Resveratrol is a natural polyphenol derived from plants such as grapes and berries. In addition to its role in plants during injury and infection, various cardioprotective, neuroprotective, and longevity-promoting effects were reported in diverse model organisms. The primary target of resveratrol is the deacetylase Sirtuin 1 (SIRT1), which regulates many immunological processes, including BCG-induced trained immunity response in humans. We, therefore, investigated the effect of resveratrol on trained immunity induced by BCG, β-glucan, C. albicans, or oxidized low-density lipoprotein (oxLDL). Using an in-vitro model of trained immunity with monocytes obtained from healthy donors, we demonstrate that resveratrol amplifies BCG-induced trained immunity regarding IL-6 and TNFα production after a secondary challenge. Although resveratrol did not improve and even limited glycolysis, oxidative phosphorylation, and reactive oxygen species production, it enhanced the permissive epigenetic mark H3K27Ac on IL-6 and TNFα promoters. In contrast to BCG-induced trained immunity, resveratrol potently inhibited training induced by β-glucan, C. albicans, oxLDL, and muramyl dipeptide (MDP), a peptidoglycan component of BCG. Resveratrol's unique boosting effect on BCG training depended on BCG being alive and metabolically active. These results suggest that resveratrol might amplify the effects of BCG vaccination, which should be mechanistically characterized further. In addition, resveratrol could alleviate oxLDL-induced training of innate immune cells in atherosclerosis, and in-vivo studies of trained immunity combined with resveratrol are warranted to explore these therapeutic possibilities.

During sterile inflammation, tissue damage induces excessive activation and infiltration of neutrophils into tissues, where they critically contribute to organ dysfunction. Tight regulation of neutrophil migration and their effector functions is crucial to prevent overshooting immune responses. Neutrophils utilize more glutamine, the most abundant free α-amino acid in the human blood, than other leukocytes. However, under inflammatory conditions, the body's requirements exceed its ability to produce sufficient amounts of glutamine. This study investigates the impact of glutamine on neutrophil recruitment and their key effector functions. Glutamine treatment effectively reduced neutrophil activation by modulating β2-integrin activity and chemotaxis in vitro. In a murine in vivo model of sterile inflammation induced by renal ischemia-reperfusion injury, glutamine administration significantly attenuated neutrophil recruitment into injured kidneys. Transcriptomic analysis revealed, glutamine induces transcriptomic reprogramming in murine neutrophils, thus improving mitochondrial functionality and glutathione metabolism. Further, glutamine influenced key neutrophil effector functions, leading to decreased production of reactive oxygen species and formation of neutrophil extracellular traps. Mechanistically, we used a transglutaminase 2 inhibitor to identify transglutaminase 2 as a downstream mediator of glutamine effects on neutrophils. In conclusion, our findings suggest that glutamine diminishes activation and recruitment of neutrophils and thus identify glutamine as a potent means to curb overshooting neutrophil responses during sterile inflammation.

Tuberculosis (TB) is one of the leading causes of death worldwide and a major public health problem. Immune evasion mechanisms and antibiotic resistance highlight the need to better understand this disease and explore alternative treatment approaches. Mycobacterial infection modulates the macrophage response and metabolism to persist and proliferate inside the cell. Cannabinoid receptor type 2 (CB2) is expressed mainly in leukocytes and modulates the course of inflammatory diseases. Therefore, our study aimed to evaluate the effects of the CB2-selective agonist GP1a on irradiated M. bovis-BCG (iBCG)-induced J774A.1 macrophage activation. We observed increased expression of CB2 in macrophages after iBCG stimulation. The pretreatment with CB2-agonists, GP1a, JWH-133, and GW-833972A (10 µM), reduced iBCG-induced TNF-α and IL-6 release by these cells. Moreover, the CB2-antagonist AM630 (200nM) treatment confirmed the activity of GP1a on CB2 by scale down its effect on cytokine production. GP1a pretreatment (10 µM) also inhibited the iBCG-induced production of inflammatory mediators as prostaglandin (PG)E2 and nitric oxide (NO) by macrophages. Additionally, GP1a pretreatment also reduced the transcription of proinflammatory genes (inos, il1b, cox2) and genes related to lipid metabolism (dgat1, acat1, plin2, atgl, cd36). Indeed, lipid droplet accumulation was reduced by GP1a treatment which was partially blockade by AM630 pretreatment. Finally, GP1a pretreatment reduced the activation of the NF-κB signaling pathway. In conclusion, the activation of CB2 by GP1a modulated the macrophage response to iBCG by reducing inflammatory mediator levels and metabolic reprogramming.

