Natural killer cells in human autoimmune diseases

Use of a platform with lens-free shadow imaging technology to monitor natural killer cell activity

Natural killer (NK) cells are a crucial component of the innate immune system. This study introduces Cellytics NK, a novel platform for rapid and precise measurement of NK cell activity. This platform combines an NK-specific activation stimulator cocktail (ASC) and lens-free shadow imaging technology (LSIT), using optoelectronic components. LSIT captures digital hologram images of resting and ASC-activated NK cells, while an algorithm evaluates cell size and cytoplasmic complexity using shadow parameters. The combined shadow parameter derived from the peak-to-peak distance and width standard deviation rapidly distinguishes active NK cells from inactive NK cells at the single-cell level within 30 s. Here, the feasibility of the system was demonstrated by assessing NK cells from healthy donors and immunocompromised cancer patients, demonstrating a significant difference in the innate immunity index (I3). Cancer patients showed a lower I3 value (161%) than healthy donors (326%). I3 was strongly correlated with NK cell activity measured using various markers such as interferon-gamma, tumor necrosis factor-alpha, perforin, granzyme B, and CD107a. This technology holds promise for advancing immune functional assays, offering rapid and accurate on-site analysis of NK cells, a crucial innate immune cell, with its compact and cost-effective optoelectronic setup, especially in the post-COVID-19 era.

Dysfunctional natural killer cells can be reprogrammed to regain anti-tumor activity

Natural killer (NK) cells are critical to the innate immune system, as they recognize antigens without prior sensitization, and contribute to the control and clearance of viral infections and cancer. However, a significant proportion of NK cells in mice and humans do not express classical inhibitory receptors during their education process and are rendered naturally "anergic", i.e., exhibiting reduced effector functions. The molecular events leading to NK cell anergy as well as their relation to those underlying NK cell exhaustion that arises from overstimulation in chronic conditions, remain unknown. Here, we characterize the "anergic" phenotype and demonstrate functional, transcriptional, and phenotypic similarities to the "exhausted" state in tumor-infiltrating NK cells. Furthermore, we identify zinc finger transcription factor Egr2 and diacylglycerol kinase DGKα as common negative regulators controlling NK cell dysfunction. Finally, experiments in a 3D organotypic spheroid culture model and an in vivo tumor model suggest that a nanoparticle-based delivery platform can reprogram these dysfunctional natural killer cell populations in their native microenvironment. This approach may become clinically relevant for the development of novel anti-tumor immunotherapeutic strategies.

Genetics and Epigenetics in Acquired Hemophilia A: From Bench to Bedside

Acquired hemophilia A (AHA) is a bleeding disorder characterized by the immunological inhibition of factor VIII (FVIII) of the hemostatic pathway leading to hemorrhagic events. Different domains of FVIII are the target of autoantibodies (mainly immunoglobulin (Ig) G) leading to the deficiency of FVIII. Several factors have been associated with the activation of the auto-immunity towards FVIII. Emerging evidence implicates CD4+ T cell activation in mediating this autoimmune response, with their involvement like that observed in congenital hemophilia A. Several genes such as HLA II DRB*16, DQB1*0502, and CTLA-4 + 49 are responsible for the pathogenesis of AHA. Epigenetic modifications and mainly long-coding RNAS (lncRNAs) are potentially contributing to the pathogenesis of AHA. The treatment approach of AHA includes the management of acute bleeding events and the administration of immunosuppressive medications. This review aimed to summarize the published data on the genetics and epigenetics of AHA. The severity and the mortality of this disease are creating an emerging need for further research in the field of the genetics and epigenetics of acquired hemorrhagic disorder.

Key Genes of the Immune System and Predisposition to Acquired Hemophilia A: Evidence from a Spanish Cohort of 49 Patients Using Next-Generation Sequencing

Acquired hemophilia A (AHA) is a rare bleeding disorder caused by the presence of autoantibodies against factor VIII (FVIII). As with other autoimmune diseases, its etiology is complex and its genetic basis is unknown. The aim of this study was to identify the immunogenetic background that predisposes individuals to AHA. HLA and KIR gene clusters, as well as KLRK1, were sequenced using next-generation sequencing in 49 AHA patients. Associations between candidate genes involved in innate and adaptive immune responses and AHA were addressed by comparing the alleles, genotypes, haplotypes, and gene frequencies in the AHA cohort with those in the donors' samples or Spanish population cohort. Two genes of the HLA cluster, as well as rs1049174 in KLRK1, which tags the natural killer (NK) cytotoxic activity haplotype, were found to be linked to AHA. Specifically, A*03:01 (p = 0.024; odds ratio (OR) = 0.26[0.06-0.85]) and DRB1*13:03 (p = 6.8 × 103, OR = 7.56[1.64-51.40]), as well as rs1049174 (p = 0.012), were significantly associated with AHA. In addition, two AHA patients were found to carry one copy each of the low-frequency allele DQB1*03:09 (nallele = 2, 2.04%), which was completely absent in the donors. To the best of our knowledge, this is the first time that the involvement of these specific alleles in the predisposition to AHA has been proposed. Further molecular and functional studies will be needed to unravel their specific contributions. We believe our findings expand the current knowledge on the genetic factors involved in susceptibility to AHA, which will contribute to improving the diagnosis and prognosis of AHA patients.

Assessment of circulating blood lymphocytes in adult patients on rituximab to treat immune thrombocytopenia: Circulating number of NK cells is associated with the response at 6 months

Immune thrombocytopenia (ITP) is defined by a low platelet count that can trigger potentially life-threatening haemorrhages. Three-quarters of adult patients exhibit persistent or chronic disease and require second-line treatments. Among these, rituximab, an anti-CD20 antibody, has yielded valuable results, with global responses in 60% of patients at 6 months and complete responses in 30% at 5 years. Factors predictive of response to ITP therapy would help physicians choose optimal treatments. We retrospectively analysed clinical courses, biological markers and blood lymphocyte subset numbers of 72 patients on rituximab to treat persistent/chronic ITP followed-up in our department between 2007 and 2021, divided into three groups according to the platelet count at 6 months: complete, partial or no response. Among all studied parameters, a low number of CD3^- CD16⁺ CD56⁺ circulating NK cells was associated with the complete response to rituximab. We also found that, after rituximab therapy, complete responders exhibited increased NK and decreased activated CD8⁺ T cell percentages. These results emphasize that the role played by NK cells in ITP remains incompletely known but that factors predictive of response to rituximab can be easily derived using blood lymphocyte subset data.

Longitudinal global transcriptomic profiling of preclinical systemic sclerosis reveals molecular changes associated with disease progression

OBJECTIVE

To investigate peripheral blood cell (PBCs) global gene expression profile of SSc at its preclinical stage (PreSSc) and to characterize the molecular changes associated with progression to a definite disease over time.

MATERIAL AND METHODS

Clinical data and PBCs of 33 participants with PreSSc and 16 healthy controls (HCs) were collected at baseline and follow-up (mean 4.2 years). Global gene expression profiling was conducted by RNA sequencing and a modular analysis was performed.

