Biology subjects

Bafica, A.

Publications and source records attributed to Bafica, A..

6 recordsLinked to original sources

bioRxiv2020

Neuraminidase inhibitors rewire neutrophil function in murine sepsis and COVID-19 patient cells

Neutrophil overstimulation plays a crucial role in tissue damage during severe infections. Neuraminidase (NEU)-mediated cleavage of surface sialic acid has been demonstrated to regulate leukocyte responses. Here, we report that antiviral NEU inhibitors constrain host NEU activity, surface sialic acid release, ROS production, and NETs released by microbial-activated human neutrophils. In vivo, treatment with Oseltamivir results in infection control and host survival in peritonitis and pneumonia models of sepsis. Single-cell RNA sequencing re-analysis of publicly data sets of respiratory tract samples from critical COVID-19 patients revealed an overexpression of NEU1 in infiltrated neutrophils. Moreover, Oseltamivir or Zanamivir treatment of whole blood cells from severe COVID-19 patients reduces host NEU-mediated shedding of cell surface sialic acid and neutrophil overactivation. These findings suggest that neuraminidase inhibitors can serve as host-directed interventions to dampen neutrophil dysfunction in severe infections. At a GlanceIn a severe systemic inflammatory response, such as sepsis and COVID-19, neutrophils play a central role in organ damage. Thus, finding new ways to inhibit the exacerbated response of these cells is greatly needed. Here, we demonstrate that in vitro treatment of whole blood with the viral neuraminidase inhibitors Oseltamivir or Zanamivir, inhibits the activity of human neuraminidases as well as the exacerbated response of neutrophils. In experimental models of severe sepsis, oseltamivir decreased neutrophil activation and increased the survival rate of mice. Moreover, Oseltamivir or Zanamivir ex vivo treatment of whole blood cells from severe COVID-19 patients rewire neutrophil function.

immunology↗

bioRxiv2019

Flaviviruses exploit fine-tuning of the interferon response to promote replication

The establishment of a virus infection is the result of the pathogens ability to replicate in a hostile environment generated by the hosts immune system. Here, we found that ISG15 restricts Dengue and Zika viruses replication through the stabilisation of its binding partner USP18. ISG15 expression was necessary to control DV replication driven by both autocrine and paracrine type one interferon (IFN-I) signalling. Moreover, USP18 competes with NS5-mediated STAT2 degradation, a major mechanism for establishment of flavivirus infection. Strikingly, reconstitution of USP18 in ISG15-deficient cells was sufficient to restore the STAT2s stability and restrict virus growth, suggesting that the IFNAR-mediated ISG15 activity is also antiviral. Our results add a novel layer of complexity in the virus/host interaction interface and suggest that NS5 has a narrow window of opportunity to degrade STAT2, therefore suppressing hosts IFN-I mediated response and promoting virus replication. IMPORTANCEDisease is an emergent property that results from a microorganisms ability to replicate in a given host and the latters immune response. Here we describe how the immunoregulatory function of ISG15 (an interferon stimulated gene) affects Dengue and Zika virus replication by occupying a niche used by the virus non-structural protein 5 (NS5) to evade hosts immunity. In the absence of ISG15, NS5 efficiently degrades a main signalling hub of innate immunity (STAT2), leading to cell immune suppression and consequently virus growth. This sheds light into how flaviviruses intimately interact with the host immune system and could lead to a host-based therapy target.

immunology↗

bioRxiv2019

Mycobacterium tuberculosis hijacks an evolutionary recent IFN-IL-6-CEBP axis linked to monocyte development and disease severity in humans

Monocyte counts are increased during human tuberculosis (TB) but it has not been determined whether Mycobacterium tuberculosis (Mtb) directly regulates myeloid commitment. We demonstrated that exposure to Mtb directs primary human CD34+ cells to differentiate into monocytes/macrophages. In vitro myeloid conversion did not require type I or type II IFN signaling. In contrast, Mtb enhanced IL-6 responses by CD34+ cell cultures and IL-6R neutralization inhibited myeloid differentiation and decreased mycobacterial growth in vitro. Integrated systems biology analysis of transcriptomic, proteomic and genomic data of large data sets of healthy controls and TB patients established the existence of a myeloid IL-6/IL6R/CEBP gene module associated with disease severity. Furthermore, genetic and functional analysis revealed the IL6/IL6R/CEBP gene module has undergone recent evolutionary selection, including Neanderthal introgression and human pathogen adaptation, connected to systemic monocyte counts. These results suggest Mtb co-opts an evolutionary recent IFN-IL6-CEBP feed-forward loop, increasing myeloid differentiation linked to severe TB in humans.

immunology↗

bioRxiv2018

Vasculature-associated adipose tissue macrophages dynamically adapt to inflammatory and metabolic challenges

