Ainsua-Enrich, E. | Search bioRxiv

bioRxiv2025

ANDROGENS PROTECT ILC2S FROM FUNCTIONAL SUPPRESSION DURING INFLUENZA VIRUS INFECTION

Biological sex differences in morbidity upon influenza A virus (IAV) infection are linked to stronger IFN-centered immune responses in females, yet the regulatory role of sex hormone receptors in immune cell subsets is incompletely understood. Lung-resident group 2 innate lymphoid cells (ILC2s) express notably high levels of androgen receptors (AR). In IAV infection, ILC2s produce type 2 cytokines and facilitate tissue repair, but they also may be functionally suppressed by type 1 cytokines. Here we report sex differences in the magnitude of lung ILC2 functional suppression at the peak of sublethal IAV infection. Relative to males, ILC2s in females show attenuated proliferation, decreased propensity for IL-5 and amphiregulin production and reduced expression of GATA3 and IL-33R, features supported by divergent transcriptomes. Equivalent inflammatory cytokine levels and viral load suggested sex differences in ILC2-intrinsic factors. Indeed, naive female ILC2s showed elevated IFNGR expression and higher phospho-STAT1 levels following IFN{gamma} stimulation, and lymphocyte-restricted STAT1 deficiency reversed IAV-induced suppression of female ILC2s. Lymphocyte-restricted AR deficiency or loss of androgens via orchiectomy led to increased IFNGR expression and suppression of male ILC2s. These data support the hypothesis that intrinsic AR activity regulates IFNGR-STAT1 signaling pathways to preserve canonical ILC2 function in males during IAV infection.

immunology↗

bioRxiv2023

Novel Spike-stabilized trimers with improved production protect K18-hACE2 mice and golden Syrian hamsters from the highly pathogenic SARS-CoV-2 Beta variant.

Most COVID-19 vaccines are based on the SARS-CoV-2 Spike glycoprotein (S) or their subunits. However, the S shows some structural instability that limits its immunogenicity and production, hampering the development of recombinant S-based vaccines. The introduction of the K986P and V987P (S-2P) mutations increases the production of the recombinant S trimer and, more importantly, its immunogenicity, suggesting that these two parameters are related. However, S-2P still shows some molecular instability and it is produced with low yield. Thus, S-2P production can be further optimized. Here we described a novel set of mutations identified by molecular modelling and located in the S2 region of the Spike that increase S-2P production up to five-fold. Besides their immunogenicity, the efficacy of two representative S-2P-based mutants, S-29 and S-21, protecting from a heterologous SARS-CoV-2 Beta variant challenge was assayed in K18-hACE2 mice (an animal model of severe SARS-CoV-2 disease) and golden Syrian hamsters (GSH) (a moderate disease model). S-21 induced higher level of WH1 and Delta variants neutralizing antibodies than S-2P in K18-hACE2 mice three days after challenge. Viral load in nasal turbinate and oropharyngeal samples were reduced in S-21 and S-29 vaccinated mice. Despite that, only the S-29 protein protected 100% of K18-hACE2 mice from severe disease. When GSH were analyzed, all immunized animals were protected from disease development irrespectively of the immunogen they received. Therefore, the higher yield of S-29, as well as its improved immunogenicity and efficacy protecting from the highly pathogenic SARS-CoV-2 Beta variant, pinpoint the S-29 spike mutant as an alternative to the S-2P protein for future SARS-CoV-2 vaccine development. Authors summaryThe rapid development of SARS-CoV-2 vaccines have been pivotal in the control of the COVID-19 pandemic worldwide. Most of these vaccines include the S glycoprotein as the main immunogen since this protein, and particularly its receptor binding domain (RBD), is the major target of neutralizing antibodies. SARS-CoV-2 have been evolving from the beginning of the pandemic and several variants with increased transmissibility, pathogenicity or resistance to infection- or vaccine-induced immunity have emerged. Different strategies have been adopted to improve vaccine protection including additional booster doses or the adaptation of the S immunogens to the novel SARS-CoV-2 variants. As a complementary strategy we have identified a combination of non-proline mutations that increase S production by 5-fold (S-29 protein). Despite the sequence of this novel S-29 immunogen is based on the ancestral SARS-CoV-2 WH1 variant, it effectively protects animal model from the highly pathogenic and neutralization resistant SARS-CoV-2 Beta variant. Thus, we describe a novel set of mutations that can increase the production and efficacy of S-based COVID-19 vaccines.

immunology↗

bioRxiv2020

Stable neutralizing antibody levels six months after mild and severe COVID-19 episode

Understanding mid-term kinetics of immunity to SARS-CoV-2 is the cornerstone for public health control of the pandemic and vaccine development. However, current evidence is rather based on limited measurements, thus losing sight of the temporal pattern of these changes1-6. In this longitudinal analysis, conducted on a prospective cohort of COVID-19 patients followed up to 242 days, we found that individuals with mild or asymptomatic infection experienced an insignificant decay in neutralizing activity that persisted six months after symptom onset or diagnosis. Hospitalized individuals showed higher neutralizing titers, which decreased following a two-phase pattern, with an initial rapid decline that significantly slowed after day 80. Despite this initial decay, neutralizing activity at six months remained higher among hospitalized individuals. The slow decline in neutralizing activity at mid-term contrasted with the steep slope of antibody titers change, reinforcing the hypothesis that the quality of immune response evolves over the post-convalescent stage4,5.

immunology↗