation, surveillance, and management of MEN1-associated tumors. Consensus was defined as ≤1 dissenting vote and significant majority as ≥75%. Relevant studies were identified through a literature review process, and consensus statements were based on the available evidence.

RESULTS

The task force deliberated on the surveillance, evaluation, and management of MEN1-related tumors including parathyroid, pituitary, and gastroenteropancreatic neuroendocrine tumors and other tumors of relevance. The document also addresses the indications for MEN1 genetic testing.

CONCLUSIONS

This consensus statement aims to offer evidence-informed guidance for health care providers involved in the care of patients with MEN1 and associated tumors. It provides guidance on diagnostic tools, genetic testing criteria, imaging techniques, surgical interventions, and posttreatment monitoring. The practical, patient-centered approach outlined in this document is intended to improve outcomes for individuals with MEN1 and other high-risk endocrine tumors.

Survival and autoimmune risks post-thymectomy

Background and objectives

Recent studies have raised concerns about thymectomy's deleterious effects. However, this conclusion was not exclusive to patients with myasthenia gravis (MG). The objective of this study was to test this hypothesis in thymectomy patients, regardless of their MG status.

Methods

We conducted a retrospective case-control study to analyze clinical and radiological data from 1 January 2010 to 30 November 2023. Patients were divided into four groups: MG with (MG-Thy) or without thymectomy (MG-NO-Thy); thoracoscopic surgery without thymectomy (Surgery-NO-Thy) and Non-MG with thymectomy (Non-MG-Thy).

Results

We identified a total of 456 patients (n=41, MG-Thy; n= 278, MG-NO-Thy; n=65, Non-MG-Thy; and n=72, Surgery-NO-Thy). The median ages were as follows: MG-Thy, 45.6 years (range: 22-79); MG-NO-Thy, 65 years (13-93); Non-MG-Thy, 59.8 (19-85) years; and Surgery-NO-Thy, 59.8 years (range: 19-85) (p<0.001). The median follow-up times were 5.5 years in MG-Tym, 3 in MG-NO-Thy, 3.9 in Non-MG-Thy, and 4.7 years in Surgery-NO-Thy. A thymic mass was detected with chest computed tomography (CT) in 56% (23/41) of the MG-Thy cohort and in all the Non-MG-Thy cohort. Thymic pathology in the MG-Thy group showed normal/fat atrophic thymus in 31.7% (13/41), hyperplasia in 26.8% (11/41), thymic cyst in 2.4% (1/41), and malignant in 39% (16/41). Thymic pathology in the non-MG group showed hyperplasia, fat, or normal thymus in 16.9% (11/65); thymic cyst in 18.5% (12/65); malignant thymoma in 60% (39/65); and others in 4.6% (3/65). The death rate was the lowest in the MG-Thy group, compared to the non-MG groups and the MG-No-Thy group. Specifically, death occurred in zero cases in the MG-Thy group, while it occurred in 13.8% (9/65) of the thymectomized non-MG group and in 35.6% (99/278) of the MG-without thymectomy group. Excluding late-onset MG patients (LOMG), the death incidence was 14.4% (15/104). The prevalence of autoimmune diseases before thymectomy was 14.6% (6/41) in the MG-Thy group versus 12.3% (8/65) in the Non-MG-Thy group, with three new cases post thymectomy in non-MG group. Post thymectomy cancer incidence was zero in the MG-Thy group, versus 16.2% (45/278) in the MG-NO-Thy group.

Conclusion

The benefits of thymectomy outweigh potential risks for patients with MG or patients with thymic malignancies. Incidental thymectomy should be avoided. This call for reevaluation of thymectomy especially for non-neoplastic causes.

Management of primary hyperparathyroidism in MEN1: From initial subtotal surgery to complex treatment of the remaining gland

Multiple endocrine neoplasia type 1 (MEN1) is a rare genetic disease with autosomal dominant transmission, which can cause various tumors, particularly endocrine, in a given patient. Primary hyperparathyroidism (PHPT) is the most common and earliest manifestation, leading to surgery before the age of 50 in most patients. Biological severity and renal and/or bone complications dictate the timing of parathyroid surgery. The objective is to correct hypercalcemia to prevent impact, while minimizing the risk of hypoparathyroidism. The most widely recommended procedure is subtotal parathyroidectomy (3 or 3.5 glands removed), with thymic horn resection via a cervical route. The development of imaging techniques, however, makes it possible to discuss partial surgery (resection of 1 or 2 glands) on a case-by-case basis depending on preoperative imaging and other elements such as patient age. Finally, hypercalcemia recurrence after initial surgery is a common feature of MEN1, and management of the remaining gland is challenging with various options: reoperation, calcimimetics and US-guided ablation or therapeutic abstention.

Vitamin A Metabolism and Resistance of Hepatic Metastases to Immunotherapy

The liver is an immune-tolerant organ, allowing for organ transplantation with less immune suppression compared with other organs. It also provides fertile soil for tumor metastases, which tend to be more resistant to checkpoint blockade immunotherapy than metastases in other organs. This resistance may result from the sum of incremental evolutionary adaptions in various cell types to prevent overaction to antigens absorbed from the gut into the portal circulation or it might involve a central mechanism. Here, we propose that metabolism of vitamin A, which is highly concentrated in the liver, is a root source of tolerance and resistance of hepatic metastases to checkpoint blockade. Suppression of retinoic acid synthesis from vitamin A with disulfiram may mitigate tolerance and produce enhanced immunotherapy treatment results for patients with liver metastases.

Recirculating regulatory T cells mediate thymic regeneration through amphiregulin following damage

Thymic injury associated with disease or cancer treatment reduces T cell production and makes patients more vulnerable to infections and cancers. Here, we examined the role of regulatory T (Treg) cells on thymic regeneration. Treg cell frequencies increased in the thymus in various acute injury models. Depletion of Treg cells impaired thymic regeneration, impacting both the thymocyte compartment and the stromal cell compartment; adoptive transfer of Treg cells enhanced regeneration. Expansion of circulating Treg cells, as opposed to that of tissue resident or recent thymic emigrants, explained this increase, as seen using parabiotic and adoptive transfer models. Single-cell analyses of recirculating Treg cells revealed expression of various regenerative factors, including the cytokine amphiregulin. Deletion of amphiregulin in these Treg cells impaired regeneration in the injured thymus. We identified an analogous population of CD39+ICOS+ Treg cells in the human thymus. Our findings point to potential therapeutic avenues to address aging- and treatment-induced immunosuppression.

