Production of inactivated gram-positive and gram-negative species with preserved cellular morphology and integrity

Photocatalytic Bacterial Destruction and Mineralization by TiO2-Based Photocatalysts: A Mini Review

This work presents an overview of the reports on the bacterial cell photocatalytic destruction and mineralization process in the presence of TiO2-based photocatalysts. The presented research included experiments conducted in air and water. Numerous works confirmed that a photocatalytic process with TiO2 led to bacteria and their organic residues' mineralization. Additionally, based on the obtained results, a possible two-stage mechanism of photocatalytic mineralization in the presence of TiO2-based materials was proposed. To help future studies, challenges of photocatalytic microorganism mineralization are also proposed. There are some aspects that need to be addressed, such as the lack of standardization of conducted research or relatively small amount of research on photocatalytic microorganism mineralization. According to our best knowledge, in the available literature, no work regarding a summary of previous research on photocatalytic bacterial mineralization process was found.

Commensal skin bacteria exacerbate inflammation and delay skin barrier repair

The skin microbiome can both trigger beneficial immune stimulation and pose a potential infection threat. Previous studies have shown that colonization of mouse skin with the model human skin commensal Staphylococcus epidermidis is protective against subsequent excisional wound or pathogen challenge. However, less is known about concurrent skin damage and exposure to commensal microbes, despite growing interest in interventional probiotic therapy. Here, we address this open question by applying commensal skin bacteria at a high dose to abraded skin. While depletion of the skin microbiome via antibiotics delayed repair from damage, probiotic-like application of commensals-- including the mouse commensal Staphylococcus xylosus, three distinct isolates of S. epidermidis, and all other tested human skin commensals-- also significantly delayed barrier repair. Increased inflammation was observed within four hours of S. epidermidis exposure and persisted through day four, at which point the skin displayed a chronic wound-like inflammatory state with increased neutrophil infiltration, increased fibroblast activity, and decreased monocyte differentiation. Transcriptomic analysis suggested that the prolonged upregulation of early canonical proliferative pathways inhibited the progression of barrier repair. These results highlight the nuanced role of members of the skin microbiome in modulating barrier integrity and indicate the need for caution in their development as probiotics.

A New Theranostic Platform Against Gram-Positive Bacteria Based on Near-Infrared-Emissive Aggregation-Induced Emission Nanoparticles

Infections induced by Gram-positive bacteria pose a great threat to public health. Antibiotic therapy, as the first chosen strategy against Gram-positive bacteria, is inevitably associated with antibiotic resistance selection. Novel therapeutic strategies for the discrimination and inactivation of Gram-positive bacteria are thus needed. Here, a specific type of aggregation-induced emission luminogen (AIEgen) with near-infrared fluorescence emission as a novel antibiotic-free therapeutic strategy against Gram-positive bacteria is proposed. With the combination of a positively charged group into a highly twisted architecture, self-assembled AIEgens (AIE nanoparticles (NPs)) at a relatively low concentration (5 µm) exhibited specific binding and photothermal effect against living Gram-positive bacteria both in vitro and in vivo. Moreover, toxicity assays demonstrated excellent biocompatibility of AIE NPs at this concentration. All these properties make the AIE NPs as a novel generation of theranostic platform for combating Gram-positive bacteria and highlight their promising potential for in vivo tracing of such bacteria.

Bovine neutrophils stimulated with Streptococcus uberis induce neutrophil extracellular traps, and cause cytotoxicity and transcriptional upregulation of inflammatory cytokine genes in bovine mammary epithelial cells

This study aimed to understand the response of neutrophils stimulated by Streptococcus uberis, a major cause of mastitis. It was found that the production of neutrophil extracellular traps (NETs) was induced in milk clots from mastitic milk produced by S. uberis-infected bovine udders. The release of NETs from neutrophils stimulated by S. uberis was investigated. Bovine neutrophils cocultured with S. uberis in vitro released the components of NETs, which contained extracellular DNA and elastase. Bovine mammary epithelial cells (BMECs) incubated in coculture supernatants containing components of NETs, caused cytotoxicity and transcriptional upregulation of inflammatory cytokines, including of interleukin (IL) -1β, tumor necrosis factor (TNF)-α, IL-6, and IL-8, in BMECs. These findings suggest that bovine neutrophils stimulated by S. uberis induce responses that cause exacerbated inflammation, such as NET formation, cytotoxicity against BMECs, and increased production of inflammatory cytokines. Bovine neutrophil responses stimulated by S. uberis could be involved in the progression of S. uberis-induced mastitis.

