GNUV201, a novel human/mouse cross-reactive and low pH-selective anti-PD-1 monoclonal antibody for cancer immunotherapy.

BACKGROUND: Several PD-1 antibodies approved as anti-cancer therapies work by blocking the interaction of PD-1 with its ligand PD-L1, thus restoring anti-cancer T cell activities. These PD-1 antibodies lack inter-species cross-reactivity, necessitating surrogate antibodies for preclinical studies, which may limit the predictability and translatability of the studies. RESULTS: To overcome this limitation, we have developed an inter-species cross-reactive PD-1 antibody, GNUV201, by utilizing an enhanced diversity mouse platform (SHINE MOUSE™). GNUV201 equally binds to human PD-1 and mouse PD-1, equally inhibits the binding of human PD-1/PD-L1 and mouse PD-1/PD-L1, and effectively suppresses tumor growth in syngeneic mouse models. The epitope of GNUV201 mapped to the "FG loop" of hPD-1, distinct from those of Keytruda® ("C'D loop") and Opdivo® (N-term). Notably, the structural feature where the protruding epitope loop fits into GNUV201's binding pocket supports the enhanced binding affinity due to slower dissociation (8.7 times slower than Keytruda®). Furthermore, GNUV201 shows a stronger binding affinity at pH 6.0 (5.6 times strong than at pH 7.4), which mimics the hypoxic and acidic tumor microenvironment (TME). This phenomenon is not observed with marketed antibodies (Keytruda®, Opdivo®), implying that GNUV201 achieves more selective binding to and better occupancy on PD-1 in the TME. CONCLUSIONS: In summary, GNUV201 exhibited enhanced affinity for PD-1 with slow dissociation and preferential binding in TME-mimicking low pH. Human/monkey/mouse inter-species cross-reactivity of GNUV201 could enable more predictable and translatable efficacy and toxicity preclinical studies. These results suggest that GNUV201 could be an ideal antibody candidate for anti-cancer drug development.

Identification of dendritic cell precursor from the CD11c+ cells expressing high levels of MHC class II molecules in the culture of bone marrow with FLT3 ligand.

Dendritic cells (DCs) are readily generated from the culture of mouse bone marrow (BM) treated with either granulocyte macrophage-colony stimulating factor (GM-CSF) or FMS-like tyrosine kinase 3 ligand (FLT3L). CD11c+MHCII+ or CD11c+MHCIIhi cells are routinely isolated from those BM cultures and generally used as in vitro-generated DCs for a variety of experiments and therapies. Here, we examined CD11c+ cells in the BM culture with GM-CSF or FLT3L by staining with a monoclonal antibody 2A1 that is known to recognize mature or activated DCs. Most of the cells within the CD11c+MHCIIhi DC gate were 2A1+ in the BM culture with GM-CSF (GM-BM culture). In the BM culture with FLT3L (FL-BM culture), almost of all the CD11c+MHCIIhi cells were within the classical DC2 (cDC2) gate. The analysis of FL-BM culture revealed that a majority of cDC2-gated CD11c+MHCIIhi cells exhibited a 2A1-CD83-CD115+CX3CR1+ phenotype, and the others consisted of 2A1+CD83+CD115-CX3CR1- and 2A1-CD83-CD115-CX3CR1- cells. According to the antigen uptake and presentation, morphologies, and gene expression profiles, 2A1-CD83-CD115-CX3CR1- cells were immature cDC2s and 2A1+CD83+CD115-CX3CR1- cells were mature cDC2s. Unexpectedly, however, 2A1-CD83-CD115+CX3CR1+ cells, the most abundant cDC2-gated MHCIIhi cell subset in FL-BM culture, were non-DCs. Adoptive cell transfer experiments in the FL-BM culture confirmed that the cDC2-gated MHCIIhi non-DCs were precursors to cDC2s, i.e., MHCIIhi pre-cDC2s. MHCIIhi pre-cDC2s also expressed the higher level of DC-specific transcription factor Zbtb46 as similarly as immature cDC2s. Besides, MHCIIhi pre-cDC2s were generated only from pre-cDCs and common DC progenitor (CDP) cells but not from monocytes and common monocyte progenitor (cMoP) cells, verifying that MHCIIhi pre-cDC2s are close lineage to cDCs. All in all, our study identified and characterized a new cDC precursor, exhibiting a CD11c+MHCIIhiCD115+CX3CR1+ phenotype, in FL-BM culture.