Viruses tipping the scales: The role of the CD4/CD8 ratio in determining viral outcome

Here we review recent data on how animal viruses alter the T cell dynamics, and how stressed T cell populations alter viral disease outcomes. The CD4/CD8 ratio of T cells is regulated by the thymus well into adulthood, and determined by both host genetics and environmental exposures. Human and animal data now show many chronic viral infections interact with this ratio and Immune Health Grades, but this raises new questions and justifies new experimental systems. Immune Health Grades and the ratio generally can quantify subtle immunodeficiency for viral infections. Whether or not an animal recovers from a viral infection, and how carcinogenisis proceeds for certain oncogenic viral infections can now be traced back to how "stressed that animal's immune system is as judged by a low CD4/CD8 ratio or elevated Immune Health Grade. We provide this review to encourage basic science virologists using animal models and veterinary virologists to further explore the interactions between the CD4/CD8 T cell ratio and viruses to improve both human and veterinary health.

Diagnostic and prognostic relevance of inflammatory markers in surgically treated thymic epithelial tumors: An international multicenter study

BACKGROUND

Complementary prognostic markers are needed in thymic epithelial tumors (TETs) to aid patient stratification and determine the most appropriate follow-up strategies. This study aimed to assess the diagnostic and prognostic relevance of blood-based inflammatory markers in a large cohort of surgically treated TET patients.

MATERIAL AND METHODS

A total of 743 TET patients who underwent surgical resection between 1999-2021 were included in this multicenter study. Inflammatory markers were recorded from the most recent preoperative blood cell count prior to surgery. Measured variables were rescaled and harmonized to obtain comparable values across the participating centers.

RESULTS

Preoperative CRP was significantly higher in TET patients with increased tumor size (vs. those with T1 tumors, p = 0.035). Likewise, neutrophil-to-lymphocyte ratio (NLR) (p = 0.002) and platelet-to-lymphocyte ratio (PLR) (p < 0.001) were both significantly higher in thymic carcinomas than in thymomas. Notably, increased NLR and PLR were mainly attributed to significantly decreased lymphocyte levels in thymic carcinoma patients. Concerning survival outcomes, we found that elevated PLR and fibrinogen influenced overall survival (OS) (p = 0.002 and p = 0.018, respectively) and cause-specific survival (CSS) (p = 0.002 and p = 0.009, respectively) independently of other variables in our multivariate models, and they constituted negative prognosticators in TETs. Elevated CRP had an independent negative impact only on OS. Although elevated NLR was linked with impaired prognosis in our univariate model (p = 0.008), its independent prognostic significance could not be validated.

CONCLUSIONS

Using the so-far largest cohort of surgically treated TET patients, our study demonstrates that CRP, PLR, and NLR have diagnostic significance in TETs, while elevated PLR and fibrinogen constitute independent negative prognosticators for OS and CSS. Accordingly, the current multicenter study offers additional guidance in developing personalized surveillance protocols in thymoma and thymic carcinoma.

Thymus ad astra, or spaceflight-induced thymic involution

Spaceflight imposes a constellation of physiological challenges-cosmic radiation, microgravity, disrupted circadian rhythms, and psychosocial stress-that critically compromise astronaut health. Among the most vulnerable organs is the thymus, a cornerstone of immune system functionality, tasked with generating naive T cells essential for adaptive immunity. The thymus is particularly sensitive to spaceflight conditions, as its role in maintaining immune homeostasis is tightly regulated by a balance of systemic and local factors easily disrupted in space. Cosmic radiation, an omnipresent hazard beyond Earth's magnetosphere, accelerates DNA damage and cellular senescence in thymic epithelial cells, impairing thymopoiesis and increasing the risk of immune dysregulation. Microgravity and circadian rhythm disruption exacerbate this by altering immune cell migration patterns and stromal support, critical for T-cell development. Psychosocial stressors, including prolonged isolation and mission-induced anxiety, further compound thymic atrophy by elevating systemic glucocorticoid levels. Ground-based analogs simulating cosmic radiation and microgravity have been instrumental in elucidating mechanisms of thymic involution and its downstream effects on immunity. These models reveal that long-duration missions result in diminished naive T-cell output, leaving astronauts vulnerable to infections and possibly at high risk for developing neoplasia. Advances in countermeasures, such as pharmacological interventions targeting thymic regeneration and bioengineering approaches to protect thymic architecture, are emerging as vital strategies to preserve immune resilience during prolonged space exploration. Focusing on the thymus as a central hub of immune vulnerability underscores its pivotal role in spaceflight-induced health risks. Understanding these dynamics will not only enhance the safety of human space missions but also provide critical insights into thymus biology under extreme conditions.

Pediatric Transplant and Cellular Therapy Consortium RESILIENT Conference on Pediatric Chronic Graft-versus-Host Disease Survivorship after Hematopoietic Cell Transplantation: Part II. Organ Dysfunction and Immune Reconstitution Considerations for Children with Chronic Graft-versus-Host Disease after Hematopoietic Cell Transplantation

While highly morbid forms of chronic graft versus host disease (cGVHD) and severe late effects of allogeneic hematopoietic cell transplantation (HCT) can impact children and adults alike, unique considerations arise in pediatric cases regarding diagnosis, monitoring, treatment, and likelihood of resolution. As children can present with atypical features of cGVHD and with more significant disease due to inability to communicate symptoms, they may be at increased risk for highly morbid forms of cGVHD and incur greater subsequent late effects, which may be more pronounced in those with underlying chromosomal breakage syndromes, with higher prevalence in pediatric HCT recipients. The long-term effects of cGVHD and its therapies include impaired immune reconstitution, leading to increased risks of infection and secondary malignant neoplasms. However, children also have the greatest potential for full immune reconstitution, due to thymus recovery that could impact the timing of vaccination with respect to tolerance and restoration of optimal immunity. Developing strategies to mitigate the late effects incurred with, and as a result of, cGVHD is of critical importance. The working group recommends surveillance strategies for late effects in patients with cGVHD, increased utilization of emerging diagnostic tools, integration of monitoring for cGVHD treatment response, and development of new treatments and specifies aims of future research endeavors.

Multilocular Thymic Cyst with High F18 Fluorodeoxyglucose Uptake and Rheumatoid Arthritis: A Case Report

Background: multilocular thymic cysts are uncommon acquired cysts in the anterior mediastinum caused by incomplete thymic involution. They may be associated with autoimmune diseases, such as rheumatoid arthritis and systemic sclerosis. Methods: a 61-year-old man with a history of rheumatoid arthritis for 8 years was referred to our unit because of a multiloculated mass in the anterior mediastinum with a high F18 fluorodeoxyglucose uptake at PET-CT scan. Histology showed a multilocular thymic cyst with lymphoid tissue, organized in germinal centers and internodal areas. Results: rheumatoid arthritis-related symptoms progressively disappeared after the excision of the mass. Conclusions: to our knowledge, this is the first report in the English language of rheumatoid arthritis symptoms improvement after multilocular thymic cyst surgical removal.

