bluuebunny/crossref_metadata_2025_split huggingface dataset:
The flavonoid galangin induces release of neutrophil extracellular traps and enhances resolution of E. coli pneumonia
Authors: dos Santos Everton OL , Mansouri Soukaina , Sekheri Meriem , El Kebir Driss , Filep Janos G 
Published: January 2023

Abstract
Killing of invading bacteria is essential for efficient control of infection and return to homeostasis. Phagocytosis of E. coli by neutrophils induces neutrophil apoptosis and subsequent efferocytosis, critical control points of the outcome of inflammation. Recently, we found that E. coli DNA impairs phagocytosis of E. coli by human neutrophils, delays neutrophil apoptosis and prolongs E. coli-evoked lung injury in mice. Here, we investigated whether the flavonoid galangin, which was shown to exert anti-inflammatory actions in several inflammation models, could also affect neutrophil function and the outcome of bacterial infection. In human neutrophils, galangin (100μM) did not affect viability or apoptosis; it efficiently countered the potent apoptosis-delaying cue from E. coli DNA by decreasing activation of ERK 1/2 and Akt, leading to Mcl-1 degradation and to collapse of mitochondrial trans-membrane potential. Galangin alone did not affect phagocytosis of live E. coli by neutrophils, and did not restore diminished phagocytosis in the presence of E. coli DNA. Consequently, phagocytosis-mediated bacterial killing was unaffected. By contrast, galangin triggered release of neutrophil extracellular traps (NETs). This was associated with enhanced bacterial killing, which was prevented in the presence of DNAse-I. In mice, galangin administered at the peak of inflammation, accelerated clearance of bacteria and the resolution of pulmonary injury evoked by intratracheal instillation of live E. coli. Collectively, these results identify novel mechanism, overriding survival cues from E. coli DNA and inducing release of NETs, by which galangin could facilitate bacterial clearance and the resolution of inflammation.
The kinetics of CCL27 expression in the skin
Authors: Davila Micha L , Xiong Na 
Published: January 2023

Abstract
The skin is exposed to a wide variety of microorganisms immediately after birth. The newly exposed skin establishes an immune ecosystem within its dermis and epidermis to promote homeostasis between the tissue and the colonizing commensal microflora. Elucidation of the mechanism by which immune cells in the skin are regulated is fundamentally important to understanding how skin homeostasis is established. We have found that the chemokine receptor CCR10 is important for the migration and function of various skin-homing lymphocytes, likely through interaction with its skin-specific ligand CCL27. However the mechanisms that regulate CCL27 expression are poorly understood. Skin sections of newborn, infant and adult mice were stained for CCL27 using a new antibody staining method to determine the kinetics of its expression. We found that CCL27 is markedly upregulated after birth, corresponding to the timeframe of increased effector and regulatory T cell migration to the skin. Further, we compared CCL27 expression in the skin of germ free and specific pathogen free mice to determine the effects of bacterial colonization. These results yield insight into the development of the skin immune system and the mechanisms by which these cells are continuously regulated.
Long term Immune Residence and Cellular Remodeling Follow Viral Infection of the Olfactory Neuroepithelial Barrier
Authors: Moseman E. Ashley , Ciesinski Alexa F. , McGavern Dorian B 
Published: January 2023

Abstract
Barrier immunity, particularly at mucosal surfaces, provides a first line of defense against invading pathogens. Unlike the more classical barrier surfaces in the gut, respiratory tract, genital tract, and skin, the olfactory epithelium within the nose is a specialized barrier structure containing layers of olfactory sensory neurons (OSNs) dedicated to our sense of smell. Because OSNs must contact the nasal airways, they are vulnerable to infection. Upper respiratory viral infection is known to damage the olfactory neuroepithelium and is associated with loss of olfaction. Neurotropic viruses, such as vesicular stomatitis virus (VSV), readily infect OSNs, yet the olfactory epithelial response to infection is unknown. Using a newly generated VSV expressing Cre recombinase, we tracked the fate of virus infected cells after clearance. Numerous cell types, including neural precursors and olfactory ensheathing cells, survived infection. In addition, several months after infection, we detected clonal patches of regenerated mature OSNs derived from previously infected neuroepithelial precursors. VSV infection drove a massive influx of CD45+ hematopoietic cells into the olfactory epithelium that established residence after viral clearance. This included antigen presenting cells and tissue resident CD4+ and CD8+ T cells that localized in and around the regenerating neuroepithelium. We postulate that these immune cells provide a barrier defense against viral rechallenge and might play a role in supporting neuronal regeneration. Collectively, these studies offer insights into how the nasal barrier remodels its neural-immune architecture to restore function and provide enhanced protection following a viral challenge.
Immune regulation in the female reproductive tract by the levonorgestrel-releasing intrauterine device during a baboon model of Chlamydia trachomatis infection
Authors: Eastman Alison J , Bergin Ingrid , Chai Daniel , Carter Kayla , Bell Jason 
Published: January 2023

