"M1 macrophage polarization prevails in EBV infected children in an immuneregulatory environment"

Presence of Epstein-Barr virus (EBV) antigens detected by sensitive methods has no influence on local immune environment in diffuse large B cell lymphoma

EBV+ diffuse large B cell lymphoma (DLBCL) not otherwise specified (NOS) is a new entity confirmed by the World Health Organization (WHO) in 2017. In this new entity, the virus may contribute to a tolerogenic microenvironment. Traces of the virus have been described in DLBCL with more sensitive methods, in cases that were originally diagnosed as negative. The aim of this study was to analyze the expression of immune response genes in the tumor microenvironment to disclose the role of the virus and its traces in DLBCL. In 48 DLBCL cases, the expression of immune response genes and the presence of molecules that induce tolerance, such as TIM3, LAG3 and PDL1 by immunohistochemistry (IHC), were studied. To broaden the study of the microenvironment, tumor-associated macrophages (TMAs) were also explored. No significant differences were observed in the expression of immune response genes in the EBV+ DLBCL and those cases that were EBV- DLBCL but that exhibited viral traces, assessed by ViewRNA assay. Only the EBV+ DLBCL cases displayed a significantly higher increase in the expression of CD8 and cytotoxic T cells detected by gene expression analysis, and of PDL1 in tumor cells and in the expression of CD68 in the tumor microenvironment detected by IHC, not observed in those cases with viral traces. The increase in CD8 and cytotoxic T cells, PDL1 and CD68 markers only in EBV+ DLBCL may indicate that traces of viral infection might not have influence in immune response markers.

Tonsillar cytotoxic CD4 T cells are involved in the control of EBV primary infection in children

CD4 T cells play a key role in Epstein Barr virus (EBV) infection, by modulating latent antigen expression, and exhibiting cytotoxic and regulatory properties. Our aim was to evaluate the presence of Granzyme B (GZMB) and Foxp3 CD4 T cells at different EBV infection status and latency profiles. We examined CD4, GZMB, Foxp3, IL10, TGF-β, CD4-GZMB and CD4-Foxp3 expression at the tonsils of pediatric patients with different infective status and EBV latency profiles. CD4+, GZMB+, Foxp3+, CD4-GZMB+ and CD4-Foxp3+ cell counts were higher at the interfollicular region. Higher expression of CD4-GZMB was found in primary infected patients compared to healthy carriers. In patients that expressed latency III antigens, we demonstrated lower CD4+, CD4-GZMB+, CD4-Foxp3+ expression; a negative correlation between the immunoregulatory cytokine IL-10+ and GZMB+ as well as a positive correlation of IL-10+ and CD4+. In patients expressing the lytic protein BMRF1, a positive correlation of TGF-β+ with CD4-GZMB+ and CD4-Foxp3+ was observed. Our findings indicate that CD4-GZMB+ cells are involved in the restriction of primary EBV infection in pediatric patients, which could partially explain the lack of symptoms, whereas both CD4-GZMB+ and CD4-Foxp3+ cells could be involved in the modulation of latency.

Study on the Role and Mechanism of SLC3A2 in Tumor-Associated Macrophage Polarization and Bladder Cancer Cells Growth

Background: Solute carrier family 3 member 2 (SLC3A2) is highly expressed in various types of cancers, including bladder cancer (BLCA). However, the role and mechanism of SLC3A2 in the onset and progression of BLCA are still unclear. Methods: The interfering plasmid for SLC3A2 was constructed and transfected into BLCA cells. Cell proliferation, invasion, and migration abilities were assessed to evaluate the impact of SLC3A2 silencing on BLCA cell growth. M1 and M2 macrophage polarization markers were detected to evaluate macrophage polarization. The levels of reactive oxygen species (ROS), lipid peroxidation, and Fe2+, as well as the expression of ferroptosis-related proteins, were measured to assess the occurrence of ferroptosis. Ferroptosis inhibitors were used to verify the mechanism. Results: The experimental results showed that SLC3A2 was highly expressed in BLCA cell lines. The proliferation, invasion, and migration of BLCA cells were reduced after interfering with SLC3A2. Interference with SLC3A2 led to increase the expression of M1 macrophage markers and decreased the expression of M2 macrophage markers in M0 macrophages co-cultured with tumor cells. Additionally, interference with SLC3A2 led to increased levels of ROS, lipid peroxidation, and Fe2+, downregulated the expression of solute carrier family 7 member11 (SLC7A11) and glutathione peroxidase 4 (GPX4), while upregulated the expression of acyl-coA synthetase long chain family member 4 (ACSL4) and transferrin receptor 1 (TFR1) in BLCA cells. However, the impact of SLC3A2 interference on cell proliferation and macrophage polarization was impeded by ferroptosis inhibitors. Conclusion: Interference with SLC3A2 inhibited the growth of BLCA cells and the polarization of tumor-associated macrophages by promoting ferroptosis in BLCA cells.