Commensal skin bacteria exacerbate inflammation and delay skin healing

The skin microbiome can both trigger beneficial immune stimulation and pose a potential infection threat. Previous studies have shown that colonization of mouse skin with the model human skin commensal Staphylococcus epidermidis is protective against subsequent excisional wound or pathogen challenge. However, less is known about concurrent skin damage and exposure to commensal microbes, despite growing interest in interventional probiotic therapy. Here, we address this open question by applying commensal skin bacteria at a high dose to abraded skin. While depletion of the skin microbiome via antibiotics delayed repair from damage, application of commensals-- including the mouse commensal Staphylococcus xylosus, three distinct isolates of S. epidermidis, and all other tested human skin commensals-- also significantly delayed barrier repair. Increased inflammation was observed within four hours of S. epidermidis exposure and persisted through day four, at which point the skin displayed a chronic-wound-like inflammatory state with increased neutrophil infiltration, increased fibroblast activity, and decreased monocyte differentiation. Transcriptomic analysis suggested that the prolonged upregulation of early canonical proliferative pathways inhibited the progression of barrier repair. These results highlight the nuanced role of members of the skin microbiome in modulating barrier integrity and indicate the need for caution in their development as probiotics.

Evaluation of the Combined Administration of Chlorella fusca and Vibrio proteolyticus in Diets for Chelon labrosus: Effects on Growth, Metabolism, and Digestive Functionality

This study aimed to evaluate the combined effect of dietary Chlorella fusca and ethanol-inactivated Vibrio proteolyticus DCF12.2 (C + V diet) in Chelon labrosus juveniles, highlighting their nutritional, physiological, and morphological effects. The results showed that the combined dietary inclusion of C. fusca and V. proteolyticus significantly enhanced growth performance and feed utilization compared to the control group. The C + V diet increased the fish lipid quality index (FLQ), n-3 polyunsaturated fatty acids, and n-3/n-6 ratio, which might be beneficial in terms of human nutrition. The C + V diet considerably increased carbohydrate metabolic activity by statistically boosting plasma glucose. The dietary inclusion of C. fusca in conjunction with V. proteolyticus increased metabolic enzyme activity as well as intestinal absorption capacity compared to that found in the control group. In conclusion, the experimental diet was suitable for feeding C. labrosus, increasing their growth and the nutritional characteristics of the muscle and intestine, without causing tissue damage.

Dermatopathology Laboratory Green Initiatives

OBJECTIVES

Climate change and the accumulation of greenhouse gases pose challenges for humanity. The laboratory can reduce the environmental impact of routine operations.

METHODS

Our laboratory implemented several recycling initiatives in 2021, including shredding plastic and recycling 10% formalin, xylene, and reagent alcohols. Additional insulation has reduced electricity costs, and we have plans to derive 100% of our electricity from solar in 2022.

RESULTS

Recycling leads to decreases in reagent purchase by several hundred gallons. Our lab reduced its carbon footprint by a minimum of 68.52 tons, with an anticipated $43,000 savings in purchases and waste disposal during 2022.

CONCLUSIONS

Regardless of an individual's environmental consciousness, green initiatives have several tangible benefits. Recycling helps mitigate climate change and decrease the laboratory's carbon footprint. These measures also insulate the laboratory from supply shortages and lead to significant, tangible monetary savings.

