Balancing act: the complex role of NK cells in immune regulation

SITC perspective: leveraging patient enrichment biomarkers to accelerate early phase IO drug development

Cancer immunotherapy (IO) enables patients to live well with cancer for many years, or even be cured. Several investigational IO agents recently failed in early-phase or late-phase trials, leading some to doubt the future of IO. Patient heterogeneity (eg, tumor characteristics, treatment history) increases the risk that a clinically active IO drug might be discarded. Enriching enrollment for patients with biomarkers hypothesized to reflect a higher probability of clinical benefit across clinical development should mitigate this risk. The Society for Immunotherapy of Cancer convened diverse IO stakeholders to discuss leveraging biomarkers at the earliest stages of drug development to accelerate the delivery of innovative IO agents to patients. This group developed a framework based on a biomarker-based enrichment strategy in early trials that evolves into the development of more precise predictive biomarkers in late phase trials. This framework integrates mechanistic insights related to the drug and its impact on the tumor microenvironment derived from preclinical data, digital pathology, exploratory multiomics, and artificial intelligence that are continuously refined through both adaptive and randomized clinical trials. Biomarker-based enrichment in early clinical development should de-risk late-stage trials, ultimately expanding the portfolio of innovative IO drugs available to patients.

Plasmodium and Host Immunity: Evasion Strategies and Advances in Malaria Vaccination

Malaria is an infectious disease caused by parasites of the Plasmodium genus. Its pathophysiology is highly complex, as it depends both on the host's immune response and the parasite's evasion mechanisms, which are often species-specific. This complexity has posed significant challenges to vaccine development and malaria control. Therefore, the aim of this review is to describe the host's immunological mechanisms, the parasite's evasion strategies and the available vaccines, as well as their relationship with the human immune response in controlling Plasmodium infection.

The roles of natural killer cells in bone and arthritic disease: a narrative review

The skeletal system is responsible for the body's support and motor functions, and can be pathologically affected by factors, such as metabolism, autoimmune inflammation, tumors, and infections. Regarding tissue localization and biological function, the immune system is deeply involved in the physiological and pathological processes of the skeletal system. As a regulator and effector cell of the innate immune system, natural killer (NK) cells can exert cytotoxic effects through cell contact and immunomodulatory effects through cytokine secretion. In the past 30 years, many advances have been made regarding the role of NK cells and their derived cytokines on bone and joints. In this review, the role of NK cells in the physiological activities of bone remodeling is summarized first, focusing on osteoclast differentiation and function. Subsequently, the roles of NK cells in osteoarthritis, bone tumors, and bone diseases caused by microbial infections are described, meanwhile, some conflicting research results are discussed. By reviewing the state-of-the-art progress of NK cells in the above-mentioned bone physiological and pathological processes, it is helpful to clarify the blind spots of current research and provide some references for the integrated evaluation of immune factors in the study of skeletal system diseases.

A Comprehensive Review of Long Non-Coding RNAs in the Cancer-Immunity Cycle: Mechanisms and Therapeutic Implications

Long non-coding RNAs (lncRNAs) have emerged as pivotal regulators of the dynamic interplay between cancer progression and immune responses. This review explored their influence on key processes of the cancer-immunity cycle, such as immune cell differentiation, antigen presentation, and tumor immunogenicity. By modulating tumor escape from the immune response, therapeutic resistance, and tumor-stroma interactions, lncRNAs actively shape the tumor microenvironment. Due to their growing knowledge in the area of immune suppression, directly intervening in the induction of regulatory T cells (Tregs), M2 macrophages, and regulating immune checkpoint pathways such as PD-L1, CTLA-4, and others, lncRNAs can be considered promising therapeutic targets. Advances in single-cell technologies and immunotherapy have significantly expanded our understanding of lncRNA-driven regulatory networks, paving the way for novel precision medicine approaches. Ultimately, we discussed how targeting lncRNAs could enhance cancer immunotherapy, offering new avenues for biomarker discovery and therapeutic intervention.

