Leverage research EXCELLence and INNOVation potential of Instituto de Medicina Molecular (IMM) through translational biomedical research in immunity and infection.

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Publications

Intestinal barrier interactions with specialized CD8 T Cells

Publication . Konjar, Spela; Ferreira, Cristina; Blankenhaus, Birte; Veldhoen, Marc

The trillions of microorganisms that reside in the gastrointestinal tract, essential for nutrient absorption, are kept under control by a single cell barrier and large amounts of immune cells. Intestinal epithelial cells (IECs) are critical in establishing an environment supporting microbial colonization and immunological tolerance. A large population of CD8+ T cells is in direct and constant contact with the IECs and the intraepithelial lymphocytes (IELs). Due to their location, at the interphase of the intestinal lumen and external environment and the host tissues, they seem ideally positioned to balance immune tolerance and protection to preserve the fragile intestinal barrier from invasion as well as immunopathology. IELs are a heterogeneous population, with a large innate-like contribution of unknown specificity, intercalated with antigen-specific tissue-resident memory T cells. In this review, we provide a comprehensive overview of IEL physiology and how they interact with the IECs and contribute to immune surveillance to preserve intestinal homeostasis and host-microbial relationships.

2017Journal article

Open access

Academic labs supporting COVID‐19 diagnostics

Publication . Veldhoen, Marc; Zuzarte-Luis, Vanessa

Despite news about the new virus SARS-CoV-2 and COVID-19 grabbing the headlines in the beginning of 2020, life and work carried on as normal in most academic labs. Lab projects were the focus, results discussed face-to-face and hypothesis dismissed. Conferences were attended in person and flights to the next meeting often booked already. By March, the seriousness became clear. With surrounding countries reporting increasing number of infections, the emergence of SARS-CoV-2 in Portugal was a matter of time, with the first two Portuguese cases reported at the start of March. Newspapers reported the cases with warnings not to be alarmist and that officials would calmly follow the evolution of the events (see here). However, how do you follow the spread of a virus, especially when it is new and capacity to detect it is limited?

2021Journal article

Restricted access

Intestinal tissue-resident T cell activation depends on metabolite availability

Publication . Konjar, Spela; Ferreira, Cristina; Carvalho, Filipa; Figueiredo-Campos, Patricia; Fanczal, Júlia; Ribeiro, Sofia; Morais, Vanessa A.; Veldhoen, Marc

The metabolic capacity of many cells is tightly regulated and can adapt to changes in metabolic resources according to environmental changes. Tissue-resident memory (TRM) CD8+ T cells are one of the most abundant T cell populations and offer rapid protection against invading pathogens, especially at the epithelia. TRM cells metabolically adapt to their tissue niche, such as the intestinal epithelial barrier. In the small intestine, the types of TRM cells are intraepithelial lymphocytes (IELs), which contain high levels of cytotoxic molecules and express activation markers, suggesting a heightened state of activation. We hypothesize that the tissue environment may determine IEL activity. We show that IEL activation, in line with its semiactive status, is metabolically faster than circulating CD8+ T cells. IEL glycolysis and oxidative phosphorylation (OXPHOS) are interdependently regulated and are dependent on rapid access to metabolites from the environment. IELs are restrained by local availability of metabolites, but, especially, glucose levels determine their activity. Importantly, this enables functional control of intestinal TRM cells by metabolic means within the fragile environment of the intestinal epithelial barrier.

2022Journal article

Open access

Seroprevalence of anti‐SARS‐CoV‐2 antibodies in COVID‐19 patients and healthy volunteers up to 6 months post disease onset

Publication . Figueiredo-Campos, Patricia; Blankenhaus, Birte; Mota, Catarina; Gomes, Andreia; Serrano, Marta; Ariotti, Silvia; Costa, Catarina; Nunes-Cabaço, Helena; Mendes, António M.; Gaspar, Pedro; Pereira‐Santos, M. Conceição; Rodrigues, Fabiana; Condeço, Jorge; Escoval, M. Antonia; Santos, Matilde; Ramirez, Mário; Cristino, José Melo; Simas, J Pedro; Vasconcelos, Eugenia; Afonso, Ângela; Veldhoen, Marc

SARS-CoV-2 has emerged as a human pathogen, causing clinical signs, from fever to pneumonia-COVID-19-but may remain mild or asymptomatic. To understand the continuing spread of the virus, to detect those who are and were infected, and to follow the immune response longitudinally, reliable and robust assays for SARS-CoV-2 detection and immunological monitoring are needed. We quantified IgM, IgG, and IgA antibodies recognizing the SARS-CoV-2 receptor-binding domain (RBD) or the Spike (S) protein over a period of 6 months following COVID-19 onset. We report the detailed setup to monitor the humoral immune response from over 300 COVID-19 hospital patients and healthcare workers, 2500 University staff, and 198 post-COVID-19 volunteers. Anti-SARS-CoV-2 antibody responses follow a classic pattern with a rapid increase within the first three weeks after symptoms. Although titres reduce subsequently, the ability to detect anti-SARS-CoV-2 IgG antibodies remained robust with confirmed neutralization activity for up to 6 months in a large proportion of previously virus-positive screened subjects. Our work provides detailed information for the assays used, facilitating further and longitudinal analysis of protective immunity to SARS-CoV-2. Importantly, it highlights a continued level of circulating neutralising antibodies in most people with confirmed SARS-CoV-2.

2020Journal article

Open access

A rapid real-time polymerase chain reaction-based live virus microneutralization assay for detection of neutralizing antibodies against SARS-CoV-2 in blood/serum

Publication . Abidi, Syed Hani; Imtiaz, Kehkashan; Kanji, Akbar; Qaiser, Shama; Khan, Erum; Iqbal, Kiran; Veldhoen, Marc; Ghias, Kulsoom; Simas, J Pedro; Hasan, Zahra

Background: Individuals recovering from COVID-19 are known to have antibodies against the Spike and other structural proteins. Antibodies against Spike have been shown to display viral neutralization. However, not all antibodies against Spike have neutralizing ability although they may be cross-reactive. There is a need for easy-to-use SARS-CoV-2 neutralizing assays for the determination of virus-neutralizing activity in sera of individuals. Here we describe a PCR-based micro-neutralization assay that can be used to evaluate the viral neutralization titers of serum from SARS-CoV-2 infected individuals. Methods: The SARS-CoV-2 strain used was isolated from a nasopharyngeal specimen of a COVID-19 case. The limiting dilution method was used to obtain a 50% tissue culture infective dose (TCID50) of Vero cells. For the micro-neutralization assay, 19 serum samples, with positive IgG titers against Spike Receptor-Binding Domain (RBD) were tested. After 24 hours, infected cells were inspected for the presence of a cytopathic effect, lysed and RNA RT-PCR conducted for SARS-CoV-2. PCR target Ct values were used to calculate percent neutralization/inhibition of SARS-CoV-2. Results: Out of 19 samples, 13 samples gave 100% neutralization at all dilutions, 1 sample showed neutralization at the first dilution, 4 samples showed neutralization at lower dilutions, while one sample did not demonstrate any neutralization. The RBD ODs and neutralization potential percentages were found to be positively correlated. Conclusion: We describe a rapid RT-PCR-based SARS-CoV-2 microneutralization assay for the detection of neutralizing antibodies. This can effectively be used to test the antiviral activity of serum antibodies for the investigation of both disease-driven and vaccine-induced responses.

2021Journal article

Open access