PD-1 prelimits both the cytotoxic and exhaustion potential in thymic CD8+ T cells and impacts the maintenance of peripheral tumor immunity

Durable T cell immunity against cancer depends on the continual replenishment of effector CD8+ T cells. Thymic output has been correlated with favorable prognosis in cancer patients across a range of ages, suggesting that the thymus is an important source for replenishing T cells capable of controlling cancer progression. However, the effector potential of thymic mature CD8+ T cells and their regulation have not been clearly defined. In this study, we identified the ability of thymic single positive CD8+ T cells to gain effector potential after thymic selection, but they are subject to the regulation of PD-1. We found a previously undisclosed role of PD-1 in limiting both the cytotoxic and exhaustion potential of thymic and peripheral CD8+ T cells. Our results show that although PD-1 inhibition facilitates the expansion of effector CD8+ T cells, effector CD8+ cells gradually lose their antitumor activity within tumor tissues due to advanced exhaustion in the absence of PD-1. Thus, although the preset effector potential in thymic mature CD8+ T cells allows them to rapidly respond to malignant cells in the periphery, PD-1, as a checkpoint, is embedded in the thymic mature CD8+ T cells after positive selection to balance their effector function from exaggeration and exhaustion. Therefore, we propose that a strategy capable of upholding the cytotoxic capacity and avoiding exhaustion of CD8+ T cells during the early stages of PD-1 inhibition therapy is needed to achieve durable antitumor immunity.

Is thymectomy necessary during parathyroidectomy for secondary hyperparathyroidism in patients with end-stage kidney disease?

BACKGROUND

Guidelines recommend thymectomy at the time of parathyroidectomy for secondary hyperparathyroidism to reduce the likelihood of persistent or recurrent disease. We sought to determine the frequency of thymectomy and explore its impact on recurrence of secondary hyperparathyroidism.

METHODS

Using TriNetX, a multi-institutional electronic health record and insurance claims network, we conducted a retrospective cohort study of adults with secondary hyperparathyroidism who underwent parathyroidectomy with or without thymectomy from 2005 to 2023. Rates of thymectomy, repeat parathyroidectomy, and calcimimetic use were compared between cohorts. Recurrence was defined by parathyroid hormone ≥600 pg/mL, reoperation, or calcimimetic use. Current Procedural Terminology and SNOMED codes for parathyroidectomy did not distinguish between subtotal compared with total parathyroidectomy.

RESULTS

Among 2,564 patients underwent surgery for secondary hyperparathyroidism, 2,272 (88.8%) underwent parathyroidectomy and 287 (11.2%) underwent parathyroidectomy + thymectomy. Rates of parathyroidectomy + thymectomydecreased over time, from 25.5% in 2005 to 10.1% in 2023. Preoperatively, there was no difference in mean preoperative parathyroid hormone levels, serum calcium or calcidiol, or cinacalcet use. Postoperatively, there was no difference in the mean parathyroid hormone level (183 pg/mL vs 180 pg/mL, P = .88), odds of calcimimetic use (odds ratio, 0.94, 95% confidence interval, 0.64-1.39), reoperation within 5 years postoperatively (odds ratio 0.72, 95% confidence interval 0.39-1.36), or rates of kidney transplantation (odds ratio 1.03, 95% confidence interval 0.67-1.60) between parathyroidectomy and parathyroidectomy + thymectomy groups.

CONCLUSION

Thymectomy is infrequently performed during parathyroidectomy for secondary hyperparathyroidism, and rates continue to decline. Although thymectomy at time of parathyroidectomy did not appear to decrease recurrence, future studies should include extent of parathyroidectomy to determine impact of thymectomy on recurrence in secondary hyperparathyroidism.

History of the Thymus: From a Vestigial Organ to the Programming of Immunological Self-Tolerance

This introductive chapter presents the most important disruptions of concepts concerning the thymus since its discovery in Antique Greece. For centuries, the thymus was considered as a vestigial organ, and its role in T-cell differentiation was proposed only in the 1960s. Most recent studies attribute to the thymus an essential and unique role in programming central immunological self-tolerance. The basic mechanism implicated in this function is the transcription in the thymic epithelium of genes encoding precursors of neuroendocrine-related and tissue-restricted self-peptides. Their processing leads to the presentation of self-antigens by the major histocompatibility complex (MHC) machinery expressed by thymic epithelial and dendritic cells. Already during foetal life, this presentation promotes negative selection of T lymphocytes harbouring a receptor with high affinity for MHC/self-peptide complexes. Mainly after birth, this presentation also drives the generation of regulatory T cells specific for these complexes. Numerous studies, as well as the identification of Aire and Fezf2 genes, have shown that a thymus defect plays a crucial role in the development of autoimmunity. The discovery of the central tolerogenic action of the thymus revolutionized the whole field of immunology, and such knowledge will pave the way for innovative tolerogenic therapies against autoimmunity, the so heavy tribute paid by mankind for the extreme diversity and efficiency of adaptive immunity.

The Association Between Myasthenia Gravis and Higher Extrathymic Cancer Risk

BACKGROUND

Myasthenia gravis (MG) is strongly associated with thymic tumors, but whether it is also associated with extrathymic cancers is debatable or whether MG can be considered a paraneoplastic disorder for extrathymic cancers.

METHODS

This is a retrospective analysis of the MG cohort for 23 years' time (January 2000 to May 2023), extracting cancer rates with clinical, electrophysiological, and biochemical cancer associations and the effect of chronic medications.

RESULTS

We identified 436 patients with MG and 3924 controls. The median age at symptom onset was 64 (5-93 years) for males and 54 (1-87 years) for females. MG symptoms at onset were recorded as ocular (60%), strictly bulbar (10%), or generalized (23%). Extrathymic cancer was found in 32% of MG patients. In 3%, thymic and extrathymic cancers co-occurred. Compared to controls, neurology (12.2%, 159/1308), internal medicine (24.4%, 319/1308), or rheumatology (12%, 157/1308), MG patients had significantly higher rates of extrathymic cancers (p < 0.001). Compared to the rheumatology group, the cancer relative risk of 2.97, CI = 2.5-3.4. Furthermore, the prevalence of extrathymic cancers was significantly increased within the paraneoplastic time window, defined as ±5 years from cancer diagnosis to myasthenia onset (p < 0.01).