Altered interictal serum histamine and immunoglobulin E but unchanged tryptase levels in individuals with episodic and chronic migraine.

BACKGROUND: Serum histamine, immunoglobulin E, and tryptase are markers of allergic diseases. Despite the reported association between migraine and allergic diseases, differences in these marker levels between episodic and chronic migraines remain unelucidated. METHODS: We investigated serum histamine, immunoglobulin E, and tryptase levels in 97 and 96 participants with episodic migraine and chronic migraine, respectively, and 56 controls according to the presence of allergic diseases. RESULTS: Serum histamine levels in episodic migraine (median and interquartile ranges, 0.78 [0.65-1.25] ng/mL, p < 0.001) and chronic migraine (0.89 [0.67-1.28] ng/mL, p < 0.001) participants were significantly lower than those in healthy controls (1.19 [0.81-2.08] ng/mL) among the 160 participants without allergic diseases. Serum immunoglobulin E levels in episodic migraine and chronic migraine participants with allergic diseases negatively correlated with headache frequency (correlation coefficient = -0.263, p = 0.017). Serum histamine levels in participants with allergic diseases and serum immunoglobulin E levels in participants without allergic diseases were not significantly different among episodic migraine, chronic migraine, and control groups. Serum tryptase levels did not significantly differ among episodic migraine, chronic migraine, and control participants with and without allergic diseases. CONCLUSIONS: Altered serum histamine and immunoglobulin E levels in episodic migraine and chronic migraine and different profiles concerning allergic diseases suggest the involvement of allergic mechanisms in migraine pathogenesis.

CTCF controls three-dimensional enhancer network underlying the inflammatory response of bone marrow-derived dendritic cells.

Dendritic cells are antigen-presenting cells orchestrating innate and adaptive immunity. The crucial role of transcription factors and histone modifications in the transcriptional regulation of dendritic cells has been extensively studied. However, it is not been well understood whether and how three-dimensional chromatin folding controls gene expression in dendritic cells. Here we demonstrate that activation of bone marrow-derived dendritic cells induces extensive reprogramming of chromatin looping as well as enhancer activity, both of which are implicated in the dynamic changes in gene expression. Interestingly, depletion of CTCF attenuates GM-CSF-mediated JAK2/STAT5 signaling, resulting in defective NF-κB activation. Moreover, CTCF is necessary for establishing NF-κB-dependent chromatin interactions and maximal expression of pro-inflammatory cytokines, which prime Th1 and Th17 cell differentiation. Collectively, our study provides mechanistic insights into how three-dimensional enhancer networks control gene expression during bone marrow-derived dendritic cells activation, and offers an integrative view of the complex activities of CTCF in the inflammatory response of bone marrow-derived dendritic cells.

No change in interictal C-reactive protein levels in individuals with episodic and chronic migraine: A case-control study and literature review.

Objectives: The levels of some migraine biomarkers differ between episodic migraine (EM) and chronic migraine (CM), but information on C-reactive protein (CRP) levels in EM and CM is conflicting. Thus, this study aimed to evaluate CRP levels in participants with EM and CM in comparison to those in healthy controls. Methods: Plasma CRP levels were evaluated by high-sensitivity CRP tests in female participants with EM (n = 174) and CM (n = 191) and healthy controls (n = 50). Results: The results showed no significant difference in CRP levels among the EM, CM, and control groups (median and interquartile range, 0.40 [0.15-0.70] mg/L vs. 0.40 [0.15-1.00] mg/L vs. 0.15 [0.15-0.90] mg/L, p = 0.991). The ratio of individuals with elevated CRP levels (>3.0 mg/L) did not significantly differ among the EM, CM, and control groups (3.4% [6/174] vs. 2.1% [4/191] vs. 0.0% [0/50], p = 0.876). Multivariable regression analyses revealed that CRP levels were not significantly associated with headache frequency per month (ß = -0.076, p = 0.238), the severity of anxiety (Generalized Anxiety Disorder-7 score, ß = 0.143, p = 0.886), and depression (Patient Health Questionnaire-9 score, ß = 0.143, p = 0.886). Further, CRP levels did not significantly differ according to clinical characteristics, fibromyalgia, medication overuse, preventive treatment, and classes of preventive treatment medications. Among participants with a body mass index ≥25 kg/m2, the CRP levels in EM (n = 41) and CM (n = 17) were numerically higher than those in the control (n = 6) (1.30 [0.28-4.25] mg/L vs. 1.10 [0.50-3.15] mg/L vs. 0.40 [0.15-0.83] mg/L, p = 0.249) but did not reach statistical significance. Conclusions: The interictal CRP level is not likely to be a biomarker for EM or CM.

