Journal of Biomedical Science

Streptococcus pneumoniae is a common cause of post-influenza secondary bacterial infection, which results in excessive morbidity and mortality. Although 13-valent pneumococcal conjugate vaccine (PCV13) vaccination programs have decreased the incidence of pneumococcal pneumonia, PCV13 failed to prevent serotype 3 pneumococcal disease as effectively as other vaccine serotypes. We aimed to investigate the mechanisms underlying the co-pathogenesis of influenza virus and serotype 3 pneumococci. We carried out a genome-wide screening of a serotype 3 S. pneumoniae transposon insertion mutant library in a mouse model of coinfection with influenza A virus (IAV) to identify the bacterial factors required for this synergism. Direct, high-throughput sequencing of transposon insertion sites identified 24 genes required for both coinfection and bacterial infection alone. Targeted deletion of the putative aminotransferase (PA) gene decreased bacterial growth, which was restored by supplementation with methionine. The bacterial burden in a coinfection with the PA gene deletion mutant and IAV in the lung was lower than that in a coinfection with wild-type pneumococcus and IAV, but was significantly higher than that in an infection with the PA gene deletion mutant alone. These data suggest that IAV infection alters host metabolism to benefit pneumococcal fitness and confer higher susceptibility to pneumococcal infection. We further demonstrated that bacterial growth was increased by supplementation with methionine or IAV-infected mouse lung homogenates. The data indicates that modulation of host metabolism during IAV infection may serve as a potential therapeutic intervention against secondary bacterial infections caused by serotype 3 pneumococci during IAV outbreaks in the future.

Stem cell activity is subject to non-cell-autonomous regulation from the local microenvironment, or niche. In adaption to varying physiological conditions and the ever-changing external environment, the stem cell niche has evolved with multifunctionality that enables stem cells to detect these changes and to communicate with remote cells/tissues to tailor their activity for organismal needs. The cyclic growth of hair follicles is powered by hair follicle stem cells (HFSCs). Using HFSCs as a model, we categorize niche cells into 3 functional modules, including signaling, sensing and message-relaying. Signaling modules, such as dermal papilla cells, immune cells and adipocytes, regulate HFSC activity through short-range cell-cell contact or paracrine effects. Macrophages capacitate the HFSC niche to sense tissue injury and mechanical cues and adipocytes seem to modulate HFSC activity in response to systemic nutritional states. Sympathetic nerves implement the message-relaying function by transmitting external light signals through an ipRGC-SCN-sympathetic circuit to facilitate hair regeneration. Hair growth can be disrupted by niche pathology, e.g. dysfunction of dermal papilla cells in androgenetic alopecia and influx of auto-reacting T cells in alopecia areata and lichen planopilaris. Understanding the functions and pathological changes of the HFSC niche can provide new insight for the treatment of hair loss.

Bacterial adherence to epithelial cells is a key virulence trait of pathogenic bacteria. The type 1 fimbriae and the P-fimbriae of uropathogenic Escherichia coli (UPEC) have both been described to be important for the establishment of urinary tract infections (UTI). To explore the interactions between the host and bacterium responsible for the different environments of UPEC invasion, we examined the effect of pH and osmolarity on UPEC strain J96 fimbrial expression, and subsequent J96-induced interleukin-8 (IL-8) expression in different uroepithelial cells. The J96 strain grown in high pH with low osmolarity condition was favorable for the expression of type 1 fimbriae; whereas J96 grown in low pH with high osmolarity condition was beneficial for P fimbriae expression. Type 1 fimbriated J96 specifically invaded bladder 5637 epithelial cells and induced IL-8 expression. On the contrary, P fimbriated J96 invaded renal 786-O epithelial cells and induced IL-8 expression effectively. Type 1 fimbriated J96-induced IL-8 induction involved the p38, as well as ERK, JNK pathways, which leads to AP-1-mediated gene expression. P fimbriated J96-induced augmentation of IL-8 expression mainly involved p38-mediated AP-1 and NF-κB transcriptional activation. These results indicate that different expression of fimbriae in J96 trigger differential IL-8 gene regulation pathways in different uroepithelial cells.