RESULTS

Comparison of baseline PreSSc to HCs revealed 2889 differentially expressed genes. Interferon signalling was the only activated pathway among top over-represented pathways. Moreover, 10 modules were significantly decreased in PreSSc samples (related to lymphoid lineage, cytotoxic/NK cell, and erythropoiesis) in comparison to HCs. At follow-up, 14 subjects (42.4%) presented signs of progression (evolving PreSSc) and 19 remained in stable preclinical stage (stable PreSSc). Progression was not associated with baseline clinical features or baseline PBC transcript modules. At follow-up stable PreSSc normalized their down-regulated cytotoxic/NK cell and protein synthesis modules while evolving PreSSc kept a down-regulation of cytotoxic/NK cell and protein synthesis modules. Transcript level changes of follow-up vs baseline in stable PreSSc vs evolving PreSSc showed 549 differentially expressed transcripts (336 up and 213 down) with upregulation of the EIF2 Signalling pathway.

CONCLUSIONS

Participants with PreSSc had a distinct gene expression profile indicating that molecular differences at a transcriptomic level are already present in the preclinical stages of SSc. Furthermore, a reduced NK signature in PBCs was related to SSc progression over time.

The co-inhibitory receptor TIGIT regulates NK cell function and is upregulated in human intrahepatic CD56bright NK cells

The crosstalk between NK cells and their surrounding environment is enabled through activating and inhibitory receptors, which tightly control NK cell activity. The co-inhibitory receptor TIGIT decreases NK cell cytotoxicity and is involved in NK cell exhaustion, but has also been associated with liver regeneration, highlighting that the contribution of human intrahepatic CD56bright NK cells in regulating tissue homeostasis remains incompletely understood. A targeted single-cell mRNA analysis revealed distinct transcriptional differences between matched human peripheral blood and intrahepatic CD56bright NK cells. Multiparameter flow cytometry identified a cluster of intrahepatic NK cells with overlapping high expression of CD56, CD69, CXCR6, TIGIT and CD96. Intrahepatic CD56bright NK cells also expressed significantly higher protein surface levels of TIGIT, and significantly lower levels of DNAM-1 compared to matched peripheral blood CD56bright NK cells. TIGIT+ CD56bright NK cells showed diminished degranulation and TNF-α production following stimulation. Co-incubation of peripheral blood CD56bright NK cells with human hepatoma cells or primary human hepatocyte organoids resulted in migration of NK cells into hepatocyte organoids and upregulation of TIGIT and downregulation of DNAM-1 expression, in line with the phenotype of intrahepatic CD56bright NK cells. Intrahepatic CD56bright NK cells represent a transcriptionally, phenotypically, and functionally distinct population of NK cells that expresses higher levels of TIGIT and lower levels of DNAM-1 than matched peripheral blood CD56bright NK cells. Increased expression of inhibitory receptors by NK cells within the liver environment can contribute to tissue homeostasis and reduction of liver inflammation.

Antiphospholipid antibody-mediated NK cell cytotoxicity

Antiphospholipid syndrome (APS) is an autoimmune thrombophilia that is characterised by thrombosis and obstetric complications in the presence of antiphospholipid antibodies (aPL). Pregnancy complications remain a challenging problem for patients with APS, especially during the first trimester. Although natural killer (NK) cells constitute up to 70% of decidual lymphocytes during the first trimester, their contribution to early pregnancy loss in APS is largely unknown. We aimed to analyse whether aPL are able to recruit antibody-dependent cellular cytotoxicity (ADCC) of NK cells, with special emphasis on the differences in the effects of aPL containing anti-β2GPI domain 1 (anti-β2GPI-D1) antibodies (aPL+/D1+) and those that do not (aPL+/D1-). Our findings revealed a differential distribution of NK subsets in the presence of different aPL. Namely, aPL+/D1- IgGs increased CD56^dim/CD16^dim cells, while aPL+/D1 + IgGs increased the number of CD56^bright/CD16^dim cells. ADCC NK cell cytotoxicity was found to be higher in the presence of aPL+/D1- IgGs, as defined by an increased target cell death, degranulation and increased expression of CD11b, CD69 and NKG2D. Overall, our evidence showed that aPL are able to recruit ADCC, suggesting NK cells as candidate cells for APS-related obstetric complications.

Deciphering the role of autophagy in the immunopathogenesis of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a typical immune-mediated chronic inflammatory disorder. Following the industrialization and changes in lifestyle, the incidence of IBD in the world is rising, which makes health concerns and heavy burdens all over the world. However, the pathogenesis of IBD remains unclear, and the current understanding of the pathogenesis involves dysregulation of mucosal immunity, gut microbiome dysbiosis, and gut barrier defect based on genetic susceptibility and environmental triggers. In recent years, autophagy has emerged as a key mechanism in IBD development and progression because Genome-Wide Association Study revealed the complex interactions of autophagy in IBD, especially immunopathogenesis. Besides, autophagy markers are also suggested to be potential biomarkers and target treatment in IBD. This review summarizes the autophagy-related genes regulating immune response in IBD. Furthermore, we explore the evolving evidence that autophagy interacts with intestinal epithelial and immune cells to contribute to the inflammatory changes in IBD. Finally, we discuss how novel discovery could further advance our understanding of the role of autophagy and inform novel therapeutic strategies in IBD.

Dysregulation of immunity in COVID-19 and SLE

The immune response plays a crucial role in preventing diseases, such as infections. There are two types of immune responses, specific and innate immunity, each of which consists of two components: cellular immunity and humoral immunity. Dysfunction in any immune system component increases the risk of developing certain diseases. Systemic lupus erythematosus (SLE), an autoimmune disease in the human body, develops an immune response against its own components. In these patients, due to underlying immune system disorders and receipt of immunosuppressive drugs, the susceptibility to infections is higher than in the general population and is the single largest cause of mortality in this group. COVID-19 infection, which first appeared in late 2019, has caused several concerns in patients with SLE. However, there is no strong proof of additional risk of developing COVID-19 in patients with SLE, and in some cases, studies have shown less severity of the disease in these individuals. This review paper discusses the immune disorders in SLE and COVID-19.

Upregulation of Cytotoxic T-cells in pediatric patients with Gaucher disease

Cytotoxic (CD8) T-cells and natural killer (NK) cells have a significant immune function role. The ongoing stimulation of immunity and the excessive release of proinflammatory cytokines observed in pediatric patients with Gaucher disease (GD) can affect immune cells. Few studies have looked at the proportion of cytotoxic CD8 T-cells and their subsets in children with GD. A prospective case-control study was performed involving twenty pediatric patients with type 1 GD and twenty healthy age-matched controls. All patients received regular enzyme replacement therapy (ERT) for at least 6 months before the study. Complete blood count and flow cytometric analyses of CD8 T, Tc1, Tc2, NK, and NK T-cells were performed. GD patients showed significantly increased of CD8 T, Tc1 and significantly decreased NK cells frequencies when compared to healthy controls. However, no significant difference in Tc2 and NK T-cells was found between the studied groups. GD patients on regular ERT have increased CD8+ T-cell frequencies, predominantly Tc1, together with a reduction in NK cells than in healthy controls. These crucial immunological changes may contribute to some extent to the pathogenesis and the progression of GD.