PgtE Enzyme of Salmonella enterica Shares the Similar Biological Roles to Plasminogen Activator (Pla) in Interacting With DEC-205 (CD205), and Enhancing Host Dissemination and Infectivity by Yersinia pestis.

Yersinia pestis, the cause of plague, is a newly evolved Gram-negative bacterium. Through the acquisition of the plasminogen activator (Pla), Y. pestis gained the means to rapidly disseminate throughout its mammalian hosts. It was suggested that Y. pestis utilizes Pla to interact with the DEC-205 (CD205) receptor on antigen-presenting cells (APCs) to initiate host dissemination and infection. However, the evolutionary origin of Pla has not been fully elucidated. The PgtE enzyme of Salmonella enterica, involved in host dissemination, shows sequence similarity with the Y. pestis Pla. In this study, we demonstrated that both Escherichia coli K-12 and Y. pestis bacteria expressing the PgtE-protein were able to interact with primary alveolar macrophages and DEC-205-transfected CHO cells. The interaction between PgtE-expressing bacteria and DEC-205-expressing transfectants could be inhibited by the application of an anti-DEC-205 antibody. Moreover, PgtE-expressing Y. pestis partially re-gained the ability to promote host dissemination and infection. In conclusion, the DEC-205-PgtE interaction plays a role in promoting the dissemination and infection of Y. pestis, suggesting that Pla and the PgtE of S. enterica might share a common evolutionary origin.

Interictal plasma glutamate levels are elevated in individuals with episodic and chronic migraine.

Glutamate is implicated in migraine pathogenesis including central sensitization and pain transmission. Altered plasma glutamate levels has been noted in migraine. Chronic migraine (CM) presented a higher degree of central sensitization and pain transmission than episodic migraine (EM). However, no study has evaluated plasma glutamate levels separately in EM and CM. This study aimed to assess plasma glutamate levels in EM and CM compared to controls. An enzyme-linked immunosorbent assay was used to assess plasma glutamate levels in females with EM (n = 98) and CM (n = 92) as well as controls (n = 50). Plasma glutamate levels in participants with EM (median and interquartile range, 49.73 [40.82-66.12] µmol/L, p < 0.001) and CM (58.70 [44.64-72.46] µmol/L, p < 0.001) were significantly higher than those in controls (38.79 [29.50-53.60] µmol/L). Glutamate levels were not significantly different between participants with EM and CM (p = 0.075). There was no significant association of plasma glutamate levels with headache frequency (exponential and 95% confidence interval, 1.285 [0.941-1.755]) and intensity (mild, 59.95 [59.95-59.95] µmol/L vs. moderate, 52.76 [40.83-106.89] µmol/L vs. severe, 55.16 [42.34-68.03] µmol/L, p = 0.472). The plasma glutamate level is a potential indicator for EM and CM.

Interictal plasma endothelin-1 levels do not change in individuals with episodic and chronic migraine.

BACKGROUND: Individuals with migraine present ictal elevation of endothelin-1 levels. Migraine can be subclassified into episodic migraine and chronic migraine. Apart from the inconsistent reports on interictal endothelin-1 levels, most studies did not distinguish between episodic migraine and chronic migraine. METHODS: We measured plasma endothelin-1 levels in participants with episodic migraine (n = 87), with chronic migraine (n = 88), and controls (n = 50). RESULTS: Interictal endothelin-1 levels were not significantly different among participants with episodic migraine, those with chronic migraine, and controls (pg/ml, median and interquartile range, 10.19 [7.76-13.69] vs. 9.25 [6.91-10.73] vs. 9.46 [7.00-14.19], p = 0.131). After excluding participants with fibromyalgia (n = 50) and medication-overuse headache (n = 21), endothelin-1 levels were still similar among groups (10.51 [7.96-14.10] vs. 9.24 [6.96-10.81] vs. 9.46 [7.00-14.19], p = 0.230). Endothelin-1 levels did not significantly differ among participants with migraine with aura, those with migraine without aura, and controls (9.36 [4.26-13.35] vs. 9.50 [7.23-13.02] vs. 9.46 [7.00-14.19], p = 0.975). There was no significant association of endothelin-1 with headache intensity (mild, 8.99 [8.99-8.99] vs. moderate, 8.71 [6.85-12.15] vs. severe, 9.55 [7.23-13.13], p = 0.517) or headache frequency per month (exponential and 95% confidence interval, 0.709 [0.296-1.698], p = 0.440) in participants with episodic migraine and chronic migraine. CONCLUSIONS: Interictal plasma endothelin-1 level is an unlikely marker for episodic migraine and chronic migraine.

