Journal of Leukocyte Biology最新文献

{"title":"The peripheral neuroimmune system.","authors":"Keaton Song, Brian S Kim","doi":"10.1093/jleuko/qiae230","DOIUrl":"10.1093/jleuko/qiae230","url":null,"abstract":"<p><p>Historically, the nervous and immune systems were studied as separate entities. The nervous system relays signals between the body and the brain by processing sensory inputs and executing motor outputs, whereas the immune system provides protection against injury and infection through inflammation. However, recent developments have demonstrated that these systems mount tightly integrated responses. In particular, the peripheral nervous system acts in concert with the immune system to control reflexes that maintain and restore homeostasis. Notwithstanding their homeostatic mechanisms, dysregulation of these neuroimmune interactions may underlie various pathological conditions. Understanding how these two distinct systems communicate is an emerging field of peripheral neuroimmunology that promises to reveal new insights into tissue physiology and identify novel targets to treat disease.</p>","PeriodicalId":16186,"journal":{"name":"Journal of Leukocyte Biology","volume":" ","pages":"1291-1300"},"PeriodicalIF":3.6,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11599120/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142467624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rapid progression of CD8 and CD4 T cells to cellular exhaustion and senescence during SARS-CoV2 infection.","authors":"Rodrigo Balsinha Pedroso, Lícia Torres, Lucas Araújo Ventura, Giovanna Caliman Camatta, Catarina Mota, Ana Catarina Mendes, Filipa Ribeiro, Henrique Cerqueira Guimarães, Rafael Calvão Barbuto, Felipe Caixeta, Leandro Souza Nascimento, Mariana Almeida Oliveira, Vinícius Dantas Martins, Gabriela Silveira-Nunes, Unaí Tupinambás, Andrea Teixeira-Carvalho, Luis Graça, Ana Maria Caetano Faria","doi":"10.1093/jleuko/qiae180","DOIUrl":"10.1093/jleuko/qiae180","url":null,"abstract":"<p><p>Risk factors for the development of severe COVID-19 include several comorbidities, but age was the most striking one since elderly people were disproportionately affected by SARS-CoV-2 infection. Among the reasons for this markedly unfavorable response in the elderly, immunosenescence and inflammaging appear as major drivers of this outcome. A finding that was also notable was that hospitalized patients with severe COVID-19 have an accumulation of senescent T cells, suggesting that immunosenescence may be aggravated by SARS-CoV-2 infection. The present work was designed to examine whether these immunosenescence changes are characteristic of COVID-19 and whether it is dependent on disease severity using cross-sectional and longitudinal studies. Our cross-sectional data show that COVID-19, but not other respiratory infections, rapidly increased cellular senescence and exhaustion in CD4 and CD8 T cells during early infection. In addition, longitudinal analyses with patients from Brazil and Portugal provided evidence of increased frequencies of senescent and exhausted T cells over a 7-d period in patients with mild/moderate and severe COVID-19. Altogether, the study suggests that accelerated immunosenescence in CD4 and especially CD8 T-cell compartments may represent a common and unique outcome of SARS-CoV2 infection.</p>","PeriodicalId":16186,"journal":{"name":"Journal of Leukocyte Biology","volume":" ","pages":"1385-1397"},"PeriodicalIF":3.6,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142289255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Obesity alters the macrophages' response to Leishmania major in C57BL/6 mice.","authors":"Vinicius Dantas Martins, Leonardo Vaz, Sara Candida Barbosa, Pierre Henrique de Menezes Paixão, Licia Torres, Marcos Felipe Andrade de Oliveira, Mariana de Almeida Oliveira, Leda Quercia Vieira, Ana Maria Caetano de Faria, Tatiani Uceli Maioli","doi":"10.1093/jleuko/qiae171","DOIUrl":"10.1093/jleuko/qiae171","url":null,"abstract":"<p><p>Obesity is a global pandemic associated with several comorbidities, such as cardiovascular diseases and type 2 diabetes. It is also a predisposing factor for infectious diseases, increasing mortality rates. Moreover, diet-induced obesity can cause metabolic fluctuations that affect macrophage differentiation in various organs. In this sense, we investigated how bone marrow-derived macrophages and tissue-resident macrophages in the skin, which have been differentiated in a host with metabolic syndrome and with previous inflammatory burden, respond to Leishmania major infection. Our findings suggest that bone marrow-derived macrophages from obese C57BL/6 mice, even when cultivated in vitro with