Characterization of the Inflammatory Response Evoked by Bacterial Membrane Vesicles in Intestinal Cells Reveals an RIPK2-Dependent Activation by Enterotoxigenic Escherichia coli Vesicles

Although the immunomodulatory potency of bacterial membrane vesicles (MVs) is widely acknowledged, their interactions with host cells and the underlying signaling pathways have not been well studied. Herein, we provide a comparative analysis of the proinflammatory cytokine profile secreted by human intestinal epithelial cells exposed to MVs derived from 32 gut bacteria. In general, outer membrane vesicles (OMVs) from Gram-negative bacteria induced a stronger proinflammatory response than MVs from Gram-positive bacteria. However, the quality and quantity of cytokine induction varied between MVs from different species, highlighting their unique immunomodulatory properties. OMVs from enterotoxigenic Escherichia coli (ETEC) were among those showing the strongest proinflammatory potency. In depth analyses revealed that the immunomodulatory activity of ETEC OMVs relies on a so far unprecedented two-step mechanism, including their internalization into host cells followed by intracellular recognition. First, OMVs are efficiently taken up by intestinal epithelial cells, which mainly depends on caveolin-mediated endocytosis as well as the presence of the outer membrane porins OmpA and OmpF on the MVs. Second, lipopolysaccharide (LPS) delivered by OMVs is intracellularly recognized by novel caspase- and RIPK2-dependent pathways. This recognition likely occurs via detection of the lipid A moiety as ETEC OMVs with underacylated LPS exhibited reduced proinflammatory potency but similar uptake dynamics compared to OMVs derived from wild-type (WT) ETEC. Intracellular recognition of ETEC OMVs in intestinal epithelial cells is pivotal for the proinflammatory response as inhibition of OMV uptake also abolished cytokine induction. The study signifies the importance of OMV internalization by host cells to exercise their immunomodulatory activities. IMPORTANCE The release of membrane vesicles from the bacterial cell surface is highly conserved among most bacterial species, including outer membrane vesicles (OMVs) from Gram-negative bacteria as well as vesicles liberated from the cytoplasmic membrane of Gram-positive bacteria. It is becoming increasingly evident that these multifactorial spheres, carrying membranous, periplasmic, and even cytosolic content, contribute to intra- and interspecies communication. In particular, gut microbiota and the host engage in a myriad of immunogenic and metabolic interactions. This study highlights the individual immunomodulatory activities of bacterial membrane vesicles from different enteric species and provides new mechanistic insights into the recognition of ETEC OMVs by human intestinal epithelial cells.

Characterisation of a High-Performance Al-Zn-Mg-Cu Alloy Designed for Wire Arc Additive Manufacturing

Ever-increasing demands of industrial manufacturing regarding mechanical properties require the development of novel alloys designed towards the respective manufacturing process. Here, we consider wire arc additive manufacturing. To this end, Al alloys with additions of Zn, Mg and Cu have been designed considering the requirements of good mechanical properties and limited hot cracking susceptibility. The samples were produced using the cold metal transfer pulse advanced (CMT-PADV) technique, known for its ability to produce lower porosity parts with smaller grain size. After material simulations to determine the optimal heat treatment, the samples were solution heat treated, quenched and aged to enhance their mechanical performance. Chemical analysis, mechanical properties and microstructure evolution were evaluated using optical light microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray fluorescence analysis and X-ray radiography, as well as tensile, fatigue and hardness tests. The objective of this research was to evaluate in detail the mechanical properties and microstructure of the newly designed high-performance Al–Zn-based alloy before and after ageing heat treatment. The only defects found in the parts built under optimised conditions were small dispersed porosities, without any visible cracks or lack of fusion. Furthermore, the mechanical properties are superior to those of commercial 7xxx alloys and remarkably independent of the testing direction (parallel or perpendicular to the deposit beads). The presented analyses are very promising regarding additive manufacturing of high-strength aluminium alloys.

