Bioactive metabolites of OMEGA-6 and OMEGA-3 fatty acids are associated with inflammatory cytokine concentrations in maternal and infant plasma at the time of delivery

BACKGROUND & AIMS

Inflammation is necessary for a healthy pregnancy. However, unregulated or excessive inflammation during pregnancy is associated with severe maternal and infant morbidities, such as pre-eclampsia, abnormal infant neurodevelopment, or preterm birth. Inflammation is regulated in part by the bioactive metabolites of omega-6 (n-6) and omega-3 (n-3) fatty acids (FAs). N-6 FAs have been shown to promote pro-inflammatory cytokine environments in adults, while n-3 FAs have been shown to contribute to the resolution of inflammation; however, how these metabolites affect maternal and infant inflammation is still uncertain. The objective of this study was to predict the influence of n-6 and n-3 FA metabolites on inflammatory biomarkers in maternal and umbilical cord plasma at the time of delivery.

METHODS

Inflammatory biomarkers (IL-1β, IL-2, IL-6, IL-8, IL-10, and TNFα) for maternal and umbilical cord plasma samples in 39 maternal-infant dyads were analyzed via multi-analyte bead array. Metabolites of n-6 FAs (arachidonic acid and linoleic acid) and n-3 FAs (eicosapentaenoic acid and docosahexaenoic acid) were assayed via liquid chromatography-mass spectrometry. Linear regression models assessed relationships between maternal and infant inflammatory markers and metabolite plasma concentrations.

RESULTS

Increased plasma concentrations of maternal n-6 metabolites were predictive of elevated pro-inflammatory cytokine concentrations in mothers; similarly, higher plasma concentrations of umbilical cord n-6 FA metabolites were predictive of elevated pro-inflammatory cytokine concentrations in infants. Higher plasma concentrations of maternal n-6 FA metabolites were also predictive of elevated pro-inflammatory cytokines in infants, suggesting that maternal n-6 FA status has an intergenerational impact on the inflammatory status of the infant. In contrast, maternal and cord plasma concentrations of n-3 FA metabolites had a mixed effect on inflammatory status in mothers and infants, which may be due to the inadequate maternal dietary intake of n-3 FAs in our study population.

CONCLUSIONS

Our results reveal that maternal FA status may have an intergenerational impact on the inflammatory status of the infant. Additional research is needed to identify how dietary interventions that modify maternal FA intake prior to or during pregnancy may impact maternal and infant inflammatory status and associated long-term health outcomes.

MATLAB-Based Algorithm and Software for Analysis of Wavy Collagen Fibers

Knowledge of soft tissue fiber structure is necessary for accurate characterization and modeling of their mechanical response. Fiber configuration and structure informs both our understanding of healthy tissue physiology and of pathological processes resulting from diseased states. This study develops an automatic algorithm to simultaneously estimate fiber global orientation, abundance, and waviness in an investigated image. To our best knowledge, this is the first validated algorithm which can reliably separate fiber waviness from its global orientation for considerably wavy fibers. This is much needed feature for biological tissue characterization. The algorithm is based on incremental movement of local regions of interest (ROI) and analyzes two-dimensional images. Pixels belonging to the fiber are identified in the ROI, and ROI movement is determined according to local orientation of fiber within the ROI. The algorithm is validated with artificial images and ten images of porcine trachea containing wavy fibers. In each image, 80-120 fibers were tracked manually to serve as verification. The coefficient of determination R2 between curve lengths and histograms documenting the fiber waviness and global orientation were used as metrics for analysis. Verification-confirmed results were independent of image rotation and degree of fiber waviness, with curve length accuracy demonstrated to be below 1% of fiber curved length. Validation-confirmed median and interquartile range of R2, respectively, were 0.90 and 0.05 for curved length, 0.92 and 0.07 for waviness, and 0.96 and 0.04 for global orientation histograms. Software constructed from the proposed algorithm was able to track one fiber in about 1.1 s using a typical office computer. The proposed algorithm can reliably and accurately estimate fiber waviness, curve length, and global orientation simultaneously, moving beyond the limitations of prior methods.

Fatty Acids, Amphiregulin Production, and Lung Function in a Cohort of Midwestern Veterans

Rationale

The relationship between many fatty acids and respiratory outcomes remains unclear, especially with regard to mechanistic actions. Altered regulation of the process of lung repair is a key feature of chronic lung disease and may impact the potential for pulmonary rehabilitation, but underlying mechanisms of lung repair following injury or inflammation are not well-studied. The epidermal growth factor receptor agonist amphiregulin (AREG) has been demonstrated to promote lung repair following occupational dust exposure in animals. Studies suggest the polyunsaturated fatty acid (PUFA) docosahexaenoic acid (DHA) may enhance the production of AREG. The objective of this study was to determine the relationship between fatty acids and lung function in a population of veterans and determine if fatty acid status is associated with concentrations of AREG.

