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Natural killer (NK) cells recognize and kill target cells undergoing different types of stress. NK cells are also capable of modulating immune responses. In particular, they regulate T cell functions. Small RNA next-generation sequencing of resting and activated human NK cells and their secreted extracellular vesicles (EVs) led to the identification of a specific repertoire of NK-EV-associated microRNAs and their post-transcriptional modifications signature. Several microRNAs of NK-EVs, namely miR-10b-5p, miR-92a-3p, and miR-155-5p, specifically target molecules involved in Th1 responses. NK-EVs promote the downregulation of GATA3 mRNA in CD4 + T cells and subsequent TBX21 de-repression that leads to Th1 polarization and IFN-γ and IL-2 production. NK-EVs also have an effect on monocyte and moDCs (monocyte-derived dendritic cells) function, driving their activation and increased presentation and costimulatory functions. Nanoparticle-delivered NK-EV microRNAs partially recapitulate NK-EV effects in mice. Our results provide new insights on the immunomodulatory roles of NK-EVs that may help to improve their use as immunotherapeutic tools.

With apparent declines in malaria worldwide during the last decade and more widespread use of malaria rapid diagnostic tests, healthcare workers in low-resource areas face a growing proportion of febrile patients without malaria. We sought to describe current knowledge and identify information gaps of the etiology severe febrile illness in low-and middle-income countries. We conducted a systematic review of studies conducted in low-and-middle income countries 1980-2013 that prospectively assessed consecutive febrile patients admitted to hospital using rigorous laboratory-based case definitions. We found 45 eligible studies describing 54,578 patients; 9,771 (17.9%) had a positive result for ≥1 pathogen meeting diagnostic criteria. There were no eligible studies identified from Southern and Middle Africa, Eastern Asia, Oceania, Latin American and Caribbean regions, and the European region. The median (range) number of diagnostic tests meeting our confirmed laboratory case definitions was 2 (1 to 11) per study. Of diagnostic tests, 5,052 (10.3%) of 49,143 had confirmed bacterial or fungal bloodstream infection; 709 (3.8%) of 18,142 had bacterial zoonosis; 3,488 (28.5%) of 12,245 had malaria; and 1,804 (17.4%) of 10,389 had a viral infection. We demonstrate a wide range of pathogens associated with severe febrile illness and highlight the substantial information gaps regarding the geographic distribution and role of common pathogens. High quality severe febrile illness etiology research that is comprehensive with respect to pathogens and geographically representative is needed.

In this study from sub-Saharan Africa, children with severe febrile illness and impaired perfusion were randomly assigned to fluid-bolus therapy or no bolus. Albumin or saline boluses significantly increased 48-hour mortality in critically ill children with impaired perfusion. Rapid, early fluid resuscitation in patients with shock, a therapy that is aimed at the correction of hemodynamic abnormalities, is one component of goal-driven emergency care guidelines. This approach is widely endorsed by pediatric life-support training programs, which recommend the administration of up to 60 ml of isotonic fluid per kilogram of body weight within 15 minutes after the diagnosis of shock. 1 Children who do not have an adequate response to fluid resuscitation require intensive care for inotropic and ventilatory support. 1 Substantial improvements in the outcomes of pediatric septic shock have been attributed to this approach. 2 , 3 Nevertheless, evidence regarding . . .

The pandemic, due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has stimulated the search for antivirals to tackle COVID-19 infection. Molecules with known pharmacokinetics and already approved for human use have been demonstrated or predicted to be suitable to be used either directly or as a base for a scaffold-based drug design. Among these substances, quercetin is known to be a potent in vitro inhibitor of 3CLpro, the SARS-CoV-2 main protease. However, its low in vivo bioavailability calls for modifications to its molecular structure. In this work, this issue is addressed by using rutin, a natural flavonoid that is the most common glycosylated conjugate of quercetin, as a model. Combining experimental (spectroscopy and calorimetry) and simulation techniques (docking and molecular dynamics simulations), we demonstrate that the sugar adduct does not hamper rutin binding to 3CLpro, and the conjugated compound preserves a high potency (inhibition constant in the low micromolar range, Ki = 11 μM). Although showing a disruption of the pseudo-symmetry in the chemical structure, a larger steric volume and molecular weight, and a higher solubility compared to quercetin, rutin is able to associate in the active site of 3CLpro, interacting with the catalytic dyad (His41/Cys145). The overall results have implications in the drug-design of quercetin analogs, and possibly other antivirals, to target the catalytic site of the SARS-CoV-2 3CLpro.

The immune effector mechanisms involved in protecting against severe COVID-19 infection in elderly nursing home residents following vaccination or natural infection are not well understood. Here, we measured SARS-CoV-2 Spike (S)-directed functional antibody responses, including neutralizing antibodies (NtAb) and antibody Fc-mediated NK cell activity (degranulation and IFNγ production), against the Wuhan-Hu-1, BA.4/5 (for NtAb), and Omicron XBB.1.5 variants in elderly nursing home residents (n = 39; median age, 91 years) before and following a third (pre- and post-3D) and a fourth (pre- and post-4D) mRNA COVID-19 vaccine dose. Both 3D and 4D boosted NtAb levels against both (sub)variants. Likewise, 3D and 4D increased the ability of sera to trigger both LAMP1- and IFNγ-producing NK cells, in particular against XBB.1.5. In contrast to NtAb titres, the frequencies of LAMP1- and IFNγ-producing NK cells activated by antibodies binding to Wuhan-Hu-1 and Omicron XBB.1.5 S were comparable at all testing times. Stronger functional antibody responses were observed in vaccine-experienced participants compared to vaccine-naïve at some testing times. These findings can contribute to identifying a reliable correlate of protection in elderly nursing home residents against severe COVID-19 and inform future vaccine strategies in this population group.

