Natural Killer Cells: Potential Biomarkers and Therapeutic Target in Autoimmune Diseases?

Cellular therapies in rheumatic and musculoskeletal diseases

A substantial proportion of patients diagnosed with rheumatologic and musculoskeletal diseases (RMDs) exhibit resistance to conventional therapies or experience recurrent symptoms. These diseases, which include autoimmune disorders such as multiple sclerosis, rheumatoid arthritis, and systemic lupus erythematosus, are marked by the presence of autoreactive B cells that play a critical role in their pathogenesis. The persistence of these autoreactive B cells within lymphatic organs and inflamed tissues impairs the effectiveness of B-cell-depleting monoclonal antibodies like rituximab. A promising therapeutic approach involves using T cells genetically engineered to express chimeric antigen receptors (CARs) that target specific antigens. This strategy has demonstrated efficacy in treating B-cell malignancies by achieving long-term depletion of malignant and normal B cells. Preliminary data from patients with RMDs, particularly those with lupus erythematosus and dermatomyositis, suggest that CAR T-cells targeting CD19 can induce rapid and sustained depletion of circulating B cells, leading to complete clinical and serological responses in cases that were previously unresponsive to conventional therapies. This review will provide an overview of the current state of preclinical and clinical studies on the use of CAR T-cells and other cellular therapies for RMDs. Additionally, it will explore potential future applications of these innovative treatment modalities for managing patients with refractory and recurrent manifestations of these diseases.

Advances in research on flavonoids in tumor immunotherapy (Review)

Cancer immunotherapy is an approach used in anti‑tumor treatment; however, its efficacy is limited to specific tumor types that are inherently sensitive to immune system modulation. Expanding the scope of indications and enhancing the efficacy of cancer immunotherapy are key goals for continued advancement. Flavonoids modulate the tumor‑immunosuppressive microenvironment. Integrating flavonoids with immunotherapeutic modalities, including cancer vaccines, immune checkpoint inhibitors and adoptive immune‑cell therapy, has potential in terms of augmenting the therapeutic efficacy of immunotherapy. The present review aimed to summarize flavonoids that enhance cancer immunotherapy, focusing on their underlying mechanisms and the application of nanotechnology to overcome inherent limitations such as poor solubility, low bioavailability, rapid metabolism, and instability under physiological conditions, thereby highlighting the potential of flavonoids in advancing cancer immunotherapy.

Whole-Blood RNA Sequencing Profiling of Patients With Rheumatoid Arthritis Treated With Tofacitinib

OBJECTIVE

Patients with rheumatoid arthritis (RA) often fail to respond to therapies, including JAK inhibitors (JAKi), and treatment allocation is made via a trial-and-error strategy. A comprehensive analysis of responses to JAKi, including tofacitinib, by RNA sequencing (RNAseq) would allow the discovery of transcriptomic markers with a two-fold meaning: (1) an improved knowledge about the mechanisms of response to treatment (inference modeling) and (2) the definition of features that may be useful in treatment optimization and assignment (predictive modeling).

METHODS

Thirty-three patients with active RA were treated with a tofacitinib dose of 5 mg twice a day for 24 weeks and evaluated for EULAR Disease Activity Score in 28 joints using the C-reactive protein level response. Whole-blood RNA was collected before and after treatment to perform RNAseq transcriptome analysis. Linear models were used to determine differentially expressed genes (DEGs) (1) at baseline according to clinical responses and (2) in the pre-post comparison after tofacitinib treatment and in relation to EULAR responses. The capability of DEGs to predict a successful treatment was tested via machine learning modeling after extensive internal validation.

RESULTS

Of 26 patients who completed the study (per-protocol analysis), 15 (57.7%) achieved good responses, and 7 (26.9%) and 4 (15.3%) had moderate and no responses, respectively. Overall, 273 baseline genes were significantly associated with the attainment of good responses, contributing to several pathways linked to the immune system or RA pathogenesis (eg, citrullination processes and the negative regulation of natural killer function). The expression of several molecules was reverted by tofacitinib when good responses were reached, including AKT3, GK5, KLF12, FCRL3, BIRC3, TSPOAP1, and P2RY10. Finally, we isolated 14 markers that singularly were capable of predicting the attainment of good responses, including, NKG2D, CD226, CLEC2D, and CD52.

CONCLUSION

Whole-blood transcriptome analysis of patients with RA treated with tofacitinib identified genes whose expression may be relevant in prognostication and understanding the mechanisms of responses to therapy.

Correlation among ocular surface changes and systemic hematologic indexes and disease activity in primary Sjögren's syndrome: a cross-sectional study

BACKGROUND

To explore the relationship among ocular surface changes, systemic hematologic indexes, and disease activity in primary Sjögren's syndrome patients.

METHODS

Thirty-three primary Sjögren's syndrome patients and 36 healthy controls were recruited in this cross-sectional study. All participants underwent complete ocular surface testing, including dry eye symptoms and signs, tear multi-cytokine analysis, and conjunctival impression cytology (CIC). Multiple systemic hematologic indexes and disease activity were also evaluated, including autoantibodies, immune cells, the EULAR Sjögren's Syndrome Patient Reported Index (ESSPRI), and the EULAR Sjögren's Syndrome Disease Activity Index (ESSDAI).

RESULTS

Primary Sjögren's syndrome patients exhibited significant dry eye, severe conjunctivochalasis, decreased goblet cell density, and severe squamous epithelial on the ocular surface. Interferon-inducible T cell alpha chemoattractant (I-TAC), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin (IL)-1β, IL-5, IL-8, IL-10, IL-13, IL-21, C-C motif chemokine ligand (CCL)4, interferon-gamma (IFN-γ), CCL20, and tumor necrosis factor-gamma (TNF-α) in the tear fluid of pSS patients changed significantly. Correlation analysis showed that anti-SSA was relevant to ocular surface disease index (OSDI) score, tear break-up time (TBUT), and meibomian gland secretion (MGS). CD8+ T cell percentages were relevant to TBUT and corneal fluorescein staining score (CFS). IL-8, IL-13, CCL4, and TNF-α were correlated with RF-IgA. IL-1β, CCL4, and TNF-α were correlated with CD8+ T cell counts. IL-5 and CCL20 were correlated with the ratio of helper T cells and suppressor T cells. Tear I-TAC, IL-8, CCL20, and TNF-α were significantly correlated with the ESSDAI of different domains.

CONCLUSIONS

Our results revealed that the ocular surface changes in pSS patients were significantly correlated with systemic hematologic indexes and disease activity.

Natural killer cells in multiple sclerosis: foe or friends?

Multiple sclerosis (MS) is an immune-mediated disorder involving the central nervous system (CNS), in which demyelination is caused. The initiation and progression of MS is thought to depend largely on CD4+ T lymphocytes, yet new data has emphasized the involvement of the innate immune system in the MS disease responses. Generally, several types of immune cells play a part, with natural killer (NK) cells being essential. Different subsets of natural killer cells function differently within the course of an autoimmune disease, such as MS. There are mainly two types of natural killers in humans: immature CD56 bright CD16- and mature CD56 dim CD16+ natural killers, together with their respective subtypes. Factors from natural killers expand the T cell population and control the process by which native CD4+ T cells differentiate into Th1 or Th2 lymphocytes, which affect autoimmune responses. Natural killer subsets CD56 bright and CD56 dim may have differing roles in MS development. The impact of these NK cell subsets is influenced by factors such as Granzymes, genetics, infections, TLR, and HSP. We reviewed and evaluated the relationship between natural killer cells and MS.

