CD45: a critical regulator of signaling thresholds in immune cells

Galectin-8 inhibition and functions in immune response and tumor biology

Galectins are among organisms' most abundantly expressed lectins (carbohydrate-binding proteins) that specifically bind β-galactosides. They act not only outside the cell, where they bind to extracellular matrix glycans, but also inside the cell, where they have a significant impact on signaling pathways. Galectin-8 is a galectin family protein encoded by the LGALS8 gene. Its role is evident in both T- and B-cell immunity and in the innate immune response, where it acts directly on dendritic cells and induces some pro-inflammatory cytokines. Galectin-8 also plays an important role in the defense against bacterial and viral infections. It is known to promote antibacterial autophagy by recognizing and binding glycans present on the vacuolar membrane, thus acting as a danger receptor. The most important role of galectin-8 is the regulation of cancer growth, metastasis, tumor progression, and tumor cell survival. Importantly, the expression of galectins is typically higher in tumor tissues than in noncancerous tissues. In this review article, we focus on galectin-8 and its function in immune response, microbial infections, and cancer. Given all of these functions of galectin-8, we emphasize the importance of developing new and selective galectin-8 inhibitors and report the current status of their development.

Characterization of non-epithelial cells embedded within the vocal fold epithelial barrier

The vocal folds vibrate to produce voice, undergoing significant stress due to contact and shearing force. The epithelium operates as the primary protective layer of the tissue against stress and vibratory damage, as well as to provide a barrier against foreign organisms and toxins. Within the vocal fold epithelium, non-epithelial cells were identified that may interrupt the epithelium and compromise the epithelial barrier's protective function. Human vocal fold samples with a variety of pathologies were compared to normal vocal folds. Analysis included the number of cells in the epithelium and epithelial thickness. Vocal fold sections from 10 human tissue samples were assessed via H&E staining and immunofluorescent co-labeling. Three cell populations (vimentin expressing, CD-45 expressing, and cells expressing both) were identified within the epithelium. Statistical analysis revealed that the abnormal samples had a significantly greater number of vimentin-positive cells/area within the epithelium compared to the normal samples. Additionally, normal tissue samples had a significantly greater epithelial depth, suggesting a more robust epithelial barrier compared to tissue with pathology. Knowledge of the function of these cells could lead to a better understanding of how the local immune environment near and within vocal fold epithelium changes in the presence of different pathologies.

Inhibition of B cell receptor signaling induced by the human adenovirus species D E3/49K protein

Introduction

The early transcription unit 3 (E3) of human adenoviruses (HAdVs) encodes several immunoevasins, including the E3/49K protein, which is unique for species D of HAdVs. It is expressed as surface transmembrane protein and shed. E3/49K of HAdV-D64 binds to the protein tyrosine phosphatase surface receptor CD45, thereby modulating activation of T and NK cells.

Methods

Considering that E3/49K represents the most polymorphic viral protein among species D HAdVs, we demonstrate here that all tested E3/49K orthologs bind to the immunologically important regulator CD45. Thus, this feature is conserved regardless of the pathological associations of the respective HAdV types.

Results

It appeared that modulation of CD45 is a unique property restricted to HAdVs of species D. Moreover, E3/49K treatment inhibited B cell receptor (BCR) signaling and impaired BCR signal phenotypes. The latter were highly comparable to B cells having defects in the expression of CD45, suggesting E3/49K as a potential tool to investigate CD45 specific functions.

Conclusion

We identified B cells as new direct target of E3/49K-mediated immune modulation, representing a novel viral immunosubversive mechanism.

Expression of CD45 in non-hematopoietic cells: implications in regenerative medicine and disease management

CD45 plays a crucial role in the regulation of hematopoiesis. However, a comprehensive understanding of its role in non-hematopoietic cells is lacking. Several tissue precursors express CD45, indicating its crucial role in tissue regeneration. These precursors would fall prey to the recent therapies involving CD45 as a target. CD45+ double-positive tumor cells contribute to cancer progression, but whether CD45 is involved in the process needs to be investigated. Recently, we showed that aging induces CD45 expression in mesenchymal stromal cells and affects their differentiation potential. In this review, we, for the first time, unravel the important implications of the expression of CD45 in non-hematopoietic cells and provide novel insights into its potential therapeutic target in regenerative medicine and disease management.

An exploration of the causal relationship between 731 immunophenotypes and osteoporosis: a bidirectional Mendelian randomized study

Background

There are complex interactions between osteoporosis and the immune system, and it has become possible to explore their causal relationship based on Mendelian randomization methods.

Methods

Utilizing openly accessible genetic data and employing Mendelian randomization analysis, we investigated the potential causal connection between 731 immune cell traits and the risk of developing osteoporosis.

Results

Ten immune cell phenotypes were osteoporosis protective factors and three immune cell phenotypes were osteoporosis risk factors. Specifically, the odds ratio (OR) of IgD+ CD24+ %B cell (B cell panel) risk on Osteoporosis was estimated to be 0.9986 (95% CI = 0.9978~0.9996, P<0.01). The OR of CD24+ CD27+ %B cell (B cell panel) risk on Osteoporosis was estimated to be 0.9991 (95% CI = 0.9984~0.9998, P = 0.021). The OR of CD33- HLA DR+AC (Myeloid cell panel) risk on Osteoporosis was estimated to be 0.9996 (95% CI = 0.9993~0.9999, P = 0.038). The OR of EM CD8br %CD8br (Maturation stages of T cell panel) risk on Osteoporosis was estimated to be 1.0004 (95% CI = 1.0000~1.0008, P = 0.045). The OR of CD25 on IgD+ (B cell panel) risk on Osteoporosis was estimated to be 0.9995 (95% CI = 0.9991~0.9999, P = 0.024). The OR of CD25 on CD39+ activated Treg+ (Treg panel) risk on Osteoporosis was estimated to be 1.001 (95% CI = 1.0001~1.0019, P = 0.038). The OR of CCR2 on CD62L+ myeloid DC (cDC panel) risk on Osteoporosis was estimated to be 0.9992 (95% CI = 0.9984~0.9999, P = 0.048). The OR of CCR2 on CD62L+ plasmacytoid DC (cDC panel) risk on Osteoporosis was estimated to be 0.9993 (95% CI = 0.9987~0.9999, P = 0.035). The OR of CD45 on CD33dim HLA DR+ CD11b- (Myeloid cell panel) risk on Osteoporosis was estimated to be 0.9988 (95% CI = 0.9977~0.9998, P = 0.031). The OR of CD45 on Mo MDSC (Myeloid cell panel) risk on Osteoporosis was estimated to be 0.9992 (95% CI = 0.9985~0.9998, P = 0.017). The OR of SSC-A on B cell (TBNK panel) risk on Osteoporosis was estimated to be 0.9986 (95% CI = 0.9972~0.9999, P = 0.042). The OR of CD11c on CD62L+ myeloid DC (cDC panel) risk on Osteoporosis was estimated to be 0.9987 (95% CI = 0.9978~0.9996, P<0.01). The OR of HLA DR on DC (cDC panel) risk on Osteoporosis was estimated to be 1.0007 (95% CI = 1.0002~1.0011, P<0.01). No causal effect of osteoporosis on immune cells was observed.

Conclusions

Our study identified 13 unreported immune phenotypes that are causally related to osteoporosis, providing a theoretical basis for the bone immunology doctrine.

Evaluation of immunophenotypic alterations of peripheral blood lymphocytes and their sub-sets in uncomplicated P. Falciparum infection

BACKGROUND

Malaria is a life-threatening parasitic disease typically transmitted through the bite of an infected Anopheles mosquito. There is ample evidence showing the potential of malaria infection to affect the counts of lymphocyte subpopulations in the peripheral blood, but the extent of alteration might not be consistent in all geographical locations, due to several local factors. Although Ghana is among the malaria-endemic countries, there is currently no available data on the level of alterations that occur in the counts of lymphocyte subpopulations during P. falciparum malaria infection among adults.

AIM

The study was to determine the immunophenotypic alterations in the level of peripheral blood lymphocytes and their subsets in adults with uncomplicated P. falciparum malaria infection and apparently healthy participants.

METHODS

The study was a cross-sectional comparative study conducted in two municipalities of the Volta region of Ghana. Blood samples were collected from study participants and taken through serology (P. falciparum/Pan Rapid Diagnostic Kits), microscopy (Thick and thin blood films) and Haematological (Flow cytometric and Full blood count) analysis.

RESULTS

A total of 414 participants, comprising 214 patients with malaria and 200 apparently healthy individuals (controls) were recruited into this study. Parasite density of the malaria patients ranged from 75/µL to 84,364/µL, with a mean of 3,520/µL. It was also observed that the total lymphocytes slightly decreased in the P. falciparum-infected individuals (Mean ± SD: 2.08 ± 4.93 × 109/L) compared to the control group (Mean ± SD: 2.47 ± 0.80 × 109/L). Again, there was a significant moderate positive correlation between parasite density and haematocrit levels (r = 0.321, p < 0.001). Apart from CD45 + T-cells, more people in the control group had normal values for the lymphocyte subsets measured compared to the malaria patients.