Th2 predominance and decreased NK cells in patients with hereditary angioedema

Background

In this study we included patients with hereditary angioedema (HAE) caused by decreased levels of C1 inhibitor (HAE-C1INH). An increased risk of autoimmune disorders, particularly systemic lupus erythematosus (SLE), has been reported in HAE-C1INH. This suggests that complement consumption affects adaptive immunity.

Objective

To investigate lymphocyte subpopulations in relation to disease activity and complement activation in HAE-C1INH patients and matched controls.

Methods

Flow cytometry of peripheral blood lymphocyte populations, measurements of complement and complement fragments, and collection of clinical data.

Results

NK cell counts were lower in HAE-C1INH patients, and their frequencies were related to disease activity. The T helper (Th) cell balance was skewed towards more Th2 cells and less Th1 cells in HAE-C1INH patients compared to controls. There were also lower frequencies of class-switched B cells and plasmablasts in patients. Levels of C4 and the complement activation fragment C3d were related to disease activity.

Conclusions

Blood lymphocyte populations are altered in HAE-C1INH, a finding which may be of pathophysiological importance considering the increased risks of both autoimmunity and allergy associated with HAE-C1INH.

Hepatic alveolar echinococcosis infection induces a decrease in NK cell function through high expression of NKG2A in patients

Echinococcus multilocularis larval tapeworm infection in humans is considered a serious public health issue. The immune interaction between parasites and their hosts is extremely important. NK cells are known innate immune cells that play important roles during infection and tumour progression. However, the possible role of NK cells in hepatic alveolar echinococcosis is not completely clear. In this study, we investigated the functional decrease in NK cells in hepatic alveolar echinococcosis (AE) patients.

Methods

Using human liver tissue samples from 10 patients with hepatic AE, flow cytometry was used to detect the expression of NKG2A molecules on the surface of NK cells, and the correlations between NKG2A+ expression and lesion size, alkaline phosphatase (ALP) levels in close lesion tissues (CLTs) and distal lesion tissues (DLTs) in the liver, and the secretion of functional molecules by NKG2A+ NK cells were analysed.

Results

The expression of NKG2A on CD56dim and CD56bright NK cells in DLTs and CLTs revealed that the percentage of NKG2A+CD56dim NK cells in CLTs was significantly greater than that in DLTs. There was a negative correlation between the expression of NKG2A on NK cells in the CLT and alkaline phosphatase. Additionally, we analysed IFN-γ, TNF-α, granzyme B, and perforin production in NK cells. There was a significant reduction in IFN-γ production in CLTs compared with DLTs. There is a negative correlation between IFN-γ production levels and NKG2A expression in NK cells from the CLT. The capacity of NKG2A+ NK cells from CLT regions to produce IFN-γ and granzyme B was also significantly decreased. In contrast, the perforin level produced by NKG2A+ NK cells was much greater than that produced by NKG2A- NK cells. We also analysed the correlation between the ratio of the NKG2A expression area in CLT and DLT tissues and the PET-CT value and found a positive correlation between NKG2A expression and the PET-CT value.

Conclusion

The increased expression of NKG2A in NK cells induced a reduction in IFN-γ production, and the increased expression of NKG2A may improve lesion activity and fibrosis, which may be helpful for treating hepatic alveolar echinococcosis via immunity.

