Heat shock proteins (HSP 90, 70, 60, and 27) in Galleria mellonella (Lepidoptera) hemolymph are affected by infection with Conidiobolus coronatus (Entomophthorales)

Abstract

Invertebrates are becoming more popular models for research on the immune system. The innate immunity possessed by insects shows both structural and functional similarity to the resistance displayed by mammals, and many processes occurring in insect hemocytes are similar to those that occur in mammals. The humoral immune response in insects acts by melanization, clotting and the production of reactive oxygen species and antimicrobial peptides, while the cellular immunity system is based on nodulation, encapsulation and phagocytosis. An increasingly popular insect model in biological research is Galleria mellonella, whose larvae are sensitive to infection by the entomopathogenic fungus Conidiobolus coronatus, which can also be dangerous to humans. One group of factors that modulate the response of the immune system during infection in mammals are heat shock proteins (HSPs). The aim of this study was to investigate whether infection by C. coronatus in G. mellonella hemolymph is accompanied by an increase of HSP90, HSP70, HSP60 and HSP27. Larvae (five-day-old last instar) were exposed for 24 hours to fully-grown and sporulating fungus. Hemolymph was collected either immediately after termination of exposure (F24) or 24 hours later (F48). The concentration of the HSPs in hemolymph was determined using ELISA. Immunolocalization in hemocytes was performed using fluorescence microscopy and flow cytometry. HSP90, HSP70, HSP60 and HSP27 were found to be present in the G. mellonella hemocytes. HSP60 and HSP90 predominated in healthy insects, with HSP70 and HSP27 being found in trace amounts; HSP60 and HSP27 were elevated in F24 and F48, and HSP90 was elevated in F48. The fungal infection had no effect on HSP70 levels. These findings shed light on the mechanisms underlying the interaction between the innate insect immune response and entomopathogen infection. The results of this innovative study may have a considerable impact on research concerning innate immunology and insect physiology.

Interplay between Fungal Infection and Bacterial Associates in the Wax Moth Galleria mellonella under Different Temperature Conditions

“…We also observed a downregulation in HSP70 expression in the fat body in response to C. militaris infection. Previous studies reported either an increase in HSP expression in different tissues of G. mellonella after infection with B. bassiana and Conidiobolus coronatus , or no change compared to uninfected insects [ 7 , 61 , 81 ]. These inconstancies may be caused by differences in pathogenesis that occur after infection with different fungal species and strains.…”

Antimicrobial Peptides: Classification, Design, Application and Research Progress in Multiple Fields

“…Chaperones are key proteins for correctly folding and assembling newly synthesized proteins and make them have stereoisomerism, which makes AMPs have cell selectivity and can prevent cytotoxicity. According to a previous review: both pyrhocoricin and drosocin can prevent DnaK from refolding misfolded proteins by inducing a permanent closure of the DnaK peptide-binding cavity (Kragol et al, 2001;Le et al, 2017;Wrońska and Boguś, 2020).…”

Cell Line Platforms Support Research into Arthropod Immunity

“…These two HSPs are primarily regulated by PGA 1 , not heat shock. Treating the cells with an inhibitor of cyclooxygenase, aspirin, did not influence the HSP70 levels when the cells were maintained at their standard growth temperature (28 • C) but upregulated their synthesis at a higher temperature of 37 • C. HSPs act in a variety of immunoregulatory roles at the intracellular and extracellular levels [99,100].…”

“…AMPs typically appear in hemolymph of infected insects about 6-12 h after infections. Other chemicals include lysozymes, oxygen and nitrogen-free radicals, stress-related proteins, and enzyme cascades, including the PPO pathway [33,41,99,100]. Humoral responses have been activated against bacterial, fungal, and viral infections.…”