Abstract
The levonorgestrel (LNG)-releasing intrauterine device (IUD) is increasing in popularity throughout the world, and is an attractive long-acting reversible contraceptive, particularly in areas of high maternal mortality. Its effects on immune responses in the female genital tract are unclear but, of note, LNG is associated with alterations in the CCL3/CCR5 axis. Chlamydia trachomatis (Ct) is the most common bacterial STI worldwide, and untreated infection can lead to infertility. Protective immune responses to Ct likely involve T cell recruitment. We hypothesized that LNG-IUS would result in decreased control of Ct infection in a baboon model. For this study, 20 baboons were randomized into the following groups: LNG-/Ct-, LNG+/Ct-, LNG-/Ct+, and LNG+/Ct+. LNG-IUS was inserted transcervically as in women, and baboons had 3 months to acclimate to the device. Baboons were inoculated with 107 IFU of serovar E Ct weekly for 5 weeks with weekly sampling of vaginal cytokines (assessed by ELISA) and Ct burden. LNG+/Ct+ baboons had delayed clearance in comparison to LNG-/Ct+ baboons (mean infection duration 10 weeks vs 3 weeks, respectively) and maintained higher bacterial burden as determined by assessed by quantitative nucleic acid amplification tests. LNG+/Ct+ baboons had lower expression of CCL3 than LNG-/Ct+ baboons during the first two weeks of infection, suggesting that the LNG-IUS altered T cell recruitment. CCL3 can be induced by IL-1β; in vitro experiments using cervical epithelium show that LNG induces less IL-1β than progesterone. We propose that LNG-IUS decreases IL-1β production in response to Ct infection, thus decreasing T cell recruitment to the infected area via the CCL3/CCR5 axis.
Identification of MAIT Cells in Human Term Decidua
Authors: Chavarria Melina , Vazquez Jessica , Stanic-Kostic Aleksandar 
Published: January 2023

Abstract
Mucosal-associated invariant T (MAIT) cells are a CD161+Vα7+ MR1-restricted T-cell subset, that has a complex relationship in regulating the microbiome and defense from invasive bacteria. Recent discovery of a placental microbiome, and genital mucosa MAIT cells, raises the possibility that MAIT are present at the maternal fetal interface and perform regulatory functions in this setting. As a first step, we analyzed human term decidua to detect MAIT cells and analyze their transcriptional programming.
Decidua was dissected from human term placentas and mononuclear cells (MCs) were isolated by mechanical (GentleMACS) and enzymatic (Collagenase V, DNAse I) disruption. MCs labeled by flurochrome-conjugated antibodies against CD3, 4, 8, 19, 27, 45RO, 161, and TCR Vα7.2 and intracellular Eomes, RORγt, and T-bet. Data was acquired on a 5 laser (355, 405, 488, 562, 633nm), 18-color BD Fortessa cytometer and analyzed with FlowJo 10.1r7.
Data revealed MAIT (CD3+CD161+Vα7.2+) cells in human term decidua, particularly of a memory CD8+ phenotype (CD27+CD45R0+), while fewer of CD4-CD8- and scant CD4+ cells were seen. Transcription factor expression analysis demonstrated uniform expression of PLZF, RORγt, and EOMES in phenotypic MAIT cells, confirming MAIT programming.
MAIT cells are present in human term decidua and add a new dimension to the immunological complex regulating the maternal-fetal interface. Mucosal immune dysregulation is implicated in pregnancy pathology, and our findings open a novel area to mechanistic investigation.
Microbiome-dependent modulation of mucosal immunity at the ocular surface.
Authors: St. Leger Anthony J , Desai Jigar V , Drummond Rebecca , Kugadas Abirami , Almaghrabi Fatimah , Silver Phyllis , Gadjeva Mihaela , Iwakura Yoichiro , Lionakis Michail S , Caspi Rachel R 
Published: January 2023

