Epidermal growth factor receptor (EGFR) signaling is a key mediator of hormone-induced leukocyte infiltration in the pubertal female mammary gland

Combined effect of pantoprazole and mesenchymal stem cells on experimentally induced gastric ulcer: implication of oxidative stress, inflammation and apoptosis pathways

Gastric ulcer (GU) is one of the most common diseases of the upper gastrointestinal tract that affects millions of people worldwide. This study aimed to investigate the possible alleviating effect of a combined treatment of pantoprazole (PANTO) and adipose tissue-derived mesenchymal stem cells (ADSCs) in comparison with each treatment alone on the healing process of the experimentally induced GU in rats, and to uncover the involved pathways. Rats were divided into five groups: (1) Control, (2) GU, (3) PANTO, (4) ADSCs and (5) ADSCs + PANTO. Markers of oxidative stress, inflammation and apoptosis were assessed. The current data indicated that PANTO-, ADSCs- and ADSCs + PANTO-treated groups showed significant drop (p < 0.05) in serum advanced oxidation protein products (AOPPs) and advanced glycation end products (AGEPs) along with significant elevation (p < 0.05) in serum TAC versus the untreated GU group. Moreover, the treated groups (PANTO, ADSCs and ADSCs + PANTO) displayed significant down-regulation (p < 0.05) in gastric nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), tumor necrosis factor alpha (TNF-α), cyclooxygenase-2 (COX-2), intercellular adhesion molecule-1 (ICAM-1), matrix metallopeptidase 9 (MMP-9) and caspase-3 along with significant up-regulation (p < 0.05) in vascular endothelial growth factor (VEGF) and peroxisome proliferator-activated receptor gamma (PPARγ) genes expression compared to the untreated GU group. Immunohistochemical examination of gastric tissue for transforming growth factor β1 (TGF-β1), epidermal growth factor (EGF) and proliferating cell nuclear antigen (PCNA) showed moderate to mild and weak immune reactions, respectively in the PANTO-, ADSCs- and ADSCs + PANTO-treated rat. Histopathological investigation of gastric tissue revealed moderate to slight histopathological alterations and almost normal histological features of the epithelial cells, gastric mucosal layer, muscularis mucosa and submucosa in PANTO-, ADSCs- and ADSCs + PANTO-treated rats, respectively. Conclusively, the co-treatment with ADSCs and PANTO evidenced sententious physiological protection against GU by suppressing oxidative stress, inhibiting inflammation and reducing apoptosis with consequent acceleration of gastric tissue healing process.

Toward Characterizing Lymphatic Vasculature in the Mammary Gland During Normal Development and Tumor-Associated Remodeling

Lymphatic vasculature has been shown to promote metastatic spread of breast cancer. Lymphatic vasculature, which is made up of larger collecting vessels and smaller capillaries, has specialized cell junctions that facilitate cell intravasation. Normally, these junctions are designed to collect immune cells and other cellular components for immune surveillance by lymph nodes, but they are also utilized by cancer cells to facilitate metastasis. Although lymphatic development overall in the body has been well-characterized, there has been little focus on how the lymphatic network changes in the mammary gland during stages of remodeling such as pregnancy, lactation, and postpartum involution. In this review, we aim to define the currently known lymphangiogenic factors and lymphatic remodeling events during mammary gland morphogenesis. Furthermore, we juxtapose mammary gland pubertal development and postpartum involution to show similarities of pro-lymphangiogenic signaling as well as other molecular signals for epithelial cell survival that are critical in these morphogenic stages. The similar mechanisms include involvement of M2-polarized macrophages that contribute to matrix remodeling and vasculogenesis; signal transducer and activator of transcription (STAT) survival and proliferation signaling; and cyclooxygenase 2 (COX2)/Prostaglandin E2 (PGE2) signaling to promote ductal and lymphatic expansion. Investigation and characterization of lymphangiogenesis in the normal mammary gland can provide insight to targetable mechanisms for lymphangiogenesis and lymphatic spread of tumor cells in breast cancer.

