Nature of epigenetic aging from a single-cell perspective.

Age-related changes in DNA methylation (DNAm) form the basis of the most robust predictors of age-epigenetic clocks-but a clear mechanistic understanding of exactly which aspects of aging are quantified by these clocks is lacking. Here, to clarify the nature of epigenetic aging, we juxtapose the dynamics of tissue and single-cell DNAm in mice. We compare these changes during early development with those observed during adult aging in mice, and corroborate our analyses with a single-cell RNA sequencing analysis within the same multiomics dataset. We show that epigenetic aging involves co-regulated changes as well as a major stochastic component, and this is consistent with transcriptional patterns. We further support the finding of stochastic epigenetic aging by direct tissue and single-cell DNAm analyses and modeling of aging DNAm trajectories with a stochastic process akin to radiocarbon decay. Finally, we describe a single-cell algorithm for the identification of co-regulated and stochastic CpG clusters showing consistent transcriptomic coordination patterns. Together, our analyses increase our understanding of the basis of epigenetic clocks and highlight potential opportunities for targeting aging and evaluating longevity interventions.

The impact of maternal smoking during pregnancy and the age of smoking initiation on incident dementia: A prospective cohort study.

INTRODUCTION: The impact of early-life tobacco exposure on dementia has remained unknown. METHODS: Using the UK Biobank, the associations of maternal smoking during pregnancy (MSDP) and age of smoking initiation (ASI) with the onset time of all-cause dementia were estimated with accelerated failure time models. The effects of MSDP and ASI on brain structure and their genetic correlation to Alzheimer's disease (AD) were analyzed. A Mendelian randomization (MR) analysis was conducted. RESULTS: The time ratios for smokers starting in childhood, adolescence, and adulthood (vs never smokers) were 0.87 (0.76 to 0.99), 0.92 (0.88 to 0.96), and 0.95 (0.89 to 1.01). MSDP and smoking in adolescence altered many brain regions, including the hippocampus. In genetic analysis, MSDP was genetically and causally linked to AD, and a younger ASI was genetically correlated to a higher AD risk. DISCUSSION: Early-life smoking accelerated dementia onset and was genetically correlated to AD. MSDP demonstrated genetic and causal linkage to AD risks. HIGHLIGHTS: Unlike the commonly used Cox proportional hazards model, this article uses a parametric survival analysis method - the accelerated failure model - to explore the relationship between exposure to onset time. It can be used as an alternative method when the proportional hazards assumption is not met. Genetic analyses including genetic correlation study and MR analysis and brain structure analyses were conducted to support our findings and explore the potential mechanisms. The study reveals the relationship between different smoking initiation periods and the onset time of dementia and shows that earlier smoking exposure has a more significant impact on dementia. It emphasizes the importance of preventing early smoking. In the future, more research focusing on the relationship between early exposure and dementia is called for to provide more detailed prevention measures for dementia that cover all age groups.

Latest advances on new promising molecular-based therapeutic approaches for Huntington's disease.

Huntington's disease (HD) is a devastating, autosomal-dominant inherited, neurodegenerative disorder characterized by progressive motor deficits, cognitive impairments, and neuropsychiatric symptoms. It is caused by excessive cytosine-adenine-guanine (CAG) trinucleotide repeats within the huntingtin gene (HTT). Presently, therapeutic interventions capable of altering the trajectory of HD are lacking, while medications for abnormal movement and psychiatric symptoms are limited. Numerous pre-clinical and clinical studies have been conducted and are currently underway to test the efficacy of therapeutic approaches targeting some of these mechanisms with varying degrees of success. In this review, we update the latest advances on new promising molecular-based therapeutic strategies for this disorder, including DNA-targeting techniques such as zinc-finger proteins, transcription activator-like effector nucleases, and CRISPR/Cas9; post-transcriptional huntingtin-lowering approaches such as RNAi, antisense oligonucleotides, and small-molecule splicing modulators; and novel methods to clear the mHTT protein, such as proteolysis-targeting chimeras. We mainly focus on the ongoing clinical trials and the latest pre-clinical studies to explore the progress of emerging potential HD therapeutics.