Distinct effects of different adjuvants in the mouse model of allergic airway inflammation.

BACKGROUND: Allergic asthma was typically considered as an inflammatory disease mediated by type 2 immunity. However, recent studies revealed that asthma is a complex disease displaying a variety of phenotypes and endotypes. OBJECTIVE: We examined cellular phenotypes in the mouse model of allergic asthma sensitized with different adjuvants. The aim of our study was to determine immunologic cellular characteristics in mouse asthma models induced by ovalbumin (OVA) and a variety of adjuvants. METHODS: Mice were sensitized intraperitoneally with the admixture of OVA and various adjuvants such as Alhydrogel (alum), papain, lipopolysaccharide (LPS), or CpG, and subsequently challenged with OVA intranasally. The cells in bronchoalveolar lavage (BAL) fluid, lung, and mediastinal lymph node (mLN) were examined by flow cytometric analyses. RESULTS: In the lung and BAL fluid, the highest eosinophil levels were observed in the alum group while the highest neutrophil levels were detected in the LPS group. Meanwhile, the LPS group exhibited the most elevated levels of both RORγt+ innate lymphoid cells (ILCs) and IL-17A+ Th cells in the lung and mediastinal lymph node. In the lung, the number of T-bet+ ILCs was highest in the papain group whereas the number of IFN-γ+ Th cells was highest in the CpG group. CONCLUSIONS: Notable variances are found in the composition of immune cells and expression of cytokines at the site of pathogenesis among the different mouse models of allergic asthma created by the sensitization with different adjuvants.

Corrigendum: No change in interictal C-reactive protein levels in individuals with episodic and chronic migraine: A case-control study and literature review.

[This corrects the article DOI: 10.3389/fneur.2022.1021065.].

Global Gene Expression of T Cells Is Differentially Regulated by Peritoneal Dendritic Cell Subsets in an IL-2 Dependent Manner.

Dendritic cells (DCs) in peripheral tissues may have a unique role to regulate innate and adaptive immune responses to antigens that enter the tissues. Peritoneal cavity is the body compartment surrounding various tissues and organs and housing diverse immune cells. Here, we investigated the specialized features of classical DC (cDC) subsets following the intraperitoneal injection of a model antigen ovalbumin (OVA). Peritoneal cDC1s were superior to cDC2s in activating OVA-specific CD8 T cells, while both cDCs were similar in stimulating OVA-specific CD4 T cells. Each peritoneal cDC subset differentially regulated the homing properties of CD8 T cells. CD8 T cells stimulated by cDC1s displayed a higher level of lung-homing receptor CCR4, whereas those stimulated by cDC2s prominently expressed various homing receptors including gut-homing molecules CCR9 and α4ß7. Also, we found that cDC1s played a dominating role over cDC2s in controlling the overall gene expression of CD8 T cells. Soluble factor(s) emanating from CD8 T cells stimulated by peritoneal cDC1s were responsible for mediating this dominance of cDC1s, and we identified IL-2 as a soluble factor regulating the global gene expression of T cells. Collectively, our study indicates that different peritoneal cDC subsets effectively diversify T cell responses by altering the level of cytokines, such as IL-2, in the milieu.

Loss of the virulence plasmid by Shigella sonnei promotes its interactions with CD207 and CD209 receptors.