inflammatory stimuli, are more susceptible to L. major. These macrophages produce less tumor necrosing factor (TNF) and nitric oxide (NO) and show higher arginase activity. Furthermore, obese mice infected with an intermediate dose of L. major in the skin had more severe lesions when analyzed for ulceration, diameter, thickness, and parasite burden. The increase in lesion severity in obese mice was associated with a higher frequency of tissue-resident macrophages, which are less efficient in killing parasites. We also used CCR2-/- mice, which predominantly have tissue-resident macrophages, and found that lesion resolution was delayed in association with CCR2 deficiency. Additionally, obesity potentiated tissue damage, resulting in higher frequency of tissue-resident macrophages. Our results demonstrate that obesity can alter macrophage responses to infection, leading to increased susceptibility to L. major and more severe cutaneous leishmaniasis. These findings may have important implications for managing obesity-related infections and the development of new therapies for cutaneous leishmaniasis.</p>","PeriodicalId":16186,"journal":{"name":"Journal of Leukocyte Biology","volume":" ","pages":"1372-1384"},"PeriodicalIF":3.6,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142108192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Brain-immune interactions: implication for cognitive impairments in Alzheimer's disease and autoimmune disorders.","authors":"Rashmi Kadam, Muskan Gupta, Orly Lazarov, Bellur S Prabhakar","doi":"10.1093/jleuko/qiae134","DOIUrl":"10.1093/jleuko/qiae134","url":null,"abstract":"<p><p>Progressive memory loss and cognitive dysfunction, encompassing deficits in learning, memory, problem solving, spatial reasoning, and verbal expression, are characteristics of Alzheimer's disease and related dementia. A wealth of studies has described multiple roles of the immune system in the development or exacerbation of dementia. Individuals with autoimmune disorders can also develop cognitive dysfunction, a phenomenon termed \"autoimmune dementia.\" Together, these findings underscore the pivotal role of the neuroimmune axis in both Alzheimer's disease and related dementia and autoimmune dementia. The dynamic interplay between adaptive and innate immunity, both in and outside the brain, significantly affects the etiology and progression of these conditions. Multidisciplinary research shows that cognitive dysfunction arises from a bidirectional relationship between the nervous and immune systems, though the specific mechanisms that drive cognitive impairments are not fully understood. Intriguingly, this reciprocal regulation occurs at multiple levels, where neuronal signals can modulate immune responses, and immune system-related processes can influence neuronal viability and function. In this review, we consider the implications of autoimmune responses in various autoimmune disorders and Alzheimer's disease and explore their effects on brain function. We also discuss the diverse cellular and molecular crosstalk between the brain and the immune system, as they may shed light on potential triggers of peripheral inflammation, their effect on the integrity of the blood-brain barrier, and brain function. Additionally, we assess challenges and possibilities associated with developing immune-based therapies for the treatment of cognitive decline.</p>","PeriodicalId":16186,"journal":{"name":"Journal of Leukocyte Biology","volume":" ","pages":"1269-1290"},"PeriodicalIF":3.6,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141310903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"EP2/EP4 targeting prevents tumor-derived PGE2-mediated immunosuppression in cDC2s.","authors":"Jorge Cuenca-Escalona, Johanna Bödder, Beatriz Subtil, Marta Sánchez-Sánchez, Marcos Vidal-Manrique, Mark W D Sweep, Jonathan A Fauerbach, Alessandra Cambi, Georgina Flórez-Grau, Jolanda M de Vries","doi":"10.1093/jleuko/qiae164","DOIUrl":"10.1093/jleuko/qiae164","url":null,"abstract":"<p><p>Tumor-derived prostaglandin E2 (PGE2) impairs antitumor immunity by priming suppressive functions on various immune cell types, including dendritic cells (DCs). In this way, tumors mediate DC dysfunction and hamper their antitumoral activity. PGE2 is known to modulate DC function via signaling through the E-type prostanoid receptor 2 (EP2) and EP4. Preclinical studies have demonstrated the therapeutic value of targeting EP2/4 receptor signaling in DCs. Ongoing phase 1 clinical trials with EP antagonists have shown immunomodulation in cancer patients. However, the systemic drug administration leads to off-target events and subsequent side effects. To limit the off-target