CONCLUSIONS

From the results obtained, there was high parasite density among the malaria patients suggestive of high intensity of infection in the case group. The malaria patients again showed considerable haematological alterations in lymphocyte sub-sets and the parasite density appeared to be strongly associated with CD4 + T-cell reduction. Also, the parasite density significantly associated with decreasing haematocrit levels. This indicates that lymphocyte subset enumeration can be used to effectively support malaria diagnosis.

Identification of potential hub genes and biological mechanism in rheumatoid arthritis and non-small cell lung cancer via integrated bioinformatics analysis

BACKGROUND

Although there is evidence of the association between RA and NSCLC, little is known about their interaction mechanisms. The aim of this study is to identify potential hub genes and biological mechanism in RA and NSCLC via integrated bioinformatics analysis.

METHODS

The gene expression datasets of RA and NSCLC were downloaded to discover and validate hub genes. After identifying DEGs, we performed enrichment analysis, PPI network construction and module analysis, selection and validation of hub genes. Moreover, we selected the hub gene PTPRC for expression and prognosis analysis, immune analysis, mutation and methylation analysis in NSCLC. Finally, we performed real-time PCR, colony formation assay, wound healing assay, transwell invasion assay, sphere formation assay and western blotting to validate the role of PTPRC in A549 cells.

RESULTS

We obtained 320 DEGs for subsequent analysis. Enrichment results showed that the DEGs were mainly involved in Th1, Th2 and Th17 cell differentiation. In addition, four hub genes, BIRC5, PTPRC, PLEK, and FYN, were identified after selection and validation. These hub genes were subsequently shown to be closely associated with immune cells and related pathways. In NSCLC, PTPRC was downregulated, positively correlated with immune infiltration and immune cells. Experiments showed that PTPRC could promote the proliferation, migration and invasion, and the ability to form spheroids of A549 cells. In addition, PTPRC could regulate the increased expression of CD45, β-catenin, c-Myc and LEF1 proteins.

CONCLUSIONS

This study explored the hub genes and related mechanisms of RA and NSCLC, demonstrated the central role of the inflammatory response and the adaptive immune system, and identified PTPRC as an immune-related biomarker and potential therapeutic target for RA and NSCLC patients. In addition, PTPRC can significantly promote the proliferation, migration and invasion of A549 cells, and its mechanism may be to promote the EMT process by regulating the Wnt signaling pathway and promote cell stemness, which in turn has a promoting effect on A549 cells.

3-Fucosyllactose-mediated modulation of immune response against virus infection

Viral pathogens, particularly influenza and SARS-CoV-2, pose a significant global health challenge. Given the immunomodulatory properties of human milk oligosaccharides, in particular 2'-fucosyllactose and 3-fucosyllactose (3-FL), we investigated their dietary supplementation effects on antiviral responses in mouse models. This study revealed distinct immune modulations induced by 3-FL. RNA-sequencing data showed that 3-FL increased the expression of interferon receptors, such as Interferon Alpha and Beta Receptor (IFNAR) and Interferon Gamma Receptor (IFNGR), while simultaneously downregulating interferons and interferon-stimulated genes, an effect not observed with 2'-fucosyllactose supplementation. Such modulation enhanced antiviral responses in both cell culture and animal models while attenuating pre-emptive inflammatory responses. Nitric oxide concentrations in 3-FL-supplemented A549 cells and mouse lung tissues were elevated exclusively upon infection, reaching 5.8- and 1.9-fold increases over control groups, respectively. In addition, 3-FL promoted leukocyte infiltration into the site of infection upon viral challenge. 3-FL supplementation provided protective efficacy against lethal influenza challenge in mice. The demonstrated antiviral efficacy spanned multiple influenza strains and extended to SARS-CoV-2. In conclusion, 3-FL is a unique immunomodulator that helps protect the host from viral infection while suppressing inflammation prior to infection.

Assessing the causal relationship between circulating immune cells and abdominal aortic aneurysm by bi-directional Mendelian randomization analysis

Although there is an association between abdominal aortic aneurysm (AAA) and circulating immune cell phenotypes, the exact causal relationship remains unclear. This study aimed to explore the causal relationships between immune cell phenotypes and AAA risk using a bidirectional two-sample Mendelian randomization approach. Data from genome-wide association studies pertaining to 731 immune cell traits and AAA were systematically analyzed. Using strict selection criteria, we identified 339 immune traits that are associated with at least 3 single nucleotide polymorphisms. A comprehensive MR analysis was conducted using several methods including Inverse Variance Weighted, Weighted Median Estimator, MR-Egger regression, Weighted Mode, and Simple Median methods. CD24 on switched memory cells (OR = 0.922, 95% CI 0.914-0.929, P = 2.62e-79) at the median fluorescence intensities level, and SSC-A on HLA-DR + natural killer cells (OR = 0.873, 95% CI 0.861-0.885, P = 8.96e-81) at the morphological parameter level, exhibited the strongest causal associations with AAA. In the reverse analysis, no significant causal effects of AAA on immune traits were found. The study elucidates the causal involvement of multiple circulating immune cell phenotypes in AAA development, signifying their potential as diagnostic markers or therapeutic targets. These identified immune traits may be crucial in modulating AAA-related inflammatory pathways.

Characterization of perivascular alveolar epithelial stem cells and their niche in lung homeostasis and cancer

Lung alveolar structure and function are maintained by subsets of alveolar type II stem cells (AT2s), but there is a need for characterization of these subsets and their associated niches. Here, we report a CD44high subpopulation of AT2s characterized by increased expression of genes that regulate immune signaling even during steady-state homeostasis. Disruption of one of these immune regulatory transcription factor STAT1 impaired the stem cell function of AT2s. CD44high cells were preferentially located near macro- blood vessels and a supportive niche constituted by LYVE1+ endothelial cells, adventitial fibroblasts, and accumulated hyaluronan. In this microenvironment, CD44high AT2 cells were more responsive to transformation by KRAS than general AT2 cells. Moreover, after bacterial lung injury, there was a significant increase of CD44high AT2s and niche components distributed throughout the lung parenchyma. Taken together, CD44high AT2 cells and their perivascular niche regulate tissue homeostasis and tumor formation.

Expanding the horizons of targeted protein degradation: A non-small molecule perspective

Targeted protein degradation (TPD) represented by proteolysis targeting chimeras (PROTACs) marks a significant stride in drug discovery. A plethora of innovative technologies inspired by PROTAC have not only revolutionized the landscape of TPD but have the potential to unlock functionalities beyond degradation. Non-small-molecule-based approaches play an irreplaceable role in this field. A wide variety of agents spanning a broad chemical spectrum, including peptides, nucleic acids, antibodies, and even vaccines, which not only prove instrumental in overcoming the constraints of conventional small molecule entities but also provided rapidly renewing paradigms. Herein we summarize the burgeoning non-small molecule technological platforms inspired by PROTACs, including three major trajectories, to provide insights for the design strategies based on novel paradigms.

Genetically predicted N-methylhydroxyproline levels mediate the association between naive CD8+ T cells and allergic rhinitis: a mediation Mendelian randomization study

Background

Allergic rhinitis (AR), a prevalent chronic inflammatory condition triggered by immunoglobulin E (IgE), involves pivotal roles of immune and metabolic factors in its onset and progression. However, the intricacies and uncertainties in clinical research render current investigations into their interplay somewhat inadequate.

Objective

To elucidate the causal relationships between immune cells, metabolites, and AR, we conducted a mediation Mendelian randomization (MR) analysis.

Methods

Leveraging comprehensive publicly accessible summary-level data from genome-wide association studies (GWAS), this study employed the two-sample MR research method to investigate causal relationships among 731 immune cell phenotypes, 1400 metabolite levels, and AR. Additionally, employing the mediation MR approach, the study analyzed potential mediated effect of metabolites in the relationships between immune cells and AR. Various sensitivity analysis methods were systematically employed to ensure the robustness of the results.

Results

Following false discovery rate (FDR) correction, we identified three immune cell phenotypes as protective factors for AR: Naive CD8br %CD8br (odds ratio (OR): 0.978, 95% CI = 0.966-0.990, P = 4.5×10-4), CD3 on CD39+ activated Treg (OR: 0.947, 95% CI = 0.923-0.972, P = 3×10-5), HVEM on CD45RA- CD4+ (OR: 0.967, 95% CI = 0.948-0.986, P = 4×10-5). Additionally, three metabolite levels were identified as risk factors for AR: N-methylhydroxyproline levels (OR: 1.219, 95% CI = 1.104-1.346, P = 9×10-5), N-acetylneuraminate levels (OR: 1.133, 95% CI = 1.061-1.211, P = 1.7×10-4), 1-stearoyl-2-arachidonoyl-gpc (18:0/20:4) levels (OR: 1.058, 95% CI = 1.029-1.087, P = 5×10-5). Mediation MR analysis indicated a causal relationship between Naive CD8br %CD8br and N-methylhydroxyproline levels, acting as a protective factor (OR: 0.971, 95% CI = 0.950-0.992, P = 8.31×10-3). The mediated effect was -0.00574, accounting for 26.1% of the total effect, with a direct effect of -0.01626. Naive CD8+ T cells exert a protective effect on AR by reducing N-methylhydroxyproline levels.

