Understanding the mechanisms that modulate T helper lymphocyte functions is crucial to decipher normal and pathogenic immune responses in humans. To identify molecular determinants influencing the pathogenicity of T cells, we separated ex vivo -isolated primary human memory T lymphocytes based on their ability to produce high levels of inflammatory cytokines. We found that the inflammatory, cytokine-producing phenotype of memory T lymphocytes was defined by a specific core gene signature and was mechanistically regulated by the constitutive activation of the NF-κB pathway and by the expression of the transcriptional repressor BHLHE40. BHLHE40 attenuated the expression of anti-inflammatory factors, including miR-146a, a negative regulator of NF-κB activation, and ZC3H12D, an RNase of the Regnase-1 family able to degrade inflammatory transcripts. Our data reveal a molecular network regulating the pro-inflammatory phenotype of human memory T lymphocytes, with the potential to contribute to disease.

Very small embryonic-like cells (VSELs) are a population of very rare pluripotent stem cells isolated in adult murine bone marrow and many other tissues and organs, including umbilical cord blood (UCB). VSEL existence is still not universally accepted by the scientific community, so for this purpose, we sought to investigate whether presumptive VSELs (pVSELs) could be isolated from human UCB with an improved protocol based on the isolation of enriched progenitor cells by depletion of nonprogenitor cells with magnetic separation. Progenitor cells, likely including VSELs, cultured with retinoic acid were able to form dense colonies and cystic embryoid bodies and to differentiate toward the ecto-meso-endoderm lineages as shown by the positivity to specific markers. VSEL differentiative potential toward mesodermal lineage was further demonstrated in vitro upon exposure to an established inductive protocol, which induced the acquisition of renal progenitor cell phenotype. VSEL-derived renal progenitors showed regenerative potential in a cisplatin model of acute kidney injury by restoring renal function and tubular structure through induction of proliferation of endogenous renal cells. The data presented here foster the great debate that surrounds VSELs and, more in general, the existence of cells endowed with pluripotent features in adult tissues. In fact, the possibility to find and isolate subpopulations of cells that fully fit all the criteria utilized to define pluripotency remains, nowadays, almost unproven. Thus, efforts to better characterize the phenotype of these intriguing cells are crucial to understand their possible applications for regenerative and precision medicine purposes.

IFN-β treatment is a commonly used therapy for relapsing-remitting multiple sclerosis (MS), while vitamin D deficiency correlates with an increased risk of MS and/or its activity. MS is a demyelinating chronic inflammatory disease of the central nervous system, in which activated T lymphocytes play a major role, and may represent direct targets of IFN-β and vitamin D activities. However, the underlying mechanism of action of vitamin D and IFN-β, alone or in combination, remains incompletely understood, especially when considering their direct effects on the ability of T lymphocytes to produce inflammatory cytokines. We profiled the expression of immune-related genes and microRNAs in primary human T lymphocytes in response to vitamin D and IFN-β, and we dissected the impact of these treatments on cytokine production and T cell proliferation. We found that the treatments influenced primarily memory T cell plasticity, rather than polarization toward a stable phenotype. Moreover, our data revealed extensive reprogramming of the transcriptional output of primary T cells in response to vitamin D and IFN-β and provide the bases for further mechanistic insights into these commonly used treatments.