Saliva and Plasma Neutralizing Activity Induced by the Administration of a Third bnt162b2 Vaccine Dose

The BNT162b2 vaccine induces neutralizing activity (NA) in serum, but no data are available on whether a third-dose activates specific-immunity within the oral mucosa, representing the primary route of viral-entry. To carefully address this issue, we investigated if such immunity is boosted by SARS-CoV-2-infection; how long it is maintained over-time; and if it protects against the SARS-CoV-2 lineage B.1 (EU) and the emerging Delta and Omicron variants. NA was measured in plasma and saliva samples from: uninfected SARS-CoV-2-Vaccinated (SV), subjects infected prior to vaccination (SIV), and subjects who were infected after the second (SIV2) or the third (SIV3) vaccine dose. Samples were collected immediately before (T0), 15 days (T1), and 90 days (T2) post third-dose administration (SV and SIV), or 15 days post-infection (SIV2 and SIV3). In all the enrolled groups, NA in plasma and saliva: (i) was higher against EU compared to the other variants at all time-points (SV: T0 and T1, EU vs. both Delta and Omicron p < 0.001; T2 p < 0.01) (SIV: T0, EU vs. Delta p < 0.05; EU vs. Omi p < 0.01; T1 and T2 EU vs. Delta p < 0.01; EU vs. Omi p < 0.001); (ii) was boosted by the administration of the third dose; iii) declined over-time, albeit being detectable in almost all subjects at T2. The monitoring of NA over time will be important in clarifying if different NA levels may influence either acquisition or course of infection to properly plan the timing of a fourth vaccine dose administration

Anti-Inflammatory Effects of Immunostimulation in Patients with COVID-19 Pneumonia

Background: The effects of immunomodulators in patients with Coronavirus Disease 2019 (COVID-19) pneumonia are still unknown. We investigated the cellular inflammatory and molecular changes in response to standard-of-care + pidotimod (PDT) and explored the possible association with blood biomarkers of disease severity. Methods: Clinical characteristics and outcomes, neutrophil-to-lymphocyte ratio (NLR), plasma and cell supernatant chemokines, and gene expression patterns after SARS-CoV-2 and influenza (FLU) virus in vitro stimulation were assessed in 16 patients with mild-moderate COVID-19 pneumonia, treated with standard of care and PDT 800 mg twice daily (PDT group), and measured at admission, 7 (T1), and 12 (T2) days after therapy initiation. Clinical outcomes and NLR were compared with age-matched historical controls not exposed to PDT. Results: Hospital stay, in-hospital mortality, and intubation rate did not differ between groups. At T1, NLR was 2.9 (1.7–4.6) in the PDT group and 5.5 (3.4–7.1) in controls (p = 0.037). In the PDT group, eotaxin and IL-4 plasma concentrations progressively increased (p p < 0.05), while at genetic transcription level, Pathogen Recognition Receptors (TRLs) were upregulated, especially in FLU-stimulated conditions. Conclusions: Immunomodulation exerted by PDT and systemic corticosteroids may foster a restoration in the innate response to the viral infection. These results should be confirmed in larger RCTs

Natural SARS-CoV-2 Infection Affects Neutralizing Activity in Saliva of Vaccinees

