Natural Killer Cell Deficiency Research Articles

Active juvenile systemic lupus erythematosus is associated with distinct NK cell transcriptional and phenotypic alterations

While adaptive immune responses have been studied extensively in SLE (systemic lupus erythematosus), there is limited and contradictory evidence regarding the contribution of natural killer (NK) cells to disease pathogenesis. There is even less evidence about the role of NK cells in the more severe phenotype with juvenile-onset (J)SLE. In this study, analysis of the phenotype and function of NK cells in a large cohort of JSLE patients demonstrated that total NK cells, as well as perforin and granzyme A expressing NK cell populations, were significantly diminished in JSLE patients compared to age- and sex-matched healthy controls. The reduction in NK cell frequency was associated with increased disease activity, and transcriptomic analysis of NK populations from active and low disease activity JSLE patients versus healthy controls confirmed that disease activity was the main driver of differential NK cell gene expression. Pathway analysis of differentially expressed genes revealed an upregulation of interferon-α responses and a downregulation of exocytosis in active disease compared to healthy controls. Further gene set enrichment analysis also demonstrated an overrepresentation of the apoptosis pathway in active disease. This points to increased propensity for apoptosis as a potential factor contributing to NK cell deficiency in JSLE.

Replication Stress in Activated Human NK Cells Induces Sensitivity to Apoptosis.

NK cells are innate immune effectors that kill virally infected or malignant cells. NK cell deficiency (NKD) occurs when NK cell development or function is impaired and variants in MCM4, GINS1, MCM10, and GINS4 result in NKD. Although NK cells are strongly impacted by mutational deficiencies in helicase proteins, the mechanisms underlying this specific susceptibility are poorly understood. In this study, we induced replication stress in activated NK cells or T cells by chemical and genetic methods. We found that the CD56bright subset of NK cells accumulates more DNA damage and replication stress during activation than do CD56dim NK cells or T cells. Aphidicolin treatment increases apoptosis of CD56bright NK cells through increased pan-caspase expression and decreases perforin expression in surviving cells. These findings show that sensitivity to replication stress affects NK cell survival and function and contributes to NKD.

99 C-terminal mutants in IRF8 associated with mild natural killer cell deficiency

99 C-terminal mutants in IRF8 associated with mild natural killer cell deficiency

Abstract 1339: Pre-clinical development of IAMA-004, a tri-specific antibody targeting innate immune receptors and tumor targets

Abstract Immune check-point inhibitor (ICI) such as anti-PD1 or anti-PDL1 antibody, which enhances the adaptive immunity via re-energizing exhausted T cells, has become the foundational therapy for many cancers. However, due to variety of other immunosuppressive tumor microenvironments, it is efficacious only in 15-30% of the patients. It is well known both the innate immunity and the adaptive immunity are required for full control of cancer growth. Thus, therapeutics harnessing the innate immunity will be complementary to ICI and improve the cancer response rate when used in combination. Currently therapeutics harnessing the innate immunity mainly involve bispecific antibodies with one arm targeting tumor antigen and one arm connecting to innate effector cells such as NK cells or macrophages, represented by CD30-CD16a bispecific and Her2-CD47 bispecific respectively. Considering that cancer patient’s immune status are heterogenous, varying from T cell exhaustion, macrophage disfunction (M2 bias), Treg cell presence to NK cell deficiencies, it would be advantageous to combine several innate immunity enhancers into one therapeutic molecule. Here we describe a long-acting tri-specific antibody termed IAMA-004 that targets Her2 as the primary target and CD47 and CD16a as effector cell engagers. CD47 is also a co-target on some tumor cells (CD47-Her2 double positive tumors). We have characterized this molecule both in vitro and in vivo. The in vitro experiments tested the molecule’s ability to kill Her2 high, Her2 low and Her2 negative tumor cell lines including BT-474, SK-OV-3, NCI-N87, OE19, HCC1954, MDA-MB-231, MDA-MB-468, in human PBMC ADCC assays with DS-8201 and Trastuzmab as the comparator molecules. In all of these ADCC experiments, IAMA-004 showed superior tumor cell killing activities to those mediated by DS-8201 or Trastuzmab. When combined with IAMA-005 (a Fc-IL2-IFN-α fusion cytokine), the tumor cell killing activities were dramatically increased. In addition, IAMA-004 was also tested in patient-derived Ex-Vivo fluids (one malignant pleural effusion and one malignant asities) and demonstrated tumor cell killing efficacies; and the killing activity could be attributed to the specific arms of the molecule. These results suggest that it is feasible to combine more than one innate engager in one molecule to carry out specific functions in the heterogeneous immune status for the treatment of advanced cancer patients. Citation Format: Liming Liu, Zhen Han, Yang Fan, Qi Pan. Pre-clinical development of IAMA-004, a tri-specific antibody targeting innate immune receptors and tumor targets [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1339.

