Xi K. Zhou

Obesity-dependent changes in interstitial ECM mechanics promote breast tumorigenesis

Obesity leads to fibrotic remodeling of mammary adipose tissue, and the resulting increase in interstitial extracellular matrix stiffness promotes breast tumor malignancy. Fat fibrosis and breast cancer One of the many risk factors for cancer is obesity—but why? Seo et al. examined the cellular, structural, and molecular changes that happen in breast tissue in obese animals and people. They found that obesity induces fibrotic remodeling of the mammary fat pad, leading to changes in extracellular matrix (ECM) mechanical properties, via myofibroblasts and adipose stem cells (ASCs), regardless of ovary function. Through altered mechanotransduction, ECM from obese mice promoted human breast cancer cell growth, as well as the growth of premalignant breast cells (those that have yet to become cancerous). Tissues from obese patients revealed more severe fibrotic remodeling around tumors and higher levels of a key mechanosignaling component, YAP/TAZ, than their lean counterparts. The authors further demonstrated that caloric restriction in obese mice decreased fibrosis in mammary fat, suggesting a therapeutic angle for obesity-related cancers. By linking tumorigenesis to the behavior of fat cells and ECM mechanics, the authors point toward new drug targets for preventing cancer progression. However, a cautionary tale also exists in the use of adipose tissue and cells for patients after mastectomy, as ASCs from obese individuals may have the capacity to promote breast cancer recurrence. Obesity and extracellular matrix (ECM) density are considered independent risk and prognostic factors for breast cancer. Whether they are functionally linked is uncertain. We investigated the hypothesis that obesity enhances local myofibroblast content in mammary adipose tissue and that these stromal changes increase malignant potential by enhancing interstitial ECM stiffness. Indeed, mammary fat of both diet- and genetically induced mouse models of obesity were enriched for myofibroblasts and stiffness-promoting ECM components. These differences were related to varied adipose stromal cell (ASC) characteristics because ASCs isolated from obese mice contained more myofibroblasts and deposited denser and stiffer ECMs relative to ASCs from lean control mice. Accordingly, decellularized matrices from obese ASCs stimulated mechanosignaling and thereby the malignant potential of breast cancer cells. Finally, the clinical relevance and translational potential of our findings were supported by analysis of patient specimens and the observation that caloric restriction in a mouse model reduces myofibroblast content in mammary fat. Collectively, these findings suggest that obesity-induced interstitial fibrosis promotes breast tumorigenesis by altering mammary ECM mechanics with important potential implications for anticancer therapies.

Impact of obesity on the survival of patients with early-stage squamous cell carcinoma of the oral tongue.

Although obesity increases risk and negatively affects survival for many malignancies, the prognostic implications in squamous cell carcinoma (SCC) of the oral tongue, a disease often associated with prediagnosis weight loss, are unknown.

IgA-coated E. coli enriched in Crohn's disease spondyloarthritis promote TH17-dependent inflammation.

IgA-reactive E. coli in Crohn’s disease–associated spondyloarthritis link mucosal immunity and systemic inflammation. Pathosymbiont perturbation of immune homeostasis The influence of the gut microbiome extends beyond the intestines and can modulate many host systems. A subset of Crohn’s disease patients also experience painful spondyloarthritis, and Viladomiu et al. discovered that the immune systems of these patients are more likely to recognize a certain kind of Escherichia coli. As colonization with this bacterium induced systemic TH17 immunity and worsened development of colitis and arthritis in mouse models, this pathosymbiont may be causing a systemic TH17-driven inflammation that leads to extraintestinal complications in Crohn’s disease patients, such as stiffness and spinal pain. Precise targeting of these types of bacteria or reversing the TH17 phenotype they induce could bring relief to patients. Peripheral spondyloarthritis (SpA) is a common extraintestinal manifestation in patients with active inflammatory bowel disease (IBD) characterized by inflammatory enthesitis, dactylitis, or synovitis of nonaxial joints. However, a mechanistic understanding of the link between intestinal inflammation and SpA has yet to emerge. We evaluated and functionally characterized the fecal microbiome of IBD patients with or without peripheral SpA. Coupling the sorting of immunoglobulin A (IgA)–coated microbiota with 16S ribosomal RNA–based analysis (IgA-seq) revealed a selective enrichment in IgA-coated Escherichia coli in patients with Crohn’s disease–associated SpA (CD-SpA) compared to CD alone. E. coli isolates from CD-SpA–derived IgA-coated bacteria were similar in genotype and phenotype to an adherent-invasive E. coli (AIEC) pathotype. In comparison to non-AIEC E. coli, colonization of germ-free mice with CD-SpA E. coli isolates induced T helper 17 cell (TH17) mucosal immunity, which required the virulence-associated metabolic enzyme propanediol dehydratase (pduC). Modeling the increase in mucosal and systemic TH17 immunity we observed in CD-SpA patients, colonization of interleukin-10–deficient or K/BxN mice with CD-SpA–derived E. coli lead to more severe colitis or inflammatory arthritis, respectively. Collectively, these data reveal the power of IgA-seq to identify immunoreactive resident pathosymbionts that link mucosal and systemic TH17-dependent inflammation and offer microbial and immunophenotype stratification of CD-SpA that may guide medical and biologic therapy.

