Novel evidence of Thymosin α1 immunomodulatory properties in SARS-CoV-2 infection: effect on innate inflammatory response in a peripheral blood mononuclear cell-based in vitro model

Graphical abstract The peculiar property of Thymosin alpha 1 (Tα1) to act as master regulator of immune homeostasis has been successfully defined in different physiological and pathological contexts ranging from cancer to infection. Interestingly, recent papers also demonstrated its mitigating effect on the "cytokine storm” as well as on the T-cell exhaustion/activation in SARS-CoV-2 infected individuals. Nevertheless, in spite of the increasing knowledge on Tα1-induced effects on T cell response confirming the distinctive features of this multifaceted peptide, little is known on its effects on innate immunity to SARS-CoV-2 infection. Here, we interrogated peripheral blood mononuclear cell (PBMC) cultures stimulated with SARS-CoV-2 to disclose Tα1 properties on the main cell players of early response to infection, namely monocytes and myeloid dendritic cells (mDC). Moving from ex vivo data showing an enhancement in the frequency of inflammatory monocytes and activated mDC in COVID-19 patients, a PBMC-based experimental setting reproduced in vitro a similar profile with an increased percentage of CD16+ inflammatory monocytes and mDC expressing CD86 and HLA-DR activation markers in response to SARS-CoV-2 stimulation. Interestingly, the treatment of SARS-CoV-2-stimulated PBMC with Tα1 dampened the inflammatory/activation status of both monocytes and mDC by reducing the release of pro-inflammatory mediators, including TNF-α, IL-6 and IL-8, while promoting the production of the anti-inflammatory cytokine IL-10. This study further clarifies the working hypothesis on Tα1 mitigating action on COVID-19 inflammatory condition. Moreover, these evidence shed light on inflammatory pathways and cell types involved in acute SARS-CoV-2 infection and likely targetable by newly immune-regulating therapeutic approaches.

Novel evidence of Thymosin α1 immunomodulatory properties in SARS-CoV-2 infection: Effect on innate inflammatory response in a peripheral blood mononuclear cell-based in vitro model.

The peculiar property of Thymosin alpha 1 (Tα1) to act as master regulator of immune homeostasis has been successfully defined in different physiological and pathological contexts ranging from cancer to infection. Interestingly, recent papers also demonstrated its mitigating effect on the "cytokine storm" as well as on the T-cell exhaustion/activation in SARS-CoV-2 infected individuals. Nevertheless, in spite of the increasing knowledge on Tα1-induced effects on T cell response confirming the distinctive features of this multifaceted peptide, little is known on its effects on innate immunity during SARS-CoV-2 infection. Here, we interrogated peripheral blood mononuclear cell (PBMC) cultures stimulated with SARS-CoV-2 to disclose Tα1 properties on the main cell players of early response to infection, namely monocytes and myeloid dendritic cells (mDC). Moving from ex vivo data showing an enhancement in the frequency of inflammatory monocytes and activated mDC in COVID-19 patients, a PBMC-based experimental setting reproduced in vitro a similar profile with an increased percentage of CD16+ inflammatory monocytes and mDC expressing CD86 and HLA-DR activation markers in response to SARS-CoV-2 stimulation. Interestingly, the treatment of SARS-CoV-2-stimulated PBMC with Tα1 dampened the inflammatory/activation status of both monocytes and mDC by reducing the release of pro-inflammatory mediators, including TNF-α, IL-6 and IL-8, while promoting the production of the anti-inflammatory cytokine IL-10. This study further clarifies the working hypothesis on Tα1 mitigating action on COVID-19 inflammatory condition. Moreover, these evidence shed light on inflammatory pathways and cell types involved in acute SARS-CoV-2 infection and likely targetable by newly immune-regulating therapeutic approaches.

A specific anti-COVID-19 BNT162b2 vaccine-induced early innate immune signature positively correlates with the humoral protective response in healthy and multiple sclerosis vaccine recipients.

