Frontiers in Cellular and Infection Microbiology
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2235-2988

Author(s):  
Rei-Hsing Hu ◽  
Chia-Ta Wu ◽  
Ting-Shuan Wu ◽  
Feng-Yih Yu ◽  
Jiunn-Liang Ko ◽  
...  

BackgroundAllergic asthma, a chronic airway inflammatory disease, is a critical public health problem. Indoor house dust mites (HDMs) could cause allergic asthma. The prevalence of sensitization to Dermatophagoides microceras (Der m) was approximately 80% and is related to the immunoglobulin E crossing-reactivity of mites belonging to the same genus, Dermatophagoides pteronyssinus (Der p) and Dermatophagoides farina (Der f). However, studies on Der m are scant.MethodsWe used integrated OMICs approaches to identify and characterize the group 2 mite allergen-like protein in Der m (Der m 2). We established a Der m 2-induced allergic asthma mouse model and treated the mice with a fungal immunomodulatory protein (FIP-fve) isolated from Flammulina veluptipes to evaluate the allergenicity of Der m 2 and the immunomodulatory effects of FIP-fve.ResultsBy performing de novo draft genome assembly and comparative genome analysis, we identified the putative 144-amino acid Der m 2 in silico and further confirmed its existence through liquid chromatography–tandem mass spectrometry. Der m 2 is a lipopolysaccharides (LPS)-binding protein. Thus, we examined the LPS-binding activity of recombinant Der m 2 by performing molecular docking analysis, co-immunoprecipitation (Co-IP), and a pull-down assay. Der m 2 elicited the production of pro-inflammatory cytokines, interleukin (IL)-6, and IL-8 in BEAS-2B cells, a human bronchial epithelial cell line, and induced airway hyperresponsiveness in mice. Furthermore, in mice sensitized with Der m 2, the administration of FIP-fve in either the earlier stage or the late stage, FIP-fve alleviated allergic asthma by moderating airway inflammation and remodeling.ConclusionsDer m 2 induced inflammatory responses in cell and mouse models. FIP-fve alleviated inflammation in Der m 2-induced asthma in mice by exerting an immunomodulatory effect.


Author(s):  
Laura Willen ◽  
Esra Ekinci ◽  
Lize Cuypers ◽  
Heidi Theeten ◽  
Stefanie Desmet

Streptococcus pneumoniae is an important and frequently carried respiratory pathogen that has the potential to cause serious invasive diseases, such as pneumonia, meningitis, and sepsis. Young children and older adults are among the most vulnerable to developing serious disease. With the arrival of the COVID-19 pandemic and the concomitant restrictive measures, invasive disease cases caused by respiratory bacterial species, including pneumococci, decreased substantially. Notably, the stringency of the containment measures as well as the visible reduction in the movement of people appeared to coincide with the drop in invasive disease cases. One could argue that wearing protective masks and adhering to social distancing guidelines to halt the spread of the SARS-CoV-2 virus, also led to a reduction in the person-to-person transmission of respiratory bacterial species. Although plausible, this conjecture is challenged by novel data obtained from our nasopharyngeal carriage study which is performed yearly in healthy daycare center attending children. A sustained and high pneumococcal carriage rate was observed amid periods of stringent restrictive measures. This finding prompts us to revisit the connection between nasopharyngeal colonization and invasion and invites us to look closer at the nasopharyngeal microbiome as a whole.


Author(s):  
Elizabeth K. K. Glennon ◽  
Tinotenda Tongogara ◽  
Veronica I. Primavera ◽  
Sophia M. Reeder ◽  
Ling Wei ◽  
...  