Biochemical Analysis of Leukocytes after In Vitro and In Vivo Activation with Bacterial and Fungal Pathogens Using Raman Spectroscopy

Biochemical information from activated leukocytes provide valuable diagnostic information. In this study, Raman spectroscopy was applied as a label-free analytical technique to characterize the activation pattern of leukocyte subpopulations in an in vitro infection model. Neutrophils, monocytes, and lymphocytes were isolated from healthy volunteers and stimulated with heat-inactivated clinical isolates of Candida albicans, Staphylococcus aureus, and Klebsiella pneumoniae. Binary classification models could identify the presence of infection for monocytes and lymphocytes, classify the type of infection as bacterial or fungal for neutrophils, monocytes, and lymphocytes and distinguish the cause of infection as Gram-negative or Gram-positive bacteria in the monocyte subpopulation. Changes in single-cell Raman spectra, upon leukocyte stimulation, can be explained with biochemical changes due to the leukocyte’s specific reaction to each type of pathogen. Raman spectra of leukocytes from the in vitro infection model were compared with spectra from leukocytes of patients with infection (DRKS-ID: DRKS00006265) with the same pathogen groups, and a good agreement was revealed. Our study elucidates the potential of Raman spectroscopy-based single-cell analysis for the differentiation of circulating leukocyte subtypes and identification of the infection by probing the molecular phenotype of those cells.

Viability Status-Dependent Effect of Bifidobacterium longum ssp. longum CCM 7952 on Prevention of Allergic Inflammation in Mouse Model

The classical definition of probiotics states that bacteria must be alive to be beneficial for human organism. However, recent reports show that inactivated bacteria or their effector molecules can also possess such properties. In this study, we investigated the physical and immunomodulatory properties of four Bifidobacterium strains in the heat-treated (HT) and untreated (UN) forms. We showed that temperature treatment of bacteria changes their size and charge, which affects their interaction with epithelial and immune cells. Based on the in vitro assays, we observed that all tested strains reduced the level of OVA-induced IL-4, IL-5, and IL-13 in the spleen culture of OVA-sensitized mice. We selected Bifidobacterium longum ssp. longum CCM 7952 (Bl 7952) for further analysis. In vivo experiments confirmed that untreated Bl 7952 exhibited allergy-reducing properties when administered intranasally to OVA-sensitized mice, which manifested in significant suppression of airway inflammation. Untreated Bl 7952 decreased local and systemic levels of Th2 related cytokines, OVA-specific IgE antibodies and simultaneously inhibited airway eosinophilia. In contrast, heat-treated Bl 7952 was only able to reduce IL-4 levels in the lungs and eosinophils in bronchoalveolar lavage, but increased neutrophil and macrophage numbers. We demonstrated that the viability status of Bl 7952 is a prerequisite for the beneficial effects of bacteria, and that heat treatment reduces but does not completely abolish these properties. Further research on bacterial effector molecules to elucidate the beneficial effects of probiotics in the prevention of allergic diseases is warranted.

Growth rate alterations of human colorectal cancer cells by 157 gut bacteria

Several bacteria in the human gut microbiome have been associated with colorectal cancer (CRC) by high-throughput screens. In some cases, molecular mechanisms have been elucidated that drive tumorigenesis, including bacterial membrane proteins or secreted molecules that interact with the human cancer cells. For most gut bacteria, however, it remains unknown if they enhance or inhibit cancer cell growth. Here, we screened bacteria-free supernatants (secretomes) and inactivated cells of over 150 cultured bacterial strains for their effects on cell growth. We observed family-level and strain-level effects that often differed between bacterial cells and secretomes, suggesting that different molecular mechanisms are at play. Secretomes of Bacteroidaceae, Enterobacteriaceae, and Erysipelotrichaceae bacteria enhanced cell growth, while most Fusobacteriaceae cells and secretomes inhibited growth, contrasting prior findings. In some bacteria, the presence of specific functional genes was associated with cell growth rates, including the virulence genes TcdA, TcdB in Clostridiales and FadA in Fusobacteriaceae, which both inhibited growth. Bacteroidaceae cells that enhanced growth were enriched for genes of the cobalamin synthesis pathway, while Fusobacteriaceae cells that inhibit growth were enriched for genes of the ethanolamine utilization pathway. Together, our results reveal how different gut bacteria have wide-ranging effects on cell growth, contribute a better understanding of the effects of the gut microbiome on host cells, and provide a valuable resource for identifying candidate target genes for potential microbiome-based diagnostics and treatment strategies.