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IgG molecules are crucial for the human immune response against bacterial infections. IgGs can trigger phagocytosis by innate immune cells, like neutrophils. To do so, IgGs should bind to the bacterial surface via their variable Fab regions and interact with Fcγ receptors and complement C1 via the constant Fc domain. C1 binding to IgG-labeled bacteria activates the complement cascade, which results in bacterial decoration with C3-derived molecules that are recognized by complement receptors on neutrophils. Next to FcγRs and complement receptors on the membrane, neutrophils also express the intracellular neonatal Fc receptor (FcRn). We previously reported that staphylococcal protein A (SpA), a key immune-evasion protein of Staphylococcus aureus, potently blocks IgG-mediated complement activation and killing of S. aureus by interfering with IgG hexamer formation. SpA is also known to block IgG-mediated phagocytosis in absence of complement, but the mechanism behind it remains unclear. In this study, we demonstrate that SpA blocks IgG-mediated phagocytosis and killing of S. aureus and that it inhibits the interaction of IgGs with FcγRs (FcγRIIa and FcγRIIIb, but not FcγRI) and FcRn. Furthermore, our data show that multiple SpA domains are needed to effectively block IgG1-mediated phagocytosis. This provides a rationale for the fact that SpA from S. aureus contains four to five repeats. Taken together, our study elucidates the molecular mechanism by which SpA blocks IgG-mediated phagocytosis and supports the idea that in addition to FcγRs, the intracellular FcRn is also prevented from binding IgG by SpA.
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Imunoglobulina G , Fagocitose , Receptores de IgG , Proteína Estafilocócica A , Staphylococcus aureus , Complemento C1 , Humanos , Imunoglobulina G/imunologia , Receptores de Complemento , Receptores de IgG/metabolismo , Proteína Estafilocócica A/metabolismoRESUMO
Immunoglobulin (Ig) G molecules are essential players in the human immune response against bacterial infections. An important effector of IgG-dependent immunity is the induction of complement activation, a reaction that triggers a variety of responses that help kill bacteria. Antibody-dependent complement activation is promoted by the organization of target-bound IgGs into hexamers that are held together via noncovalent Fc-Fc interactions. Here we show that staphylococcal protein A (SpA), an important virulence factor and vaccine candidate of Staphylococcus aureus, effectively blocks IgG hexamerization and subsequent complement activation. Using native mass spectrometry and high-speed atomic force microscopy, we demonstrate that SpA blocks IgG hexamerization through competitive binding to the Fc-Fc interaction interface on IgG monomers. In concordance, we show that SpA interferes with the formation of (IgG)6:C1q complexes and prevents downstream complement activation on the surface of S. aureus. Finally, we demonstrate that IgG3 antibodies against S. aureus can potently induce complement activation and opsonophagocytic killing even in the presence of SpA. Together, our findings identify SpA as an immune evasion protein that specifically blocks IgG hexamerization.
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Ativação do Complemento , Fragmentos Fc das Imunoglobulinas/metabolismo , Imunoglobulina G/metabolismo , Multimerização Proteica , Proteína Estafilocócica A/metabolismo , Sítios de Ligação , Células Cultivadas , Humanos , Fagócitos/imunologia , Fagocitose , Ligação Proteica , Staphylococcus aureus/imunologiaRESUMO
The use of human organotypic models for biomedical research is experiencing a significant increase due to their biological relevance, the possibility to perform high-throughput analyses, and their cost efficiency. In the field of anti-infective research, comprising the search for novel antipathogenic treatments including vaccines, efforts have been made to reduce the use of animal models. That is due to two main reasons: unreliability of data obtained with animal models and the increasing willingness to reduce the use of animals in research for ethical reasons. Human three-dimensional (3-D) models may substitute and/or complement in vivo studies, to increase the translational value of preclinical data. Here, we provide an overview of recent studies utilizing human organotypic models, resembling features of the cervix, intestine, lungs, brain, and skin in the context of anti-infective research. Furthermore, we focus on the future applications of human skin models and present methodological protocols to culture human skin equivalents and human skin explants.
