The complex bidirectional communication system existing between the gastrointestinal tract and the brain initially termed the “gut–brain axis” and renamed the “microbiota–gut–brain axis”, considering the pivotal role of gut microbiota in sustaining local and systemic homeostasis, has a fundamental role in the pathogenesis of Inflammatory Bowel Disease (IBD). The integration of signals deriving from the host neuronal, immune, and endocrine systems with signals deriving from the microbiota may influence the development of the local inflammatory injury and impacts also more distal brain regions, underlying the psychophysiological vulnerability of IBD patients. Mood disorders and increased response to stress are frequently associated with IBD and may affect the disease recurrence and severity, thus requiring an appropriate therapeutic approach in addition to conventional anti-inflammatory treatments. This review highlights the more recent evidence suggesting that alterations of the microbiota–gut–brain bidirectional communication axis may concur to IBD pathogenesis and sustain the development of both local and CNS symptoms. The participation of the main microbial-derived metabolites, also defined as “postbiotics”, such as bile acids, short-chain fatty acids, and tryptophan metabolites in the development of IBD-associated gut and brain dysfunction will be discussed. The last section covers a critical evaluation of the main clinical evidence pointing to the microbiome-based therapeutic approaches for the treatment of IBD-related gastrointestinal and neuropsychiatric symptoms.

Heat shock proteins (HSPs) play a key role in enhancing insect resilience to abiotic and biotic stresses by preserving cellular integrity and modulating immune responses. This review summarizes the main functions of HSPs in insects, including protein stabilization, interaction with antioxidant systems, and involvement in the innate immune response. The expression of HSPs under environmental conditions reflects their evolutionary adaptation to various stressors, including thermal changes, chemical exposure, and pathogens. Future research should focus on the interaction between HSPs and other stress response systems to improve our understanding of insect adaptation. Furthermore, in the context of global climate change, HSPs emerge as a crucial resilience factor and potential biomarkers for environmental monitoring.

The aim of this work was to develop an experimental protocol for the infection of Galleria mellonella with Gram-positive bacteria. Some physiological characteristics of these insects are comparable to those of vertebrates, therefore allowing the replacement of mammals in the preclinical phases of drug development. G. mellonella Linnaeus 1758 (Lepidoptera: Pyralidae) is accepted as an alternative model for the study of infectious diseases. Since data on infection procedures with different bacterial strains are scarce and sometimes conflicting, also due to different and non-uniform protocols, we developed an experimental protocol that would allow for controlled and repeatable infections, using the Gram-positive bacterium GRAS (Generally Regarded As Safe) Micrococcus luteus. After analyzing the morphology and defining the growth rate of M. luteus, doses of between 10¹ and 10⁶ CFU/larvae were administered to late-stage larvae. The survival rate of the larvae was monitored up to 7 days and the LD₅₀ determined. The bacterial clearance capacity of the larvae after injection with 10³ and 10⁵ CFU/larvae was assessed by hemolymph bacterial load analysis. The results made it possible to define the growth curve of M. luteus correlated with the CFU count; based on the LD₅₀ (10^3.8 CFU/larvae) calculated on the survival of G. mellonella, infections were carried out to evaluate the immune efficiency of the larvae in bacterial clearance. This protocol, standardized on G. mellonella larvae, could provide a functional tool to study the course of bacterial infections.

Perturbations of the gastrointestinal (GI) microbiota (i.e. dysbiosis) in early life may induce vulnerability of the enteric nervous system (ENS), contributing to early onset GI disorders, such as irritable bowel syndrome (IBS). Probiotics, such as Lacticaseibacillus rhamnosus GG (LGG), may improve pediatric digestive disorders; however, the mechanisms involved, including effects on the ENS, are not yet fully understood. In this study, the long-lasting consequences of antibiotic-induced dysbiosis on intestinal neuromuscular function, as well as the effect of LGG, were evaluated in juvenile female and male mice. One week after antibiotic treatment cessation, broad-spectrum antibiotic treatment induced significant taxonomic changes in both sexes compared to untreated control animals. These changes appeared earlier and involved more potentially harmful bacterial taxa in females than in males. LGG effectively prevented alterations in microbial communities in both sexes, with a more pronounced protective effect in males. Dysbiosis reduced transit efficiency, nitrergic relaxations, and tachykinergic contractions only in females, with no significant effect of LGG in this group. In both sexes, dysbiosis decreased cholinergic contractions; however, LGG restored the excitatory responses to control levels only in males. In summary, early antibiotic-induced dysbiosis in juvenile mice leads to persistent effects during late adolescence on both gut microbiota composition and neuromuscular function. These alterations are more pronounced and less responsive to LGG treatment in females. The findings underscore the critical role of the enteric microbiota in early-life development of functional gastrointestinal disorders with sex-specific features, such IBS.

Heat shock proteins (HSPs), particularly HSP90, play a vital role in insect responses to environmental and biotic stresses by maintaining protein stability and supporting immune defenses. This study explores HSP90 regulation in Galleria mellonella larvae following exposure to the nematode Steinernema carpocapsae and its symbiotic bacterium Xenorhabdus nematophila. Exposure to live nematodes caused slight changes in HSP90 expression, while non-viable nematodes had no effect, suggesting that nematode secretions or symbiotic bacteria do not directly influence HSP90 levels. However, nematodes with altered surface properties significantly increased HSP90 expression. X. nematophila also moderately elevated HSP90 levels but this effect disappeared when weakly bound surface proteins were removed. Interestingly, under thermal stress, live nematodes reduced heat-induced HSP90 expression, whereas surface-treated nematodes enhanced it. These findings suggest that HSP90 modulation is influenced by biological control agents, highlighting a potential link between HSP90 and immune detection of invaders. This interaction may be crucial in adapting biological control strategies in response to climate change. Further research is needed to clarify HSP activation pathways, host immune interactions, and mechanisms of entomopathogen immune evasion, particularly under varying environmental temperatures, to enhance bioinsecticide efficacy.

The increase in the world population and consequent rise in food demand have led to the extensive use of chemical pesticides, causing environmental and health concerns. In response, biological control methods, particularly those involving microbial agents, have emerged as sustainable alternatives within integrated pest management. This study highlights the potential of Lysinibacillus fusiformis as a biocontrol agent against the dipteran Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), a pest responsible for damaging soft-skinned fruits. Experimental treatments using vegetative cells, spores, and secondary metabolites of L. fusiformis on D. suzukii larvae demonstrated significant larvicidal effects, accompanied by observable changes in gut morphology under microscopy. Moreover, preliminary immunological assays showed the interference of this bacterium with the host immune system. All the results indicate the suitability of L. fusiformis for its possible integration into sustainable agricultural practices, although additional research is required to understand its applicability in the field.