bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neutrophil responses to acute Mycobacterium tuberculosis infection in non-human primates
Authors: Phuah Jia Yao , Junecko Beth , Mattila Joshua T. 
Published: January 2023

Abstract
In human and animal models of Mycobacterium tuberculosis (Mtb) infection, neutrophil involvement is associated with severe active disease and increased tissue pathology in tuberculosis (TB). Transcriptomic analyses of human and non-human primate peripheral blood has identified distinct transcriptional signatures, especially during early stages of infection, that link neutrophils and active disease but the biology of peripheral blood neutrophils in TB remains poorly understood. This study is aimed at understanding neutrophil behavior during early stages of Mtb infection using the non-human primate model of TB infection. To accomplish this, we examined cytokine production, secretion, and gene transcription in cynomolgus macaque peripheral blood neutrophils early after Mtb infection. We found that peripheral blood neutrophils could secrete a surprising range of cytokines in response to mycobacterial stimulation, and in a longitudinal analyses, cytokine expression was upregulated between 3-5 weeks post Mtb infection. Studies on neutrophil transcriptional responses to Mtb were performed to identify changes induced by mycobacterial antigens. These results suggest that changes in host biology during early disease modify peripheral blood neutrophil responses to mycobacteria.
Balance of IL-21 and type I IFN in the granzyme-dependent innate immune response to Staphylococcus aureus
Authors: Spolski Rosanne , West Erin , Li Peng , Kazemian Majid , Leonard Warren J. 
Published: January 2023

Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) infection is a major complication of viral respiratory infections and immunodeficient states. Here, we investigated the role of interleukin-21 (IL-21) in host response to pulmonary MRSA infection and unexpectedly found that IL-21 acts directly on neutrophils and can promote MRSA clearance. When administered intra-tracheally into wild-type mice, IL-21 potently induced granzymes and augmented host defense, and IL-21-induced killing of MRSA was also observed with peripheral blood neutrophils from healthy donors but not from patients with autosomal dominant hyper-IgE (Jobs) syndrome. Unexpectedly, however, loss of IL-21 signaling, as occurs in Il21r KO mice or WT mice treated with an IL-21R-Fc fusion protein or mice expressing a mutant STAT3 transgene, also resulted in enhanced clearance of MRSA, and this was associated with enhanced expression of interferon-dependent genes. Moreover, IFNb induced granzyme B expression by neutrophils, and a granzyme B inhibitor blocked IFNb-induced MRSA clearance. These results reveal a balance and an interplay between IL-21 and type-I IFN signaling in the granzyme-dependent neutrophil response to MRSA, indicating that manipulating IL-21 signaling may be a strategy for controlling pulmonary bacterial infections.
Addition of apoptotic cells alters immune cell function and reduces ankle swelling in experimental Lyme arthritis
Authors: Hilliard Kinsey A. , Brown Charles R. 
Published: January 2023

Abstract
Experimental Lyme arthritis is induced by the infection of C3H mice with the spirochete, Borrelia burgdorferi, (Bb), and is a valuable model to study the regulation of inflammation during bacterial infection. We are interested in understanding the role that apoptotic cells (AC) play in inflammation resolution during murine Lyme arthritis. We show the number of AC within infected ankle joints significantly increases during arthritis resolution. Additionally, injection of AC into the tibio-tarsal joints of Bb infected mice reduces ankle swelling compared to control animals. In vitro studies using bone marrow derived macrophages (BMDM) co-cultured with Bb demonstrates the addition of AC decreases TNFα and KC production, while increasing IL-10 and PGE2 levels. The presence of AC in BMDM and also bone marrow neutrophils (BMN) cultures, decreases Bb phagocytosis, and also decreases BMN migration to LTB4. To further explore this mechanism, we measured expression of PPAR-γ (peroxisome proliferator-activated receptor gamma), which is known to regulate cytokine expression. Addition of AC to BMDM/Bb co-cultures increased PPAR-γ transcription in vitro, and also within infected ankle joints compared to mock treated mice in vivo. We also found AC themselves can produce PGE2, a bioactive lipid which activates PPAR-γ, setting up a positive feedback loop for the production PGE2. These results suggest AC can alter macrophage and neutrophil effector functions and may play a role in downregulating inflammatory responses, perhaps via activation of PPAR-γ. In addition, injection of AC into infected joints may limit inflammatory responses or induce their resolution.
Interferon-Independent Protection by Interferon Regulatory Factor 3
Authors: Gyorke Clare Elise , Nagarajan Uma 
Published: January 2023

