TLR2 and TLR4 activity in monocytes and macrophages after exposure to amoxicillin, ciprofloxacin, doxycycline and erythromycin

Lactobacillus acidophilus (strain Scav) postbiotic metabolites reduce infection and modulate inflammation in an in vivo model of Pseudomonas aeruginosa wound infection

AIMS

This study assessed the antibacterial, antibiofilm, and immunomodulatory activity of Lactobacillus acidophilus (strain Scav) postbiotic (LaP) in a mouse model of Pseudomonas aeruginosa wound infection and evaluated the bioactive components of the LaP.

METHODS AND RESULTS

LaP was tested for Pseudomonas aeruginosa clearance and immunomodulatory activity during wound infection. We show that LaP applied 1 h after infection reduced tissue bacterial burden within 24 h, and this reduction persisted for 5 days. Ciprofloxacin given once at the exact same time did not reduce bacteria load as compared to vehicle controls. LaP reduced plasma IL-6 and MCP-1 levels after 5 days. Wound tissue IL-6 and MCP-1 levels were increased in infected vehicle mice at 5 days, but tissues from LaP-treated mice were similar to sham controls. LaP increased tissue IL-10 (antiinflammatory cytokine) levels. Ciprofloxacin decreased plasma and tissue IL-6 compared to vehicle controls but did not affect MCP-1 or IL-10 levels. To elucidate antibacterial and antibiofilm metabolite(s) in LaP, fractionation followed by Ps. aeruginosa antagonistic activity assays were performed. This was followed by liquid chromatography coupled to mass spectrometry (LCMS) analysis. Our analyses identified a low molecular weight, polar molecule, which had both antibacterial and antibiofilm activity.

CONCLUSIONS

Lactobacillus acidophilus secretes an antibacterial and antibiofilm metabolite that reduced pathogen burden and resolved systemic inflammation in a Pseudomonas aeruginosa wound infection model.

Development and internal validation of a nomogram for predicting recurrent respiratory tract infections in children

OBJECTIVE

This study aimed to develop and internally validate a nomogram in predicting the risk of recurrent respiratory tract infection (RRTI) in children.

METHODS

A retrospective analysis was performed, involving 150 children with RRTI and 151 healthy controls, aged 0-14 years, admitted to or selected from the Pediatric Department of Yixing Hospital of Traditional Chinese Medicine between June 2022 and June 2023. Data were gathered through a comprehensive questionnaire survey on risk factors associated with RRTI. The dataset was randomly divided into a training cohort (n = 211) and a validation cohort (n = 90) in a 7:3 ratio. Significant variables were selected using LASSO regression in the training cohort to construct the nomogram, the performance of which was evaluated through Receiver Operating Characteristic (ROC) curves, calibration plots, and Decision Curve Analysis (DCA).

RESULTS

The LASSO regression identified five predictors in the training cohort: picky eating, age at first antibiotic use, antibiotic use within the previous year, allergic conditions, secondhand smoke exposure. Based on them, the nomogram exhibited an excellent discriminative ability, with an AUC of 0.902 (95 % CI: 0.860-0.944) and a C-index of 0.902 in the training cohort. The validation cohort showed an AUC of 0.826 (95 % CI: 0.742-0.909) and a C-index of 0.826, confirming a high predictive accuracy. Calibration plots showed close alignment with the ideal reference line, and DCA indicated a significant clinical net benefit.

CONCLUSION

Our nomogram can efficiently predict RRTI risk in children, thereby providing a personalized and graphical tool for early identification and intervention.

Immunostimulatory effects of isomalto/malto-polysaccharides via TLR2 and TLR4 in preventing doxycycline-induced cytokine loss

Isomalto/malto-polysaccharides (IMMPs) are α-glucans with prebiotic potential used as food ingredients. However, their ability to exert direct cellular effects remains unknown. IMMPs may enhance immunity by activating toll-like receptors (TLRs), key for defense against pathogens. Doxycycline is an antibiotic that requires an effective immune function but paradoxically has immune-attenuating effects by reducing TLR2 activity, potentially increasing antibiotic needs. We hypothesize that IMMPs are recognized by various cell surface TLRs, leading to the activation of the NF-κB signaling pathway. Furthermore, IMMPs' immune-stimulating effect could prevent the doxycycline-induced reduction of TLR2 activity in immune cells. IMMPs activated TLR2, increasing NF-κB signaling by 3.42- and 6.37-fold at 1 and 2 mg/mL, respectively. TLR4 activation increased 5.47-, 7.39-, and 8.34-fold at 0.5, 1, and 2 mg/mL. IMMPs enhanced IL-8, TNFα, and IL1-RA production in THP-1 monocytes. Additionally, preincubation of macrophages with IMMPs enhanced cytokine production and partially prevented doxycycline-induced cytokine reduction in response to TLR2 activation. Molecular docking analyses support IMMPs and doxycycline binding to these TLRs. These findings suggest that IMMPs stimulate immunity via TLR2 and TLR4, partially mitigating doxycycline's adverse effects. This provides a dietary strategy to enhance pathogen clearance, reduce antibiotic needs, and support immune health.