Conclusion

Our study, delving into genetic information, has substantiated the intricate connection between immune cell phenotypes and metabolite levels with AR. This reveals a potential pathway to prevent the onset of AR, providing guiding directions for future clinical investigations.

Alloengraftment without significant toxicity or GVHD in CD45 antibody-drug conjugate-conditioned Fanconi anemia mice

ABSTRACT

Fanconi anemia (FA) is an inherited DNA repair disorder characterized by bone marrow (BM) failure, developmental abnormalities, myelodysplasia, leukemia, and solid tumor predisposition. Allogeneic hematopoietic stem cell transplantation (allo-HSCT), a mainstay treatment, is limited by conditioning regimen-related toxicity and graft-versus-host disease (GVHD). Antibody-drug conjugates (ADCs) targeting hematopoietic stem cells (HSCs) can open marrow niches permitting donor stem cell alloengraftment. Here, we report that single dose anti-mouse CD45-targeted ADC (CD45-ADC) facilitated stable, multilineage chimerism in 3 distinct FA mouse models representing 90% of FA complementation groups. CD45-ADC profoundly depleted host stem cell enriched Lineage-Sca1+cKit+ cells within 48 hours. Fanca-/- recipients of minor-mismatched BM and single dose CD45-ADC had peripheral blood (PB) mean donor chimerism >90%; donor HSCs alloengraftment was verified in secondary recipients. In Fancc-/- and Fancg-/- recipients of fully allogeneic grafts, PB mean donor chimerism was 60% to 80% and 70% to 80%, respectively. The mean percent donor chimerism in BM and spleen mirrored PB results. CD45-ADC-conditioned mice did not have clinical toxicity. A transient <2.5-fold increase in hepatocellular enzymes and mild-to-moderate histopathological changes were seen. Under GVHD allo-HSCT conditions, wild-type and Fanca-/- recipients of CD45-ADC had markedly reduced GVHD lethality compared with lethal irradiation. Moreover, single dose anti-human CD45-ADC given to rhesus macaque nonhuman primates on days -6 or -10 was at least as myeloablative as lethal irradiation. These data suggest that CD45-ADC can potently promote donor alloengraftment and hematopoiesis without significant toxicity or severe GVHD, as seen with lethal irradiation, providing strong support for clinical trial considerations in highly vulnerable patients with FA.

Dynamics of CD44+ bovine nucleus pulposus cells with inflammation

Intervertebral Disc (IVD) degeneration has been associated with a chronic inflammatory response, but knowledge on the contribution of distinct IVD cells, namely CD44, to the progression of IVD degeneration remains elusive. Here, bovine nucleus pulposus (NP) CD44 cells were sorted and compared by gene expression and proteomics with the negative counterpart. NP cells were then stimulated with IL-1b (10 ng/ml) and dynamics of CD44 gene and protein expression was analyzed upon pro-inflammatory treatment. The results emphasize that CD44 has a multidimensional functional role in IVD metabolism, ECM synthesis and production of neuropermissive factors. CD44 widespread expression in NP was partially associated with CD14 and CD45, resulting in the identification of distinct cell subsets. In conclusion, this study points out CD44 and CD44-based cell subsets as relevant targets in the modulation of the IVD pro-inflammatory/degenerative cascade.

Exploring the immunological landscape of osteomyelitis through mendelian randomization analysis

Background

Osteomyelitis is a severe bone marrow infection, whose pathogenesis is not yet fully understood. This study aims to explore the causal relationship between immune cell characteristics and osteomyelitis, hoping to provide new insights for the prevention and treatment of osteomyelitis.

Methods

Based on two independent samples, this study employed a two-sample Mendelian randomization (MR) analysis to assess the causal relationship between 731 immune cell characteristics (divided into seven groups) and osteomyelitis. Genetic variants were used as proxies for risk factors to ensure that the selected instrumental variables meet the three key assumptions of MR analysis. Genome-Wide Association Studies (GWAS) data for immune characteristics were obtained from the public GWAS catalog, while data for osteomyelitis was sourced from the FinnGen.

Results

At a significance level of 0.05, 21 immune phenotypes were identified as having a causal relationship with osteomyelitis development. In the B cell group, phenotypes such as Memory B cell % B cell (percentage of memory B cells within the total B cell population, % finger cell ratio), CD20- %B cell (percentage of B cells that do not express the CD20 marker on their surface), and Memory B cell % lymphocyte showed a positive causal relationship with osteomyelitis, while Naive-mature B cell %B cell and IgD-CD38-absolute cell counts (AC) phenotypes showed a negative causal relationship. In addition, specific immune phenotypes in the conventional dendritic cells (cDCs) group, Myeloid cell group, TBNK (T cells, B cells, natural killer cells) cell group, T cell maturation stage, and Treg cell group also showed significant associations with osteomyelitis. Through reverse MR analysis, it was found that osteomyelitis had no significant causal impact on these immune phenotypes, suggesting that the occurrence of osteomyelitis may not affect these immune cell phenotypes.

Conclusion

To our knowledge, this is the first study to shed light on the causal relationship between specific immune cell characteristics and the development of osteomyelitis, thereby providing a new perspective to understand the immune mechanism of osteomyelitis. These findings are significant for formulating targeted prevention and treatment strategies, and hold promise to improve the treatment outcomes for patients with osteomyelitis.

Circulating tumor cells shielded with extracellular vesicle-derived CD45 evade T cell attack to enable metastasis

Circulating tumor cells (CTCs) are precursors of distant metastasis in a subset of cancer patients. A better understanding of CTCs heterogeneity and how these CTCs survive during hematogenous dissemination could lay the foundation for therapeutic prevention of cancer metastasis. It remains elusive how CTCs evade immune surveillance and elimination by immune cells. In this study, we unequivocally identified a subpopulation of CTCs shielded with extracellular vesicle (EVs)-derived CD45 (termed as CD45+ CTCs) that resisted T cell attack. A higher percentage of CD45+ CTCs was found to be closely correlated with higher incidence of metastasis and worse prognosis in cancer patients. Moreover, CD45+ tumor cells orchestrated an immunosuppressive milieu and CD45+ CTCs exhibited remarkably stronger metastatic potential than CD45- CTCs in vivo. Mechanistically, CD45 expressing on tumor surfaces was shown to form intercellular CD45-CD45 homophilic interactions with CD45 on T cells, thereby preventing CD45 exclusion from TCR-pMHC synapse and leading to diminished TCR signaling transduction and suppressed immune response. Together, these results pointed to an underappreciated capability of EVs-derived CD45-dressed CTCs in immune evasion and metastasis, providing a rationale for targeting EVs-derived CD45 internalization by CTCs to prevent cancer metastasis.

Cellular and molecular signaling towards T cell immunological self-tolerance

The binding of a cognate antigen to T cell receptor (TCR) complex triggers a series of intracellular events controlling T cell activation, proliferation, and differentiation. Upon TCR engagement, different negative regulatory feedback mechanisms are rapidly activated to counterbalance T cell activation, thus preventing excessive signal propagation and promoting the induction of immunological self-tolerance. Both positive and negative regulatory processes are tightly controlled to ensure the effective elimination of foreign antigens while limiting surrounding tissue damage and autoimmunity. In this context, signals deriving from co-stimulatory molecules (i.e., CD80, CD86), co-inhibitory receptors (PD-1, CTLA-4), the tyrosine phosphatase CD45 and cytokines such as IL-2 synergize with TCR-derived signals to guide T cell fate and differentiation. The balance of these mechanisms is also crucial for the generation of CD4+ Foxp3+ regulatory T cells, a cellular subset involved in the control of immunological self-tolerance. This review provides an overview of the most relevant pathways induced by TCR activation combined with those derived from co-stimulatory and co-inhibitory molecules implicated in the cell-intrinsic modulation of T cell activation. In addition to the latter, we dissected mechanisms responsible for T cell-mediated suppression of immune cell activation through regulatory T cell generation, homeostasis, and effector functions. We also discuss how imbalanced signaling derived from TCR and accessory molecules can contribute to autoimmune disease pathogenesis.

Causal relationship between immune cells and prostate cancer: a Mendelian randomization study

Introduction

Despite the abundance of research indicating the participation of immune cells in prostate cancer development, establishing a definitive cause-and-effect relationship has proven to be a difficult undertaking.