Ectopic lipid accumulation in macrophages is responsible for the formation of macrophage foam cells (MFCs) which are involved in the crosstalk with the perivascular adipose tissue (PVAT) of the vascular wall that plays a pivotal role in the progression of atherosclerosis. However, the interrelationship between MFCs and PVAT implementing adipocyte dysfunction during atherosclerosis has not yet been established. We hypothesized that MFC-secreted mediator(s) is causally linked with PVAT dysfunction and the succession of atherosclerosis. To test this hypothesis, MFCs were cocultured with adipocytes, or the conditional media of MFCs (MFC-CM) were exposed to adipocytes and found a significant induction of fat lipolysis in adipocytes. The molecular filtration followed by the high-performance liquid chromatography (HPLC) fractionation and liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) analysis of MFC-CM revealed a novel mediator fetuin-A (FetA) that significantly augments toll-like receptor 4 (TLR4)-dependent fat lipolysis in adipocytes. Mechanistically, MFC-derived FetA markedly increased TLR4-dependent c-Jun N-terminal kinases (JNK)/extracellular signal-regulated kinases (ERK) activation that causes spontaneous fat lipolysis implementing adipocyte dysfunction. Thus, the present study provides the first evidence of MFC-derived FetA that induces adipocyte dysfunction by the stimulation of spontaneous fat lipolysis. Therefore, targeting the crosstalk between MFCs and adipocytes could be a newer approach to counter the progression of atherosclerosis.

Basic leucine zipper transcription factor ATF-like 2 (BATF2) is a transcription factor that is known to exhibit tumor-suppressive activity in cancer cells. Within recent years, however, BATF2 has also emerged as an important transcriptional regulator of the immune system. Through its immunomodulatory function, BATF2 has been implicated in a variety of (patho)physiological processes, including host defense against infection, anti-tumor immunity, and maintenance of tissue inflammatory homeostasis. Below, we discuss recent literature that has provided insight into the role of BATF2 as a transcriptional regulator of immune responses in health and disease, including the cell types that express BATF2, the different diseases in which the immunomodulatory effects of BATF2 have been shown to play a role, and the molecular mechanisms through which BATF2 is thought to exert those effects. In doing so, we highlight that the immunological effects of BATF2 are highly context-dependent, and we point out overlap between the mechanisms of action of BATF2 in infectious disease and non-infectious disease. We also discuss areas of interest for future research, the clinical relevance of better understanding BATF2 function, and potential strategies for therapeutic modulation of BATF2.

Neutrophils are traditionally viewed as uncomplicated exterminators that arrive quickly at sites of infection, kill pathogens, and then expire. However, recent studies employing modern transcriptomics coupled with novel imaging modalities have discovered that neutrophils exhibit significant heterogeneity within organs and have complex functional roles ranging from tissue homeostasis to cancer and chronic pathologies. This has revised the view that neutrophils are simplistic butchers, and there has been a resurgent interest in neutrophils. The spleen was described as a granulopoietic organ more than 4 decades ago, and studies indicate that neutrophils are briefly retained in the spleen before returning to circulation after proliferation. Transcriptomic studies have discovered that splenic neutrophils are heterogeneous and distinct compared with those in blood. This suggests that a unique hematopoietic niche exists in the splenic microenvironment, i.e., capable of programming neutrophils in the spleen. During severe systemic inflammation with an increased need of neutrophils, the spleen can adapt by producing neutrophils through emergency granulopoiesis. In this review, we describe the structure and microanatomy of the spleen and examine how cells within the splenic microenvironment help to regulate splenic granulopoiesis. A focus is placed on exploring the increase in splenic granulopoiesis to meet host needs during infection and inflammation. Emerging technologies such as single-cell RNA sequencing, which provide valuable insight into splenic neutrophil development and heterogeneity, are also discussed. Finally, we examine how tumors subvert this natural pathway in the spleen to generate granulocytic suppressor cells to promote tumor growth.