The characteristic and prognostic role of blood inflammatory markers in patients with Huntington's disease from China.

Objectives: This study aims to elucidate the role of peripheral inflammation in Huntington's disease (HD) by examining the correlation of peripheral inflammatory markers with clinical manifestations and disease prognosis. Methods: This investigation involved 92 HD patients and 92 matched healthy controls (HCs). We quantified various peripheral inflammatory markers and calculated their derived metrics including neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), lymphocyte-to-monocyte ratio (LMR), and systemic immune-inflammation index (SII). Clinical assessments spanning cognitive, motor, and disease severity were administered. Comparative analysis of inflammatory markers and clinical correlations between HD and controls was performed. Kaplan-Meier survival analysis and Cox regression model were used to assess the effect of inflammatory markers on survival. Results: The study revealed that HD patients had significantly reduced lymphocyte counts, and LMR. Conversely, NLR, PLR, and SII were elevated compared to HCs. Lymphocyte levels inversely correlated with the age of onset and monocyte levels inversely correlated with the UHDRS-total functional capacity (TFC) scores. After adjusting for age, sex, and CAG repeat length, lymphocyte count, NLR, PLR, and SII were significantly correlated with the progression rate of TFC scores. Elevated levels of white blood cells and monocytes were associated with an increased risk of disability and mortality in the HD cohort. Conclusion: Our findings indicate that HD patients display a distinct peripheral inflammatory profile with increased NLR, PLR, and SII levels compared to HCs. The peripheral inflammation appears to be linked with accelerated disease progression and decreased survival in HD.

Multi-omics characterization of partial chemical reprogramming reveals evidence of cell rejuvenation.

Partial reprogramming by cyclic short-term expression of Yamanaka factors holds promise for shifting cells to younger states and consequently delaying the onset of many diseases of aging. However, the delivery of transgenes and potential risk of teratoma formation present challenges for in vivo applications. Recent advances include the use of cocktails of compounds to reprogram somatic cells, but the characteristics and mechanisms of partial cellular reprogramming by chemicals remain unclear. Here, we report a multi-omics characterization of partial chemical reprogramming in fibroblasts from young and aged mice. We measured the effects of partial chemical reprogramming on the epigenome, transcriptome, proteome, phosphoproteome, and metabolome. At the transcriptome, proteome, and phosphoproteome levels, we saw widescale changes induced by this treatment, with the most notable signature being an upregulation of mitochondrial oxidative phosphorylation. Furthermore, at the metabolome level, we observed a reduction in the accumulation of aging-related metabolites. Using both transcriptomic and epigenetic clock-based analyses, we show that partial chemical reprogramming reduces the biological age of mouse fibroblasts. We demonstrate that these changes have functional impacts, as evidenced by changes in cellular respiration and mitochondrial membrane potential. Taken together, these results illuminate the potential for chemical reprogramming reagents to rejuvenate aged biological systems and warrant further investigation into adapting these approaches for in vivo age reversal.

Modulation of Dendritic Cell Function via Nanoparticle-Induced Cytosolic Calcium Changes.

Calcium nanoparticles have been investigated for applications, such as drug and gene delivery. Additionally, Ca2+ serves as a crucial second messenger in the activation of immune cells. However, few studies have systematically studied the effects of calcium nanoparticles on the calcium levels and functions within immune cells. In this study, we explore the potential of calcium nanoparticles as a vehicle to deliver calcium into the cytosol of dendritic cells (DCs) and influence their functions. We synthesized calcium hydroxide nanoparticles, coated them with a layer of silica to prevent rapid degradation, and further conjugated them with anti-CD205 antibodies to achieve targeted delivery to DCs. Our results indicate that these nanoparticles can efficiently enter DCs and release calcium ions in a controlled manner. This elevation in cytosolic calcium activates both the NFAT and NF-κB pathways, in turn promoting the expression of costimulatory molecules, antigen-presenting molecules, and pro-inflammatory cytokines. In mouse tumor models, the calcium nanoparticles enhanced the antitumor immune response and augmented the efficacy of both radiotherapy and chemotherapy without introducing additional toxicity. Our study introduces a safe nanoparticle immunomodulator with potential widespread applications in cancer therapy.