Soluble MICA in endometriosis pathophysiology: Impairs NK cell degranulation and effector functions.

Endometriosis exhibits several immune dysfunctions, including deficient natural killer (NK) cell cytotoxicity. MICA (MHC class I chain-related molecule A) is induced by biological stress and soluble MICA (sMICA) negatively modulates the expression of the activating receptor, NKG2D, reducing NK cells activities. We investigated the involvement of soluble MICA in NK cell-deficient activity in endometriosis. sMICA levels (serum and peritoneal fluid-PF) were evaluated by ELISA. Circulating NK cell subsets quantification and its NKG2D receptor expression, NK cell cytotoxicity and CD107a, IFN-γ and IL-10 expressions by NK cells stimulated with K562 cells were determined by flow cytometry. We found higher sMICA levels (serum and PF) in endometriosis, especially in advanced and deep endometriosis. Endometriosis presented lower percentages of CD56dim CD16+ cytotoxic cells and impaired NK cell responses upon stimulation, resulting in lower CD107a and IFN-γ expressions, and deficient NK cell cytotoxicity. NK cell stimulation in the MICA-blocked condition (mimicking the effect of sMICA) showed decreased cytotoxicity in initial endometriosis stages and the emergence of a negative correlation between CD107a expression and sMICA levels. We suggest that soluble MICA is a potential player in endometriosis pathophysiology with involvement in disease progression and severity, contributing to NK cell impaired IFN-γ response and degranulation. NK cell compartment exhibits multiple perturbations, including quantitative deficiency and impaired cytotoxicity, contributing to inadequate elimination of ectopic endometrial tissue.

β-Actin G342D as a Cause of NK Cell Deficiency Impairing Lytic Synapse Termination.

NK cell deficiency (NKD) occurs when an individual's major clinical immunodeficiency derives from abnormal NK cells and is associated with several genetic etiologies. Three categories of β-actin-related diseases with over 60 ACTB (β-actin) variants have previously been identified, none with a distinct NK cell phenotype. An individual with mild developmental delay, macrothrombocytopenia, and susceptibility to infections, molluscum contagiosum virus, and EBV-associated lymphoma had functional NKD for over a decade. A de novo ACTB variant encoding G342D β-actin was identified and was consistent with the individual's developmental and platelet phenotype. This novel variant also was found to have direct impact in NK cells because its expression in the human NK cell line YTS (YTS-NKD) caused increased cell spreading in lytic immune synapses created on activating surfaces. YTS-NKD cells were able to degranulate and perform cytotoxicity, but they demonstrated defective serial killing because of prolonged conjugation to the killed target cell and thus were effectively unable to terminate lytic synapses. G342D β-actin results in a novel, to our knowledge, mechanism of functional NKD via increased synaptic spreading and defective lytic synapse termination with resulting impaired serial killing, leading to overall reductions in NK cell cytotoxicity.

A critical threshold of MCM10 is required to maintain genome stability during differentiation of induced pluripotent stem cells into natural killer cells.

Natural killer (NK) cell deficiency (NKD) is a rare disease in which NK cell function is reduced, leaving affected individuals susceptible to repeated viral infections and cancer. Recently, a patient with NKD was identified carrying compound heterozygous variants of MCM10 (minichromosome maintenance protein 10), an essential gene required for DNA replication, that caused a significant decrease in the amount of functional MCM10. NKD in this patient presented as loss of functionally mature late-stage NK cells. To understand how MCM10 deficiency affects NK cell development, we generated MCM10 heterozygous (MCM10+/-) induced pluripotent stem cell (iPSC) lines. Analyses of these cell lines demonstrated that MCM10 was haploinsufficient, similar to results in other human cell lines. Reduced levels of MCM10 in mutant iPSCs was associated with impaired clonogenic survival and increased genomic instability, including micronuclei formation and telomere erosion. The severity of these phenotypes correlated with the extent of MCM10 depletion. Significantly, MCM10+/- iPSCs displayed defects in NK cell differentiation, exhibiting reduced yields of hematopoietic stem cells (HSCs). Although MCM10+/- HSCs were able to give rise to lymphoid progenitors, these did not generate mature NK cells. The lack of mature NK cells coincided with telomere erosion, suggesting that NKD caused by these MCM10 variants arose from the accumulation of genomic instability including degradation of chromosome ends.