Impact of immune cell metabolism on membranous nephropathy and prospective therapy

Membranous nephropathy (MN) is a primary glomerular disease commonly causing adult nephrotic syndrome. Characterized by thickened glomerular capillary walls due to immune complex deposition, MN is a complex autoimmune disorder. Its pathogenesis involves immune deposit formation, complement activation, and a heightened risk of renal failure. Central to MN is immune system dysfunction, particularly the dysregulation of B and T cell responses. B cells contribute to renal injury through the production of autoantibodies, particularly IgG targeting the phospholipase A2 receptor (PLA2R) on podocytes, while T cells modulate immune responses that influence disease progression. Metabolic reprogramming alters lymphocyte survival, differentiation, proliferation, and function, potentially triggering autoimmune processes. Although the link between immune cell metabolism and MN remains underexplored, this review highlights recent advances in understanding immune metabolism and its role in MN. These insights may provide novel biomarkers and therapeutic strategies for MN treatment.

Natural killer cells are decreased in systemic sclerosis and have diagnostic value for pulmonary arterial hypertension incorporation

The aim of this study was to investigate lymphocyte subsets, especially natural killer (NK) cells, in patients with systemic sclerosis (SSc) and evaluate the diagnostic value of NK cells in secondary pulmonary arterial hypertension (PAH). A total of 115 SSc patients and 100 age- and sex-matched health controls (HCs) were enrolled in this study. Flow cytometry was employed to quantify NK cells, while the association between NK cells and disease activity as well as PAH was investigated to further elucidate its diagnostic potential. The absolute count of NK (CD3-CD56+) cells significantly decreased in SSc patients. There was a negative correlation between the mRSS score and the injury index. The levels of cytokine exhibited significant elevation among SSc patients. Conversely, SSc-PAH patients demonstrated significantly elevated levels of CRP, UA, and BNP. Additionally, there was a significant reduction in the absolute level of NK cells. ROC curve analysis revealed that the optimal cut-off point for NK cells was 185 cells/µL, while for BNP it was 70.50 pg/mL and for UA it was 323.00 µmol/L. Our study revealed a significant inverse correlation between peripheral blood NK cell levels and the incidence of complicated PAH in patients with SSc.

Blood biomarker dynamics in people with relapsing multiple sclerosis treated with cladribine tablets: results of the 2-year MAGNIFY-MS study

Background and objectives

Cladribine tablets (CladT) represent an effective immune reconstitution therapy, administered in short treatment courses over two consecutive years. To better understand the amplitude of immune changes, we performed a comprehensive analysis during the 2-year study period for the entire MAGNIFY-MS population (N=270). In addition to lymphocyte kinetics, we studied intracellular cytokines serum proteins, and their associations with clinical outcomes. To put these changes into perspective, we analyzed transcriptional changes in T and B cells and associated biological pathways before and after each treatment course with CladT.

Methods

Immunophenotyping and transcriptomics were performed at regular visits with major differences reported between baseline (BL) and after each yearly treatment course. Assessments included: lymphocyte dynamics, RNA sequencing (B and T cells), intracellular cytokines, serum proteins (immunoglobulins [IgG and IgM], and serum neurofilament light chain [sNfL]). Clinical measures included: MRI activity, annualized relapse rate (ARR), 6-month confirmed disability progression (6mCDP), timed 25-foot walk (T25FW), and 9-hole peg test (9HPT).

Results

All B, T and NK cells were reduced at month (M)3 after CladT administration, except regulatory B cells which increased above BL from M3 to M24. Naïve and transitional B cells recovered at M6; all other B and T cell subsets remained below BL levels. Reductions in all NK cell subtypes were observed at M3, CD16lowCD56bright and NKp46 cells reconstituted at M6 and M12 respectively. Changes in genes and pathways associated with innate and adaptive immune response were observed after CladT treatment, along with reductions in pro-inflammatory cytokine-producing B and T cells and increases in anti-inflammatory cytokine-producing T cells. IgG and IgM levels remained above the lower limits of normal in most participants. sNfL levels decreased, remaining reduced by M24. Significant reductions in the annualized combined unique active lesion count occurred from M2 onwards. ARR was 0.11 (95% confidence interval: 0.09,0.15), with 83% participants free of qualifying relapses. Over 90% of participants were free of 6mCDP, around 87% had no confirmed progression on T25FW and 9HPT. No significant correlations were seen between clinical parameters and lymphocyte dynamics to M6. The safety profile was consistent with previous reports.

Discussion

Deep longitudinal immunophenotyping, analysis of transcriptional changes, reduction in cells expressing pro-inflammatory cytokines, along with the marker of neuroaxonal damage provide novel and innovative evidence of CladT rebalancing the immune system towards a more homeostatic and less pathogenic state.

Clinical Trial Registration

https://clinicaltrials.gov/study/, identifier NCT03364036.

Natural Killer Cells in Graves' Disease: Increased Frequency but Impaired Degranulation Ability Compared to Healthy Controls

Graves' disease (GD) is an autoimmune disorder, driven by the appearance of circulating autoantibodies (Ab) against the thyroid stimulating hormone (TSH) receptor, thus causing hyperthyroidism. While antithyroid drugs, the only available treatment for GD, carry a significant risk of relapse, advances in immunology could pave the way for more effective therapies. Natural killer (NK) cells, divided into cytotoxic CD56dim and cytokine-secreting CD56bright subsets, regulate immune responses through cytokine production and cell lysis and may play a role in the pathogenesis of GD. To investigate their involvement, we conducted flow cytometry on peripheral blood samples from 131 GD patients at various stages (disease onset, on antithyroid drugs, and in remission) and 97 age- and sex-matched healthy controls (HC). We analyzed NK cell subsets, activating (CD16, CD69, NKG2D, NKp30) and inhibitory receptors (CD161, NKG2A), degranulation (CD107a), and intracellular cytokines expression (interferon γ, tumor necrosis factor α). Statistical comparisons were made between GD patients and HC and across disease stages. GD patients had a higher frequency of total NK cells (p < 0.028) and CD56bright NK cells (p < 0.01) but a lower frequency of CD56dim NK cells (p = 0.005) compared to HC. NK cells in GD patients expressed activating receptors more frequently, except for NKG2D, but had decreased cytokine expression and degranulation ability. At GD onset, patients had higher frequencies of total NK cells, CD56bright NK cells, and NK cells expressing activating receptors compared to patients receiving ATD treatment and those in remission. CD161+ NK cells were lower at GD onset and returned to levels of HC following treatment. Correlation analysis revealed that free thyroxine (FT4) levels were inversely correlated with CD107a+ NK cells (p < 0.05) and positively correlated with CD69+ NK cells (p < 0.01). These findings suggest that hyperthyroidism impairs NK cell degranulation, with the increased frequency of NK cells potentially compensating for their reduced function. This dysfunction may contribute to the unregulated immune response in GD, highlighting NK cells as a potential target for novel therapeutic strategies.

Single-cell RNA sequencing uncovers molecular mechanisms of intravenous immunoglobulin plus methylprednisolone in Kawasaki disease: attenuated monocyte-driven inflammation and improved NK cell cytotoxicity

Introduction

Intravenous immunoglobulin (IVIG) plus methylprednisolone as initial intensive therapy or additional therapy in Kawasaki disease (KD) has been used in clinical practice. However, its molecular and cellular mechanism is unclear.

Methods

We performed single-cell analysis on 14 peripheral blood mononuclear cell (PBMC) samples obtained from 7 KD patients who received either IVIG monotherapy or IVIG plus methylprednisolone therapy. This encompassed 4 samples from KD patients collected before and after IVIG treatment, as well as 3 samples from KD patients before and after IVIG plus methylprednisolone therapy.

Results

Both IVIG monotherapy and IVIG plus methylprednisolone therapy can increase lymphocyte counts (e.g. CD4+T, CD8+T, and gdT cells) to address lymphopenia. They can also decrease monocyte counts and repress the expression of S100A12, NLRP3, and genes associated with immune-cell migration in monocytes. IVIG combined with methylprednisolone downregulates more monocyte-driven inflammatory pathways than IVIG alone. Additionally, this combination uniquely enhances NK cell cytotoxicity by modulating receptor homeostasis, while significantly upregulating interferon-related genes in CD4+ T cells, CD8+ T cells, and B cells, particularly type I interferons.