The role of type VI secretion system genes in antibiotic resistance and virulence in Acinetobacter baumannii clinical isolates.

Introduction: The type VI secretion system (T6SS) is a crucial virulence factor in the nosocomial pathogen Acinetobacter baumannii. However, its association with drug resistance is less well known. Notably, the roles that different T6SS components play in the process of antimicrobial resistance, as well as in virulence, have not been systematically revealed. Methods: The importance of three representative T6SS core genes involved in the drug resistance and virulence of A. baumannii, namely, tssB, tssD (hcp), and tssM was elucidated. Results: A higher ratio of the three core genes was detected in drug-resistant strains than in susceptible strains among our 114 A. baumannii clinical isolates. Upon deletion of tssB in AB795639, increased antimicrobial resistance to cefuroxime and ceftriaxone was observed, alongside reduced resistance to gentamicin. The ΔtssD mutant showed decreased resistance to ciprofloxacin, norfloxacin, ofloxacin, tetracycline, and doxycycline, but increased resistance to tobramycin and streptomycin. The tssM-lacking mutant showed an increased sensitivity to ofloxacin, polymyxin B, and furazolidone. In addition, a significant reduction in biofilm formation was observed only with the ΔtssM mutant. Moreover, the ΔtssM strain, followed by the ΔtssD mutant, showed decreased survival in human serum, with attenuated competition with Escherichia coli and impaired lethality in Galleria mellonella. Discussion: The above results suggest that T6SS plays an important role, participating in the antibiotic resistance of A. baumannii, especially in terms of intrinsic resistance. Meanwhile, tssM and tssD contribute to bacterial virulence to a greater degree, with tssM being associated with greater importance.

Hurdle or thruster: Glucose metabolism of T cells in anti-tumour immunity.

Glucose metabolism is essential for the activation, differentiation and function of T cells and proper glucose metabolism is required to maintain effective T cell immunity. Dysregulation of glucose metabolism is a hallmark of cancer, and the tumour microenvironment (TME2) can create metabolic barriers in T cells that inhibit their anti-tumour immune function. Targeting glucose metabolism is a promising approach to improve the capacity of T cells in the TME. The efficacy of common immunotherapies, such as immune checkpoint inhibitors (ICIs3) and adoptive cell transfer (ACT4), can be limited by T-cell function, and the treatment itself can affect T-cell metabolism. Therefore, understanding the relationship between immunotherapy and T cell glucose metabolism helps to achieve more effective anti-tumour therapy. In this review, we provide an overview of T cell glucose metabolism and how T cell metabolic reprogramming in the TME regulates anti-tumour responses, briefly describe the metabolic patterns of T cells during ICI and ACT therapies, which suggest possible synergistic strategies.

Streptococcus suis Serotype 2 Type IV Secretion Effector SspA-1 Induces Proinflammatory Cytokine Production via TLR2 Endosomal and Type I Interferon Signaling.

The subtilisin-like protease-1 (SspA-1) plays an important role in the pathogenesis of a highly virulent strain of Streptococcus suis 2. However, the mechanism of SspA-1-triggered excessive inflammatory response is still unknown. In this study, we demonstrated that activation of type I IFN signaling is required for SspA-1-induced excessive proinflammatory cytokine production. Further experiments showed that the TLR2 endosomal pathway mediates SspA-1-induced type I IFN signaling and the inflammatory response. Finally, we mapped the major signaling components of the related pathway and found that the TIR adaptor proteins Mal, TRAM, and MyD88 and the downstream activation of IRF1 and IRF7 were involved in this pathway. These results explain the molecular mechanism by which SspA-1 triggers an excessive inflammatory response and reveal a novel effect of type I IFN in S. suis 2 infection, possibly providing further insights into the pathogenesis of this highly virulent S. suis 2 strain.

