Spirulina maxima Derived Pectin Nanoparticles Enhance the Immunomodulation, Stress Tolerance, and Wound Healing in Zebrafish.

In this study, Spirulina maxima derived pectin nanoparticles (SmPNPs) were synthesized and multiple biological effects were investigated using in vitro and in vivo models. SmPNPs were not toxic to Raw 264.7 cells and zebrafish embryos up to 1 mg/mL and 200 µg/mL, respectively. SmPNPs upregulated Il 10, Cat, Sod 2, Def 1, Def 2, and Muc 1 in Raw 264.7 cells and tlr2, tlr4b, tlr5b, il1ß, tnfα, cxcl8a, cxcl18b, ccl34a.4, ccl34b.4, muc5.1, muc5.2, muc5.3, hamp, cstd, hsp70, cat, and sod1 in the larvae and adult zebrafish, suggesting immunomodulatory activity. Exposure of larvae to SmPNPs followed by challenge with pathogenic bacterium Aeromonas hydrophila resulted a two-fold reduction of reactive oxygen species, indicating reduced oxidative stress compared to that in the control group. The cumulative percent survival of larvae exposed to SmPNPs (50 µg/mL) and adults fed diet supplemented with SmPNPs (4%) was 53.3% and 76.7%, respectively. Topical application of SmPNPs on adult zebrafish showed a higher wound healing percentage (48.9%) compared to that in the vehicle treated group (38.8%). Upregulated wound healing markers (tgfß1, timp2b, mmp9, tnfα, il1ß,ccl34a.4, and ccl34b.4), enhanced wound closure, and restored pigmentation indicated wound healing properties of SmPNPs. Overall, results uncover the multiple bioactivities of SmPNPs, which could be a promising biocompatible candidate for broad range of aquatic and human therapies.

Spirulina maxima derived marine pectin promotes the in vitro and in vivo regeneration and wound healing in zebrafish.

Purified bioactive components of marine algae have shown great pharmaceutical and biomedical potential, including wound healing activity. However, the activity of Spirulina maxima is the least documented with regard to wound healing potential. In the present study, we investigated the regenerative and wound healing activities of a Spirulina (Arthrospira) maxima based pectin (SmP) using in vitro human dermal fibroblasts (HDFs) and in vivo zebrafish model. SmP treated (12.5-50 µg/mL) HDFs showed increased cell proliferation by 20-40% compared to the untreated HDFs. Moreover, in vitro wound healing results in HDFs demonstrated that SmP decreased the open wound area % in concentration-dependent manner at 12.5 (32%) and 25 µg/mL (12%) compared to the control (44%). Further, zebrafish larvae displayed a greater fin regenerated area in the SmP exposed group at 25 (0.48 mm2) and 50 µg/mL (0.51 mm2), whereas the untreated group had the lowest regenerated area (0.40 mm2) at 3 days post amputation. However, fin regeneration was significantly (P < 0.001) higher only in the SmP treated group at 50 µg/mL. Furthermore, the open skin wound healing % in adult zebrafish was significantly higher (P < 0.05) after topical application (600 µg/fish) of SmP (46%) compared to the control (38%). Upregulation of genes such as tgfß1, timp2b, mmp9, tnf-α, and il-1ß, and chemokines such as cxcl18b, ccl34a.4, and ccl34b.4, in the muscle and kidney tissues of SmP treated fish compared to the respective control group was demonstrated using qRT-PCR. Histological analysis results further supported the rapid epidermal growth and tissue remodeling in SmP treated fish, suggesting that SmP exerts positive effects associated with wound healing. Therefore, SmP can be considered a potential regenerative and wound healing agent.

Marine Microalgae, Spirulina maxima-Derived Modified Pectin and Modified Pectin Nanoparticles Modulate the Gut Microbiota and Trigger Immune Responses in Mice.

This study evaluated the modulation of gut microbiota, immune responses, and gut morphometry in C57BL/6 mice, upon oral administration of S. maxima-derived modified pectin (SmP, 7.5 mg/mL) and pectin nanoparticles (SmPNPs; 7.5 mg/mL). Metagenomics analysis was conducted using fecal samples, and mice duodenum and jejunum were used for analyzing the immune response and gut morphometry, respectively. The results of metagenomics analysis revealed that the abundance of Bacteroidetes in the gut increased in response to both modified SmP and SmPNPs (75%) as compared with that in the control group (66%), while that of Firmicutes decreased in (20%) as compared with that in the control group (30%). The mRNA levels of mucin, antimicrobial peptide, and antiviral and gut permeability-related genes in the duodenum were significantly (p < 0.05) upregulated (> 2-fold) upon modified SmP and SmPNPs feeding. Protein level of intestinal alkaline phosphatase was increased (1.9-fold) in the duodenum of modified SmPNPs feeding, evidenced by significantly increased goblet cell density (0.5 ± 0.03 cells/1000 µm2) and villi height (352 ± 10 µm). Our results suggest that both modified SmP and SmPNPs have the potential to modulate gut microbial community, enhance the expression of immune related genes, and improve gut morphology.