Association of NK cell subsets and cytotoxicity with FCGR3A gene polymorphism in functional NK cell deficiency.

The purpose of this study was to assess the association between clinical, laboratory, and functional analyses and polymorphism in the FCGR3A gene in individuals with functional NK cell deficiency. A total of 15 functional NK cell deficiency patients and 10 age-matched healthy controls underwent NK cell subgroup, cytotoxicity, and FCGR3A whole-exome analysis with next-generation sequencing. Three different NK cell subsets (CD56brightCD16neg, CD56brightCD16int, and CD56dimCD16hi) were identified. No statistically significant difference was found in the ratio of CD56brightCD16neg cells between patients and controls. CD56brightCD16int and CD56dimCD16hi ratios were found to be significantly lower in patients. As a result of NK cell cytotoxicity analysis, a proportional decrease of K562 amount between patients and controls was found to be statistically significant (p<0.001). In the FCGR3A whole-exome analysis, all patients were found to be homozygous mutant for the c.526G > T (p.V176F) in exon 4, while three patients were homozygous wild type and 12 patients were heterozygous for the c.197T>A (p.L66H) in exon 3. In this study, a group of pediatric patients with suspected functional NK cell deficiency were evaluated and the findings indicated that NK subsets, cytotoxicity results, and FCGR3A gene polymorphism were found to be correlated with the clinical features. We conclude that this kind of study might contribute to follow-up the patients in time.

Altered NCR3 Splice Variants May Result in Deficient NK Cell Function in Renal Cell Carcinoma Patients.

The natural killer (NK) cell function of patients with malignant tumours may be suppressed by deficiency, and the poor prognosis of renal cell carcinoma (RCC) patients may be due to escape from NK cell cytotoxicity, especially with respect to natural cytotoxicity receptors (NCRs) on the NK cell surface. However, the specific mechanism remains unclear. Therefore, in this study, we sought to explore the role of NCR, especially NCR3 splice variants, in the process of NK cell deficiency in RCC patients. We used flow cytometry to analyse the phenotype of NK cells from the peripheral blood and kidney tumour tissue of RCC patients. The NKp30-mediated NK cell killing function was measured by antibody-dependent cell-mediated cytotoxicity (ADCC) in NK and RCC cell coincubation. We extracted RNA from the peripheral blood mononuclear cells (PBMCs) of RCC patients and renal carcinoma tissue and carried out real-time quantitative PCR to detect the mRNA levels of NKp30a, NKp30b and NKp30c. mRNA expression levels of cytokines (IL-6, IL-8, IL-10, IL-18 and TGF-β) based on RNA extracted from renal carcinoma tissue and adjacent normal kidney tissues were also measured by real-time quantitative PCR. Regarding the phenotype of NK cells in RCC patients, the proportion of NK cells in tumour tissue was significantly reduced, with changes in the NK cell proportion being most obvious in NKp30+ NK cells. Furthermore, the results of the ADCC function assay showed limited NKp30+ NK cell-mediated cytotoxicity in RCC patients. Through real-time quantitative PCR, we found lower expression of NKp30a and NKp30b, the immunostimulatory splice variants of NCR3 encoding NKp30, in RCC patients. Moreover, expression of activating cytokines (IL-6 and IL-8) in renal cancer tissue was decreased, though inhibitory cytokine (TGF-β) expression remained unchanged, which may result in an immunosuppressive cytokine microenvironment. Decreased expression of immunostimulatory NCR3 splice variants and the inhibitory cytokine microenvironment in RCC patients may contribute to deficient NK cell cytotoxicity and renal carcinoma cell immune escape from NK cell killing, which may provide a theoretical basis for finding new immunotherapeutic targets for RCC.