Abstract
Mucosal sites such as the intestine, oral cavity, nasopharynx, and female reproductive tract all have their associated commensal flora. The surface of the eye (conjunctiva) is also a mucosal site, but existence of a resident microbiome on the ocular surface is highly controversial. We used a mouse model of ocular surface disease to study whether commensal microbes are present in ocular mucosa and modulate immunity. We found that IL-17 is constitutively produced within the conjunctiva-associated lymphoid tissue (CALT) and recruits neutrophils to the ocular surface in the steady state and after a bacterial challenge. IL-17 sources in CALT include γδ T cells, αβ T cells and innate lymphoid cells (ILCs), in that order. Notably, a strain of Corynebacterium isolated from ocular tissue of mice, and known to occur on the ocular surface of humans, induced the conjunctival γδ T cells to secrete IL-17, which in turn modified the local inflammatory signature and barrier function. Elimination of this putative commensal by antibiotic treatment, or its introduction into non-colonized mice, correlated inversely with severity of an experimental Candida albicans infection. Our results thus indicate that a relationship exists between commensals and immune cells at the ocular surface, which is critical for maintenance of homeostasis and host defense within the ocular mucosa.
MAIT cells in the human oral mucosa are activated and perforinlow
Authors: Sobkowiak Michal , Davanian Haleh , Tjernlund Annelie , Gibbs Anna , Nayak Sushrusha , Leeansyah Edwin , Dias Joana , Heymann Robert , Krüger-Weiner Carina , Aleman Soo , Moll Markus , Sällberg-Chen Margaret , Sandberg Johan K 
Published: January 2023

Abstract
Mucosa-associated invariant T (MAIT) cells are a class of non-classical T lymphocytes defined by their invariant Vα7.2-containing MR1-restricted T cell receptor, as well as high expression of CD161. At present, the characteristics of MAIT cells in the oral mucosa are poorly defined. In this study, we have analyzed buccal biopsies and matched blood samples from a cohort of healthy volunteers. MAIT cells were present in the buccal mucosa, with a tendency to cluster around the basal layer, a region also found to contain a higher frequency of MR1-expressing antigen-presenting cells. The frequency of MAIT cells was similar in the buccal mucosa compared to matched peripheral blood, in contrast to other major T cell subsets. However, the buccal mucosal MAIT cells displayed a tissue resident activated profile, with high CD69, HLA-DR and PD-1 expression, as well as a skewed subset distribution with higher representation of CD4/CD8 double-negative cells and of CD8αα+ cells within the CD8+ subset. The Jα chain usage in the MAIT cell TCR was more variable in oral mucosal MAIT cells than in peripheral blood MAIT cells. Functionally, the oral mucosal MAIT cells had lower perforin levels, indicative of a lower cytolytic potential. Interestingly, aspects of the oral MAIT cell population were associated with life-style factors such as consumption of bacterially fermented milk products and alcohol intake. Together, these data show that MAIT cells form a part of the oral mucosal T cell compartment, where they exhibit a tissue-resident activated profile. Thus, MAIT cells are positioned in the oral cavity and equipped to handle resident microbiota as well as invading pathogens.
Modulation of CD4+ T cell polarization using non-canonical co-receptors
Authors: Meeks Christian Matthew , Horton Christopher G 
Published: January 2023