CONCLUSION

MG was significantly associated with an increased risk of extrathymic cancers, particularly within the paraneoplastic time window. These findings suggest that MG might potentially behave as a paraneoplastic disorder.

Impact of SARS-CoV-2 infection on patients with myasthenia gravis: a retrospective study in a Chinese population

Background and purpose

Myasthenia gravis (MG) is characterized by fluctuating muscle weakness due to immune-mediated damage to acetylcholine receptors. Viral infections can exacerbate symptoms of muscle weakness, and the clinical status of patients with MG may influence the outcomes of such infections. Here, we identified factors of symptom exacerbation, severe SARS-CoV-2 infection, and pneumonia in patients with MG who are infected with SARS-CoV-2.

Methods

The clinical characteristics and outcomes of 341 MG patients infected with SARS-CoV-2 across multiple regions in China were determined.

Results

The median age of the patients was 49 years (range: 35-60 years) and the median disease duration was 4 years (range: 2-8 years). Among the patients, 67 (49.0%) were male and 174 (51.0%) were female. Multivariate analysis indicated that thymectomy [OR, 1.654 (95% CI, 1.036-2.643); p = 0.035], severe SARS-CoV-2 infection [OR, 4.275 (95% CI, 2.206-8.286); p < 0.001], and pyridostigmine bromide [OR, 1.955 (95% CI, 1.192-3.206); p = 0.008] were associated with exacerbation of MG symptoms in patients infected with SARS-CoV-2. Age was significantly associated with severe SARS-CoV-2 infection [OR, 1.023 (95% CI, 1.001-1.046); p = 0.008], while patients with cardiac/vascular comorbidities exhibited an increased likelihood of severe SARS-CoV-2 infection [OR, 3.276 (95% CI, 1.027-10.449); p = 0.045]. Likewise, steroid treatment [OR, 6.140 (95% CI, 2.335-16.140); p < 0.001] was associated with a significantly increased likelihood of severe SARS-CoV-2 infection compared with symptomatic treatment. Additionally, gender [OR, 0.323 (95% CI, 0.120-0.868); p = 0.025] and SARS-CoV-2 severity [OR, 6.067 (95% CI, 1.953-18.850); p = 0.002] were associated with the occurrence of pneumonia.

Conclusion

We identified factors that were associated with the exacerbation of MG symptoms in patients infected with SARS-CoV-2, including thymectomy, severe SARS-CoV-2 infection, and the use of pyridostigmine bromide. Due to the retrospective nature of the study, these findings should be interpreted as associations rather than predictive factors. However, the results confirm the established relationships between severe SARS-CoV-2 infection and age, cardiovascular comorbidities, and the use of steroid treatment, suggesting that these factors should be considered when managing MG patients during SARS-CoV-2 infection.

RANKL treatment restores thymic function and improves T cell-mediated immune responses in aged mice

Age-related thymic involution, leading to reduced T cell production, is one of the major causes of immunosenescence. This results in an increased susceptibility to cancers, infections, and autoimmunity and in reduced vaccine efficacy. Here, we identified that the receptor activator of nuclear factor κB (RANK)-RANK ligand (RANKL) axis in the thymus is altered during aging. Using a conditional transgenic mouse model, we demonstrated that endothelial cells depend on RANK signaling for their cellularity and functional maturation. Decreased RANKL availability during aging resulted in a decline in cellularity and function of both endothelial cells and thymic epithelial cells, contributing to thymic involution. We then found that, whereas RANKL neutralization in young mice mimicked thymic involution, exogenous RANKL treatment in aged mice restored thymic architecture as well as endothelial cell and epithelial cell abundance and functional properties. Consequently, RANKL improved T cell progenitor homing to the thymus and boosted T cell production. This cascade of events resulted in peripheral T cell renewal and effective antitumor and vaccine responses in aged mice. Furthermore, we conducted a proof-of-concept study that showed that RANKL stimulates endothelial cells and epithelial cells in human thymic organocultures. Overall, our findings suggest that targeting the RANK-RANKL axis through exogenous RANKL administration could represent a therapeutic strategy to rejuvenate thymic function and improve T cell immunity during aging.

Safety and Efficacy of Transsternal Core Biopsy of Anterior Mediastinal Masses

Background

The study evaluated the safety and adequacy of percutaneous transsternal anterior mediastinal core biopsy.

Methods

All percutaneous computed tomography-guided transsternal mediastinal 18-gauge core biopsies performed at 2 academic centers were retrospectively reviewed. Procedural, clinical, and pathology data were recorded.

Results

Sixteen patients underwent biopsies. Nine had preexisting cancer diagnoses. Biopsy was performed with general anesthesia (3), monitored anesthesia care (7), and moderate sedation (6). All patients were discharged the same day, except 1 patient, in whom a pneumothorax developed, necessitating chest tube placement. Of 16 biopsies, 15 (94%) yielded pathologic diagnoses, including thymoma (4), benign lesion (3), and 8 malignant neoplasms (3 lung cancer, 3 lymphoma, 1 thymic carcinoid tumor, 1 sarcoma). In most (14/16), ≥3 core specimens were obtained. In the nondiagnostic biopsy, only 1 core was obtained. Tissue was adequate in 4 of 6 cases for ancillary testing. Eight patients received diagnoses from core biopsy indicating observation or medical therapy, obviating the need for an operation.

Conclusions

Outpatient transsternal anterior mediastinal 18-gauge core biopsy is feasible, safe, and effective and may prevent unnecessary operations. Obtaining ≥3 cores may optimize diagnostic yield.

Engineering immune organoids to regenerate host immune system

Recent advances in immunotherapy have underscored the potential of harnessing the immune system to treat disorders associated with immune dysregulation, such as primary and secondary immunodeficiencies, cancer, transplantation rejection, and aging. Owing to the cellular and structural complexity and the dynamic nature of immune responses, engineering immune organoids that replicate the function and key features of their corresponding immune organs continues to be a formidable challenge. In this overview, we will discuss the recent progress in bioengineering organoids of key primary and secondary immune organs and tissues, focusing particularly on their contributions to the host's immune system in animal models and highlighting their potential roles in regenerative medicine.