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Modelos Biológicos , Pele , Animais , Humanos , Modelos AnimaisRESUMO
MicroRNAs play an important role in the interplay between bacterial pathogens and host cells, participating as host defense mechanisms, as well as exploited by bacteria to subvert host cellular functions. Here, we show that microRNAs modulate infection by Shigella flexneri, a major causative agent of bacillary dysentery in humans. Specifically, we characterize the dual regulatory role of miR-29b-2-5p during infection, showing that this microRNA strongly favors Shigella infection by promoting both bacterial binding to host cells and intracellular replication. Using a combination of transcriptome analysis and targeted high-content RNAi screening, we identify UNC5C as a direct target of miR-29b-2-5p and show its pivotal role in the modulation of Shigella binding to host cells. MiR-29b-2-5p, through repression of UNC5C, strongly enhances filopodia formation thus increasing Shigella capture and promoting bacterial invasion. The increase of filopodia formation mediated by miR-29b-2-5p is dependent on RhoF and Cdc42 Rho-GTPases. Interestingly, the levels of miR-29b-2-5p, but not of other mature microRNAs from the same precursor, are decreased upon Shigella replication at late times post-infection, through degradation of the mature microRNA by the exonuclease PNPT1. While the relatively high basal levels of miR-29b-2-5p at the start of infection ensure efficient Shigella capture by host cell filopodia, dampening of miR-29b-2-5p levels later during infection may constitute a bacterial strategy to favor a balanced intracellular replication to avoid premature cell death and favor dissemination to neighboring cells, or alternatively, part of the host response to counteract Shigella infection. Overall, these findings reveal a previously unappreciated role of microRNAs, and in particular miR-29b-2-5p, in the interaction of Shigella with host cells.
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Interações Hospedeiro-Patógeno/genética , MicroRNAs/genética , Shigella/genética , Shigella/virologia , Replicação Viral/genética , Linhagem Celular , Replicação do DNA/genética , Perfilação da Expressão Gênica/métodos , Interações Hospedeiro-Patógeno/imunologia , Humanos , Pseudópodes/imunologia , Interferência de RNA/fisiologiaRESUMO
Monoclonal IgG antibodies constitute the fastest growing class of therapeutics. Thus, there is an intense interest to design more potent antibody formats, where long plasma half-life is a commercially competitive differentiator affecting dosing, frequency of administration and thereby potentially patient compliance. Here, we report on an Fc-engineered variant with three amino acid substitutions Q311R/M428E/N434W (REW), that enhances plasma half-life and mucosal distribution, as well as allows for needle-free delivery across respiratory epithelial barriers in human FcRn transgenic mice. In addition, the Fc-engineered variant improves on-target complement-mediated killing of cancer cells as well as both gram-positive and gram-negative bacteria. Hence, this versatile Fc technology should be broadly applicable in antibody design aiming for long-acting prophylactic or therapeutic interventions.
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Neoplasias , Receptores Fc , Camundongos , Animais , Humanos , Imunoglobulina G , Meia-Vida , Antibacterianos/uso terapêutico , Bactérias Gram-Negativas/metabolismo , Bactérias Gram-Positivas/metabolismo , Camundongos Transgênicos , Anticorpos Monoclonais , Antígenos de Histocompatibilidade Classe I/metabolismo , Neoplasias/terapia , Neoplasias/tratamento farmacológicoRESUMO
Purpose: The restrictions imposed during lockdown by COVID-19 pandemic entailed increased risks for the perpetration of intimate partner violence (IPV). Widespread fear and uncertainty related to the virus and the policies adopted to contain it have been linked to a set of social, emotional, and economic stressors that can increase the risk of IPV. The present study aims to assess the association between COVID-19-related anxiety, psychological distress (depression, anxiety, and stress), and IPV perpetration in the community, as well as to assess the mediating role of psychological distress and depression, anxiety, and stress in the relationship between COVID-19-related anxiety and the perpetration of IPV. Methods: A sample of 336 participants (282 females, Mage = 34.91, SD = 11.72) was recruited from the Portuguese population through an online self-report questionnaire, completed after the second lockdown (from April and July 2021). Results: High rates of IPV perpetration during the confinement, in particular psychological and physical IPV, were found. COVID-19-related anxiety and psychological distress (depression, anxiety, and stress) were related to higher levels of IPV perpetration. Psychological distress and stress mediated the relationship between COVID-19-related anxiety and total IPV perpetration and psychological distress and depression mediated the relationship between COVID-19-related anxiety and psychological IPV perpetration. Conclusions: This study highlights the mediating role of psychological distress on IPV perpetration. Practical implications for intervention policies in IPV perpetration will be discussed.