Ischemic postconditioning (IPO) has been demonstrated to attenuate ischemia/reperfusion (I/R) injury in the heart and brain, its roles to liver remain to be defined. The study was undertaken to determine if IPO would attenuate liver warm I/R injury and its protective mechanism. Mice were divided into sham, I/R, IPO+I/R (occlusing the porta hepatis for 60 min, then treated for three cycles of 10 sec brief reperfusion consecutively, followed by a persistent reperfusion); L-NAME+ sham (L-NAME, 16 mg/kg, i.v., 5 min before repefusion); L-NAME+I/R; and L-NAME+ IPO. Blood flow of caudate and left lobe of the liver was blocked. Functional and morphologic changes of livers were evaluated. Contents of nitric oxide, eNOS and iNOS in serum were assayed. Concentration of eNOS, iNOS, malondialdehyde (MDA) and activity of superoxide dismutase (SOD) in hepatic tissue were also measured. Expressions of Akt, p-Akt and HIF-1α protein were determined by western blot. Expressions of TNF-α and ICAM-1 were measured by immunohistochemistry and RT-PCR. IPO attenuated the dramatically functional and morphological injuries. The levels of ALT was significantly reduced in IPO+I/R group (p < 0.05). Contents of nitric oxide and eNOS in serum were increased in the IPO+I/R group (p < 0.05). IPO also up-regulated the concentration of eNOS, activity of SOD in hepatic tissue (p < 0.05), while reduced the concentration of MDA (p < 0.05). Moreover, protein expressions of HIF-1α and p-Akt were markedly enhanced in IPO+I/R group. Protein and mRNA expression of TNF-α and ICAM-1 were markedly suppressed by IPO (p < 0.05). These protective effects of IPO could be abolished by L-NAME. We found that IPO increased the content of NO and attenuated the overproduction of ROS and I/R-induced inflammation. Increased NO contents may contribute to increasing HIF-1α level, and HIF-1α and NO would simultaneously protect liver from I/R injury. These findings suggested IPO may have the therapeutic potential through Akt-eNOS-NO-HIF pathway for the better management of liver I/R injury.

Reduced cell spreading is a prominent feature of aged dermal fibroblasts in human skin in vivo. Mitochondrial DNA (mtDNA) common deletion has been reported to play a role in the human aging process, however the relationship between age-related reduced cell spreading and mtDNA common deletion has not yet been reported. To examine mtDNA common deletion in the dermis of aged human skin, the epidermis was removed from full-thickness human skin samples using cryostat. mtDNA common deletion was significantly elevated in the dermis of both naturally aged and photoaged human skin in vivo. To examine the relationship between age-related reduced cell spreading and mtDNA common deletion, we modulated the shape of dermal fibroblasts by disrupting the actin cytoskeleton. Reduced cell spreading was associated with a higher level of mtDNA common deletion and was also accompanied by elevated levels of endogenous reactive oxygen species (ROS). Boosting cellular antioxidant capacity by using antioxidants was found to be protective against mtDNA common deletion associated with reduced cell spreading. mtDNA common deletion is highly prevalent in the dermis of both naturally aged and photoaged human skin in vivo. mtDNA common deletion in response to reduced cell spreading is mediated, at least in part, by elevated oxidative stress in human dermal fibroblasts. These data extend current understanding of the mitochondrial theory of aging by identifying the connection between mtDNA common deletion and age-related reduction of cell spreading.

Head and neck squamous carcinoma (HNSCC) is one of the most invasive types of cancer with high mortality. A previous study has indicated that low levels of let-7d and miR-205 in HNSCC patients are correlated with poor survival. Let-7d and miR-205 are tumor suppressors and regulators of epithelial-to-mesenchymal transition (EMT). However, it is unclear if let-7d and miR-205 together influence cancer cells. To determine if let-7d and miR-205 expression levels influence HNSCC patient outcome. The TCGA expression data for let-7d, miR-205 and their targets as well as clinical data were downloaded from cBioPortal and starBase v2.0 for 307 patients. The expression levels of let-7d and miR-205 were verified according to clinicopathological parameters. The let-7d and miR-205 high- and low-expression groups as well as disease-free survival (DFS), overall survival (OS) and expression levels of genes related to EMT, cancer stem cells, metastasis, cell cycle, drug response and irradiation response were investigated. Let-7d and miR-205 were frequently upregulated in HNSCC compared to normal samples, and ROC analysis showed high discrimination ability for let-7d and miR-205 (area 0.7369 and 0.7739, respectively; p < 0.0001). Differences between expression levels of let-7d or miR-205 and grade, angiolymphatic invasion, perineural invasion and alcohol consumption were indicated. No differences were observed in N-stage, tumor localization, gender or patient age. Patients with lower let-7d levels and higher miR-205 levels had significantly better OS (p = 0.0325) than patients with higher let-7d levels and lower miR-205 levels. In the low let-7d level and high miR-205 level group, a lower percentage of more advanced cancers was observed. The analysis of genes related to EMT, cancer stem cells, metastasis, cell cycle, drug response and irradiation response revealed a distinct phenotype of analyzed groups. The present findings indicated that let-7d down-regulation and miR-205 overexpression create a unique cell phenotype with different behavior compared to cells with upregulated let-7d and down-regulated miR-205. Thus, let-7d and miR-205 are good candidates for new HNSCC biomarkers.

