The involvement of effector T cells and regulatory T (T reg) cells in opposing and promoting solid organ carcinogenesis, respectively, is viewed as a shifting balance between a breach versus ...establishment of tolerance to tumor or self-antigens. We considered that tumor-associated T cells might promote malignancy via distinct mechanisms used by T cells in nonlymphoid organs to assist in their maintenance upon injury or stress. Recent studies suggest that T reg cells can participate in tissue repair in a manner separable from their immunosuppressive capacity. Using transplantable models of lung tumors in mice, we found that amphiregulin, a member of the epidermal growth factor family, was prominently up-regulated in intratumoral T reg cells. Furthermore, T cell-restricted amphiregulin deficiency resulted in markedly delayed lung tumor progression. This observed deterrence in tumor progression was not associated with detectable changes in T cell immune responsiveness or T reg and effector T cell numbers. These observations suggest a novel "nonimmune" modality for intratumoral T reg and effector T cells in promoting tumor growth through the production of factors normally involved in tissue repair and maintenance.
The immunosuppressive function of regulatory T (T
) cells is dependent on continuous expression of the transcription factor Foxp3. Foxp3 loss of function or induced ablation of T
cells results in a ...fatal autoimmune disease featuring all known types of inflammatory responses with every manifestation stemming from T
cell paucity, highlighting a vital function of T
cells in preventing fatal autoimmune inflammation. However, a major question remains whether T
cells can persist and effectively exert their function in a disease state, where a broad spectrum of inflammatory mediators can either inactivate T
cells or render innate and adaptive pro-inflammatory effector cells insensitive to suppression. By reinstating Foxp3 protein expression and suppressor function in cells expressing a reversible Foxp3 null allele in severely diseased mice, we found that the resulting single pool of rescued T
cells normalized immune activation, quelled severe tissue inflammation, reversed fatal autoimmune disease and provided long-term protection against them. Thus, T
cells are functional in settings of established broad-spectrum systemic inflammation and are capable of affording sustained reset of immune homeostasis.
Metaplastic breast carcinoma is a rare and aggressive histologic type of breast cancer, preferentially displaying a triple-negative phenotype. We sought to define the transcriptomic heterogeneity of ...metaplastic breast cancers on the basis of current gene expression microarray-based classifiers, and to determine whether these tumors display gene copy number profiles consistent with those of BRCA1-associated breast cancers. Twenty-eight consecutive triple-negative metaplastic breast carcinomas were reviewed, and the metaplastic component present in each frozen specimen was defined (ie, spindle cell, squamous, chondroid metaplasia). RNA and DNA extracted from frozen sections with tumor cell content >60% were subjected to gene expression (Illumina HumanHT-12 v4) and copy number profiling (Affymetrix SNP 6.0), respectively. Using the best practice PAM50/claudin-low microarray-based classifier, all metaplastic breast carcinomas with spindle cell metaplasia were of claudin-low subtype, whereas those with squamous or chondroid metaplasia were preferentially of basal-like subtype. Triple-negative breast cancer subtyping using a dedicated website (http://cbc.mc.vanderbilt.edu/tnbc/) revealed that all metaplastic breast carcinomas with chondroid metaplasia were of mesenchymal-like subtype, spindle cell carcinomas preferentially of unstable or mesenchymal stem-like subtype, and those with squamous metaplasia were of multiple subtypes. None of the cases was classified as immunomodulatory or luminal androgen receptor subtype. Integrative clustering, combining gene expression and gene copy number data, revealed that metaplastic breast carcinomas with spindle cell and chondroid metaplasia were preferentially classified as of integrative clusters 4 and 9, respectively, whereas those with squamous metaplasia were classified into six different clusters. Eight of the 26 metaplastic breast cancers subjected to SNP6 analysis were classified as BRCA1-like. The diversity of histologic features of metaplastic breast carcinomas is reflected at the transcriptomic level, and an association between molecular subtypes and histology was observed. BRCA1-like genomic profiles were found only in a subset (31%) of metaplastic breast cancers, and were not associated with a specific molecular or histologic subtype.