Methods

This study employs Mendelian randomization (MR), leveraging genetic variables related to immune cells from publicly available genome-wide association studies (GWAS), to investigate this association. The primary analytical method used in this study is inverse variance weighting (IVW) analysis. Comprehensive sensitivity analyses were conducted to assess the heterogeneity and horizontal pleiotropy of the results.

Results

The study identifies four immune cell traits as causally contributing to prostate cancer risk, including CD127- CD8+ T cell %CD8+ T cell (OR = 1.0042, 95%CI:1.0011-1.0073, p = 0.0077), CD45RA on CD39+ resting CD4 regulatory T cell (OR = 1.0029, 95%CI:1.0008-1.0050, p = 0.0065), CD62L- Dendritic Cell Absolute Count (OR = 1.0016; 95%CI:1.0005-1.0026; p = 0.0039), CX3CR1 on CD14+ CD16- monocyte (OR = 1.0024, 95%CI:1.0007-1.0040, p = 0.0060). Additionally, two immune cell traits are identified as causally protective factors: CD4 on monocyte (OR = 0.9975, 95%CI:0.9958-0.9992, p = 0.0047), FSC-A on plasmacytoid Dendritic Cell (OR = 0.9983, 95%CI:0.9970-0.9995, p = 0.0070). Sensitivity analyses indicated no horizontal pleiotropy.

Discussion

Our MR study provide evidence for a causal relationship between immune cells and prostate cancer, holding implications for clinical diagnosis and treatment.

Proteogenomic analysis of enriched HGSOC tumor epithelium identifies prognostic signatures and therapeutic vulnerabilities

We performed a deep proteogenomic analysis of bulk tumor and laser microdissection enriched tumor cell populations from high-grade serous ovarian cancer (HGSOC) tissue specimens spanning a broad spectrum of purity. We identified patients with longer progression-free survival had increased immune-related signatures and validated proteins correlating with tumor-infiltrating lymphocytes in 65 tumors from an independent cohort of HGSOC patients, as well as with overall survival in an additional 126 HGSOC patient cohort. We identified that homologous recombination deficient (HRD) tumors are enriched in pathways associated with metabolism and oxidative phosphorylation that we validated in independent patient cohorts. We further identified that polycomb complex protein BMI-1 is elevated in HR proficient (HRP) tumors, that elevated BMI-1 correlates with poor overall survival in HRP but not HRD HGSOC patients, and that HRP HGSOC cells are uniquely sensitive to BMI-1 inhibition.

Parotid glands have a dysregulated immune response following radiation therapy

Head and neck cancer treatment often consists of surgical resection of the tumor followed by ionizing radiation (IR), which can damage surrounding tissues and cause adverse side effects. The underlying mechanisms of radiation-induced salivary gland dysfunction are not fully understood, and treatment options are scarce and ineffective. The wound healing process is a necessary response to tissue injury, and broadly consists of inflammatory, proliferative, and redifferentiation phases with immune cells playing key roles in all three phases. In this study, select immune cells were phenotyped and quantified, and certain cytokine and chemokine concentrations were measured in mouse parotid glands after IR. Further, we used a model where glandular function is restored to assess the immune phenotype in a regenerative response. These data suggest that irradiated parotid tissue does not progress through a typical inflammatory response observed in wounds that heal. Specifically, total immune cells (CD45+) decrease at days 2 and 5 following IR, macrophages (F4/80+CD11b+) decrease at day 2 and 5 and increase at day 30, while neutrophils (Ly6G+CD11b+) significantly increase at day 30 following IR. Additionally, radiation treatment reduces CD3- cells at all time points, significantly increases CD3+/CD4+CD8+ double positive cells, and significantly reduces CD3+/CD4-CD8- double negative cells at day 30 after IR. Previous data indicate that post-IR treatment with IGF-1 restores salivary gland function at day 30, and IGF-1 injections attenuate the increase in macrophages, neutrophils, and CD4+CD8+ T cells observed at day 30 following IR. Taken together, these data indicate that parotid salivary tissue exhibits a dysregulated immune response following radiation treatment which may contribute to chronic loss of function phenotype in head and neck cancer survivors.

Heterogeneity of hepatocyte dynamics restores liver architecture after chemical, physical or viral damage

Midlobular hepatocytes are proposed to be the most plastic hepatic cell, providing a reservoir for hepatocyte proliferation during homeostasis and regeneration. However, other mechanisms beyond hyperplasia have been little explored and the contribution of other hepatocyte subpopulations to regeneration has been controversial. Thus, re-examining hepatocyte dynamics during regeneration is critical for cell therapy and treatment of liver diseases. Using a mouse model of hepatocyte- and non-hepatocyte- multicolor lineage tracing, we demonstrate that midlobular hepatocytes also undergo hypertrophy in response to chemical, physical, and viral insults. Our study shows that this subpopulation also combats liver impairment after infection with coronavirus. Furthermore, we demonstrate that pericentral hepatocytes also expand in number and size during the repair process and Galectin-9-CD44 pathway may be critical for driving these processes. Notably, we also identified that transdifferentiation and cell fusion during regeneration after severe injury contribute to recover hepatic function.

Cytotoxic CD8+ Temra cells show loss of chromatin accessibility at genes associated with T cell activation

As humans age, their memory T cell compartment expands due to the lifelong exposure to antigens. This expansion is characterized by terminally differentiated CD8+ T cells (Temra), which possess NK cell-like phenotype and are associated with chronic inflammatory conditions. Temra cells are predominantly driven by the sporadic reactivation of cytomegalovirus (CMV), yet their epigenomic patterns and cellular heterogeneity remain understudied. To address this gap, we correlated their gene expression profiles with chromatin openness and conducted single-cell transcriptome analysis, comparing them to other CD8+ subsets and CMV-responses. We confirmed that Temra cells exhibit high expression of genes associated with cytotoxicity and lower expression of costimulatory and chemokine genes. The data revealed that CMV-responsive CD8+ T cells (Tcmv) were predominantly derived from a mixed population of Temra and memory cells (Tcm/em) and shared their transcriptomic profiles. Using ATAC-seq analysis, we identified 1449 differentially accessible chromatin regions between CD8+ Temra and Tcm/em cells, of which only 127 sites gained chromatin accessibility in Temra cells. We further identified 51 gene loci, including costimulatory CD27, CD28, and ICOS genes, whose chromatin accessibility correlated with their gene expression. The differential chromatin regions Tcm/em cells were enriched in motifs that bind multiple transcriptional activators, such as Jun/Fos, NFkappaB, and STAT, whereas the open regions in Temra cells mainly contained binding sites of T-box transcription factors. Our single-cell analysis of CD8+CCR7loCD45RAhi sorted Temra population showed several subsets of Temra and NKT-like cells and CMC1+ Temra populations in older individuals that were shifted towards decreased cytotoxicity. Among CD8+CCR7loCD45RAhi sorted cells, we found a decreased proportion of IL7R+ Tcm/em-like and MAIT cells in individuals with high levels of CMV antibodies (CMVhi). These results shed new light on the molecular and cellular heterogeneity of CD8+ Temra cells and their relationship to aging and CMV infection.

Local delivery of cell surface-targeted immunocytokines programs systemic anti-tumor immunity

Cytokine therapies are potent immunotherapy agents but exhibit severe dose-limiting toxicities. One strategy to overcome this involves engineering cytokines for intratumoral retention following local delivery. Here, we develop a localized cytokine therapy that elicits profound anti-tumor immunity by engineered targeting to the ubiquitous leukocyte receptor CD45. We designed CD45-targeted immunocytokines (αCD45-Cyt) that, upon injection, decorated the surface of leukocytes in the tumor and tumor-draining lymph node (TDLN) without systemic exposure. αCD45-Cyt therapy eradicated both directly treated tumors and untreated distal lesions in multiple syngeneic mouse tumor models. Mechanistically, αCD45-Cyt triggered prolonged pSTAT signaling and reprogrammed tumor-specific CD8+ T cells in the TDLN to exhibit an anti-viral transcriptional signature. CD45 anchoring represents a broad platform for protein retention by host immune cells for use in immunotherapy.

The Entangled World of Memory T Cells and Implications in Transplantation

Memory T cells that are specific for alloantigen can arise from a variety of stimuli, ranging from direct allogeneic sensitization from prior transplantation, blood transfusion, or pregnancy to the elicitation of pathogen-specific T cells that are cross-reactive with alloantigen. Regardless of the mechanism by which they arise, alloreactive memory T cells possess key metabolic, phenotypic, and functional properties that render them distinct from naive T cells. These properties affect the immune response to transplantation in 2 important ways: first, they can alter the speed, location, and effector mechanisms with which alloreactive T cells mediate allograft rejection, and second, they can alter T-cell susceptibility to immunosuppression. In this review, we discuss recent developments in understanding these properties of memory T cells and their implications for transplantation.

DPA714 PET Imaging Shows That Inflammation of the Choroid Plexus Is Active in Chronic-Phase Intracerebral Hemorrhage

PURPOSE

Our aims were to investigate the presence of choroid plexus (CP) inflammation in chronic-phase intracerebral hemorrhage (ICH) patients and to characterize any inflammatory cells in the CP.

