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Differentiation of CD4 + T cells into either follicular helper T (T FH ) or type 1 helper T (T H 1) cells influences the balance between humoral and cellular adaptive immunity, but the mechanisms whereby pathogens elicit distinct effector cells are incompletely understood. Here we analyzed the spatiotemporal dynamics of CD4 + T cells during infection with recombinant vesicular stomatitis virus (VSV), which induces early, potent neutralizing antibodies, or recombinant lymphocytic choriomeningitis virus (LCMV), which induces a vigorous cellular response but inefficient neutralizing antibodies, expressing the same T cell epitope. Early exposure of dendritic cells to type I interferon (IFN), which occurred during infection with VSV, induced production of the cytokine IL-6 and drove T FH cell polarization, whereas late exposure to type I IFN, which occurred during infection with LCMV, did not induce IL-6 and allowed differentiation into T H 1 cells. Thus, tight spatiotemporal regulation of type I IFN shapes antiviral CD4 + T cell differentiation and might instruct vaccine design strategies. Iannacone and colleagues show that the spatiotemporal regulation of type I interferon expression shapes the differentiation of antiviral CD4 + T cells into T FH or T H 1 cells.

The lysine-specific histone demethylase 1 A (LSD1) is involved in antitumor immunity; however, its role in shaping CD8 + T cell (CTL) differentiation and function remains largely unexplored. Here, we show that pharmacological inhibition of LSD1 (LSD1i) in CTL in the context of adoptive T cell therapy (ACT) elicits phenotypic and functional alterations, resulting in a robust antitumor immunity in preclinical models in female mice. In addition, the combination of anti-PDL1 treatment with LSD1i-based ACT eradicates the tumor and leads to long-lasting tumor-free survival in a melanoma model, complementing the limited efficacy of the immune or epigenetic therapy alone. Collectively, these results demonstrate that LSD1 modulation improves antitumoral responses generated by ACT and anti-PDL1 therapy, providing the foundation for their clinical evaluation. The lysine-specific histone demethylase 1 A (LSD1) can regulate cytotoxic CD8 T cell (CTL) responses and anti-tumor immunity. Here the authors show that ex vivo epigenetic reprogramming with a LSD1 inhibitor enhances cell persistence and anti-tumor activity of adoptively transferred CD8 T cells in preclinical tumor models.

The vaccination campaign against SARS-CoV-2 relies on the world-wide availability of effective vaccines, with a potential need of 20 billion vaccine doses to fully vaccinate the world population. To reach this goal, the manufacturing and logistic processes should be affordable to all countries, irrespective of economical and climatic conditions. Outer membrane vesicles (OMVs) are bacterial-derived vesicles that can be engineered to incorporate heterologous antigens. Given the inherent adjuvanticity, such modified OMVs can be used as vaccines to induce potent immune responses against the associated proteins. Here, we show that OMVs engineered to incorporate peptides derived from the receptor binding motif (RBM) of the spike protein from SARS-CoV-2 elicit an effective immune response in vaccinated mice, resulting in the production of neutralizing antibodies (nAbs) with a titre higher than 1:300. The immunity induced by the vaccine is sufficient to protect the animals from intranasal challenge with SARS-CoV-2, preventing both virus replication in the lungs and the pathology associated with virus infection. Furthermore, we show that OMVs can be effectively decorated with the RBM of the Omicron BA.1 variant and that such engineered OMVs induce nAbs against Omicron BA.1 and BA.5, as measured using the pseudovirus neutralization infectivity assay. Importantly, we show that the RBM438–509 ancestral-OMVs elicited antibodies which efficiently neutralize in vitro both the homologous ancestral strain, the Omicron BA.1 and BA.5 variants with a neutralization titre ranging from 1:100 to 1:1500, suggesting its potential use as a vaccine targeting diverse SARS-CoV-2 variants. Altogether, given the convenience associated with the ease of engineering, production and distribution, our results demonstrate that OMV-based SARS-CoV-2 vaccines can be a crucial addition to the vaccines currently available.