Factors influencing cognitive function in patients with Huntington's disease from China: A cross-sectional clinical study.

BACKGROUND AND AIM: Huntington's disease (HD) is an autosomal dominant inherited neurodegenerative disorder caused by CAG repeats expansion. Cognitive decline contributes to the loss of daily activity in manifest HD. We aimed to examine the cognition status in a Chinese HD cohort and explore factors influencing the diverse cognitive domains. METHODS: A total of 205 participants were recruited in the study with the assessment by neuropsychological batteries, including the mini-mental state examination (MMSE), Stroop test, symbol digit modalities test (SDMT), trail making test (TMT), verbal fluency test (VFT), and Hopkins verbal learning test-revised, as well as motor and psychiatric assessment. Pearson correlation and multiple linear regression models were applied to investigate the correlation. RESULTS: Only 41.46% of patients had normal global function first come to our center. There was a significantly difference in MMSE, Stroop test, SDMT, TMT, and VFT across each stage of HD patients (p < .05). Apathy of PBA-s was correlated to MMSE, animal VFT and Stroop-interference tests performance. Severity of motor symptoms, functional capacity, age, and age of motor symptom onset were correlated to all neuropsychological scores, whereas education attainment and diagnostic delay were correlated to most neuropsychological scores except TMT. Severity of motor symptoms, functional capacity, and education attainment showed independent predicting effect (p < .05) in diverse cognitive domains. CONCLUSION: Cognitive impairment was very common in Chinese HD patients at the first visit and worse in the patients in advanced phase. The severity of motor symptoms and functional capacity were correlated to the diverse cognitive domains.

Neuro-11: a new questionnaire for the assessment of somatic symptom disorder in general hospitals.

Background: Somatic symptom disorder (SSD) commonly presents in general hospital settings, posing challenges for healthcare professionals lacking specialised psychiatric training. The Neuro-11 Neurosis Scale (Neuro-11) offers promise in screening and evaluating psychosomatic symptoms, comprising 11 concise items across three dimensions: somatic symptoms, negative emotions and adverse events. Prior research has validated the scale's reliability, validity and theoretical framework in somatoform disorders, indicating its potential as a valuable tool for SSD screening in general hospitals. Aims: This study aimed to establish the reliability, validity and threshold of the Neuro-11 by comparing it with standard questionnaires commonly used in general hospitals for assessing SSD. Through this comparative analysis, we aimed to validate the effectiveness and precision of the Neuro-11, enhancing its utility in clinical settings. Methods: Between November 2020 and December 2021, data were collected from 731 patients receiving outpatient and inpatient care at Shenzhen People's Hospital in China for various physical discomforts. The patients completed multiple questionnaires, including the Neuro-11, Short Form 36 Health Survey, Patient Health Questionnaire 15 items, Hamilton Anxiety Scale and Hamilton Depression Scale. Psychiatry-trained clinicians conducted structured interviews and clinical examinations to establish a gold standard diagnosis of SSD. Results: The Neuro-11 demonstrated strong content reliability and structural consistency, correlating significantly with internationally recognised and widely used questionnaires. Despite its brevity, the Neuro-11 exhibited significant correlations with other questionnaires. A test-retest analysis yielded a correlation coefficient of 1.00, Spearman-Brown coefficient of 0.64 and Cronbach's α coefficient of 0.72, indicating robust content reliability and internal consistency. Confirmatory factor analysis confirmed the validity of the three-dimensional structure (p<0.001, comparative fit index=0.94, Tucker-Lewis index=0.92, root mean square error of approximation=0.06, standardised root mean square residual=0.04). The threshold of the Neuro-11 is set at 10 points based on the maximum Youden's index from the receiver operating characteristic curve analysis. In terms of diagnostic efficacy, the Neuro-11 has an area under the curve of 0.67. Conclusions: (1) The Neuro-11 demonstrates robust associations with standard questionnaires, supporting its validity. It is applicable in general hospital settings, assessing somatic symptoms, negative emotions and adverse events. (2) The Neuro-11 exhibits strong content reliability and validity, accurately capturing the intended constructs. The three-dimensional structure demonstrates robust construct validity. (3) The threshold of the Neuro-11 is set at 10 points.

