Regulation of dendritic cell functions is a complex process in which several mediators play diverse roles as a network in a context-dependent manner. The precise mechanisms underlying dendritic cell ...functions have remained to be addressed. Semaphorins play crucial roles in regulation of various cell functions. We previously revealed that Semaphorin 3E (Sema3E) contributes to regulation of allergen-induced airway pathology partly mediated by controlling recruitment of conventional dendritic cell subsets in vivo, though the underlying mechanism remained elusive. In this study, we investigate the potential regulatory role of Sema3E in dendritic cells. We demonstrated that bone marrow-derived dendritic cells differentiated from Sema3e.sup.-/- progenitors have an enhanced migration capacity both at the baseline and in response to CCL21. The enhanced migration ability of Sema3E dendritic cells was associated with an overexpression of the chemokine receptor (CCR7), elevated Rac1 GTPase activity and F-actin polymerization. Using a mouse model of allergic airway sensitization, we observed that genetic deletion of Sema3E leads to a time dependent upregulation of CCR7 on CD11b.sup.+ conventional dendritic cells in the lungs and mediastinal lymph nodes. Furthermore, aeroallergen sensitization of Sema3e.sup.-/- mice lead to an enhanced expression of PD-L2 and IRF-4 as well as enhanced allergen uptake in pulmonary CD11b.sup.+ DC, compared to wild type littermates. Collectively, these data suggest that Sema3E implicates in regulation of dendritic cell functions which could be considered a basis for novel immunotherapeutic strategies for the diseases associated with defective dendritic cells in the future.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Dendritic cells (DC) connect the innate and adaptive arms of the immune system and carry out numerous roles that are significant in the context of viral disease. Their functions include the control ...of inflammatory responses, the promotion of tolerance, cross-presentation, immune cell recruitment and the production of antiviral cytokines. Based primarily on the available literature that characterizes the behaviour of many DC subsets during Severe acute respiratory syndrome (SARS) and coronavirus disease 2019 (COVID-19), we speculated possible mechanisms through which DC could contribute to COVID-19 immune responses, such as dissemination of Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to lymph nodes, mounting dysfunctional inteferon responses and T cell immunity in patients. We highlighted gaps of knowledge in our understanding of DC in COVID-19 pathogenesis and discussed current pre-clinical development of therapies for COVID-19.
TRAIL is an apoptosis-inducing ligand constitutively expressed on liver-resident type 1 innate lymphoid cells (ILC1s) and a subset of natural killer (NK) cells, where it contributes to NK cell ...anti-tumor, anti-viral, and immunoregulatory functions. However, the intrinsic pathways involved in TRAIL expression in ILCs remain unclear. Here, we demonstrate that the murine natural cytotoxic receptor mNKp46/NCR1, expressed on ILC1s and NK cells, controls TRAIL protein expression. Using NKp46-deficient mice, we show that ILC1s lack constitutive expression of TRAIL protein and that NK cells activated in vitro and in vivo fail to upregulate cell surface TRAIL in the absence of NKp46. We show that NKp46 regulates TRAIL expression in a dose-dependent manner and that the reintroduction of NKp46 in mature NK cells deficient for NKp46 is sufficient to restore TRAIL surface expression. These studies uncover a link between NKp46 and TRAIL expression in ILCs with potential implications in pathologies involving NKp46-expressing cells.
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•NKp46-deficient mice lack constitutive expression of TRAIL on liver resident ILC1s•NKp46-deficient splenic NK cells fail to induce cell surface TRAIL upon activation•NKp46 regulates TRAIL expression at a post-translational level•Transduction of NKp46 in primary NK cells restores TRAIL surface expression
Sheppard et al. find that mice deficient in the activating receptor NCR1/NKp46 (Ncr1−/−) fail to express the apoptosis-inducing ligand TRAIL at the surface of group 1 innate lymphoid cells (ILC1s).
COVID-19 and influenza both cause enormous disease burdens, and vaccines are the primary measures for their control. Since these viral diseases are transmitted through the mucosal surface of the ...respiratory tract, developing an effective and convenient mucosal vaccine should be a high priority. We previously reported a recombinant vesicular stomatitis virus (rVSV)-based bivalent vaccine (v-EM2/SPΔC1Delta) that protects animals from both SARS-CoV-2 and influenza viruses via intramuscular and intranasal immunization. Here, we further investigated the immune response induced by oral immunization with this vaccine and its protective efficacy in mice. The results demonstrated that the oral delivery, like the intranasal route, elicited strong and protective systemic immune responses against SARS-CoV-2 and influenza A virus. This included high levels of neutralizing antibodies (NAbs) against SARS-CoV-2, as well as strong anti-SARS-CoV-2 spike protein (SP) antibody-dependent cellular cytotoxicity (ADCC) and anti-influenza M2 ADCC responses in mice sera. Furthermore, it provided efficient protection against challenge with influenza H1N1 virus in a mouse model, with a 100% survival rate and a significantly low lung viral load of influenza virus. All these findings provide substantial evidence for the effectiveness of oral immunization with the rVSV bivalent vaccine.
Migration and localization of NK cells into peripheral tissues are tightly regulated under normal and pathological conditions. The physiological importance of NK cell–DC crosstalk has been well ...documented. However, the ways in which DCs regulate the migratory properties of NK cells (such as chemotaxis, chemokinesis, chemo‐repulsion) are not fully defined in vitro. Here, we employed a microfluidic platform to examine, at the single‐cell level, C57BL/6 NK‐cell migrations in a stable chemical gradient. We observed that soluble factors released by the immature and LPS‐activated mature DCs induced a high level of chemotactic movement of IL‐2‐activated NK cells in vitro. We confirmed these findings in a standard trans‐well migration assay, and identified CXCR3 as a key receptor on the NK cells that mediated the migration. More interestingly, we revealed a novel function of granulocyte macrophage colony‐stimulating factor in repulsing NK‐cell migrations. The future uses of such microfluidic device in the systematic evaluations of NK‐cell migratory responses in NK cell–DC crosstalk will provide new insights into the development of DC‐based NK‐cell therapies against tumor and infections.
