Nano-chitosan hydrogel alleviates Candida albicans-induced health alterations in Nile tilapia (Oreochromis niloticus): antioxidant response, neuro-behaviors, hepato-renal functions, and histopathological investigation

Abstract

Background: Candida albicans infection induces economic losses in aquaculture practices. Currently, the success of the nanotechnology field has gained more consideration in the aquaculture sector as it bestows favorable impacts in remedies in comparison to traditional practices.

Objective: The present study was conducted to assess the role of nano chitosan gel (NCG) exposure via water in managing the deteriorating impacts triggered by C. albicans in Nile tilapia, Oreochromis niloticus. Hepato-renal function, behavioral and stress response, neurological function, hepatic antioxidant/oxidant status, and histopathological architectures were investigated.

Methods: A total of 160 fish (average weight: 50.00 ± 6.30 g) were randomly assigned to four groups, each with four replicates: control, NCG, C. albicans, and NCG + C. albicans. The NCG was applied as bath treatment at a concentration of 75 µg/L for ten days.

Results: The outcomes demonstrated that the C. albicans challenged fish exhibited obvious behavioral alterations including loss of equilibrium, surfacing, abnormal swimming and movement, and aggression. Infection with C. albicans caused an elevation in hepato-renal biomarkers (alanine and aspartate aminotransferases, alkaline phosphatase, urea, and creatinine), stress-related indices (glucose, cortisol, nor-epinephrine, and 8-hydroxy-2-deoxyguanosine), and lipid peroxides (malondialdehyde). Moreover, it caused a noticeable decline in the hepatic antioxidant indices (total antioxidant capacity and reduced glutathione content) and acetylcholinesterase activity. The hepatic, renal, and brain architectures were severely damaged by the C. albicans challenge, exhibiting significant fatty changes, necrosis, vacuolation, and congestion. Remarkably, the aqueous application of NCG in the C. albicans-challenged fish ameliorated all the aforementioned biomarkers and facilitated the regeneration of histopathological changes.

Conclusion: Overall, the application of NCG in the aquatic environment is an effective tool for managing C. albicans infection in Nile tilapia. Moreover, it can be utilized in combating stress conditions in the aquaculture sector.

Keywords: Candida albicans; Antioxidant status; Biological stress; Histopathology; Nano chitosan gel; Nile tilapia.

Fig. 1

Characterization images of nano chitosan gel. A TEM (100 nm). B 3D AFM. C XRD. D Zeta potential. E DLS

Fig. 2

Impact of nano chitosan gel (NCG) bath on hepatic antioxidant/oxidant variable of Nile tilapia experimentally infected with C. albicans for ten days. A Total antioxidant capacity (TAC; P < 0.001). B Reduced glutathione content (GSH; P < 0.001). C Malondialdehyde (MDA; P < 0.001). Bars (means ± SE) that do not share similar superscripts differ substantially (One way ANOVA; P < 0.05)

Fig. 3

Photomicrographs of hepato-pancreas sections (H&E). A & B Hepato-pancreases of the control and nano chitosan gel (NCG) groups reveal normal histological configurations of hepatic cords (stars) and pancreatic acini (arrowheads). C The hepato-pancreas of the C. albicans group reveals markedly distributed fatty changes (red arrow) and necrotic pancreatic acini with pyknotic nuclei (black arrow). D Hepato-pancreas of the NCG + C. albicans group reveals less number of fatty degenerated cells (arrow) and amelioration in pancreatic acinar epithelium (arrowhead). Scale bar 20 μm

Fig. 4

Photomicrographs of kidney sections (H&E). A & B Kidneys of the control and nano chitosan gel (NCG) groups reveal normal histological configurations of renal tubular epithelium (arrows) and glomerular tufts (arrowheads). C Kidney of the C. albicans group reveals necrosis of some renal epithelium with the presence of remnant cytoplasmic and nuclear material (black arrowhead), congested renal blood vessels (red arrow), and hypo-cellular glomeruli (red arrowhead). D Kidney of the NCG + C. albicans group reveals maintenance of renal tissue with few degenerative changes in some renal tubules (arrow). Scale bar 20 μm

Fig. 5

Photomicrographs of brain sections (H&E). A & B Brains of the control and nano chitosan gel (NCG) groups reveal normal histological architectures of neurons (arrows), glia cells, and neuropil (stars). C Brain of the C. albicans group reveals a marked area of vacuolated neuropil (arrowhead) and a large number of pyknotic neurons with perineuronal space (arrow). D Brain of the NCG + C. albicans group reveals an improvement in the most neuronal cell body (arrow), neuropil (star) with the presence of few areas of vacuolated neuropil (arrowhead). Scale bar 20 μm