Cancer invasion and metastasis: Insights from murine pubertal mammary gland morphogenesis

Cancer invasion and metastasis accounts for the majority of cancer related mortality. A better understanding of the players that drive the aberrant invasion and migration of tumors cells will provide critical targets to inhibit metastasis. Postnatal pubertal mammary gland morphogenesis is characterized by highly proliferative, invasive, and migratory normal epithelial cells. Identifying the molecular regulators of pubertal gland development is a promising strategy since tumorigenesis and metastasis is postulated to be a consequence of aberrant reactivation of developmental stages. In this review, we summarize the pubertal morphogenesis regulators that are involved in cancer metastasis and revisit pubertal mammary gland transcriptome profiling to uncover both known and unknown metastasis genes. Our updated list of pubertal morphogenesis regulators shows that most are implicated in invasion and metastasis. This review highlights molecular linkages between development and metastasis and provides a guide for exploring novel metastatic drivers.

ERBB Receptors and Their Ligands in the Developing Mammary Glands of Different Species: Fifteen Characters in Search of an Author

The ERBB tyrosine kinase receptors and their ligands belong to a complex family that has diverse biological effects and expression profiles in the developing mammary glands, where its members play an essential role in translating hormone signals into local effects. While our understanding of these processes stems mostly from mouse models, there is the potential for differences in how this family functions in the mammary glands of other species, particularly in light of their unique histomorphological features. Herein we review the postnatal distribution and function of ERBB receptors and their ligands in the mammary glands of rodents and humans, as well as for livestock and companion animals. Our analysis highlights the diverse biology for this family and its members across species, the regulation of their expression, and how their roles and functions might be modulated by varying stromal composition and hormone interactions. Given that ERBB receptors and their ligands have the potential to influence processes ranging from normal mammary development to diseased states such as cancer and/or mastitis, both in human and veterinary medicine, a more complete understanding of their biological functions should help to direct future research and the identification of new therapeutic targets.

Epidermal Growth Factor Receptor in Hepatic Endothelial Cells Suppresses MCP-1-Dependent Monocyte Recruitment in Diabetes

Insulin resistance is a compromised response to insulin in target tissues such as liver. Emerging evidence shows that vascular endothelial cells (ECs) are critical in mediating glucose metabolism. However, how liver ECs can regulate inflammation in the setting of insulin resistance is still unknown. Using genome-wide transcriptome analysis of ECs isolated from diabetic mice, we found enrichment of the genes involved in epidermal growth factor receptor (Egfr) signaling. In line with this, hepatic sinusoidal ECs in diabetic mice had elevated levels of Egfr expression. Interestingly, we found an increased number of hepatic myeloid cells, especially macrophages, and systemic glucose intolerance in Cdh5Cre/+Egfrfl/fl mice lacking Egfr in ECs compared with littermate control mice with type II diabetes. Egfr deficiency upregulated the expression of MCP-1 in hepatic sinusoidal ECs. This resulted in augmented monocyte recruitment and macrophage differentiation in Cdh5Cre/+Egfrfl/fl mice compared with littermate control mice as determined by a mouse model of parabiosis. Finally, MCP-1 neutralization and hepatic macrophage depletion in Cdh5Cre/+Egfrfl/fl mice resulted in a reduced number of hepatic macrophages and ameliorated glucose intolerance compared with the control groups. Collectively, these results demonstrate a protective endothelial Egfr signaling in reducing monocyte-mediated hepatic inflammation and glucose intolerance in type II diabetic mice.

Roles of Macrophages in Advanced Liver Fibrosis, Identified Using a Newly Established Mouse Model of Diet-Induced Non-Alcoholic Steatohepatitis

Macrophages play critical roles in the pathogenesis of non-alcoholic steatohepatitis (NASH). However, it is unclear which macrophage subsets are critically involved in the development of inflammation and fibrosis in NASH. In TSNO mice fed a high-fat/cholesterol/cholate-based diet, which exhibit advanced liver fibrosis that mimics human NASH, we found that Kupffer cells (KCs) were less abundant and recruited macrophages were more abundant, forming hepatic crown-like structures (hCLS) in the liver. The recruited macrophages comprised two subsets: CD11c+/Ly6C- and CD11c-/Ly6C+ cells. CD11c+ cells were present in a mesh-like pattern around the lipid droplets, constituting the hCLS. In addition, CD11c+ cells colocalized with collagen fibers, suggesting that this subset of recruited macrophages might promote advanced liver fibrosis. In contrast, Ly6C+ cells were present in doughnut-like inflammatory lesions, with a lipid droplet in the center. Finally, RNA sequence analysis indicates that CD11c+/Ly6C- cells promote liver fibrosis and hepatic stellate cell (HSC) activation, whereas CD11c-/Ly6C+ cells are a macrophage subset that play an anti-inflammatory role and promote tissue repair in NASH. Taken together, our data revealed changes in liver macrophage subsets during the development of NASH and shed light on the roles of the recruited macrophages in the pathogenesis of advanced fibrosis in NASH.

