Differential effects of low and high doses of lipoteichoic acid on lipopolysaccharide-induced interleukin-6 production

Alleviation of LPS-Induced Inflammation and Septic Shock by Lactiplantibacillus plantarum K8 Lysates

We previously showed that Lactiplantibacillus plantarum K8 and its cell wall components have immunoregulatory effects. In this study, we demonstrate that pre-treatment of L. plantarum K8 lysates reduced LPS-induced TNF-α production in THP-1 cells by down-regulating the early signals of mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB). The down-regulation of signals may be caused by the induction of negative regulators involved in toll-like receptor (TLR)-mediated signaling. However, co-treatment with high concentrations of L. plantarum K8 lysates and lipopolysaccharide (LPS) activated the late signaling of extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and NF-κB pathways and resulted in the induction of absent in melanoma 2 (AIM2) inflammasome-mediated interleukin (IL)-1β secretion. Intraperitoneal injection of L. plantarum K8 lysates in LPS-induced endotoxin shock mice alleviated mortality and reduced serum tumor-necrosis factor (TNF)-α, IL-1β, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels. In addition, the mRNA levels of TNF-α, IL-1β, and IL-6 decreased in livers from mice injected with L. plantarum K8 followed by LPS. Hematoxylin and eosin (H&E) staining of the liver showed that the cell size was enlarged by LPS injection and slightly reduced by L. plantarum K8 lysate pre-injection followed by LPS injection. Macrophage infiltration of the liver also decreased in response to the combination injection compared with mice injected with only LPS. Taken together, our results show that although L. plantarum K8 lysates differentially regulated the production of LPS-induced inflammatory cytokines in THP-1 cells, the lysates inhibited overall inflammation in mice. Thus, this study suggests that L. plantarum K8 lysates could be developed as a substance that modulates immune homeostasis by regulating inflammation.

Pseudomonas poae-Associated Fatal Septic Transfusion Reaction, Peoria, Illinois, USA, 2017

In the United States, fatal transfusion-transmitted infections from red blood cell units are rare. Although this pattern mostly reflects how inhospitable refrigerated red blood cell units are to contaminant growth, fatalities caused by microorganisms that can grow at storage temperature (4°C), but not in standard clinical blood cultures at 37°C, are probably underestimated. We analyzed a fatal red blood cell transfusion in Peoria, Illinois, USA, that occurred in 2017. Samples from the patient's whole blood and the red blood cell unit remained culture-negative during the investigation, despite direct visualization of gram-negative bacilli within the unit immediately after transfusion. We identified the bacteria as Pseudomonas poae, a nonpathogenic pseudomonad carrying multiple cold-shock domain protein genes, and confirmed its cold tolerance and inability to grow at 37°C. Our work indicates transfusion reaction workups need to include testing for psychrophilic organisms, which could explain the cause of other apparently culture-negative transfusion reactions.

A Comparison of Pyrogen Detection Tests in the Quality Control of Meningococcal Conjugate Vaccines: The Applicability of the Monocyte Activation Test

The meningococcal C conjugate vaccine (MenCC) is an interesting model with which to test the efficacy of the Monocyte Activation Test (MAT) as an alternative method of pyrogen testing in the quality control of vaccines. The MenCC that has been produced by Bio-Manguinhos in Brazil is in the final development stage, and, as recommended in the guidelines for MenCC production, its pyrogen content must be determined by using the Limulus Amoebocyte Lysate (LAL) assay and the Rabbit Pyrogen Test (RPT). This represents an ideal opportunity to compare LAL and RPT data with data obtained by using a MAT system with cryopreserved whole blood and IL-6/IL-1β as marker readouts. In order to assess the compatibility of the MAT with MenCC, endotoxin and non-endotoxin pyrogen content was quantified by using MenCC samples spiked with lipopolysaccharide (LPS), lipoteichoic acid or zymosan standards. The presence of the aluminium-based adjuvant interfered with the MAT, increasing the readout of IL-1β in LPS-spiked MenCC batches. This infringed the product-specific validation criteria of the test, and led to IL-6 being chosen as the more suitable marker readout. No pyrogenic contaminants were identified in the MenCC batches tested, demonstrating consistency among the different systems (MAT, RPT and the LAL assay). In conclusion, the introduction of the MAT during MenCC development could contribute to the elimination of animal tests post-licensing, ensuring human protection based on an effective non-animal based method of quality control.