PRDM1 Promotes Primary Human Circulating CD56 dim NK-Cell Differentiation

Background: Natural killer (NK) cells are innate lymphocytes that mount immune responses against viral infection and malignant cells. Circulating NK-cells can be generally divided into two groups, CD56 bright and CD56 dim, with the latter constituting ~90% of NK-cells in peripheral blood. While CD56 bright NK-cells are considered less mature and capable of producing more cytokines, CD56 dim population represents more differentiated cells with greater cytotoxicity. Transcription factor (TF) regulatory circuits were proposed for CD56 bright and CD56 dim NK-cells, indicating that TCF1/LEF1 and BACH2 are important in the former population and that Blimp1 and MAF are master TFs in the latter group. Blimp1 (encoded by PRDM1) has been previously found to regulate terminal differentiation of B-cells and CD8 + T-cells. In NK-cells, deletion of PRDM1 has been shown to promote cell growth and survival in vitro, and its loss of function was commonly detected in NK-cell lymphomas. Here, we employed a multi-omics approach to investigate the role of PRDM1 in the differentiation of human primary NK-cells. Methods: We used CRISPR-Cas9 system to knock out PRDM1 in primary human NK-cells isolated from PBMCs of healthy donors and performed whole transcriptome sequencing. ChIP-seq was employed to investigate the global binding spectrum of PRDM1 in primary human NK-cells cultured with K562-mbIL21-Cl9 feeder cells or with IL-2 alone. We also performed integrative genomics analyses to examine the transcriptomic regulation of NK-cell differentiation by PRDM1. Results: Gene set enrichment analyses (GSEA) demonstrated that PRDM1 KO resulted in enrichment of genes highly expressed in CD56 bright cells and depletion of genes upregulated in CD56 dim NK-cells. Specifically, we found that PRDM1 deficient NK-cells expressed CD56 bright NK-cell master TFs at higher levels, such as TCF7, RUNX2, and MYC. In contrast, TFs that play an important role in more differentiated CD56 dim NK cells were downregulated in PRDM1-KO cells, including IKZF3, MAF, and TBX21. Notably, BCL11B, a TF that has been reported to promote canonical and adaptive NK-cell differentiation, was significantly downregulated along with its target gene ZBTB16 when PRDM1 was deleted. Moreover, genes encoding cytotoxic molecules such as PRF1 and GZMB were also repressed in PRDM1-KO NK-cells. Together, these results indicate that PRDM1-KO NK-cells closely resembled the less mature CD56 bright NK-cells than the CD56 dim terminally differentiated counterpart. ChIP-seq analysis of PRDM1 revealed that many of the differentially expressed genes (DEGs) between PRDM1 KO and WT cells were directly bound by PRDM1. When integrated with publicly available ATAC-seq datasets, we found that some of these PRDM1 bound sites showed differential chromatin accessibility between CD56 bright and CD56 dim NK-cells. To explore the transcriptional program regulated by PRDM1, we utilized a regulated system to re-express PRDM1 in KHYG1, an NK-cell lymphoma cell line that is sensitive to PRDM1 overexpression. RNA-seq analysis showed that the DEGs between KHYG1 with short-term re-expression of PRDM1 and control cells overlapped with DEGs between PRDM1 KO vs WT NK-cells. These genes included BCL11B, MAF, PRF1, and GZMB. Therefore, PRDM1 directly regulates genes that are crucial in NK-cell differentiation. Furthermore, we detected upregulation of memory T-cell or progenitor exhausted T-cell signature genes in PRDM1 KO NK-cells compared with WT, including TCF7, SELL, CCR7, and IL7R. Consistent with this, GSEA analysis demonstrated enrichment of TCF1 + progenitor exhausted T cell or memory T cell upregulated genes in PRDM1 deleted NK-cells, suggesting that PRDM1 KO NK-cells may share some features with memory T-cells or progenitor exhausted T cells. Importantly, MYB, which was found to be essential in progenitor exhausted T cells, was also a direct target of PRDM1 and was upregulated in PRDM1 KO NK-cells. GSEA also showed that PRDM1 depletion in NK-cells led to upregulation of genes highly expressed in mast cell, Th1 cell, B cell, or CD8 + T cell compared to NK cells, which may indicate a role of PRDM1 in maintaining lineage commitment. Conclusions: Our findings collectively show that PRDM1 may be a master TF that regulates human NK-cell differentiation and functions through direct transcriptional regulation of key target genes.