Oral mucosal colonization by C. albicans (Ca) is benign in healthy people but progresses to deeper infection known as oropharyngeal candidiasis (OPC) that may become disseminated when combined with immunosuppression. Cortisone use and neutropenia are risk factors for invasive mucosal fungal infections, however the mechanisms are poorly understood. Here we identify in vivo neutrophil functional complexes known as swarms that are crucial for preventing Ca epithelial invasion. Anti-Ly6G antibody treatment impaired swarm formation and increased fungal infection depth confirming the role of neutrophil swarms in limiting Ca invasion. Neutrophil swarm function could be disrupted by administration of resolvins, and required leukotriene B4 receptor 1 (BLT1) expression so that administration of a leukotriene synthesis inhibitor reduced neutrophil swarm size permitting Ca invasion beyond the basement membrane. Cortisone treatment similarly reduced neutrophil swarming behavior and BLT1 expression and delayed expression of epithelial cytokines and chemokines. Thus, swarm structures have an important function in preventing deep invasion by C. albicans within the oral mucosa and represent a mechanism for increased disease severity under immune deficient clinical settings.

Trained immunity induces antigen-agnostic enhancement of host defense and protection against secondary infections, but inappropriate activation can contribute to the pathophysiology of inflammatory diseases. Tight regulation of trained immunity is therefore needed to avoid pathology, but little is known about the endogenous processes that modulate it. Here, we investigated the potential of IL-10, a prototypical anti-inflammatory cytokine, to inhibit trained immunity. IL-10 induced tolerance and inhibited trained immunity in primary human monocytes at both functional and transcriptional levels. Inhibition of STAT3, a signaling route that mediates IL-10 signals, induced trained immunity. IL-10 downregulated glycolytic and oxidative metabolism in monocytes, but did not impact the metabolic effects of β-glucan-induced trained immunity. Furthermore, IL-10 prevented increased ROS production in BCG-induced training, but did not influence phagocytosis upregulation. In a cohort study of healthy volunteers vaccinated with BCG, genetic variants that influenced IL-10 or its receptor modulated BCG-induced trained immunity. Furthermore, circulating IL-10 concentrations were negatively correlated with induction of trained immunity after BCG vaccination in a sex-specific manner. In conclusion, IL-10 inhibited several, albeit not all, immunological functions amplified after induction of trained immunity. Follow-up studies should explore the precise molecular mechanism that mediate the effects of IL-10 on trained immunity. Addressing these knowledge gaps is an important step towards optimizing IL-10's potential as a therapeutic target in diseases characterized by inappropriate induction of trained immunity.

Piezo1 is a mechanosensitive, nonselective Ca2+ channel which is broadly expressed in CD4+ T cells. Using lineage-specific Piezo1 knockout mice (Piezo1cKO), we show that loss of Piezo1 in CD4+ T cells significantly increased IFNγ and IL-17 production in vitro under TH1 and TH17 polarizing conditions, respectively. Despite their intrinsic proinflammatory phenotype, Piezo1cKO T cells are incapable of establishing disease in vivo in three separate adoptive transfer (AT) T cell-mediated inflammatory mouse models, including experimental autoimmune encephalomyelitis, inflammatory bowel disease (IBD), and graft versus-host disease. These phenomena coincided with a decreased effector memory (CD44hiCD62Llo) CD4+ T cell pool derived from donor Piezo1cKO T cells, an observation that is related to intrinsic T-cell fitness, as co-transfer IBD mouse model revealed a deficiency in the CD4+ effector memory population derived only from the naïve Piezo1cKO but not co-infused Piezo1WT CD4+ T cell source. Taken together, our results support Piezo1 as restraining proinflammatory T cell differentiation while contributing to the generation and persistence of the effector memory pool during CD4+ T cell-mediated immunopathology.