BACKGROUND: SARS-CoV-2 transmission mainly occurs through exposure of the upper airway mucosa to infected secretions such as saliva, which are excreted by an infected person. Thus, oral mucosal immunity plays a central role in the prevention of and early defense against SARS-CoV-2 infection. Although virus-specific antibody response has been extensively investigated in blood samples of SARS-CoV-2-infected patients and vaccinees, local humoral immunity in the oral cavity and its relationship to systemic antibody levels needs to be further addressed. MATERIAL AND METHODS: We fine-tuned a virus neutralization assay (vNTA) to measure the neutralizing activity (NA) of plasma and saliva samples from 20 SARS-CoV-2-infected (SI), 40 SARS-CoV-2-vaccinated (SV), and 28 SARS-CoV-2-vaccinated subjects with a history of infection (SIV) using the “wild type” SARS-CoV-2 lineage B.1 (EU) and the Delta (B.1.617.2) strains. To validate the vNTA results, the presence of neutralizing antibodies (NAbs) to the spike receptor binding domain (RBD) was evaluated with an ELISA assay. RESULTS: NA to SARS-CoV-2 lineage B.1 (EU) was present in plasma samples from all the tested subjects, with higher titers in SIV compared to both SI and SV. Conversely, NA was detected in saliva samples from 10.3% SV, 45% SI, and 92.6% SIV, with significantly lower titers in SV compared to both SI and SIV. The detection of NAbs in saliva reflected its reduced NA in SV. DISCUSSION: The difference in NA of plasma vs. saliva was confirmed in a vNTA where the SARS-CoV-2 B.1 and Delta strains were tested head-to-head, which also revealed a reduced NA of both specimens compared to the B.1 variant. CONCLUSIONS: The administration of SARS-CoV-2 vaccines was associated with limited virus NA in the oral cavity, as measured in saliva and in comparison to plasma. This difference was more evident in vaccinees without a history of SARS-CoV-2 infection, possibly highlighting the importance of local exposure at the site of virus acquisition to effectively prevent the infection and block its spread. Nevertheless, the presence of immune escape mutations as possibly represented by the SARS-CoV-2 Delta variant negatively affects both local and systemic efficacy of NA associated with vaccination

Dopamine Reduces SARS-CoV-2 Replication In Vitro through Downregulation of D2 Receptors and Upregulation of Type-I Interferons

Recent evidence suggests that SARS-CoV-2 hinders immune responses via dopamine (DA)-related mechanisms. Nonetheless, studies addressing the specific role of DA in the frame of SARS-CoV-2 infection are still missing. In the present study, we investigate the role of DA in SARS-CoV-2 replication along with potential links with innate immune pathways in CaLu-3 human epithelial lung cells. We document here for the first time that, besides DA synthetic pathways, SARS-CoV-2 alters the expression of D1 and D2 DA receptors (D1DR, D2DR), while DA administration reduces viral replication. Such an effect occurs at non-toxic, micromolar-range DA doses, which are known to induce receptor desensitization and downregulation. Indeed, the antiviral effects of DA were associated with a robust downregulation of D2DRs both at mRNA and protein levels, while the amount of D1DRs was not significantly affected. While halting SARS-CoV-2 replication, DA, similar to the D2DR agonist quinpirole, upregulates the expression of ISGs and Type-I IFNs, which goes along with the downregulation of various pro-inflammatory mediators. In turn, administration of Type-I IFNs, while dramatically reducing SARS-CoV-2 replication, converges in downregulating D2DRs expression. Besides configuring the CaLu-3 cell line as a suitable model to study SARS-CoV-2-induced alterations at the level of the DA system in the periphery, our findings disclose a previously unappreciated correlation between DA pathways and Type-I IFN response, which may be disrupted by SARS-CoV-2 for host cell invasion and replication