EGFR-mediated activation of adipose tissue macrophages promotes obesity and insulin resistance

Obesity and obesity-related health complications are increasing in prevalence. Adipose tissue from obese subjects has low-grade, chronic inflammation, leading to insulin resistance. Adipose tissue macrophages (ATMs) are a source of proinflammatory cytokines that further aggravate adipocyte dysfunction. In response to a high fat diet (HFD), ATM numbers initially increase by proliferation of resident macrophages, but subsequent increases also result from infiltration in response to chemotactic signals from inflamed adipose tissue. To elucidate the underlying mechanisms regulating the increases in ATMs and their proinflammatory phenotype, we investigated the role of activation of ATM epidermal growth factor receptor (EGFR). A high fat diet increased expression of EGFR and its ligand amphiregulin in ATMs. Selective deletion of EGFR in ATMs inhibited both resident ATM proliferation and monocyte infiltration into adipose tissue and decreased obesity and development of insulin resistance. Therefore, ATM EGFR activation plays an important role in adipose tissue dysfunction.

The Mammary Gland: Basic Structure and Molecular Signaling during Development

The mammary gland is a compound, branched tubuloalveolar structure and a major characteristic of mammals. The mammary gland has evolved from epidermal apocrine glands, the skin glands as an accessory reproductive organ to support postnatal survival of offspring by producing milk as a source of nutrition. The mammary gland development begins during embryogenesis as a rudimentary structure that grows into an elementary branched ductal tree and is embedded in one end of a larger mammary fat pad at birth. At the onset of ovarian function at puberty, the rudimentary ductal system undergoes dramatic morphogenetic change with ductal elongation and branching. During pregnancy, the alveolar differentiation and tertiary branching are completed, and during lactation, the mature milk-producing glands eventually develop. The early stages of mammary development are hormonal independent, whereas during puberty and pregnancy, mammary gland development is hormonal dependent. We highlight the current understanding of molecular regulators involved during different stages of mammary gland development.

Emerging Evidence for Pleiotropism of Eosinophils

Eosinophils are complex granulocytes with the capacity to react upon diverse stimuli due to their numerous and variable surface receptors, which allows them to respond in very different manners. Traditionally believed to be only part of parasitic and allergic/asthmatic immune responses, as scientific studies arise, the paradigm about these cells is continuously changing, adding layers of complexity to their roles in homeostasis and disease. Developing principally in the bone marrow by the action of IL-5 and granulocyte macrophage colony-stimulating factor GM-CSF, eosinophils migrate from the blood to very different organs, performing multiple functions in tissue homeostasis as in the gastrointestinal tract, thymus, uterus, mammary glands, liver, and skeletal muscle. In organs such as the lungs and gastrointestinal tract, eosinophils are able to act as immune regulatory cells and also to perform direct actions against parasites, and bacteria, where novel mechanisms of immune defense as extracellular DNA traps are key factors. Besides, eosinophils, are of importance in an effective response against viral pathogens by their nuclease enzymatic activity and have been lately described as involved in severe acute respiratory syndrome coronavirus SARS-CoV-2 immunity. The pleiotropic role of eosinophils is sustained because eosinophils can be also detrimental to human physiology, for example, in diseases like allergies, asthma, and eosinophilic esophagitis, where exosomes can be significant pathophysiologic units. These eosinophilic pathologies, require specific treatments by eosinophils control, such as new monoclonal antibodies like mepolizumab, reslizumab, and benralizumab. In this review, we describe the roles of eosinophils as effectors and regulatory cells and their involvement in pathological disorders and treatment.