effects of EP targeting, EP2 and EP4 antagonists were encapsulated in polymeric nanoparticles (NPs). In this study, we evaluated the efficacy of EP2/4-specific antagonists encapsulated in NPs to protect conventional type 2 DCs (cDC2s) from suppressive effects of tumor-derived PGE2 in different tumor models. We show that tumor-derived PGE2 signals via EP2/4 to mediate the acquisition of a suppressive phenotype of cDC2s. EP2/4 antagonists encapsulated in NPs impaired the conversion of cDC2s toward a suppressive state and inhibited the occurrence of suppressive features such as interleukin-10 production or the ability to expand regulatory T cells. Importantly, the NPs abolished the transition toward this suppressive state in different tumor models: melanoma-conditioned media, ascites fluid derived from ovarian cancer patients (2-dimensional), and upon coculture with colorectal cancer patient-derived organoids (3-dimensional). We propose that targeting the PGE2-EP2/4 axis using NPs can achieve immunomodulation in the immune system of cancer patients, alleviate tumor-derived suppression, and thus facilitate the development of potent antitumor immunity in cancer patients.</p>","PeriodicalId":16186,"journal":{"name":"Journal of Leukocyte Biology","volume":" ","pages":"1554-1567"},"PeriodicalIF":3.6,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141748428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Signaling by neutrophil G protein-coupled receptors that regulate the release of superoxide anions.","authors":"Claes Dahlgren, Huamei Forsman, Martina Sundqvist, Lena Björkman, Jonas Mårtensson","doi":"10.1093/jleuko/qiae165","DOIUrl":"10.1093/jleuko/qiae165","url":null,"abstract":"<p><p>In human peripheral blood, the neutrophil granulocytes (neutrophils) are the most abundant white blood cells. These professional phagocytes are rapidly recruited from the bloodstream to inflamed tissues by chemotactic factors that signal danger. Neutrophils, which express many receptors that are members of the large family of G protein-coupled receptors (GPCRs), are critical for the elimination of pathogens and inflammatory insults, as well as for the resolution of inflammation leading to tissue repair. Danger signaling molecular patterns such as the N-formylated peptides that are formed during bacterial and mitochondrial protein synthesis and recognized by formyl peptide receptors (FPRs) and free fatty acids recognized by free fatty acid receptors (FFARs) regulate neutrophil functions. Short peptides and short-chain fatty acids activate FPR1 and FFA2R, respectively, while longer peptides and fatty acids activate FPR2 and GPR84, respectively. The activation profiles of these receptors include the release of reactive oxygen species (ROS) generated by the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. Activation of the oxidase and the production of ROS are processes that are regulated by proinflammatory mediators, including tumor necrosis factor α and granulocyte/macrophage colony-stimulating factor. The receptors have signaling and functional similarities, although there are also important differences, not only between the two closely related neutrophil FPRs, but also between the FPRs and the FFARs. In neutrophils, these receptors never walk alone, and additional mechanistic insights into the regulation of the GPCRs and the novel regulatory mechanisms underlying the activation of NADPH oxidase advance our understanding of the role of receptor transactivation in the regulation of inflammatory reactions.</p>","PeriodicalId":16186,"journal":{"name":"Journal of Leukocyte Biology","volume":" ","pages":"1334-1351"},"PeriodicalIF":3.6,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141759194","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In response to bacteria, neutrophils release extracellular vesicles capable of initiating thrombin generation through DNA-dependent and independent pathways.","authors":"Kaitlyn M Whitefoot-Keliin, Chase C Benaske, Edwina R Allen, Mariana T Guerrero, Justin W Grapentine, Benjamin D Schiff, Andrew R Mahon, Mallary C Greenlee-Wacker","doi":"10.1093/jleuko/qiae125","DOIUrl":"10.1093/jleuko/qiae125","url":null,"abstract":"<p><p>Neutrophils release extracellular vesicles, and some subsets of neutrophil-derived extracellular vesicles are procoagulant. In response to Staphylococcus aureus, neutrophils produce extracellular vesicles that associate electrostatically with neutrophil extracellular traps. DNA in neutrophil extracellular traps is procoagulant, but whether neutrophil extracellular vesicles produced during bacterial challenge have similar activity is unknown. Given that extracellular vesicle activity is