Novel pectin isolated from Spirulina maxima enhances the disease resistance and immune responses in zebrafish against Edwardsiella piscicida and Aeromonas hydrophila.

In this study, we demonstrate the enhanced disease resistance and positive immunomodulation of novel pectin isolated from Spirulina maxima (SmP) in zebrafish model. Zebrafish larvae exposed to SmP had significantly (p < 0.05) higher cumulative percent survival (CPS) at 25 (44.0%) and 50 µg/mL (67.0%) against Edwardsiella piscicida compared to the control. However, upon Aeromonas hydrophila challenge, SmP exposed larvae at 50 µg/mL had slightly higher CPS (33.3%) compared to control group (26.7%). SmP supplemented zebrafish exhibited the higher CPS against E. piscicida (93.3%) and A. hydrophila (60.0%) during the early stage of post-infection (<18 hpi). qRT-PCR results demonstrated that exposing (larvae) and feeding (adults) of SmP, drive the modulation of a wide array of immune response genes. In SmP exposed larvae, up-regulation of the antimicrobial enzyme (lyz: 3.5-fold), mucin (muc5.1: 2.84, muc5.2: 2.11 and muc5.3: 2.40-fold), pro-inflammatory cytokines (il1ß: 1.79-fold) and anti-oxidants (cat: 2.87 and sod1: 1.82-fold) were identified. In SmP fed adult zebrafish (gut) showed >2-fold induced pro-inflammatory cytokine (il1ß) and chemokines (cxcl18b, ccl34a.4 and ccl34b.4). Overall results confirmed the positive modulation of innate immune responses in larval stage and it could be the main reason for developing disease resistance against E. piscicida and A. hydrophila. Thus, non-toxic, natural and biodegradable SmP could be considered as the potential immunomodulatory agent for sustainable aquaculture.

Candida albicans Infection Model in Zebrafish (Danio rerio) for Screening Anticandidal Drugs.

BACKGROUND: Candida albicans is an opportunistic fungal pathogen which causes systemic infections in human. In this study, C. albicans infection model was developed in zebrafish to understand the host-pathogen interactions for straightforward anticandidal drug screening. METHODS: To develop the infection, 1 × 106 cells of C. albicans suspended in phosphate-buffered saline were deposited in zebrafish dorsal muscle by manually operated syringe. The infection progression was externally assessed by a scale of wound-healing events, based on visible changes of yeast deposited in the muscle tissues. Chemotherapy was carried out with known antifungal drugs (fluconazole, nystatin, and amphotericin B) and a potential antifungal agent, chitosan silver nanocomposites (CAgNC), after the infection as direct exposure in the water. Histopathological analysis was performed to identify the pathogen virulence and the host-pathogen interaction during the infection. RESULTS: The light microscopic observations and histopathological analysis revealed the yeast-hyphae transition at the site of infection (at 72 hpi) and progression of the infection in the host tissues. The larval survival rate under fluconazole (up to 80 µg mL-1) and nystatin (up to 20 µg mL-1) was > 90% and for CAgNC it was 40% at 36 h post-exposure (hpe). The infection progression was suppressed with the fungicidal treatments. Among inflammatory genes, il-1ß has been highly upregulated (14.68-fold) at 24 h post infection (hpi). Both il-1ß and tnf-α were moderately upregulated in infected fish gills at 72 hpi. Among the C. albicans antioxidant genes, cat1 and sod2 have been upregulated during the infection, and relative expression folds were increased from low to moderate levels with the time. DISCUSSION: We demonstrate the approach for the development of artificial infection model of zebrafish with C. albicans. By this mini vertebrate zebrafish model, researchers will be able to study novel anticandidal compounds in vivo with respect to the host, pathogen, and their interactions.

In vitro and in vivo antifungal efficacy of plant based lawsone against Fusarium oxysporum species complex.