Atopic dermatitis (AD) is a complex disease influenced by alterations in the skin microbiome and immune dysregulation. Despite the recognized role of these factors, the specific pathways by which distinct microbial populations affect skin immunity remain insufficiently understood. On a molecular level, the pathogenesis of AD involves critical cytokines such as IL-4, IL-17, interferon-γ (IFN-γ), and IL-10, which contribute to the imbalance in T helper (Th) cell responses. Importantly, gamma-delta (γδ) T cells, which produce these cytokines and infiltrate affected epithelial cells in AD, have been underexplored. This study seeks to alleviate AD symptoms in mice by adjusting both peripheral and local immune environments through the transplantation of skin microbiota. By employing 16S rRNA sequencing, we characterized the skin microbiome of the mouse model. Our results demonstrate that microbiota intervention significantly reduces skin thickening and serum IgE levels in DNFB-induced AD mice. Additionally, changes in skin microbiota modulated immune cell dynamics, restoring the Th1/Th2 balance and leading to clinical improvement. These findings highlight the critical role of skin microbiota in shaping immune responses, positioning microbiota-based therapies as a potential treatment for AD.

Brain metastases (BrM) originating from lung and breast cancer can recruit and activate neutrophils to acquire a tumor-promoting phenotype. It is currently unclear if this phenomenon also occurs in BrM arising from other primary sites. Here, we investigated the effect of tumor cells isolated from melanoma, lung and gastrointestinal (GI) cancer BrM on neutrophil biology and functions. We found that lung and GI, but not melanoma BrM cells produced CXCL8/IL-8, and promoted neutrophil recruitment. Similarly, lung and GI, but not melanoma BrM cells, prolonged the survival of neutrophils, and stimulated them to release MMP9 and CCL4/MIP1β. In situ, lung and GI BrM tissues contained significantly higher numbers of tumor-infiltrating neutrophils compared to melanoma BrM. The levels of neutrophil infiltration significantly correlated with the proliferation index of these tumors. Our findings identify variabilities in the immune microenvironment of BrM with different primary sites, which may ultimately affect their pathophysiology and progression.

Although the SARS-CoV-2 infection has established risk groups, identifying biomarkers for disease outcomes is still crucial to stratify patient risk and enhance clinical management. Optimal efficacy of COVID-19 antiviral medications relies on early administration within the initial five days of symptoms, assisting high-risk patients in avoiding hospitalization and improving survival chances. The complete blood count can be an efficient and affordable option to find biomarkers that predict the COVID-19 prognosis due to infection-induced alterations in various blood parameters. This study aimed to associate hematological parameters with different COVID-19 clinical forms and utilize them as disease outcome predictors. We performed a complete blood count in blood samples from 297 individuals with COVID-19 from Belo Horizonte, Brazil. Statistical analysis, as well as ROC Curves and machine learning Decision Tree algorithms were used to identify correlations, and their accuracy, between blood parameters and disease severity. In the initial four days of infection, traditional hematological COVID-19 alterations, such as lymphopenia, were not yet apparent. However, the monocyte percentage and granulocyte-to-lymphocyte ratio proved to be reliable predictors for hospitalization, even in cases where patients exhibited mild symptoms that later progressed to hospitalization. Thus, our findings demonstrate that COVID-19 patients with monocyte percentages lower than 7.7% and a granulocyte-to-lymphocyte ratio higher than 8.75 are assigned to the hospitalized group with a precision of 86%. This suggests that these variables can serve as important biomarkers in predicting disease outcomes and could be used to differentiate patients at hospital admission for managing therapeutic interventions, including early antiviral administration. Moreover, they are simple parameters that can be useful in minimally equipped health care units.