Precursor forms of vitamin D reduce HIV-1 infection in vitro

Artículo CientíficoBackground: Although the anti-HIV-1 effects of vitamin D (VitD) have been reported, mechanisms behind such protection remain largely unexplored. Methods: The effects of two precursor forms (cholecalciferol/calciol at 0.01, 1 and 100 nM and calcidiol at 100 and 250 nM) on HIV-1 infection, immune activation, and gene expression were analyzed in vitro in cells of Colombian and Italian healthy donors. We quantified levels of released p24 by enzyme-linked immunosorbent assay, of intracellular p24 and cell-surface expression of CD38 and HLA-DR by flow cytometry, and mRNA expression of antiviral and immunoregulatory genes by real-time reverse transcriptionpolymerase chain reaction. Results: Cholecalciferol decreased the frequency of HIV-1-infected p24+CD4+ T cells and levels of p24 in supernatants in a dosedependent manner. Moreover, the CD4+CD38+HLA-DR+ and CD4+CD382HLA-DR+ subpopulations were more susceptible to infection but displayed the greatest cholecalciferol-induced decreases in infection rate by an X4-tropic strain. Likewise, cholecalciferol at its highest concentration decreased the frequency of CD382HLA-DR+ but not of CD38+HLA-DR+ T-cell subsets. Analyzing the effects of calcidiol, the main VitD source for immune cells and an R5-tropic strain as the most frequently transmitted virus, a reduction in HIV-1 productive infection was also observed. In addition, an increase in mRNA expression of APOBEC3G and PI3 and a reduction of TRIM22 and CCR5 expression, this latter positively correlated with p24 levels, was noted. Conclusions: VitD reduces HIV-1 infection in T cells possibly by inducing antiviral gene expression, reducing the viral co-receptor CCR5 and, at least at the highest holecalciferol concentration, by promoting an HIV-1-restrictive CD38+HLA-DR2 [email protected]

Salivary miRNA Profiles in COVID-19 Patients with Different Disease Severities

: The oral mucosa is the first site of SARS-CoV-2 entry and replication, and it plays a central role in the early defense against infection. Thus, the SARS-CoV-2 viral load, miRNAs, cytokines, and neutralizing activity (NA) were assessed in saliva and plasma from mild (MD) and severe (SD) COVID-19 patients. Here we showed that of the 84 miRNAs analyzed, 8 were differently expressed in the plasma and saliva of SD patients. In particular: (1) miRNAs let-7a-5p, let-7b-5p, and let-7c-5p were significantly downregulated; and (2) miR-23a and b and miR-29c, as well as three immunomodulatory miRNAs (miR-34a-5p, miR-181d-5p, and miR-146) were significantly upregulated. The production of pro-inflammatory cytokines (IL-1β, IL-2, IL-6, IL-8, IL-9, and TNFα) and chemokines (CCL2 and RANTES) increased in both the saliva and plasma of SD and MD patients. Notably, disease severity correlated with NA and immune activation. Monitoring these parameters could help predict disease outcomes and identify new markers of disease progression

<i>Leishmania tarentolae</i> as an Antigen Delivery Platform: Dendritic Cell Maturation after Infection with a Clone Engineered to Express the SARS-CoV-2 Spike Protein

Background: Protozoa of the genus Leishmania are characterized by their capacity to target macrophages and Dendritic Cells (DCs). These microorganisms could thus be exploited for the delivery of antigens to immune cells. Leishmania tarentolae is regarded as a non-pathogenic species; it was previously used as a biofactory for protein production and has been considered as a candidate vaccine or as an antigen delivery platform. However, results on the type of immune polarization determined by L. tarentolae are still inconclusive. Methods: DCs were derived from human monocytes and exposed to live L. tarentolae, using both the non-engineered P10 strain, and the same strain engineered for expression of the spike protein from SARS-CoV-2. We then determined: (i) parasite internalization in the DCs; and (ii) the capacity of the assayed strains to activate DCs and the type of immune polarization. Results: Protozoan parasites from both strains were effectively engulfed by DCs, which displayed a full pattern of maturation, in terms of MHC class II and costimulatory molecule expression. In addition, after parasite infection, a limited release of Th1 cytokines was observed. Conclusions: Our results indicate that L. tarentolae could be used as a vehicle for antigen delivery to DCs and to induce the maturation of these cells. The limited cytokine release suggests L. tarentolae as a neutral vaccine vehicle that could be administered in association with appropriate immune-modulating molecules

A 6-amino acid insertion/deletion polymorphism in the mucin domain of TIM-1 confers protections against HIV-1 infection.