Norepinephrine and Adenosine-5’-triphosphate Synergize in Inducing IL-6 Production by Human Dermal Microvascular Endothelial Cells

Endothelial cells (ECs) play important roles in cutaneous inflammation, in part, by release of inflammatory chemokines/cytokines. Because dermal blood vessels are innervated by sympathetic nerves, the sympathetic neurotransmitter norepinephrine (NE) and the co-transmitter adenosine-5-triphosphate (ATP) may regulate expression of EC inflammatory factors. We focused on IL-6 regulation because it has many inflammatory and immune functions, including participation in Th17 cell differentiation. Strikingly, NE and ATP synergistically induced release of IL-6 by a human dermal microvascular endothelial cell line (HMEC-1). Adrenergic antagonist and agonist studies indicated that the effect of NE on induced IL-6 release is primarily mediated by β2-adrenergic receptors (ARs). By real-time PCR IL-6 mRNA was also synergistically induced in HMEC-1 cells. This synergistic effect of NE and ATP was reproduced in primary human dermal endothelial cells (pHDMECs) and is also primarily mediated by β2-ARs. Under conditions of stress, activation of the symphathetic nervous system may lead to release of ATP and NE by sympathetic nerves surrounding dermal blood vessels with induction of IL-6 production by ECs. IL-6 may then participate in immune and inflammatory processes including generation of Th17 cells. Production of IL-6 in this manner might explain stress-induced exacerbation of psoriasis, and perhaps, other skin disorders involving Th17-type immunity.

Pituitary adenylate cyclase‐activating peptide and vasoactive intestinal polypeptide bias Langerhans cell Ag presentation toward Th17 cells

Epidermal Langerhans cells (LCs) are dendritic APCs that play an important role in cutaneous immune responses. LCs are associated with epidermal nerves and the neuropeptides vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase‐activating polypeptide (PACAP) inhibit LC Ag presentation for Th1‐type immune responses. Here, we examined whether PACAP or VIP modulates LC Ag presentation for induction of IL‐17A‐producing CD4+ T cells. Treatment with VIP or PACAP prior to in vitro LC Ag presentation to CD4+ T cells enhanced IL‐17A, IL‐6, and IL‐4 production, decreased interferon (IFN)‐γ and interleukin (IL)‐22 release, and increased RORγt and Gata3 mRNA expression while decreasing T‐bet expression. The CD4+ T‐cell population was increased in IL‐17A‐ and IL‐4‐expressing cells and decreased in IFN‐γ‐expressing cells. Addition of anti‐IL‐6 mAb blocked the enhanced IL‐17A production seen with LC preexposure to VIP or PACAP. Intradermal administration of VIP or PACAP prior to application of a contact sensitizer at the injection site, followed by harvesting of draining lymph node CD4+ T cells and stimulation with anti‐CD3/anti‐CD28 mAbs, enhanced IL‐17A and IL‐4 production but reduced production of IL‐22 and IFN‐γ. PACAP and VIP are endogenous mediators that likely regulate immunity and immune‐mediated diseases within the skin.

White adipose tissue inflammation and cancer‐specific survival in patients with squamous cell carcinoma of the oral tongue

Obesity is associated with increased adipose tissue in the tongue. Chronic white adipose tissue (WAT) inflammation commonly occurs in the obese. We investigated whether WAT inflammation in the tongue impacts survival in patients with squamous cell carcinoma (SCC) of the oral tongue.

Genetic Deletion of Microsomal Prostaglandin E Synthase-1 Suppresses Mouse Mammary Tumor Growth and Angiogenesis

The cyclooxygenase/prostaglandin (COX/PG) signaling pathway is of central importance in inflammation and neoplasia. COX inhibitors are widely used for analgesia and also have demonstrated activity for cancer prophylaxis. However, cardiovascular toxicity associated with this drug class diminishes their clinical utility and motivates the development of safer approaches both for pain relief and cancer prevention. The terminal synthase microsomal PGE synthase-1 (mPGES-1) has attracted considerable attention as a potential target. Overexpression of mPGES-1 has been observed in both colorectal and breast cancers, and gene knockout and overexpression approaches have established a role for mPGES-1 in gastrointestinal carcinogenesis. Here we evaluate the contribution of mPGES-1 to mammary tumorigenesis using a gene knockout approach. Mice deficient in mPGES-1 were crossed with a strain in which breast cancer is driven by overexpression of human epidermal growth factor receptor 2 (HER2/neu). Loss of mPGES-1 was associated with a substantial reduction in intramammary PGE2 levels, aromatase activity, and angiogenesis in mammary glands from HER2/neu transgenic mice. Consistent with these findings, we observed a significant reduction in multiplicity of tumors ≥1mm in diameter, suggesting that mPGES-1 contributes to mammary tumor growth. Our data identify mPGES-1 as a potential anti-breast cancer target.