Food, Health, and Environmental Impact of Lactic Acid Bacteria: The Superbacteria for Posterity

Lactic acid bacteria (LAB) are Gram-positive cocci or rods that do not produce spores or respire. Their primary function is to ferment carbohydrates and produce lactic acid. The two primary forms of LAB that are currently recognized are homofermentative and heterofermentative. This review discusses the evolutionary diversity and the biochemical and biophysical conditions required by LAB for their metabolism. Next, it concentrates on the applications of these bacteria in gut health, cancer prevention, and overall well-being and food systems. There are numerous uses for LAB, including the food and dairy sectors, as probiotics to improve human and animal gut-health, as anti-carcinogenic agents, and in food safety as biopreservatives, pathogen inhibitors, and reducers of anti-nutrients in foods. The group included many genera, including Aerococcus, Carnobacterium, Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Streptococcus, Tetragenococcus, Vagococcus, and Weissella. Numerous species of Lactobacillus and Bifidobacterium genera as well as other microbes have been suggested as probiotic strains, or live microorganisms added to meals to improve health. LAB can colonize the intestine and take part in the host's physiological processes. This review briefly highlights the role of these bacteria in food safety and security as well as aspects of regulation and consumer acceptance. Finally, the recent innovations in LAB fermentations and the limitations and challenges of the applications of LAB in the food industry are discussed. Notwithstanding recent developments, the study of LAB and their functional components is still an emerging topic of study that has not yet realized its full potential.

An overview of host immune responses against Leishmania spp. infections

Leishmania spp. infections pose a significant global health challenge, affecting approximately 1 billion people across more than 88 endemic countries. This unicellular, obligate intracellular parasite causes a spectrum of diseases, ranging from localized cutaneous lesions to systemic visceral infections. Despite advancements in modern medicine and increased understanding of the parasite's etiology and associated diseases, treatment options remain limited to pentavalent antimonials, liposomal amphotericin B, and miltefosine. A deeper understanding of the interactions between immune and non-immune cells involved in the clearance of Leishmania spp. infections could uncover novel therapeutic strategies for this debilitating disease. This review highlights recent progress in elucidating how various cell types contribute to the regulation and resolution of Leishmania spp. infections.

Immunological Disorders: Gradations and the Current Approach in Laboratory Diagnostics

Currently, understanding the immune response, its abnormalities, and its diagnostic possibilities is a key point in the management of patients with various diseases, from infectious to oncological ones. The aim of this review was to analyze the data presented in the current literature on immune disorders and the possibility of their laboratory diagnostics in combination with clinical manifestations. We have performed a systematic analysis of the literature presented in international databases over the last ten years. We have presented data on the possibility of diagnosing immunopathological processes due to changes in immune cells and soluble molecules involved in the pathogenesis of a wide range of diseases, as well as the determination of antibodies to detect autoimmune processes. By applying laboratory techniques such as hematology, flow cytometry, ELISA, etc., available to most clinical laboratories worldwide, clinical data on immune system dysfunction in a wide range of diseases are being collected. This process is unfortunately still very far from being completed. However, with all the diversity of accumulated knowledge, we can currently state that the pathogenesis of the vast majority of immune-mediated diseases is not yet known. At the same time, the current success in dividing immune-mediated diseases into distinct clusters based on different types of inflammatory responses that are based on the involvement of different populations of T helper cells and cytokine molecules represents significant progress. Further research in this direction seems very promising, as it allows the identification of new target cells and target molecules for both improved diagnostics and targeted therapies.

Immunomodulatory effects of supercritical CO2 extracted oils from Portulaca oleracea and Perilla frutescens (PPCE) in healthy individuals: a randomized double-blind clinical trial

The human immune system plays a crucial role in defending the body against various infections, viruses, and external substances, contributing to overall well-being. However, an imbalance in the immune system can lead to increased susceptibility to infections, impacting overall health. Preclinical investigations suggest the potential application of Portulaca oleracea L. and Perilla frutescens var. japonica Hara seed complex extract (PPCE) as a potent biological response modifier in terms of immunity. However, the safety and efficacy of PPCE in boosting immune function have not been investigated clinically. The present study aims to evaluate the safety and efficacy of PPCE on the immune system in healthy adults. An 8-week randomized, double-blinded, placebo-controlled cross-over clinical trial was adopted for the study. Study participants were administered either 1080 mg day-1 of a PPCE supplement or a placebo. The study assessed the Natural Killer (NK) cell activity as the primary outcome measure. Serum concentrations of cytokines (IL-6, IL-12, IFN-γ, TNF-α) and a questionnaire-based assessment of upper airway infection were the secondary outcomes. At the end of the 8 weeks, NK cell activity significantly improved in the PPCE group compared to the placebo group (p < 0.05). Similarly, the concentrations of IFN-γ and IL-12 significantly increased (p < 0.05). However, there were no significant differences between the two groups in the cytokines IL-6 and TNF-α. Additionally, no adverse effects were observed during the trial. These findings suggest that PPCE supplementation is safe and potentially benefits immune stimulation by enhancing NK cell activity and inducing the production of Th-1 type cell-stimulating cytokines like IL-12 in healthy individuals.