Introduction. Shigella sonnei, the cause of bacillary dysentery, belongs to Gram-negative enteropathogenic bacteria. S. sonnei contains a 210 kb virulence plasmid that encodes an O-antigen gene cluster of LPSs. However, this virulence plasmid is frequently lost during replication. It is well-documented that after losing the O-antigen and becoming rough strains, the Gram-negative bacteria may express an LPS core on its surface. Previous studies have suggested that by using the LPS core, Gram-negative bacteria can interact with several C-type lectin receptors that are expressed on antigen-presenting cells (APCs).Hypothesis/Gap Statement. S. sonnei by losing the virulence plasmid may hijack APCs via the interactions of LPS-CD209/CD207.Aim. This study aimed to investigate if the S. sonnei rough strain, by losing the virulence plasmid, interacted with APCs that express C-type lectins of human CD207, human CD209a and mouse CD209b.Methodology. SDS-PAGE silver staining was used to examine the O-antigen expression of S. sonnei WT and its rough strain. Invasion assays and inhibition assays were used to examine the ability of S. sonnei WT and its rough strain to invade APCs and investigate whether CD209 and CD207 are receptors for phagocytosis of rough S. sonnei. Animal assays were used to observe the dissemination of S. sonnei.Results. S. sonnei did not express O-antigens after losing the virulence plasmid. The S. sonnei rough strain invades with APCs, including human dendritic cells (DCs) and mouse macrophages. CD209 and CD207 are receptors for phagocytosis of rough S. sonnei. Expression of the O-antigen reduces the ability of the S. sonnei rough strain to be disseminated to mesenteric lymph nodes and spleens.Conclusion. This work demonstrated that S. sonnei rough strains - by losing the virulence plasmid - invaded APCs through interactions with CD209 and CD207 receptors.

Granulocyte Macrophage-Colony Stimulating Factor Produces a Splenic Subset of Monocyte-Derived Dendritic Cells That Efficiently Polarize T Helper Type 2 Cells in Response to Blood-Borne Antigen.

Dendritic cells (DCs) are key antigen-presenting cells that prime naive T cells and initiate adaptive immunity. Although the genetic deficiency and transgenic overexpression of granulocyte macrophage-colony stimulating factor (GM-CSF) signaling were reported to influence the homeostasis of DCs, the in vivo development of DC subsets following injection of GM-CSF has not been analyzed in detail. Among the treatment of mice with different hematopoietic cytokines, only GM-CSF generates a distinct subset of XCR1-33D1- DCs which make up the majority of DCs in the spleen after three daily injections. These GM-CSF-induced DCs (GMiDCs) are distinguished from classical DCs (cDCs) in the spleen by their expression of CD115 and CD301b and by their superior ability to present blood-borne antigen and thus to stimulate CD4+ T cells. Unlike cDCs in the spleen, GMiDCs are exceptionally effective to polarize and expand T helper type 2 (Th2) cells and able to induce allergic sensitization in response to blood-borne antigen. Single-cell RNA sequencing analysis and adoptive cell transfer assay reveal the sequential differentiation of classical monocytes into pre-GMiDCs and GMiDCs. Interestingly, mixed bone marrow chimeric mice of Csf2rb+/+ and Csf2rb-/- demonstrate that the generation of GMiDCs necessitates the cis expression of GM-CSF receptor. Besides the spleen, GMiDCs are generated in the CCR7-independent resident DCs of the LNs and in some peripheral tissues with GM-CSF treatment. Also, small but significant numbers of GMiDCs are generated in the spleen and other tissues during chronic allergic inflammation. Collectively, our present study identifies a splenic subset of CD115hiCD301b+ GMiDCs that possess a strong capacity to promote Th2 polarization and allergic sensitization against blood-borne antigen.

Proteus mirabilis Targets Atherosclerosis Plaques in Human Coronary Arteries via DC-SIGN (CD209).

Bacterial DNAs are constantly detected in atherosclerotic plaques (APs), suggesting that a combination of chronic infection and inflammation may have roles in AP formation. A series of studies suggested that certain Gram-negative bacteria were able to interact with dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin [DC-SIGN; cluster of differentiation (CD) 209] or langerin (CD207), thereby resulting in deposition of CD209s at infection sites. We wondered if Proteus mirabilis (a member of Proteobacteria family) could interact with APs through CD209/CD207. In this study, we first demonstrated that CD209/CD207 were also receptors for P. mirabilis that mediated adherence and phagocytosis by macrophages. P. mirabilis interacted with fresh and CD209s/CD207-expressing APs cut from human coronary arteries, rather than in healthy and smooth arteries. These interactions were inhibited by addition of a ligand-mimic oligosaccharide and the coverage of the ligand, as well as by anti-CD209 antibody. Finally, the hearts from an atherosclerotic mouse model contained higher numbers of P. mirabilis than that of control mice during infection-challenging. We therefore concluded that the P. mirabilis interacts with APs in human coronary arteries via CD209s/CD207. It may be possible to slow down the progress of atherosclerosis by blocking the interactions between CD209s/CD207 and certain atherosclerosis-involved bacteria with ligand-mimic oligosaccharides.