Cholinergic Polarization of Human Macrophages

Macrophages serve as vital defenders, protecting the body by exhibiting remarkable cellular adaptability in response to invading pathogens and various stimuli. These cells express nicotinic acetylcholine receptors, with the α7-nAChR being extensively studied due to its involvement in activating the cholinergic anti-inflammatory pathway. Activation of this pathway plays a crucial role in suppressing macrophages' production of proinflammatory cytokines, thus mitigating excessive inflammation and maintaining host homeostasis. Macrophage polarization, which occurs in response to specific pathogens or insults, is a process that has received limited attention concerning the activation of the cholinergic anti-inflammatory pathway and the contributions of the α7-nAChR in this context. This review aims to present evidence highlighting how the cholinergic constituents in macrophages, led by the α7-nAChR, facilitate the polarization of macrophages towards anti-inflammatory phenotypes. Additionally, we explore the influence of viral infections on macrophage inflammatory phenotypes, taking into account cholinergic mechanisms. We also review the current understanding of macrophage polarization in response to these infections. Finally, we provide insights into the relatively unexplored partial duplication of the α7-nAChR, known as dup α7, which is emerging as a significant factor in macrophage polarization and inflammation scenarios.

EBV Impact in Peripheral Macrophages' Polarization Cytokines in Pediatric Patients

Macrophages are exceptionally flexible cells. The presence of inflammatory cytokines such as IFN-γ and TNF-α results in an M1 (CD68) activation, while cytokines such as IL-10 or TGF-β induce the M2 (CD163) activation. Our aim was to study the behavior of peripheral cytokines involved in macrophage polarization and relate them with tissue findings to further comprehend the role of macrophages in EBV pediatric infection. We studied cytokine expression in tonsils and peripheral blood samples of children in different stages of infection. Peripheral cytokines were compared with macrophage polarization markers and viral protein expression in tonsils. Only IL-10 showed a negative correlation between compartments, exclusively in patients undergoing viral reactivation (R). Higher expressions of peripheral IL-1β, IL-23, and IL-12p40 in R children were observed. Lower expressions of local and peripheral TNF-α in patients with broader expressions of latent and lytic viral proteins were demonstrated. In healthy carrier (HC) patients, IL-23 positively correlated with CD163, and IP-10 positively correlated with CD68. Our results indicated that EBV might modulate antigen expression in the presence of TNF-α and influence peripheral cytokine expression differently in each stage of infection. Moreover, peripheral cytokines might have a particular role in macrophage polarization in HC.

ACSL4 promotes ferroptosis and M1 macrophage polarization to regulate the tumorigenesis of nasopharyngeal carcinoma

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a head and neck malignant tumor with a high incidence and recurrence rate. The crosstalk between ferroptosis and tumor-associated macrophages (TAMs) is thought to have major implications in interfering with cancers. We intended to explore the effect of acyl-CoA synthetase long-chain family member 4 (ACSL4) on the pathogenesis of NPC via ferroptosis and TAMs.

METHODS

Differential genes in NPC patients were analyzed using publicly available databases, and the ferroptosis-related gene ACSL4 was identified. Expression of ACSL4 in NPC cell lines and xenografted mice was examined. Colony formation, cell proliferation, migration, and invasion were assessed. The abundance of epithelial-mesenchymal transition (EMT) markers (E-cadherin, N-cadherin, and Vimentin) was confirmed. Lipid peroxidation levels and related markers were measured. Clophosome was administered to determine the role of TAMs in NPC mice.

RESULTS

Low levels of ACSL4 were observed in NPC patients and CNE-2 and 5-8F cells. Erastin (a ferroptosis inducer) and ACSL4 increased lipid peroxidation, decreased cell viability, colony formation, cell proliferation, migration and invasion, and inhibited EMT. Moreover, Erastin and ACSL4 promoted M2 to M1 macrophage polarization. The effects of erastin and ACSL4 were additive. Ferrostatin-1, an inhibitor of ferroptosis, exerted the opposite effect and reversed the beneficial effects of ACSL4 overexpression. In xenograft mice, ACSL4 and clophosome hindered the growth of NPC, and extra clophosome slightly enhanced the antitumor effect of ACSL4.