Anti‑obesity and immunostimulatory activity of Chrysosplenium flagelliferum in mouse preadipocytes 3T3‑L1 cells and mouse macrophage RAW264.7 cells

Chrysosplenium flagelliferum (CF) is known for its anti-inflammatory, antioxidant and antibacterial activities. However, there is a lack of research on its other pharmacological properties. In the present study, the bifunctional roles of CF in 3T3-L1 and RAW264.7 cells were investigated, focusing on its anti-obesity and immunostimulatory effects. In 3T3-L1 cells, CF effectively mitigated the accumulation of lipid droplets and triacylglycerol. Additionally, CF downregulated the peroxisome proliferator-activated receptor (PPAR)-γ and CCAAT/enhancer-binding protein α protein levels; however, this effect was impeded by the knockdown of β-catenin using β-catenin-specific small interfering RNA. Consequently, CF-mediated inhibition of lipid accumulation was also decreased. CF increased the protein levels of adipose triglyceride lipase and phosphorylated hormone-sensitive lipase, while decreasing those of perilipin-1. Moreover, CF elevated the protein levels of phosphorylated AMP-activated protein kinase and PPARγ coactivator 1-α. In RAW264.7 cells, CF enhanced the production of pro-inflammatory mediators, such as nitric oxide (NO), inducible NO synthase, interleukin (IL)-1β, IL-6 and tumor necrosis factor-α, and increased their phagocytic capacities. Inhibition of Toll-like receptor (TLR)-4 significantly reduced the effects of CF on the production of pro-inflammatory mediators and phagocytosis, indicating its crucial role in facilitating these effects. CF-induced increase in the production of pro-inflammatory mediators was controlled by the activation of c-Jun N-terminal kinase (JNK) and nuclear factor (NF)-κB pathways, and TLR4 inhibition attenuated the phosphorylation of these kinases. The results of the pesent study suggested that CF inhibits lipid accumulation by suppressing adipogenesis and inducing lipolysis and thermogenesis in 3T3-L1 cells, while stimulating macrophage activation via the activation of JNK and NF-κB signaling pathways mediated by TLR4 in RAW264.7 cells. Therefore, CF simultaneously exerts both anti-obesity and immunostimulatory effects.

TLR2 and TLR4 Are Expressed in Epiretinal Membranes: Possible Links with Vitreous Levels of Complement Fragments and DAMP-Related Proteins

Previous studies reported the expression of toll-like receptors (TLRs), merely TLR2 and TLR4, and complement fragments (C3a, C5b9) in vitreoretinal disorders. Other than pathogens, TLRs can recognize endogenous products of tissue remodeling as damage-associated molecular pattern (DAMPs). The aim of this study was to confirm the expression of TLR2 and TLR4 in the fibrocellular membranes and vitreal fluids (soluble TLRs) of patients suffering of epiretinal membranes (ERMs) and assess their association with disease severity, complement fragments and inflammatory profiles. Twenty (n = 20) ERMs and twelve (n = 12) vitreous samples were collected at the time of the vitrectomy. Different severity-staged ERMs were processed for: immunolocalization (IF), transcriptomic (RT-PCR) and proteomics (ELISA, IP/WB, Protein Chip Array) analysis. The investigation of targets included TLR2, TLR4, C3a, C5b9, a few selected inflammatory biomarkers (Eotaxin-2, Rantes, Vascular Endothelial Growth Factor (VEGFA), Vascular Endothelial Growth Factor receptor (VEGFR2), Interferon-γ (IFNγ), Interleukin (IL1β, IL12p40/p70)) and a restricted panel of matrix enzymes (Matrix metalloproteinases (MMPs)/Tissue Inhibitor of Metallo-Proteinases (TIMPs)). A reduced cellularity was observed as function of ERM severity. TLR2, TLR4 and myD88 transcripts/proteins were detected in membranes and decreased upon disease severity. The levels of soluble TLR2 and TLR4, as well as C3a, C5b9, Eotaxin-2, Rantes, VEGFA, VEGFR2, IFNγ, IL1β, IL12p40/p70, MMP7 and TIMP2 levels were changed in vitreal samples. Significant correlations were observed between TLRs and complement fragments and between TLRs and some inflammatory mediators. Our findings pointed at TLR2 and TLR4 over-expression at early stages of ERM formation, suggesting the participation of the local immune response in the severity of disease. These activations at the early-stage of ERM formation suggest a potential persistence of innate immune response in the early phases of fibrocellular membrane formation.