Targeting leucine-rich repeat serine/threonine-protein kinase 2 sensitizes pancreatic ductal adenocarcinoma to anti-PD-L1 immunotherapy.

Pancreatic ductal adenocarcinoma (PDAC) is not sensitive to immune checkpoint blockade therapy, and negative feedback of tumor immune evasion might be partly responsible. We isolated CD8+ T cells and cultured them in vitro. Proteomics analysis was performed to compare changes in Panc02 cell lines cultured with conditioned medium, and leucine-rich repeat kinase 2 (LRRK2) was identified as a differential gene. LRRK2 expression was related to CD8+ T cell spatial distribution in PDAC clinical samples and upregulated by CD8+ T cells via interferon gamma (IFN-γ) simulation in vitro. Knockdown or pharmacological inhibition of LRRK2 activated an anti-pancreatic cancer immune response in mice, which meant that LRRK2 acted as an immunosuppressive gene. Mechanistically, LRRK2 phosphorylated PD-L1 at T210 to inhibit its ubiquitination-mediated proteasomal degradation. LRRK2 inhibition attenuated PD-1/PD-L1 blockade-mediated, T cell-induced upregulation of LRRK2/PD-L1, thus sensitizing the mice to anti-PD-L1 therapy. In addition, adenosylcobalamin, the activated form of vitamin B12, which was found to be a broad-spectrum inhibitor of LRRK2, could inhibit LRRK2 in vivo and sensitize PDAC to immunotherapy as well, which potentially endows LRRK2 inhibition with clinical translational value. Therefore, PD-L1 blockade combined with LRRK2 inhibition could be a novel therapy strategy for PDAC.

The optimized carbapenem inactivation method for objective and accurate detection of carbapenemase-producing Acinetobacter baumannii.

The modified carbapenem inactivation method (mCIM) recommended by the Clinical and Laboratory Standards Institute is not applicable for detecting carbapenemases in Acinetobacter baumannii. Four currently reported phenotypic detection methods, namely, the modified Hodge test, the mCIM, the adjusted mCIM, and the simplified carbapenem inactivation method (sCIM), did not perform well in our 90 clinical A. baumannii isolates. Thus, the minimal inhibitory concentrations (MICs) of carbapenems and the existence and expression of carbapenemase-encoding genes were detected to explain the results. According to the E-test, which was more accurate than the VITEK 2 system, 80.0 and 41.1% were resistant to imipenem (IPM) and meropenem (MEM), respectively, and 14.4 and 53.3% exhibited intermediate resistance, respectively. Five ß-lactamase genes were found, of which blaOXA-51-like, blaTEM, and blaOXA-23-like were detected more frequently in 85 non-susceptible strains. The expression of blaOXA-23-like was positively correlated with the MIC values of IPM and MEM. Therefore, an improved approach based on the mCIM, designated the optimized CIM (oCIM), was developed in this study to detect carbapenemases more accurately and reproducibly. The condition was improved by evaluating the factors of A. baumannii inoculum, incubation broth volume, and MEM disk incubation time. Obvious high sensitivity (92.94%) and specificity (100.00%) were obtained using the oCIM, which was cost-effective and reproducible in routine laboratory work.

Multi-omics characterization of partial chemical reprogramming reveals evidence of cell rejuvenation.