Two Distinct Subsets Are Identified from the Peritoneal Myeloid Mononuclear Cells Expressing both CD11c and CD115.

To this date, the criteria to distinguish peritoneal macrophages and dendritic cells (DCs) are not clear. Here we delineate the subsets of myeloid mononuclear cells in the mouse peritoneal cavity. Considering phenotypical, functional, and ontogenic features, peritoneal myeloid mononuclear cells are divided into 5 subsets: large peritoneal macrophages (LPMs), small peritoneal macrophages (SPMs), DCs, and 2 MHCII+CD11c+CD115+ subpopulations (i.e., MHCII+CD11c+CD115+CD14-CD206- and MHCII+CD11c+CD115+CD14+CD206+). Among them, 2 subsets of competent Ag presenting cells are demonstrated with distinct functional characteristics, one being DCs and the other being MHCII+CD11c+CD115+CD14-CD206- cells. DCs are able to promote fully activated T cells and superior in expanding cytokine producing inflammatory T cells, whereas MHCII+CD11c+CD115+CD14-CD206- cells generate partially activated T cells and possess a greater ability to induce Treg under TGF-ß and retinoic acid conditions. While the development of DCs and MHCII+CD11c+CD115+CD14-CD206- cells are responsive to the treatment of FLT3 ligand and GM-CSF, the number of LPMs, SPMs, and MHCII+CD11c+CD115+CD14+CD206+ cells are only influenced by the injection of GM-CSF. In addition, the analysis of gene expression profiles among MHCII+ peritoneal myeloid mononuclear cells reveals that MHCII+CD11c+CD115+CD14+CD206+ cells share high similarity with SPMs, whereas MHCII+CD11c+CD115+CD14-CD206- cells are related to peritoneal DC2s. Collectively, our study identifies 2 distinct subpopulations of MHCII+CD11c+CD115+ cells, 1) MHCII+CD11c+CD115+CD14-CD206- cells closely related to peritoneal DC2s and 2) MHCII+CD11c+CD115+CD14+CD206+ cells to SPMs.

Salmonella enterica Serovar Typhimurium Interacts with CD209 Receptors To Promote Host Dissemination and Infection.

Salmonella enterica serovar Typhimurium, a Gram-negative bacterium, can cause infectious diseases ranging from gastroenteritis to systemic dissemination and infection. However, the molecular mechanisms underlying this bacterial dissemination have yet to be elucidated. A study indicated that using the lipopolysaccharide (LPS) core as a ligand, S Typhimurium was able to bind human dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (hCD209a), an HIV receptor that promotes viral dissemination by hijacking antigen-presenting cells (APCs). In this study, we showed that S Typhimurium interacted with CD209s, leading to the invasion of APCs and potentially the dissemination to regional lymph nodes, spleen, and liver in mice. Shielding of the exposed LPS core through the expression of O-antigen reduces dissemination and infection. Thus, we propose that similar to HIV, S Typhimurium may also utilize APCs via interactions with CD209s as a way to disseminate to the lymph nodes, spleen, and liver to initiate host infection.

Yersinia pestis Interacts With SIGNR1 (CD209b) for Promoting Host Dissemination and Infection.

Yersinia pestis, a Gram-negative bacterium and the etiologic agent of plague, has evolved from Yersinia pseudotuberculosis, a cause of a mild enteric disease. However, the molecular and biological mechanisms of how Y. pseudotuberculosis evolved to such a remarkably virulent pathogen, Y. pestis, are not clear. The ability to initiate a rapid bacterial dissemination is a characteristic hallmark of Y. pestis infection. A distinguishing characteristic between the two Yersinia species is that Y. pseudotuberculosis strains possess an O-antigen of lipopolysaccharide (LPS) while Y. pestis has lost the O-antigen during evolution and therefore exposes its core LPS. In this study, we showed that Y. pestis utilizes its core LPS to interact with SIGNR1 (CD209b), a C-type lectin receptor on antigen presenting cells (APCs), leading to bacterial dissemination to lymph nodes, spleen and liver, and the initiation of a systemic infection. We therefore propose that the loss of O-antigen represents a critical step in the evolution of Y. pseudotuberculosis into Y. pestis in terms of hijacking APCs, promoting bacterial dissemination and causing the plague.