Capturing SNP Association across the NK Receptor and HLA Gene Regions in Multiple Sclerosis by Targeted Penalised Regression Models

Conventional genome-wide association studies (GWASs) of complex traits, such as Multiple Sclerosis (MS), are reliant on per-SNP p-values and are therefore heavily burdened by multiple testing correction. Thus, in order to detect more subtle alterations, ever increasing sample sizes are required, while ignoring potentially valuable information that is readily available in existing datasets. To overcome this, we used penalised regression incorporating elastic net with a stability selection method by iterative subsampling to detect the potential interaction of loci with MS risk. Through re-analysis of the ANZgene dataset (1617 cases and 1988 controls) and an IMSGC dataset as a replication cohort (1313 cases and 1458 controls), we identified new association signals for MS predisposition, including SNPs above and below conventional significance thresholds while targeting two natural killer receptor loci and the well-established HLA loci. For example, rs2844482 (98.1% iterations), otherwise ignored by conventional statistics (p = 0.673) in the same dataset, was independently strongly associated with MS in another GWAS that required more than 40 times the number of cases (~45 K). Further comparison of our hits to those present in a large-scale meta-analysis, confirmed that the majority of SNPs identified by the elastic net model reached conventional statistical GWAS thresholds (p < 5 × 10−8) in this much larger dataset. Moreover, we found that gene variants involved in oxidative stress, in addition to innate immunity, were associated with MS. Overall, this study highlights the benefit of using more advanced statistical methods to (re-)analyse subtle genetic variation among loci that have a biological basis for their contribution to disease risk.

NK Cell Patterns in Idiopathic Inflammatory Myopathies with Pulmonary Affection

BACKGROUND

Pulmonary affection (PA) is associated with a substantial increase in morbidity and mortality in patients with idiopathic inflammatory myopathies (IIM). However, the underlying immune mechanisms of PA remain enigmatic and prompt deeper immunological analyses. Importantly, the Janus-faced role of natural killer (NK) cells, capable of pro-inflammatory as well as regulatory effects, might be of interest for the pathophysiologic understanding of PA in IIM.

METHODS

To extend our understanding of immunological alterations in IIM patients with PA, we compared the signatures of NK cells in peripheral blood using multi-color flow cytometry in IIM patients with (n = 12, of which anti-synthetase syndrome = 8 and dermatomyositis = 4) or without PA (n = 12).

RESULTS

We did not observe any significant differences for B cells, CD4, and CD8 T cells, while total NK cell numbers in IIM patients with PA were reduced compared to non-PA patients. NK cell alterations were driven by a particular decrease of CD56^dim NK cells, while CD56^bright NK cells remained unchanged. Comparisons of the cell surface expression of a large panel of NK receptors revealed an increased mean fluorescence intensity of NKG2D⁺ on NK cells from patients with PA compared with non-PA patients, especially on the CD56^dim subset. NKG2D⁺ and NKp46⁺ cell surface levels were associated with reduced vital capacity, serving as a surrogate marker for clinical severity of PA.

CONCLUSION

Our data illustrate that PA in IIM is associated with alterations of the NK cell repertoire, suggesting a relevant contribution of NK cells in certain IIMs, which might pave the way for NK cell-targeted therapeutic approaches.

Inflammation and Mitochondrial Dysfunction in Autism Spectrum Disorder

Autism Spectrum Disorders (ASD) is a severe childhood psychiatric condition with an array of cognitive, language and social impairments that can significantly impact family life. ASD is classically characterized by reduced communication skills and social interactions, with limitations imposed by repetitive patterns of behavior, interests, and activities. The pathophysiology of ASD is thought to arise from complex interactions between environmental and genetic factors within the context of individual development. A growing body of research has raised the possibility of identifying the aetiological causes of the disorder. This review highlights the roles of immune-inflammatory pathways, nitro-oxidative stress and mitochondrial dysfunctions in ASD pathogenesis and symptom severity. The role of NK-cells, T helper, T regulatory and B-cells, coupled with increased inflammatory cytokines, lowered levels of immune-regulatory cytokines, and increased autoantibodies and microglial activation is elucidated. It is proposed that alterations in mitochondrial activity and nitrooxidative stress are intimately associated with activated immune-inflammatory pathways. Future research should determine as to whether the mitochondria, immune-inflammatory activity and nitrooxidative stress changes in ASD affect the development of amygdala-frontal cortex interactions. A number of treatment implications may arise, including prevention-orientated prenatal interventions, treatment of pregnant women with vitamin D, and sodium butyrate. Treatments of ASD children and adults with probiotics, sodium butyrate and butyrate-inducing diets, antipurinergic therapy with suramin, melatonin, oxytocin and taurine are also discussed.

Partitioned glioma heritability shows subtype-specific enrichment in immune cells

BACKGROUND

Epidemiological studies of adult glioma have identified genetic syndromes and 25 heritable risk loci that modify individual risk for glioma, as well increased risk in association with exposure to ionizing radiation and decreased risk in association with allergies. In this analysis, we assess whether there is a shared genome-wide genetic architecture between glioma and atopic/autoimmune diseases.

METHODS

Using summary statistics from a glioma genome-wide association studies (GWAS) meta-analysis, we identified significant enrichment for risk variants associated with gene expression changes in immune cell populations. We also estimated genetic correlations between glioma and autoimmune, atopic, and hematologic traits using linkage disequilibrium score regression (LDSC), which leverages genome-wide single-nucleotide polymorphism (SNP) associations and patterns of linkage disequilibrium.

RESULTS

Nominally significant negative correlations were observed for glioblastoma (GB) and primary biliary cirrhosis (rg = -0.26, P = .0228), and for non-GB gliomas and celiac disease (rg = -0.32, P = .0109). Our analyses implicate dendritic cells (GB pHM = 0.0306 and non-GB pHM = 0.0186) in mediating both GB and non-GB genetic predisposition, with GB-specific associations identified in natural killer (NK) cells (pHM = 0.0201) and stem cells (pHM = 0.0265).

CONCLUSIONS

This analysis identifies putative new associations between glioma and autoimmune conditions with genomic architecture that is inversely correlated with that of glioma and that T cells, NK cells, and myeloid cells are involved in mediating glioma predisposition. This provides further evidence that increased activation of the acquired immune system may modify individual susceptibility to glioma.

A new molecular classification to drive precision treatment strategies in primary Sjögren's syndrome

There is currently no approved treatment for primary Sjögren's syndrome, a disease that primarily affects adult women. The difficulty in developing effective therapies is -in part- because of the heterogeneity in the clinical manifestation and pathophysiology of the disease. Finding common molecular signatures among patient subgroups could improve our understanding of disease etiology, and facilitate the development of targeted therapeutics. Here, we report, in a cross-sectional cohort, a molecular classification scheme for Sjögren's syndrome patients based on the multi-omic profiling of whole blood samples from a European cohort of over 300 patients, and a similar number of age and gender-matched healthy volunteers. Using transcriptomic, genomic, epigenetic, cytokine expression and flow cytometry data, combined with clinical parameters, we identify four groups of patients with distinct patterns of immune dysregulation. The biomarkers we identify can be used by machine learning classifiers to sort future patients into subgroups, allowing the re-evaluation of response to treatments in clinical trials.