Clear cell carcinoma of the ovary: a distinct histologic type with poor prognosis and resistance to platinum-based chemotherapy in stage III disease

Between 1982 and 1992, 24 women with Stage III clear cell ovarian cancer were identified from the tumor registry. Thirty-four women with Stage III papillary serous tumors treated between 1987 and 1989 were used as a comparison. All patients underwent cytoreductive surgery followed by conventional platinum-based chemotherapy. In the women with clear cell histology, nine (37.5%) had endometriosis in the surgical specimen compared with one (3%) in the papillary serous group (P = 0.002). Ten women (42%) with clear cell histology experienced a thromboembolic event during the course of treatment, compared to six (18%) in the papillary serous group (P = 0.05). In the group with clear cell histology, overall, 70% of women had progressive disease. Fifty-two percent experienced clinical progression while receiving platinum-based chemotherapy. In addition, four patients were found to have progressive disease at second-look laparotomy. Only two patients had a pathologic complete response. In the group with papillary serous histology, 29% overall had progressive disease while on chemotherapy (P = 0.005). The median survival for the women with clear cell histology was 12 months compared to 22 months for those with papillary serous (P = 0.02). For women with clear cell histology, univariate analysis was used to evaluate prognostic factors. Age less than 50 was a poor prognostic factor (P = 0.045). The presence of endometriosis, thromboembolic event, or optimal cytoreduction were not prognostic factors (P = 0.67, P = 0.34, P = 0.39). Patients with advanced clear cell ovarian cancer have a poor response to conventional platinum-based chemotherapy and overall prognosis is poor.

Pseudomyxoma peritonei: a review of 23 cases

OBJECTIVE

To review the experience at the Massachusetts General and Brigham and Women's Hospitals with 23 women treated for pseudomyxoma peritonei between 1961 and 1991.

METHODS

Patients were identified retrospectively from the tumor registry at the Massachusetts General and Brigham and Women's Hospitals, and all charts were reviewed. The median follow-up interval was 2.5 years (range 3 months to 31 years).

RESULTS

The mean age at diagnosis was 58 years (range 26-76). Pseudomyxoma peritonei was found in association with ten (44%) ovarian tumors of borderline malignancy, nine (39%) ovarian cystadenocarcinomas, and four (17%) appendiceal cystadenocarcinomas. Three patients had synchronous tumors in the ovary and appendix. All patients underwent surgical staging and cytoreduction. Eleven patients received postoperative therapy and, of these, nine developed a recurrence; 12 patients received no further therapy and, of these, three developed a recurrence. However, these groups were not pathologically comparable. With respect to survival, of the ten patients with borderline malignancies, seven had no evidence of disease, one was alive with disease, and two died of disease. For the nine patients with ovarian cystadenocarcinomas, three had no evidence of disease, one was alive with disease, and five died of disease (median time to death 18 months). For the four patients with appendiceal carcinomas, two had no disease, one was alive with disease, and one died with disease. Among all 23 patients, 12 (52%) developed a recurrence, with a range of time to first recurrence of 3 months to 19 years. Eight women required at least one additional laparotomy because of accumulation of gelatinous material.

CONCLUSIONS

Although pseudomyxoma peritonei is associated with borderline and well-differentiated tumors, recurrence is common and the prognosis after recurrence is guarded. Involvement of the appendix is common; therefore, appendectomy is indicated when pseudomyxoma is encountered. To date, surgery has been the only effective therapy for this disease, and adjuvant therapy has not been shown conclusively to be of benefit.