Rheumatoid arthritis is a common autoimmune disease, but little is known about the characteristics of the B cell repertoires in the peripheral blood. In this study, the peripheral IgM repertoires of early rheumatoid arthritis (ERA) patients were analyzed by high-throughput sequencing and bioinformatics analyses. Clonal expansion was observed in IgM repertoires of ERA patients. Interestingly, a subset of the dominant clones in ERA repertoires showed self- and poly-reactivity to several autoantigens. The clones were also present in IgM repertoires of healthy adults but they were not expanded, suggesting that may stem from the natural auto-reactive B cell repertoire. Additionally, the ERA repertoires exhibited a greater extent of somatic hypermutations, particularly in the ERA dominant clones, resulting in an enrichment of amino acids important for antigen-antibody interaction. The in-depth analysis of B-cell repertoires improved our knowledge of the IgM repertoires in early rheumatoid arthritis, offering potential insights into the disease's pathogenesis.

The impact of aging on T cell subsets, specifically CD4+ and CD8+ T cells, leading to immune system dysfunction, has been the focus of scientific investigation due to its potential to reverse age-associated deterioration. Transcriptomic and epigenomic studies have identified the primary regulators in T cell aging. However, comprehending the underlying dynamic mechanisms requires studying these proteins with their interactors. Here, we integrated single-cell RNA sequencing data of naive CD4+ and CD8+ T cells obtained from three different age groups with protein-protein and domain-domain interaction networks to predict and compare the transcriptional protein complexes and identify their capacity to explain age-associated variances. Our novel approach revealed significant effects of aging on the repertoire of complexes, which remains unchanged in naive CD4+ T cells, while in naive CD8+ T cells, it diminishes. In both cell types, there was major deregulation of complexes with the same composition, involving a range of transcription factors. This aging-associated deregulation is characterized by a specific set of protein complexes in naive CD4+ T cells, but this pattern is not observed in naive CD8+ T cells. SMAD3 and BCL11A complexes emerge as key markers in defining a trajectory in aging naive CD4+ T cells. These complexes can accurately distinguish between three different age groups, indicating their potential as targets. The direct link between SMAD3 and FOS complexes whose regulatory role has been previously implicated in aging and MBD3 as the novel key link between SMAD3 and BCL11A complexes implicate a coordinated mechanism in age-associated deregulation.

The role of MIR654 in Burkitt's lymphoma (BL) and whether it impacts expression of MYC, and its downstream activated MIR9 is not known. Expression of MYC, MYCN, MYCL, MIR9/3P, MIR654/5P, and MIR654/3P were assessed by qRT-PCR in biopsy samples from Epstein-Barr virus (EBV)- and EBV+ BL patients and BL cell lines. Effects of modulation of MIR9/3P and MIR654/3P on cell proliferation, apoptosis and chemosensitivity were evaluated. Luciferase reporter assay was performed to validate putative target of MIR654/5P. Effects of MIR9/3P and MIR654/3P on tumor burden and disease outcome were evaluated using xenograft model of BL. Expression of MYC, MYCN, and MIR9/3P was higher in all BL patient samples and cell lines. Expression of MIR654/3P was downregulated in EBV- BL patient samples and cell lines compared to either noncancer lymphoid reactive hyperplasia (LRH) or EBV+ samples and cell lines. Additionally, MIR654/3P overexpression inhibited cell proliferation, induced apoptosis, and increased chemosensitivity in EBV- BL cell lines. Luciferase reporter assay confirmed that MYC is a target of MIR654/3P in both EBV- and EBV+ BL cell lines; however, the effect of MIR654/3P-mediated targeting of MYC is overridden in EBV+ cells. Administration of MIR654/3P mimic or MIR9/3P antagomir in the xenograft model decreased tumor burden and increased survival. Combined intervention with MIR654/3P mimic and MIR9/3P antagomir had synergistic action on decreasing tumor burden and improving disease outcome. MIR654/3P, as a putative tumor suppressor in EBV- BL, collaborated MIR9/3P might serve as a therapeutic agent to treat EBV- BL patients in combination with existing chemotherapy and immunotherapy regimes.