Upon transmission to the human host, Plasmodium sporozoites exit the skin, are taken up by the blood stream, and then travel to the liver where they infect and significantly modify a single hepatocyte. Low infection rates within the liver have made proteomic studies of infected hepatocytes challenging, particularly in vivo, and existing studies have been largely unable to consider how protein and phosphoprotein differences are altered at different spatial locations within the heterogeneous liver. Using digital spatial profiling, we characterized changes in host signaling during Plasmodium yoelii infection in vivo without disrupting the liver tissue. Moreover, we measured alterations in protein expression around infected hepatocytes and identified a subset of CD163+ Kupffer cells that migrate towards infected cells during infection. These data offer the first insight into the heterogeneous microenvironment that surrounds the infected hepatocyte and provide insights into how the parasite may alter its milieu to influence its survival and modulate immunity.


Author(s):  
Yingxuan Zhang ◽  
Si Chen ◽  
Xiaofeng Chen ◽  
Huimin Zhang ◽  
Xuge Huang ◽  
...  

The early diagnosis and treatment of ectopic pregnancy (EP) remains a major challenge. Despite a known link between vaginal microbiota and female reproductive health, few studies have focused on the association between vaginal microbiota and pregnancy location. This nested case-control study aimed to characterize the vaginal microbiota in tubal pregnancy (TP) among symptomatic women in early pregnancy. Women with symptomatic early pregnancy of unknown location (PUL) were included in this study. 16S rDNA gene sequencing was performed to assess vaginal microbial diversity and relative abundance. Machine learning and multivariate logistic regression were also used to evaluate the association between Gardnerella and TP. The results indicate that the vaginal microbiome in TP was more diverse (Shannon, p < 0.05) and was different in composition to that of women with intrauterine pregnancy (IUP) (weighted Unifrac, R = 0.08, p = 0.01). The genus Gardnerella was significantly enriched in TP. The XGBoost analysis was able to classify Gardnerella-induced TP more reliably (AUC = 0.621). Moreover, after adjusting potential confounders, our results indicate a robust association between Gardnerella and TP (as a continuous variable, adjusted OR: 12.0, 95% CI: 2.1–67.4, p < 0.01; as a categorical variable (≥0.85%), and adjusted OR: 4.2, 95% CI: 2.0–8.8, p < 0.01). In conclusion, we found that higher virginal Gardnerella levels were associated with TP in women with symptomatic early pregnancy.


Author(s):  
Abigail M. Forson ◽  
Colin W. K. Rosman ◽  
Theo G. van Kooten ◽  
Henny C. van der Mei ◽  
Jelmer Sjollema

Advancements in contemporary medicine have led to an increasing life expectancy which has broadened the application of biomaterial implants. As each implant procedure has an innate risk of infection, the number of biomaterial-associated infections keeps rising. Staphylococcus aureus causes 34% of such infections and is known as a potent biofilm producer. By secreting micrococcal nuclease S. aureus is able to escape neutrophil extracellular traps by cleaving their DNA-backbone. Also, micrococcal nuclease potentially limits biofilm growth and adhesion by cleaving extracellular DNA, an important constituent of biofilms. This study aimed to evaluate the impact of micrococcal nuclease on infection persistence and biofilm formation in a murine biomaterial-associated infection-model with polyvinylidene-fluoride mesh implants inoculated with bioluminescent S. aureus or its isogenic micrococcal nuclease deficient mutant. Supported by results based on in-vivo bioluminescence imaging, ex-vivo colony forming unit counts, and histological analysis it was found that production of micrococcal nuclease enables S. aureus bacteria to evade the immune response around an implant resulting in a persistent infection. As a novel finding, histological analysis provided clear indications that the production of micrococcal nuclease stimulates S. aureus to form biofilms, the presence of which extended neutrophil extracellular trap formation up to 13 days after mesh implantation. Since micrococcal nuclease production appeared vital for the persistence of S. aureus biomaterial-associated infection, targeting its production could be a novel strategy in preventing biomaterial-associated infection.