Background Congenital syphilis (CS) depends on the placental transmission of Treponema pallidum (TP) spirochetes from an infected mother to fetus during pregnancy. It shows a wide clinical variability with cutaneous and visceral manifestations, including stillbirths, neonatal death, and asymptomatic cases. Preterm infants with CS may have more severe features of disease than the term ones, due to the combined pathogenic effect of both CS and prematurity. Case presentation We report on a female preterm (32 +6  weeks of gestation) newborn showing most of the typical CS manifestations, in addition to gastrointestinal disorders including feeding difficulties, colon stenosis and malabsorption leading to postnatal growth restriction. The mother resulted positive at the syphilis screening test of the first trimester of pregnancy, but she did not undergo any treatment. At birth, our newborn was VDRL positive (antibody titer four times higher compared to the mother), and she was treated with intravenous benzathine benzylpenicillin G for 10 days (50,000 IU/Kg three times per day). Poor tolerance to enteral nutrition (abdominal distension, increased biliary type gastric secretions) was observed. A barium enema X-Ray identified a colon stenosis within the descending tract. However, the poor general conditions due to a concurrent fungal sepsis did not allow to perform any surgical procedure, and a conservative approach with total parenteral nutrition was started. The following evolution was marked by difficulties in enteral feeding including refusal of food and vomiting, to which also contributed the neurological abnormalities related to a perinatal asphyxia, and the affective deprivation for the physical absence of the mother during hospitalization. At 5 months of age, after the introduction of an amino acid-based formula (Neocate LCP Nutricia ®), an improvement of enteral feeding was observed, with no further and significantly decreased episodes of abdominal distension and vomiting respectively, and regular stool emission. A psychological support offered to the family allowed a more stable bond between the mother and her baby, thus providing a significant additional benefit to food tolerance and growth. She was discharged at 5 months of age, and included in a multidisciplinary follow-up. She at present shows global growth delay, and normal development apart from mildly increased tone of lower limbs. Conclusions Our report highlights less common clinical CS manifestations like gastrointestinal disorders including feeding difficulties, colon stenosis and malabsorption leading to postnatal growth delay. Moreover, it underlines how prematurity may worsen the clinical evolution of such congenital infection, due to the additional pathogenic effect of possible associated diseases and/or conditions like sepsis, hypoxic/ischemic injury, or use of drugs. CS may be observed also in high-income countries, with high rates of antenatal screening and availability of prenatal treatment. A multidisciplinary network must be guaranteed to the affected subjects, to ensure adequate care and improve the quality of life for patients and their families.

Differentiation of CD4.sup.+ T cells into either follicular helper T (T.sub.FH) or type 1 helper T (T.sub.H1) cells influences the balance between humoral and cellular adaptive immunity, but the mechanisms whereby pathogens elicit distinct effector cells are incompletely understood. Here we analyzed the spatiotemporal dynamics of CD4.sup.+ T cells during infection with recombinant vesicular stomatitis virus (VSV), which induces early, potent neutralizing antibodies, or recombinant lymphocytic choriomeningitis virus (LCMV), which induces a vigorous cellular response but inefficient neutralizing antibodies, expressing the same T cell epitope. Early exposure of dendritic cells to type I interferon (IFN), which occurred during infection with VSV, induced production of the cytokine IL-6 and drove T.sub.FH cell polarization, whereas late exposure to type I IFN, which occurred during infection with LCMV, did not induce IL-6 and allowed differentiation into T.sub.H1 cells. Thus, tight spatiotemporal regulation of type I IFN shapes antiviral CD4.sup.+ T cell differentiation and might instruct vaccine design strategies.

Leaf spot disease caused by Cercospora beticola Sacc. (class Ascomycota, ord. Dothideales, fam. Mycosphaerellaceae) is the most destructive foliar disease of sugar beet. Commercial varieties are partially resistant and require repeated fungicide applications to obtain adequate protection levels; this has a high environmental impact and a risk of selecting resistant pathogen strains. A way of reducing chemical inputs could be to use biocontrol agents to replace or supplement fungicide treatments. A well-known class of biological control agents is represented by the fungi belonging to the Trichoderma genus (class Ascomycota, ord. Hypocreales, fam. Hypocreaceae), but there is a lack of information about its behaviour towards C. beticola. This study reports the evaluation of several Trichoderma isolates as possible biocontrol agents of this pathogen. Preliminary in vitro and in vivo assays led to the selection of two Trichoderma isolates characterised by their ability to reduce pathogen sporulation and antagonism towards the pathogen or competence for sugar beet phyllosphere. Repeated foliar applications of the liquid culture homogenate preceded by a single treatment of difenoconazole in 2 year trials under natural inoculum in field reduced the disease incidence and pathogen sporulation from the necrotic spots. An increase in sugar yield was also obtained by means of isolate Ba12/86-based treatments, perhaps due to induced resistance effects.