Blood and airway eosinophilia represent markers for the endotype-driven treatment of allergic asthma. Little is known on mechanisms that link eosinophils and airway epithelial cells before and after these cells are infiltrated by eosinophils during allergic response. Given that innate immune mechanisms, mainly mediated by epithelial-derived cytokines (IL-33, IL-25, TSLP), induce eosinophil-maturing/attractive substances, we thought to evaluate the crosstalk between eosinophils and airway epithelial cells in the context of IL-33-mediated allergic inflammation. DUOX1 was previously described in clinically relevant aspects of allergic inflammation in a HDM -induced allergic asthma mice model, and in patients with chronic sinusitis or allergic asthma. Thus, we evaluated the involvement of HDM and eosinophils in the regulation of DUOX1 in airway epithelial cells. To recapitulate the lung environment present at the allergen challenge time in acute asthma, we set up an in vitro model based on murine bone marrow-derived eosinophils differentiated with IL-5 and then activated with IL-33 (EOs33) and TC1 or C57 airway epithelial cells. We found that treatment of epithelial cells with HDM induced an eosinophil-attractive environment and increased DUOX1 expression. Importantly, we found that the co-culture of airway epithelial cells with EOs33 or with conditioned medium from EOs33 enhanced the expression of DUOX1, which was further increased by combined stimulation (HDM plus EOs33). Our results suggest that lung recruited EOs once activated by IL-33 could be involved in a crosstalk loop with airway epithelial cells by DUOX1-mediated IL-33 secretion.

Natural Killer (NK) cells are critical innate immune cells involved in the clearance of virally infected and malignant cells. Human NK cells are distinguished by their surface expression of CD56 and a lack of CD3. While CD56 expression and cell surface density has long been used as the prototypic marker to characterize primary human NK cell functional subsets, the exact functional role of CD56 in primary human NK cells is still not fully understood. Here we eliminated the expression of CD56 in human ex vivo expanded NK cells (CD56bright) using CRISPR/Cas9 in order to assess the function of CD56 in this highly activated and cytotoxic NK cell population. We show that the expression of CD56 has no effect on NK cell proliferative capacity or expression of various activation and inhibitory markers. Further, CD56 does not contribute to NK cell-mediated cytotoxicity, inflammatory cytokine production, or the ability of NK cells to control tumor engraftment in vivo. We also found that while deletion of CD56 did not impact NK cell glycolytic metabolism it did increase NK cell reliance on oxidative phosphorylation. Lastly, CD56 does not alter expanded NK cell in vivo tissue trafficking. Our results indicate that while CD56 expression could be used to indicate a hyper-functional state of NK cells, it does not directly influence the anti-tumor functions of expanded NK cells.

Neutrophil extracellular traps (NETs) are promising promoters in venous thromboembolism (VTE). In the present study, we have investigated the potential thrombogenic role of NETs in colorectal cancer (CRC). A total of 583 patients with gastrointestinal malignancies who were diagnosed with or without VTE by extremities arteriovenous ultrasound and computed tomography were enrolled. The incidence of VTE in CRC was as high as 17.53%. In serological ELISA experiments, Cit-H3, MPO and cfDNA were significantly overexpressed in CRC patients with VTE compared to CRC patients without VTE and healthy individuals. Neutrophils from CRC patients with VTE produced appreciable amounts of NETs after stimulation with phorbol-12-myristate-13-acetate, which were lacking in CRC patients without VTE and healthy individuals. CfDNA was positively correlated with plasmin-α2-antiplasmin complex and tissue plasmin activator inhibitor-1 complex, and Cit-H3 was positively correlated with plasmin-α2-antiplasmin complex, suggesting that NETs are associated with increased fibrinolytic activity. We screened some NETs-related genes by analysing several high-throughput sequencing datasets of VTE and NETs. FCGR1A was identified as the optimal target gene by pan-cancer expression analysis and survival analysis. FCGR1A was significantly overexpressed in the peripheral blood of CRC patients without VTE compared to healthy individuals and showed a positive correlation with cfDNA. Neutrophil-derived NETs were significantly reduced by FCGR1A inhibitor exposure. These findings indicate that NETs are actively involved in VTE in CRC. NETs are promising thrombotic marker and therapeutic target in CRC to prevent the thrombotic consequences of cancer.