GATA2-TAL1 Axis Is Essential for Human NK Cell Development and Function

Introduction: Natural killer (NK) cells, as the major subset of innate lymphocytes, produce proinflammatory cytokines and mediate anti-tumor cytotoxicity (1-3). Since NK cells are not limited by clonotypic receptors, they can be utilized in cell therapies against a broad spectrum of malignancies. Irrespective of the clinical potentials, the transcriptional regulation of the development and functions of human NK cells is far from fully understood. A dysregulated NK cell development is a hallmark of GATA2 haploinsufficiency (4)(eg. GATA2 T354M mutation). The specific loss of the CD56 bright NK cell population is a significant striking feature in GATA2-deficient patients (4), with or without reduced total CD56 dim NK cells (4, 12, 13). Consequently, the effector functions of these NK cells are significantly reduced, including inflammatory cytokine production and anti-tumor cytotoxicity (4, 12). However, a mechanistic understanding of GATA2 functions is lacking. In humans, GATA2 forms a core heptad complex with six other transcription factors (TF), including TAL1, regulating more than 1000 target genes. However, the unique functions of the GATA2-TAL1 axis in immature and mature NK cell has not been established. Based on these, we hypothesize that GATA2-dependent and independent functions of TAL1 play an essential role in the development and functions of human NK cells. Results: To explore the mechanism of co-transcriptional regulation of GATA2 and TAL1, we transduced NK-92 cells with lentiviral vectors containing GATA2 WT or GATA2 T354M plasmid and quantified TAL1 mRNA levels by qPCR and protein levels by WB. TAL1 is upregulated in GATA2 T354M-expressing NK-92 cells both at mRNA ( Fig. 1A) and protein levels ( Fig. 1B). TAL1 is a TF activating GTPase of immunity-associated protein (GIMAP) family super-enhancer regions in HSC and T cells (11). As TAL1 target genes, we further quantify GIMAP mRNA levels by qPCR. The result indicates that genes from the GIMAP family were notably upregulated in GATA2 T354M-expressing NK-92 cells ( Fig. 1C). Knocking down TAL1 results in the significant downregulation of TAL1 and GIMAPs in GATA2 T354M-expressingcells ( Fig. 1D). To further validate the GATA2-TAL1 axis, sorted NK cells from PBMCs of three GATA2 T354M patients and five age-matched healthy controls (HC) were analyzed with single-cell RNA-seq. We identified the genes from GIMAP family were significantly upregulated in all three GATA2 T354M patients. The representative data from one patient is shown in Fig. 1E. To explore how GATA2 and TAL1 mediate transcriptional regulation, we performed GATA2 CUT&amp;Tag experiments with human NK cells, in which TAL1 motif was predominately enriched in 63.2% of GATA2 targets among NK cells through HOMER motif enrichment analyses ( Fig. 1F). On the other hand, the TAL1 ChIP-seq data from the K562 cells (download from ENCFF101DBG) reveals that the GATA2 motif is enriched in approximately 44% of TAL1 targets ( Fig. 1G). Moreover, both GATA2 and TAL1 expression in NK cells are modified by H3K27Me3 instead of H3K4Me3, suggesting a repressive methylenation signature in their expression ( Fig. 1H). Conclusion: Based on this study, we uncover a novel role for the GATA2-TAL1 axis in human NK cells. we define the transcriptional regulation role of GATA2 and TAL1 complex and provide direct evidence for the mechanism of NK cell deficiency among GATA2 T354M patients. Importantly, through our current study, we will determine the unique role of TAL1 in NK development and function and its transcriptional network.

Toxoplasma gondii Causes Adverse Pregnancy Outcomes by Damaging Uterine Tissue-Resident NK Cells That Secrete Growth-Promoting Factors.

Vertical transmission of the intracellular parasite, Toxoplasma gondii can lead to adverse pregnancy outcomes especially when infection occurs in early pregnancy. Decidual natural killer (dNK) cells accumulate at the maternal-fetal interface in large numbers during early pregnancy. Their nutritional roles during infection with T. gondii remain poorly defined. In the present study, we demonstrated that a functional deficiency of the uterine tissue-resident NK (trNK) cells, a subset of dNK cells, contributes to the adverse pregnancy outcomes induced by T. gondii in early pregnancy. Adverse pregnancy outcomes could be ameliorated by adoptive transfer of trNK cells. Moreover, fetal growth restriction could be improved after supplementation of growth-promoting factors. In addition to the widely recognized disturbance of the immune balance at the interface between the mother and the fetus, our study reveals a novel mechanism in T. gondii that contributes to the adverse pregnancy outcomes.

Acid-switchable nanoparticles induce self-adaptive aggregation for enhancing antitumor immunity of natural killer cells.