Objectives: The very rapidly approved mRNA-based vaccines against SARS-CoV-2 spike glycoprotein, including Pfizer-BioNTech BNT162b2, are effective in protecting from severe coronavirus disease 2019 (COVID-19) in immunocompetent population. However, establishing the duration and identifying correlates of vaccine-induced protection will be crucial to optimise future immunisation strategies. Here, we studied in healthy vaccine recipients and people with multiple sclerosis (pwMS), undergoing different therapies, the regulation of innate immune response by mRNA vaccination in order to correlate it with the magnitude of vaccine-induced protective humoral responses. Methods: Healthy subjects (n = 20) and matched pwMS (n = 22) were longitudinally sampled before and after mRNA vaccination. Peripheral blood mononuclear cell (PBMC)-associated type I and II interferon (IFN)-inducible gene expression, serum innate cytokine/chemokine profile as well as binding and neutralising anti-SARS-COV-2 antibodies (Abs) were measured. Results: We identified an early immune module composed of the IFN-inducible genes Mx1, OAS1 and IRF1, the serum cytokines IL-15, IL-6, TNF-α and IFN-γ and the chemokines IP-10, MCP-1 and MIG, induced 1 day post second and third BNT162b2 vaccine doses, strongly correlating with magnitude of humoral response to vaccination in healthy and MS vaccinees. Moreover, induction of the early immune module was dramatically affected in pwMS treated with fingolimod and ocrelizumab, both groups unable to induce a protective humoral response to COVID-19 vaccine. Conclusion: Overall, this study suggests that the vaccine-induced early regulation of innate immunity is mediated by IFN signalling, impacts on the magnitude of adaptive responses and it might be indicative of vaccine-induced humoral protection.

Neurodevelopmental Outcomes in Preterm Infants Receiving a Multicomponent vs. a Soybean-Based Lipid Emulsion: 24 Month Follow-Up of a Randomized Controlled Trial.

BACKGROUND: Few studies in the literature have analyzed the long-term neurodevelopmental outcomes of the administration of a multicomponent versus a soybean-based lipid emulsion (LE) in preterm infants receiving parenteral nutrition (PN). A recent randomized controlled trial conducted in our unit provided evidence of better growth in head circumference during the hospital stay in those who received a multicomponent LE. METHODS: This is a 24 month follow-up study of preterm infants, previously enrolled in a randomized trial, who received a multicomponent LE (SMOFlipid®) or a standard soybean-based one (Intralipid®). We evaluated neurodevelopmental outcomes at 24 months of corrected age (CA) in the two groups. RESULTS: Ninety-three children were followed up to the age of 24 months CA. Due to the peculiar time frame of the SARS-CoV-2 pandemic, neurodevelopmental outcomes were evaluated only in 77 children: 37 in the SMOFlipid® group and 40 in the Intralipid® group. No differences in major disability rates or in Griffith's evaluation were found between the two groups. CONCLUSIONS: In our population study, the administration of a multicomponent LE containing fish oil, compared to a soybean-based LE, had no significant effects on neurodevelopmental outcomes in preterm infants at 24 months CA.

Short- and mid-term multidisciplinary outcomes of newborns exposed to SARS-CoV-2 in utero or during the perinatal period: preliminary findings.

The long-term outcomes of newborns exposed to SARS-CoV-2 infection in utero or during the first hours of life are still unknown. We performed a single-center, prospective, observational study of newborns born from mothers with microbiologically confirmed SARS-CoV-2 infection in pregnancy or at time of delivery. Infants were offered a multidisciplinary follow-up consisting of nasopharyngeal Polymerase Chain Reaction test at birth and at 48-72 h of life, auxological growth and neurological development, serologic testing, and audiological and ophthalmological assessments. One-hundred ninety-eight mothers and 199 newborns were enrolled. Of the 199 newborns, 171 underwent nasopharyngeal swab, four (2.3%) and two (1.15%) children tested positive at birth and 48-72 h of life, respectively. None had SARS-CoV-2 related symptoms. Auxologic and neurologic development were normal in all children during follow-up. Nine out of 59 infants had SARS-CoV-2 IgG at 3 months of life, which was associated with a positive nasopharyngeal swab at birth (P = 0.04). Twenty seven out of 143 (18.8%) newborns had pathologic transitory evoked otoacoustic emissions at birth, although 14/27 repeated after 1 month were normal. Audiological evaluation was completed with Auditory Brainstem Response between the third and sixth month of life in 34 children, showing in all normal hearing threshold. The ophthalmological evaluation found retinal vascular anomalies in 3/20 (15%) children, immature visual acuity in 5/20 (25%) children, and reduced distance attention in 6/20 cases (30%). CONCLUSIONS: Our study showed that the neonatal and mid-term multidisciplinary outcomes of newborns exposed to SARS-CoV-2 infection in utero or during the first hours of life are mostly positive, with the exception of ophthalmologic findings which, in a preliminary cohort, were abnormal in about 15% of cases. Further prospective, longitudinal studies are needed to better understand the clinical outcomes of children exposed to SARS-CoV-2 in utero and in the early postnatal life. WHAT IS KNOWN: • In utero mother-to-child transmission of SARS-CoV-2 has been documented by several independent studies. • Neonatal COVID-19 is a systemic disease that can be severe, although rarely. WHAT IS NEW: • Newborns exposed in utero to SARS-CoV-2 have mostly a normal auxological, audiological, and neurological development during the first months of life. • Fundus fluorescein angiography revealed that up to 5% of newborns exposed in utero to SARS-CoV2 can show retinal and choroidal abnormalities, including peripheral hypofluorescence of the choroid and increased vascular tortuosity.

