Fungal α-1,3-Glucan as a New Pathogen-Associated Molecular Pattern in the Insect Model Host Galleria mellonella

Abstract

Recognition of pathogen-associated molecular patterns (PAMPs) by appropriate pattern recognition receptors (PRRs) is a key step in activating the host immune response. The role of a fungal PAMP is attributed to β-1,3-glucan. The role of α-1,3-glucan, another fungal cell wall polysaccharide, in modulating the host immune response is not clear. This work investigates the potential of α-1,3-glucan as a fungal PAMP by analyzing the humoral immune response of the greater wax moth Galleria mellonella to Aspergillus niger α-1,3-glucan. We demonstrated that 57-kDa and 61-kDa hemolymph proteins, identified as β-1,3-glucan recognition proteins, bound to A. niger α-1,3-glucan. Other hemolymph proteins, i.e., apolipophorin I, apolipophorin II, prophenoloxidase, phenoloxidase activating factor, arylphorin, and serine protease, were also identified among α-1,3-glucan-interacting proteins. In response to α-1,3-glucan, a 4.5-fold and 3-fold increase in the gene expression of antifungal peptides galiomicin and gallerimycin was demonstrated, respectively. The significant increase in the level of five defense peptides, including galiomicin, corresponded well with the highest antifungal activity in hemolymph. Our results indicate that A. niger α-1,3-glucan is recognized by the insect immune system, and immune response is triggered by this cell wall component. Thus, the role of a fungal PAMP for α-1,3-glucan can be postulated.

Combination of 3-O-Levulinoyl and 6-O-Trifluorobenzoyl Groups Ensures α-Selectivity in Glucosylations: Synthesis of the Oligosaccharides Related to Aspergillus fumigatus α-(1 → 3)-d-Glucan

“…When compared to perbenzylated donor 4, donor 8 with a levulinoyl group at O-3 showed an improvement in α-selectivity ratio from 1.7:1 (entry 6) to 2.2:1 (entry 10). Benzoyl (5) and TFB ( 6) at O-6, both enhanced α-stereoselectivity (as for entries (α:β): 1 (2.3:1), 2 (2.4:1), 7 (3.1:1), 8 (3.5:1), 13 (9.0:1), 14 (10.2:1), 18 (4.9:1), 19 (5.2:1)) more effectively than levulinoyl at O-3 (8). Compared to perbenzylated donor 4 (entry 6), donors 5 with benzoyl (Bz), 7 with PFB and 6 with TFB groups at O-6 (entries 7−9) demonstrated approximately a twofold increase in α-selectivity.…”

“…However, the design of α-glucosylation methods as a special example of 1,2- cis -glycosylations is a distinct outstanding issue − and a fascinating task in oligosaccharide synthesis. The α-glucoside bond is present in various α-(1 → 2)-, , α-(1 → 3)-, , α-(1 → 4)-, , and α-(1 → 6)-glucans produced by fungi and bacteria. Of particular interest are α-(1 → 3)-glucans, which are widely represented in fungus Aspergillus fumigatus, responsible for a plethora of diseases in immunocompromised people, and whose role in interaction with host immunity has been actively studied. − …”

“…1 H-NMR (600 MHz, CDCl 3 ) δ 7.39−7.24 (m, 13H (+CHCl 3 ), Ar), 7.22−7.18 (m, 2H, Ar), 5.21 (t, J 3,4 = J 3,2 = 9.4 Hz, 1H, H-3), 4.86 (d, J A,B = 11.9 Hz, BnA), 4.66−4.61 (m, 2H, Bn), 2.59−2.55 (m, 2H, Bn), 4.53 (d, J 1,2 = 7.9 Hz, 1H, H-1), 4.49 (d, J B,A = 11.2 Hz, 1H, Bn′B), 4.04 (sept, J CH,CH3 = 6.2 Hz, 1H, CH(iPr)), 3.73 (dd, J 6A,6B = 10.7 Hz, J 6A,5 = 1 8. Hz, H-6A), 3.69 (dd, J 6B,6A = 10.7 Hz, J 6B,5 = 4.6 Hz, H-6B), 3.61 (t, J 4,3 = J 4,5 = 9.5 Hz, 1H, H-4), 3.50 (m, 1H, H-5), 3.34 (dd, J 2,1 = 7.7 Hz, J 2,3 = 9.6 Hz, H-2), 2.58 (m, 2H, CH 2 (Lev)), 2.38 (m, 2H, CH 2 (Lev)), 2.14 (s, 3H, CH 3 (Lev)), 1.33 (d, J CH3,CH = 6.3 Hz, CH 3 (iPr)), 1.25 (d, J CH3,CH = 6.2 Hz, CH 3 (iPr)).…”

“…α , H-6 β , H-4 α , H-4 β ), 3.62 (dd, J 6B,5 = 1.6 Hz, J 6B,6A = 10 8. Hz, H-6Bα), 3.54−3.47 (m, 3.1H, H-2 α , H-5 β ), 3.40 (dd, J 2,1 = 7.9 Hz, J 2,3 = 9.2 Hz, H-2 β ), 2.70−2.30 (m, 13.3H, Lev), 2.15, 2.13 (2 s, 9.6H, CH 3 (Lev)).…”

Humoral immune response of Galleria mellonella after mono‐ and co‐injection with Hypericum perforatum extract and Candida albicans

“…The humoral response is activated by the recognition of immunoregulator by the appropriate pattern recognition receptors (PRRs) that recognize unique structures or patterns on the immunoregulator (pathogen-associated molecular patterns, PAMPs), or recognize the damaged or wound region in the larval body (damage-associated molecular patterns, DAMPs) [4,26]. The bacterial (e.g., peptidoglycan, lipoteichoic acids, and lipopolysaccharides) and fungal (e.g., b-1, 3-glucan) cell wall components are examples of well-known PAMPs [27,28]. The sensing of immunoregulator and its properties (e.g., size and amount) induces activation of relevant signaling pathways (e.g., JAK-STAT pathway), which cause the synthesis of defense molecules (proteins, AMPs, and ROS/RNS), melanization, and hemolymph coagulation [4,29,30].…”