Abstract
CD4+ T helper cells are a diverse group of cells promoting target cell death and production of antibodies. These cells acquire one of several fates following signals through the T cell receptor, co-receptors, and cytokines. The cytokine requirements inducing the polarization of T cell fate has been heavily evaluated and reasonably well defined. However, the influence provided by co-receptors has not been completely elucidated. Traditionally, in vitro T cell polarization assays utilize CD28 stimulation as the primary co-receptor signal required for differentiation. Others have observed the importance of supplementary co-receptors in activation of T helper cells, though little is known about their function in early stage polarization. We hypothesized that the addition of signaling through supplemental co-receptors would alter T helper cell polarization. To conduct these studies, we isolated naïve T cells and polarized them towards Th1 or Tfh fates in the presence or absence of recombinant B7-DC Fc chimera or recombinant B7-H4 Fc chimera. We observed a significant and selective alteration in T helper cell polarization in the presence of these non-canonical co-receptors. These data suggest a complex interplay between cytokine and co-receptor signals that cooperate for robust Th cell polarization. Furthermore, these findings illustrate the potential for novel mechanisms of T cell manipulation for vaccine design and treatment of T cell-mediated diseases.
STAT1 is required for Tfh lineage maintenance through regulation of IL-21 expression
Authors: Nurieva Roza I , Sahoo Anupama , Alekseev Andrei 
Published: January 2023

Abstract
T follicular helper (Tfh) cells are a specialized subset of T helper cells necessary for germinal center reaction, affinity maturation, and the differentiation of germinal center B cells to antibody-producing plasma B cells and memory B cells. The differentiation of Tfh cells is a multistage, multifactorial process involving a variety of cytokines, surface molecules and transcription factors. While to date early signaling events for fate committed differentiation of Tfh cells are sufficiently studied, mechanisms allowing Tfh cells to maintain their commitment/programming are still unclear. Here we report that STAT1 deficiency in CD4+ T cells leads to diminished number of Tfh cells at day 7 and 14 days after antigen immunization, while at day 3–4, number of Tfh cell were comparable between STAT1-sufficient and STAT1-deficient mice, suggesting the role of STAT1 in Tfh lineage maintenance rather than in Tfh cell priming. Interestingly STAT 1 deficiency in both mouse and human Tfh cells leads to significant drop in IL-21 expression, while the expression of Tfh-specific genes such as Bcl6, CXCR5 and c-Maf was not affected. Functionally, STAT1 in cooperation with STAT3 triggers IL-21 production in Tfh cells by directly binding to and activation of the IL-21 gene locus. In addition, STAT1/STAT3 cooperation influences the expression of transcriptional factor Batf as well as determines Batf-driven IL-21 expression in Tfh cells. Our results thus indicate STAT1 dependent mechanism for IL-21 expression and Tfh lineage maturation and maintenance.
IL2 production predicts Tfh differentiation
Authors: DiToro Daniel F , Winstead Colleen J , Andargachew Rakieb , Zindl Carlene , Moseley Carson Edward , Pham Duy , Evavold Brian D , Weaver Casey Todd 
Published: January 2023

Abstract
Naïve CD4 T cells differentiate into functionally distinct subsets in response to a set of extrinsic and intrinsic cues. Effector subsets, including Th1, Th2 and Th17 CD4s, are required for optimal cellular responses to invading pathogens, while class switched antibody responses depend on the differentiation of T follicular helper cells (Tfh). Development of both Tfh and non-Tfh occurs in parallel and involves two distinct but functionally related expression bifurcations. Upon formation of T cell receptor (TCR)/major histocompatibility (MHC) synapses with antigen-presenting cells (APC), a discrete subset of activated T cells secretes the cytokine IL2. Similarly, a portion of activated cells express the transcription factor Bcl6 and differentiate into Tfh cells, while the remainder express Blimp1 and develop into effector CD4s. However, the cellular, temporal and mechanistic relationships between these two bifurcations remain unclear. Here we show that the IL2 and Bcl6/Blimp1 expression bifurcations occur simultaneously, precede cell division, predict differentiation into Tfh and non-Tfh subsets, and are mechanistically related to antigen availability TCR density.
Characterization of memory CD4+ T cells in skin following infection
Authors: Collins Nicholas , Gebhardt Thomas , Carbone Francis R 
Published: January 2023