Abstract

BACKGROUND
Independent type I/III IFN regulation, interferon-regulatory factor 3 (IRF3) can mediate cell death and suppress proliferation during stress. Novel ‘suicide necrosis’ centers around IRF3 and is one protective mechanism against intracellular pathogens. Uterine epithelial cells infected with obligate intracellular Chlamydia trachomatis are typically shed 3–5 days post-infection (dpi) by unknown mechanism(s) and exhibit new growth. We have previously shown IRF3-deficient mice exhibit decreased epithelial shedding and 10-fold greater bacterial burdens during early infection. We hypothesize that IRF3-mediated cell death restricts chlamydial infection in the genital mucosa, providing a potentially novel mechanism to reduce pathogen load.

METHODS
Progesterone-treated C57BL/6J and IRF3 KO mice were infected vaginally with 3e5 IFUs of C. muridarum strain “Nigg” and histologically assessed 3 and 4 dpi for chlamydia inclusions, cell death and proliferation using proliferation marker PCNA. Cell death was assessed in vivo with PI delivery by NSET device 10 minutes before sacrifice 4 dpi.

RESULTS/CONCL
3 dpi, uterine epithelia in WT and IRF3 KO mice remain intact with no epithelial shedding. WT show a single layer of infected epithelial cells, while IRF3 KO have several layers of infected cells, suggesting the next layer(s) of epithelial cells are generated before the first is shed. 4 dpi we see dramatic increases in epithelial shedding in WT mice when stained in vivo with PI. In contrast, IRF3 KO epithelia show relatively few PI-stained cells. We conclude that IRF3 is playing a significant and protective role during C. muridarum infection by facilitating cell death and limiting cellular proliferation of epithelial cells.
CXCL-1/KC collaborates with CXCL-2/MIP2 to regulate granulopoiesis and recruitment in pneumococcal pneumonia
Authors: Paudel Sagar , Baral Pankaj , Bergeron Scott R. , Ghimire Laxman , Jin Liliang , DeCorte Joseph A. , Le John T. , Cai Shanshan , Jeyaseelan Samithamby 
Published: January 2023

Abstract
Streptococcus pneumoniae remains as a leading cause of community-acquired pneumonia in the U.S. and world. Leukocytes (neutrophils) recruitment to the lungs is critical step in the host defense against pneumococcal infections. CXCL-1/KC is sufficient to induce neutrophil influx in numerous bacterial lung infections, but precise mechanism of how it regulates recruitment to the lungs remains unexplored. Here, we used a mouse model of pneumococcal pneumonia to investigate the role of CXCL-1 in neutrophil granulopoiesis, recruitment, and host defense. CXCL-1 knockout and their wild type controls were infected intratracheally with S. pneumoniae. Survival, leukocyte influx, cytokines/chemokines in bronchoalveolar lavage fluid, and bacterial burdens in lungs and other organs were quantified. Flow cytometry was performed to study different stages of neutrophil granulopoiesis according to their levels of c-Kit and Ly6G expression. Recombinant CXCL-2/MIP2 was administered to rescue neutrophil recruitment in CXCL-1 knockout mice. We here demonstrate that CXCL-1 modulates rapid neutrophil influx, restricts bacterial burden in lungs, regulates production of cytokines/chemokines, and improves host survival. Flow cytometry analysis revealed CXCL-1 is involved in efficient amplification of early neutrophil precursor and release of mature neutrophils from bone marrow. Furthermore, CXCL-2 treatment post-pneumonia corrected the impairment in host defense through increased neutrophil influx in CXCL -1 knockout mice. These results suggest CXCL-1 mediates granulopoiesis and recruitment of neutrophil, and modulation of its activity presents a promising avenue for development of therapeutics against pneumococcal pneumonia.
Investigating the antibacterial effect of Sca1+ lung mesenchymal stem cells on multidrug resistant bacterial species
Authors: Rangasamy Tirumalai , Paudel Sagar , Ghimire Laxman , Jin Liliang , Bergeron Scott R. , Jeyaseelan Samithamby 
Published: January 2023

Abstract

Rationale
Although bone marrow-derived mesenchymal stem cells have been extensively studied in host protection against bacterial pneumonia, the role of lung stem/mesenchymal stem cells in pneumonia caused by the multidrug-resistant bacteria remains elusive.