Chronic inflammation may lead to endothelial dysfunction, which manifests as an impaired coronary reactivity. Impairment in coronary flow reserve (CFR), preceding the clinical symptoms of coronary artery disease, can be measured noninvasively by positron emission tomography. Myeloperoxidase (MPO) is an oxidative enzyme present in phagocytes and atherosclerotic lesions. The MPO gene has a promoter polymorphism (−463G/A) which affects gene transcription. Whether these variants associate with coronary artery function is not known. Myocardial blood flow at rest and during adenosine-induced hyperemia was assessed in 49 healthy young men with normal or slightly elevated serum total cholesterol. These subjects were divided into high (G/G) and low (A/G, A/A) MPO expression groups and effect of MPO genotype on myocardial blood flow was evaluated. We found a significant difference between MPO genotypes in CFR after adjusting for age, body mass index, smoking and family history of cardiovascular disease (p=0.019). Men with G/G genotype had 18.1% lower CFR than subjects with low-expression genotypes (A/G and A/A). This was due to an 11.5% lower adenosine-stimulated flow of the G/G genotype carriers (p=0.049). These findings provide evidence that MPO polymorphism is associated with coronary artery reactivity. However, the number of individuals investigated was low and our observation should be confirmed by a larger number of subjects.

Jaundice is a common symptom of inherited or acquired liver diseases or a manifestation of diseases involving red blood cell metabolism. Recent progress has elucidated the molecular mechanisms of bile metabolism, hepatocellular transport, bile ductular development, intestinal bile salt reabsorption, and the regulation of bile acids homeostasis. The major genetic diseases causing jaundice involve disturbances of bile flow. The insufficiency of bile salts in the intestines leads to fat malabsorption and fat-soluble vitamin deficiencies. Accumulation of excessive bile acids and aberrant metabolites results in hepatocellular injury and biliary cirrhosis. Progressive familial intrahepatic cholestasis (PFIC) is the prototype of genetic liver diseases manifesting jaundice in early childhood, progressive liver fibrosis/cirrhosis, and failure to thrive. The first three types of PFICs identified (PFIC1, PFIC2, and PFIC3) represent defects in FIC1 (ATP8B1), BSEP (ABCB11), or MDR3 (ABCB4). In the last 5 years, new genetic disorders, such as TJP2, FXR, and MYO5B defects, have been demonstrated to cause a similar PFIC phenotype. Inborn errors of bile acid metabolism also cause progressive cholestatic liver injuries. Prompt differential diagnosis is important because oral primary bile acid replacement may effectively reverse liver failure and restore liver functions. DCDC2 is a newly identified genetic disorder causing neonatal sclerosing cholangitis. Other cholestatic genetic disorders may have extra-hepatic manifestations, such as developmental disorders causing ductal plate malformation (Alagille syndrome, polycystic liver/kidney diseases), mitochondrial hepatopathy, and endocrine or chromosomal disorders. The diagnosis of genetic liver diseases has evolved from direct sequencing of a single gene to panel-based next generation sequencing. Whole exome sequencing and whole genome sequencing have been actively investigated in research and clinical studies. Current treatment modalities include medical treatment (ursodeoxycholic acid, cholic acid or chenodeoxycholic acid), surgery (partial biliary diversion and liver transplantation), symptomatic treatment for pruritus, and nutritional therapy. New drug development based on gene-specific treatments, such as apical sodium-dependent bile acid transporter (ASBT) inhibitor, for BSEP defects are underway. Understanding the complex pathways of jaundice and cholestasis not only enhance insights into liver pathophysiology but also elucidate many causes of genetic liver diseases and promote the development of novel treatments.