Eosinophils as Major Player in Type 2 Inflammation: Autoimmunity and Beyond

Eosinophils are a subset of differentiated granulocytes which circulate in peripheral blood and home in several body tissues. Along with their traditional relevance in helminth immunity and allergy, eosinophils have been progressively attributed important roles in a number of homeostatic and pathologic situations. This review aims at summarizing available evidence about eosinophils functions in homeostasis, infections, allergic and autoimmune disorders, and solid and hematological cancers.Their structural and biological features have been described, along with their physiological behavior. This includes their chemokines, cytokines, granular contents, and extracellular traps. Besides, pathogenic- and eosinophilic-mediated disorders have also been addressed, with the aim of highlighting their role in Th2-driven inflammation. In allergy, eosinophils are implicated in the pathogenesis of atopic dermatitis, allergic rhinitis, and asthma. They are also fundamentally involved in autoimmune disorders such as eosinophilic esophagitis, eosinophilic gastroenteritis, acute and chronic eosinophilic pneumonia, and eosinophilic granulomatosis with polyangiitis. In infections, eosinophils are involved in protection not only from parasites but also from fungi, viruses, and bacteria. In solid cancers, local eosinophilic infiltration is variably associated with an improved or worsened prognosis, depending on the histotype. In hematologic neoplasms, eosinophilia can be the consequence of a dysregulated cytokine production or the result of mutations affecting the myeloid lineage.Recent experimental evidence was thoroughly reviewed, with findings which elicit a complex role for eosinophils, in a tight balance between host defense and tissue damage. Eventually, emerging evidence about eosinophils in COVID-19 infection was also discussed.

Common Childhood Viruses and Pubertal Timing: The LEGACY Girls Study

Earlier pubertal development is only partially explained by childhood body mass index; the role of other factors, such as childhood infections, is less understood. Using data from the LEGACY Girls Study (North America, 2011-2016), we prospectively examined the associations between childhood viral infections (cytomegalovirus (CMV), Epstein-Barr virus (EBV), herpes simplex virus (HSV) 1, HSV2) and pubertal timing. We measured exposures based on seropositivity in premenarcheal girls (n = 490). Breast and pubic hair development were classified based on mother-reported Tanner Stage (TS) (TS2+ compared with TS1), adjusting for age, body mass index, and sociodemographic factors. The average age at first blood draw was 9.8 years (standard deviation, 1.9 years). The prevalences were 31% CMV+, 37% EBV+, 14% HSV1+, 0.4% HSV2+, and 16% for both CMV+/EBV+ coinfection. CMV+ infection without coinfection was associated with developing breasts an average of 7 months earlier (hazard ratio (HR) = 2.12, 95% confidence interval (CI): 1.32, 3.40). CMV infection without coinfection and HSV1 and/or HSV2 infection were associated with developing pubic hair 9 months later (HR = 0.41, 95% CI: 0.24, 0.71, and HR = 0.42, 95% CI: 0.22, 0.81, respectively). Infection was not associated with menarche. If replicated in larger cohorts with blood collection prior to any breast development, this study supports the hypothesis that childhood infections might play a role in altering pubertal timing.

The multiple functions and subpopulations of eosinophils in tissues under steady-state and pathological conditions

Eosinophils not only play a critical role in the pathogenesis of eosinophil-associated diseases, but they also have multiple important biological functions, including the maintenance of homeostasis, host defense against infections, immune regulation through canonical Th1/Th2 balance modulation, and anti-inflammatory and anti-tumorigenic activities. Recent studies have elucidated some emerging roles of eosinophils in steady-state conditions; for example, eosinophils contribute to adipose tissue metabolism and metabolic health through alternatively activated macrophages and the maintenance of plasma cells in intestinal tissue and bone marrow. Moreover, eosinophils exert tissue damage through eosinophil-derived cytotoxic mediators that are involved in eosinophilic airway inflammation, leading to diseases including asthma and chronic rhinosinusitis with nasal polyps characterized by fibrin deposition through excessive response by eosinophils-induced. Thus, eosinophils possessing these various effects reflect the heterogenous features of these cells, which suggests the existence of distinct different subpopulations of eosinophils between steady-state and pathological conditions. Indeed, a recent study demonstrated that instead of dividing eosinophils by classical morphological changes into normodense and hypodense eosinophils, murine eosinophils from lung tissue can be phenotypically divided into two distinct subtypes: resident eosinophils and inducible eosinophils gated by Siglec-F^int CD62L⁺ CD101^low and Siglec-F^high CD62L^- CD101^high, respectively. However, it is difficult to explain every function of eosinophils by rEos and iEos, and the relationship between the functions and subpopulations of eosinophils remains controversial. Here, we overview the multiple roles of eosinophils in the tissue and their biological behavior in steady-state and pathological conditions. We also discuss eosinophil subpopulations.