Partial reprogramming by cyclic short-term expression of Yamanaka factors holds promise for shifting cells to younger states and consequently delaying the onset of many diseases of aging. However, the delivery of transgenes and potential risk of teratoma formation present challenges for in vivo applications. Recent advances include the use of cocktails of compounds to reprogram somatic cells, but the characteristics and mechanisms of partial cellular reprogramming by chemicals remain unclear. Here, we report a multi-omics characterization of partial chemical reprogramming in fibroblasts from young and aged mice. We measured the effects of partial chemical reprogramming on the epigenome, transcriptome, proteome, phosphoproteome, and metabolome. At the transcriptome, proteome, and phosphoproteome levels, we saw widescale changes induced by this treatment, with the most notable signature being an upregulation of mitochondrial oxidative phosphorylation. Furthermore, at the metabolome level, we observed a reduction in the accumulation of aging-related metabolites. Using both transcriptomic and epigenetic clock-based analyses, we show that partial chemical reprogramming reduces the biological age of mouse fibroblasts. We demonstrate that these changes have functional impacts, as evidenced by changes in cellular respiration and mitochondrial membrane potential. Taken together, these results illuminate the potential for chemical reprogramming reagents to rejuvenate aged biological systems and warrant further investigation into adapting these approaches for in vivo age reversal.

An Inflammatory Checkpoint Generated by IL1RN Splicing Offers Therapeutic Opportunity for KRAS-Mutant Intrahepatic Cholangiocarcinoma.

KRAS mutations are causally linked to protumor inflammation and are identified as driving factors in tumorigenesis. Here, using multiomics data gathered from a large set of patients, we showed that KRAS mutation was associated with a specific landscape of alternative mRNA splicing that connected to myeloid inflammation in intrahepatic cholangiocarcinoma (iCCA). Then, we identified a negative feedback mechanism in which the upregulation of interleukin 1 receptor antagonist (IL1RN)-201/203 due to alternative splicing confers vital anti-inflammatory effects in KRAS-mutant iCCA. In KRAS-mutant iCCA mice, both IL1RN-201/203 upregulation and anakinra treatment ignited a significant antitumor immune response by altering neutrophil recruitment and phenotypes. Furthermore, anakinra treatment synergistically enhanced anti-PD-1 therapy to activate intratumoral GZMB+ CD8+ T cells in KRAS-mutant iCCA mice. Clinically, we found that high IL1RN-201/203 levels in patients with KRAS-mutant iCCA were significantly associated with superior response to anti-PD-1 immunotherapy. SIGNIFICANCE: This work describes a novel inflammatory checkpoint mediated by IL1RN alternative splicing variants that may serve as a promising basis to develop therapeutic options for KRAS-mutant iCCA and other cancers. This article is featured in Selected Articles from This Issue, p. 2109.

Threat of soil formation rate to health of karst ecosystem.

Karst ecosystems are important to several billion people, so it is necessary to accurately diagnose and evaluate the health of these ecosystems for socioeconomic development; however, the existing evaluation methods have many limitations, so they cannot accurately evaluate the ecosystem health in karst areas. In particular, they ignore the influence and restriction of the soil formation rate on the ecosystem health. To this end, we established a new index to represent the actual health status of karst ecosystems. The soil formation rate was found to pose a threat to the health of 28 % of the world's karst ecosystems, covering an area of 594 km2. In addition, a dataset of global karst ecosystem health index values with a spatial resolution of about 8 km × 8 km from 2000 to 2014 was created, and the proportion of unhealthy areas was found to be as high as 75.91 %. This study highlights the contribution of the soil formation rate to karst ecosystem health and provides a new method and deeper scientific understanding for further accurate evaluation of karst ecosystem health, which can improve future ecosystem health research and social management.

Aberrant resting-state brain activity in Huntington's disease: A voxel-based meta-analysis.