PATIENTS AND METHODS

An in vivo 18 F-DPA714 PET study was undertaken in 22 chronic-phase ICH patients who were admitted to the First Affiliated Hospital of Fujian Medical University or Tianjin Medical University General Hospital from April 2017 to June 2020. Ten control participants with nonhemorrhagic central nervous system diseases were included. Choroid plexus 18 F-DPA714 uptake was calculated as the average SUVR. To aid the interpretation of the 18 F-DPA714 uptake results at the CP level, Cy5-DPA714 in vivo imaging and immunofluorescence staining were used to show the presence of CP inflammation in an ICH mouse model during the chronic phase (14 weeks after ICH). Then immunofluorescence staining against translocator protein and other specific biomarkers was used to characterize the cells present in the inflamed CP of ICH mice in the chronic phase.

RESULTS

PET imaging showed that CP DPA714 SUVRs in chronic-phase ICH patients were higher than in controls (mean CP SUVR ± SD; ICH group: 1.05 ± 0.35; control group: 0.81 ± 0.21; P = 0.006). Immunofluorescence staining of the CP in ICH model mice identified a population of CD45 + immune cells, peripheral monocyte-derived CD14 + cells, CD68 + phagocytes, and CD11b + resident microglia/macrophages expressing translocator protein, possibly contributing to the increased 18 F-DPA714 uptake.

CONCLUSIONS

Our study shows that CP DPA714 uptake in chronic-phase ICH patients was higher than that of participants with nonhemorrhagic central nervous system diseases, which means that CP inflammation is still active in chronic-phase ICH patients.

CD45 limits early Natural Killer cell development

The clinical development of Natural Killer (NK) cell-mediated immunotherapy marks a milestone in the development of new cancer therapies and has gained traction due to the intrinsic ability of the NK cell to target and kill tumor cells. To fully harness the tumor killing ability of NK cells, we need to improve NK cell persistence and to overcome suppression of NK cell activation in the tumor microenvironment. The trans-membrane, protein tyrosine phosphatase CD45, regulates NK cell homeostasis, with the genetic loss of CD45 in mice resulting in increased numbers of mature NK cells. This suggests that CD45-deficient NK cells might display enhanced persistence following adoptive transfer. However, we demonstrate here that adoptive transfer of CD45-deficiency did not enhance NK cell persistence in mice, and instead, the homeostatic disturbance of NK cells in CD45-deficient mice stemmed from a developmental defect in the progenitor population. The enhanced maturation within the CD45-deficient NK cell compartment was intrinsic to the NK cell lineage, and independent of the developmental defect. CD45 is not a conventional immune checkpoint candidate, as systemic loss is detrimental to T and B cell development, compromising the adaptive immune system. Nonetheless, this study suggests that inhibition of CD45 in progenitor or stem cell populations may improve the yield of in vitro generated NK cells for adoptive therapy.

Circulating small extracellular vesicles microRNAs plus CA-125 for treatment stratification in advanced ovarian cancer

BACKGROUND

No residual disease (R0 resection) after debulking surgery is the most critical independent prognostic factor for advanced ovarian cancer (AOC). There is an unmet clinical need for selecting primary or interval debulking surgery in AOC patients using existing prediction models.

METHODS

RNA sequencing of circulating small extracellular vesicles (sEVs) was used to discover the differential expression microRNAs (DEMs) profile between any residual disease (R0, n = 17) and no residual disease (non-R0, n = 20) in AOC patients. We further analyzed plasma samples of AOC patients collected before surgery or neoadjuvant chemotherapy via TaqMan qRT-PCR. The combined risk model of residual disease was developed by logistic regression analysis based on the discovery-validation sets.

RESULTS

Using a comprehensive plasma small extracellular vesicles (sEVs) microRNAs (miRNAs) profile in AOC, we identified and optimized a risk prediction model consisting of plasma sEVs-derived 4-miRNA and CA-125 with better performance in predicting R0 resection. Based on 360 clinical human samples, this model was constructed using least absolute shrinkage and selection operator (LASSO) and logistic regression analysis, and it has favorable calibration and discrimination ability (AUC:0.903; sensitivity:0.897; specificity:0.910; PPV:0.926; NPV:0.871). The quantitative evaluation of Net Reclassification Improvement (NRI) and Integrated Discrimination Improvement (IDI) suggested that the additional predictive power of the combined model was significantly improved contrasted with CA-125 or 4-miRNA alone (NRI = 0.471, IDI = 0.538, p < 0.001; NRI = 0.122, IDI = 0.185, p < 0.01).

CONCLUSION

Overall, we established a reliable, non-invasive, and objective detection method composed of circulating tumor-derived sEVs 4-miRNA plus CA-125 to preoperatively anticipate the high-risk AOC patients of residual disease to optimize clinical therapy.

The Molecular Aspects of Functional Activity of Macrophage-Activating Factor GcMAF

Group-specific component macrophage-activating factor (GcMAF) is the vitamin D3-binding protein (DBP) deglycosylated at Thr420. The protein is believed to exhibit a wide range of therapeutic properties associated with the activation of macrophagal immunity. An original method for GcMAF production, DBP conversion to GcMAF, and the analysis of the activating potency of GcMAF was developed in this study. Data unveiling the molecular causes of macrophage activation were obtained. GcMAF was found to interact with three CLEC10A derivatives having molecular weights of 29 kDa, 63 kDa, and 65 kDa. GcMAF interacts with high-molecular-weight derivatives via Ca2+-dependent receptor engagement. Binding to the 65 kDa or 63 kDa derivative determines the pro- and anti-inflammatory direction of cytokine mRNA expression: 65 kDa-pro-inflammatory (TNF-α, IL-1β) and 63 kDa-anti-inflammatory (TGF-β, IL-10). No Ca2+ ions are required for the interaction with the canonical 29 kDa CLEC10A. Both forms, DBP protein and GcMAF, bind to the 29 kDa CLEC10A. This interaction is characterized by the stochastic mRNA synthesis of the analyzed cytokines. Ex vivo experiments have demonstrated that when there is an excess of GcMAF ligand, CLEC10A forms aggregate, and the mRNA synthesis of analyzed cytokines is inhibited. A schematic diagram of the presumable mechanism of interaction between the CLEC10A derivatives and GcMAF is provided. The principles and elements of standardizing the GcMAF preparation are elaborated.

Expression of viral CD45 ligand E3/49K on porcine cells reduces human anti-pig immune responses

Transgenic expression of protective molecules in porcine cells and tissues is a promising approach to prevent xenograft rejection. Viruses have developed various strategies to escape the host's immune system. We generated porcine B cells (B cell line L23) expressing the human adenovirus protein E3/49K or the human cytomegalovirus protein pUL11 and investigated how human T, NK and B cell responses are affected by the expression of the viral proteins. Binding studies revealed that E3/49K and pUL11 interact with CD45 on human but not porcine peripheral blood mononuclear cells. T cell proliferation in response to L23-E3/49K cells was significantly reduced and accompanied by development of an anti-inflammatory cytokine milieu (low: TNF-alpha, IFN-gamma, IL-6; high: IL-4, IL-10). Human peripheral blood mononuclear cells which had been primed for four weeks by L23-E3/49K cells included an extended population of regulatory T cells. Cytotoxicity of effector T and natural killer cells against L23 cells was significantly reduced (40 to 50%) by E3/49K expression. B cell activation and antibody production to E3/49K expressing cells was also diminished. Surprisingly, pUL11 expression showed no effects. Reduction of human anti-pig immune responses by transgenic expression of selected viral genes may be a novel approach for protection of porcine xenografts.

Exploring Colitis through Dynamic T Cell Adoptive Transfer Models

Numerous animal models of colitis have provided important insights into the pathogenesis of inflammatory bowel disease (IBD), contributing to a better understanding of the underlying mechanisms for IBD. As aberrant CD4+ T cell responses play a critical role in the pathogenesis and development of IBD, T cell adoptive transfer models of colitis have become a valuable tool in investigating the immunopathogenesis of intestinal inflammation. While the adoptive transfer of CD4+ CD45RBhi T cells into immunedeficient recipient mice was the first discovered and is currently the most widely used model, several variations of the T cell transfer model have also been developed with distinct features. Here, we describe the history, principle, and characteristics of adoptive transfer colitis models and discuss their strengths, limitations, and applications.

Alternative splicing events and function in the tumor microenvironment: New opportunities and challenges

Alternative splicing controls gene expression at the transcriptional level, producing structurally and functionally distinct protein heterodimers. Aberrant alternative splicing greatly affects cell development and plays an important role in the invasion and metastasis of many types of cancer. Recently, it has been shown that alternative splicing can alter the tumor microenvironment and regulate processes such as remodeling, immunity, and inflammation in the tumor microenvironment. However, there is no comprehensive literature review of the complex relationship between alternative splicing and the tumor microenvironment. Therefore, this review aims to collect all the latest data on this topic and provide a new perspective on the therapeutic and potential prognostic markers of cancer.

