Single genetic mutations predispose to very early onset inflammatory bowel disease (VEO-IBD). Here, we identify a de novo duplication of the 10p15.1 chromosomal region, including the IL2RA locus, in a 2-year-old girl with treatment-resistant pancolitis that was brought into remission by colectomy. Strikingly, after colectomy while the patient was in clinical remission and without medication, the peripheral blood CD4:CD8 ratio was constitutively high and CD25 expression was increased on circulating effector memory, Foxp3+, and Foxp3neg CD4+ T cells compared to healthy controls. This high CD25 expression increased IL-2 signaling, potentiating CD4+ T-cell-derived IFNγ secretion after T-cell receptor (TCR) stimulation. Restoring CD25 expression using the JAK1/3-inhibitor tofacitinib controlled TCR-induced IFNγ secretion in vitro. As diseased colonic tissue, but not the unaffected duodenum, contained mainly CD4+ T cells with a prominent IFNγ-signature, we hypothesize that local microbial stimulation may have initiated colonic disease. Overall, we identify that duplication of the IL2RA locus can associate with VEO-IBD and suggest that increased IL-2 signaling predisposes to colonic intestinal inflammation.
© 2021. The Author(s).

NF-κB2/p100 (p100) is an inhibitor of κB (IκB) protein that is partially degraded to produce the NF-κB2/p52 (p52) transcription factor. Heterozygous NFKB2 mutations cause a human syndrome of immunodeficiency and autoimmunity, but whether autoimmunity arises from insufficiency of p52 or IκB function of mutated p100 is unclear. Here, we studied mice bearing mutations in the p100 degron, a domain that harbors most of the clinically recognized mutations and is required for signal-dependent p100 degradation. Distinct mutations caused graded increases in p100-degradation resistance. Severe p100-degradation resistance, due to inheritance of one highly degradation-resistant allele or two subclinical alleles, caused thymic medullary hypoplasia and autoimmune disease, whereas the absence of p100 and p52 did not. We inferred a similar mechanism occurs in humans, as the T cell receptor repertoires of affected humans and mice contained a hydrophobic signature of increased self-reactivity. Autoimmunity in autosomal dominant NFKB2 syndrome arises largely from defects in nonhematopoietic cells caused by the IκB function of degradation-resistant p100.
© 2020 Wirasinha et al.

Advancements in science enable researchers to constantly innovate and create novel biologics. However, the use of non-human animal models during the development of biologics impedes identification of precise in vivo interactions between the human immune system and treatments. Due to lack of this understanding, adverse effects are frequently observed in healthy volunteers and patients exposed to potential biologics during clinical trials. In this study, we evaluated and compared the effects of known immunotoxic biologics, Proleukin®/IL-2 and OKT3 in humanized mice (reconstituted with human fetal cells) to published clinical outcomes. We demonstrated that humanized mice were able to recapitulate in vivo pathological changes and human-specific immune responses, such as elevated cytokine levels and modulated lymphocytes and myeloid subsets. Given the high similarities of immunological side effects observed between humanized mice and clinical studies, this model could be used to assess immunotoxicity of biologics at a pre-clinical stage, without placing research participants and/or patients at risk.
Copyright © 2020 Yong, Her, Tan, Tan, Liu, Lai, Heng, Fan, Chang, Wang, Chan, Chen and Chen.

Pulmonary epithelial cells play a crucial role in host defense against bacterial insult. However, the innate immunity in pulmonary epithelium is relatively less characterized than that of professional immune cells. In the current study, we investigated IL-8 induction by bacterial cell wall components in human lung epithelial A549 cells and primary human bronchial epithelial cells. We found that lipoproteins are the most potent IL-8 inducers among bacterial cell wall components. Using synthetic lipopeptides that mimic bacterial lipoprotein pam2CSK4 and pam3CSK4, we further investigated signal transduction mechanism. Interestingly, IL-8 secretion appeared higher upon diacylated pam2CSK4 treatment than triacylated pam3CSK4. A role of TLR2 in lipopeptide-induced IL-8 secretion was monitored by siRNA transfection and functional blocking antibodies. We found that TLR2 in A549 cell localizes to intracellular compartment. Activation mechanism for the intracellular TLR2 differed between pam2CSK4 and pam3CSK4. Pam2CSK4 utilized a lipid-raft dependent mechanism while pam3CSK4 utilizes clathrin-dependnet endocytosis. Using CHO/CD14/TLR2 cell line, we found the distinct IL-8 induction level initiates at the receptor activation level. Subsequent pharmacological inhibitor studies showed that pam2CSK4 and pam3CSK4 utilizes different MAPK pathways. Downstream transcription factor activation was determined by electro-mobility shift assay (EMSA) and luciferase reporter assays. The results showed distinct pattern of activation for NF-κB, NF-IL6 and AP-1 from human IL-8 promoter. These results suggest that bacterial lipoproteins from cell walls are an important determinant in initiating tissue inflammation in pulmonary epithelium upon bacterial insult.

Treatment with immune checkpoint blockade (ICB) has revolutionized cancer therapy. Until now, predictive biomarkers1-10 and strategies to augment clinical response have largely focused on the T cell compartment. However, other immune subsets may also contribute to anti-tumour immunity11-15, although these have been less well-studied in ICB treatment16. A previously conducted neoadjuvant ICB trial in patients with melanoma showed via targeted expression profiling17 that B cell signatures were enriched in the tumours of patients who respond to treatment versus non-responding patients. To build on this, here we performed bulk RNA sequencing and found that B cell markers were the most differentially expressed genes in the tumours of responders versus non-responders. Our findings were corroborated using a computational method (MCP-counter18) to estimate the immune and stromal composition in this and two other ICB-treated cohorts (patients with melanoma and renal cell carcinoma). Histological evaluation highlighted the localization of B cells within tertiary lymphoid structures. We assessed the potential functional contributions of B cells via bulk and single-cell RNA sequencing, which demonstrate clonal expansion and unique functional states of B cells in responders. Mass cytometry showed that switched memory B cells were enriched in the tumours of responders. Together, these data provide insights into the potential role of B cells and tertiary lymphoid structures in the response to ICB treatment, with implications for the development of biomarkers and therapeutic targets.