Complete deconvolution of DNA methylation signals from complex tissues: a geometric approach

MOTIVATION

It is a common practice in epigenetics research to profile DNA methylation on tissue samples, which is usually a mixture of different cell types. To properly account for the mixture, estimating cell compositions has been recognized as an important first step. Many methods were developed for quantifying cell compositions from DNA methylation data, but they mostly have limited applications due to lack of reference or prior information.

RESULTS

We develop Tsisal, a novel complete deconvolution method which accurately estimate cell compositions from DNA methylation data without any prior knowledge of cell types or their proportions. Tsisal is a full pipeline to estimate number of cell types, cell compositions and identify cell-type-specific CpG sites. It can also assign cell type labels when (full or part of) reference panel is available. Extensive simulation studies and analyses of seven real datasets demonstrate the favorable performance of our proposed method compared with existing deconvolution methods serving similar purpose.

AVAILABILITY AND IMPLEMENTATION

The proposed method Tsisal is implemented as part of the R/Bioconductor package TOAST at https://bioconductor.org/packages/TOAST.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Siplizumab Induces NK Cell Fratricide Through Antibody-Dependent Cell-Mediated Cytotoxicity

The glycoprotein CD2 is expressed on T and NK cells and contributes to cell-cell conjugation, agonistic signaling and actin cytoskeleton rearrangement. CD2 has previously been shown to have an important function in natural NK cell cytotoxicity but to be expendable in antibody-mediated cytotoxicity. Siplizumab is a monoclonal anti-CD2 IgG1 antibody that is currently undergoing clinical trials in the field of transplantation. This study investigated the effect of CD2 binding and Fc γ receptor binding by siplizumab (Fc-active) and Fc-silent anti-CD2 monoclonal antibodies in allogeneic mixed lymphocyte reaction and autologous lymphocyte culture. Further, induction of NK cell fratricide and inhibition of natural cytotoxicity as well as antibody-dependent cytotoxicity by these agents were assessed. Blockade of CD2 via monoclonal antibodies in the absence of Fc γ receptor binding inhibited NK cell activation in allogeneic mixed lymphocyte reaction. In contrast, siplizumab increased NK cell activation in both mixed lymphocyte reaction and autologous lymphocyte culture due to FcγRIIIA binding. However, experiments using purified NK cells did not show an inhibitory effect of CD2 blockade on natural cytotoxicity or antibody-dependent cytotoxicity. Lastly, it was shown that siplizumab induces NK cell fratricide. Concluding, siplizumab is a promising biopharmaceutical drug candidate for depletion of T and NK cells with minimal off-target effects.

COVID-19, rheumatic diseases and immune dysregulation-a perspective

The COVID-19 pandemic has resulted in widespread hospitalisations and deaths around the world. As patients with rheumatic diseases generally have increased risk of infections and complications, understandably, there is significant concern of the impact of SARS-CoV-2 on these patients. However, there is a paucity of data in rheumatic patients. We review mechanisms through which SARS-CoV-2 results in infection, including ACE2 receptor, and complications (including immune dysregulation, thrombosis and complement activation). We assess these pathways in patients with rheumatic disease and those on immune modulating therapy. Although data thus far does not appear to show worse outcomes in rheumatic patients as a whole, given alterations in the underlying immune pathways in certain diseases (such as systemic lupus erythematosus), we posit that the risk is not equal in all rheumatic patients. We also discuss the benefit of underlying disease control with respect to COVID-19 risk reduction and potential increased risk of disease flares following viral infection from an immune standpoint.

Tim-3 associated with apoptotic NK cells and disease activity in SLE

T cell immunoglobulin and mucin domain-containing molecule-3 (Tim-3) has been found to play important roles in systemic lupus erythematosus (SLE), however, whether Tim-3 is involved in apoptosis of NK cells in SLE remains unknown. The proportion of CD3−CD56+ NK cells and the percentage of AnnexinV+ NK cells were analyzed by flow cytometry in SLE patients and healthy controls. Tim-3 expression on NK cells was also evaluated by flow cytometry. We firstly observed a decreased proportion of NK cells and an increased proportion of apoptotic NK cells in SLE patients. The proportion of apoptotic NK cells was positively correlated with anti-dsDNA and SLEDAI. Tim-3 expression on NK cells was up-regulated in SLE patients. Further analysis showed that Tim-3 expression on NK cells was negatively correlated with the proportion of apoptotic NK cells, anti-dsDNA and SLEDAI, while positively correlated with the proportion of NK cells. The present results suggest that Tim-3 might play roles in SLE by regulating the apoptosis of NK cells and Tim-3 might serve as a potential target for the treatment of SLE.

Interleukin 4 deficiency limits the development of a lupus-like disease in mice triggered by phospholipids in a non-bilayer arrangement

Non-bilayer phospholipids arrangements (NPAs) are transient molecular associations different from lipid bilayers. When they become stable, they can trigger a disease in mice resembling human lupus, which is mainly characterized by the production of anti-NPA IgG antibodies. NPAs are stabilized on liposomes or cell bilayers by the drugs procainamide or chlorpromazine, which produce drug-induced lupus in humans. Here, we evaluated the participation of the T_H 2 response, through its hallmark cytokine IL-4, on the development of the lupus-like disease in mice. Wild-type or IL-4 knockout BALB/c mice received liposomes bearing drug-induced NPAs, the drugs alone, or an anti-NPA monoclonal antibody (H308) to induce the lupus-like disease (the last two procedures stabilize NPAs on mice cells). IL-4 KO mice showed minor disease manifestations, compared to wild-type mice, with decreased production of anti-NPA IgG antibodies, no anti-cardiolipin, anti-histones and anticoagulant antibodies, and no kidney or skin lesions. In these mice, H308 was the only inducer of anti-NPA IgG antibodies. These findings indicate that IL-4 has a central role in the development of the murine lupus-like disease induced by NPA stabilization.

NK cell-derived GM-CSF potentiates inflammatory arthritis and is negatively regulated by CIS

Despite increasing recognition of the importance of GM-CSF in autoimmune disease, it remains unclear how GM-CSF is regulated at sites of tissue inflammation. Using GM-CSF fate reporter mice, we show that synovial NK cells produce GM-CSF in autoantibody-mediated inflammatory arthritis. Synovial NK cells promote a neutrophilic inflammatory cell infiltrate, and persistent arthritis, via GM-CSF production, as deletion of NK cells, or specific ablation of GM-CSF production in NK cells, abrogated disease. Synovial NK cell production of GM-CSF is IL-18–dependent. Furthermore, we show that cytokine-inducible SH2-containing protein (CIS) is crucial in limiting GM-CSF signaling not only during inflammatory arthritis but also in experimental allergic encephalomyelitis (EAE), a murine model of multiple sclerosis. Thus, a cellular cascade of synovial macrophages, NK cells, and neutrophils mediates persistent joint inflammation via production of IL-18 and GM-CSF. Endogenous CIS provides a key brake on signaling through the GM-CSF receptor. These findings shed new light on GM-CSF biology in sterile tissue inflammation and identify several potential therapeutic targets.