In vivo targeting of protein antigens to dendritic cells using anti-DEC-205 single chain antibody improves HIV Gag specific CD4+ T cell responses protecting from airway challenge with recombinant vaccinia-gag virus.

INTRODUCTION: Targeting antigens to dendritic cells (DCs) in vivo via a DC-restricted endocytic receptor, DEC205, has been validated to enhance immunity in several vaccine platforms. Particularly atttractive is selected delivery of proteins to DCs in vivo because it enables proteins to be more immunogenic and provides a cheaper and effective way for repeated immunizations. METHODS: In this study, we tested the efficacy of a single chain antibody to DEC205 (scDEC) to deliver protein antigens selectively to DCs in vivo and to induce protective immunity. RESULTS: In comparison to soluble Ovalbumin (OVA) antigen, when recombinant scDEC:OVA protein was injected subcutaneously (s.c.) into mice, the OVA protein was selectively presented by DCs to both TCR transgenic CD8+ and CD4+ T cells approximately 500 and 100 times more efficient than soluble OVA, respectively, and could persist for seven days following s.c. injection of the scDEC205:OVA. Similarly selective targeting of HIV Gag P24 to DCs in vivo using scDEC-Gag protein plus polyICLC vaccine resulted in strong, long lasting, polyfuntional CD4+ T cells in mice which were protective against airway challenge by a recombinant vaccinia-gag virus. CONCLUSION: Thus targeting protein antigens to DCs using scDEC can be used either alone or in combination with other strategies for effective immunization.

Yersinia pseudotuberculosis Exploits CD209 Receptors for Promoting Host Dissemination and Infection.

Yersinia pseudotuberculosis is a Gram-negative enteropathogen and causes gastrointestinal infections. It disseminates from gut to mesenteric lymph nodes (MLNs), spleen, and liver of infected humans and animals. Although the molecular mechanisms for dissemination and infection are unclear, many Gram-negative enteropathogens presumably invade the small intestine via Peyer's patches to initiate dissemination. In this study, we demonstrate that Y. pseudotuberculosis utilizes its lipopolysaccharide (LPS) core to interact with CD209 receptors, leading to invasion of human dendritic cells (DCs) and murine macrophages. These Y. pseudotuberculosis-CD209 interactions result in bacterial dissemination to MLNs, spleens, and livers of both wild-type and Peyer's patch-deficient mice. The blocking of the Y. pseudotuberculosis-CD209 interactions by expression of O-antigen and with oligosaccharides reduces infectivity. Based on the well-documented studies in which HIV-CD209 interaction leads to viral dissemination, we therefore propose an infection route for Y. pseudotuberculosis where this pathogen, after penetrating the intestinal mucosal membrane, hijacks the Y. pseudotuberculosis-CD209 interaction antigen-presenting cells to reach their target destinations, MLNs, spleens, and livers.

Viperin Deficiency Promotes Polarization of Macrophages and Secretion of M1 and M2 Cytokines.

Viperin is a multifunctional protein that was first identified in human primary macrophages treated with interferon-γ and in human fibroblasts infected with human cytomegalovirus. This protein plays a role as an anti-viral protein and a regulator of cell signaling pathways or cellular metabolism when induced in a variety of cells such as fibroblasts, hepatocytes and immune cells including T cells and dendritic cells. However, the role of viperin in macrophages is unknown. Here, we show that viperin is basally expressed in murine bone marrow cells including monocytes. Its expression is maintained in bone marrow monocyte-derived macrophages (BMDMs) depending on macrophage colony-stimulating factor (M-CSF) treatment but not on granulocyte-macrophage colony-stimulating factor (GM-CSF) treatment. In wild type (WT) and viperin knockout (KO) BMDMs differentiated with M-CSF or G-MCSF, there are little differences at the gene expression levels of M1 and M2 macrophage markers such as inducible nitric oxide synthase (iNOS) and arginase-1, and cytokines such as IL-6 and IL-10, indicating that viperin expression in BMDMs does not affect the basal gene expression of macrophage markers and cytokines. However, when BMDMs are completely polarized, the levels of expression of macrophage markers and secretion of cytokines in viperin KO M1 and M2 macrophages are significantly higher than those in WT M1 and M2 macrophages. The data suggest that viperin plays a role as a regulator in polarization of macrophages and secretion of M1 and M2 cytokines.