A novel 12-membered ring non-antibiotic macrolide EM982 attenuates cytokine production by inhibiting IKKβ and IκBα phosphorylation

Antimicrobial resistance poses a serious threat to human health worldwide and its incidence continues to increase owing to the overuse of antibiotics and other factors. Macrolide antibiotics such as erythromycin (EM) have immunomodulatory effects in addition to their antibacterial activity. Long-term, low-dose administration of macrolides has shown clinical benefits in treating non-infectious inflammatory respiratory diseases. However, this practice may also increase the emergence of drug-resistant bacteria. In this study, we synthesized a series of EM derivatives, and screened them for two criteria: (i) lack of antibacterial activity and (ii) ability to suppress tumor necrosis factor-α (TNF-α) production in THP-1 cells stimulated with lipopolysaccharide. Among the 37 synthesized derivatives, we identified a novel 12-membered ring macrolide EM982 that lacked antibacterial activity against Staphylococcus aureus and suppressed the production of TNF-α and other cytokines. The effects of EM982 on Toll-like receptor 4 (TLR4) signaling were analyzed using a reporter assay and Western blotting. The reporter assay showed that EM982 suppressed the activation of transcription factors, NF-κB and/or activator protein 1 (AP-1), in HEK293 cells expressing human TLR4. Western blotting showed that EM982 inhibited the phosphorylation of both IκB kinase (IKK) β and IκBα, which function upstream of NF-κB, whereas it did not affect the phosphorylation of p38 mitogen-activated protein kinase, extracellular signal-regulated kinase, and c-Jun N-terminal kinase, which act upstream of AP-1. These results suggest that EM982 suppresses cytokine production by inhibiting phosphorylation of IKKβ and IκBα, resulting in the inactivation of NF-κB.

RNA-seq transcriptome analysis provides new insights into the negative effects of tannic acid on the intestinal function of Brandt's voles (Lasiopodomys brandtii)

Tannic acid (TA), a significant plant secondary metabolite, is contained in the daily food of Brandt's voles. Its adverse effect on gut function has been shown in earlier research, but the underlying molecular mechanisms remain uncertain. In this study, male Brandt's vole (13 weeks old) were divided into two groups and given 0 (control) or 1,200 (TA-treated) mg•kg-1 TA for 18 days. Then RNA sequencing was used to conduct a thorough transcriptome analysis on the duodenum, jejunum, and ileum of Brandt's voles. Results showed that TA significantly increased serum total cholesterol concentration (P < 0.05) and decreased the nutrient digestibility (P < 0.05) of Brandt's voles. Furthermore, there were 174 differentially expressed genes (DEGs) in the duodenum, 96 DEGs in the jejunum, and 88 DEGs in the ileum between the control and TA-treated groups. Enrichment analysis revealed that many genes associated with bile secretion, fat digestion and absorption, innate immune response, and tight junction such as ABCG2, ABCG8, PEAK1, and IFR2, etc. were altered after TA treatment, which were verified by quantitative real-time PCR. These findings suggested that TA can change the expression of intestinal genes, thereby, altering nutrition metabolism and immunological function, eventually hindering the growth of Brandt's voles. The results of this study provide a theoretical basis for explaining how TA affects the gut function of Brandt's voles at the molecular level.