Plasma exosomal miR-150-3p, NMT2, and PRDM1 as predictive biomarkers of acute tumor response in patients with cervical cancer undergoing chemoradiotherapy

Locally advanced cervical cancer (LACC) is primarily treated with weekly cisplatin-based concurrent chemoradiotherapy (CCRT); however, predicting acute tumor response remains challenging. This study aimed to identify plasma exosomal microRNAs (miRNAs) and messenger RNAs (mRNAs) that could predict rapid tumor regression in patients with LACC undergoing CCRT. Overall, 41 patients with stage IB-IVB cervical cancer were included. All patients received CCRT, and plasma exosomal RNA samples were collected before treatment and 2 weeks after radiation therapy (RT). Acute tumor response (AR) was defined as the regression rate of tumor volume (TV) (cm3) measured at the fourth week of treatment compared with the initial TV (iTV). The log2 fold change of miRNA and mRNA was calculated by comparing RNA read counts before and after the second week of CCRT for each patient. A correlation matrix identified RNAs associated with AR. The selected RNAs were validated through linear regression and Wilcoxon rank-sum tests. Leave-one-out cross-validation was performed in subgroups based on iTV. miR-150-3p, NMT2, and PRDM1 were identified as key predictors of AR, demonstrating significant associations with immune-mediated tumor responses. A decrease in post-RT levels of these RNAs was significantly associated with poor AR, particularly in patients with large iTVs. The predictive model combining miR-150-3p, NMT2, and PRDM1 showed strong correlation with AR (R2 = 0.831, P < 0.0001) in the test dataset and was validated in an independent cohort (R2 = 0.496, P = 0.006). Cross-validation indicated the robustness of these biomarkers in predicting AR across varying TVs. These findings highlight the potential of plasma exosomal miR-150-3p, NMT2, and PRDM1 are promising biomarkers for predicting AR in patients with LACC undergoing CCRT. These findings could facilitate personalized RT strategies and improve patient outcomes. Further multicenter studies are warranted to validate these biomarkers in larger, diverse cohorts.

INTASYL self-delivering RNAi decreases TIGIT expression, enhancing NK cell cytotoxicity: a potential application to increase the efficacy of NK adoptive cell therapy against cancer

Natural killer (NK) cells are frontline defenders against cancer and are capable of recognizing and eliminating tumor cells without prior sensitization or antigen presentation. Due to their unique HLA mismatch tolerance, they are ideal for adoptive cell therapy (ACT) because of their ability to minimize graft-versus-host-disease risk. The therapeutic efficacy of NK cells is limited in part by inhibitory immune checkpoint receptors, which are upregulated upon interaction with cancer cells and the tumor microenvironment. Overexpression of inhibitory receptors reduces NK cell-mediated cytotoxicity by impairing the ability of NK cells to secrete effector cytokines and cytotoxic granules. T-cell immunoreceptor with immunoglobulin and ITIM domains (TIGIT), a well-known checkpoint receptor involved in T-cell exhaustion, has recently been implicated in the exhaustion of NK cells. Overcoming TIGIT-mediated inhibition of NK cells may allow for a more potent antitumor response following ACT. Here, we describe a novel approach to TIGIT inhibition using self-delivering RNAi compounds (INTASYL™) that incorporates the features of RNAi and antisense technology. INTASYL compounds demonstrate potent activity and stability, are rapidly and efficiently taken up by cells, and can be easily incorporated into cell product manufacturing. INTASYL PH-804, which targets TIGIT, suppresses TIGIT mRNA and protein expression in NK cells, resulting in increased cytotoxic capacity and enhanced tumor cell killing in vitro. Delivering PH-804 to NK cells before ACT has emerged as a promising strategy to counter TIGIT inhibition, thereby improving the antitumor response. This approach offers the potential for more potent off-the-shelf products for adoptive cell therapy, particularly for hematological malignancies.