Abstract
Following elimination of virus, stable populations of memory T cells that rapidly respond to secondary infection are generated. A substantial proportion of the memory T cells in the body are found within barrier tissues such as the skin. It remains unclear to what extent the cells in these compartments exchange with those in circulation versus the proportion remaining permanently resident within the tissues. We have examined this for CD4+ T cells in mouse skin. Using parabiosis, we have found that the majority of CD4+ T cells in skin at steady-state are in equilibrium with the blood. A relatively small proportion of skin CD4+ T cells persist in skin for several months without returning to the circulation. At memory following localized infection with HSV-1 or following treatment with the sensitizing agent DNFB, the number of CD4+ T cells in skin does not return to the naïve or baseline levels. Rather, the number of CD4+ T cells in the affected region remains stable over time at a level 6–8 fold higher than in unaffected skin from the same mice. This increase in CD4+T cell numbers is a consequence of enhanced recruitment from the blood and/or prolonged persistence of recruited circulating T cells once in skin before again returning to the circulation. Hair follicle-derived chemokines are involved in retaining CD4+ memory T cells in skin and the majority of CD4+ T cells that produce IFNg in response to secondary HSV-1 infection show perifollicular localization. Overall, this characterization of the CD4+ T cell content in skin following infection and contact sensitization provides an insight into how these cells are retained in skin for enhanced response on subsequent antigen encounter.
Natural killer cells modulate B-cell affinity maturation in an antigen dose-dependent manner
Authors: Rydyznski Carolyn E. , Cranert Stacey A , Waggoner Stephen N 
Published: January 2023

Abstract
Affinity maturation via somatic hypermutation (SHM) in germinal centers (GC) is crucial for development of protective humoral immunity. Our discovery that natural killer (NK) cells potently inhibit GC expansion highlights a novel target for improving humoral responses during vaccination. We hypothesized that enhanced GCs in the absence of NK cells would promote increased affinity maturation via SHM. Using the immunogen, NP-KLH, we show that depletion of NK cells (ΔNK) prior to immunization results in higher numbers of follicular helper T (Tfh), GC B, and NP-specific IgG1+ B cells. Sera titers of NP-specific IgG and IgG1 were also elevated in ΔNK mice compared to controls. Unexpectedly, B-cell receptor (BCR) sequencing of NP-specific GC B-cell clones revealed a marked reduction in the total number of BCR mutations in B cells from ΔNK mice at 2 to 4 weeks post-immunization. This appeared to be independent of the generation of the affinity-increasing W33L mutation. We speculated that the increase in Tfh and GC B cell numbers may exceed antigen availability to fuel continued SHM. Thus, we gave a second dose of NP-KLH a week after the first injection. Tfh and GC B cells were still increased in ΔNK mice following a second dose. Yet in striking contrast to the extent of SHM following one dose, re-injection of antigen promoted a roughly two-fold increase in both the total number of mutations and the proportion of clones bearing the W33L mutation when NK cells were absent. These exciting results suggest that NK cells restrict the magnitude of GCs and qualitatively shape the humoral response via antigen dose-dependent effects on SHM. Thus, NK cells are a previously overlooked means of humoral regulation that might be modulated to improve vaccine responses.
Stimulation through innate immune receptors selectively upregulates co-receptor expression on B cells
Authors: Dhoonmoon Ashna , Horton Christopher G 
Published: January 2023

Abstract
T lymphocytes require two signals for appropriate activation – signal one is obtained via antigen presentation to the T cell receptor and signal two is provided by a co-receptor. In the absence of signal two, T cells remain unresponsive, thus these accessory proteins serve an essential purpose in an immune response. Co-receptors include two primary classes: co-stimulatory molecules and co-inhibitory molecules. Co-stimulatory molecules including CD80 and CD86, interact with CD28 to promote T cell proliferation and survival, while co-inhibitory molecules such as B7-DC, B7-H3 and B7-H4 limit the strength and duration of immune responses. In addition to orchestrating an immune response against pathogens, co-receptors have also been implicated in several diseases. Numerous studies have revealed abundant expression of inhibitory co-receptors in tumor microenvironments, contributing to tumor immunosuppression. Furthermore, lack of inhibitory signals in mouse models leads to lupus-like autoimmunity. While the rudimentary functions of these receptors are somewhat clear, the contexts in which they are expressed are incompletely understood. In this study, we aimed to fill this knowledge gap by investigating the effects of innate immune stimuli on expression of B7-family co-receptors. Our data demonstrate that stimulation of mouse splenocytes with synthetic Toll-like receptor agonists leads to selective alterations in co-receptor expression, most notably among B lymphocytes. These data suggest an avenue by which detection of conserved microbial motifs may modulate adaptive immunity through regulation of co-receptor expression on antigen presenting cells.