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The extracellular region of the complement receptor of the Ig superfamily (CRIg) binds to certain C3 cleavage products (C3b, iC3b, C3c) and inhibits the alternative pathway (AP) of complement. In this study, we provide further insight into the CRIg protein and describe two CRIg mutants that lack multiple lysine residues as a means of facilitating chemical modifications of the protein. Structural analyses confirmed preservation of the native CRIg architecture in both mutants. In contrast to earlier reports suggesting that CRIg binds to C3b with an affinity of â¼1 µM, we found that wild-type CRIg binds to C3b and iC3b with affinities <100 nM, but to C3c with an affinity closer to 1 µM. We observed this same trend for both lysine substitution mutants, albeit with an apparent â¼2- to 3-fold loss of affinity when compared with wild-type CRIg. Using flow cytometry, we confirmed binding to C3 fragment-opsonized Staphylococcus aureus cells by each mutant, again with an â¼2- to 3-fold decrease when compared with wild-type. Whereas wild-type CRIg inhibits AP-driven lysis of rabbit erythrocytes with an IC50 of 1.6 µM, we observed an â¼3-fold reduction in inhibition for both mutants. Interestingly, we found that amine-reactive crosslinking of the CRIg mutant containing only a single lysine results in a significant improvement in inhibitory potency across all concentrations examined when compared with the unmodified mutant, but in a manner sensitive to the length of the crosslinker. Collectively, our findings provide new insights into the CRIg protein and suggest an approach for engineering increasingly potent CRIg-based inhibitors of the AP.
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Lisina , Receptores de Complemento , Animais , Coelhos , Receptores de Complemento/genética , Aminas , Complemento C3b , EritrócitosRESUMO
Ogilvie´s syndrome is a colonic dilation without any existing mechanical obstruction. The risk factors that cause it are not completely understood, but if untreated, the distension can result in rupture or ischaemic bowel perforation. Additionally, the existing guidelines do not agree with each other about the next steps if conservative treatment fails. We report the case of a 71-year-old woman in whom Ogilvie´s syndrome was particularly difficult to manage, and with it, we try to add clinical data to a field with scarce evidence.
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BACKGROUND: Prison sentences are a particular type of penalty that aim to reintegrate individuals into society. Nonetheless, research suggests that prison sentences have a null or a criminogenic effect on recidivism and a critical impact on inmates' mental health, negatively interfering with their successful reintegration into society and recidivism. Prevalence rates of mental health disorders among individuals who commit crimes are high, but little is known about how incarceration perpetuates and/or worsens mental health symptoms. In the Portuguese context, no studies focused on understanding the impact of imprisonment on prisoners' mental health. Thus, this project aims to understand incarceration's mental health and well-being impact on male and female individuals convicted to prison, both while incarcerated and after release. METHODS: The study will follow a quantitative cross-sectional design of male and female individuals in prison and parole, aiming to assess different samples at different moments of the prison sentence. It will also follow a longitudinal design in a subsample of male and female individuals sentenced to prison and on parole who will be followed for one year. DISCUSSION: This study intends to have a meaningful impact on the understanding of imprisonment effects, giving important clues for developing and implementing evidence-based prevention and intervention strategies to address prisoners' and ex-prisoners' mental health and improve their ability to successfully reintegrate into society and reduce recidivism.