Deficiency of natural killer (NK) cells shows a significant impact on tumor progression and failure of immunotherapy. It is highly desirable to boost NK cell immunity by upregulating active receptors and relieving the immunosuppressive tumor microenvironment. Unfortunately, mobilization of NK cells is hampered by poor accumulation and short retention of drugs in tumors, thus declining antitumor efficiency. Herein, we develop an acid-switchable nanoparticle with self-adaptive aggregation property for co-delivering galunisertib and interleukin 15 (IL-15). The nanoparticles induce morphology switch by a decomposition-metal coordination cascade reaction, which provides a new methodology to trigger aggregation. It shows self-adaptive size-enlargement upon acidity, thus improving drug retention in tumor to over 120h. The diameter of agglomerates is increased and drug release is effectively promoted following reduced pH values. The nanoparticles activate both NK cell and CD8+ T cell immunity invivo. It significantly suppresses CT26 tumor in immune-deficient BALB/c mice, and the efficiency is further improved in immunocompetent mice, indicating that the nanoparticles can not only boost innate NK cell immunity but also adaptive T cell immunity. The approach reported here provides an innovative strategy to improve drug retention in tumors, which will enhance cancer immunotherapy by boosting NK cells.

CDC45 haploinsufficiency as a novel cause of natural killer cell deficiency

Natural killer cell deficiency (NKD) is a primary immunodeficiency where natural killer cells are the primary lineage affected. Individuals with NKD present with malignancies and susceptibility to viral infection, especially from the Herpesviridae family. Though NKD is rare, four genes that are involved in the CDC45-MCM-GINS (CMG) helicase have been described to result in NKD, including MCM4, GINS1, MCM10, and GINS4. The CMG helicase is critical for eukaryotic replication and plays a critical role in maintaining genomic stability. To our knowledge, CDC45 has never been described as a monogenic cause of NKD. However, here we describe a single damaging heterozygous variant in CDC45 in an individual with consistent defects in the NK cell compartment. This individual has a disruption in the ratio of CD56bright to CD56dim cells, severely decreased frequency of adaptive NK cells, and decreased NK cell cytotoxic function. As previously reported for other helicase variants that cause NKD, we found cell cycle defects, increased DNA damage, and impaired DNA damage repair signaling in patient lymphocytes. The description of CDC45 as a cause of NKD contributes to our understanding of the role of the CMG helicase in NK cell maturation, function, and biology.

Differential sensitivity to replication stress of human NK cells

Abstract Natural killer cells are critical components of the innate immune system that kill virally infected or malignant cells. Though rare, natural killer cell deficiency (NKD) occurs when NK cell development and function are impaired and individuals with NKD are susceptible to severe and recurrent viral infections. Several gene deficiencies have been described to result in NKD, including variants in MCM4, GINS1, MCM10and GINS4, which are components of the CMG helicase. The helicase unwinds DNA during replication and is found in any actively proliferating cell. NK cells are more strongly impacted by mutational deficiencies in helicase proteins than other lymphocytes, though the mechanisms underlying this are not completely understood. NK cells from individuals with NKD as a result of helicase deficiency have increased DNA damage, cell cycle arrest, and replication stress. Here, we induced replication stress during NK or T cell specific activation by chemical methods, using aphidicolin, and genetic methods like siRNA targeting helicase proteins. We found that the CD56 brightsubset of NK cells accumulates more DNA damage and replication stress during activation than CD56 dimNK cells or activated T cells. The drug aphidicolin increases apoptosis of CD56 brightNK cells through caspase activation while simultaneously decreasing intracellular perforin expression, a protein important for killing of target cells. This effect is modeled by siRNA mediated knockdown of CMG proteins, thus linking decreased protein expression to replication stress and impaired NK cell function. These findings lend important insight into the mechanisms by which helicase deficiencies selectively affect human NK cell function and cause NK cell deficiency. NIH R01A137275

New syndromic combined immunodeficiency with severe neurodevelopmental defects caused by biallelic null variants in the PPM1D gene