Vaccination with O-linked Mannans Protects against Systemic Candidiasis through Innate Lymphocyte Populations

Candida spp. are the fourth leading cause of bloodstream infections in hospitalized patients and the most common cause of invasive fungal infection. No vaccine against Candida spp. or other fungal pathogens of humans is available. We recently discovered the Blastomyces Dectin-2 ligand endoglucanase 2 that harbors antigenic and adjuvant functions and can function as a protective vaccine against that fungus. We also reported that the adjuvant activity, which is mediated by O-mannans decorating the C terminus of Blastomyces Dectin-2 ligand endoglucanase 2, can augment peptide Ag-induced vaccine immunity against heterologous agents, including Cryptococcus, Candida, and influenza. In this article, we report that the O-linked mannans alone, in the absence of any antigenic peptide, can also protect against systemic candidiasis, reducing kidney fungal load and increasing survival in a Dectin-2-dependent manner. We found that this long-term glycan-induced protection is mediated by innate lymphocyte populations including TCR-γδ+ T cells, innate lymphoid cells, and NK cells that subsequently activate and release reactive oxygen species from neutrophils and monocytes. Our findings suggest that Blastomyces O-mannan displayed by Eng2 induces a form of protective trained immunity mediated by innate lymphocyte populations.

Striking a balance: the Goldilocks effect of CD8α expression on NK cells

NK cells are cytotoxic innate immune cells involved in antitumor immunity, and they provide a treatment option for patients with acute myeloid leukemia (AML). In this issue of the JCI, Cubitt et al. investigated the role of CD8α, a coreceptor present on approximately 40% of human NK cells. IL-15 stimulation of CD8α- NK cells induced CD8α expression via the RUNX3 transcription factor, driving formation of a unique induced CD8α (iCD8α+) population. iCD8α+ NK cells displayed higher proliferation, metabolic activity, and antitumor cytotoxic function compared with preexisting CD8α+ and CD8α- subsets. Therefore, CD8α expression can be used to define a potential dynamic spectrum of NK cell expansion and function. Because these cells exhibit enhanced tumor control, they may be used to improve in NK cell therapies for patients with AML.

Beta cells deficient for Renalase counteract autoimmunity by shaping natural killer cell activity

Type 1 diabetes (T1D) arises from autoimmune-mediated destruction of insulin-producing pancreatic beta cells. Recent advancements in the technology of generating pancreatic beta cells from human pluripotent stem cells (SC-beta cells) have facilitated the exploration of cell replacement therapies for treating T1D. However, the persistent threat of autoimmunity poses a significant challenge to the survival of transplanted SC-beta cells. Genetic engineering is a promising approach to enhance immune resistance of beta cells as we previously showed by inactivating the Renalase (Rnls) gene. Here, we demonstrate that Rnls loss of function in beta cells shapes autoimmunity by mediating a regulatory natural killer (NK) cell phenotype important for the induction of tolerogenic antigen-presenting cells. Rnls-deficient beta cells mediate cell-cell contact-independent induction of hallmark anti-inflammatory cytokine Tgfβ1 in NK cells. In addition, surface expression of regulatory NK immune checkpoints CD47 and Ceacam1 is markedly elevated on beta cells deficient for Rnls. Altered glucose metabolism in Rnls mutant beta cells is involved in the upregulation of CD47 surface expression. These findings are crucial to better understand how genetically engineered beta cells shape autoimmunity, giving valuable insights for future therapeutic advancements to treat and cure T1D.