Conclusion

The combination of IVIG with methylprednisolone attenuated monocyte-driven inflammation and improved NK cell cytotoxicity which might provide clues for pediatricians to consider treatment options for children with KD. Whether the monocyte-driven hyperinflammatory state and NK cell function can be indicators for the clinical choice of IVIG with methylprednisolone therapy in KD needs further investigation.

Diagnostic use of circulating cells and sub-cellular bio-particles

In the bloodstream or other physiological fluids, "circulating cells and sub-cellular bio-particles" include many microscopic biological elements such as circulating tumor cells (CTCs), cell-free DNA (cfDNA), exosomes, microRNAs, platelets, immune cells, and proteins are the most well-known and investigated. These structures are crucial biomarkers in healthcare and medical research for the early detection of cancer and other disorders, enabling treatment to commence before the onset of clinical symptoms and enhancing the efficacy of treatments. As the size of these biomarkers to be detected decreases and their numbers in body fluids diminishes, the detection materials, ranging from visual inspection to advanced microscopy techniques, begin to become smaller, more sensitive, faster, and more effective, thanks to developing nanotechnology. This review first defines the circulating cells and subcellular bio-particles with their biological, physical, and mechanical properties and second focuses on their diagnostic importance, including their most recent applications as biomarkers, the biosensors that are utilized to detect them, the present obstacles that must be surmounted, and prospective developments in the domain. As technology advances and biomolecular pathways are deepens, diagnostic tests will become more sensitive, specific, and thorough. Finally, integrating recent advances in the diagnostic use of circulating cells and bioparticles into clinical practice is promising for precision medicine and patient outcomes.

The role of Killer immunoglobulin-like receptors (KIRs) in the genetic susceptibility to non-celiac wheat sensitivity (NCWS)

OBJECTIVES

Non-celiac wheat sensitivity (NCWS) is an emerging clinical condition characterized by gastrointestinal and extraintestinal symptoms following the ingestion of gluten-containing foods in patients without celiac disease (CD) or wheat allergy. Despite the great interest for NCWS, the genetic risk factors still need to be fully clarified. In this study, we first assessed the possible contribution of KIR genes and KIR haplotypes on the genetic predisposition to NCWS.

METHODS

Fifty patients with NCWS, 50 patients with CD, and 50 healthy controls (HC) were included in this study. KIR genes and KIR genotyping were investigated in all subjects by polymerase chain reaction with the sequence oligonucleotide probe (PCR-SSOP) method using Luminex technology.

RESULTS

We found a statistically different distribution of some KIR genes among NCWS, CD, and HC. Specifically, NCWS showed a decreased frequency of KIR2DL1, -2DL3, -2DL5, -2DS2, -2DS3, -2DS4, -2DS5, and -3DS1 genes, and an increased frequency of -3DL1 gene respect to both CD and HC. No difference was detected in the KIR haplotype expression. At the multivariate analysis, KIR2DL5, -2DS4, and -2DS5 were independent predictors of NCWS.

CONCLUSIONS

Our findings suggest a role of KIR genes in NCWS susceptibility, with KIR2DL5, -2DS4, and -2DS5 having a protective effect. Further large-scale multicentric studies are required to validate these preliminary findings.

Identification of Immune Gene Signature Associated with T Cells and Natural Killer Cells in Type 1 Diabetes

Purpose

This study aimed to investigate the abnormal infiltration of immune cells in type 1 diabetes mellitus (T1D) and elucidate their regulatory mechanisms.

Methods

Public T1D-related gene expression data were obtained from the Gene Expression Omnibus database.The GSE123658 dataset analyzed whole blood RNA-seq data from type 1 diabetic patients and healthy volunteers. The GSE110914 dataset analyzed neutrophils purified from peripheral blood of patients with symptomatic and pre-symptomatic type 1 diabetes (T1D), at risk of T1D, and healthy controls. Immune cell infiltration analysis was performed to identify abnormally infiltrating immune cells. Differentially expressed immune genes (DEIGs) in T1D samples were identified, followed by the construction of an immune gene signature (IGS) using a protein-protein interaction (PPI) network and Least absolute shrinkage and selection operator Cox regression analyses (LASSO Cox regression analyses). The regulatory mechanisms underlying IGS were explored using gene set enrichment analysis. Furthermore, expression validation, diagnostic efficacy evaluation, and upstream miRNA prediction of hub signature genes were performed. We verified the miRNA expression of the key gene colony stimulating factor 1 (CSF1) and microRNA-326 (miR-326) by reverse transcription-quantitative PCR (RT‒qPCR).

Results

The proportion of infiltrating T and natural killer (NK) cells differed between the T1D and control samples, and 207 immune genes (IGs) related to these immune cells were extracted. After differential expression, PPI, and LASSO Cox regression analyses, four signature DEIGs were identified for IGS construction: notch receptor 1 (NOTCH1), Janus kinase 3 (JAK3), tumor necrosis factor receptor superfamily member 4(TNFRSF4), and CSF1. Key pathways such as the Toll-like receptor signaling pathway were significantly activated in the high-risk group. Moreover, the upregulation of CSF1 in T1D samples was confirmed using a validation dataset, and CSF1 showed high diagnostic efficacy for T1D. Furthermore, CSF1 was targeted by miR-326.We used validated key genes in T1D patients, several of which were confirmed by RT‒qPCR.

Conclusion

In conclusion, the identified key IGs may play an important role in T1D. CSF1 can be developed as a novel diagnostic biomarker for T1D.

Natural killer cells in cancer immunotherapy

Natural killer (NK) cells, as innate lymphocytes, possess cytotoxic capabilities and engage target cells through a repertoire of activating and inhibitory receptors. Particularly, natural killer group 2, member D (NKG2D) receptor on NK cells recognizes stress-induced ligands-the MHC class I chain-related molecules A and B (MICA/B) presented on tumor cells and is key to trigger the cytolytic response of NK cells. However, tumors have developed sophisticated strategies to evade NK cell surveillance, which lead to failure of tumor immunotherapy. In this paper, we summarized these immune escaping strategies, including the downregulation of ligands for activating receptors, upregulation of ligands for inhibitory receptors, secretion of immunosuppressive compounds, and the development of apoptosis resistance. Then, we focus on recent advancements in NK cell immune therapies, which include engaging activating NK cell receptors, upregulating NKG2D ligand MICA/B expression, blocking inhibitory NK cell receptors, adoptive NK cell therapy, chimeric antigen receptor (CAR)-engineered NK cells (CAR-NK), and NKG2D CAR-T cells, especially several vaccines targeting MICA/B. This review will inspire the research in NK cell biology in tumor and provide significant hope for improving cancer treatment outcomes by harnessing the potent cytotoxic activity of NK cells.

Unveiling the Significance of HLA and KIR Diversity in Underrepresented Populations

Human leukocyte antigen (HLA) molecules and their relationships with natural killer (NK) cells, specifically through their interaction with killer-cell immunoglobulin-like receptors (KIRs), exhibit robust associations with the outcomes of diverse diseases. Moreover, genetic variations in HLA and KIR immune system genes offer limitless depths of complexity. In recent years, a surge of high-powered genome-wide association studies (GWASs) utilizing single nucleotide polymorphism (SNP) arrays has occurred, significantly advancing our understanding of disease pathogenesis. Additionally, advances in HLA reference panels have enabled higher resolution and more reliable imputation, allowing for finer-grained evaluation of the association between sequence variations and disease risk. However, it is essential to note that the majority of these GWASs have focused primarily on populations of Caucasian and Asian origins, neglecting underrepresented populations in Latin America and Africa. This omission not only leads to disparities in health care access but also restricts our knowledge of novel genetic variants involved in disease pathogenesis within these overlooked populations. Since the KIR and HLA haplotypes prevalent in each population are clearly modelled by the specific environment, the aim of this review is to encourage studies investigating HLA/KIR involvement in infection and autoimmune diseases, reproduction, and transplantation in underrepresented populations.