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Transtornos Mentais , Prisioneiros , Humanos , Masculino , Feminino , Saúde Mental , Estudos Transversais , Prisões , Prisioneiros/psicologia , Transtornos Mentais/epidemiologiaRESUMO
BACKGROUND: Multiple sclerosis is a chronic neurological disease with increasing incidence and prevalence worldwide being the main cause of non-traumatic disability in young adults. Both acute and chronic pain have been mentioned as the most common symptoms among those patients. OBJECTIVE: This study was designed to evaluate the pain experience among patients with multiple sclerosis by describing its prevalence, characteristics, analgesic treatment and its efficacy, and also the impact of pain on quality of life. METHODS: A cross-sectional observation survey was carried out on patients with multiple sclerosis followed in a tertiary hospital. Data were collected between December 2019 and March 2021 from a structured telephone inquiry, applying two questionnaires, the Brief Pain Inventory and the McGill Pain Questionnaire (MPQ), to evaluate the prevalence of pain and its impact on quality of life (QoL). Clinical records were also consulted to obtain data on disease duration, year of diagnosis, MS type, Expanded Disability Status Scale (EDSS) score. RESULTS: Our sample included 305 patients in a universe of 1500, mainly women, with mean age of 44.27 years, and most of them presented with an outbreak-remission subtype of disease. One hundred twenty-four patients experienced pain which corresponds to 41% of the patients. Considering the patients who experienced pain, 67.7% were under treatment and of these, 64.3% with only one painkiller. Pain significantly interfered with general activity, mood, and regular work. CONCLUSION: Pain was an important symptom in this group of patients with MS and significantly interfered with mood, general activity, and regular work. The maximum intensity of pain felt by patients was significant and only 67.7% of patients were under analgesic treatment with mean pain relief of 54. NSAIDs were the most used drugs followed by gabapentinoids and acetaminophen for the management of pain. Medical community must continue to study this population in order to improve the approach to pain in these patients and improve quality of life.
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Pheochromocytomas and paragangliomas are rare neuroendocrine tumors. Pheochromocytomas are derived from chromaffin cells of the adrenal medulla, while paragangliomas arise from the extra-adrenal autonomic paraganglia. Paragangliomas can derive from either parasympathetic or sympathetic paraganglia. The majority of parasympathetic ganglia-derived paragangliomas are nonfunctional and symptoms arise from mass effect, while sympathetic paragangliomas are frequently functional and present with symptoms that result from catecholamine hypersecretion. Here, we present the case of a 19-year-old female with hypertension whose biochemical tests revealed elevated plasma and urinary levels of norepinephrine and normetanephrine. Imaging studies showed a left paravertebral mass which was surgically removed. Histopathology confirmed a paraganglioma. Total surgical resection remains the gold-standard treatment and a cure can be achieved; however, all tumors may harbor malignant potential, and a long-term biochemical and imaging follow-up is required in all patients. Screening for genetic germline mutations may be helpful in identifying patients with a higher risk of recurrence or of developing other primary tumors.
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Cannulation of the internal jugular vein is often necessary for the management of critically ill patients. Despite being a very common procedure and performed more and more safely, several complications still occur. Horner's Syndrome (HS) is one of those complications described before the use of ultrasound as a method of guidance. HS is caused by functional interruption of sympathetic nerve supply to the eye, leading to a classic triad of ipsilateral ptosis, miosis, and anhidrosis. We present the case of a patient, in need of emergent surgery to control the hemorrhagic focus after delivery, with a transient HS secondary to internal jugular vein cannulation under real-time ultrasound guidance.
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This study explores the narrative contents obtained from the description of autobiographical memories reported by a sample of incarcerated males that exemplified their most aggressive, transgressive, or criminal selves. Participants were 110 men serving a prison sentence for different types of crimes. Three main phenomena were identified from their stories: the narration of the criminal self, description of the crime (or crimes) committed, and the criminal responsibility attributional processes. The results showed the existence of mechanisms to justify the crime among a large section of participants, whereas the assumption of personal responsibility for the commission of the crime and the consideration of an unfair or excessive sentence were not as frequent. Also, some specific crimes concurred with concrete responsibility attributional processes, especially with the justification of criminal behavior. These findings generate useful information regarding recidivism, resocialization, and the attribution of responsibility among inmates.