Author(s):  
Giuseppe Privitera ◽  
Nitish Rana ◽  
Franco Scaldaferri ◽  
Alessandro Armuzzi ◽  
Theresa T. Pizarro

Colorectal cancer (CRC) is one of the most prevalent and deadly forms of cancer in Western countries. Inflammation is a well-known driver of colonic carcinogenesis; however, its role in CRC extends beyond colitis-associated cancer. Over the last decades, numerous associations between intestinal dysbiosis and CRC have been identified, with more recent studies providing mechanistic evidence of a causative relationship. Nonetheless, much remains to be discovered regarding the precise implications of microbiome alterations in the pathogenesis of CRC. Research confirms the importance of a bidirectional crosstalk between the gut microbiome and the mucosal immune system in which inflammasomes, multiprotein complexes that can sense “danger signals,” serve as conduits by detecting microbial signals and activating innate immune responses, including the induction of microbicidal activities that can alter microbiome composition. Current evidence strongly supports an active role for this “inflammasome–microbiome axis” in the initiation and development of CRC. Furthermore, the gasdermin (GSDM) family of proteins, which are downstream effectors of the inflammasome that are primarily known for their role in pyroptosis, have been recently linked to CRC pathogenesis. These findings, however, do not come without controversy, as pyroptosis is reported to exert both anti- and protumorigenic functions. Furthermore, the multi-faceted interactions between GSDMs and the gut microbiome, as well as their importance in CRC, have only been superficially investigated. In this review, we summarize the existing literature supporting the importance of the inflammasome–microbiota axis, as well as the activation and function of GSDMs, to gain a better mechanistic understanding of CRC pathogenesis.


Author(s):  
Ruixue Huang

Insulin resistance is a hallmark of Alzheimer’s disease (AD), type II diabetes (T2D), and Parkinson’s disease (PD). Emerging evidence indicates that these disorders are typically characterized by alterations in the gut microbiota composition, diversity, and their metabolites. Currently, it is understood that environmental hazards including ionizing radiation, toxic heavy metals, pesticides, particle matter, and polycyclic aromatic hydrocarbons are capable of interacting with gut microbiota and have a non-beneficial health effect. Based on the current study, we propose the hypothesis of “gut microenvironment baseline drift”. According to this “baseline drift” theory, gut microbiota is a temporarily combined cluster of species sharing the same environmental stresses for a short period, which would change quickly under the influence of different environmental factors. This indicates that the microbial species in the gut do not have a long-term relationship; any split, division, or recombination may occur in different environments. Nonetheless, the “baseline drift” theory considers the critical role of the response of the whole gut microbiome. Undoubtedly, this hypothesis implies that the gut microbiota response is not merely a “cross junction” switch; in contrast, the human health or disease is a result of a rich palette of gut-microbiota-driven multiple-pathway responses. In summary, environmental factors, including hazardous and normal factors, are critical to the biological impact of the gut microbiota responses and the dual effect of the gut microbiota on the regulation of biological functions. Novel appreciation of the role of gut microbiota and environmental hazards in the insulin resistance would shed new light on insulin resistance and also promote the development of new research direction and new overcoming strategies for patients.


Author(s):  
Shaosong Xi ◽  
Yunguang Wang ◽  
Chenghao Wu ◽  
Weihua Peng ◽  
Ying Zhu ◽  
...  

BackgroundGut–microbiota–brain axis links the relationship between intestinal microbiota and sepsis-associated encephalopathy (SAE). However, the key mediators between them remain unclear.MethodsMemory test was determined by Water maze. Intestinal flora was measured by 16S RNA sequencing. Neurotransmitter was detected by high-performance liquid chromatography (HPLC). Histopathology was determined by H&E, immunofluorescence (IF), and terminal-deoxynucleoitidyl transferase mediated nick end labeling (TUNEL) staining. Flow cytometry was employed to determine the proportion of macrophages.ResultsFecal microbiota transplantation (FMT) relieved hippocampus impairment of SAE rats by inhibiting inflammation cytokine secretion, the expression of IBA-1 and neurotransmitter disturbance, and cell apoptosis and autophagy, accompanied by the reduced M1 polarization and M1 pro-inflammation factors produced by macrophages in mesenteric lymph nodes (MLNs). Actually, M1 polarization in SAE rats depended on intestinal epithelial cell (IEC)-derived exosome. GW4869-initiated inhibition of exosome secretion notably abolished M1 polarization and the secretion of IL-1β. However, GW4869-mediated improvement of hippocampus impairment was counteracted by the delivery of recombinant interleukin (IL)-1β to hippocampus. Mechanistically, IEC-derived exosome induced the excessive circulating IL-1β produced by CP-R048 macrophages, which subsequently induced damage and apoptosis of hippocampal neurons H19-7 in an autophagy-dependent manner. And reactivation of autophagy facilitates intestinal IL-1β-mediated hippocampal neuron injury.ConclusionCollectively, intestinal flora disturbance induced the exosome release of IECs, which subsequently caused M1 polarization in MLNs and the accumulation of circulating IL-1β. Circulating IL-1β promoted the damage and apoptosis of neurons in an autophagy-dependent manner. Possibly, targeting intestinal flora or IEC-derived exosome contributes to the treatment of SAE.