The shared circulating diagnostic biomarkers and molecular mechanisms of systemic lupus erythematosus and inflammatory bowel disease

Background

Systemic lupus erythematosus (SLE) is a multi-organ chronic autoimmune disease. Inflammatory bowel disease (IBD) is a common chronic inflammatory disease of the gastrointestinal tract. Previous studies have shown that SLE and IBD share common pathogenic pathways and genetic susceptibility, but the specific pathogenic mechanisms remain unclear.

Methods

The datasets of SLE and IBD were downloaded from the Gene Expression Omnibus (GEO). Differentially expressed genes (DEGs) were identified using the Limma package. Weighted gene coexpression network analysis (WGCNA) was used to determine co-expression modules related to SLE and IBD. Pathway enrichment was performed using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis for co-driver genes. Using the Least AbsoluteShrinkage and Selection Operator (Lasso) regressionand Support Vector Machine-Recursive Feature Elimination (SVM-RFE), common diagnostic markers for both diseases were further evaluated. Then, we utilizedthe CIBERSORT method to assess the abundance of immune cell infiltration. Finally,we used the single-cell analysis to obtain the location of common diagnostic markers.

Results

71 common driver genes were identified in the SLE and IBD cohorts based on the DEGs and module genes. KEGG and GO enrichment results showed that these genes were closely associated with positive regulation of programmed cell death and inflammatory responses. By using LASSO regression and SVM, five hub genes (KLRF1, GZMK, KLRB1, CD40LG, and IL-7R) were ultimately determined as common diagnostic markers for SLE and IBD. ROC curve analysis also showed good diagnostic performance. The outcomes of immune cell infiltration demonstrated that SLE and IBD shared almost identical immune infiltration patterns. Furthermore, the majority of the hub genes were commonly expressed in NK cells by single-cell analysis.

Conclusion

This study demonstrates that SLE and IBD share common diagnostic markers and pathogenic pathways. In addition, SLE and IBD show similar immune cellinfiltration microenvironments which provides newperspectives for future treatment.

Identifying the genetic association between systemic lupus erythematosus and the risk of autoimmune liver diseases

BACKGROUND

Previous studies on the relationship between systemic lupus erythematosus (SLE) and autoimmune liver diseases (AILDs) are inconclusive. Therefore, we employed Mendelian randomization (MR) to explore the causal associations between SLE and AILDs.

METHODS

A two-sample MR analysis was performed using summary-level statistics sourced from genome-wide association study (GWAS) datasets. Inverse-variance weighting (IVW), MR‒Egger, and weighted median (WM) were further supported by several sensitivity analyses.

RESULTS

We detected causal genetic associations between SLE and primary biliary cholangitis (PBC) (odds ratio (OR) = 1.31, 95% CI = 1.15-1.51, P < 0.01; adjusted OR = 1.63, 95% CI = 1.39-1.90, P < 0.01) and between SLE and primary sclerosing cholangitis (PSC) (OR = 1.09, 95% CI = 1.01-1.08, P = 0.03; adjusted OR = 1.10, 95% CI = 1.00-1.21, P = 0.04). No causal association was found between SLE and autoimmune hepatitis.

CONCLUSIONS

We are the first to use MR analysis to explore the causal relationships between SLE and various AILDs, revealing an increased risk of PBC and PSC in individuals with SLE.

Ozanimod-mediated remission in experimental autoimmune encephalomyelitis is associated with enhanced activity of CNS CD27low/- NK cell subset

Background

Ozanimod (RPC1063) is an immunomodulator that has been recently approved by the FDA (2020) for the treatment of relapsing-remitting multiple sclerosis (RRMS). It is a selective agonist of the sphingosine-1-phophate receptors 1 and 5, expressed on naïve and central memory T and B cells, as well as natural killer (NK) cells, and is involved in lymphocyte trafficking. Oral administration of ozanimod was reported to result in rapid and reversible reduction in circulating lymphocytes in multiple sclerosis (MS) patients, however, only minimal effect on NK cells was observed. In this study, we sought to investigate the effect of ozanimod on NK cells and assess whether they play any role in ozanimod-induced remission in experimental autoimmune encephalomyelitis (EAE), the animal model of MS.

Methods

Active EAE induction was done in C57BL/6 female mice, followed by daily oral treatment with ozanimod (0.6mg/kg) starting at disease onset (score 1). Flow cytometry of blood and CNS was performed 24 hours after the last oral dose of ozanimod treatment in diseased mice. Histological analysis of lumbar spinal cord was performed for evaluating the level of inflammation and demyelination. Depletion of peripheral NK cells was done using anti-NK1.1 mouse antibody (mAb) at day 5 post-EAE induction.

Results

Ozanimod was effective in reducing the clinical severity of EAE and reducing the percentage of autoreactive CD4+ and CD8+ T cells along with significant inhibition of lymphocyte infiltration into the spinal cord, accompanied by reversed demyelination. Furthermore, ozanimod treatment resulted in a significant increase in the frequency of total NK cells in the blood and CNS along with upregulation of the activating receptor NKG2D on CD27low/- NK cell subset in the CNS. The effectiveness of ozanimod treatment in inhibiting the progression of the disease was reduced when NK cells were depleted using anti-NK1.1 mAb.

Conclusion

The current study demonstrated that ozanimod treatment significantly improved clinical symptoms in EAE mice. Ozanimod and anti-NK1.1 mAb appear to function in opposition to one another. Collectively, our data suggest that ozanimod-mediated remission is associated with an increased percentage of total NK cells and CD27low/- NK cells expressing the activating receptor, NKG2D in the CNS.

Increased CD8+ tissue resident memory T cells, regulatory T cells and activated natural killer cells in systemic sclerosis lungs

OBJECTIVE

Multiple observations indicate a role for lymphocytes in driving autoimmunity in SSc. While T and NK cells have been studied in SSc whole blood and bronchoalveolar lavage fluid, their role remains unclear, partly because no studies have analysed these cell types in SSc-interstitial lung disease (ILD) lung tissue. This research aimed to identify and analyse the lymphoid subpopulations in SSc-ILD lung explants.

METHODS

Lymphoid populations from 13 SSc-ILD and 6 healthy control (HC) lung explants were analysed using Seurat following single-cell RNA sequencing. Lymphoid clusters were identified by their differential gene expression. Absolute cell numbers and cell proportions in each cluster were compared between cohorts. Additional analyses were performed using pathway analysis, pseudotime and cell ligand-receptor interactions.

RESULTS

Activated CD16+ NK cells, CD8+ tissue resident memory T cells and Treg cells were proportionately higher in SSc-ILD compared with HC lungs. Activated CD16+ NK cells in SSc-ILD showed upregulated granzyme B, IFN-γ and CD226. Amphiregulin, highly upregulated by NK cells, was predicted to interact with epidermal growth factor receptor on several bronchial epithelial cell populations. Shifts in CD8+ T cell populations indicated a transition from resting to effector to tissue resident phenotypes in SSc-ILD.

CONCLUSIONS

SSc-ILD lungs show activated lymphoid populations. Activated cytotoxic NK cells suggest they may kill alveolar epithelial cells, while their expression of amphiregulin suggests they may also induce bronchial epithelial cell hyperplasia. CD8+ T cells in SSc-ILD appear to transition from resting to the tissue resident memory phenotype.