Doxycycline-Loaded Calcium Phosphate Nanoparticles with a Pectin Coat Can Ameliorate Lipopolysaccharide-Induced Neuroinflammation Via Enhancing AMPK

Neuroinflammation occurs in response to different injurious triggers to limit their hazardous effects. However, failure to stop this process can end in multiple neurological diseases. Doxycycline (DX) is a tetracycline, with potential antioxidant and anti-inflammatory properties. The current study tested the effects of free DX, DX-loaded calcium phosphate (DX@CaP), and pectin-coated DX@CaP (Pec/DX@CaP) nanoparticles on the lipopolysaccharide (LPS)-induced neuroinflammation in mice and to identify the role of adenosine monophosphate-activated protein kinase (AMPK) in this effect. The present study was conducted on 48 mice, divided into 6 groups, eight mice each. Group 1 (normal control), Group 2 (blank nanoparticles-treated), Group 3 (LPS (untreated)), Groups 4, 5, and 6 received LPS, then Group 4 received free DX, Group 5 received DX-loaded calcium phosphate nanoparticles (DX@CaP), and Group 6 received DX-loaded calcium phosphate nanoparticles with a pectin coat (Pec/DX@CaP). At the end of the experimentation period, behavioral tests were carried out. Then, mice were sacrificed, and brain tissue was extracted and used for histological examination, and assessment of interleukin-6 positive cells in different brain areas, in addition to biochemical measurement of SOD activity, TLR-4, AMPK and Nrf2. LPS can induce prominent neuroinflammation. Treatment with (Pec/DX@CaP) can reverse most behavioral, histopathological, and biochemical changes caused by LPS. The findings of the current study suggest that (Pec/DX@CaP) exerts a significant reverse of LPS-induced neuroinflammation by enhancing SOD activity, AMPK, and Nrf2 expression, in addition to suppression of TLR-4.

Crystal type, chain length and polydispersity impact the resistant starch type 3 immunomodulatory capacity via Toll-like receptors

Food ingredients that can activate and improve immunological defense, against e.g., pathogens, have become a major field of research. Resistant starches (RSs) can resist enzymes in the upper gastrointestinal (GI) tract and induce health benefits. RS-3 physicochemical characteristics such as chain length (DP), A- or B-type crystal, and polydispersity index (PI) might be crucial for immunomodulation by activating human toll-like receptors (hTLRs). We hypothesize that crystal type, DP and PI, alone or in combination, impact the recognition of RS-3 preparations by hTLRs leading to different RS-3 immunomodulatory effects. We studied the activation of hTLR2, hTLR4, and hTLR5 by 0.5, 1 and 2 mg/mL of RS-3. We found strong activation of hTLR2-dependent NF-kB activation with PI <1.25, DP 18 as an A- or B-type crystal. At different doses, NF-kB activation was increased from 6.8 to 7.1 and 10-fold with A-type and 6.2 to 10.2 and 14.4-fold with B-type. This also resulted in higher cytokine production in monocytes. Molecular docking, using amylose-A and B, demonstrated that B-crystals bind hTLR2 promoting hTLR2-1 dimerization, supporting the stronger effects of B-type crystals. Immunomodulatory effects of RS-3 are predominantly hTLR2-dependent, and activation can be tailored by managing crystallinity, chain length, and PI.

The effect of early administration of antibiotics or feeding a diet containing a coccidiostat on inflammatory responses and the morphological structure of selected organs of the immune system in young meat-type turkeys

It was assumed that early administration of enrofloxacin or doxycycline may impair immune function and alter the morphology of organs of the immune system in turkeys, and that diets containing the coccidiostat monensin, an ionophore antibiotic, can exert similar effects. The aim of this study was to determine whether early antibiotic administration or feeding a diet containing a coccidiostat affect immune function in young turkeys. The experiment had a completely randomized design, with 8 groups (a total of 3,080 one-day-old turkeys), 7 replicate pens per group and 55 birds per pen. The experiment had a 2-factorial design, with 4 treatments (C-control, M-monensin, E-enrofloxacin, and D-doxycycline) and 2 groups of birds (vaccinated and unvaccinated) per treatment. Control group birds did not receive the coccidiostat or antibiotics. Group M was administered monensin at 90 mg/kg feed for the first 5 d of life, group E received enrofloxacin at 10 mg/kg BW, added to drinking water, for the first 5 d of life, and group D received doxycycline at 50 mg/kg BW, added to drinking water, for the first 5 d of life. One-day old turkeys from groups C+, M+, E+, and D+ were administered live-attenuated vaccines against turkey rhinotracheitis (TRT) (Poulvac TRT; Zoetis, Parsippany, NJ) and Newcastle disease (ND) (Nobilis ND clone 30; Merck, Rahway, NJ) by coarse spray; 28-day-old birds were administered a subcutaneously injected inactivated vaccine against Ornithobacterium rhinotracheale (ORT) (Ornitin, Phibro, Poland). Turkeys from groups C-, M-, E-, and D- were not vaccinated. It was found that early administration of enrofloxacin or doxycycline, or feeding a diet containing monensin, did not weaken the immune system of turkeys. The administration of monensin, in particular when combined with vaccination, was least effective in inhibiting inflammatory responses. Histological changes in immunocompetent organs (fatty degeneration) were also most severe in birds receiving monensin, followed by those administered doxycycline and enrofloxacin. The observed changes were exacerbated by vaccination.