A machine-learning model that incorporates CD45 surface expression predicts hematopoietic progenitor cell recovery after freeze-thaw

BACKGROUND AIMS

Sufficient doses of viable CD34+ (vCD34) hematopoietic progenitor cells (HPCs) are crucial for engraftment. Additional-day apheresis collections can compensate for potential loss during cryopreservation but incur high cost and additional risk. To aid predicting such losses for clinical decision support, we developed a machine-learning model using variables obtainable on the day of collection.

METHODS

In total, 370 consecutive autologous HPCs, apheresis-collected since 2014 at the Children's Hospital of Philadelphia, were retrospectively reviewed. Flow cytometry was used to assess vCD34% on fresh products and thawed quality control vials. The ratio of vCD34% thawed to fresh, which we call "post-thaw index," was used as an outcome measure, with a "poor" post-thaw index defined as <70%. HPC CD45 normalized mean fluorescence intensity (MFI) was calculated by dividing CD45 MFI of HPCs to the CD45 MFI of lymphocytes in the same sample. We trained XGBoost, k-nearest neighbor and random forest models for the prediction and calibrated the best model to minimize falsely-reassuring predictions.

RESULTS

In total, 63 of 370 (17%) products had a poor post-thaw index. The best model was XGBoost, with an area under the receiver operator curve of 0.83 evaluated on an independent test data set. The most important predictor for a poor post-thaw index was the HPC CD45 normalized MFI. Transplants after 2015, based on the lower of the two vCD34% values, showed faster engraftment than older transplants, which were based on fresh vCD34% only (average 10.6 vs 11.7 days, P = 0.0006).

CONCLUSIONS

Transplants taking into account post-thaw vCD34% improved engraftment time in our patients; however, it came at the cost of unnecessary multi-day collections. The results from applying our predictive algorithm retrospectively to our data suggest that more than one-third of additional-day collections could have been avoided. Our investigation also identified CD45 nMFI as a novel marker for assessing HPC health post-thaw.

Epitope base editing CD45 in hematopoietic cells enables universal blood cancer immune therapy

In the absence of cell surface cancer-specific antigens, immunotherapies such as chimeric antigen receptor (CAR) T cells, monoclonal antibodies, or bispecific T cell engagers typically target lineage antigens. Currently, such immunotherapies are individually designed and tested for each disease. This approach is inefficient and limited to a few lineage antigens for which the on-target/off-tumor toxicities are clinically tolerated. Here, we sought to develop a universal CAR T cell therapy for blood cancers directed against the pan-leukocyte marker CD45. To protect healthy hematopoietic cells, including CAR T cells, from CD45-directed on-target/off-tumor toxicity while preserving the essential functions of CD45, we mapped the epitope on CD45 that is targeted by the CAR and used CRISPR adenine base editing to install a function-preserving mutation sufficient to evade CAR T cell recognition. Epitope-edited CD45 CAR T cells were fratricide resistant and effective against patient-derived acute myeloid leukemia, B cell lymphoma, and acute T cell leukemia. Epitope-edited hematopoietic stem cells (HSCs) were protected from CAR T cells and, unlike CD45 knockout cells, could engraft, persist, and differentiate in vivo. Ex vivo epitope editing in HSCs and T cells enables the safe and effective use of CD45-directed CAR T cells and bispecific T cell engagers for the universal treatment of hematologic malignancies and might be exploited for other diseases requiring intensive hematopoietic ablation.

A phase I clinical trial of oncolytic adenovirus mediated suicide and interleukin-12 gene therapy in patients with recurrent localized prostate adenocarcinoma

In a phase I dose escalation and safety study (NCT02555397), a replication-competent oncolytic adenovirus expressing yCD, TK and hIL-12 (Ad5-yCD/mutTKSR39rep-hIL-12) was administered in 15 subjects with localized recurrent prostate cancer (T1c-T2) at increasing doses (1 × 1010, to 1 × 1012 viral particles) followed by 7-day treatment of 5-fluorocytosine (5-FC) and valganciclovir (vGCV). The primary endpoint was toxicity through day 30 while the secondary and exploratory endpoints were quantitation of IL-12, IFNγ, CXCL10 and peripheral blood mononuclear cells (PBMC). The study maximum tolerated dose (MTD) was not reached indicating 1012 viral particles was safe. Total 115 adverse events were observed, most of which (92%) were grade 1/2 that did not require any treatment. Adenoviral DNA was detected only in two patients. Increase in IL-12, IFNγ, and CXCL10 was observed in 57%, 93%, and 79% patients, respectively. Serum cytokines demonstrated viral dose dependency, especially apparent in the highest-dose cohorts. PBMC analysis revealed immune system activation after gene therapy in cohort 5. The PSA doubling time (PSADT) pre and post treatment has a median of 1.55 years vs 1.18 years. This trial confirmed that replication-competent Ad5-IL-12 adenovirus (Ad5-yCD/mutTKSR39rep-hIL-12) was well tolerated when administered locally to prostate tumors.

Dendritic cell type 3 arises from Ly6C+ monocyte-dendritic cell progenitors

Conventional dendritic cells (cDCs) are professional antigen-presenting cells that control the adaptive immune response. Their subsets and developmental origins have been intensively investigated but are still not fully understood as their phenotypes, especially in the DC2 lineage and the recently described human DC3s, overlap with monocytes. Here, using LEGENDScreen to profile DC vs. monocyte lineages, we found sustained expression of FLT3 and CD45RB through the whole DC lineage, allowing DCs and their precursors to be distinguished from monocytes. Using fate mapping models, single-cell RNA sequencing and adoptive transfer, we identified a lineage of murine CD16/32+CD172a+ DC3, distinct from DC2, arising from Ly6C+ monocyte-DC progenitors (MDPs) through Lyz2+Ly6C+CD11c- pro-DC3s, whereas DC2s develop from common DC progenitors (CDPs) through CD7+Ly6C+CD11c+ pre-DC2s. Corresponding DC subsets, developmental stages, and lineages exist in humans. These findings reveal DC3 as a DC lineage phenotypically related to but developmentally different from monocytes and DC2s.

Dickkopf-1 promotes vascular smooth muscle cell foam cell formation and atherosclerosis development through CYP4A11/SREBP2/ABCA1

Vascular smooth muscle cells (VSMCs) are considered to be a crucial source of foam cells in atherosclerosis due to their low expression level of cholesterol exporter ATP-binding cassette transporter A1 (ABCA1) intrinsically. While the definite regulatory mechanisms are complicated and have not yet been fully elucidated, we previously reported that Dickkopf-1 (DKK1) mediates endothelial cell (EC) dysfunction, thereby aggravating atherosclerosis. However, the role of smooth muscle cell (SMC) DKK1 in atherosclerosis and foam cell formation remains unknown. In this study, we established SMC-specific DKK1-knockout (DKK1SMKO ) mice by crossbreeding DKK1flox/flox mice with TAGLN-Cre mice. Then, DKK1SMKO mice were crossed with APOE-/- mice to generate DKK1SMKO /APOE-/- mice, which exhibited milder atherosclerotic burden and fewer SMC foam cells. In vitro loss- and gain-of-function studies of DKK1 in primary human aortic smooth muscle cells (HASMCs) have proven that DKK1 prevented oxidized lipid-induced ABCA1 upregulation and cholesterol efflux and promoted SMC foam cell formation. Mechanistically, RNA-sequencing (RNA-seq) analysis of HASMCs as well as chromatin immunoprecipitation (ChIP) experiments showed that DKK1 mediates the binding of transcription factor CCAAT/enhancer-binding protein delta (C/EBPδ) to the promoter of cytochrome P450 epoxygenase 4A11 (CYP4A11) to regulate its expression. In addition, CYP4A11 as well as its metabolite 20-HETE-promoted activation of transcription factor sterol regulatory element-binding protein 2 (SREBP2) mediated the DKK1 regulation of ABCA1 in SMC. Furthermore, HET0016, the antagonist of CYP4A11, has also shown an alleviating effect on atherosclerosis. In conclusion, our results demonstrate that DKK1 promotes SMC foam cell formation during atherosclerosis via a reduction in CYP4A11-20-HETE/SREBP2-mediated ABCA1 expression.

Muscle denervation promotes functional interactions between glial and mesenchymal cells through NGFR and NGF

We performed scRNA-seq/snATAC-seq of skeletal muscles post sciatic nerve transection to delineate cell type-specific patterns of gene expression/chromatin accessibility at different time points post-denervation. Unlike myotrauma, denervation selectively activates glial cells and Thy1/CD90-expressing mesenchymal cells. Glial cells expressed Ngf receptor (Ngfr) and were located near neuromuscular junctions (NMJs), close to Thy1/CD90-expressing cells, which provided the main cellular source of NGF post-denervation. Functional communication between these cells was mediated by NGF/NGFR, as either recombinant NGF or co-culture with Thy1/CD90-expressing cells could increase glial cell number ex vivo. Pseudo-time analysis in glial cells revealed an initial bifurcation into processes related to either cellular de-differentiation/commitment to specialized cell types (e.g., Schwann cells), or failure to promote nerve regeneration, leading to extracellular matrix remodeling toward fibrosis. Thus, interactions between denervation-activated Thy1/CD90-expressing and glial cells represent an early abortive process toward NMJs repair, ensued by the conversion of denervated muscles into an environment hostile for NMJ repair.