Innate lymphocytes: pathogenesis and therapeutic targets of liver diseases and cancer

The liver is a lymphoid organ with unique immunological properties, particularly, its predominant innate immune system. The balance between immune tolerance and immune activity is critical to liver physiological functions and is responsible for the sensitivity of this organ to numerous diseases, including hepatotropic virus infection, alcoholic liver disease, nonalcoholic fatty liver disease, autoimmune liver disease, and liver cancer, which are major health problems globally. In the past decade, with the discovery of liver-resident natural killer cells, the importance of innate lymphocytes with tissue residency has gradually become the focus of research. In this review, we address the current knowledge regarding hepatic innate lymphocytes with unique characteristics, including NK cells, ILC1/2/3s, NKT cells, γδ T cells, and MAIT cells, and their potential roles in liver homeostasis maintenance and the progression of liver diseases and cancer. A better understanding of the immunopathogenesis of hepatic innate lymphocytes will be helpful for proposing effective treatments for liver diseases and cancer.

The innate immune perspective of autoimmune and autoinflammatory conditions

Innate immunity is one of two immune defence system arms. It is present at birth and does not require ‘learning’ through exposure to foreign organisms. It activates various mechanisms collectively to eliminate pathogens and hold an infection until the adaptive response are mounted. The innate immune system consists of four elements: the epithelial barrier, cells (e.g. macrophages, NK cells), plasma proteins (e.g. complement) and cytokines. These components act in concert to induce complex processes, as well as recruitment, activation and differentiation of adaptive responses. The innate response is more than just the ‘first line of defence’, as it essentially withholds the vast majority of any intruder, has a complex interplay with the adaptive arm and is crucial for survival of the host. Finally, yet importantly, a myriad of diseases has been linked with innate immune dysregulation. In this mini-review we will shed some light on these conditions, particularly regarding autoinflammatory ones.

Phenotype of Innate Immune Cells in Uveitis Associated with Axial Spondyloarthritis- and Juvenile Idiopathic Arthritis-associated Uveitis

Purpose: To analyze circulating immune cells in patients with anterior uveitis (AU) associated to axial spondyloarthritis (SpA), or juvenile idiopathic arthritis (JIA).Methods: Venous blood samples were collected from healthy controls (n = 16), and either SpA (n = 19) or JIA (n = 23) patients with associated anterior uveitis (AU) during active flare, or after ≥3 months of inactivity. Frequencies of CD56⁺, MHC-I⁺, and S100A9⁺ monocytes, CCR7⁺ dendritic cells, CD56^+dim natural killer (NK) cells and CD3⁺CD56^bright T-cells were analyzed via flow cytometry. Serum S100A8/A9 levels were determined via ELISA.Results: SpA patients showed a reduced frequency of CD56^+dim NK cells during uveitis activity, a constitutively activated monocyte phenotype, and elevated S100A8/A9 serum levels. In contrast, JIAU patients showed elevated frequencies of CD56⁺ monocytes and CCR7⁺ DC.Conclusion: Phenotype of peripheral immune cells differ between patients, probably contributing to different courses of acute onset AU in SpA and insidious onset AU in JIAU patients.Abbreviations: AU: anterior uveitis, AR: arthritis, JIA: juvenile idiopathic arthritis, SpA: axial spondyloarthritis.

Targeting immunometabolism as an anti-inflammatory strategy

The growing field of immunometabolism has taught us how metabolic cellular reactions and processes not only provide a means to generate ATP and biosynthetic precursors, but are also a way of controlling immunity and inflammation. Metabolic reprogramming of immune cells is essential for both inflammatory as well as anti-inflammatory responses. Four anti-inflammatory therapies, DMF, Metformin, Methotrexate and Rapamycin all work by affecting metabolism and/or regulating or mimicking endogenous metabolites with anti-inflammatory effects. Evidence is emerging for the targeting of specific metabolic events as a strategy to limit inflammation in different contexts. Here we discuss these recent developments and speculate on the prospect of targeting immunometabolism in the effort to develop novel anti-inflammatory therapeutics. As accumulating evidence for roles of an intricate and elaborate network of metabolic processes, including lipid, amino acid and nucleotide metabolism provides key focal points for developing new therapies, we here turn our attention to glycolysis and the TCA cycle to provide examples of how metabolic intermediates and enzymes can provide potential novel therapeutic targets.

Cytotoxic Immunity in Peripheral Nerve Injury and Pain

Cytotoxicity and consequent cell death pathways are a critical component of the immune response to infection, disease or injury. While numerous examples of inflammation causing neuronal sensitization and pain have been described, there is a growing appreciation of the role of cytotoxic immunity in response to painful nerve injury. In this review we highlight the functions of cytotoxic immune effector cells, focusing in particular on natural killer (NK) cells, and describe the consequent action of these cells in the injured nerve as well as other chronic pain conditions and peripheral neuropathies. We describe how targeted delivery of cytotoxic factors via the immune synapse operates alongside Wallerian degeneration to allow local axon degeneration in the absence of cell death and is well-placed to support the restoration of homeostasis within the nerve. We also summarize the evidence for the expression of endogenous ligands and receptors on injured nerve targets and infiltrating immune cells that facilitate direct neuro-immune interactions, as well as modulation of the surrounding immune milieu. A number of chronic pain and peripheral neuropathies appear comorbid with a loss of function of cellular cytotoxicity suggesting such mechanisms may actually help to resolve neuropathic pain. Thus while the immune response to peripheral nerve injury is a major driver of maladaptive pain, it is simultaneously capable of directing resolution of injury in part through the pathways of cellular cytotoxicity. Our growing knowledge in tuning immune function away from inflammation toward recovery from nerve injury therefore holds promise for interventions aimed at preventing the transition from acute to chronic pain.

Characterizing the Dysfunctional NK Cell: Assessing the Clinical Relevance of Exhaustion, Anergy, and Senescence

There is a growing body of literature demonstrating the importance of T cell exhaustion in regulating and shaping immune responses to pathogens and cancer. Simultaneously, the parallel development of therapeutic antibodies targeting inhibitory molecules associated with immune exhaustion (such as PD-1, but also TIGIT, and LAG-3) has led to a revolution in oncology with dramatic benefits in a growing list of solid and hematologic malignancies. Given this success in reinvigorating exhausted T cells and the related anti-tumor effects, there are increasing efforts to apply immune checkpoint blockade to other exhausted immune cells beyond T cells. One approach involves the reinvigoration of “exhausted” NK cells, a non-T, non-B lymphoid cell of the innate immune system. However, in contrast to the more well-defined and established molecular, genetic, and immunophenotypic characteristics of T cell exhaustion, a consensus on the defining functional and phenotypic features of NK “exhaustion” is less clear. As is well-known from T cell biology, separate and distinct molecular and cellular processes including senescence, anergy and exhaustion can lead to diminished immune effector function with different implications for immune regulation and recovery. For NK cells, it is unclear if exhaustion, anergy, and senescence entail separate and distinct entities of dysfunction, though all are typically characterized by decreased effector function or proliferation. In this review, we seek to define these distinct spheres of NK cell dysfunction, analyzing how they have been shown to impact NK biology and clinical applications, and ultimately highlight key characteristics in NK cell function, particularly in relation to the role of “exhaustion.”