Author(s):  
Taylor L. T. Wherry ◽  
Rohana Dassanayake ◽  
Eduardo Casas ◽  
Shankumar Mooyottu ◽  
John P. Bannantine ◽  
...  

Mycobacterium avium subspecies paratuberculosis (MAP), the causative agent of ruminant enteritis, targets intestinal macrophages. During infection, macrophages contribute to mucosal inflammation and development of granulomas in the small intestine which worsens as disease progression occurs. Vitamin D3 is an immunomodulatory steroid hormone with beneficial roles in host-pathogen interactions. Few studies have investigated immunologic roles of 25-hydroxyvitamin D3 (25(OH)D3) and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) in cattle, particularly cattle infected with MAP. This study examined the effects of exogenous vitamin D3 on immune responses of monocyte derived macrophages (MDMs) isolated from dairy cattle naturally infected with MAP. MDMs were pre-treated with ± 100 ng/ml 25(OH)D3 or ± 4 ng/ml 1,25(OH)2D3, then incubated 24 hrs with live MAP in the presence of their respective pre-treatment concentrations. Following treatment with either vitamin D3 analog, phagocytosis of MAP by MDMs was significantly greater in clinically infected animals, with a greater amount of live and dead bacteria. Clinical cows had significantly less CD40 surface expression on MDMs compared to subclinical cows and noninfected controls. 1,25(OH)2D3 also significantly increased nitrite production in MAP infected cows. 1,25(OH)2D3 treatment played a key role in upregulating secretion of pro-inflammatory cytokines IL-1β and IL-12 while downregulating IL-10, IL-6, and IFN-γ. 1,25(OH)2D3 also negatively regulated transcripts of CYP24A1, CYP27B1, DEFB7, NOS2, and IL10. Results from this study demonstrate that vitamin D3 compounds, but mainly 1,25(OH)2D3, modulate both pro- and anti-inflammatory immune responses in dairy cattle infected with MAP, impacting the bacterial viability within the macrophage.


Author(s):  
Jieqiong Wang ◽  
Huiying Zhao ◽  
Youzhong An

Angiotensin converting enzyme 2 (ACE2), a transmembrane glycoprotein, is an important part of the renin-angiotensin system (RAS). In the COVID-19 epidemic, it was found to be the receptor of severe acute respiratory syndrome coronavirus 2 (SARS-COV-2). ACE2 maintains homeostasis by inhibiting the Ang II-AT1R axis and activating the Ang I (1-7)-MasR axis, protecting against lung, heart and kidney injury. In addition, ACE2 helps transport amino acids across the membrane. ACE2 sheds from the membrane, producing soluble ACE2 (sACE2). Previous studies have pointed out that sACE2 plays a role in the pathology of the disease, but the underlying mechanism is not yet clear. Recent studies have confirmed that sACE2 can also act as the receptor of SARS-COV-2, mediating viral entry into the cell and then spreading to the infective area. Elevated concentrations of sACE2 are more related to disease. Recombinant human ACE2, an exogenous soluble ACE2, can be used to supplement endogenous ACE2. It may represent a potent COVID-19 treatment in the future. However, the specific administration concentration needs to be further investigated.


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