Myasthenia Gravis Complicated by M-proteinemia and Demyelinating Neuropathy: A Report of Two Cases

Myasthenia gravis (MG) is characterized by weakness and rapid fatigue of voluntary muscles. Here, we present two cases of early-onset MG, complicated with M-proteinemia and demyelinating neuropathy. Case one was diagnosed with MG at age 29, received tacrolimus post-thymectomy, and developed M-proteinemia and demyelinating neuropathies at age 66 before being diagnosed with B-cell lymphoma. Case two was diagnosed with MG at age 21, received immunosuppressive drugs post-thymectomy, and was diagnosed with myelin-associated glycoprotein antibody-associated neuropathy at age 66. Demyelinating neuropathy with M-proteinuria should be considered when motor symptoms worsen in patients with early-onset MG who receive immunosuppressive drugs after thymectomy.

Pediatric brain tumor patients display altered immune activation and reduced lymphopoiesis at the onset of disease

Optimal immune function is crucial in preventing cancer development and growth and for the success of anti-cancer therapies. Here, we characterized the peripheral immunological status of 83 steroids-naïve pediatric patients with central nervous system neoplasia at the disease onset. Tumors were classified into low-grade gliomas (LGG), high-grade gliomas (HGG), medulloblastoma, and other tumors. We revealed that glioma patients showed an altered lymphocyte pool. T-cells of HGG patients shifted from naïve to effector memory phenotype. LGG patients exhibited T-cell central memory expansion and higher T-cell activation. Interestingly, HGG patients displayed reduced thymic function. Furthermore, LGG and HGG patients showed reduced activated B-cells and suboptimal B-cell formation. Our data demonstrate that glioma patients have reduced lymphopoiesis at the disease onset, which could contribute to the systemic lymphopenia characterizing these patients. This study offers novel insights into the immunological status of brain tumor patients which may help in designing more effective treatments.

Early-life thymectomy leads to an increase of granzyme-producing γδ T cells in children with congenital heart disease

Congenital heart disease (CHD) is the most common birth defect in newborns, often requiring cardiac surgery with concomitant thymectomy that is known to increase disease susceptibility later in life. Studies of γδ T cells, which are one of the dominant T cells in the early fetal human thymus, are rare. Here, we provide a comprehensive analysis of the γδ T cell compartment via flow cytometry and next-generation sequencing in children and infants with CHD, who underwent cardiac surgery shortly after birth. A perturbation of the γδ T cell repertoire is evident, and Vδ1 T cell numbers are reduced. However, those cells that are present, do retain cytotoxicity. In contrast, GZMA+CD28+CD161hi innate effector Vγ9Vδ2 T cells are found in higher proportions. TCR-seq identifies an increase in TRDJ3+ γδ T cell clones in children with CHD, but not in a confirmatory group of neonates prior to CHD surgery, which overall points to a persistence of fetal-derived effector γδ T cells in children with CHD.

Finding NEMO in the thymus

Rosain et al. (https://doi.org/10.1084/jem.20231152) describe the association between anti-type I interferon autoantibodies and severe viral infections in patients with incontinentia pigmenti and heterozygous loss-of-function NEMO variants, suggesting a role for canonical NF-κB signaling in immune tolerance. The mechanisms behind this selective autoimmunity remain unclear.

Exploring the interplay between cannabinoids and thymic functions

Cannabinoids, derived from the Cannabis sativa plant, have garnered increasing attention for their potential therapeutic applications in various diseases. The pharmacologically active compounds in Cannabis, such as delta-9-tetrahydrocannabinol and cannabidiol, exhibit diverse immunomodulatory properties. Although studies have explored the effects of cannabinoids on immune function, their specific interactions with the thymus, a primary immune organ critical for T-cell development and maturation, remain an intriguing area of investigation. As the thymus plays a fundamental role in shaping the immune repertoire, understanding the interplay between cannabinoids and thymic function may shed light on potential benefits or concerns associated with Cannabis-based therapies. This article aims to provide an overview of the current scientific knowledge regarding the impact of medicinal Cannabis on the thymus and its implications for disease treatment and immune health.

Spatial transcriptomics elucidates medulla niche supporting germinal center response in myasthenia gravis-associated thymoma

Myasthenia gravis (MG) is etiologically associated with thymus abnormalities, but its pathology in the thymus remains unclear. In this study, we attempt to narrow down the features associated with MG using spatial transcriptome analysis of thymoma and thymic hyperplasia samples. We find that the majority of thymomas are constituted by the cortical region. However, the small medullary region is enlarged in seropositive thymomas and contains polygenic enrichment and MG-specific germinal center structures. Neuromuscular medullary thymic epithelial cells, previously identified as MG-specific autoantigen-producing cells, are enriched in the cortico-medullary junction. The medulla is characterized by a specific chemokine pattern and immune cell composition, including migratory dendritic cells and effector regulatory T cells. Similar germinal center structures and immune microenvironments are also observed in the thymic hyperplasia medulla. This study shows that the medulla and junction areas are linked to MG pathology and provides insights into future MG research.

Abnormal Immune Profile in Individuals with Kabuki Syndrome

OBJECTIVE

To analyze the lymphocyte subsets in individuals with Kabuki syndrome for better characterizing the immunological phenotype of this rare congenital disorder.

METHODS

We characterized the immunological profile including B-, T- and natural killer-cell subsets in a series (N = 18) of individuals with Kabuki syndrome.

RESULTS

All 18 individuals underwent genetic analysis: 15 had a variant in KMT2D and 3 a variant in KDM6A. Eleven of the 18 individuals (61%) had recurrent infections and 9 (50%) respiratory infections. Three (17%) had autoimmune diseases. On immunological analysis, 6 (33%) had CD4 T-cell lymphopenia, which was preferentially associated with the KMT2D truncating variant (5/9 individuals). Eight of 18 individuals (44%) had a humoral deficiency and eight (44%) had B lymphopenia. We found abnormal distributions of T-cell subsets, especially a frequent decrease in recent thymic emigrant CD4 + naive T-cell count in 13/16 individuals (81%).

CONCLUSION

The immunological features of Kabuki syndrome showed variable immune disorders with CD4 + T-cell deficiency in one third of cases, which had not been previously reported. In particular, we found a reduction in recent thymic emigrant naïve CD4 + T-cell count in 13 of 16 individuals, representing a novel finding that had not previously been reported.