Methods
We have compared the extracellular (using 10 MOI) and intracellular (using 1 MOI) killing effects of stem cell antigen 1+ lung mesenchymal stem cells (Sca1+ LMSC), bone marrow-derived neutrophils (BMDN), and bone marrow-derived macrophages (BMDM) by infecting them with Gram positive methicillin-resistant Staphylococcus aureus (MRSA) and Gram negative carbapenem-resistant Klebsiella pneumoniae (CRKP) at different time points. We evaluated the extracellular and intracellular killing at each time point by plating them on Tryptic soy agar and MacConkey agar plates, respectively. We also have examined expression of inflammasomes or inflammasome-associated proteins in MRSA (20 MOI for 6 h) infected LMSC using Western blotting.

Results
Sca1+ LMSC is potent in killing (extracellular) both MRSA and CRKP at 3 h post-infection. However, BMDN did not show significant extracellular killing on MRSA and CRKP at all time points examined. Interestingly, Sca1+ LMSC showed a remarkably increased intracellular killing of MRSA than BMDM. Western blotting revealed the increased level of inflammasome and inflammasome-associated proteins (NLRP3, NLRP6 and ASC) in MRSA infected LMSC.

Conclusions
These findings have solidified the potential of LMSC-based therapies for pneumonia caused by MRSA and CRKP. However, in vivo (animal) studies are required to determine the effectiveness of LMSC in the clearance of these bacteria and modulation of innate immune responses in the host.
CXCL5 suppresses IL-17A mediated immunity during MRSA-induced pneumonia
Authors: Ghimire Laxman , Bergeron Scott R. , Paudel Sagar , Jeyaseelan Samithamby 
Published: January 2023

Abstract
Lipopolysaccharides induced CXC-chemokine (LIX or CXCL5) is a potent chemoattractant for neutrophil recruitment to the lung during acute bacterial infections. However, its role in MRSA-induced pneumonia has not been established. We used C57BL/6 (wild-type) and CXCL5 knockout (KO) mice to induce pneumonia by intratracheal inoculation of 5×107 colony forming units (CFUs) of MRSA per mouse. Mice were sacrificed at 12 and 24 hours post-infection to enumerate bacterial burden, determine cellular recruitment, and perform cytokine analysis. Flow cytometric analysis of lungs cells was performed to determine the source of IL-17A. Unlike their wild-type counterparts, KO mice were protected from MRSA-induced pneumonia having significantly higher survival and less bacterial burden in lung and BALF. Total leukocytes and neutrophil recruitment into the airspaces was significantly higher in KO mice. However, proinflammatory cytokines, such as IL-1β, IL-6, and TNF-α were significantly higher in WT mice compared to that of KO mice. In contrast, IL-17A was significantly higher in KO mice. Blocking of IL-17A in the KO mice increased the bacterial burden in the lungs and BALF. In addition, pre-treatment of neutrophils with recombinant IL-17A significantly enhanced ROS production and killing ability of neutrophils in response to MRSA infection. Neutrophils and γδ-T cells were major sources of IL-17A during pulmonary MRSA infection. Together, our findings demonstrate that CXCL5 negatively regulates γδ-T cells and neutrophils driven IL-17A-mediated immunity during MRSA-induced pneumonia and blocking CXCL5 could be a potential therapeutic approach to treat MRSA-infected pneumonic patients.
The oxidized phospholipid oxPAPC ameliorates septic shock by targeting the non-canonical inflammasome in macrophages
Authors: CHU LAN H. , Indramohan Mohanalaxmi , Ratsimandresy Rojo A. , Gangopadhyay Ạnu , Morris Emily P. , Monack Denise M. , Dorfleutner Andrea , Stehlik Christian 
Published: January 2023