Benzophenone-3 promotion of mammary tumorigenesis is diet-dependent

Benzophenone-3 is a putative endocrine disrupting chemical and common ingredient in sunscreens. The potential of endocrine disrupting chemicals to act as agonists or antagonists in critical hormonally regulated processes, such as mammary gland development and mammary tumorigenesis, demands evaluation of its potential in promoting breast cancer. This study identifies the effects of BP-3 on mammary tumorigenesis with high-fat diet during puberty versus adulthood in Trp53-null transplant BALB/c mice. Benzophenone-3 exposure yielded levels in urine similar to humans subjected to heavy topical sunscreen exposure. Benzophenone-3 was protective for epithelial tumorigenesis in mice fed lifelong low-fat diet, while promotional for epithelial tumorigenesis in mice fed adult high-fat diet. Benzophenone-3 increased tumor cell proliferation, decreased tumor cell apoptosis, and increased tumor vascularity dependent on specific dietary regimen and tumor histopathology. Even in instances of an ostensibly protective effect, other parameters suggest greater risk. Although benzophenone-3 seemed protective on low-fat diet, spindle cell tumors arising in these mice showed increased proliferation and decreased apoptosis. This points to a need for further studies of benzophenone-3 in both animal models and humans as a potential breast cancer risk factor, as well as a more general need to evaluate endocrine disrupting chemicals in varying dietary contexts.

The emerging roles of eosinophils in mucosal homeostasis

Eosinophils are granulocytes, typically implicated as end-stage effector cells in type-II immune responses. They are capable of producing a wide array of pre-formed molecules which render them with vast potential to influence a wide variety of processes. Nonetheless, eosinophil research has traditionally focused on their role in anti-helminthic responses and pathophysiological processes in type-II immune disorders, such as allergy and asthma, where eosinophilia is a hallmark phenotype. However, a number of key studies over the past decade have placed this restricted view of eosinophil function into question, presenting additional evidence for eosinophils as critical regulators of various homeostatic processes including immune maintenance, organ development, and tissue regeneration.

Single-cell RNA-sequencing analysis of estrogen- and endocrine-disrupting chemical-induced reorganization of mouse mammary gland

Menopause is a critical window of susceptibility for its sensitivity to endocrine disrupting chemicals due to the decline of endogenous estrogen. Using a surgical menopausal (ovariectomized) mouse model, we assessed how mammary tissue was affected by both 17β-estradiol (E2) and polybrominated diphenyl ethers (PBDEs). As flame retardants in household products, PBDEs are widely detected in human serum. During physiologically-relevant exposure to E2, PBDEs enhanced E2-mediated regrowth of mammary glands with terminal end bud-like structures. Analysis of mammary gland RNA revealed that PBDEs both augmented E2-facilitated gene expression and modulated immune regulation. Through single-cell RNA sequencing (scRNAseq) analysis, E2 was found to induce Pgr expression in both Esr1+ and Esr1- luminal epithelial cells and Ccl2 expression in Esr1+ fibroblasts. PBDEs promote the E2-AREG-EGFR-M2 macrophage pathway. Our findings support that E2 + PBDE increases the risk of developing breast cancer through the expansion of estrogen-responsive luminal epithelial cells and immune modulation.

Functions of tissue-resident eosinophils

Eosinophils are a prominent cell type in particular host responses such as the response to helminth infection and allergic disease. Their effector functions have been attributed to their capacity to release cationic proteins stored in cytoplasmic granules by degranulation. However, eosinophils are now being recognized for more varied functions in previously underappreciated diverse tissue sites, based on the ability of eosinophils to release cytokines (often preformed) that mediate a broad range of activities into the local environment. In this Review, we consider evolving insights into the tissue distribution of eosinophils and their functional immunobiology, which enable eosinophils to secrete in a selective manner cytokines and other mediators that have diverse, 'non-effector' functions in health and disease.

Amphiregulin as a Novel Serum Marker of Puberty in Girls

STUDY OBJECTIVE

Amphiregulin is a member of the epidermal growth factor family. In breast tissue, amphiregulin is a mediator of estrogen and progesterone signaling. The objectives were to examine the relationship of amphiregulin levels during peripuberty with estrogen levels. DESIGN, SETTING, PARTICIPANTS, INTERVENTIONS, AND MAIN OUTCOME MEASURES: The participants in this analysis were a subset from a longitudinal study of pubertal maturation, the Breast Cancer and the Environment Research Program. They were recruited between ages 3 and 7 years. Blood specimens were selected for hormone analysis between 24 months before and 6 months after breast development. Serum amphiregulin levels were analyzed using enzyme-linked immunosorbent assay.

