TIMP3 Regulates Mammary Epithelial Apoptosis with Immune Cell Recruitment Through Differential TNF Dependence

Post-lactation mammary involution is a homeostatic process requiring epithelial apoptosis and clearance. Given that the deficiency of the extracellular metalloproteinase inhibitor TIMP3 impacts epithelial apoptosis and heightens inflammatory response, we investigated whether TIMP3 regulates these distinct processes during the phases of mammary gland involution in the mouse. Here we show that TIMP3 deficiency leads to TNF dysregulation, earlier caspase activation and onset of mitochondrial apoptosis. This accelerated first phase of involution includes faster loss of initiating signals (STAT3 activation; TGFβ3) concurrent with immediate luminal deconstruction through E-cadherin fragmentation. Epithelial apoptosis is followed by accelerated adipogenesis and a greater macrophage and T-cell infiltration in Timp3−/− involuting glands. Crossing in Tnf deficiency abrogates caspase 3 activation, but heightens macrophage and T-cell influx into Timp3−/− glands. The data indicate that TIMP3 differentially impacts apoptosis and inflammatory cell influx, based on involvement of TNF, during the process of mammary involution. An understanding of the molecular factors and wound healing microenvironment of the postpartum mammary gland may have implications for understanding pregnancy-associated breast cancer risk

Skating on thin ice: stimulant use and sub‐optimal adherence to HIV pre‐exposure prophylaxis

IntroductionStimulant and heavy alcohol use are prevalent and associated with elevated risk for HIV seroconversion among men who have sex with men (MSM) and transgender women. In addition, each can pose difficulties for antiretroviral adherence among people living with HIV. Scant research has examined the associations of stimulant and heavy alcohol use with adherence to daily oral pre‐exposure prophylaxis (PrEP) among MSM and transgender women. To address this gap in the literature, we evaluated the hypothesis that stimulant use and binge drinking are prospectively associated with sub‐optimal PrEP adherence.MethodsWe analysed data from participants in a nested case‐cohort in the iPrEx open label extension. Stimulant use (i.e. powder cocaine, crack‐cocaine, cocaine paste, methamphetamine, cathinone) and binge drinking (i.e. ≥5 drinks in a single day) in the last 30 days were assessed. Baseline urine was tested for stimulants using immunoassays to reduce misclassification. Sub‐optimal adherence was defined as tenofovir drug concentrations in dried blood spots less than 700 fmol per punch, indicative of less than four doses per week. We tested the prospective association of stimulant use and binge drinking with sub‐optimal adherence at the 4‐week follow‐up visit.Results and DiscussionData from 330 participants were analysed. The majority of the participants were MSM (89%) with a median age at baseline of 29 years (interquartile range 24 to 39). Approximately 16% (52/330) used stimulants and 22% (72/330) reported binge drinking in the last 30 days. Stimulant users had fivefold greater odds of sub‐optimal PrEP adherence compared to non‐users in adjusted analysis (adjusted odds ratio [aOR] 5.04; [95% CI 1.35 to 18.78]). Self‐reported binge drinking was not significantly associated with sub‐optimal adherence after adjusting for stimulant use and baseline confounders (aOR 1.16 [0.49 to 2.73]). Depressive symptoms, being transgender, and number of sex partners were also not significantly associated with sub‐optimal PrEP adherence (p > 0.05).ConclusionsStimulant use is a risk factor for sub‐optimal PrEP adherence in the month following PrEP initiation. Comprehensive prevention approaches that reduce stimulant use may optimize PrEP adherence. Creating adherence plans that specifically address PrEP dosing in the context of ongoing stimulant use should also be considered.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142946/1/jia225103.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142946/2/jia225103_am.pd

Inflammation and breast cancer. Metalloproteinases as common effectors of inflammation and extracellular matrix breakdown in breast cancer

Two rapidly evolving fields are converging to impact breast cancer: one has identified novel substrates of metalloproteinases that alter immune cell function, and the other has revealed a role for inflammation in human cancers. Evidence now shows that the mechanisms underlying these two fields interact in the context of breast cancer, providing new opportunities to understand this disease and uncover novel therapeutic strategies. The metalloproteinase class of enzymes is well studied in mammary gland development and physiology, but mostly in the context of extracellular matrix modification. Aberrant metalloproteinase expression has also been implicated in breast cancer progression, where these genes act as tumor modifiers. Here, we review how the metalloproteinase axis impacts mammary physiology and tumorigenesis and is associated with inflammatory cell influx in human breast cancer, and evaluate its potential as a regulator of inflammation in the mammary gland

Inhibition of E-cadherin fragmentation and TNF signaling by recombinant TIMP3.