Abstract
Inflammasomes are signaling complexes that link the recognition of pathogen and danger associated molecular patterns (PAMPs and DAMPs) by cytosolic pattern-recognition receptors (PPRs) to the activation of Caspase-1, leading to the release of the pro-inflammatory cytokines interleukin (IL)-1β and IL-18, and the induction of pyroptosis. In addition to the canonical inflammasome activation by Caspase-1, other inflammatory caspases including murine Caspase-11 and its human orthologs Caspase-4 and Caspase-5 participate in the non-canonical pathway in response to intracellular LPS and Gram negative bacteria escaping the phagosomes, resulting in pyroptotic cell death as well as NLRP3 inflammasome-dependent cytokine release. Contrary to the highly regulated multiprotein platform required for Caspase-1 activation in the canonical inflammasomes, non-canonical inflammatory caspases are directly activated by binding to LPS thus simultaneously act as innate sensors and effectors. It is still largely unknown how the activity of these caspases is regulated. Here we identified the oxidized phospholipid 1-Palmitoyl-2-arachidonoyl-sn- glycero-3-phosphorylcholine (oxPAPC) as a negative regulator of the non-canonical inflammasome in macrophages. In addition to its previously reported TLR4 antagonistic role, oxPAPC directly binds to Caspase-4 and Caspase-11, competes with LPS binding and consequently, inhibits LPS-induced pyroptosis, IL-1β release and septic shock in vivo. Therefore, oxPAPC and its derivatives could provide a basis for novel therapies targeting non-canonical inflammasomes during Gram-negative bacterial sepsis.
TCF/LEF family transcription factors in peripheral Treg homeostasis
Authors: Fu Wenxian , Yang Bi-Huei , Yuan Xiaomei , Dong Yi 
Published: January 2023

Abstract
CD4+Foxp3+ regulatory T cells (Tregs) are key players in preventing lethal autoimmunity and excessive inflammation. However, the homeostatic dynamics of Tregs in peripheral lymphoid and non-lymphoid tissues remains poorly defined. We here report that two TCF/LEF family transcription factors, LEF1 and TCF1, play critical roles in this process. Our studies led to a revised “three-stage” model of Treg peripheral differentiation, delineated by the gradient expressions of LEF1 and TCF1. We found that LEF1− TCF1− subset was bona fide effector Tregs and exhibited a core gene signature shared by various tissue Tregs. Transcriptome and conditional knockout analyses revealed that TCF1 and LEF1 may each control segregated clusters of Treg genes and regulate Treg differentiation in a “division of labor” manner. Together, these data provide novel insights into transcriptional regulation of Treg homeostasis and function.
The TCR/ITK signaling pathway regulates the counterbalance of effector and regulatory T cell development
Authors: Huang Weishan , August Avery 
Published: January 2023

Abstract
The mammalian immune system has evolved both effector and regulatory immune axes, and T cells are the key players in both arms. The immune system sorts, responds to and clears invading pathogens through pro-inflammatory activity, which can cause damage to the affected tissues, and eventually have to be resolved to allow tissue remodeling and resume physiological homeostasis. The balance between pro-inflammatory and suppressive immune functions are critical for host health and survival. The T cell antigen receptor (TCR) signals through the downstream non-receptor interleukin-2 inducible T cell kinase (ITK), which is a key signaling modulator of T cell development, differentiation, activation and function. We find that in the face of different inflammatory and nutritional conditions, the TCR/ITK signaling pathway fine-tunes the balance between effector and regulatory T cell development, such as the ratio between Th17/Treg and Th1/Tr1 cells. This balance is regulated by the TCR/ITK signaling via differential downstream signals and metabolic programs. While ITK is not required for T cell activation, it functions as a rheostat of the TCR to regulate signal strength in response to extracellular antigens, and may be a target to allow therapeutically manipulating the balance between effector and regulatory immunity, dependent on the disease conditions.
Vagotomy decreases splenocytes and MHCII+/CD11B+ cells in the spleen
Authors: Nazarali Rizwan , Shapiro Lee A. , Mukherjee Sanjib 
Published: January 2023