Changes in subset distribution and impaired function of circulating natural killer cells in patients with colorectal cancer

Natural killer (NK) cells are closely associated with malignant tumor progression and metastasis. However, studies on their relevance in colorectal cancer (CRC) are limited. We aimed to comprehensively analyze the absolute counts, phenotypes, and function of circulating NK cells in patients with CRC using multiparametric flow cytometry. The distribution of NK cell subsets in the peripheral circulation of patients with CRC was significantly altered relative to the control group. This is shown by the decreased frequency and absolute count of CD56dimCD16+ NK cells with antitumor effects, contrary to the increased frequency of CD56bright NK and CD56dimCD16- NK cells with poor or ineffective antitumor effects. NK cells in patients with CRC were functionally impaired, with decreased intracellular interferon (IFN)-γ secretion and a significantly lower percentage of cell surface granzyme B and perforin expression. In addition, IFN-γ expression decreased significantly with the tumor stage progression. Based on a comprehensive analysis of the absolute counts, phenotypes, and functional markers of NK cells, we found an altered subset distribution and impaired function of circulating NK cells in patients with CRC.

Lingering Effects of Early Institutional Rearing and Cytomegalovirus Infection on the Natural Killer Cell Repertoire of Adopted Adolescents

Adversity during infancy can affect neurobehavioral development and perturb the maturation of physiological systems. Dysregulated immune and inflammatory responses contribute to many of the later effects on health. Whether normalization can occur following a transition to more nurturing, benevolent conditions is unclear. To assess the potential for recovery, blood samples were obtained from 45 adolescents adopted by supportive families after impoverished infancies in institutional settings (post-institutionalized, PI). Their immune profiles were compared to 39 age-matched controls raised by their biological parents (non-adopted, NA). Leukocytes were immunophenotyped, and this analysis focuses on natural killer (NK) cell populations in circulation. Cytomegalovirus (CMV) seropositivity was evaluated to determine if early infection contributed to the impact of an atypical rearing. Associations with tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ), two cytokines released by activated NK cells, were examined. Compared to the NA controls, PI adolescents had a lower percent of CD56bright NK cells in circulation, higher TNF-α levels, and were more likely to be infected with CMV. PI adolescents who were latent carriers of CMV expressed NKG2C and CD57 surface markers on more NK cells, including CD56dim lineages. The NK cell repertoire revealed lingering immune effects of early rearing while still maintaining an overall integrity and resilience.

Beta Cells Deficient for Renalase Counteract Autoimmunity by Shaping Natural Killer Cell Activity

Type 1 diabetes (T1D) arises from autoimmune-mediated destruction of insulin-producing pancreatic beta cells. Recent advancements in the technology of generating pancreatic beta cells from human pluripotent stem cells (SC-beta cells) have facilitated the exploration of cell replacement therapies for treating T1D. However, the persistent threat of autoimmunity poses a significant challenge to the survival of transplanted SC-beta cells. Genetic engineering is a promising approach to enhance immune resistance of beta cells as we previously showed by inactivating of the Renalase (Rnls) gene. Here we demonstrate that Rnls loss-of-function in beta cells shape autoimmunity by mediating a regulatory Natural Killer (NK) cell phenotype important for the induction of tolerogenic antigen presenting cells. Rnls-deficient beta cells mediate cell-cell-contact-independent induction of hallmark anti-inflammatory cytokine Tgfβ1 in NK cells. In addition, surface expression of key regulatory NK immune checkpoints CD47 and Ceacam1 are markedly elevated on beta cells deficient for Rnls. Enhanced glucose metabolism in Rnls mutant beta cells is responsible for upregulation of CD47 surface expression. These findings are crucial to a better understand how genetically engineered beta cells shape autoimmunity giving valuable insights for future therapeutic advancements to treat and cure T1D.