Fusarium oxysporum is an ascomycete facultative fungus which generally affects to plants. However, it is recently known as a serious emerging opportunistic pathogen of human and other animals. F. oxysporum shows broad resistance to commonly used antifungal agents and therefore development of alternative therapeutic agents is required. In this study, we investigated the antifungal efficacy of plant based natural lawsone against pathogenic F. oxysporum. Antifungal susceptibility test determined the concentration dependent growth inhibition of lawsone against F. oxysporum with minimum inhibitory concentration (MIC) at 100µg/mL. Ultra-structural analysis indicates the prominent damage on cell wall of the mycelium after lawsone treatment, and suggests that it could increase the membrane permeability and disintegration of cells leading to cellular death. Propidium iodide (PI) uptake assay results showed the higher level of cell death in lawsone treated F. oxysporum which further confirms the loss of plasma membrane integrity. Also, detection of reactive oxygen species (ROS) using DCFH-DA has clearly indicated that lawsone (100µg/mL) can induce the ROS level in the filaments of F. oxysporum. MTT assay results showed the loss of viability and germination capacity of F. oxysporum spores by lawsone in concentration dependent manner. Moreover, lawsone treatment induced the mRNA expression of two autophagy related genes (ATG1 and ATG8) indicating that lawsone may activate the autophagy related pathways in F. oxysporum due to the oxidative stress generated by ROS. F. oxysporum infected zebrafish has recovered after lawsone therapy as a topical treatment suggesting that lawsone is a potential natural antifusariosis agent.

Inhibitory effects of an aqueous extract from Cortex Phellodendri on the growth and replication of broad-spectrum of viruses in vitro and in vivo.

BACKGROUND: Cortex Phellodendri (C. Phellodendri), the dried trunk bark of Phellodendron amurense Ruprecht, has been known as a traditional herbal medicine, showing several bioactivities. However, antiviral activity of C. Phellodendri aqueous extract (CP) not reported in detail, particularly aiming the prophylactic effectiveness. METHODS: In vitro CP antiviral activity evaluated against Influenza A virus (PR8), Vesicular Stomatitis Virus (VSV), Newcastle Disease Virus (NDV), Herpes Simplex Virus (HSV), Coxsackie Virus (H3-GFP) and Enterovirus-71 (EV-71) infection on immune (RAW264.7) and epithelial (HEK293T/HeLa) cells. Such antiviral effects were explained by the induction of antiviral state which was determined by phosphorylation of signal molecules, secretion of IFNs and cytokines, and cellular antiviral mRNA expression. Furthermore, Compounds present in the aqueous fractions confirmed by HPLC analysis and evaluated their anti-viral activities. Additionally, in vivo protective effect of CP against divergent influenza A subtypes was determined in a BALB/c mouse infection model. RESULTS: An effective dose of CP significantly reduced the virus replication both in immune and epithelial cells. Mechanically, CP induced mRNA expression of anti-viral genes and cytokine secretion in both RAW264.7 and HEK293T cells. Furthermore, the main compound identified was berberine, and shows promising antiviral properties similar to CP. Finally, BALB/c mice treated with CP displayed higher protection levels against lethal doses of highly pathogenic influenza A subtypes (H1N1, H5N2, H7N3 and H9N2). CONCLUSION: CP including berberine play an immunomodulatory role with broad spectrum antiviral activity, due to induction of antiviral state via type I IFN stimulation mechanism. Consequently, C. Phellodendri could be a potential source for promising natural antivirals or to design other antiviral agents for animal and humans.

Characterization and expression analysis of EF hand domain-containing calcium-regulatory gene from disk abalone: calcium homeostasis and its role in immunity.

The complete amino acid sequence of a calcium-regulatory gene (denoted as Ab-CaReg I) was identified from the disk abalone Haliotis discus discus cDNA library. The Ab-CaReg I is composed of 176 amino acids and the calculated molecular mass and isoelectric point were 20 and 4.2, respectively. The sequence homology of Ab-CaReg I was 28-30 and 18-27% of known calmodulin and troponin C, respectively. Four characteristic calcium-binding EF hand motifs with some modifications at conserved positions of known homologous calmodulin genes were observed in the sequence. The tissue-specific transcription analysis and variation of mRNA transcription level of Ab-CaReg I in gills and mantle after animals were immersed in seawater containing 2000 ppm CaCl(2) was quantified by SYBR Green real-time PCR analysis. Transcription variation of Ab-CaReg I in hemocytes and gills followed by bacteria challenge (Vibrio alginolyticus, Vibrio parahaemolyticus and Listeria monocytogenes) was used to investigate Ab-CaReg I in immune responses. Transcripts of Ab-CaReg I mRNA were mainly detected in hemocytes, mantle, muscle, gills, digestive tract and hepatopancreas with highest expression in hemocytes. The CaCl(2) immersion significantly altered the Ab-CaReg I mRNA transcription level by 3 h, compared to animals in normal seawater (control). The mRNA expression of Ab-CaReg I in gills and hemocytes was upregulated significantly to 11-fold and 4-fold in 3 h compared to control (uninfected), respectively, in bacteria-challenged abalones. The results suggest that Ab-CaReg I could be effectively induced to maintain internal Ca(2+) homeostasis of the animal due to influx of Ca(2+) in the cells by external stimuli such as a high dose of Ca(2+) and pathogens like bacteria.