Magnitude of venous or capillary blood-derived SARS-CoV-2-specific T cell response determines COVID-19 immunity.

T cells specific for SARS-CoV-2 are thought to protect against infection and development of COVID-19, but direct evidence for this is lacking. Here, we associated whole-blood-based measurement of SARS-CoV-2-specific interferon-γ-positive T cell responses with positive COVID-19 diagnostic (PCR and/or lateral flow) test results up to 6 months post-blood sampling. Amongst 148 participants donating venous blood samples, SARS-CoV-2-specific T cell response magnitude is significantly greater in those who remain protected versus those who become infected (P < 0.0001); relatively low magnitude T cell response results in a 43.2% risk of infection, whereas high magnitude reduces this risk to 5.4%. These findings are recapitulated in a further 299 participants testing a scalable capillary blood-based assay that could facilitate the acquisition of population-scale T cell immunity data (14.9% and 4.4%, respectively). Hence, measurement of SARS-CoV-2-specific T cells can prognosticate infection risk and should be assessed when monitoring individual and population immunity status.

Prognostic significance of interleukin-17A-producing colorectal tumour antigen-specific T cells.

BACKGROUND: The T cell cytokine profile is a key prognostic indicator of post-surgical outcome for colorectal cancer (CRC). Whilst TH1 (IFN-γ+) cell-mediated responses generated in CRC are well documented and are associated with improved survival, antigen-specific TH17 (IL-17A+) responses have not been similarly measured. METHODS: We sought to determine the cytokine profile of circulating tumour antigen-(5T4/CEA) specific T cells of 34 CRC patients to address whether antigen-specific IL-17A responses were detectable and whether these were distinct to IFN-γ responses. RESULTS: As with IFN-γ-producing T cells, anti-5T4/CEA TH17 responses were detectable predominantly in early stage (TNM I/II) CRC patients. Moreover, whilst IL-17A was always produced in association with IFN-γ, this release was mainly from two distinct T cell populations rather than by 'dual producing' T cells. Patients mounting both tumour-specific TH1+/TH17+ responses exhibited prolonged relapse-free survival. CONCLUSIONS: Tumour antigen-specific TH17 responses play a beneficial role in preventing post-operative colorectal tumour recurrence.

Cancer Antigen Discovery Is Enabled by RNA Sequencing of Highly Purified Malignant and Nonmalignant Cells.

PURPOSE: Broadly expressed, highly differentiated tumor-associated antigens (TAA) can elicit antitumor immunity. However, vaccines targeting TAAs have demonstrated disappointing clinical results, reflecting poor antigen selection and/or immunosuppressive mechanisms. EXPERIMENTAL DESIGN: Here, a panel of widely expressed, novel colorectal TAAs were identified by performing RNA sequencing of highly purified colorectal tumor cells in comparison with patient-matched colonic epithelial cells; tumor cell purification was essential to reveal these genes. Candidate TAA protein expression was confirmed by IHC, and preexisting T-cell immunogenicity toward these antigens tested. RESULTS: The most promising candidate for further development is DNAJB7 [DnaJ heat shock protein family (Hsp40) member B7], identified here as a novel cancer-testis antigen. It is expressed in many tumors and is strongly immunogenic in patients with cancers originating from a variety of sites. DNAJB7-specific T cells were capable of killing colorectal tumor lines in vitro, and the IFNγ+ response was markedly magnified by control of immunosuppression with cyclophosphamide in patients with cancer. CONCLUSIONS: This study highlights how prior methods that sequence whole tumor fractions (i.e., inclusive of alive/dead stromal cells) for antigen identification may have limitations. Through tumor cell purification and sequencing, novel candidate TAAs have been identified for future immunotherapeutic targeting.

The Ussing chamber system for measuring intestinal permeability in health and disease.