PPM1D (protein phosphatase Mn2+/Mg2+-dependent 1D) is a phosphatase that targets proteins related to the DNA damage repair system. C-terminal variants in PPM1D have been associated with: i) malignancy as somatic variants; and ii) Jansen-de-Vries (JdV) syndrome as germline heterozygous variants. JdV syndrome curses with moderate neurodevelopmental alterations and behavioral problems, such as autistic spectrum disorders (ASD), without reports of immunodeficiency.We describe two siblings (9 and 11 years old) born to consanguineous parents with progressive B and NK cell lymphopenia, agammaglobulinemia, non-ulcerative colitis and severe neurodevelopmental defects including microcephaly, severe encephalopathy, profound cognitive deficiency, and refractory epilepsy. Exome analysis revealed a homozygous N-terminal truncating variant in PPM1D (p.Thr174fs*6) in the two siblings inherited from their healthy heterozygous parents. The siblings’ clinical phenotype was markedly more severe than in the reported JdV patients, suggesting a different mechanism of action. To test this, we included a pediatric patient with classical JdV syndrome carrying an heterozygous PPM1D variant (p. Ser403fs*30). Using primary cells and exogenous overexpression we showed that mutation p.T174fs*6 abrogated protein expression by increased proteasome degradation, leading to no protein expression in a homozygous patient and a reduction in a haplosufficient parent. In contrast, the JdV variant (p.Ser403fs*30) led to accumulation of the truncated protein with conserved phosphatase activity, resulting in a previously undescribed gain-of-function (GOF) mechanism.We also demonstrated that chemical inhibition of WT-PPM1D in-vitro dramatically decreased B cell viability. This data, similar to the reported B cell deficiency in PPM1D-KO mice, helps to address the humoral deficiency in the patients, while not observed in the heterozygous parents nor JdV patient. To further explore NK cell deficiency, we will evaluate PPM1D-KO mice. We have generated EBV-B cell-derived iPSCs from PPM1D-null, PPM1D-haplosufficient an GOF-JdV individuals, to generate artificial cerebral organoids that will allow us to explore PPM1D gene-dosage effect in neurodevelopment and its potential manipulation.Here we report a novel biallelic PPM1D-null deficiency impairing B cell development. Besides, PPM1D dysregulation either by no protein expression or GOF appears to cause neurodevelopment abnormalities. Future studies will help to understand pathophysiology of PPM1D and better targeted clinical management.PPM1D research interest group:JF Quesada1, Mercè Bolasell2, Julie E. Niemela3, Jennifer L. Stoddard3, Agustin Gil Silva3, Brigette Boast3, José R Regueiro4, Pierre Martine5, David Lopez Perez5, Ettore Appella5, Laia Alsina6,7,8, Harry L Malech9, Hye Sun Kuehn3, Sergio D. Rosenzweig31. Department of Genetics, Hospital Universitario 12 de Octubre, Madrid, Spain.2. Department of Genetic and Molecular Medicine IPER, Institut de Recerca, Hospital Sant Joan de Déu Barcelona, Barcelona, Spain.3. Immunology Service, Department of Laboratory Medicine, Clinical Center, NIH, Bethesda, Maryland, USA4. Department of Immunology, Complutense University School of Medicine and Hospital 12 de Octubre Health Research Insitute, Madrid, Spain5. Laboratory of Cell Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892.6. Clinical Immunology and Primary Immunodeficiencies Unit. Allergy and Clinical Immunology Department. Hospital Sant Joan de Déu. Barcelona, Spain.7. Clinical Immunology Unit. Hospital Sant Joan de Déu-Hospital Clinic. Barcelona, Spain.8. Study Group for Immune Dysfunction Diseases in Children (GEMDIP). Institut de Recerca Sant Joan de Déu. Barcelona, Spain.9. Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, MD.

Recombinant Human Interleukin-2 Corrects NK Cell Phenotype and Functional Activity in Patients with Post-COVID Syndrome.

Post-COVID syndrome develops in 10-20% of people who have recovered from COVID-19 and it is characterized by impaired function of the nervous, cardiovascular, and immune systems. Previously, it was found that patients who recovered from infection with the SARS-CoV-2 virus had a decrease in the number and functional activity of NK cells. The aim of the study was to assess the effectiveness of recombinant human IL-2 (rhIL-2) administered to correct NK cell phenotype and functional activity in patients with post-COVID syndrome. Patients were examined after 3 months for acute COVID-19 of varying severity. The phenotype of the peripheral blood NK cells was studied by flow cytometry. It was found that disturbances in the cell subset composition in patients with post-COVID syndrome were characterized by low levels of mature (p = 0.001) and cytotoxic NK cells (p = 0.013), with increased release of immature NK cells (p = 0.023). Functional deficiency of NK cells in post-COVID syndrome was characterized by lowered cytotoxic activity due to the decreased count of CD57+ (p = 0.001) and CD8+ (p < 0.001) NK cells. In the treatment of patients with post-COVID syndrome with recombinant IL-2, peripheral blood NK cell count and functional potential were restored. In general, the effectiveness of using rhIL-2 in treatment of post-COVID syndrome has been proven in patients with low levels of NK cells.