Associations between acute and chronic graft-versus-host disease

ABSTRACT

Chronic graft-versus-host disease (GVHD) is 1 of the major complications after allogeneic hematopoietic cell transplantation (allo-HCT). Although various risk factors for chronic GVHD have been reported, limited data are available regarding the impact of acute GVHD on chronic GVHD. We examined the association between acute and chronic GVHD using a Japanese registry data set. The landmark point was set at day 100 after allo-HCT, and patients who died or relapsed before the landmark point were excluded. In total, 14 618 and 6135 patients who underwent allo-HCT with bone marrow or peripheral blood (BM/PB) and with umbilical cord blood (UCB), respectively, were analyzed. In the BM/PB cohort, the risk for chronic GVHD that requires systemic steroids increased with each increase in acute GVHD grade from 0 to 2 (grade 0 vs 1 [hazard ratio (HR), 1.32; 95% confidence interval (CI), 1.19-1.46; P < .001]; grade 1 vs 2 [HR, 1.41; 95% CI, 1.28-1.56; P < .001]), but the risk was similar between acute GVHD grade 2 and grade 3 to 4 (HR, 1.02; 95% CI, 0.91-1.15; P = 1.0). These findings were confirmed in the UCB cohort. We further observed that the risk for severe chronic GVHD increased with each increment in the grade of acute GVHD, even between acute GVHD grade 2 and grade 3 to (grade 2 vs 3-4: HR, 1.70; 95% CI, 1.12-2.58; P = .025). In conclusion, the preceding profiles of acute GVHD should help to stratify the risk for chronic GVHD and its severity, which might be useful for the development of risk-adopted preemptive strategies for chronic GVHD.

The thymus road to a T cell: migration, selection, and atrophy

The thymus plays a pivotal role in generating a highly-diverse repertoire of T lymphocytes while preventing autoimmunity. Thymus seeding progenitors (TSPs) are a heterogeneous group of multipotent progenitors that migrate to the thymus via CCR7 and CCR9 receptors. While NOTCH guides thymus progenitors toward T cell fate, the absence or disruption of NOTCH signaling renders the thymus microenvironment permissive to other cell fates. Following T cell commitment, developing T cells undergo multiple selection checkpoints by engaging with the extracellular matrix, and interacting with thymic epithelial cells (TECs) and other immune subsets across the different compartments of the thymus. The different selection checkpoints assess the T cell receptor (TCR) performance, with failure resulting in either repurposing (agonist selection), or cell death. Additionally, environmental cues such as inflammation and endocrine signaling induce acute thymus atrophy, contributing to the demise of most developing T cells during thymic selection. We discuss the occurrence of acute thymus atrophy in response to systemic inflammation. The thymus demonstrates high plasticity, shaping inflammation by abrogating T cell development and undergoing profound structural changes, and facilitating regeneration and restoration of T cell development once inflammation is resolved. Despite the challenges, thymic selection ensures a highly diverse T cell repertoire capable of discerning between self and non-self antigens, ultimately egressing to secondary lymphoid organs where they complete their maturation and exert their functions.

Zoledronic acid for hip fracture during initial hospitalization

Inpatient zoledronic acid (IP-ZA) administered during the initial fracture hospitalization significantly improves the osteoporosis treatment rate. Clinical outcomes of IP-ZA after hip fracture remain uncertain. Here we report a cohort study that emulated a randomized controlled trial using real-world data and evaluated the risk of all-cause-mortality and radiologically confirmed subsequent new fractures among patients hospitalized for a hip fracture who had received IP-ZA as compared with propensity-matched controls. A total of 654 patients who had received IP-ZA and 6877 controls (for whom anti-osteoporosis treatment was indicated but no IP-ZA started during index hospitalization) were included in the study. The primary cohort comprised 652 IP-ZA patients (IP-ZA group) and 1926 matched controls (untreated group), with 71.7% female 92.1% White participants, with a mean age of 80.9 years. Cumulative all-cause mortality over the 24-month follow-up for the IP-ZA group was 12.3% and 20.7% for the untreated group (hazard ratio [HR], 0.62; 95% CI, 0.49-0.78, p < .001). A total of 585 (89.7%) patients in IP-ZA group received only a single dose of ZA during the 24 months, and the death rate of this single dose group was 13.3%, which was significantly lower than that of the untreated group (HR, 0.70; 95% CI, 0.55-0.89, p = .003). Rates of radiologically confirmed cumulative subsequent new vertebral fractures were 2.0% in the IP-ZA group and 5.4% in the untreated group (HR, 0.40; 95% CI, 0.22-0.71, p = .001). A similarly lower rate of new vertebral fractures was seen in the single dose subgroup (1.9% vs 5.4%; HR, 0.44; 95% 0.24-0.82, p = .008). IP-ZA, administered during the initial hospitalization for hip fracture, was associated with lower all-cause-mortality and risk of radiologically confirmed subsequent new vertebral fractures, and thus offers a mechanism to narrow the treatment gap in patients having sustained a hip fragility fracture.

Active thymus in adult with lung cancer: preliminary results from the Adult Thymic Project

Thymus is considered a non-functional remnant in adults, but some evidence suggest that it may harbor residual activity. Lung cancer patients represent the ideal model to study thymic residual activity, as their thymus can be easily harvested during surgery. This study was designed to confirm the presence of residual thymic activity both in adult mice (step 1) and in humans (step 2). In step 1, lung cancer was induced by activating k-ras mutation in a cohort of 20 young and adult mice. After killing, thymus and lungs were analyzed. Thymus was considered active when medullary was evident, cortico-medullary ratio was 50:50 or higher and adipose involution was present. In step 2, a cohort of 20 patients, undergoing surgery for lung cancer, had biopsy of pericardial fat pad, site of ectopic thymus. Thymus was considered present if Hassall's bodies were detected. In mice, active thymus was detected in a high proportion of cases, without significant difference between adult and young (70% vs 44.4% respectively). Two cases without evidence of lung tumor had a fully functional thymus. In humans, ectopic thymus was detected in the pericardial fat pad in 2 cases (10.5%), confirmed by immunohistochemistry. Signs of previous thymic activity were detected in 8 additional patients. Results confirmed thymus activity in animal models and humans with lung cancer, providing the rationale for future systematic mediastinal thymic biopsy. The comprehension of interactions between thymus, lymphocytes and tumor may open a new potentially targetable perspective in lung cancer.

Intravital two-photon microscopy of the native mouse thymus

The thymus, a key organ in the adaptive immune system, is sensitive to a variety of insults including cytotoxic preconditioning, which leads to atrophy, compression of the blood vascular system, and alterations in hemodynamics. Although the thymus has innate regenerative capabilities, the production of T cells relies on the trafficking of lymphoid progenitors from the bone marrow through the altered thymic blood vascular system. Our understanding of thymic blood vascular hemodynamics is limited due to technical challenges associated with accessing the native thymus in live mice. To overcome this challenge, we developed an intravital two-photon imaging method to visualize the native thymus in vivo and investigated functional changes to the vascular system following sublethal irradiation. We quantified blood flow velocity and shear rate in cortical blood vessels and identified a subtle but significant increase in vessel leakage and diameter ~24 hrs post-sublethal irradiation. Ex vivo whole organ imaging of optically cleared thymus lobes confirmed a disruption of the thymus vascular structure, resulting in an increase in blood vessel diameter and vessel area, and concurrent thymic atrophy. This novel two-photon intravital imaging method enables a new paradigm for directly investigating the thymic microenvironment in vivo.