Calcitonin Gene–Related Peptide–Exposed Endothelial Cells Bias Antigen Presentation to CD4+ T Cells toward a Th17 Response

Calcitonin gene–related peptide (CGRP) is a neuropeptide with well-established immunomodulatory functions. CGRP-containing nerves innervate dermal blood vessels and lymph nodes. We examined whether CGRP regulates the outcome of Ag presentation by Langerhans cells (LCs) to T cells through actions on microvascular endothelial cells (ECs). Exposure of primary murine dermal microvascular ECs (pDMECs) to CGRP followed by coculture with LCs, responsive CD4+ T cells and Ag resulted in increased production of IL-6 and IL-17A accompanied by inhibition of IFN-γ, IL-4, and IL-22 compared with wells containing pDMECs treated with medium alone. Physical contact between ECs and LCs or T cells was not required for this effect and, except for IL-4, we demonstrated that IL-6 production by CGRP-treated pDMECs was involved in these effects. CD4+ cells expressing cytoplasmic IL-17A were increased, whereas cells expressing cytoplasmic IFN-γ or IL-4 were decreased by the presence of CGRP-treated pDMECs. In addition, the level of retinoic acid receptor–related orphan receptor γt mRNA was significantly increased, whereas T-bet and GATA3 expression was inhibited. Immunization at the site of intradermally administered CGRP led to a similar bias in CD4+ T cells from draining lymph node cells toward IL-17A and away from IFN-γ. Actions of nerve-derived CGRP on ECs may have important regulatory effects on the outcome of Ag presentation with consequences for the expression of inflammatory skin disorders involving Th17 cells.

N-acetyl-S-farnesyl-l-cysteine suppresses chemokine production by human dermal microvascular endothelial cells.

Isoprenylcysteine (IPC) molecules modulate G‐protein‐coupled receptor signalling. The archetype of this class is N‐acetyl‐S‐farnesyl‐l‐cysteine (AFC). Topical application of AFC locally inhibits skin inflammation and elicitation of contact hypersensitivity in vivo. However, the mechanism of these anti‐inflammatory effects is not well understood. Dermal microvascular endothelial cells (ECs) are involved in inflammation, in part, by secreting cytokines that recruit inflammatory cells. We have previously shown that the sympathetic nerve cotransmitter adenosine‐5′‐triphosphate (ATP) and adenosine‐5′‐O‐(3‐thio) triphosphate (ATPγS), an ATP analogue that is resistant to hydrolysis, increase secretion of the chemokines CXCL8 (interleukin‐8), CCL2 (monocyte chemotactic protein‐1) and CXCL1 (growth‐regulated oncogene α) by dermal microvascular ECs. Production of these chemokines can also be induced by the exposure to the proinflammatory cytokine TNFα. We have now demonstrated that AFC dose‐dependently inhibits ATP‐, ATPγS‐ and TNFα‐induced production of CXCL1, CXCL8 and CCL2 by a human dermal microvascular EC line (HMEC‐1) in vitro under conditions that do not affect cell viability. Inhibition of ATPγS‐ or TNFα‐stimulated release of these chemokines was associated with reduced mRNA levels. N‐acetyl‐S‐geranyl‐l‐cysteine, an IPC analogue that is inactive in inhibiting G‐protein‐coupled signalling, had greatly reduced ability to suppress stimulated chemokine production. AFC may exert its anti‐inflammatory effects through the inhibition of chemokine production by stimulated ECs.

Regulation of T helper cell responses during antigen presentation by norepinephrine-exposed endothelial cells

Dermal blood vessels and regional lymph nodes are innervated by sympathetic nerves and, under stress, sympathetic nerves release norepinephrine (NE). Exposure of primary murine dermal microvascular endothelial cells (pDMECs) to NE followed by co‐culture with Langerhans cells (LCs), responsive CD4+ T‐cells and antigen resulted in modulation of CD4+ T‐cell responses. NE‐treatment of pDMECs induced increased production of interleukin (IL)‐6 and IL‐17A while down‐regulating interferon (IFN)‐γ and IL‐22 release. This effect did not require contact between pDMECs and LCs or T‐cells and depended upon pDMEC production of IL‐6. The presence of NE‐treated pDMECs increased the proportion of CD4+ T‐cells expressing intracellular IL‐17A and increased IL‐17A mRNA while decreasing the proportion of IFN‐γ‐ or IL‐22‐expressing CD4+ T‐cells and mRNA levels for those cytokines. Retinoic acid receptor‐related orphan receptor gamma (ROR‐γt) mRNA was significantly increased in CD4+ T‐cells while T‐box transcription factor (T‐bet) mRNA was decreased. Intradermal administration of NE prior to hapten immunization at the injection site produced a similar bias in draining lymph node CD4+ T‐cells towards IL‐17A and away from IFN‐γ and IL‐22 production. Under stress, release of NE may have significant regulatory effects on the outcome of antigen presentation through actions on ECs with enhancement of inflammatory skin disorders involving IL‐17/T helper type 17 (Th17) cells.