Natural killer cell-mediated immune surveillance in cancer: Role of tumor microenvironment

In the immunological surveillance against cancer, natural killer (NK) cells are essential effectors that help eradicate altered cells. The complex interactions that occur between NK cells and the tumor microenvironment (TME) are thoroughly examined in this review. The review examines how cytokine stimulation affects NK cell activation, focusing on the dynamic modulation of NK cell function within the TME. It looks at NK cell-related biomarkers such as PD-1/PD-L1, methylation HOXA9 (Homeobox A9), Stroma AReactive Invasion Front Areas (SARIFA), and NKG2A/HLA-E, providing critical information about prognosis and treatment outcomes. The changing landscape of immunotherapies-including checkpoint inhibitors, CAR-NK cells, and cytokine-based interventions-is examined in the context of enhancing NK cell activity. The review highlights the potential pathways for precision medicine going forward, focusing on customized immunotherapies based on unique biomarker profiles and investigating combination medicines to produce more robust anti-tumor responses.

Microglia and Systemic Immunity

Microglia are specialized immune cells that reside in the central nervous system (CNS) and play a crucial role in maintaining the homeostasis of the brain microenvironment. While traditionally regarded as a part of the innate immune system, recent research has highlighted their role in adaptive immunity. The CNS is no longer considered an immune-privileged organ, and increasing evidence suggests bidirectional communication between the immune system and the CNS. Microglia are sensitive to systemic immune signals and can respond to systemic inflammation by producing various inflammatory cytokines and chemokines. This response is mediated by activating pattern recognition receptors (PRRs), which recognize pathogen- and danger-associated molecular patterns in the systemic circulation. The microglial response to systemic inflammation has been implicated in several neurological conditions, including depression, anxiety, and cognitive impairment. Understanding the complex interplay between microglia and systemic immunity is crucial for developing therapeutic interventions to modulate immune responses in the CNS.

Natural killer cells immunosenescence and the impact of lifestyle management

Natural killer cells (NKs) are lymphocytes of the innate immune system that quickly respond to viruses, infections, and tumors during their short cell life cycle. However, it was recently found that NKs undergo quantitative, distributional, structural, and functional phenotypic changes during aging that suppress immune responses, which is known as immunosenescence. The aging host environment, cytokine regulation, cytomegalovirus status, and hypothalamic‒pituitary‒adrenal axis have significant effects on NK function. Different lifestyle management interventions modulate the number and cytotoxic activity of NKs, which are essential for rebuilding the immune barrier against pathogens in elderly individuals. Based on recent studies, we review the phenotypic changes of and potential threats of NKs during aging and explore the underlying mechanisms. By summarizing the effects of lifestyle management on NKs and their application prospects, we aim to provide evidence for enhancing immune system function against immune diseases in elderly individuals.

Using the power of innate immunoprofiling to understand vaccine design, infection, and immunity

In the field of immunology, a systems biology approach is crucial to understanding the immune response to infection and vaccination considering the complex interplay between genetic, epigenetic, and environmental factors. Significant progress has been made in understanding the innate immune response, including cell players and critical signaling pathways, but many questions remain unanswered, including how the innate immune response dictates host/pathogen responses and responses to vaccines. To complicate things further, it is becoming increasingly clear that the innate immune response is not a linear pathway but is formed from complex networks and interactions. To further our understanding of the crosstalk and complexities, systems-level analyses and expanded experimental technologies are now needed. In this review, we discuss the most recent immunoprofiling techniques and discuss systems approaches to studying the global innate immune landscape which will inform on the development of personalized medicine and innovative vaccine strategies.

MICa/b-dependent activation of natural killer cells by CD64+ inflammatory type 2 dendritic cells contributes to autoimmunity

Primary Sjögren's syndrome (pSS) is an inflammatory autoimmune disorder largely mediated by type I and II interferon (IFN). The potential contribution of innate immune cells, such as natural killer (NK) cells and dendritic cells (DC), to the pSS pathology remains understudied. Here, we identified an enriched CD16+ CD56hi NK cell subset associated with higher cytotoxic function, as well as elevated proportions of inflammatory CD64+ conventional dendritic cell (cDC2) subtype that expresses increased levels of MICa/b, the ligand for the activating receptor NKG2D, in pSS individuals. Circulating cDC2 from pSS patients efficiently induced activation of cytotoxic NK cells ex vivo and were found in proximity to CD56+ NK cells in salivary glands (SG) from pSS patients. Interestingly, transcriptional activation of IFN signatures associated with the RIG-I/DDX60 pathway, IFN I receptor, and its target genes regulate the expression of NKG2D ligands on cDC2 from pSS patients. Finally, increased proportions of CD64hi RAE-1+ cDC2 and NKG2D+ CD11b+ CD27+ NK cells were present in vivo in the SG after poly I:C injection. Our study provides novel insight into the contribution and interplay of NK and cDC2 in pSS pathology and identifies new potential therapy targets.

Molecular and Cellular Insights: A Focus on Glycans and the HNK1 Epitope in Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a synaptic disorder with a GABA/glutamate imbalance in the perineuronal nets and structural abnormalities such as increased dendritic spines and decreased long distance connections. Specific pregnancy disorders significantly increase the risk for an ASD phenotype such as preeclampsia, preterm birth, hypoxia phenomena, and spontaneous miscarriages. They are associated with defects in the glycosylation-immune placental processes implicated in neurogenesis. Some glycans epitopes expressed in the placenta, and specifically in the extra-villous trophoblast also have predominant functions in dendritic process and synapse function. Among these, the most important are CD57 or HNK1, CD22, CD24, CD33 and CD45. They modulate the innate immune cells at the maternal-fetal interface and they promote foeto-maternal tolerance. There are many glycan-based pathways of immunosuppression. N-glycosylation pathway dysregulation has been found to be associated with autoimmune-like phenotypes and maternal-autoantibody-related (MAR) autism have been found to be associated with central, systemic and peripheric autoimmune processes. Essential molecular pathways associated with the glycan-epitopes expression have been found to be specifically dysregulated in ASD, notably the Slit/Robo, Wnt, and mTOR/RAGE signaling pathways. These modifications have important effects on major transcriptional pathways with important genetic expression consequences. These modifications lead to defects in neuronal progenitors and in the nervous system's implementation specifically, with further molecular defects in the GABA/glutamate system. Glycosylation placental processes are crucial effectors for proper maternofetal immunity and endocrine/paracrine pathways formation. Glycans/ galectins expression regulate immunity and neurulation processes with a direct link with gene expression. These need to be clearly elucidated in ASD pathophysiology.

The Molecular Role of Immune Cells in Dilated Cardiomyopathy

Dilated cardiomyopathy (DCM) is a rare and severe condition characterized by chamber dilation and impaired contraction of the left ventricle. It constitutes a fundamental etiology for profound heart failure and abrupt cardiac demise, rendering it a prominent clinical indication for heart transplantation (HTx) among both adult and pediatric populations. DCM arises from various etiologies, including genetic variants, epigenetic disorders, infectious insults, autoimmune diseases, and cardiac conduction abnormalities. The maintenance of cardiac function involves two distinct types of immune cells: resident immune cells and recruited immune cells. Resident immune cells play a crucial role in establishing a harmonious microenvironment within the cardiac tissue. Nevertheless, in response to injury, cardiomyocytes initiate a cytokine cascade that attracts peripheral immune cells, thus perturbing this intricate equilibrium and actively participating in the initiation and pathological remodeling of dilated cardiomyopathy (DCM), particularly during the progression of myocardial fibrosis. Additionally, immune cells assume a pivotal role in orchestrating the inflammatory processes, which are intimately linked to the prognosis of DCM. Consequently, understanding the molecular role of various immune cells and their regulation mechanisms would provide an emerging era for managing DCM. In this review, we provide a summary of the most recent advancements in our understanding of the molecular mechanisms of immune cells in DCM. Additionally, we evaluate the effectiveness and limitations of immunotherapy approaches for the treatment of DCM, with the aim of optimizing future immunotherapeutic strategies for this condition.