Glucocorticoids impair T lymphopoiesis after myocardial infarction

The thymus, where T lymphocytes develop and mature, is sensitive to insults such as tissue ischemia or injury. The insults can cause thymic atrophy and compromise T-cell development, potentially impairing adaptive immunity. The objective of this study was to investigate whether myocardial infarction (MI) induces thymic injury to impair T lymphopoiesis and to uncover the underlying mechanisms. When compared with sham controls, MI mice at day 7 post-MI exhibited smaller thymus, lower cellularity, as well as less thymocytes at different developmental stages, indicative of T-lymphopoiesis impairment following MI. Accordingly, the spleen of MI mice has less T cells and recent thymic emigrants (RTEs), implying that the thymus of MI mice releases fewer mature thymocytes than sham controls. Interestingly, the secretory function of splenic T cells was not affected by MI. Further experiments showed that the reduction of thymocytes in MI mice was due to increased thymocyte apoptosis. Removal of adrenal glands by adrenalectomy (ADX) prevented MI-induced thymic injury and dysfunction, whereas corticosterone supplementation in ADX + MI mice reinduced thymic injury and dysfunction, indicating that glucocorticoids mediate thymic damage triggered by MI. Eosinophils play essential roles in thymic regeneration postirradiation, and eosinophil-deficient mice exhibit impaired thymic recovery after sublethal irradiation. Interestingly, the thymus was fully regenerated in both wild-type and eosinophil-deficient mice at day 14 post-MI, suggesting that eosinophils are not critical for thymus regeneration post-MI. In conclusion, our study demonstrates that MI-induced glucocorticoids trigger thymocyte apoptosis and impair T lymphopoiesis, resulting in less mature thymocyte release to the spleen.NEW & NOTEWORTHY The thymus is essential for maintaining whole body T-cell output. Thymic injury can adversely affect T lymphopoiesis and T-cell immune response. This study demonstrates that MI induces thymocyte apoptosis and compromises T lymphopoiesis, resulting in fewer releases of mature thymocytes to the spleen. This process is mediated by glucocorticoids secreted by adrenal glands. Therefore, targeting glucocorticoids represents a novel approach to attenuate post-MI thymic injury.

Association between thymus density loss and efficacy in non-small cell lung cancer patients treated with immune checkpoint inhibitors

Background

Although the thymus undergoes degeneration with the advancement of age, recent studies have continuously revealed that the thymus possesses the potential for regeneration and may reverse this aging trend. Furthermore, an increasing number of studies indicate an association between thymus function and immunotherapy. Considering that lung cancer patients typically undergo chest computed tomography (CT) scans during treatment, this provides convenient conditions for us to observe thymic remodeling through imaging data. Therefore, exploring the changes in the thymus on CT images is of great significance for understanding its relationship with the efficacy of immunotherapy in non-small cell lung cancer (NSCLC) patients. This study investigated the CT imaging characteristics of thymic density changes in patients with advanced NSCLC after immunotherapy. The primary objective was to determine whether changes in thymic density are predictors of response to immunotherapy in patients with NSCLC.

Methods

A total of 412 patients with advanced NSCLC who underwent immunotherapy were included. Thymic density measurements were taken initially and after immunotherapy, with the annualized change calculated. Comprehensive analysis, including disease progression, survival, and subgroup assessments, was conducted. The primary outcome was overall survival (OS), and the secondary outcomes were progression-free survival (PFS), objective response rate (ORR) and disease control rate (DCR).

Results

The annual change in density of the thymic region ranged from -108 to 108 HU after the initiation of ICIs. Patients were categorized into "loss" or "non-loss" groups (210 vs. 202) based on thymic density changes. Analysis of short-term progression of solid tumors revealed no statistically significant differences in ORR (P=0.55) and DCR (P=0.67) between the two groups. Throughout the entire follow-up period, 41 patients (19.5%) in the "loss" group and 64 patients (31.7%) in the "non-loss" group died. Thymic density reduction was not associated with PFS (P=0.08), but it was positively associated with increased OS (P=0.003). The results were consistent across subgroups.

Conclusions

Thymic density changes were observed in nearly all NSCLC patients undergoing immunotherapy, with decreased density associated with longer OS. These findings suggest a potential association between thymic density changes and immune efficacy in NSCLC immunotherapy.

Pneumonia, wheezing and asthma were more common in children after thymectomy due to open-heart surgery

AIM

This nationwide study evaluated the clinical impact that an early thymectomy, during congenital heart defect (CHD) surgery, had on the health of children and adolescents.

METHODS

The subjects were patients aged 1-15 years who had undergone CHD surgery at the University Children's Hospital, Helsinki, where all CHD surgery in Finland is carried out, from 2006 to 2018. The parents or the cases and population-based controls, matched for sex, age and hospital district, completed electronic questionnaires. We excluded those with low birth weights or a known immunodeficiency. Adjusted odds ratios (aOR) and 95% confidence intervals (CI) were calculated for prespecified outcomes.

RESULTS

We received responses relating to 260/450 (58%) cases and 1403/4500 (31%) controls and excluded 73 cases with persistent cardiac or respiratory complaints after surgery. The CHD group reported more recurrent hospitalisations due to infections (aOR 6.3, 95% CI 3.0-13) than the controls and more pneumonia episodes (aOR 3.5, 95% CI 2.1-5.6), asthma (aOR 2.5, 95% CI 1.5-4.1) and wheezing (aOR 2.1, 95% CI 1.5-2.9).

CONCLUSION

Hospitalisation due to infections, pneumonia, wheezing and asthma was more common in children after a thymectomy due to open-heart surgery than population-based controls, underlining the importance of immunological follow-ups.

Thymus in Cardiometabolic Impairments and Atherosclerosis: Not a Silent Player?