Applicability of the Monocyte Activation Test (MAT) in the quality control of the 17DD yellow fever vaccine

The need for alternatives to animal use in pyrogen testing has been driven by the Three Rs concept. This has resulted in the inclusion of the monocyte activation test (MAT) in the European Pharmacopoeia, 2010. However, some technical and regulatory obstacles must be overcome to ensure the effective implementation of the MAT by the industry, especially for the testing of biological products. The yellow fever (YF) vaccine (17DD-YFV) was chosen for evaluation in this study, in view of: a) the 2016-2018 outbreak of YF in Brazil; b) the increase in demand for 17DD-YFV doses; c) the complex production process with live attenuated virus; d) the presence of possible test interference factors, such as residual process components (e.g. ovalbumin); and e) the need for the investigation of other pyrogens that are not detectable by the methods prescribed in the YF vaccine monograph. The product-specific testing was carried out by using cryopreserved and fresh whole blood, and IL-6 and IL-1β levels were used as the marker readouts. After assessing the applicability of the MAT on a 1:10 dilution of 17DD-YFV, endotoxin and non-endotoxin pyrogens were quantified in spiked batches, by using the lipopolysaccharide and lipoteichoic acid standards, respectively. The quantitative analysis demonstrated the correlation between the MAT and the Limulus amoebocyte lysate (LAL) assays, with respect to the limits of endotoxin recovery in spiked batches and the detection of no pyrogenic contamination in commercial batches of 17DD-YFV. The data demonstrated the applicability of the MAT for 17DD-YFV pyrogen testing, and as an alternative method that can contribute to biological quality control studies.

Soluble factors from biofilm of Candida albicans and Staphylococcus aureus promote cell death and inflammatory response

Background

The objective of this study was to better understand the effects of soluble factors from biofilm of single- and mixed-species Candida albicans (C. albicans) and methicillin-sensitive Staphylococcus aureus (MSSA) cultures after 36 h in culture on keratinocytes (NOK-si and HaCaT) and macrophages (J774A.1). Soluble factors from biofilms of C. albicans and MSSA were collected and incubated with keratinocytes and macrophages, which were subsequently evaluated by cell viability assays (MTT). Lactate dehydrogenase (LDH) enzyme release was measured to assess cell membrane damage to keratinocytes. Cells were analysed by brightfield microscopy after 2 and 24 h of exposure to the soluble factors from biofilm. Cell death was detected by labelling apoptotic cells with annexin V and necrotic cells with propidium iodide (PI) and was visualized via fluorescence microscopy. Soluble factors from biofilm were incubated with J774A.1 cells for 24 h; the subsequent production of NO and the cytokines IL-6 and TNF-α was measured by ELISA.

Results

The cell viability assays showed that the soluble factors of single-species C. albicans cultures were as toxic as the soluble factors from biofilm of mixed cultures, whereas the soluble factors of MSSA cultures were less toxic than those of C. albicans or mixed cultures. The soluble factors from biofilm of mixed cultures were the most toxic to the NOK-si and HaCaT cells, as confirmed by analyses of PI labelling and cell morphology. Soluble factors from biofilm of single-species MSSA and mixed-species cultures induced the production of IL-6, NO and TNF-α by J744A.1 macrophages. The production of IL-6 and NO induced by the soluble factors from biofilm of mixed cultures was lower than that induced by the soluble factors from biofilm of single-species MSSA cultures, whereas the soluble factors from biofilm of C. albicans cultures induced only low levels of NO.

Conclusions

Soluble factors from 36-h-old biofilm of C. albicans and MSSA cultures promoted cell death and inflammatory responses.