The regulatory T cell (T reg cell) T cell receptor (TCR) repertoire is highly diverse and skewed toward recognition of self-antigens. TCR expression by T reg cells is continuously required for ...maintenance of immune tolerance and for a major part of their characteristic gene expression signature; however, it remains unknown to what degree diverse TCR-mediated interactions with cognate self-antigens are required for these processes. In this study, by experimentally switching the T reg cell TCR repertoire to a single T reg cell TCR, we demonstrate that T reg cell function and gene expression can be partially uncoupled from TCR diversity. An induced switch of the T reg cell TCR repertoire to a random repertoire also preserved, albeit to a limited degree, the ability to suppress lymphadenopathy and T helper cell type 2 activation. At the same time, these perturbations of the T reg cell TCR repertoire led to marked immune cell activation, tissue inflammation, and an ultimately severe autoimmunity, indicating the importance of diversity and specificity for optimal T reg cell function.
Recent evidence suggests that lobular carcinoma in situ (LCIS) can be a clonal precursor of invasive breast cancers of both the ductal and lobular phenotypes. We sought to confirm these findings with ...an extensive study of fresh frozen breast specimens from women undergoing mastectomy.
Patients with a history of LCIS presenting for therapeutic mastectomy were identified prospectively. Frozen tissue blocks were collected, screened for lesions of interest, and subjected to microdissection and DNA extraction. Copy number profiling, whole-exome sequencing, or both were performed. Clonal relatedness was assessed using specialized statistical techniques developed for this purpose.
After exclusions for genotyping failure, a total of 84 lesions from 30 patients were evaluated successfully. Strong evidence of clonal relatedness was observed between an LCIS lesion and the invasive cancer for the preponderance of cases with lobular carcinoma. Anatomically distinct in situ lesions of both ductal and lobular histology were also shown to be frequently clonally related.
These data derived from women with LCIS with or without invasive cancer confirm that LCIS is commonly the clonal precursor of invasive lobular carcinoma and that distinct foci of LCIS frequently share a clonal origin, as do foci of LCIS and ductal carcinoma in situ.
ST2, the receptor for the alarmin IL-33, is expressed by a subset of regulatory T (T reg) cells residing in nonlymphoid tissues, and these cells can potently expand upon provision of exogenous IL-33. ...Whether the accumulation and residence of T reg cells in tissues requires their cell-intrinsic expression of and signaling by ST2, or whether indirect IL-33 signaling acting on other cells suffices, has been a matter of contention. Here, we report that ST2 expression on T reg cells is largely dispensable for their accumulation and residence in nonlymphoid organs, including the visceral adipose tissue (VAT), even though cell-intrinsic sensing of IL-33 promotes type 2 cytokine production by VAT-residing T reg cells. In addition, we uncovered a novel ST2-dependent role for T reg cells in limiting the size of IL-17A-producing γδT cells in the CNS in a mouse model of neuroinflammation, experimental autoimmune encephalomyelitis (EAE). Finally, ST2 deficiency limited to T reg cells led to disease exacerbation in EAE.
Intestinal health relies on the immunosuppressive activity of CD4
regulatory T (T
) cells
. Expression of the transcription factor Foxp3 defines this lineage, and can be induced extrathymically by ...dietary or commensal-derived antigens in a process assisted by a Foxp3 enhancer known as conserved non-coding sequence 1 (CNS1)
. Products of microbial fermentation including butyrate facilitate the generation of peripherally induced T
(pT
) cells
, indicating that metabolites shape the composition of the colonic immune cell population. In addition to dietary components, bacteria modify host-derived molecules, generating a number of biologically active substances. This is epitomized by the bacterial transformation of bile acids, which creates a complex pool of steroids
with a range of physiological functions
. Here we screened the major species of deconjugated bile acids for their ability to potentiate the differentiation of pT
cells. We found that the secondary bile acid 3β-hydroxydeoxycholic acid (isoDCA) increased Foxp3 induction by acting on dendritic cells (DCs) to diminish their immunostimulatory properties. Ablating one receptor, the farnesoid X receptor, in DCs enhanced the generation of T
cells and imposed a transcriptional profile similar to that induced by isoDCA, suggesting an interaction between this bile acid and nuclear receptor. To investigate isoDCA in vivo, we took a synthetic biology approach and designed minimal microbial consortia containing engineered Bacteroides strains. IsoDCA-producing consortia increased the number of colonic RORγt-expressing T
cells in a CNS1-dependent manner, suggesting enhanced extrathymic differentiation.