RESULTS

Amphiregulin levels were measured in 188 girls; 8.5% had a maternal history of breast cancer, and 30.9% of samples were below the limit of detection. Amphiregulin levels were greatest at 18 months before the onset of breast development (P < .006), and the rise in estrone levels between -24 and -18 months was correlated with the increase in amphiregulin levels in the same time period (P = .0002). After adjustment for time relative to breast development, amphiregulin levels were associated with maternal breast cancer (P = .024). Tracking of amphiregulin levels was highly significant (P < .0001) within a given individual.

CONCLUSION

Amphiregulin levels peaked at 18 months before the onset of breast development, were temporally related to the rise in serum estrone, and were significantly associated with maternal history of breast cancer. Elevated amphiregulin levels at puberty might be a predictor of increased breast cancer risk.

The Terminal End Bud: the Little Engine that Could

The mammary gland is one of the most regenerative organs in the body, with the majority of development occurring postnatally and in the adult mammal. Formation of the ductal tree is orchestrated by a specialized structure called the terminal end bud (TEB). The TEB is responsible for the production of mature cell types leading to the elongation of the subtending duct. The TEB is also the regulatory control point for basement membrane deposition, branching, angiogenesis, and pattern formation. While the hormonal control of TEB growth is well characterized, the local regulatory factors are less well understood. Recent studies of pubertal outgrowth and ductal elongation have yielded surprising details in regards to ongoing processes in the TEB. Here we summarize the current understanding of TEB biology, discuss areas of future study, and discuss the use of the TEB as a model for the study of breast cancer.

Estrogen reprograms the activity of neutrophils to foster protumoral microenvironment during mammary involution

Epidemiological studies have indicated increased risk for breast cancer within 10 years of childbirth. Acute inflammation during mammary involution has been suggested to promote this parity-associated breast cancer. We report here that estrogen exacerbates mammary inflammation during involution. Microarray analysis shows that estrogen induces an extensive proinflammatory gene signature in the involuting mammary tissue. This is associated with estrogen-induced neutrophil infiltration. Furthermore, estrogen induces the expression of protumoral cytokines/chemokines, COX-2 and tissue-remodeling enzymes in isolated mammary neutrophils and systemic neutrophil depletion abolished estrogen-induced expression of these genes in mammary tissue. More interestingly, neutrophil depletion diminished estrogen-induced growth of ERα-negative mammary tumor 4T1 in Balb/c mice. These findings highlight a novel aspect of estrogen action that reprograms the activity of neutrophils to create a pro-tumoral microenvironment during mammary involution. This effect on the microenvironment would conceivably aggravate its known neoplastic effect on mammary epithelial cells.

Role of Prolactin in Promotion of Immune Cell Migration into the Mammary Gland

Immune cells in the mammary gland play a number of important roles, including protection against infection during lactation and, after passing into milk, modulation of offspring immunity. However, little is known about the mechanism of recruitment of immune cells to the lactating gland in the absence of infection. Given the importance of prolactin to other aspects of lactation, we hypothesized it would also play a role in immune cell recruitment. Prolactin treatment of adult female mice for a period equivalent to pregnancy and the first week of lactation increased immune cell flux through the mammary gland, as reflected in the number of immune cells in mammary gland-draining, but not other lymph nodes. Conditioned medium from luminal mammary epithelial HC11 cell cultures was chemo-attractive to CD4+ and CD8+ T cells, CD4+ and CD8+ memory T cells, B cells, macrophages, monocytes, eosinophils, and neutrophils. Prolactin did not act as a direct chemo-attractant, but through effects on luminal mammary epithelial cells, increased the chemo-attractant properties of conditioned medium. Macrophages and neutrophils constitute the largest proportion of cells in milk from healthy glands. Depletion of CCL2 and CXCL1 from conditioned medium reduced chemo-attraction of monocytes and neutrophils, and prolactin increased expression of these two chemokines in mammary epithelial cells. We conclude that prolactin is an important player in the recruitment of immune cells to the mammary gland both through its activities to increase epithelial cell number as well as production of chemo-attractants on a per cell basis.