Myc controls NK cell development, IL-15-driven expansion, and translational machinery

MYC is a pleiotropic transcription factor involved in cancer, cell proliferation, and metabolism. Its regulation and function in NK cells, which are innate cytotoxic lymphocytes important to control viral infections and cancer, remain poorly defined. Here, we show that mice deficient for Myc in NK cells presented a severe reduction in these lymphocytes. Myc was required for NK cell development and expansion in response to the key cytokine IL-15, which induced Myc through transcriptional and posttranslational mechanisms. Mechanistically, Myc ablation in vivo largely impacted NK cells' ribosomagenesis, reducing their translation and expansion capacities. Similar results were obtained by inhibiting MYC in human NK cells. Impairing translation by pharmacological intervention phenocopied the consequences of deleting or blocking MYC in vitro. Notably, mice lacking Myc in NK cells exhibited defective anticancer immunity, which reflected their decreased numbers of mature NK cells exerting suboptimal cytotoxic functions. These results indicate that MYC is a central node in NK cells, connecting IL-15 to translational fitness, expansion, and anticancer immunity.

Exploration of KIR genes and hematological-related diseases in Chinese Han population

The function of natural killer (NK) cells has previously been implicated in hematopoietic-related diseases. Killer immunoglobulin-like receptors (KIR) play an important role in NK cells after hematopoietic stem cell transplantation. To explore the immunogenetic predisposition of hematological-related diseases, herein, a multi-center retrospective study in China was conducted, analyzing and comparing 2519 patients with hematopathy (mainly, acute lymphoblastic leukemia, acute myeloid leukemia, aplastic anemia, and myelodysplastic syndrome) to 18,108 individuals without known pathology. Genotyping was performed by polymerase chain reaction with specific sequence primers (PCR-SSP). As a result, we discovered four genes including KIR2DL5 (OR: 0.74, 95% CI 0.59-0.93; Pc = 0.0405), 2DS1 (OR: 0.74, 95% CI 0.59-0.93; Pc = 0.0405), 2DS3 (OR: 0.58, 95% CI 0.41-0.81; Pc = 0.0180), and 3DS1 (OR: 0.74, 95% CI 0.58-0.94; Pc = 0.0405) to be protective factors that significantly reduce the risk of aplastic anemia. Our findings offer new approaches to immunotherapy for hematological-related diseases. As these therapies mature, they are promising to be used alone or in combination with current treatments to help to make blood disorders a manageable disease.

Natural killer cell epigenetic reprogramming in tumors and potential for cancer immunotherapy

Natural killer (NK) cells are critical members of the innate lymphoid cell population and have a pivotal role in cancer eradication. NK cell maturation, development and function are tightly regulated by epigenetic modifications, which can also be recruited for cancer propagation and immune escape. NK cells have the potential to be activated against tumors through several epigenetic regulators. Given that epigenetic changes are inducible and reversible, focusing on aberrant epigenetic regulations recruited by tumor cells provides a tremendous opportunity for cancer treatment. This review presents a comprehensive picture of NK cell normal epigenetic regulation and cancer-driven epigenetic modifications. From our perspective, a better understanding of epigenetic regulators that can edit and revise NK cells' activity is a promising avenue for NK cell-based therapy in cancer management.

Immune characterization of a xenogeneic human lung cross-circulation support system

Improved approaches to expanding the pool of donor lungs suitable for transplantation are critically needed for the growing population with end-stage lung disease. Cross-circulation (XC) of whole blood between swine and explanted human lungs has previously been reported to enable the extracorporeal recovery of donor lungs that declined for transplantation due to acute, reversible injuries. However, immunologic interactions of this xenogeneic platform have not been characterized, thus limiting potential translational applications. Using flow cytometry and immunohistochemistry, we demonstrate that porcine immune cell and immunoglobulin infiltration occurs in this xenogeneic XC system, in the context of calcineurin-based immunosuppression and complement depletion. Despite this, xenogeneic XC supported the viability, tissue integrity, and physiologic improvement of human donor lungs over 24 hours of xeno-support. These findings provide targets for future immunomodulatory strategies to minimize immunologic interactions on this organ support biotechnology.

Immunostaining of stromal CD56 cells in ovarian malignancies

OBJECTIVES

The aim of this study was to evaluate CD56 immunostaining in the stroma of benign and malignant ovarian epithelial neoplasms and associate the CD56 immunostaining with prognostic factors and survival in ovarian cancer.

METHODS

Patients with ovarian epithelial neoplasia (n=77) were studied with a prospective cohort. The CD56 immunostaining was evaluated in the peritumoral stroma. Two groups were evaluated: benign ovarian neoplasms (n=40) and malignant ovarian neoplasms (n=37). Data were recorded for histological type and grade, International Federation of Gynecology and Obstetrics staging, molecular subtype, and lymph node metastases. Fisher's exact test and Kaplan-Meier survival curves were used, with a significance level of ≤0.05.

RESULTS

We found greater CD56 stromal immunostaining in malignant neoplasms when compared to the group of benign neoplasms (p=0.00001). There was no significant difference in relation to the prognostic factors and survival.

CONCLUSION

Malignant ovarian neoplasms showed higher stromal CD56 immunostaining. As the prognostic value of natural killer in ovarian cancer is controversial, knowing the specific function of each cell present both in the tumor tissue and systemically may help guide successful immunotherapies in the near future.

Lower percentages of natural killer cells in children with type 1 diabetes and their siblings

INTRODUCTION

One of the most common children's endocrine and autoimmune diseases in the world is type 1 diabetes mellitus (T1DM). The incidence of type 1 diabetes is constantly increasing, and according to current estimates, the number of children with T1DM in the world has exceeded 542,000. There are 3 main components emphasized in the pathogenesis: genetic and environmental factors, and the patient's immune system. Many publications have confirmed the role of natural killer cells (NK) in the pathogenesis of type 1 diabetes and other autoimmune diseases.

AIM

The aim of the study was to evaluate the population of NK cells and pancreatic β cell autoantibodies in a group of children with T1DM and their healthy siblings in comparison with children from families with no history of autoimmune diseases.

MATERIAL AND METHODS

The research included 76 children with T1DM, 101 children from the sibling group, and 30 children from the control group. Peripheral blood was analysed on a FACSCalibur flow cytometer (Becton Dickinson) to evaluate the NK cell population. The results were presented as the percentage of NK cells among lymphocytes. Statistical analysis was performed using STATIS-TICA 10 PL software.

RESULTS

The mean percentage of NK cells in children with T1D (10.59 ±5.37) and in the sibling group (11.93 ±5.62) was statistically reduced in comparison to the control group (14.89 ±7.78) in sequence (Student's t -test: t = -3.24; df = 103; p = 0.002) (Stu-dent's t -test: t = -2.30; df = 128; p = 0.02). There was no statistically significant difference in the percentage of NK cells be-tween the group of children with T1DM and their siblings (Student's t -test: t = -1.59; df = 173; p = 0.11). In the group of sib-lings, the younger the child, the lower the reported percentage of NK cells. This relationship was statistically significant (test for the Pearson correlation coefficient t = 3.41; p = 0.0009; r = 0.33). In the group of children with type 1 diabetes, a similar relationship was not found. The concentration of anti-IA2 and anti-Znt8 antibodies was statistically significantly higher in the sibling group compared to the control group (anti-IA2 p = 0.0000001; anti-ZnT8 p = 0.00001), and the concentration of anti-GAD antibodies was comparable in both groups. In the group of children with type 1 diabetes, a positive correlation was demonstrated between the reduced percentage of NK cells and the coexistence of anti-GAD and anti-ZnT8 antibodies (Mann-Whitney U test Z = -2.02; p = 0.04). There was no similar relationship in the group of siblings.

CONCLUSIONS

The reduced percentage of NK cells in children with T1DM and in their siblings compared to the control group suggests the role of NK cells in the pathogenesis of T1DM. Genetic predisposition and dysfunction of NK cells probably underlie the pathogenesis of T1DM.