Tigecycline reduces tumorigenesis in colorectal cancer via inhibition of cell proliferation and modulation of immune response

BACKGROUND

and Purpose: Colorectal cancer (CRC) is one of the cancers with the highest incidence in which APC gene mutations occur in almost 80% of patients. This mutation leads to β-catenin aberrant accumulation and an uncontrolled proliferation. Apoptosis evasion, changes in the immune response and microbiota composition are also events that arise in CRC. Tetracyclines are drugs with proven antibiotic and immunomodulatory properties that have shown cytotoxic activity against different tumor cell lines.

EXPERIMENTAL APPROACH

The effect of tigecycline was evaluated in vitro in HCT116 cells and in vivo in a colitis-associated colorectal cancer (CAC) murine model. 5-fluorouracil was assayed as positive control in both studies.

KEY RESULTS

Tigecycline showed an antiproliferative activity targeting the Wnt/β-catenin pathway and downregulating STAT3. Moreover, tigecycline induced apoptosis through extrinsic, intrinsic and endoplasmic reticulum pathways converging on an increase of CASP7 levels. Furthermore, tigecycline modulated the immune response in CAC, reducing the cancer-associated inflammation through downregulation of cytokines expression. Additionally, tigecycline favored the cytotoxic activity of cytotoxic T lymphocytes (CTLs), one of the main immune defenses against tumor cells. Lastly, the antibiotic reestablished the gut dysbiosis in CAC mice increasing the abundance of bacterial genera and species, such as Akkermansia and Parabacteroides distasonis, that act as protectors against tumor development. These findings resulted in a reduction of the number of tumors and an amelioration of the tumorigenesis process in CAC.

CONCLUSION AND IMPLICATIONS

Tigecycline exerts a beneficial effect against CRC supporting the use of this antibiotic for the treatment of this disease.

Antimicrobial resistance and outcome in the critically ill patient: An opinion paper

Antimicrobial resistance (AMR) is associated with increased mortality and resources consumption in critically ill patients. However, the causality of AMR in this mortality remains unclear. This opinion paper aims to overview the effects of multidrug resistant (MDR) pathogens on the outcomes of critically ill patients, considering different variables as appropriateness of empirical antimicrobial therapy, severity of sepsis, comorbid conditions and frailty. Large studies based on national database associated MDR and increased mortality in critically ill patients. However, the patients carrying MDR pathogens, as compared with those carrying non-MDR pathogens, are those with co-morbid conditions, high risk of frailty and invasive procedures. In addition, inappropriate empirical antibiotics are more often used in these patients as well as withholding and withdrawing of life-sustained therapy. Future studies on AMR should report the rate of appropriateness of empirical antimicrobial therapy, withholding and withdrawing of life-sustained therapy.

Early antibiotics and risk for necrotizing enterocolitis in premature infants: A narrative review

While prompt initiation of antibiotics at birth due to concerns for early onset sepsis is common, it often leads to many preterm infants being exposed to treatment despite negative blood cultures. Such exposure to early antibiotics can impact the developing gut microbiome putting infants at increased risk of several diseases. Necrotizing enterocolitis (NEC), a devastating inflammatory bowel disease that affects preterm infants, is among the most widely studied neonatal disease that has been linked to early antibiotics. While some studies have demonstrated an increased risk of NEC, other studies have demonstrated seemingly contrary findings of decreased NEC with early antibiotics. Studies using animal models have also yielded differing findings of benefit vs. harm of early antibiotic exposure on subsequent NEC susceptibility. We thus sought to conduct this narrative review to help clarify the relationship between early antibiotics exposure and future risk of NEC in preterm infants. Our objectives are to: (1) summarize findings from human and animal studies that investigated the relationship between early antibiotics and NEC, (2) highlight important limitations of these studies, (3) explore potential mechanisms that can explain why early antibiotics may increase or decrease NEC risk, and (4) identify future directions for research.