CD45RA and CD45RO Are Regulated in a Cell-Type Specific Manner in Inflammation and Sepsis

CD45 is a transmembrane glycoprotein that is located on the surface of all leukocytes and modulates both innate and adaptive immune system functions. In a recent study, inflammation modulated the CD45 expression in leukocytes, but the effect on the expression of CD45 subtypes is unknown. In the present study, we therefore investigated the effect of inflammatory conditions in humans (surgery, sepsis) and ex vivo incubation with lipopolysaccharides (LPS) on the expression of the subtypes CD45RA and CD45RO in granulocytes, lymphocytes, and monocytes. Whole blood samples were obtained from healthy volunteers, postoperative patients, and patients with sepsis at day 1 of diagnosis, respectively. Samples were incubated with fluorescent antibodies directed against CD45, CD45RA and CD45RO in the absence and presence of lipopolysaccharide and subjected to flow cytometry. In comparison to volunteers, CD45RA surface expression in postoperative and septic patients was reduced by 89% exclusively on granulocytes, but not on lymphocytes or monocytes. In contrast, CD45RO was exclusively reduced on lymphocytes, by 82%, but not on other cell types. Receiver operating characteristic curve analyses demonstrated that CD45RA (on granulocytes) and CD45RO (on lymphocytes) allow a good differentiation of volunteers and patients with sepsis (AUC = 0.9; p = 0.0001). The addition of LPS to the whole blood samples obtained from volunteers, postoperative patients, and septic patients markedly increased the CD45RO expression in granulocytes, lymphocytes, and monocytes. In contrast, LPS reduced CD45RA exclusively on monocytes. In conclusion, the surface expression of CD45RA and CD45RO is regulated in inflammation in a cell-type- and stimulus-specific manner. Considering that CD45 subtypes are critically involved in immune system signaling, the pathophysiologic and diagnostic implications warrant further investigation.

Mitochondria-related genes and metabolic profiles of innate and adaptive immune cells in primary Sjögren's syndrome

Background

Primary Sjogren's syndrome (pSS) is a prototypical systemic autoimmune disease characterised by lymphocyte infiltration and immune-complex deposition in multiple organs. The specific distribution of immune cell populations and their relationship with mitochondria remain unknown.

Methods

Histological analysis was performed to assess the specific distribution of innate and adaptive immune cell populations in labial salivary gland (LSG) samples from 30 patients with pSS and 13 patients with non-pSS. The ultrastructural morphometric features of mitochondria within immune cells were observed under the transmission electron microscope (TEM). RNA sequencing was performed on LSG samples from 40 patients with pSS and 7 non-pSS patients. The Single-sample Gene Set Enrichment Analysis (ssGSEA), ESTIMATE, and CIBERSORT algorithms and Pearson correlation coefficients were used to examine the relationship between mitochondria-related genes and immune infiltration. Weighted Gene Co-expression Network Analysis (WGCNA) was used to identify the mitochondria-specific genes and the related pathways based on the immune cell types.

Results

HE staining revealed a massive infiltration of plasma cells with abundant immunoglobulin protein distributed around phenotypically normal-appearing acinar and ductal tissues of patients with pSS. Immunohistochemical analyses revealed that innate immune cells (macrophages, eosinophils and NK cells) were distributed throughout the glandular tissue. Dominant adaptive immune cell infiltration composed of B cells, CD4⁺T cells and CD8⁺ T cells or ectopic lymphoid follicle-like structures were observed in the LSGs of patients with pSS. TEM validated the swelling of mitochondria with disorganised cristae in some lymphocytes that had invaded the glandular tissue. Subsequently, bioinformatic analysis revealed that innate and adaptive immune cells were associated with different mitochondrial metabolism pathways. Mitochondrial electron transport and respiratory chain complexes in the glandular microenvironment were positively correlated with innate immune cells, whereas amino acid and nucleic acid metabolism were negatively correlated with adaptive immune cells. In addition, mitochondrial biogenesis and mitochondrial apoptosis in the glandular microenvironment were closely associated with adaptive immune cells.

Conclusion

Innate and adaptive immune cells have distinct distribution profiles in the salivary gland tissues of patients with pSS and are associated with different mitochondrial metabolic pathways, which may contribute to disease progression.

Membrane-anchored DNA nanojunctions enable closer antigen-presenting cell-T-cell contact in elevated T-cell receptor triggering

How the engagement of a T-cell receptor to antigenic peptide-loaded major histocompatibility complex on antigen-presenting cells (APCs) initiates intracellular signalling cascades in T cells is not well understood. In particular, the dimension of the cellular contact zone is regarded as a determinant, but its influence remains controversial. This is due to the need for appropriate strategies for manipulating intermembrane spacing between the APC-T-cell interfaces without involving protein modification. Here we describe a membrane-anchored DNA nanojunction with distinct sizes to extend, maintain and shorten the APC-T-cell interface down to 10 nm. Our results suggest that the axial distance of the contact zone is critical in T-cell activation, presumably by modulating protein reorganization and mechanical force. Notably, we observe the promotion of T-cell signalling by shortening the intermembrane distance.

Protein Tyrosine Phosphatase CD45 As an Immunity Regulator and a Potential Effector of CAR-T therapy

The leukocyte common antigen CD45 is a receptor tyrosine phosphatase and one of the most prevalent antigens found on the surface of blood cells. CD45 plays a crucial role in the initial stages of signal transmission from receptors of various immune cell types. Immunodeficiency, autoimmune disorders, and oncological diseases are frequently caused by gene expression disorders and imbalances in CD45 isoforms. Despite extensive research into the structure and functions of CD45, the molecular mechanisms behind its role in transmitting signals from T-cell receptors and chimeric antigen receptors remain not fully understood. It is of utmost importance to comprehend the structural features of CD45 and its function in regulating immune system cell activation to study oncological diseases and the impact of CD45 on lymphocytes and T cells modified by chimeric antigen receptors.

Revolutionizing anti-tumor therapy: unleashing the potential of B cell-derived exosomes

B cells occupy a vital role in the functioning of the immune system, working in tandem with T cells to either suppress or promote tumor growth within the tumor microenvironment(TME). In addition to direct cell-to-cell communication, B cells and other cells release exosomes, small membrane vesicles ranging in size from 30-150 nm, that facilitate intercellular signaling. Exosome research is an important development in cancer research, as they have been shown to carry various molecules such as major histocompatibility complex(MHC) molecules and integrins, which regulate the TME. Given the close association between TME and cancer development, targeting substances within the TME has emerged as a promising strategy for cancer therapy. This review aims to present a comprehensive overview of the contributions made by B cells and exosomes to the tumor microenvironment (TME). Additionally, we delve into the potential role of B cell-derived exosomes in the progression of cancer.

Enforced Dimerization of CD45 by the Adenovirus E3/49K Protein Inhibits T Cell Receptor Signaling

Human adenoviruses (HAdVs) are widespread pathogens that generally cause mild infections in immunocompetent individuals but severe or even fatal diseases in immunocompromised patients. In order to counteract the host immune defenses, HAdVs encode various immunomodulatory proteins in the early transcription unit 3 (E3). The E3/49K protein is a highly glycosylated type I transmembrane protein uniquely expressed by species D HAdVs. Its N-terminal ectodomain sec49K is released by metalloprotease-mediated shedding at the cell surface and binds to the receptor-like protein tyrosine phosphatase CD45, a critical regulator of leukocyte activation and functions. It remained elusive which domains of CD45 and E3/49K are involved in the interaction and whether such an interaction can also occur on the cell surface with membrane-anchored full-length E3/49K. Here, we show that the two extracellular domains R1 and R2 of E3/49K bind to the same site in the domain d3 of CD45. This interaction enforces the dimerization of CD45, causing the inhibition of T cell receptor signaling. Intriguingly, the membrane-anchored E3/49K appears to be designed like a "molecular fishing rod" using an extended disordered region of E3/49K as a "fishing line" to bridge the distance between the plasma membrane of infected cells and the CD45 binding site on T cells to effectively position the domains R1 and R2 as baits for CD45 binding. This design strongly suggests that both secreted sec49K as well as membrane-anchored full-length E3/49K have immunomodulatory functions. The forced dimerization of CD45 may be applied as a therapeutic strategy in chronic inflammatory disorders and cancer. IMPORTANCE The battle between viruses and their hosts is an ongoing arms race. Whereas the host tries to detect and eliminate the virus, the latter counteracts such antiviral measures to replicate and spread. Adenoviruses have evolved various mechanisms to evade the human immune response. The E3/49K protein of species D adenoviruses mediates the inhibition of immune cell function via binding to the protein tyrosine phosphatase CD45. Here, we show that E3/49K triggers the dimerization of CD45 and thereby inhibits its phosphatase activity. Intriguingly, the membrane-anchored E3/49K seems to be designed like a "molecular fishing rod" with the two CD45 binding domains of E3/49K as baits positioned at the end of an extended disordered region reminiscent of a fishing line. The adenoviral strategy to inhibit CD45 activity by forced dimerization may be used for therapeutic intervention in autoimmune diseases or to prevent graft rejection after transplantation.