Increased expression of the ectoenzyme CD38 in peripheral blood plasmablasts and plasma cells of patients with systemic sclerosis

Objective

CD38 is a type II glycoprotein highly expressed on plasmablasts and on short- and long-lived plasma cells, but weakly expressed by lymphoid, myeloid, and non-hematopoietic cells. CD38 is a target for therapies aimed at depleting antibody-producing plasma cells. Systemic sclerosis (SSc) is an immune-mediated disease with a well-documented pathogenic role of B cells. We therefore analyzed CD38 expression in different subsets of peripheral blood mononuclear cells (PBMCs) from a cohort of SSc patients.

Methods

Cell surface expression of CD38 was evaluated on PBMCs from SSc patients using eight-color flow cytometry analysis performed with a FacsCanto II (BD). Healthy individuals were used as controls (HC).

Results

Forty-six SSc patients (mean age 56, range 23-79 years; 38 females and 8 males), and thirty-two age- and sex-matched HC were studied. Twenty-eight patients had the limited cutaneous form and eighteen the diffuse cutaneous form of SSc. The mean disease duration was 7 years. Fourteen patients were on immunosuppressive therapy (14 MMF, 5 RTX). The total percentages of T, B and NK cells were not different between SSc and HC. Compared to HC, SSc patients had higher levels of CD3+CD38+ T cells (p<0.05), higher percentage (p<0.001) of CD3+CD4+CD25+FOXP3+ regulatory T cells, lower percentage (p<0.05) of CD3+CD56+ NK T cells. Moreover, SSc patients had higher levels of CD24^highCD19+CD38^high regulatory B cells than HC (p<0.01), while the amount of CD24+CD19+CD38+CD27+ memory B cells was lower (p<0.001). Finally, the percentages of circulating CD38^highCD27+ plasmablasts and CD138+CD38^high plasma cells were both higher in the SSc group than in HC (p<0.001). We did not observe any correlations between these immunophenotypes and disease subsets or duration, and ongoing immunosuppressive treatment.

Conclusions

The increased expression of CD38 in peripheral blood plasmablasts and plasma cells of SSc patients may suggest this ectoenzyme as a candidate therapeutic target, under the hypothesis that depletion of these cells may beneficially downregulate the chronic immune response in SSc patients. Validation of this data in multicenter cohorts shall be obtained prior to clinical trials with existing anti-CD38 drugs.

Exploiting the role of T cells in the pathogenesis of Sjögren's syndrome for therapeutic treatment

Sjögrens syndrome (SS) is caused by autoantibodies that attack proprioceptive salivary and lacrimal gland tissues. Damage to the glands leads to dry mouth and eyes and affects multiple systems and organs. In severe cases, SS is life-threatening because it can lead to interstitial lung disease, renal insufficiency, and lymphoma. Histological examination of the labial minor salivary glands of patients with SS reveals focal lymphocyte aggregation of T and B cells. More studies have been conducted on the role of B cells in the pathogenesis of SS, whereas the role of T cells has only recently attracted the attention of researchers. This review focusses on the role of various populations of T cells in the pathogenesis of SS and the progress made in research to therapeutically targeting T cells for the treatment of patients with SS.

Studying the Interactions of U24 from HHV-6 in Order to Further Elucidate Its Potential Role in MS

A number of studies have suggested that human herpesvirus 6A (HHV-6A) may play a role in multiple sclerosis (MS). Three possible hypotheses have been investigated: (1) U24 from HHV-6A (U24-6A) mimics myelin basic protein (MBP) through analogous phosphorylation and interaction with Fyn-SH3; (2) U24-6A affects endocytic recycling by binding human neural precursor cell (NPC) expressed developmentally down-regulated protein 4-like WW3* domain (hNedd4L-WW3*); and (3) MS patients who express Killer Cell Immunoglobulin Like Receptor 2DL2 (KIR2DL2) on natural killer (NK) cells are more susceptible to HHV-6 infection. In this contribution, we examined the validity of these propositions by investigating the interactions of U24 from HHV-6B (U24-6B), a variant less commonly linked to MS, with Fyn-SH3 and hNedd4L-WW3* using heteronuclear single quantum coherence (HSQC) nuclear magnetic resonance (NMR) titrations and isothermal titration calorimetry (ITC). In addition, the importance of phosphorylation and the specific role of U24 in NK cell activation in MS patients were examined. Overall, the findings allowed us to shed light into the models linking HHV-6 to MS and the involvement of U24.

Disturbed natural killer cell homeostasis in the salivary gland enhances autoimmune pathology via IFN-γ in a mouse model of primary Sjögren's syndrome

OBJECTIVE

Innate lymphoid cells (ILCs), including natural killer (NK) cells, ILC1, ILC2, lymphoid tissue-inducer (LTi) cells, and ILC3 cell, play a key role in various immune responses. Primary Sjögren's syndrome (pSS) is an autoimmune disease characterized by chronic inflammation of exocrine glands, such as the lacrimal and salivary glands (SGs). The role of NK cells among ILCs in the pathogenesis of pSS is still unclear. In this study, the characteristics and subsets of NK cells in the salivary gland (SG) tissue were analyzed using a murine model of pSS.

METHODS

Multiple phenotypes and cytotoxic signature of the SG NK cells in control and pSS model mice were evaluated by flow cytometric analysis. Intracellular expression of interferon-γ (IFN-γ) among T cells and NK cells from the SG tissues was compared by in vitro experiments. In addition, pathological analysis was performed using anti-asialo-GM1 (ASGM1) antibody (Ab)-injected pSS model mice.

RESULTS

The number of conventional NK (cNK) cells in the SG of pSS model mice significantly increased compared with that in control mice at 6 weeks of age. The production level of IFN-γ was significantly higher in SG NK cells than in SG T cells. The depletion of NK cells by ASGM1 Ab altered the ratio of tissue resident NK (rNK) cells to cNK cells, which inhibited the injury to SG cells with the recovery of saliva secretion in pSS model mice.

CONCLUSION

The results indicate that SG cNK cells may enhance the autoreactive response in the target organ by upregulating of IFN-γ, whereas SG rNK cells protect target cells against T cell cytotoxicity. Therefore, the activation process and multiple functions of NK cells in the target organ could be helpful to develop potential markers for determining autoimmune disease activity and target molecules for incurable immune disorders.

Implications of NKG2A in immunity and immune-mediated diseases

In recent studies, NKG2A is revealed to be a key immune checkpoint for both natural killer (NK) cells and CD8⁺ T cells. It form heterodimer receptors with CD94, and targets the peptide-presenting human leukocyte antigen-E (HLA-E) molecules. Upon crosslinking, NKG2A/CD94 delivers inhibitory signals for NK cells and CD8⁺ T cells, while blocking NKG2A can effectively unleash functions of these cytotoxic lymphocytes. The interaction between NKG2A and HLA-E contributes to tumor immune escape, and NKG2A-mediated mechanisms are currently being exploited to develop potential antitumor therapeutic strategies. In addition, growing evidence shows that NKG2A also plays important roles in other immune-related diseases including viral infections, autoimmune diseases, inflammatory diseases, parasite infections and transplant rejection. Therefore, the current work focuses on describing the effect of NKG2A on immune regulation and exploring its potential role in immune-mediated disorders.

Natural Killer Cells in Multiple Sclerosis: Entering the Stage

Studies investigating the immunopathology of multiple sclerosis (MS) have largely focused on adaptive T and B lymphocytes. However, in recent years there has been an increased interest in the contribution of innate immune cells, amongst which the natural killer (NK) cells. Apart from their canonical role of controlling viral infections, cell stress and malignancies, NK cells are increasingly being recognized for their modulating effect on the adaptive immune system, both in health and autoimmune disease. From different lines of research there is now evidence that NK cells contribute to MS immunopathology. In this review, we provide an overview of studies that have investigated the role of NK cells in the pathogenesis of MS by use of the experimental autoimmune encephalomyelitis (EAE) animal model, MS genetics or through ex vivo and in vitro work into the immunology of MS patients. With the advent of modern hypothesis-free technologies such as single-cell transcriptomics, we are exposing an unexpected NK cell heterogeneity, increasingly blurring the boundaries between adaptive and innate immunity. We conclude that unravelling this heterogeneity, as well as the mechanistic link between innate and adaptive immune cell functions will lay the foundation for the use of NK cells as prognostic tools and therapeutic targets in MS and a myriad of other currently uncurable autoimmune disorders.