Infection of cells by enveloped viruses is a multi-step process requiring both the binding of viral glycoproteins to specific cellular receptors/coreceptors and less specific interactions with accessory molecules whose main function is to locate the virus closer to its receptor(s) [1]. Among such attachment factors, a key role has been attributed to the TIM (T-cell immunoglobulin and mucin domain containing) family receptors, cell surface glycoproteins that control both innate and acquired immune responses during allergy, asthma, tolerance, autoimmunity, as well as viral infections [2]. In the human genome, three genes (HAVCR1, HAVCR2 and TIMD4) encode TIM proteins (TIM-1, TIM-3, and TIM-4, respectively). Structurally, all TIM proteins have a conserved ectodomain consisting of an immunoglobulin (IgV)-like domain and an heavily glycosylated mucin-like domain, anchored to the cell through a transmembrane domain followed by a cytoplasmic tail [3]. TIM-1, in particular, is mostly expressed by hepatocytes and lymphoid cells, preferentially Th2 cells, and is a key T-cell costimulatory molecule that controls T cell activation [4,5]. Human TIM-1, originally identified as the receptor for hepatitis A virus (HAV) [6], promotes the entry of a wide variety of enveloped viruses in host cells [7]. Virus internalization occurs when TIM binds phosphatidylserine (PtdSer) on the viral envelope; this process seems to be independent of viral glycoprotein interaction with cellular receptors [7,8]. A recent analysis of the role of TIM-1 domains indicated that, whereas the IgV domain is essential for virus binding and internalization, the mucin-like domain also plays a key role in enhancing viral entry [8]. Specifically, the use of deletion mutants indicated that a stalk of adequate length is necessary to form an extended structure that places the IgV domain within the appropriate distance from the host cell membrane, thus allowing optimal interactions with the virus [8]. Interestingly, the HAVCR1 gene is highly polymorphic in human populations. In particular, natural selection has maintained high nucleotide diversity in exon 4, which encodes a portion of the mucin-like domain [9]. The selective pressure acting on this region is believed to be virus-mediated, suggesting that polymorphisms in exon 4 modulate viral infection susceptibility and/or diseases severity. In fact, an 18-bp insertion/deletion polymorphism in the exon, causing a six amino acid insertion/deletion variant (157ins/delMTTTVP), was associated with the risk to develop acute liver failure following HAV infection [10]; the same variant was found to modulate AIDS progression in HIV-1 infected subjects [11]. Notably, in both studies the deleted (short) allele of 157ins/delMTTTVP exerted a protective effect. In the HAV study, having one or two copies of the long form of TIM1 was associated with a greater risk to develop severe liver failure, indicating that the protective effect of the short allele is recessive [10]. These data are in line with the observation that the length of the mucin-like domain is critical for enhancing enveloped virus entry [8]. In fact, TIM-1 molecules with a short mucin-like domain (157delMTTTVP) bind HAV less efficiently than those with a long domain (157insMTTTVP) [10]. Herein we assessed whether the HAVCR1 (Hepatitis A virus cellular receptor 1) 18-bp insertion/deletion polymorphism modulates susceptibility to HIV-1 infection in three independent cohorts of HIV-1 exposed seronegative (HESN) individuals. Results indicated that homozygosity for the short allele is associated with natural protection from infection and lower rate of HIV-1 replication in CD4þ T lymphocytesWe investigated whether a 6-amino acid insertion/deletion polymorphism in the mucin domain of TIM-1 (T-cell immunoglobulin and mucin domain 1), modulates susceptibility to HIV-1 infection. The polymorphism was genotyped in three case/control cohorts of HIV-1 exposed seronegative individuals (HESN) and HIV-1 infected subjects from Italy, Peru, and Colombia; data from a Thai population were retrieved from the literature. Across all cohorts, homozygosity for the short TIM-1 allele was more common in HESNs than in HIV-1 infected subjects. A metaanalysis of the four association analyses yielded a p value of 0.005. In vitro infection assays of CD4þ T lymphocytes indicated that homozygosity for the short allele is associated with lower rate of HIV-1 replication. These results suggest that the deletion allele protects from HIV-1 infection with a recessive effect

Characteristic of the study cohorts.

a<p>SD: standard deviation.</p><p>Characteristic of the study cohorts.</p