Cooperative actions of natural killer cells and invasive trophoblast cells at the uterine-placental interface

Natural killer (NK) and invasive trophoblast (IT) cells facilitate the establishment of the uterine-placental interface by transforming the uterus into a hospitable site for fetal development. NK cells act first followed by IT cells. These dynamics are conserved in human and rat hemochorial placentation. Herein, we utilize mutant rat models to investigate contributions of NK and IT cells in establishment of the uterine-placental interface and pregnancy outcomes. NK and IT cell deficiencies were established by disruptions of interleukin 15 (Il15) and placenta specific 1 (Plac1) loci in rat, respectively. Pregnancies with homogenous placental genotypes/phenotypes were analyzed. Four different breeding combinations were used to generate wild type, NK cell deficient, IT cell deficient, and NK-IT cell double-deficient pregnancies. Pregnancies were examined on gestation days (gd) 7.5, 13.5, 15.5, and 18.5. Viability and uterine-placental interface integrity were determined using structural and molecular/biochemical approaches. Viability and litter size did not differ among the breeding combinations at gd 7.5. At gd 13.5 and 15.5, maternal NK cell deficiency was associated with an acceleration of deep endovascular IT cell invasion into the uterine-placental interface. PLAC1 deficiency resulted in placentomegaly and absence of intrauterine interstitial IT cells, which resulted in the retention/expansion of NK cells in the uterine-placental interface. Double-deficient pregnancies exhibited fetal growth restriction, a significant decrease in fetal survival, increased maternal mortality, and compromised postnatal offspring survival. These experiments highlight the cooperative roles of NK and IT cells in ensuring a healthy pregnancy. They work together to facilitate uterine vascular remodeling and the essential delivery of nutrients to the placenta and fetus for a successful pregnancy outcome. Failures in the collective contributions of NK and IT cells adversely affect plasticity and lead to disease states associated with placentation, fetal development, and maternal wellbeing.

TLR8 agonist partially improves IFN-γ deficiency of NK cells in chronic hepatitis B through the synergy of monocytes.

Natural killer (NK) cells exhibit a selective deficiency of IFN-γ production in chronic hepatitis B (CHB). Toll-like receptor 8 (TLR8) agonists could induce IFN-γ production in immune cells, although their effects on the deficiency in NK cells remain unclear. To investigate TLR8 expression in NK cells and the effect of TLR8 agonists in patients with CHB METHODS: We enrolled 32 patients with CHB and 19 healthy controls to assess TLR8 expression and IFN-γ production in NK cells. The sorted NK cells and monocytes were co-cultured to compare the extent of IFN-γ and IL-10 production after TLR8 agonist ssRNA40 stimulation. The synergic effect of NK cells and monocytes was assessed by blocking IL-12 and IL-18. We recruited another22 patients with CHB undergoing nucleotide analogue (NA) therapy to explore the impact of antiviral treatment on the ssRNA40-mediated response of NK cells. In patients with CHB, TLR8 expression in NK cells was up-regulated, accompanied by insufficient IFN-γ production. The enhanced IFN-γ secretion by ssRNA40 in NK cells depended on monocyte-derived IL-12 and IL-18. NK cells displayed an imbalanced response to ssRNA40 in patients with CHB with a weak increase in IFN-γ despite a higher IL-10 production. The response was improved in patients with CHB undergoing NA therapy. In patients with CHB, targeting TLR8 partially rescues the IFN-γ insufficiency in NK cells.However, NK cells show an inhibitory response to TLR8 agonist stimulation. TLR8 agonist combined with NA may enhance the antiviral effect of NK cells.

An ELF4 hypomorphic variant results in NK cell deficiency.

NK cell deficiencies (NKD) are a type of primary immune deficiency in which the major immunologic abnormality affects NK cell number, maturity, or function. Since NK cells contribute to immune defense against virally infected cells, patients with NKD experience higher susceptibility to chronic, recurrent, and fatal viral infections. An individual with recurrent viral infections and mild hypogammaglobulinemia was identified to have an X-linked damaging variant in the transcription factor gene ELF4. The variant does not decrease expression but disrupts ELF4 protein interactions and DNA binding, reducing transcriptional activation of target genes and selectively impairing ELF4 function. Corroborating previous murine models of ELF4 deficiency (Elf4-/-) and using a knockdown human NK cell line, we determined that ELF4 is necessary for normal NK cell development, terminal maturation, and function. Through characterization of the NK cells of the proband, expression of the proband's variant in Elf4-/- mouse hematopoietic precursor cells, and a human in vitro NK cell maturation model, we established this ELF4 variant as a potentially novel cause of NKD.