Glucocorticoids and natural killer cells: A suppressive relationship

Glucocorticoids exert their pharmacological actions by mimicking and amplifying the function of the endogenous glucocorticoid system's canonical physiological stress response. They affect the immune system at the levels of inflammation and adaptive and innate immunity. These effects are the basis for therapeutic use of glucocorticoids. Innate immunity is the body's first line of defense against disease conditions. It is relatively nonspecific and, among its mediators, natural killer (NK) cells link innate and acquired immunity. NK cell numbers are altered in patients with auto immune diseases, and research suggests that interactions between glucocorticoids and natural killer cells are critical for successful glucocorticoid therapy. The aim of this review is to summarize these interactions while highlighting the latest and most important developments in this field. Production and release in the blood of endogenous glucocorticoids are strictly regulated by the hypothalamus-pituitary adrenal axis. A self-regulatory mechanism prevents excessive plasma levels of these hormones. However, exogenous stimuli such as stress, inflammation, infections, cancer, and autoimmune disease can trigger the hypothalamus-pituitary-adrenal axis response and lead to excessive systemic release of glucocorticoids. Thus, stress stimuli, such as sleep deprivation, intense exercise, depression, viral infections, and cancer, can result in release of glucocorticoids and associated immunosuppressant effects. Among these effects are decreases in the numbers and activities of NK cells in inflammatory and autoimmune diseases (e.g., giant cell arteritis, polymyalgia rheumatica, and familial hypogammaglobulinemia).

Photophosphatidylserine Guides Natural Killer Cell Photoimmunotherapy via Tim-3

Natural killer (NK) cells, in addition to their cytotoxicity function, harbor prominent cytokine production capabilities and contribute to regulating autoimmune responses. T-cell immunoglobulin and mucin domain containing protein-3 (Tim-3) is one of the inhibitory receptors on NK cells and a promising immune checkpoint target. We recently found that phosphatidylserine (PS) binding to Tim-3 can suppress NK cell activation. Therefore, based on the therapeutic potential of Tim-3 in NK-cell-mediated diseases, we developed a photoswitchable ligand of Tim-3, termed photophosphatidylserine (phoPS), that mimics the effects of PS. Upon 365 or 455 nm light irradiation, the isomer of phoPS cyclically conversed the cis/trans configuration, resulting in an active/inactive Tim-3 ligand, thus modulating the function of NK cells in vitro and in vivo. We also demonstrated that reversible phoPS enabled optical control of acute hepatitis. Together, phoPS may be an appealing tool for autoimmune diseases and cytokine storms in the future.

Associations of Genes for Killer Cell Immunoglobulin-like Receptors and Their Human Leukocyte Antigen-A/B/C Ligands with Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is an immune-mediated disease with a genetic component. The multifactorial pathophysiology is not clear and there is still no pharmacotherapy to slow the growth of aneurysms. The signal integration of cell-surface KIRs (killer cell immunoglobulin-like receptors) with HLA (ligands, human leukocyte class I antigen molecules) modulates the activity of natural killer immune cells. The genetic diversity of the KIR/HLA system is associated with the risk of immune disorders. This study was a multivariate analysis of the association between genetic variants of KIRs, HLA ligands, clinical data and AAA formation. Genotyping was performed by single polymerase chain reaction with sequence-specific primers using commercial assays. Patients with HLA-A-Bw4 have a larger aneurysm by an average of 4 mm (p = 0.008). We observed a relationship between aneurysm diameter and BMI in patients with AAA and co-existing CAD; its shape was determined by the presence of HLA-A-Bw4. There was also a nearly 10% difference in KIR3DL1 allele frequency between the study and control groups. High expression of the cell surface receptor KIR3DL1 may protect, to some extent, against AAA. The presence of HLA-A-Bw4 may affect the rate of aneurysm growth and represents a potential regional pathogenetic risk of autoimmune injury to the aneurysmal aorta.

Reevaluation of NOD/SCID Mice as NK Cell-Deficient Models

Objective

Natural killer (NK) cell-deficient mice are useful models in biomedical research. NOD/SCID mice have been used as a model of this type in research. However, the actual status of NK cells in NOD/SCID mice and CB17/SCID mice in comparison with that in BALB/c mice has not been sufficiently evaluated.

Methods

Splenocytes from naïve or poly(I:C)-treated mice were isolated for phenotyping and analysis of cytotoxicity-related molecules and inhibitory receptors; for cytotoxicity assay, purified NK cells were also used.

Results

The proportion of splenic NK cells did not differ significantly between NOD/SCID and CB17/SCID mice. The perforin levels in NK cells were similar between the poly(I:C)-treated CB17/SCID and NOD/SCID mice, while the granzyme B and NKG2A/C/E levels in NK cells from NOD/SCID mice were significantly lower than those from CB17/SCID mice. Moreover, the NKG2D and Ly49A levels in NK cells from NOD/SCID mice were higher than those from CB17/SCID. The splenocytes from CB17/SCID mice showed higher cytotoxicity than those from NOD/SCID mice, while the cytotoxicity of purified NK cells basically did not differ between the two strains. After in vitro stimulation with cytokines, the splenocytes from CB17/SCID mice showed higher IFN-γ production than those from NOD/SCID mice; however, NK cells did not.

Conclusion

There was no significant difference in the proportion of splenic NK cells between CB17/SCID and NOD/SCID mice, and the function of NK cells was only partially compromised in NOD/SCID mice. Caution should be taken when considering the use of NOD/SCID mice as an NK-deficient model.

The Role of miR-23b in Cancer and Autoimmune Disease

Short-stranded miRNAs are single-stranded RNA molecules involved in the regulation of gene expression. miRNAs are involved in a variety of cellular physiological processes, including cell proliferation, differentiation, and apoptosis. miR-23b have been identified to act both as oncogenes and as tumor suppressors. In addition, miR-23b is related to inflammation resistance to various autoimmune diseases and restrained inflammatory cell migration. The characterization of the specific alterations in the patterns of miR-23b expression in cancer and autoimmune disease has great potential for identifying biomarkers for early disease diagnosis, as well as for potential therapeutic intervention in various diseases. In this review, we summarize the ever-expanding role of miR-23b and its target genes in different models and offer insight into how this multifunctional miRNA modulates tumor cell proliferation and apoptosis or inflammatory cell activation, differentiation, and migration.

Contribution of Antigen-Processing Machinery Genetic Polymorphisms to Atopic Dermatitis

Atopic dermatitis (AD) is a chronic and recurrent inflammatory dermatosis. We recently described an association of the C allele of the single nucleotide polymorphism (SNP) rs26618 in the ERAP1 gene and a synergism of ERAP1 and ERAP2 effects on AD risk. Here, we examined whether polymorphisms of other antigen-presenting machinery genes encoding immunoproteasome components LMP2 and LMP7 and peptide transporter components TAP1 and TAP2 may also affect susceptibility to AD or its outcome. We found that the LMP7 rs2071543*T allele decreased disease risk by about 1.5-fold (odds ratio 0.66, 95% confidence interval 0.44–0.99). On the other hand, the LMP2 rs1351383*C allele reduced the mean age at diagnosis from 23 to 15 years (p < 0.001). Similarly, the TAP1 rs1135216*C allele decreased the mean age at diagnosis from almost 20 to 14 years (p = 0.033). The results are discussed in light of other reports on the role of these polymorphisms in human disease.