CD4 T cells play a critical role in antiviral humoral and cellular immune responses. We have previously reported that subcutaneous lymphocytic choriomeningitis virus (s.c. LCMV) infection is characterized by a stark compartmentalization of CD4 T cells, leading to strong T 1 polarization but virtually absent T follicular helper (T ) cells, a key driver of humoral immunity. Here, we investigated the mechanisms responsible for this impaired T differentiation. We found that T-bet cells induced by s.c. LCMV infection encompass a T 1 subset expressing Granzyme-B (GzmB) and a Tcf-1 subset that retains the potential for T differentiation without expressing mature T markers. Interestingly, IFN-γ blockade enables full differentiation of Tcf-1 cells into T , formation of germinal centers and increased antibody production. Of note, the suppression of T cells by IFN-γ is not directly mediated through CD4 T cells but rather involves another cell type, likely dendritic cells (DCs). Our study provides novel insights into the mechanisms directing early CD4 T cell polarization and affecting humoral responses to viruses, laying a foundation for the development of effective vaccine strategies.

TDC are hematopoietic cells that combine dendritic cell (DC) and conventional T cell markers and functional properties. They were identified in secondary lymphoid organs (SLOs) of naïve mice as cells expressing CD11c, major histocompatibility molecule (MHC)-II, and the T cell receptor (TCR) β chain. Despite thorough characterization as to their potential functional properties, a physiological role for TDC remains to be determined. Unfortunately, using CD11c as a marker for TDC has the caveat of its upregulation on different cells, including T cells, upon activation. Therefore, a more specific marker is needed to further investigate TDC functions in peripheral organs in different pathological settings. Here we took advantage of Zbtb46-GFP reporter mice to explore the frequency and localization of TDC in peripheral tissues at steady state and upon viral infection. RNA sequencing analysis confirmed that TDC identified with this reporter model have a gene signature that is distinct from conventional T cells and DC. In addition, frequency and total numbers of TDC in the SLOs recapitulated those found using CD11c as a marker. This reporter model allowed for identification of TDC in situ not only in SLOs but also in the liver and lung of naïve mice. Interestingly, we found that TDC numbers in the SLOs increased upon viral infection, suggesting that TDC might play a role during viral infections. In conclusion, we propose a visualization strategy that might shed light on the physiological role of TDC in several pathological contexts, including infection and cancer.

The lysine-specific histone demethylase 1A (LSD1) has been described to play a role in antitumor immunity; however, the role of LSD1 in shaping CD8+ T cell (CTL) differentiation and function is not understood. Here, we showed that pharmacological inhibition of LSD1 (LSD1i) in CTL elicited phenotypic and functional alterations of the CTL that led to robust antitumor immunity in the context of adoptive T cell therapy (ACT). In addition, the combination of anti-PDL1 therapy with LSD1i-based ACT resulted in a complete tumor eradication and long-lasting tumor-free survival. This study demonstrated that LSD1i together with anti-PDL1 therapy complement each other’s deficiencies and produce a better tumor response in a melanoma model, in which both immune and epigenetic therapy alone have shown limited efficacy. Collectively, these results set the translational potential of modulating LSD1 to improve antitumoral responses generated by ACT and anti-PDL1 therapy, which provide a strong rationale for a combination trial of LSD1i and immunotherapy.

T follicular helper (Tfh) cells are essential for the development of germinal center B cells and high-affinity antibody producing B-cells in human and mice. Here, we identify the guanine nucleotide exchange factor (GEF) Rin-like (Rinl) as a negative regulator of Tfh generation. Loss of Rinl leads to an increase of Tfh in aging, upon in vivo immunization and acute LCMV Armstrong infection in mice, and in human CD4+ T cell in vitro cultures. Further, adoptive transfer experiments using WT and Rinl-KO naive CD4+ T cells unraveled T cell-intrinsic functions of Rinl. Mechanistically, Rinl regulates CD28 internalization and signaling, thereby shaping CD4+ T cell activation and differentiation. Thus, our results identify the GEF Rinl as a negative regulator of global Tfh differentiation in an immunological context and species- independent manner, and furthermore connect Rinl with CD28 internalization and signaling pathways in CD4+ T cells, demonstrating for the first-time the importance of endocytic processes for Tfh differentiation. Competing Interest Statement The authors have declared no competing interest.