Expression and Function of the Epidermal Growth Factor Receptor in Physiology and Disease

The epidermal growth factor receptor (EGFR) is the prototypical member of a family of membrane-associated intrinsic tyrosine kinase receptors, the ErbB family. EGFR is activated by multiple ligands, including EGF, transforming growth factor (TGF)-α, HB-EGF, betacellulin, amphiregulin, epiregulin, and epigen. EGFR is expressed in multiple organs and plays important roles in proliferation, survival, and differentiation in both development and normal physiology, as well as in pathophysiological conditions. In addition, EGFR transactivation underlies some important biologic consequences in response to many G protein-coupled receptor (GPCR) agonists. Aberrant EGFR activation is a significant factor in development and progression of multiple cancers, which has led to development of mechanism-based therapies with specific receptor antibodies and tyrosine kinase inhibitors. This review highlights the current knowledge about mechanisms and roles of EGFR in physiology and disease.

MicroRNA expression profiles differentiate chronic pain condition subtypes

Chronic pain is a significant health care problem, ineffectively treated because of its unclear etiology and heterogeneous clinical presentation. Emerging evidence demonstrates that microRNAs (miRNAs) regulate the expression of pain-relevant genes, yet little is known about their role in chronic pain. Here, we evaluate the relationship among pain, psychological characteristics, plasma cytokines, and whole blood miRNAs in 22 healthy controls (HCs); 33 subjects with chronic pelvic pain (vestibulodynia, VBD); and 23 subjects with VBD and irritable bowel syndrome (VBD + IBS). VBD subjects were similar to HCs in self-reported pain, psychological profiles, and remote bodily pain. VBD + IBS subjects reported decreased health and function; and an increase in headaches, somatization, and remote bodily pain. Furthermore, VBD subjects exhibited a balance in proinflammatory and anti-inflammatory cytokines, whereas VBD + IBS subjects failed to exhibit a compensatory increase in anti-inflammatory cytokines. VBD subjects differed from controls in expression of 10 miRNAs of predicted importance for pain and estrogen signaling. VBD + IBS subjects differed from controls in expression of 11 miRNAs of predicted importance for pain, cell physiology, and insulin signaling. miRNA expression was correlated with pain-relevant phenotypes and cytokine levels. These results suggest that miRNAs represent a valuable tool for differentiating VBD subtypes (localized pain with apparent peripheral neurosensory disruption vs widespread pain with a central sensory contribution) that may require different treatment approaches.

Interleukin-33 in Tissue Homeostasis, Injury, and Inflammation

Interleukin-33 (IL-33) is a nuclear-associated cytokine of the IL-1 family originally described as a potent inducer of allergic type 2 immunity. IL-33 signals via the receptor ST2, which is highly expressed on group 2 innate lymphoid cells (ILC2s) and T helper 2 (Th2) cells, thus underpinning its association with helminth infection and allergic pathology. Recent studies have revealed ST2 expression on subsets of regulatory T cells, and for a role for IL-33 in tissue homeostasis and repair that suggests previously unrecognized interactions within these cellular networks. IL-33 can participate in pathologic fibrotic reactions, or, in the setting of microbial invasion, can cooperate with inflammatory cytokines to promote responses by cytotoxic NK cells, Th1 cells, and CD8(+) T cells. Here, we highlight the regulation and function of IL-33 and ST2 and review their roles in homeostasis, damage, and inflammation, suggesting a conceptual framework for future studies.

Hormonal regulation of the immune microenvironment in the mammary gland

It is well established that the development and homeostasis of the mammary gland are highly dependent upon the actions of ovarian hormones progesterone and estrogen, as well as the availability of prolactin for the pregnant and lactating gland. More recently it has become apparent that immune system cells and cytokines play essential roles in both mammary gland development as well as breast cancer. Here, we review hormonal effects on mammary gland biology during puberty, menstrual cycling, pregnancy, lactation and involution, and dissect how hormonal control of the immune system may contribute to mammary development at each stage via cytokine secretion and recruitment of macrophages, eosinophils, mast cells and lymphocytes. Collectively, these alterations may create an immunotolerant or inflammatory immune environment at specific developmental stages or phases of the menstrual cycle. Of particular interest for further research is investigation of the combinatorial actions of progesterone and estrogen during the luteal phase of the menstrual cycle and key developmental points where the immune system may play an active role both in mammary development as well as in the creation of an immunotolerant environment, thereby affecting breast cancer risk.