BACKGROUND: The relationship between intestinal epithelial integrity and the development of intestinal disease is of increasing interest. A reduction in mucosal integrity has been associated with ulcerative colitis, Crohn's disease and potentially could have links with colorectal cancer development. The Ussing chamber system can be utilised as a valuable tool for measuring gut integrity. Here we describe step-by-step methodology required to measure intestinal permeability of both mouse and human colonic tissue samples ex vivo, using the latest equipment and software. This system can be modified to accommodate other tissues. METHODS: An Ussing chamber was constructed and adapted to support both mouse and human tissue to measure intestinal permeability, using paracellular flux and electrical measurements. Two mouse models of intestinal inflammation (dextran sodium sulphate treatment and T regulatory cell depletion using C57BL/6-FoxP3DTR mice) were used to validate the system along with human colonic biopsy samples. RESULTS: Distinct regional differences in permeability were consistently identified within mouse and healthy human colon. In particular, mice showed increased permeability in the mid colonic region. In humans the left colon is more permeable than the right. Furthermore, inflammatory conditions induced chemically or due to autoimmunity reduced intestinal integrity, validating the use of the system. CONCLUSIONS: The Ussing chamber has been used for many years to measure barrier function. However, a clear and informative methods paper describing the setup of modern equipment and step-by-step procedure to measure mouse and human intestinal permeability isn't available. The Ussing chamber system methodology we describe provides such detail to guide investigation of gut integrity.

Podoplanin lymphatic density and invasion correlate with adverse clinicopathologic and biological factors and survival in neuroblastomas.

Neuroblastoma (NB) is a challenging problem in oncology, as the majority of patients have lymphatic and/or hematogenous metastases at diagnosis. We investigated the prognostic significance of lymphatic density (LD) and invasion (LI) in NBs using the lymphatic endothelial marker podoplanin (PDPN). A total of 77 neuroblastic tumors and 9 ganglioneuromas (GNs) were immunostained for PDPN using D2-40 antibody. Intratumoral lymphatics were identified in 87% (67/77) of NBs and 7/9 GNs. The LD counts were significantly higher (P<0.01) in NBs (median=19.6, range=0.00 to 89.3) than in GNs (median=10.2, range=0 to 18.7). LI, assessed in D2-40-stained lymphatics, was present in 52/67 (78%) NBs. LDs were significantly higher in NBs from patients with adverse clinical factors (advanced-stage, high-risk group, primary abdominal compared with extra-abdominal sites), biological factors (MYCN amplification, 1p deletion, 17q gain), and distant lymph node metastases. LDs and LI were also significantly higher in NBs belonging to an unfavorable pathology prognostic group and in those with a high mitosis-karyorrhexis index. High LD and the presence of LI correlated with a shorter event-free survival in univariable analyses. High LD and the presence of LI were also associated with worse overall survival, although the association was less strong. In conclusion, increased LDs and the presence of LI correlated with adverse clinicopathologic and biological factors and survival. These findings suggest that PDPN has the potential to provide valuable prognostic information to clinicians for risk assessment in NBs.

PROX1 lymphatic density correlates with adverse clinicopathological factors, lymph node metastases and survival in neuroblastomas.

Increased lymphatic density correlates with lymph node metastases and survival in some epithelial cancers. The transcription factor, Prospero-related homeobox-gene 1, PROX1, plays an important role in the differentiation and proliferation of the lymphatic and nervous systems. We studied the clinicopathological significance of PROX1 expression in neuroblastomas (NBs) as the majority of patients have lymphatic and/or haematogenous metastases at diagnosis. PROX1-immunostained lymphatic vessels were present in 40/69 (58%) of NBs and 1/6 benign ganglioneuromas (GNs). Lymphatic density (LD) counts were significantly increased in NBs from patients with unfavourable clinical and pathological factors, and with distant lymph node metastases (LNM). Lymphatic invasion (LI) by tumoral emboli was present in 27/40 (68%) of NBs. A significantly higher proportion of LI was seen in undifferentiated/poorly-differentiated, (UD/PD) compared with differentiated NBs. LI was increased in NBs from patients with advanced-stage and high-risk group. Nuclear-PROX1 expression in tumoral cells was present in 35/69 (51%) NBs but was absent in all GNs. PROX1 expression was significantly higher in UD/PD compared with differentiated NBs. It was also higher in NBs with all adverse clinicopathological and biological variables. LI, PROX1 cellular expression and high LD correlated with a shorter overall survival and event-free survival (EFS). Multivariable Cox regression analysis showed that the effect of LD on both OS and EFS was independent of mitosis-karyorrhexis index and MYCN amplification. Increased LD, LI and cellular expression correlated with adverse factors in NBs. Increased LD correlated with LNM suggesting that PROX1 contributes to neuroblastoma progression and lymphatic spread.