Many activating immunoreceptors associate with signaling adaptor molecules like FcεR1γ or CD247. FceR1γ and CD247 share high sequence homology and form disulphide-linked homodimers that contain a pair of acidic aspartic acid residues in their transmembrane (TM) domains that mediate assembly, via interaction with an arginine residue at a similar register to these aspartic acids, with the activating immunoreceptors. However, this model cannot hold true for receptors like CD16A, whose TM domains do not contain basic residues. We have carried out an extensive site-directed mutagenesis analysis of the CD16A receptor complex and now report that the association of receptor with the signaling adaptor depends on a network of polar and aromatic residues along the length of the TM domain. Molecular modeling indicates that CD16A TM residues F202, D205, and T206 form the core of the membrane-embedded trimeric interface by establishing highly favorable contacts to the signaling modules through rearrangement of a hydrogen bond network previously identified in the CD247 TM dimer solution NMR structure. Strikingly, the amino acid D205 also regulates the turnover and surface expression of CD16A in the absence of FcεR1γ or CD247. Modeling studies indicate that similar features underlie the association of other activating immune receptors, including CD64 and FcεR1α, with signaling adaptor molecules, and we confirm experimentally that equivalent F, D, and T residues in the TM domain of FcεR1α markedly influence the biology of this receptor and its association with FcεR1γ.

The NKG2DL consist of the multicopy major histocompatibility complex (MHC) Class I-related chain (MIC) and UL16 binding protein (ULBP) gene families. The observed variation in the receptor/ligand molecules of the NKG2D/NKG2DL axis likely reflects a complex hierarchical system of interactions that is still not completely understood, but mirrors another highly variable system involving the related human leucocyte antigen (HLA) class I molecules and the inhibitory and activating killer immunoglobulin-like receptors (KIRs) (3) on the same target/effector cells. Conflict of interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

It is now clear that coronavirus disease 19 (COVID-19) severity is associated with a dysregulated immune response, but the relative contributions of different immune cells is still not fully understood. SARS CoV-2 infection triggers marked changes in NK cell populations, but there are contradictory reports as to whether these effector lymphocytes play a protective or pathogenic role in immunity to SARS-CoV-2. To address this question we have analysed differences in the phenotype and function of NK cells in SARS-CoV-2 infected individuals who developed either very mild, or life-threatening COVID-19 disease. Although NK cells from patients with severe disease appeared more activated and the frequency of adaptive NK cells was increased, they were less potent mediators of ADCC than NK cells from patients with mild disease. Further analysis of peripheral blood NK cells in these patients revealed that a population of NK cells that had lost expression of the activating receptor NKG2D were a feature of patients with severe disease and this correlated with elevated levels of cell free NKG2D ligands, especially ULBP2 and ULBP3 in the plasma of critically ill patients. In vitro, culture in NKG2DL containing patient sera reduced the ADCC function of healthy donor NK cells and this could be blocked by NKG2DL-specific antibodies. These observations of reduced NK function in severe disease are consistent with the hypothesis that defects in immune surveillance by NK cells permit higher levels of viral replication, rather than that aberrant NK cell function contributes to immune system dysregulation and immunopathogenicity.

( ) uses various strategies that attenuate mucosal immunity to ensure its persistence in the stomach. We recently found evidence that might modulate the natural killer group 2, member 2 (NKG2D) system. The NKG2D receptor and its ligands are a major activation system of natural killer and cytotoxic T cells, which are important for mucosal immunity and tumor immunosurveillance. The NKG2D system allows recognition and elimination of infected and transformed cells, however viruses and cancers often subvert its activation. Here we aimed to identify a potential evasion of the NKG2D system in infection. We analyzed expression of NKG2D system genes in gastric tissues of gastritis and gastric cancer patients, and performed cell-culture based infection experiments using isogenic mutants and epithelial and NK cell lines. In biopsies of gastritis patients, NKG2D receptor expression was reduced while NKG2D ligands accumulated in the lamina propria, suggesting NKG2D evasion. , induced the transcription and proteolytic shedding of NKG2D ligands in stomach epithelial cells, and these effects were associated with specific virulence factors. The -driven release of soluble NKG2D ligands reduced the immunogenic visibility of infected cells and attenuated the cytotoxic activity of effector immune cells, specifically the anti-tumor activity of NK cells. manipulates the NKG2D system. This so far unrecognized strategy of immune evasion by could potentially facilitate chronic bacterial persistence and might also promote stomach cancer development by allowing transformed cells to escape immune recognition and grow unimpeded to overt malignancy.

The short-lived nature and heterogeneity of Natural Killer (NK) cells limit the development of NK cell-based therapies, despite their proven safety and efficacy against cancer. Here, we describe the biological basis, detailed phenotype and function of long-lived anti-tumour human NK cells (CD56 high CD16 + ), obtained without cell sorting or feeder cells, after priming of peripheral blood cells with Bacillus Calmette-Guérin (BCG). Further, we demonstrate that survival doses of a cytokine combination, excluding IL18, administered just weekly to BCG-primed NK cells avoids innate lymphocyte exhaustion and leads to specific long-term proliferation of innate cells that exert potent cytotoxic function against a broad range of solid tumours, mainly through NKG2D. Strikingly, a NKG2C + CD57 - FcεRIγ + NK cell population expands after BCG and cytokine stimulation, independently of HCMV serology. This strategy was exploited to rescue anti-tumour NK cells even from the suppressor environment of cancer patients’ bone marrow, demonstrating that BCG confers durable anti-tumour features to NK cells.