Regulatory T (T reg) cells, a specialized subset of CD4
T cells, are essential to prevent fatal autoimmunity. Expression of the T reg lineage-defining transcription factor Foxp3, and therefore their ...differentiation in the thymus, is dependent upon T cell receptor (TCR) and interleukin-2 (IL-2) signaling. Here, we report that the majority of IL-2-producing cells in the thymus are mature CD4 single-positive (CD4SP) thymocytes and that continuous IL-2 production sustained thymic T reg cell generation and control of systemic immune activation. Furthermore, single-cell RNA sequencing analysis of CD4 thymocyte subsets revealed that IL-2 was expressed in self-reactive CD4SP thymocytes, which also contain T reg precursor cells. Thus, our results suggest that the thymic T reg cell pool size is scaled by a key niche factor, IL-2, produced by self-reactive CD4SP thymocytes. This IL-2-dependent scaling of thymic T reg cell generation by overall self-reactivity of a mature post-selection thymic precursor pool may likely ensure adequate control of autoimmunity.
Adaptive immune responses are tailored to different types of pathogens through differentiation of naive CD4 T cells into functionally distinct subsets of effector T cells (T helper 1 (T
1), T
2, and ...T
17) defined by expression of the key transcription factors T-bet, GATA3, and RORγt, respectively. Regulatory T (T
) cells comprise a distinct anti-inflammatory lineage specified by the X-linked transcription factor Foxp3 (refs 2, 3). Paradoxically, some activated T
cells express the aforementioned effector CD4 T cell transcription factors, which have been suggested to provide T
cells with enhanced suppressive capacity. Whether expression of these factors in T
cells-as in effector T cells-is indicative of heterogeneity of functionally discrete and stable differentiation states, or conversely may be readily reversible, is unknown. Here we demonstrate that expression of the T
1-associated transcription factor T-bet in mouse T
cells, induced at steady state and following infection, gradually becomes highly stable even under non-permissive conditions. Loss of function or elimination of T-bet-expressing T
cells-but not of T-bet expression in T
cells-resulted in severe T
1 autoimmunity. Conversely, following depletion of T-bet
T
cells, the remaining T-bet
cells specifically inhibited T
1 and CD8 T cell activation consistent with their co-localization with T-bet
effector T cells. These results suggest that T-bet
T
cells have an essential immunosuppressive function and indicate that T
cell functional heterogeneity is a critical feature of immunological tolerance.
Regulatory T (Treg) cells expressing the transcription factor Foxp3 are an essential suppressive T cell lineage of dual origin: Foxp3 induction in thymocytes and mature CD4+ T cells gives rise to ...thymic (tTreg) and peripheral (pTreg) Treg cells, respectively. While tTreg cells suppress autoimmunity, pTreg cells enforce tolerance to food and commensal microbiota. However, the role of Foxp3 in pTreg cells and the mechanisms supporting their differentiation remain poorly understood. Here, we used genetic tracing to identify microbiota-induced pTreg cells and found that many of their distinguishing features were Foxp3 independent. Lineage-committed, microbiota-dependent pTreg-like cells persisted in the colon in the absence of Foxp3. While Foxp3 was critical for the suppression of a Th17 cell program, colitis, and mastocytosis, pTreg cells suppressed colonic effector T cell expansion in a Foxp3-independent manner. Thus, Foxp3 and the tolerogenic signals that precede and promote its expression independently confer distinct facets of pTreg functionality.
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•Developed a strategy for genetic labeling of peripherally induced Treg (pTreg) cells•Expression of a pTreg transcriptional program is Foxp3-independent•Foxp3 is dispensable for commitment and fitness of microbiota-dependent pTreg cells•Foxp3-deficient Treg cells can suppress colonic T cell expansion
Foxp3 induction in mature CD4+ T cells gives rise to peripheral Treg (pTreg) cells that enforce tolerance to food and commensal microbes. However, the role of Foxp3 in pTreg cells and the mechanisms supporting their differentiation remain unclear. Van der Veeken et al. use genetic tracing to identify microbiota-induced pTreg cells and find that they have Foxp3-dependent and Foxp3-independent features.
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