<p>Pellets containing vehicle control (ctrl) or recombinant human TIMP3 (rT3) were implanted at the beginning of involution and tissues were harvested at day 3 of involution. (<i>A</i>) Pellets containing recombinant TIMP3 blocked E-cadherin fragmentation at 3i in <i>Timp3</i>^{−<i>/</i>−} (n = 3). (<i>B</i>) The increase in TNF levels at 3i in <i>Timp3</i>^{−<i>/</i>−} tissue glands was reversed by recombinant TIMP3 as measured by ELISA. (<i>C</i>) Caspase 8 activation at 3i was only abrogated in <i>Timp3</i>^{−<i>/</i>−} regressed tissue that was reconstituted with recombinant TIMP3. Bar graphs are expressed as mean ± SEM (* = <i>P</i><0.01; n = 3).</p

Increased TNF levels and apoptotic signaling in <i>Timp3</i>β involuting glands.

<p>(<i>A</i>) TNF levels as assessed by ELISA at different involution timepoints starting from day 10L until day 7i revealed higher levels of TNF levels in <i>Timp3</i>^{−<i>/</i>−} glands (n = 3) compared to wild-type (WT, n = 3) both prior to the onset of involution and as an earlier rebound. (<i>B</i>) Representative western blot analyses of lysates from different involution timepoints probed for caspase 8 (Casp 8), Apaf-1, cytochrome c (Cyt c), caspase 9 (Casp 9; top band represents pro-caspase 9, bottom band represents cleaved caspase 9; ND = not determined for 7i), cleaved caspase 3 (Casp 3), Apoptosis-inducing factor (AIF), and Second mitochondria-derived activator of caspase (SMAC). (<i>C</i>) Immunofluorescence and co-localization of mitochondria (MitoTracker) and cytochrome c revealed earlier release of cytochrome c from the mitochondria (red signal, arrows) in <i>Timp3</i>^{−<i>/</i>−} luminal cells, as well as cells that have detached and were shed into the lumen by 1i, than in wild-type at 3i. Bar graphs are expressed as mean ± SEM (* = <i>P</i><0.02). Scale bar = 30 µm.</p

Involvement of matrix metalloproteinases (MMPs), a disintegrin and a metalloproteinase (ADAMs), and tissue inhibitor of metalloproteinases (TIMPs) in immune function

The substrate repertoire generated through shedding, clipping, and regulated-intramembrane processing (RIPping) provides insight into the role of the metalloproteinase axis in immune cell adhesion and migration, the generation of chemokine gradients, and humoral and cell-mediated immunity [9]. ICAM, intracellular adhesion molecule; IL, interleukin; TNF, tumor necrosis factor; TNFR, TNF receptor; VCAM, vascular cell adhesion molecule.<p><b>Copyright information:</b></p><p>Taken from "Inflammation and breast cancer. Metalloproteinases as common effectors of inflammation and extracellular matrix breakdown in breast cancer"</p><p>http://breast-cancer-research.com/content/10/2/205</p><p>Breast Cancer Research : BCR 2008;10(2):205-205.</p><p>Published online 31 Mar 2008</p><p>PMCID:PMC2397522.</p><p></p

Schematic representation of the shifted timeline of involution in <i>Timp3</i>⁻^<i>/</i>− mammary glands.

<p>The timing and intensity of epithelial apoptosis, adipogenesis, and immune cell influx are depicted by a solid line for wild-type and a dotted line for <i>Timp3</i>^{−<i>/</i>−}βmammary gland involution.</p

Mapping of priming and adipogenic signals in <i>Timp3</i>⁻^<i>/</i>− mammary involution.

<p>Representative western blot analyses of lysates from wild-type (WT) and <i>Timp3</i>^{−<i>/</i>−} mammary glands at different involution timepoints starting from day 10L until day 7i probed for phosphorylated STAT3 (P-STAT3), total STAT3, TGF-β3, and the adipogenic markers: CEBPβ, PPAR-γ, and ALBP.</p