agonist and cell-type dependent and coagulation contributes to sepsis, we hypothesized that sepsis-causing bacteria increase production of neutrophil-derived extracellular vesicles, as well as extracellular vesicle-associated DNA, and intact extracellular vesicles and DNA cause coagulation. We recovered extracellular vesicles from neutrophils challenged with S. aureus, Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa and measured associated DNA and procoagulant activity. Extracellular vesicles from S. aureus-challenged neutrophils, which were previously characterized, displayed dose-dependent procoagulant activity as measured by thrombin generation in platelet-poor plasma. Extracellular vesicle lysis and DNase treatment reduced thrombin generation by 90% and 37%, respectively. S. epidermidis, E. coli, and P. aeruginosa also increased extracellular vesicle production and extracellular vesicle-associated extracellular DNA, and these extracellular vesicles were also procoagulant. Compared to spontaneously released extracellular vesicles, which demonstrated some ability to amplify factor XII-dependent coagulation in the presence of an activator, only extracellular vesicles produced in response to bacteria could initiate the pathway. S. aureus and S. epidermidis extracellular vesicles had more surface-associated DNA than E. coli and P. aeruginosa extracellular vesicles, and S. aureus and S. epidermidis extracellular vesicles contributed to initiation and amplification of thrombin generation in a DNA-dependent manner. However, DNA on E. coli or P. aeruginosa extracellular vesicles played no role, suggesting that neutrophils release procoagulant extracellular vesicles, which can activate the coagulation cascade through both DNA-dependent and independent mechanisms.</p>","PeriodicalId":16186,"journal":{"name":"Journal of Leukocyte Biology","volume":" ","pages":"1223-1236"},"PeriodicalIF":3.6,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11599124/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141175614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"MT1E in AML: a gateway to understanding regulatory cell death and immunotherapeutic responses.","authors":"Xin Zhuang, Peng Chen, Kaiqian Yang, Rong Yang, Xiaoying Man, Ruochen Wang, Yifen Shi","doi":"10.1093/jleuko/qiae151","DOIUrl":"10.1093/jleuko/qiae151","url":null,"abstract":"<p><p>Regulated cell death (RCD) plays a crucial role in the initiation and progression of tumors, particularly in acute myeloid leukemia (AML). This study investigates the prognostic importance of RCD-related genes in AML and their correlation with immune infiltration. We combined TCGA and GTEx data, analyzing 1,488 RCD-related genes, to develop a predictive model using LASSO regression and survival analysis. The model's accuracy was validated against multiple databases, examining immune cell infiltration, therapy responses, and drug sensitivity among risk groups. RT-qPCR confirmed MT1E expression in AML patients and healthy bone marrow. CCK8 and Transwell assays measured cell proliferation, adhesion, migration, and invasion, while flow cytometry and Western blotting assessed apoptosis and protein expression. We developed a prognostic model using 10 RCD methods, which demonstrated strong predictive ability, showing an inverse correlation between age and risk scores with survival in AML patients. Functional enrichment analysis of the model is linked to immune modulation pathways. RT-qPCR revealed significantly lower MT1E expression in AML vs healthy bone marrow (P < 0.05). Consequently, experiments were designed to assess the function of MT1E overexpression. Findings indicated that MT1E overexpression showed it significantly reduced THP-1 cell proliferation and adhesion (P < 0.001), decreased migration (P < 0.001), and invasiveness (P < 0.05), and increased apoptosis (P < 0.05), with a notable rise in Caspase3 expression. A novel AML RCD risk model was developed, showing promise as a prognostic marker for evaluating outcomes and immune therapy effectiveness. Insights into MT1E's impact on AML cell proliferation and apoptosis open possibilities for improving patient outcomes and devising personalized treatment strategies.