Publications by authors named "Phoenicia Quach"
Article Synopsis
- - Regulatory CD8 T cells (CD8 Treg) usually help control harmful CD4 T cells, but in autoimmune diseases, they often fail, partly due to inhibitory receptors that limit their activation.
- - A new bispecific antibody called MTX-101 targets these inhibitory receptors and CD8 T cells to enhance the ability of CD8 Treg to eliminate pathogenic CD4 T cells in various experimental models.
- - In studies, MTX-101 improved CD8 Treg activity, reduced harmful CD4 T cell expansion, and protected tissues from damage without triggering excessive inflammation, showing promise for treating autoimmune disorders.
Article Synopsis
- Bacteria like Group B Streptococcus (GBS) can lead to serious issues during pregnancy, including preterm births and infections in newborns.
- GBS produces an enzyme called hyaluronidase that breaks down a component called hyaluronan in the host, which weakens the immune response and allows the bacteria to spread more easily.
- This study reveals that GBS's hyaluronidase (HylB) promotes immune suppression during pregnancy and involves specific immune receptors (TLR2, TLR4) and the cytokine IL-10, highlighting the need for better understanding to create effective treatment options.
Article Synopsis
- Hemolytic lipids, like granadaene from Group B Streptococcus (GBS), are harmful to immune cells and contribute to infections in both newborns and adults.
- Immunization with a synthetic safe version of granadaene (R-P4) has shown to enhance immune responses, leading to improved protection against GBS infections in mice.
- Key immune cells, particularly CD4+ T cells and iNKT cells, play a crucial role in this protection, suggesting that targeting lipid cytotoxins could be an effective strategy for developing new therapies.
Article Synopsis
- Invasive bacterial infections, particularly from Group B streptococcus (GBS), are a significant health concern, with gender differences affecting susceptibility, as shown in studies on factor XIIIA-deficient female mice.
- Male mice with higher levels of factor XIIIA displayed increased resistance to GBS, while administering FXIIIA enhanced resistance in male mice, and inhibiting it reduced resistance in females.
- The study also found that FXIIIA helps trap GBS within fibrin clots by linking it to fibronectin, and mast cell-derived FXIIIA plays a crucial role in defending against GBS infections, highlighting the complex interplay of gender and immune response.
Group B streptococci (GBS) cause a range of invasive maternal-fetal diseases during pregnancy and post-partum. However, invasive infections in non-pregnant adults are constantly increasing. These include sepsis and streptococcal toxic shock syndrome, which are often complicated by systemic coagulation and thrombocytopenia.
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- - The GBS-NN vaccine, designed to combat Group B Streptococcus (GBS) infections during pregnancy, has shown safety in nonpregnant women but needs further study for pregnant populations.
- - Mouse model tests revealed that vaccinated mice produced more GBS-specific antibodies, leading to better outcomes during infections compared to those that received a control treatment.
- - The study suggests that while the vaccine doesn't completely prevent GBS during pregnancy, it reduces fetal deaths and enhances neonatal survival rates after infection, indicating potential benefits of maternal vaccination.
Article Synopsis
- - Invasive bacterial infections, like those caused by Group B streptococci (GBS), significantly raise risks for negative pregnancy outcomes such as preterm birth and stillbirth due to their ability to infect the maternal-fetal area.
- - A research study using a nonhuman primate model revealed that GBS expressing the enzyme hyaluronidase (HylB) led to consistent bacterial invasion into the amniotic cavity, fetal infection, and preterm labor.
- - The findings suggest that HylB allows GBS to evade immune responses and cause preterm labor by increasing certain inflammatory markers, highlighting the need for better strategies to prevent these issues during pregnancy.
Article Synopsis
- Group B streptococci (GBS) are harmful bacteria linked to serious pregnancy and neonatal complications, with a key virulence factor being β-hemolysin/cytolysin (granadaene), which is found on their surfaces.
- The study found that GBS releases pigmented membrane vesicles (MVs) that contain active granadaene and are associated with increased cell death in immune cells.
- These hemolytic MVs enhance the bacteria's ability to survive and worsen disease severity in neonatal mice, suggesting they play a significant role in GBS infection and virulence.
Although certain microbial lipids are toxins, the structural features important for cytotoxicity remain unknown. Increased functional understanding is essential for developing therapeutics against toxic microbial lipids. Group B Streptococci (GBS) are bacteria associated with preterm births, stillbirths, and severe infections in neonates and adults.
View Article and Find Full Text PDFGroup B (GBS) is a β-hemolytic, Gram-positive bacterium that commonly colonizes the female lower genital tract and is associated with fetal injury, preterm birth, spontaneous abortion, and neonatal infections. A major factor promoting GBS virulence is the β-hemolysin/cytolysin, which is cytotoxic to several host cells. We recently showed that the ornithine rhamnolipid pigment, Granadaene, produced by the gene products of the operon, is hemolytic.
View Article and Find Full Text PDFThirteen percent of pregnancies result in preterm birth or stillbirth, accounting for fifteen million preterm births and three and a half million deaths annually. A significant cause of these adverse pregnancy outcomes is in utero infection by vaginal microorganisms. To establish an in utero infection, vaginal microbes enter the uterus by ascending infection; however, the mechanisms by which this occurs are unknown.
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- Preterm birth is a significant cause of neonatal death and is often triggered by infections that ascend from the lower genital tract, affecting the placenta and fetus.
- The study investigates the cervical mucus plug (CMP) from healthy pregnancies to identify its antimicrobial properties against group B streptococcus (GBS), a bacteria linked to preterm birth.
- Although the antimicrobial peptides found in CMPs are not concentrated enough to kill GBS directly, they can activate leukocytes, enhancing the body's ability to kill bacteria, which suggests the CMP plays a role in preventing infections that could lead to preterm birth.
Group B streptococci (GBS) are encapsulated, β-hemolytic bacteria that are a common cause of infections in human newborns and certain adults. Two factors important for GBS virulence are the sialic acid capsular polysaccharide that promotes immune evasion and the hemolytic pigment that induces host cell cytotoxcity. These virulence factors are often oppositely regulated by the CovR/CovS two-component system.
View Article and Find Full Text PDFGroup B streptococci (GBS) are Gram-positive bacteria that are a leading cause of neonatal infections. Most invasive isolates are β-hemolytic, and hemolytic activity is critical for GBS virulence. Although nonhemolytic GBS strains are occasionally isolated, they are often thought to be virulence attenuated.
View Article and Find Full Text PDFUnlabelled: Preterm birth increases the risk of adverse birth outcomes and is the leading cause of neonatal mortality. A significant cause of preterm birth is in utero infection with vaginal microorganisms. These vaginal microorganisms are often recovered from the amniotic fluid of preterm birth cases.
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