Differential plasmacytoid dendritic cell phenotype and type I Interferon response in asymptomatic and severe COVID-19 infection.

SARS-CoV-2 fine-tunes the interferon (IFN)-induced antiviral responses, which play a key role in preventing coronavirus disease 2019 (COVID-19) progression. Indeed, critically ill patients show an impaired type I IFN response accompanied by elevated inflammatory cytokine and chemokine levels, responsible for cell and tissue damage and associated multi-organ failure. Here, the early interaction between SARS-CoV-2 and immune cells was investigated by interrogating an in vitro human peripheral blood mononuclear cell (PBMC)-based experimental model. We found that, even in absence of a productive viral replication, the virus mediates a vigorous TLR7/8-dependent production of both type I and III IFNs and inflammatory cytokines and chemokines, known to contribute to the cytokine storm observed in COVID-19. Interestingly, we observed how virus-induced type I IFN secreted by PBMC enhances anti-viral response in infected lung epithelial cells, thus, inhibiting viral replication. This type I IFN was released by plasmacytoid dendritic cells (pDC) via an ACE-2-indipendent but Neuropilin-1-dependent mechanism. Viral sensing regulates pDC phenotype by inducing cell surface expression of PD-L1 marker, a feature of type I IFN producing cells. Coherently to what observed in vitro, asymptomatic SARS-CoV-2 infected subjects displayed a similar pDC phenotype associated to a very high serum type I IFN level and induction of anti-viral IFN-stimulated genes in PBMC. Conversely, hospitalized patients with severe COVID-19 display very low frequency of circulating pDC with an inflammatory phenotype and high levels of chemokines and pro-inflammatory cytokines in serum. This study further shed light on the early events resulting from the interaction between SARS-CoV-2 and immune cells occurring in vitro and confirmed ex vivo. These observations can improve our understanding on the contribution of pDC/type I IFN axis in the regulation of the anti-viral state in asymptomatic and severe COVID-19 patients.

Innate Immune Response to SARS-CoV-2 Infection: From Cells to Soluble Mediators.

The vulnerability of humankind to SARS-CoV-2 in the absence of a pre-existing immunity, the unpredictability of the infection outcome, and the high transmissibility, broad tissue tropism, and ability to exploit and subvert the immune response pose a major challenge and are likely perpetuating the COVID-19 pandemic. Nevertheless, this peculiar infectious scenario provides researchers with a unique opportunity for studying, with the latest immunological techniques and understandings, the immune response in SARS-CoV-2 naïve versus recovered subjects as well as in SARS-CoV-2 vaccinees. Interestingly, the current understanding of COVID-19 indicates that the combined action of innate immune cells, cytokines, and chemokines fine-tunes the outcome of SARS-CoV-2 infection and the related immunopathogenesis. Indeed, the emerging picture clearly shows that the excessive inflammatory response against this virus is among the main causes of disease severity in COVID-19 patients. In this review, the innate immune response to SARS-CoV-2 infection is described not only in light of its capacity to influence the adaptive immune response towards a protective phenotype but also with the intent to point out the multiple strategies exploited by SARS-CoV-2 to antagonize host antiviral response and, finally, to outline inborn errors predisposing individuals to COVID-19 disease severity.