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Criminosos , Prisioneiros , Crime , Comportamento Criminoso , Humanos , Masculino , NarraçãoRESUMO
Staphylococcal protein A (SpA) is a multifunctional, highly conserved virulence factor of Staphylococcus aureus. By binding the Fc portion of all human IgG subclasses apart from IgG3, SpA interferes with antibody and complement deposition on the bacterial surface, impairing staphylococcal clearance by phagocytosis. Because of its anti-opsonic properties, SpA is not investigated as a surface antigen to mediate bacterial phagocytosis. Herein we investigate human sera for the presence of SpA-opsonizing antibodies. The screening revealed that sera containing IgG3 against SpA were able to correctly opsonize the target and drive Fcγ receptor-mediated interactions and phagocytosis. We demonstrated that IgG3 Fc is significantly more efficient in inducing phagocytosis of SpA-expressing S. aureus as compared to IgG1 Fc in an assay resembling physiological conditions. Furthermore, we show that the capacity of SpA antibodies to induce phagocytosis depends on the specific epitope recognized by the IgGs on SpA molecules. Overall, our results suggest that anti-SpA IgG3 antibodies could favor the anti-staphylococcal response in humans, paving the way towards the identification of a correlate of protection against staphylococcal infections.
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Infecções Estafilocócicas , Proteína Estafilocócica A , Humanos , Imunoglobulina G , Proteínas Opsonizantes , Fagocitose , Staphylococcus , Staphylococcus aureusRESUMO
Staphylococcus aureus is the main cause of human skin and soft tissue infections. However, S. aureus pathogenicity within the skin is not fully characterized. Here, we implemented an S. aureus cutaneous infection model using human skin explants and performed a time-course infection to study the gene expression profile of a large panel of virulence-related factors of S. aureus USA300 LAC strain, by high-throughput RT-PCR. We pinpointed the genes that were differentially regulated by the bacteria in the skin tissues and identified 12 virulence factors that were upregulated at all time points assessed. Finally, using confocal microscopy, we show that the expression of alpha-hemolysin by S. aureus varies dependent on the skin niche and that the bacteria preferentially accumulates inside sweat glands and ducts. Taken together, our study gives insights about the pathogenic lifestyle of S. aureus within human skin tissues, which may contribute for the development of anti-S. aureus therapeutic strategies.
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Immunoglobulin G4 related-disease (IgG4-RD) is a multisystemic immune-mediated fibroinflammatory disease, with a strong predilection for salivary and lacrimal glands, pancreas, biliary tree, lungs, kidneys, aorta, and retroperitoneum. In the case of pancreatic involvement, it manifests as autoimmune pancreatitis. Patients with IgG4-RD usually have mild to moderate eosinophilia in the peripheral blood, however, they may present a secondary hypereosinophilic syndrome (HES). Although there are cases described with severe eosinophilia (> 5,000/µL), the 2019 American College of Rheumatology/European League Against Rheumatism classification criteria for IgG4-RD considers peripheral eosinophilia above 3,000/µL as an exclusion criterion, although stating that assessment for the presence of exclusion criteria should be individualized depending on a patient's clinical scenario. Here, we describe the clinical case of a 30-year-old woman who presented with chronic diarrhea and abdominal pain. The diagnostic workup revealed eosinophilic ascites, severe peripheral blood eosinophilia (> 5,000/µL), IgG4 elevation (> 2 × upper normal limit), and also diffuse swelling in the body and pancreatic tail (computed tomography (CT) scan). There was a prompt response to corticosteroid therapy with clinical resolution and continued remission under therapy. The patient was diagnosed with IgG4-RD with secondary HES, explaining the gastrointestinal tract and peritoneum damage in the form of enterocolitis and ascites. Exclusion of alternative diagnosis was made.