Dysregulation of TLR9 in neonates leads to fatal inflammatory disease driven by IFN-γ

Recognition of self-nucleic acids by innate immune receptors can lead to the development of autoimmune and/or autoinflammatory diseases. Elucidating mechanisms associated with dysregulated activation of specific receptors may identify new disease correlates and enable more effective therapies. Here we describe an aggressive in vivo model of Toll-like receptor (TLR) 9 dysregulation, based on bypassing the compartmentalized activation of TLR9 in endosomes, and use it to uncover unique aspects of TLR9-driven disease. By inducing TLR9 dysregulation at different stages of life, we show that while dysregulation in adult mice causes a mild systemic autoinflammatory disease, dysregulation of TLR9 early in life drives a severe inflammatory disease resulting in neonatal fatality. The neonatal disease includes some hallmarks of macrophage activation syndrome but is much more severe than previously described models. Unlike TLR7-mediated disease, which requires type I interferon (IFN) receptor signaling, TLR9-driven fatality is dependent on IFN-γ receptor signaling. NK cells are likely key sources of IFN-γ in this model. We identify populations of macrophages and Ly6C^hi monocytes in neonates that express high levels of TLR9 and low levels of TLR7, which may explain why TLR9 dysregulation is particularly consequential early in life, while symptoms of TLR7 dysregulation take longer to manifest. Overall, this study demonstrates that inappropriate TLR9 responses can drive a severe autoinflammatory disease under homeostatic conditions and highlights differences in the diseases resulting from inappropriate activation of TLR9 and TLR7.

Immunological Drivers in Graves' Disease: NK Cells as a Master Switcher

Graves' disease (GD) is a common autoimmune cause of hyperthyroidism, which is eventually related to the generation of IgG antibodies stimulating the thyrotropin receptor. Clinical manifestations of the disease reflect hyperstimulation of the gland, causing thyrocyte hyperplasia (goiter) and excessive thyroid hormone synthesis (hyperthyroidism). The above clinical manifestations are preceded by still partially unraveled pathogenic actions governed by the induction of aberrant phenotype/functions of immune cells. In this review article we investigated the potential contribution of natural killer (NK) cells, based on literature analysis, to discuss the bidirectional interplay with thyroid hormones (TH) in GD progression. We analyzed cellular and molecular NK-cell associated mechanisms potentially impacting on GD, in a view of identification of the main NK-cell subset with highest immunoregulatory role.

Immune cell infiltration characteristics and related core genes in lupus nephritis: results from bioinformatic analysis

BACKGROUND

Lupus nephritis (LN) is a common complication of systemic lupus erythematosus that presents a high risk of end-stage renal disease. In the present study, we used CIBERSORT and gene set enrichment analysis (GSEA) of gene expression profiles to identify immune cell infiltration characteristics and related core genes in LN.

RESULTS

Datasets from the Gene Expression Omnibus, GSE32591 and GSE113342, were downloaded for further analysis. The GSE32591 dataset, which included 32 LN glomerular biopsy tissues and 14 glomerular tissues from living donors, was analyzed by CIBERSORT. Different immune cell types in LN were analyzed by the Limma software. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis based on GSEA were performed by clusterProfiler software. Lists of core genes were derived from Spearman correlation between the most significant GO term and differentially expressed immune cell gene from CIBERSORT. GSE113342 was employed to validate the association between selected core genes and clinical manifestation. Five types of immune cells revealed important associations with LN, and monocytes emerged as having the most prominent differences. GO and KEGG analyses indicated that immune response pathways are significantly enriched in LN. The Spearman correlation indicated that 15 genes, including FCER1G, CLEC7A, MARCO, CLEC7A, PSMB9, and PSMB8, were closely related to clinical features.

CONCLUSIONS

This study is the first to identify immune cell infiltration with microarray data of glomeruli in LN by using CIBERSORT analysis and provides novel evidence and clues for further research of the molecular mechanisms of LN.

Disturbances in NK Cells in Various Types of Hemophagocytic Lymphohistiocytosis in a Population of Polish Children

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disease associated with immune system hyperactivation and the appearance of serious systemic disturbances. The purpose of this study was an assessment of natural killer (NK) cell disturbances in a group of children with clinical signs of HLH. A total of 43 children with HLH and 17 healthy children were enrolled in the study. NK phenotyping, intracellular perforin staining, and cytotoxicity tests were performed by using the flow cytometry method. HLH patients were divided into 6 HLH types: 9% infection-related HLH; 7% malignancy-related HLH; 21% macrophage activating syndrome; 12% familial hemophagocytic lymphohistiocytosis; 2% X-linked lymphoproliferative syndrome; and 49% as HLH of unknown background. A positive correlation was observed between cytotoxicity and NK cells in children with HLH (P=0.01). In all HLH groups, the percentage of NK cells was significantly lower than in the control population. The spontaneous cytotoxicity was significantly lower in HLH patients. The results presented in this study indicate the importance of impaired function and the number of NK cells in the pathogenesis of HLH. Nonetheless, the background of disturbances seems to be different in various cases.

Decreased A20 expression on circulating CD56bright NK cells contributes to a worse disease status in patients with ankylosing spondylitis

A20, a pivotal anti-inflammatory protein, preserves immune homeostasis and regulates prolonged inflammation. A previous study has shown that A20 expression levels are down-regulated in peripheral blood mononuclear cells (PBMCs) from patients with ankylosing spondylitis (AS). However, the precise role of A20 in reducing autoimmune disorders needs to be further elucidated. In this study, A20 expression was found to be preferentially reduced on circulating CD56^bright natural killer (NK) cells in patients with AS, and its level was negatively correlated with that of proinflammatory cytokines. Further investigation demonstrated that A20 reduces interferon (IFN)-γ and tumour necrosis factor (TNF)-α production in CD56^bright NK cells after stimulation with monokines or phorbol myristate acetate (PMA)/ionomycin(P/I). Furthermore, CD56^bright NK cells isolated from AS patients promote TNF-α secretion by autologous monocytes, and increasing the A20 expression level partially attenuates this process. More importantly, decreased A20 expression on circulating CD56^bright NK cells is associated with worse disease status in patients with AS. Our findings reveal that A20 participates in the pathogenesis of AS by negatively regulating CD56^bright NK cells and that its reduced expression contributes to a worsened disease status in patients with AS.

The role of interleukin-1 in general pathology

Interleukin-1, an inflammatory cytokine, is considered to have diverse physiological functions and pathological significances and play an important role in health and disease. In this decade, interleukin-1 family members have been expanding and evidence is accumulating that highlights the importance of interleukin-1 in linking innate immunity with a broad spectrum of diseases beyond inflammatory diseases. In this review, we look back on the definition of "inflammation" in traditional general pathology and discuss new insights into interleukin-1 in view of its history and the molecular bases of diseases, as well as current progress in therapeutics.