Semaphorin-3E (Sema-3E) is a member of a large family of proteins originally identified as axon guidance cues in neural development. It is expressed in different cell types, such as immune cells, ...cancer cells, neural cells, and epithelial cells. Subsequently, dys-regulation of Sema-3E expression has been reported in various biological processes that range from cancers to autoimmune and allergic diseases. Recent work in our laboratories revealed a critical immunoregulatory role of Sema-3E in experimental allergic asthma. We further speculate possible immune modulatory function(s) of Sema-3E on natural killer (NK) cells.
NK cells are key innate immune cells that play critical roles in host defense. Although NK cells have been shown to regulate immunity to some infectious diseases, their role in immunity to
has not ...been investigated. NK cells are vital sources of IFN-γ and TNF-α; two key cytokines that are known to play important roles in resistance to African trypanosomes. In this article, we show that infection with
leads to increased levels of activated and functional NK cells in multiple tissue compartments. Systemic depletion of NK cells with anti-NK1.1 mAb led to increased parasitemia, which was accompanied by significant reduction in IFN-γ production by immune cells in the spleens and liver of infected mice. Strikingly, infected NFIL3
mice (which genetically lack NK cell development and function) on the normally resistant background were highly susceptible to
infection. These mice developed fulminating and uncontrolled parasitemia and died significantly earlier (13 ± 1 d) than their wild-type control mice (106 ± 26 d). The enhanced susceptibility of NFIL3
mice to infection was accompanied by significantly impaired cytokine (IFN-γ and TNF-α) response by CD3
T cells in the spleens and liver. Adoptive transfer of NK cells into NFIL3
mice before infection rescued them from acute death in a perforin-dependent manner. Collectively, these studies show that NK cells are critical for optimal resistance to
, and its deficiency leads to enhanced susceptibility in infected mice.
c-Myc is a highly pleiotropic transcription factor known to control cell cycle progression, apoptosis, and cellular transformation. Normally, ectopic expression of c-Myc is associated with promoting ...cell proliferation or triggering cell death via activating p53. However, it is not clear how the levels of c-Myc lead to different cellular responses. Here, we generated a series of stable RPE cell clones expressing c-Myc at different levels, and found that consistent low level of c-Myc induced cellular senescence by activating AP4 in post-confluent RPE cells, while the cells underwent cell death at high level of c-Myc. In addition, high level of c-Myc could override the effect of AP4 on cellular senescence. Further knockdown of AP4 abrogated senescence-like phenotype in cells expressing low level of c-Myc, and accelerated cell death in cells with medium level of c-Myc, indicating that AP4 was required for cellular senescence induced by low level of c-Myc.
Certain short peptides do not occur in humans and are rare or non-existent in the universal proteome. Antigens that contain rare amino acid sequences are in general highly immunogenic and may ...activate different arms of the immune system. We first generated a list of rare, semi-common, and common 5-mer peptides using bioinformatics tools to analyze the UniProtKB database. Experimental observations indicated that rare and semi-common 5-mers generated stronger cellular responses in comparison with common-occurring sequences. We hypothesized that the biological process responsible for this enhanced immunogenicity could be used to positively modulate immune responses with potential application for vaccine development. Initially, twelve rare 5-mers, 9-mers, and 13-mers were incorporated in frame at the end of an H5N1 hemagglutinin (HA) antigen and expressed from a DNA vaccine. The presence of some 5-mer peptides induced improved immune responses. Adding one 5-mer peptide exogenously also offered improved clinical outcome and/or survival against a lethal H5N1 or H1N1 influenza virus challenge in BALB/c mice and ferrets, respectively. Interestingly, enhanced anti-HBsAg antibody production by up to 25-fold in combination with a commercial Hepatitis B vaccine (Engerix-B, GSK) was also observed in BALB/c mice. Mechanistically, NK cell activation and dependency was observed with enhancing peptides ex vivo and in NK-depleted mice. Overall, the data suggest that rare or non-existent oligopeptides can be developed as immunomodulators and supports the further evaluation of some 5-mer peptides as potential vaccine adjuvants.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Natural killer (NK) cells and dendritic cells (DCs) are two innate immune cells that are critical in regulating innate and adaptive immunity. Cellular functions and migratory responses of NK or DC ...can be further regulated in NK-DC crosstalk that involves multiple cytokine signals and/or direct cell-cell contacts. Semaphorin-3E (Sema-3E) is a member of a large family of Semaphorin proteins that play diverse regulatory functions in different biological systems upon its binding to the cognate receptors. However, possible role(s) of Sema-3E on the regulation of NK-cell functions has not been elucidated. Here, we first demonstrated that DC and NK cells expressed Sema-3E and its receptors, respectively. To formally address the importance of DC-derived Sema-3E in regulating NK-cell migration, we compared
migratory responses of activated NK cells (aNKs) toward different conditioned media of DCs (immature, lipopolysaccharide- or Poly I:C-stimulated) derived from Sema-3E
or Sema-3E
mice. We observed that aNKs exhibited enhanced migrations toward the conditioned medium of the immature Sema-3E
DC, when compared with that of the immature Sema-3E
DC. Addition of exogenous recombinant Sema-3E to the conditioned medium of the Sema-3E
immature DC (iDC) abrogated such enhanced NK-cell migration. Our current work revealed a novel role of Sema-3E in limiting NK-cell migrations toward iDC in NK-DC crosstalk.
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