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Objective: This study aims to assess the feasibility and meaningfulness of a home-based individual cognitive stimulation (iCS) program delivered by caregivers to persons with cognitive impairment (PwCIs). It also aims to assess whether the older adults receiving this program improved their cognitive, neuropsychiatric, and depressive symptoms and quality of life and whether their caregivers improved their mental and physical health. Methods: A randomized controlled trial (RCT) was conducted with PwCI-caregiver dyads recruited from the community. Participants were allocated to two groups: intervention (n = 28) and control (n = 24). The intervention group received the European Portuguese version of the Individual Cognitive Stimulation Program-Making a Difference 3 (MD3-P). The control group received usual care. The iCS therapy program was implemented three times a week for 12 weeks. Caregivers were supported by the researchers to deliver the sessions at home. Participants were assessed at baseline and at the end of the intervention (week 13). Feasibility and meaningfulness were assessed through the attrition rate, adherence, and degree of satisfaction with the sessions. Four interviews were conducted (after week 13) to understand participants' experiences. Results: The attrition rate was 23.1%. The dyads reported that they did not have high expectations about the iCS program before starting the study. Nevertheless, as the program evolved, caregivers noted that their family members had improved some areas of functioning. Intention-to-treat analysis based on group differences revealed a significant improvement in PwCIs' cognition, specifically in their orientation and ability to follow commands. The intervention had no impact on other variables such as caregivers' physical and mental health. Conclusion: The iCS program implemented by caregivers showed promising results in improving PwCIs' cognition. The participants who completed the intervention attributed a positive meaning to the MD3-P, confirming it as a valid non-pharmacological therapeutic approach to reducing frailty in PwCIs in community settings. Clinical Trial Registration: www.ClinicalTrials.gov, identifier [NCT03514095].
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Intimate partner violence (IPV) is a highly prevalent phenomenon worldwide and is considered a severe violation of human rights. Intimate partner homicide (IPH) and attempted intimate partner homicide (AIPH) although less frequent have a severe direct or indirect impact on victims. Despite the vast literature on IPV and IPH, there is still scarce research on AIPH. Thus, this study aimed to analyze whether perpetrators of IPV, IPH, and AIPH differ from each other, as well as to identify the factors that predict violence in intimacy. For those purposes, we performed a comparative analysis between 50 male individuals convicted of IPH, 27 convicted of AIPH, and 168 convicted of IPV from Portugal. The data were collected using an interview and a set of psychological measures. Results revealed that, although IPV, IPH, and AIPH perpetrators' share some characteristics, significant differences were found between them. IPV perpetrators were more prone to perpetrate violent behaviors against an intimate partner or ex-partner than IPH or AIPH offenders. The use of weapons and separation from the victim increases the probability of committing IPH or AIPH. Being divorced, having no children, and committing other crimes than domestic violence are predictors of AIPH. These results have some practical implications, in terms of both risk prediction and risk management. Accurate and comprehensive tools should be included as a routine in the primary care services, as well as in the child care services and in victim support services. Prevention and intervention efforts must be comprehensive, involving work with perpetrators and victims.
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Criminosos , Violência Doméstica , Violência por Parceiro Íntimo , Feminino , Homicídio , Humanos , Masculino , Parceiros SexuaisRESUMO
The skin is an immunocompetent tissue that harbors several kinds of immune cells and a plethora of commensal microbes constituting the skin microbiome. Staphylococcus aureus is a prominent skin pathogen that colonizes a large proportion of the human population. We currently have an incomplete understanding of the correlates of protection against S. aureus infection, however genetic and experimental evidence has shown that CD4+ T cells play a key role in orchestrating a protective anti-S. aureus immune response. A high S. aureus-specific memory CD4+ T cell response has been reported in the blood of healthy subjects. Since T cells are more abundant in the skin than in blood, we hypothesized that S. aureus-specific CD4+ T cells could be present in the skin of healthy individuals. Indeed, we observed proliferation of tissue-resident memory CD4+ T cells and production of IL-17A, IL-22, IFN-γ and TNF-ß by cells isolated from abdominal skin explants in response to heat-killed S. aureus. Remarkably, these cytokines were produced also during an ex vivo epicutaneous S. aureus infection of human skin explants. These findings highlight the importance of tissue-resident memory CD4+ T cells present at barrier sites such as the skin, a primary entry site for S. aureus. Further phenotypical and functional characterization of these cells will ultimately aid in the development of novel vaccine strategies against this elusive pathogen.