</p>","PeriodicalId":16186,"journal":{"name":"Journal of Leukocyte Biology","volume":" ","pages":"1515-1529"},"PeriodicalIF":3.6,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11599122/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141468630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Escherichia coli TolC efflux pump protein is immunogenic and elicits protective antibodies.","authors":"Thaynara O Silva, Bárbara A Teixeira, Leon V S Costa, Luiza S Barbosa, Lucas C do Nascimento, João G C Fanticelli, Caroline Rotilho, Rafael V C Branco, Lucas S Silva, Maria E Ferreira, Thais L Costa, Sanderson V Monteiro, Juliana Dos Santos Abreu, Bia F Rajsfus, Ana Carolina S Bulla, Jordanna Carneiro, Diego Allonso, Diamantino R Salgado, Juliana Echevarria-Lima, Manuela Leal da Silva, Lilian O Moreira, Priscilla C Olsen","doi":"10.1093/jleuko/qiae201","DOIUrl":"10.1093/jleuko/qiae201","url":null,"abstract":"<p><p>Antimicrobial resistance is an increasing worldwide public health burden that threatens to make existent antimicrobials obsolete. An important mechanism of antimicrobial resistance is the overexpression of efflux pumps, which reduce the intracellular concentration of antimicrobials. TolC is the outer membrane protein of an efflux pump that has gained attention as a therapeutic target. Little is known about the immune response against TolC. Here, we evaluated the immune response against TolC from Escherichia coli. TolC in silico epitope prediction showed several residues that could bind to human antibodies, and we showed that human plasma presented higher titers of anti-TolC IgG and IgA, than IgM. E. coli recombinant TolC protein stimulated macrophages in vitro to produce nitric oxide, as well as interleukin-6 and tumor necrosis factor α, assessed by Griess assay and enzyme-linked immunosorbent assay, respectively. Immunization of mice with TolC intraperitoneally and an in vitro restimulation led to increased T cell proliferation and interferon γ production, evaluated by flow cytometry and enzyme-linked immunosorbent assay, respectively. TolC mouse immunization stimulated anti-TolC IgM and IgG production, with higher levels of IgG1 and IgG2, among the IgG subclasses. Anti-TolC murine antibodies could bind to live E. coli and increase bacterial uptake and elimination by macrophages in vitro. Intraperitoneal or intranasal, but not oral, immunizations with inactivated E. coli also led to anti-TolC antibody production. Finally, TolC immunization increased mouse survival rates to antimicrobial-sensitive or resistant E. coli infection. Our results showed that TolC is immunogenic, leading to the production of protective antibodies against E. coli, reinforcing its value as a therapeutic target.</p>","PeriodicalId":16186,"journal":{"name":"Journal of Leukocyte Biology","volume":" ","pages":"1398-1411"},"PeriodicalIF":3.6,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142289256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"RhoGDI in RBL-2H3 cells acts as a negative regulator of Rho GTPase signaling to inhibit granule exocytosis.","authors":"Eric L Zhang, Jennifer Van Petten, Gary Eitzen","doi":"10.1093/jleuko/qiae150","DOIUrl":"10.1093/jleuko/qiae150","url":null,"abstract":"<p><p>Mast cells are hematopoietic-derived immune cells that possess numerous cytoplasmic granules containing immune mediators such as cytokines and histamine. Antigen stimulation triggers mast cell granule exocytosis, releasing granule contents in a process known as degranulation. We have shown that Rho GTPase signaling is an essential component of granule exocytosis, however, the proteins that regulate Rho GTPases during this process are not well defined. Here we examined the role of Rho guanine-nucleotide dissociation inhibitors (RhoGDIs) in regulating Rho GTPase signaling using RBL-2H3 cells as a mast cell model. We found that RBL-2H3 cells express two RhoGDI isoforms which are primarily localized to the cytosol. Knockdown of RhoGDI1 and RhoGDI2 greatly reduced the levels of all Rho GTPases tested: RhoA, RhoG, Rac1, Rac2, and Cdc42. The reduction in Rho GTPase levels was accompanied by an increase in their membrane-localized fraction and an elevation in the levels of active Rho GTPases. All RhoGDI knockdown strains had altered resting cell morphology, although each strain was activation competent when stimulated. Live cell imaging revealed that the RhoGDI1/2 double knockdown (DKD) strain maintained its activated state for prolonged periods of time compared to the other strains. Only the RhoGDI1/2 DKD strain showed a significant increase in granule exocytosis. Conversely, RhoGDI overexpression in RBL-2H3 cells did not noticeably affect Rho GTPases or degranulation. Based on these results, RhoGDIs act as negative regulators of Rho GTPases during mast cell degranulation, and inhibit exocytosis by sequestering Rho GTPases in the cytosol.</p>","PeriodicalId":16186,"journal":{"name":"Journal of Leukocyte Biology","volume":" ","pages":"1498-1514"},"PeriodicalIF":3.6,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11599123/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141468631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}