Pretransplant transcriptomic signature in peripheral blood predicts early acute rejection

Commonly available clinical parameters fail to predict early acute cellular rejection (EAR, occurring within 6 months after transplant), a major risk factor for graft loss after kidney transplantation. We performed whole-blood RNA sequencing at the time of transplant in 235 kidney transplant recipients enrolled in a prospective cohort study (Genomics of Chronic Allograft Rejection [GoCAR]) and evaluated the relationship of pretransplant transcriptomic profiles with EAR. EAR was associated with downregulation of NK and CD8+ T cell gene signatures in pretransplant blood. We identified a 23-gene set that predicted EAR in the discovery (n = 81, and AUC = 0.80) and validation (n = 74, and AUC = 0.74) sets. Exclusion of recipients with 5 or 6 HLA donor mismatches increased the AUC to 0.89. The risk score derived from the gene set was also significantly associated with acute cellular rejection after 6 months, antibody-mediated rejection and/or de novo donor-specific antibodies, and graft loss in a cohort of 154 patients, combining the validation set and additional GoCAR patients with surveillance biopsies between 6 and 24 months (n = 80) posttransplant. This 23-gene set is a potentially important new tool for determination of the recipient's immunological risk before kidney transplantation, and facilitation of an individualized approach to immunosuppressive therapy.

Natural Killer Cells and Thyroid Diseases

Abnormal production of thyroid hormone is one of the common endocrine disorders, and thyroid hormone production declines with age. The aging process also negatively affects the immune system. An interaction between endocrine system and the immune system has been proposed to be bidirectional. Emerging evidence suggests an interaction between a lymphocyte population, called natural killer (NK) cells and thyroid gland function. Here, we review the relationship between NK cells and thyroid function and disease.

Engineering the TGFβ Receptor to Enhance the Therapeutic Potential of Natural Killer Cells as an Immunotherapy for Neuroblastoma

PURPOSE

The ability of natural killer (NK) cells to lyse allogeneic targets, without the need for explicit matching or priming, makes them an attractive platform for cell-based immunotherapy. Umbilical cord blood is a practical source for generating banks of such third-party NK cells for "off-the-shelf" cell therapy applications. NK cells are highly cytolytic, and their potent antitumor effects can be rapidly triggered by a lack of HLA expression on interacting target cells, as is the case for a majority of solid tumors, including neuroblastoma. Neuroblastoma is a leading cause of pediatric cancer-related deaths and an ideal candidate for NK-cell therapy. However, the antitumor efficacy of NK cells is limited by immunosuppressive cytokines in the tumor microenvironment, such as TGFβ, which impair NK cell function and survival.

EXPERIMENTAL DESIGN

To overcome this, we genetically modified NK cells to express variant TGFβ receptors, which couple a mutant TGFβ dominant-negative receptor to NK-specific activating domains. We hypothesized that with these engineered receptors, inhibitory TGFβ signals are effectively converted to activating signals.

RESULTS

Modified NK cells exhibited higher cytotoxic activity against neuroblastoma in a TGFβ-rich environment in vitro and superior progression-free survival in vivo, as compared with their unmodified controls.

CONCLUSIONS

Our results support the development of "off-the-shelf" gene-modified NK cells, that overcome TGFβ-mediated immune evasion, in patients with neuroblastoma and other TGFβ-secreting malignancies.

Immunophenotype Anomalies Predict the Development of Autoimmune Cytopenia in 22q11.2 Deletion Syndrome

BACKGROUND

Patients with 22q11.2 deletion syndrome (22q11.2DS) may develop severe thrombocytopenic purpura and hemolytic anemia. There are no reliable predictors for the development of hematologic autoimmunity (HA) in these patients.

OBJECTIVE

To describe the peculiar B and T subpopulation defects in patients with 22q11DS who have developed HA and test if these defects precede the development of HA.

METHODS

We performed a case-control multicenter study. Patients with HA were compared with a control population of 22q11.2DS without HA (non-HA). A complete immunological evaluation was performed at diagnosis and at the last follow-up including extensive T and B phenotypes.

RESULTS

Immunophenotype at the last follow-up was available in 23 HA and 45 non-HA patients. HA patients had significantly decreased percentage of naïve CD4⁺ cells (26.8% vs 43.2%, P = .003) and recent thymic emigrants (48.6% vs 80.5%, P = .046); decreased class-switched B cells (2.0% vs 5.9%, P = .04) and increased naive B cells (83.5% vs 71.4%, P = .02); increased CD16+/56+ both in absolute number (312 vs 199, P = .009) and percentage (20.0% vs 13.0%, P = .03). Immunophenotype was performed in 36 patients (11 HA and 25 non-HA) at diagnosis. Odds ratio (OR) of immune cytopenia were estimated for both CD4 naïve ≤30% (OR 14.0, P = .002) and switched memory B cells ≤2% (OR 44.0, P = .01). The estimated survival curves reached statistical significance, respectively, P = .0001 and P = .002.

CONCLUSIONS

Among patients with 22q11.2DS, those with HA have characteristic lymphocyte anomalies that appear considerably before HA onset. Systematic immunophenotyping of patients with 22q11.2DS at diagnosis is advisable for early identification of patients at risk for this severe complication.

The Number of Regulatory B Cells is Increased in Mice with Collagen-induced Arthritis

The aim of this study is to investigate changes in regulatory B cells (Bregs) and the expression of related cytokines such as interleukin-10 (IL-10) and transforming growth factor (TGF)-β in a mouse model of collagen-induced arthritis (CIA). A total 20 DBA/1 mice (6-8 weeks old) were randomly divided into control and CIA disease groups. For the CIA disease group, animals were injected intradermally with chicken collagen type II and complete Freund's adjuvant. The calculated arthritis index score of the CIA group was significantly higher than that in control group. Hematoxylin and eosin staining showed tumid synovial cells with irregular arrangement and obvious hyperplasia, with a high degree of inflammatory cell infiltration in CIA model group. Cytometric bead array technology and quantitative RT-PCR indicated that the levels of IL-10 and TGF-β in serum, and synovial cells were significantly increased in the CIA group. The proportion of Bregs in the spleen of the CIA group was significantly increased compared to the control group. In conclusion, our findings demonstrate that the number of Bregs and the expression of TGF-β and IL-10 are enhanced in mice with CIA.

CCL21-expression and accumulation of CCR7+ NK cells in livers of patients with primary sclerosing cholangitis

The pathogenesis of primary sclerosing cholangitis (PSC), an autoimmune liver disease, remains unknown. The aim of this study was to characterize peripheral blood and intrahepatic NK cells from patients with PSC. Peripheral blood samples from patients with PSC, other autoimmune liver diseases, and from healthy control individuals were used, as well as liver tissues from PSC patients undergoing liver transplantation. Multiparameter flow cytometry showed that peripheral blood NK cells from PSC patients were significantly enriched for CCR7⁺ and CXCR3⁺ cells, and CCR7⁺ but not CXCR3⁺ cells were also significantly increased within intrahepatic NK cells. PSC patients undergoing liver transplantation furthermore had significantly higher plasma levels of the CCR7-ligand CCL21, and the CXCR3-ligands CXCL10 and CXCL11, and significantly higher levels of CCL21, but not CXCL10, were detected in liver tissues. CCR7⁺ and CXCR3⁺ NK cells from PSC patients exhibited significantly higher functional capacity in peripheral blood, but not liver tissues, consistent with chronic activation of these NK cells in the inflamed liver. These data show that PSC is characterized by intrahepatic CCL21 expression and accumulation of CCR7⁺ NK cells in the inflamed liver tissue.

