Cultivable fungal diversity in two karstic caves in Italy: under-investigated habitats as source of putative novel taxa

Microbial diversity of caves is largely understudied and its possible applications are still unknown. Autochthonous fungi, in particular, may have the potential to biomineralize metals and may be used as promising agents for bioremediation of polluted sites; thus, unearthing the fungal diversity in hypogean ecosystems is nowadays of utmost importance. To start addressing this knowledge gap, the cultivable mycobiota of two neighbouring caves-one natural and one exploited for touristic purposes-were characterised and compared by studying fungi isolated from sediments collected at increasing distances from the entrance. Overall, 250 fungal isolates ascribable to 69 taxa (mainly Ascomycota) were found, a high percentage of which was reported in caves for the first time. The sediments of the touristic cave displayed a richer and more diversified community in comparison with the natural one, possibly due to visitors carrying propagules or organic material. Considering that these environments are still poorly explored, chances to detect new fungal lineages are not negligible.

The Ablation of Sensory Neurons Expressing the Nav1.8 Sodium Channel Improves Glucose Homeostasis and Amplifies the GLP-1 Signaling in Obese Female Mice

SCOPE

Sensory neurons expressing the sodium channel Nav1.8 contain a repertoire of receptors for nutrient, hormonal, and inflammatory ligands. However, their function in key regulators of energy homeostasis control is not well understood and is completely unexplored in females.

METHODS AND RESULTS

Mice lacking neurons expressing the sodium channel Nav1.8 were generated using an ablation strategy based on cre recombinase-mediated expression of diphtheria toxin fragment A (DTA) (Nav1.8-cre/DTA mice) to investigate whether these neurons modulate body weight, food intake, gut hormone secretion, gastrointestinal transit, and glucose tolerance in response to nutrient challenges in a sex-dependent manner. Male Nav1.8-cre/DTA mice show resistance to gain weight in response to high-fat high-sugar diet (HFHSD), whereas females lacking Nav1.8+ neurons have improved oral glucose tolerance accompanied by higher insulin levels and attenuated glucagon secretion after an oral glucose load. Female Nav1.8-cre/DTA mice also show higher fasting and postprandial glucagon like peptide-1 (GLP-1) levels with an increased number of GLP-1-positive cells. Finally, ablation of Nav1.8-expressing neurons accelerates the gastrointestinal transit in female mice under HFHSD.

CONCLUSION

This data demonstrates sex-dependent differences in the Nav1.8-mediated regulation of energy metabolism, and provides new insights that may help in the design of sex-specific neuromodulation therapies for metabolic disorders induced by diets rich in fats and simple sugars.

Antibody-dependent NK-cell and neutralizing antibody responses against the Spike protein of Wuhan-Hu-1 and Omicron BA.1 SARS-CoV-2 variants in vaccinated experienced and vaccinated naïve individuals

Antibodies triggering Fc-mediated NK cell activity may contribute to protection against disease caused by SARS-CoV-2 infection in humans. However, how these Fc-mediated humoral responses compare between individuals displaying hybrid immunity (Vac-ex) and those fully vaccinated with no history of SARS-CoV-2 infection (Vac-n) and whether they correlate with neutralizing antibody (NtAb) responses remains largely undetermined. In this retrospective study serum samples from 50 individuals (median age, 44.5 years; range, 11-85; 25 males), 25 Vac-ex and 25 Vac-n were studied. A flow-cytometry-based antibody-mediated NK-cell activation assay was used to quantitate effector NK-cells stimulated to express LAMP1 (lysosomal associated membrane protein 1), MIP1 (Macrophage inflammatory protein 1), and interferon-γ (IFNγ); NK cells isolated from two donors (D1 and D2) were used. NtAb levels targeting the Spike protein of Wuhan-Hu-1 and Omicron BA.1 SARS-CoV-2 variants were quantitated using a SARS-CoV-2 S pseudotyped neutralization assay. Regardless of the SARS-CoV-2 variant S antigen used in the NK-cell activation assay, the frequency of NK cells stimulated to express LAMP-1, MIP1β, and IFNγ was higher in Vac-ex compared with Vac-n (p values ranging from 0.07 to 0.006) for D1; this was only seen for BA.1 when NK cells from D2 were employed. The frequency of functional NK cells activated by antibody binding to either Wuhan-Hu-1 or Omicron BA.1 S protein was not significantly different for both VAC-ex and VAC-n. In contrast, NtAb titers against BA.1 were around 10-fold lower than that against Wuhan-Hu-1. Vac-ex displayed higher NtAb titers against both (sub)variants than Vac-n. NK-cell responses correlated poorly with NtAb titers (ρ ≤ 0.30). The data demonstrate higher cross-reactivity across variants of concern for antibodies triggering Fc-mediated NK cell than for NtAb. Moreover, Vac-Ex seemed to display more robust functional antibody responses as compared with Vac-n.