Uterine leiomyosarcoma and endometrial stromal sarcoma: lymph node metastases and sites of recurrence

This study was undertaken to examine the incidence and conditions under which lymph node metastases are present and patterns of recurrence in women with uterine leiomyosarcoma (LMS) and endometrial stromal sarcoma (ESS), excluding malignant mixed mesodermal tumors. From 1981 through 1991, 21 women with LMS and 10 women with ESS were treated. Retroperitoneal lymph node dissections were performed in 15 women with LMS and 7 women with ESS. In the women with LMS, 4/15 (26.7%) had lymph node metastases; in each there was disseminated intra-abdominal disease. In the 7 women with ESS, there were no lymph node metastases present. Ten women (47%) with LMS developed recurrences, and 3 (14%) had persistent disease. In the 10 women with ESS, 3 (30%) had recurrences, and 1 (10%) had persistent disease. In total, recurrences involved the lung in 84% of cases. Of the 13 women with recurrences, 7 had undergone lymph node sampling, and all were negative; 4 additional women had no evidence of adenopathy on abdominal-pelvic CT scan. Lymph node metastases were found only with extrauterine disease, and in all of these cases there was rapid progression of the sarcoma. Women without extrauterine disease did not have lymph node metastases detected; however, there was still a high rate (40%) of distant failure. Knowledge of lymph node status had minimal impact on the clinical management of women with uterine LMS and ESS.

Control of astrocyte volume by intracellular and extracellular Ca2+

Astrocytes from primary culture were exposed to conditions that affect intracellular and extracellular Ca2+ concentrations. Astrocyte cell volume was increased approximately 16% after a 30 min exposure to isoosmotic phosphate-buffered saline (PBS) containing the Ca2+ buffer EDTA. Cell volume returned to control values within 30 min of resuspension in normal PBS. Cellular calcium content was not affected by these treatments; however, the recovery of normal cell volume following EDTA exposure was inhibited by 0.1-1.0 mM quinine HCl in a dose-dependent fashion suggesting that a potassium channel controlled by the intracellular Ca2+ concentration is important in this volume response. Intracellular accumulation of an exogenous Ca2+ buffer, BAPTA, also produced cell swelling that persisted following resuspension in normal PBS. Lowering the extracellular Ca2+ concentration with EDTA enhanced the swelling of BAPTA-loaded cells. These data suggest that conditions leading to a decrease in free intracellular Ca2+ concentration may influence astrocyte volume by a mechanism similar to that described in other cell types.

Energy-dependent volume regulation in primary cultured cerebral astrocytes

Cell volume regulation and energy metabolism were studied in primary cultured cerebral astrocytes during exposure to media of altered osmolarity. Cells suspended in medium containing 1/2 the normal concentration of NaCl (hypoosmotic) swell immediately to a volume 40-50% larger than cells suspended in isoosmotic medium. The cell volume in hypoosmotic medium then decreases over 30 min to a volume approximately 25% larger than cells in isoosmotic medium. In hyperosmotic medium (containing twice the normal concentration of NaCl), astrocytes shrink by 29%. Little volume change occurs following this initial shrinkage. Cells resuspended in isoosmotic medium after a 30 min incubation in hypoosmotic medium shrink immediately to a volume 10% less than the volume of cells incubated continuously in isoosmotic medium. Thus, the regulatory volume decrease (RVD) in hypoosmotic medium involves a net reduction of intracellular osmoles. The RVD is partially blocked by inhibitors of mitochondrial electron transport but is unaffected by an inhibitor of glycolysis or by an uncoupler of oxidative phosphorylation. Inhibition of RVD by these metabolic agents is correlated with decreased cellular ATP levels. Ouabain, added immediately after hypoosmotic induced swelling, completely inhibits RVD, but does not alter cell volume if added after RVD has taken place. Ouabain also inhibits cell respiration 27% more in hypoosmotic medium than in isoosmotic medium indicating that the (Na,K)-ATPase-coupled ion pump is more active in the hypoosmotic medium. These data suggest that the cell volume response of astrocytes in hypoosmotic medium involves the net movement of osmoles by a mechanism dependent on cellular energy and tightly coupled to the (Na,K)-ATPase ion pump. This process may be important in the energy-dependent osmoregulation in the brain, a critical role attributed to the astrocyte in vivo.