Selective JAKinibs: Prospects in Inflammatory and Autoimmune Diseases

Cytokines, many of which signal through the JAK-STAT (Janus kinase-Signal Transducers and Activators of Transcription) pathway, play a central role in the pathogenesis of inflammatory and autoimmune diseases. Currently three JAK inhibitors have been approved for clinical use in USA and/or Europe: tofacitinib for rheumatoid arthritis, psoriatic arthritis and ulcerative colitis, baricitinib for rheumatoid arthritis, and ruxolitinib for myeloproliferative neoplasms. The clinical JAK inhibitors target multiple JAKs at high potency and current research has focused on more selective JAK inhibitors, almost a dozen of which currently are being evaluated in clinical trials. In this narrative review, we summarize the status of the pan-JAK and selective JAK inhibitors approved or in clinical trials, and discuss the rationale for selective targeting of JAKs in inflammatory and autoimmune diseases.

The Autoimmune Disorder Susceptibility Gene CLEC16A Restrains NK Cell Function in YTS NK Cell Line and Clec16a Knockout Mice

CLEC16A locus polymorphisms have been associated with several autoimmune diseases. We overexpressed CLEC16A in YTS natural killer (NK) cells and observed reduced NK cell cytotoxicity and IFN-γ release, delayed dendritic cell (DC) maturation, decreased conjugate formation, cell-surface receptor downregulation and increased autophagy. In contrast, siRNA mediated knockdown resulted in increased NK cell cytotoxicity, reversal of receptor expression and disrupted mitophagy. Subcellular localization studies demonstrated that CLEC16A is a cytosolic protein that associates with Vps16A, a subunit of class C Vps-HOPS complex, and modulates receptor expression via autophagy. Clec16a knockout (KO) in mice resulted in altered immune cell populations, increased splenic NK cell cytotoxicity, imbalance of dendritic cell subsets, altered receptor expression, upregulated cytokine and chemokine secretion. Taken together, our findings indicate that CLEC16A restrains secretory functions including cytokine release and cytotoxicity and that a delicate balance of CLEC16A is needed for NK cell function and homeostasis.

Autoantibodies to killer cell immunoglobulin-like receptor 3DL1 in patients with systemic lupus erythematosus

A genetic variant of the killer immunoglobulin-like receptor 3DL1 (KIR3DL1) has been found in patients with systemic lupus erythematosus (SLE). Herein, we investigated the presence of autoantibodies to KIR3DL1 in a cohort of patients with SLE. We tested sera from 28 patients with SLE, 11 patients with rheumatoid arthritis (RA) and 17 healthy control subjects for anti-KIR3DL1 activity by an enzyme-linked immunosorbent assay (ELISA) using recombinant KIR3DL1-enhanced green fluorescent protein (EGFP) and EGFP proteins. Anti-KIR3DL1 antibodies were detected in 22 (79%) of the 28 patients with SLE, whereas they were present in only three (27%) of the 11 patients with RA examined. Notably, 10 (91%) of the 11 samples from patients with SLE prior to therapy had anti-KIR3DL1 antibodies. None of the samples from healthy donors were positive for the antibodies. Here, we report the presence of anti-KIR3DL1 antibodies in the sera of patients with SLE for the first time. Anti-KIR3DL1 autoantibodies may be involved in the pathogenesis of autoimmune diseases.

Regulatory IFN-γ-producing killer dendritic cells are enhanced in B6.MLR-Faslpr /J lupus-prone mice

A novel cell population denominated IFN-γ-producing killer dendritic cells (IKDCs) have been recently described. These cells are lymphocytes lacking B- or T- receptors, but they can be identified by the presence of B220⁺ CD38⁺ CD49b⁺ and low CD11c, among other cell surface markers. The main characteristics of IKDCs are the production of IFN-γ and the ability to spontaneously kill tumor cells. We found that this population increases in B6.MLR-Fas^lpr /J mice. Interestingly, IKDCs increase with age and are more abundant in mice older than 6 months onward. To analyze whether these cells have any role in the induction of the lupus-like phenotype in the B6.MLR-Fas^lpr /J mice, IKDCs were purified and transferred into 6-month-old B6.MRL-Fas^lpr /J mice, then the presence of anti-nuclear antibodies (ANAS) and anti-dsDNA antibodies were analyzed 2 and 4 months after the transfer. The results showed a reduction in the levels of these autoantibodies and increased survival of these mice, indicating that these cells may have a regulatory function. In vitro assays demonstrated that IKDCs reduced the proliferation of both autoreactive B and T cells, suggesting that these may be the mechanisms used by these cells to ameliorate the lupus-like phenotype in the B6.MRL-Fas^lpr /J mice.

CXCR3-deficient natural killer cells fail to migrate to B16F10 melanoma cells

Natural killer (NK) cells eliminate cancer cells in a contact-dependent manner. However, how NK cells find cancer cells remain unclear. Here, using time-lapse imaging, we investigated how individual NK cells migrate toward cancer cells. Although naïve B16F10 cancer cells produce low levels of chemokines, IFN-γ-treated B16F10 cells secreted high levels of CXCL10, low levels of CCL5, but did not secrete CCL2, CCL7, or CXCL12. Wild-type NK cells migrated well toward cancer cells and killed them, whereas NK cells deficient in CXCR3 did not. CXCR3-deficient NK cells also showed slower migration speed than did wild-type NK cells. Taken together, our data show that NK cells find cancer cells, at least in part, by sensing CXCL10 produced by cancer cells and suggest that a strategy to increase CXCL10 secretion by cancer cells may improve the efficacy of NK cell-based immunotherapy.

A peptide inhibitor of antibody-dependent cell-mediated cytotoxicity against EGFR/folate receptor-α double positive cells

Antibody-dependent cell-mediated cytotoxicity (ADCC) is caused by natural killer (NK) cells upon recognition of antigen-bound IgG via FcγRIIIa. This mechanism is crucial for cytolysis of pathogen-infected cells and monoclonal antibody (mAb)-mediated elimination of cancer cells. However, there is concern that mAb-based cancer therapy induces ADCC against non-target cells expressing antigens. To date, no strategy has been reported to enhance the selectivity of ADCC to protect non-target cells expressing antigens. Here, we introduce a model inhibitor which specifically blocks ADCC of anti-EGFR mAbs towards EGFR/folate receptor α (FRα) double positive cells. This inhibitor recruits mAbs on the FRα of the cell surface independent of Fab antigen recognition. The resulting ternary and/or quaternary complexes formed on the cell surface suppress signal transduction of FcγRIIIa in NK cells, consequently leading to more specific ADCC.

Diversification of human NK cells: Lessons from deep profiling

NK cells are innate lymphocytes with important roles in immunoregulation, immunosurveillance, and cytokine production. Originally defined on the functional basis of their "natural" ability to lyse tumor targets and thought to be a relatively homogeneous group of lymphocytes, NK cells possess a remarkable degree of phenotypic and functional diversity due to the combinatorial expression of an array of activating and inhibitory receptors. Diversification of NK cells is multifaceted: mechanisms of NK cell education that promote self-tolerance result in a heterogeneous repertoire that further diversifies upon encounters with viral pathogens. Here, we review the genetic, developmental, and environmental sources of NK cell diversity with a particular focus on deep profiling and single-cell technologies that will enable a more thorough and accurate dissection of this intricate and poorly understood lymphocyte lineage.