The thymus represents a primary organ of the immune system, harboring the generation and maturation of T lymphocytes. Starting from childhood, the thymus undergoes involution, being replaced with adipose tissue, and by an advanced age nearly all the thymus parenchyma is represented by adipocytes. This decline of thymic function is associated with compromised maturation and selection of T lymphocytes, which may directly impact the development of inflammation and induce various autoinflammatory disorders, including atherosclerosis. For a long time, thymus health in adults has been ignored. The process of adipogenesis in thymus and impact of thymic fat on cardiometabolism remains a mysterious process, with many issues being still unresolved. Meanwhile, thymus functional activity has a potential to be regulated, since islets of thymopoeisis remain in adults even at an advanced age. The present review describes the intricate process of thymic adipose involution, focusing on the issues of the thymus' role in the development of atherosclerosis and metabolic health, tightly interconnected with the state of vessels. We also review the recent information on the key molecular pathways and biologically active substances that may be targeted to manipulate both thymic function and atherosclerosis.

Does Surgical Removal of the Thymus Have Deleterious Consequences?

The role of immunosenescence, particularly the natural process of thymic involution during aging, is increasingly acknowledged as a factor contributing to the development of autoimmune diseases and cancer. Recently, a concern has been raised about deleterious consequences of the surgical removal of thymic tissue, including for patients who undergo thymectomy for myasthenia gravis (MG) or resection of a thymoma. This review adopts a multidisciplinary approach to scrutinize the evidence concerning the long-term risks of cancer and autoimmunity postthymectomy. We conclude that for patients with acetylcholine receptor antibody-positive MG and those diagnosed with thymoma, the removal of the thymus offers prominent benefits that well outweigh the potential risks. However, incidental removal of thymic tissue during other thoracic surgeries should be minimized whenever feasible.

Myasthenia gravis: the future is here

Myasthenia gravis (MG) stands as a prototypical antibody-mediated autoimmune disease: it is dependent on T cells and characterized by the presence of autoantibodies targeting proteins located on the postsynaptic surface of skeletal muscle, known as the neuromuscular junction. Patients with MG exhibit a spectrum of weakness, ranging from limited ocular muscle involvement to life-threatening respiratory failure. Recent decades have witnessed substantial progress in understanding the underlying pathophysiology, leading to the delineation of distinct subcategories within MG, including MG linked to AChR or MuSK antibodies as well as age-based distinction, thymoma-associated, and immune checkpoint inhibitor-induced MG. This heightened understanding has paved the way for the development of more precise and targeted therapeutic interventions. Notably, the FDA has recently approved therapeutic inhibitors of complement and the IgG receptor FcRn, a testament to our improved comprehension of autoantibody effector mechanisms in MG. In this Review, we delve into the various subgroups of MG, stratified by age, autoantibody type, and histology of the thymus with neoplasms. Furthermore, we explore both current and potential emerging therapeutic strategies, shedding light on the evolving landscape of MG treatment.

Premature thymic functional senescence is a hallmark of childhood acute lymphoblastic leukemia survivorship

Childhood acute lymphoblastic leukemia (cALL) survivors suffer early-onset chronic diseases classically associated with aging. Normal aging is accompanied by organ dysfunctions, including immunological ones. We hypothesize that thymic immunosenescence occurs in cALL survivors and that its severity may correlate with early-onset chronic diseases. The PETALE study is a cALL survivor cohort with an extensive cardiovascular and metabolic evaluation. The thymic immunosenescence biomarker, signal joint T-cell receptor excision circles (TREC), was evaluated and was highly correlated with age in healthy participants (n = 281) and cALL survivors (n = 248). We observed a systematic thymic immunoage accentuation in each cALL survivor compared to controls ranging from 5.9 to 88.3 years. The immunoage gain was independent of age at diagnosis and treatment modalities and was more severe for females. Thymic aging was associated with several pathophysiological parameters, was greater in survivors suffering from metabolic syndrome, but there was no significant association with global physical condition. The decrease in TREC was independent from blood cell counts, which were normal, suggesting a segmental aging of the thymic compartment. Indeed, increased plasmatic T cell regulatory cytokines IL-6, IL-7 and GM-CSF accompanied high immunoage gain. Our data reveal that cALL or its treatment trigger a rapid immunoage gain followed by further gradual thymic immunosenescence, similar to normal aging. This leads to an enduring shift in accentuated immunoage compared to chronological age. Thus, accentuated thymic immunosenescence is a hallmark of cALL survivorship and TREC levels could be useful immunosenescence biomarkers to help monitoring the health of cancer survivors.

Long-term follow-up of non-myasthenic patients with early-stage thymoma who underwent extended thymectomy or limited resection

BACKGROUD

The standard resection for early-stage thymoma is total thymectomy and complete tumour excision with or without myasthenia gravis but the optimal surgery mode for patients with early-stage non-myasthenic thymoma is debatable. This study analysed the oncological outcomes for non-myasthenic patients with early-stage thymoma treated by thymectomy or limited resection in the long term.

METHODS

Patients who had resections of thymic neoplasms at Taipei Veteran General Hospital, Taiwan between December 1997 and March 2013 were recruited, exclusive of those combined clinical evidence of myasthenia gravis were reviewed. A total of 113 patients were retrospectively reviewed with pathologic early stage (Masaoka stage I and II) thymoma who underwent limited resection or extended thymectomy to compare their long-term oncologic and surgical outcomes.

RESULTS

The median observation time was 134.1 months [interquartile range (IQR) 90.7-176.1 months]. In our cohort, 52 patients underwent extended thymectomy and 61 patients underwent limited resection. Shorter duration of surgery (p < 0.001) and length of stay (p = 0.006) were demonstrated in limited resection group. Six patients experienced thymoma recurrence, two of which had combined myasthenia gravis development after recurrence. There was no significant difference (p = 0.851) in freedom-from-recurrence, with similar 10-year freedom-from-recurrence rates between the limited resection group (96.2 %) and the thymectomy group (93.2 %). Tumour-related survival was also not significantly different between groups (p = 0.726).result CONCLUSION: Patients with early-stage non-myasthenic thymoma who underwent limited resection without complete excision of the thymus achieved similar oncologic outcomes during the long-term follow-up and better peri-operative results compared to those who underwent thymectomy.

Rebuilding and rebooting immunity with stem cells

Advances in modern medicine have enabled a rapid increase in lifespan and, consequently, have highlighted the immune system as a key driver of age-related disease. Immune regeneration therapies present exciting strategies to address age-related diseases by rebooting the host's primary lymphoid tissues or rebuilding the immune system directly via biomaterials or artificial tissue. Here, we identify important, unanswered questions regarding the safety and feasibility of these therapies. Further, we identify key design parameters that should be primary considerations guiding technology design, including timing of application, interaction with the host immune system, and functional characterization of the target patient population.