Abstract
The Vagus Nerve is a major component, in conjunction with the spleen, in modulating the systemic anti-inflammatory response.
Adrenergic fibers of the splenic nerve innervate the spleen, where they stimulate a distinct population of memory T cells. These memory T cells subsequently release ACh, thereby reducing macrophage activation and inhibiting TNFα. Therefore this pathway, as it relates to the spleen, is a two-neuron circuit: initiating first in the dorsal motor nucleus of the Vagus, subsequently synapsing at the celiac ganglion, and finally synapsing on the memory T cells.
There are additional lines of evidence demonstrating cholinergic modulation of immune cells in the spleen. For example emerging evidence supports a regulating role of the vagus nerve in mobilizing marginal zone B cells and their subsequent secretion of antibodies, heralding an innate immune response. However, a direct link between splenic B cell number and the vagus nerve has not been previously established. Therefore, we assessed the effects of a left unilateral vagotomy on total splenocytes and MHCII+/CD11+ B cells in the spleen 3 days after vagotomy.

Results
The results indicate that at 3 days after left unilateral vagotomy, there is a significant decrease in the overall number of splenocytes. The results also show that this vagotomy results in a trend toward a significant reduction in MHCII+/CD11+ B cells in the spleen.

Conclusions
Our conclusions based upon these results show that there is a direct influence of left vagus nerve innervation on the number of splenic B cells and that left vagotomy results in an overall decrease in either the proliferation of splenocytes in general including the B-cells, or in cell death of splenocytes including the B cells.
Cytokine regulation in human CD4 T cells by the Aryl Hydrocarbon Receptor and GPR68
Authors: McAleer Jeremy P. , Fan Jun , Roar Bryanna , Primerano Donald A. , Denvir James 
Published: January 2023

Abstract
Th17 cells contribute to host defense on mucosal surfaces but also provoke autoimmune diseases when directed against self-antigens. Identifying therapeutic targets that regulate Th17 cell differentiation and/or cytokine production has considerable value. Here, we study the aryl hydrocarbon receptor (AhR)-dependent transcriptome in human CD4 T cells treated with Th17-inducing cytokines. We show that the AhR reciprocally regulates IL-17 and IL-22 production in human CD4 T cells. Global gene expression analysis revealed that AhR ligation decreased IL21 expression, correlating with delayed upregulation of RORC during culture with Th17-inducing cytokines. We further show that expression of GPR15, GPR55 and GPR68 positively correlates with IL-22 production in the presence of the AhR agonist FICZ. Activation of GPR68 with the lorazepam-derivative ogerin resulted in suppression of IL-22 and IL-10 secretion by T cells, with no effect on IL-17. These data reveal a novel feedback inhibitory pathway on IL-22 and IL-10 production in the presence of AhR agonists.
Dynamic changes in Mycobacterium tuberculosis-induced granulomas: developing new tools
Authors: Marcus Sarah Ann , Herbath Melinda , Fabry Zsuzsanna , Sandor Matyas 
Published: January 2023

Abstract
Continuous cell replacement has been demonstrated in a transplantation model of BCG infected liver, however, the Mtb lung granuloma has yet to be studied as lung tissue is not amenable to granuloma transplantation. To demonstrate the plasticity of Mtb lung granulomas, we treated mice 6 weeks post infection with chemokine inhibitors for 7 days. Treated lungs showed a strong, significant reduction in granuloma size, which suggests continuous cell replacement and indicates that Mtb granulomas are actively maintained during infection.
To examine cell fate in more detail, we utilized STOCK Tg(CAG-KikGR)33Hadj/J mice to photo-tag lung granulomas in situ. Following exposure to 405 nm light KikGR Red (583/593 nm) photoconverted lung regions or cells could be differentiated from unexposed Green (507/517 nm) systemic cells. These mice were aerosol infected with 200 CFU Mtb H37Rv. Portions of infected lungs were photoconverted 4 wpi, harvested up to 7 days post-exposure, and examined, along with mediastinal lymph nodes, by confocal microscopy.
Areas of photoconversion were successfully identified in infected lungs. F4/80+ macrophages and CD4+ T-cells were stained and screened for red versus green fluorescence. Unconverted cells of both types were found, demonstrating the utility of this technique for detecting influx into the granuloma. Efflux of cells from the granuloma was also confirmed by the detection of photoconverted cells within the unconverted MLNs. While further optimization is necessary to use this model for quantitative analysis, these results implicate continuous cell recruitment into granulomatous lesions. Elucidating cell traffic to granulomas with this technique can lead to new therapies for many granulomatous diseases.