CONCLUSION

Our findings indicated that ACSL4 inhibited the pathogenesis of NPC, at least through crosstalk between ferroptosis and macrophages, providing potential direction for NPC therapy.

Porcine Reproductive and Respiratory Syndrome Virus Modulates the Switch of Macrophage Polarization from M1 to M2 by Upregulating MoDC-Released sCD83

Porcine reproductive and respiratory syndrome virus (PRRSV), the most economically important infectious disease of pigs, elicits poor innate and adaptive immune responses. Soluble CD83 (sCD83), a secretion from various immune cell populations, especially MoDCs, is involved in negatively regulating the immune response. We speculate sCD83 may be a critical factor in the process of PRRSV-coordinated macrophage polarization. In this study, we found that PAMs co-cultured with PRRSV-infected MoDCs inhibited the M1 macrophage while enhancing the M2 macrophage. This was accompanied by a decrease in the pro-inflammatory cytokine TNF-α and iNOS and an increase in the anti-inflammatory cytokine IL-10 and Arg1. Meanwhile, sCD83 incubation causes the same specific effects lead to a switch in macrophage from M1 to M2. Neutralization of sCD83 removes the inhibitory effects of PRRSV on PAMs. Using reverse genetics, we generated recombinant PRRSVs with mutations in N protein, nsp1α, and nsp10 (knockout sCD83-concerned key amino acid site). Four mutant viruses lost the suppression of M1 macrophage markers, in contrast to the restriction of the upregulation of M2 macrophage markers. These findings suggest that PRRSV modulates the switch of macrophage polarization from M1 to M2 by upregulating the MoDC-induced secretion of CD83, providing new insights into the mechanism by which PRRSV regulates host immunity.

Tumor Molecular and Microenvironment Characteristics in EBV-Associated Malignancies as Potential Therapeutic Targets: Focus on Gastric Cancer

Although most people are infected with Epstein-Barr Virus (EBV) during their lifetime, only a minority of them develop an EBV-associated malignancy. EBV acts in both direct and indirect ways to transform infected cells into tumor cells. There are multiple ways in which the EBV, host, and tumor environment interact to promote malignant transformation. This paper focuses on some of the mechanisms that EBV uses to transform the tumor microenvironment (TME) of EBV-associated gastric cancer (EBVaGC) for its benefit, including overexpression of Indoleamine 2,3-Dioxygenase 1 (IDO1), synergism between H. pylori and EBV co-infection, and M1 to M2 switch. In this review, we expand on different modalities and combinatorial approaches to therapeutically target this mechanism.

PD-L1 is upregulated in CD163+ tonsillar macrophages from children undergoing EBV primary infection

Epstein-Barr Virus (EBV) is a tumor associated virus that modulates not only the infected cells but also innate and adaptive immunity. Macrophages play a key role in tumor development and progression. Particularly, the M2 phenotype (CD163) with anti-inflammatory activity contributes to a favorable microenvironment for tumor development while the M1 (CD68) proinflammatory phenotype contributes to a restrictive one. In the context of pediatric EBV infection, little is known about macrophage contribution to PD-L1 expression, a molecule involved in immune exhaustion. We studied tonsils of primary infected (PI), healthy carriers (HC), reactivated (R), and not infected (NI) pediatric patients. Positive correlations were demonstrated for CD68+PD-L1+ in R and for CD163+PD-L1+ only in PI. Furthermore, CD163+PD-L1+ cell numbers were higher than PD-L1+CD68+ in PI patients. In addition, a positive correlation between PD-L1+CD163+ cells and LMP1 viral latent protein was observed in PI patients, and a positive correlation between PD-L1+CD68+ cells and BMRF1 lytic antigen was demonstrated. A positive correlation between TGF-β and PD-L1 expression was demonstrated in HC patients. Our findings indicate that EBV's lytic and latent antigens might be regulating macrophages' PD-L1 expression, particularly in PI patients, whereas, surprisingly, only TGF-β could be related to total PD-L1 upregulation. Given the relevance of macrophages and the PD-1/PD-L1 pathway in tumor progression and survival, more studies in early EBV infection could help to develop EBV-associated tumor therapies.