Tissue-resident macrophages comprise the most abundant immune cell population in healthy adipose tissue. Adipose tissue macrophage populations change during metabolic stress and ageing, and are thought to contribute to the pathogenesis of obesity. Here, we studied adipose tissue macrophage subpopulations in the steady state, and in response to nutritional and infectious challenges.\n\nUsing comprehensive cell-surface-based and gene expression analyses, we found that tissue-resident macrophages from healthy epididymal white adipose tissue (eWAT) tightly associate with blood vessels, displaying a very high endocytic capacity. We refer to these cells as Vasculature-associated Adipose tissue Macrophages (VAMs). Chronic high fat diet (HFD) feeding results in the accumulation of a monocyte-derived CD11c+CD64+ double positive (DP) macrophage eWAT population with a predominant anti-inflammatory gene profile, but reduced endocytic function. In contrast, fasting rapidly and reversibly leads to VAM depletion, while acute inflammatory stress induced by pathogens transiently depletes VAMs and simultaneously boosts DP macrophage accumulation. Our results indicate that adipose tissue macrophage populations adapt to metabolic stress and inflammation, suggesting an important role for these cells in restoring homeostasis.

immunology↗

bioRxiv2017

RSV Downregulates IL-21/IL-21R On TFH Cells Via PD-L1 Induction In APCs Impairing Protective Humoral Responses

Respiratory syncytial virus (RSV) is the major cause of hospitalization for children under two years of age. RSV vaccines are currently unavailable, and children suffering from multiple reinfections by the same viral strain, fail to develop protective memory responses. Follicular helper T (TFH) cells specialize in providing B cell help to antibody production and affinity maturation, mainly via IL-21 secretion. Although RSV-specific antibodies can be detected upon infection, how they are generated and their relevance against disease protection has not been fully examined. Here, we observed that RSV expands a functionally impaired murine TFH cell population in vitro and vivo, with downregulated IL-21R expression and IL-21 production. IL-21 treatment of RSV-infected mice, however, increased TFH cells frequency, enhanced the germinal center reaction and improved protective humoral immune responses by increasing viral protein F specific antibody avidity and neutralization capacity. In vivo, it protected from RSV infection, decreasing lung inflammation. Passive immunization with purified IgG from IL-21 treated RSV-infected mice protected against RSV infection. Both viable and UV-inactivated RSV induced PD-L1 expression on B cells and DCs, however, only in DCs a direct effect of RSV was detected. Blocking PD-L1 during infection recovered IL-21R expression in TFH and B cells and increased secretion of IL-21 by TFH cells in a DC-dependent manner. Our results unveil a novel pathway by which RSV affects TFH cells activity, reducing levels of IL-21 and its receptor, by increasing PD-L1 expression on APCs. These results highlight the PD-L1/IL-21 axis importance for the generation of protective responses to RSV infection.\n\n\n\nO_FIG O_LINKSMALLFIG WIDTH=176 HEIGHT=200 SRC=\"FIGDIR/small/203133_figGA1.gif\" ALT=\"Figure 1\">\nView larger version (36K):\norg.highwire.dtl.DTLVardef@172470eorg.highwire.dtl.DTLVardef@197017eorg.highwire.dtl.DTLVardef@e31ae3org.highwire.dtl.DTLVardef@1fa4c4f_HPS_FORMAT_FIGEXP M_FIG GRAPHICAL ABSTRACTRSV infection impairing IL-21 secretion by TFH cells via PD-L1induction in dendritic cells and B cells. Low levels of IL-21 lead to poor RSV-specific humoral immune responses, low antibody titer, avidity and neutralization capacity. PD-L1 blockade can upregulate IL-21 secretion, and IL-21 treatment restores the entire immune humoral responses, resulting in protection against RSV infection.\n\nC_FIG

immunology↗

bioRxiv2017

ISG15 induces IL-10 production in human monocytes and is a biomarker of disease severity during active tuberculosis

Interferon stimulated gene 15 (ISG15) deficiency in humans leads to severe interferonopathies and mycobacterial disease, the latter being previously associated to its extracellular cytokine-like activity. Here, we demonstrate a novel role for secreted ISG15 as an IL-10 inducer, unique to human primary monocytes. Employing ex vivo systems analysis of human transcriptome datasets, we observed a significant correlation of ISG15-induced monocyte IL-10 and lymphocyte IFN{gamma} balanced expression. This effect was associated with p38 MAPK and PI3K signalling in healthy volunteers. The specificity and MAPK/PI3K-dependence of ISG15-induced monocyte IL-10 production was confirmed in vitro using CRISPR/Cas9 knockout and pharmacological inhibitors. Moreover, this ISG15/IL10 axis was amplified in leprosy but disrupted in human active tuberculosis (TB) patients. Importantly, ISG15 strongly correlated with inflammation and disease severity during active TB. In conclusion, this study identifies a novel anti-inflammatory ISG15/IL-10 myeloid axis that is disrupted in active TB, revealing a potential biomarker for disease severity in this major human disease.

immunology↗