Introduction: Functional neuroimaging could provide abundant information of underling pathophysiological mechanisms of the clinical triad including motor, cognitive and psychiatric impairment in Huntington's Disease (HD). Methods: We performed a voxel-based meta-analysis using anisotropic effect size-signed differential mapping (AES-SDM) method. Results: 6 studies (78 symptomatic HD, 102 premanifest HD and 131 healthy controls) were included in total. Altered resting-state brain activity was primarily detected in the bilateral medial part of superior frontal gyrus, bilateral anterior cingulate/paracingulate gyrus, left insula, left striatum, right cortico-spinal projections area, right inferior temporal gyrus area, right thalamus, right cerebellum and right gyrus rectus area. Premanifest and symptomatic HD patients showed different alterative pattern in the subgroup analyses. Discussion: The robust and consistent abnormalities in the specific brain regions identified in the current study could help to understand the pathophysiology of HD and explore reliable neuroimaging biomarkers for monitoring disease progression, or even predicting the onset of premanifest HD patients.

Effect of Fermentation Humidity on Quality of Congou Black Tea.

This study investigated the effect of different fermentation humidities (55%, 65%, 75%, 85% and 95%) on congou black tea quality and bioactivity. Fermentation humidity mainly affected the tea's appearance, aroma and taste quality. The tea fermented at low humidity (75% or below) showed a decrease in tightness, evenness and moistening degree, as well as a heavy grassy and greenish scent, plus a green, astringent and bitter taste. The tea fermented at a high humidity (85% or above) presented a sweet and pure aroma, as well as a mellow taste, plus an increase of sweetness and umami. With increasing fermentation humidity, the tea exhibited a drop in the content of flavones, tea polyphenols, catechins (EGCG, ECG) and theaflavins (TF, TF-3-G), contrasted by a rise in the content of soluble sugars, thearubigins and theabrownins, contributing to the development of a sweet and mellow taste. Additionally, the tea showed a gradual increase in the total amount of volatile compounds and in the content of alcohols, alkanes, alkenes, aldehydes, ketones and acids. Moreover, the tea fermented at a low humidity had stronger antioxidant activity against 2, 2-Diphenyl-1-picrylhydrazyl (DPPH) and a higher inhibiting capability on the activities of α-amylase and α-glucosidase. Overall results indicated the desirable fermentation humidity of congou black tea should be 85% or above.

Probiotic Lactobacillus Species and Their Biosurfactants Eliminate Acinetobacter baumannii Biofilm in Various Manners.

Acinetobacter baumannii is a critical biofilm-forming pathogen that has presented great challenges in the clinic due to multidrug resistance. Thus, new methods of intervention are needed to control biofilm-associated infections. In this study, among three tested Lactobacillus species, Lactobacillus rhamnosus showed significant antimaturation and antiadherence effects against A. baumannii biofilm. Lactic acid (LA) and acetic acid (AA) were the most effective antibiofilm biosurfactants (BSs) produced by L. rhamnosus. This antibiofilm phenomenon produced by LA and AA was due to the strong bactericidal effect, which worked from very early time points, as determined by colony enumeration and confocal laser scanning microscope. The cell destruction of A. baumannii appeared in both the cell envelope and cytoplasm. A discontinuous cell envelope, the leakage of cell contents, and the increased extracellular activity of ATPase demonstrated the disruption of the cell membrane by LA and AA. These effects also demonstrated the occurrence of protein lysis. In addition, bacterial DNA interacted with and was damaged by LA and AA, resulting in significantly reduced expression of biofilm and DNA repair genes. The results highlight the possibility and importance of using probiotics in clinical prevention. Probiotics can be utilized as novel biocides to block and decrease biofilm formation and microbial contamination in medical equipment and during the treatment of infections. IMPORTANCE A. baumannii biofilm is a significant virulence factor that causes the biofilm colonization of invasive illnesses. Rising bacterial resistance to synthetic antimicrobials has prompted researchers to look at natural alternatives, such as probiotics and their derivatives. In this study, L. rhamnosus and its BSs (LA and AA) demonstrated remarkable antibiofilm and antimicrobial characteristics, with a significant inhibitory effect on A. baumannii. These effects were achieved by several mechanisms, including the disruption of the cell envelope membrane, protein lysis, reduced expression of biofilm-related genes, and destruction of bacterial DNA. The results provide support for the possibility of using probiotics and their derivatives in the clinical prevention and therapy of A. baumannii infections.