Effects of Therapeutic Hypothermia on Macrophages in Mouse Cochlea Explants

Globally, over the next few decades, more than 2.5 billion people will suffer from hearing impairment, including profound hearing loss, and millions could potentially benefit from a cochlea implant. To date, several studies have focused on tissue trauma caused by cochlea implantation. The direct immune reaction in the inner ear after an implantation has not been well studied. Recently, therapeutic hypothermia has been found to positively influence the inflammatory reaction caused by electrode insertion trauma. The present study aimed to evaluate the hypothermic effect on the structure, numbers, function and reactivity of macrophages and microglial cells. Therefore, the distribution and activated forms of macrophages in the cochlea were evaluated in an electrode insertion trauma cochlea culture model in normothermic and mild hypothermic conditions. In 10-day-old mouse cochleae, artificial electrode insertion trauma was inflicted, and then they were cultured for 24 h at 37 °C and 32 °C. The influence of mild hypothermia on macrophages was evaluated using immunostaining of cryosections using antibodies against IBA1, F4/80, CD45 and CD163. A clear influence of mild hypothermia on the distribution of activated and non-activated forms of macrophages and monocytes in the inner ear was observed. Furthermore, these cells were located in the mesenchymal tissue in and around the cochlea, and the activated forms were found in and around the spiral ganglion tissue at 37 °C. Our findings suggest that mild hypothermic treatment has a beneficial effect on immune system activation after electrode insertion trauma.

Optical imaging of the small intestine immune compartment across scales

The limitations of 2D microscopy constrain our ability to observe and understand tissue-wide networks that are, by nature, 3-dimensional. Optical projection tomography (OPT) enables the acquisition of large volumes (ranging from micrometres to centimetres) in various tissues. We present a multi-modal workflow for the characterization of both structural and quantitative parameters of the mouse small intestine. As proof of principle, we evidence its applicability for imaging the mouse intestinal immune compartment and surrounding mucosal structures. We quantify the volumetric size and spatial distribution of Isolated Lymphoid Follicles (ILFs) and quantify the density of villi throughout centimetre-long segments of intestine. Furthermore, we exhibit the age and microbiota dependence for ILF development, and leverage a technique that we call reverse-OPT for identifying and homing in on regions of interest. Several quantification capabilities are displayed, including villous density in the autofluorescent channel and the size and spatial distribution of the signal of interest at millimetre-scale volumes. The concatenation of 3D imaging with reverse-OPT and high-resolution 2D imaging allows accurate localisation of ROIs and adds value to interpretations made in 3D. Importantly, OPT may be used to identify sparsely-distributed regions of interest in large volumes whilst retaining compatibility with high-resolution microscopy modalities, including confocal microscopy. We believe this pipeline to be approachable for a wide-range of specialties, and to provide a new method for characterisation of the mouse intestinal immune compartment.

Cholesterol-conjugated siRNAs silence gene expression in mucosal dendritic cells in cervicovaginal tissue in mice

BACKGROUND

RNA interference (RNAi) provides a powerful way to investigate the role of genes in disease pathogenesis and modulate gene expression to treat disease. In 2018, the FDA approved patisiran, the first RNAi-based drug, hence paving the way for a novel class of RNAi therapeutics. Harnessing RNAi to inhibit vaginal HIV transmission requires effective gene silencing in immune cells, which remains difficult. Knockdown in accessible mucosal tissues may be easier than systemic gene silencing. Vaginally applied cholesterol-conjugated small interfering RNAs (chol-siRNAs) blocked herpes simplex virus transmission in mice without tissue damage or immunostimulation.

OBJECTIVES AND METHODS

To investigate using flow cytometry, confocal microscopy, and quantitative imaging if chol-siRNAs silence gene expression in vaginal immune cells in mice.

RESULTS

Although chol-siRNAs and lipoplexed-siRNAs silence gene expression in dendritic cells (DCs) in vitro, most internalized siRNAs concentrate within multivesicular bodies, where they are inaccessible to the cellular RNAi machinery. When applied intravaginally in vivo, chol-siRNAs penetrate the vaginal mucosa, including the lamina propria, and are efficiently internalized by intraepithelial (IE) and lamina propria (LP) DCs, and CD11b⁺ CD45⁺ cells, but not by T cells. Chol-siRNAs induce partial gene silencing in IE and LP DCs throughout the genital mucosa in vivo but are inactive in F4/80⁺ CD11b⁺ macrophages and T cells.

CONCLUSION

As mucosal DCs play an essential role for mucosal viral entry and dissemination, chol-siRNAs could be harnessed to target various host factors that are critical for viral uptake, DC migration and trans-infection of virions to T cells, hence allowing the development of a preventive vaginal HIV microbicide. Furthermore, chol-siRNAs could help elucidate the pathways of HIV transmission and understand the immunologic function of DCs in the genital tract.

Neoplastic bone marrow invasion:rapid exclusion of hematological disease by flow cytometric routine panels

Multiparametric flow cytometry is an extensively used technique to assess the presence of different cellular populations in immunology and hematology. During routine immunophenotyping analysis, it is not uncommon to face cells of non-hemopoietic origin, negative for CD45 and other myeloid, megakaryocytic, B and T lineage antigens and positive for at least one antibody among CD56, CD117 and CD138. If cytology cannot identify cell origin, especially in cases of unclear interpretation, the contribution of multiparametric flow cytometry analysis can be crucial. We report 6 patients with a clinical suspicion of hematological disease in which multiparametric flow cytometry was extremely useful to quickly exclude blood disorders in order to initiate patients to the most appropriate diagnostic process.

Allogeneic cord blood regulatory T cells can resolve lung inflammation

BACKGROUND AIMS

CD4⁺CD25⁺CD127^lo regulatory T cells (Tregs) are responsible for maintaining immune homeostasis. Tregs can be rendered defective and deficient as a result of the immune imbalance seen in lung injury, and such dysfunction can play a major role in continued tissue inflammation. The authors hypothesized that adoptive therapy with healthy allogeneic umbilical cord blood (UCB)-derived Tregs may be able to resolve inflammation.

RESULTS

Ex vivo-expanded UCB Tregs exhibited a unique phenotype with co-expression of CD45RA⁺CD45RO⁺ >80% and lung homing markers, including CD49d. UCB Tregs did not turn pathogenic when exposed to IL-6. Co-culture with increasing doses of dexamethasone led to a synergistic increase in UCB Treg-induced apoptosis of conventional T cells (Tcons), which translated into significantly higher suppression of proliferating Tcons, especially at a lower Treg:Tcon ratio. Multiple injections of UCB Tregs led to their preferential accumulation in lung tissue in an immune injury xenogenic model. A significant decrease in lung resident cytotoxic CD8⁺ T cells (P = 0.0218) correlated with a sustained decrease in their systemic distribution compared with controls (P < 0.0001) (n = 7 per arm) as well as a decrease in circulating human soluble CD40 ligand level (P = 0.031). Tissue architecture was preserved in the treatment arm, and a significant decrease in CD3⁺ and CD8⁺ burden was evident in immunohistochemistry analysis.

CONCLUSIONS

UCB Treg adoptive therapy is a promising therapeutic strategy for treatment of lung injury.

Shaping Heterogeneity of Naive CD8+ T Cell Pools

Immune diversification helps protect the host against a myriad of pathogens. CD8⁺ T cells are essential adaptive immune cells that inhibit the spread of pathogens by inducing apoptosis in infected host cells, ultimately ensuring complete elimination of infectious pathogens and suppressing disease development. Accordingly, numerous studies have been conducted to elucidate the mechanisms underlying CD8⁺ T cell activation, proliferation, and differentiation into effector and memory cells, and to identify various intrinsic and extrinsic factors regulating these processes. The current knowledge accumulated through these studies has led to a huge breakthrough in understanding the existence of heterogeneity in CD8⁺ T cell populations during immune response and the principles underlying this heterogeneity. As the heterogeneity in effector/memory phases has been extensively reviewed elsewhere, in the current review, we focus on CD8⁺ T cells in a "naïve" state, introducing recent studies dealing with the heterogeneity of naive CD8⁺ T cells and discussing the factors that contribute to such heterogeneity. We also discuss how this heterogeneity contributes to establishing the immense complexity of antigen-specific CD8⁺ T cell response.