Lipoteichoic acid isolated from Lactobacillus plantarum down-regulates UV-induced MMP-1 expression and up-regulates type I procollagen through the inhibition of reactive oxygen species generation

BACKGROUND

Ultraviolet (UV) irradiation from the sun is the primary environmental factor that causes human skin aging. UV irradiation induces the expressions of matrix metalloproteinases (MMPs) and extracellular matrix degrading enzymes. Among the members of MMP family, MMP-1 is an interstitial collagenase that degrades the collagen triple helix. We investigated the effect of Lactobacillus plantarum, well known as useful microorganism, on UV-induced-MMP-1 expression in human dermal fibroblasts.

METHODS

Human dermal fibroblasts (HDF) was pre-stimulated with lipoteichoic acid isolated from L. plantarum followed by UV irradiation. Secreted protein level of MMP-1 was evaluated by Western blot analysis. The phosphorylation of mitogen-activated protein kinases (MAPKs) and nuclear factor-kappa B (NF-κB) from the cell lysates was also examined by western blotting. Electrophoretic mobility-shift assay (EMSA) was used to detect the activated transcription factor, AP-1 and NF-κB. The detection of type 1 procollagen was carried with Procollagen type 1 C-peptide (PIP) EIA kit. The generation of reactive oxygen species (ROS) by LTA and UV irradiation was examined by Griess reagent assay and fluorescence microscope.

RESULTS

We found that lipoteichoic acid (LTA), a cell-wall component of Gram-positive bacteria, isolated from L. plantarum, inhibited MMP-1 expression. Pretreatment with LTA from L. plantarum (pLTA) reduced MMP-1 expression in a dose-dependent manner and inhibited activation of extracellular signal-regulated kinases (ERK) and c-Jun N-terminal kinases (JNK). It also led to the inhibition of DNA binding activity of activator protein-1 (AP-1) and of nuclear factor kappa-light-chain-enhancer of activated B cell (NF-κB). Furthermore, LTA promoted type 1 procollagen synthesis and reduced the generation of ROS induced by UV irradiation.

CONCLUSION

Our study demonstrates that pLTA inhibits degradation of collagen and promotes its synthesis and that pLTA contributes to a decrease in ROS production. Therefore, pLTA from L. plantarum has potential abilities to prevent and treat skin photo-aging.

Reevaluating the hype: four bacterial metabolites under scrutiny

With microbiome research being a fiercely contested playground in science, new data are being published at tremendous pace. The review at hand serves to critically revise four microbial metabolites widely applied in research: butyric acid, flagellin, lipoteichoic acid, and propionic acid. All four metabolites are physiologically present in healthy humans. Nevertheless, all four are likewise involved in pathologies ranging from cancer to mental retardation. Their inflammatory potential is equally friend and foe. The authors systematically analyze positive and negative attributes of the aforementioned substances, indicating chances and dangers with the use of pre- and probiotic therapeutics. Furthermore, the widespread actions of microbial metabolites on distinct organs and diseases are reconciled. Moreover, the review serves as critical discourse on scientific methods commonly employed in microbiome research and comparability as well as reproducibility issues arising thereof.

Lipoteichoic acid (LTA) and lipopolysaccharides (LPS) from periodontal pathogenic bacteria facilitate oncogenic herpesvirus infection within primary oral cells

Kaposi's sarcoma (KS) remains the most common tumor arising in patients with HIV/AIDS, and involvement of the oral cavity represents one of the most common clinical manifestations of this tumor. HIV infection incurs an increased risk for periodontal diseases and oral carriage of a variety of bacteria. Whether interactions involving pathogenic bacteria and oncogenic viruses in the local environment facilitate replication or maintenance of these viruses in the oral cavity remains unknown. In the current study, our data indicate that pretreatment of primary human oral fibroblasts with two prototypical pathogen-associated molecular patterns (PAMPs) produced by oral pathogenic bacteria-lipoteichoic acid (LTA) and lipopolysaccharide (LPS), increase KSHV entry and subsequent viral latent gene expression during de novo infection. Further experiments demonstrate that the underlying mechanisms induced by LTA and/or LPS include upregulation of cellular receptor, increasing production of reactive oxygen species (ROS), and activating intracellular signaling pathways such as MAPK and NF-κB, and all of which are closely associated with KSHV entry or gene expression within oral cells. Based on these findings, we hope to provide the framework of developing novel targeted approaches for treatment and prevention of oral KSHV infection and KS development in high-risk HIV-positive patients.