Materials and Methods

Data were collected from a cross-sectional study of veterans within the Nebraska-Western Iowa Health Care System. Whole blood assays were performed to quantify AREG concentrations via a commercially available ELISA kit. Fatty acids from plasma samples from the same patients were measured using gas-liquid chromatography. Intakes of fatty acids were quantified with a validated food frequency questionnaire. Linear regression models were used to determine whether plasma fatty acids or intakes of fatty acids predicted lung function or AREG concentrations. A p < 0.05 was considered statistically significant.

Results

Ninety participants were included in this analysis. In fully adjusted models, plasma fatty acids were associated with AREG production, including the PUFA eicosapentaenoic acid (EPA) (β = 0.33, p = 0.03) and the monounsaturated fatty acid octadecenoic acid: (β = −0.56, p = 0.02). The omega-3 PUFA docosapentaenoic acid (DPA) was positively associated with lung function (β = 0.28, p = 0.01; β = 26.5, p = 0.05 for FEV₁/FVC ratio and FEV₁ % predicted, respectively), as were the omega-6 PUFAs eicosadienoic acid (β = 1.13, p < 0.001; β = 91.2, p = 0.005 for FEV₁/FVC ratio and FEV₁ % predicted, respectively) and docosadienoic acid (β = 0.29, p = 0.01 for FEV₁/FVC ratio). Plasma monounsaturated and saturated fatty acids were inversely associated with lung function.

Conclusion

Opposing anti- and pro-inflammatory properties of different fatty acids may be associated with lung function in this population, in part by regulating AREG induction.

Resistin-like molecule alpha (RELMα) dampens lung inflammation and promotes wound healing in helminth infection and a 3D lung repair model

RELMα is a small secreted and immunoregulatory protein, also known as hypoxia-induced mitogenic factor (HIMF) and found in inflammatory zone (FIZZ). RELMα, produced by macrophages and epithelial cells in the lung and intestine, has recently been shown by our lab and others to induce wound healing during Nippostrongylus brasiliensis (Nb) infection. However, the mechanisms by which RELMα activates wound healing pathways and what cell-types are activated by RELMα are unclear. We generated constitutive RELMα−/−/TdTomato-red (TdT) reporter mice to delete the RELMα gene and track RELMα promoter activity. We found that following Nb infection, RELMα−/− macrophages exhibited reduced expression of genes associated with wound healing such as Arg1, Mmp19 and Pdgfra. To complement the RELMα−/− mouse in vivo studies, a new endotoxin-free RELMα-human Fc fusion protein was constructed and purified. A RELMα capture assay with the fusion protein demonstrated that RELMα binds to macrophage cell line RAW 264.7. Moreover, 3D lung scaffold and wound healing assays showed that RELMα-Fc promoted tissue repair by lung epithelial cells and mesenchymal stem cells. Lastly, RELMα function in vivo was characterized by RELMα-Fc fusion protein treatment of Nb-infected RELMα−/−/TdT mice, which downregulated immune cell recruitment in the lung compared to control Fc. Ongoing studies include identification of the RELMα receptor using the RELMα fusion proteins and testing whether the wound healing properties of RELMα are effective in the intestine following Heligosomoides polygyrus infection.

The role of amyloid precursor-like protein 2 in Ewing’s sarcoma resistance to immunity (48.3)

Metastasized Ewing’s sarcoma, a childhood cancer of the bone, has a dismal 20-30% 5-year survival rate, despite multi-modal therapy. Ewing’s sarcoma cells have been shown to escape elimination by the immune system. We have found that several Ewing’s sarcoma cell lines express substantial levels of amyloid precursor-like protein 2 (APLP2). We sought to characterize cellular changes associated with Ewing’s sarcoma cells that avoid immune recognition, with emphasis on the function of APLP2 in this process. Ewing’s sarcoma cells that survived exposure to lymphokine-activated killer (LAK) cells exhibited higher levels of APLP2 expression, suggesting that elevated APLP2 in these cells may contribute to resistance to apoptotic cell death mediated by immune effectors. Consistent with this theory, we demonstrated that LAK-challenged cells have a reduced tendency to arrest in G2/M and to undergo apoptosis following exposure to gamma-irradiation. Transient transfection of a Ewing’s sarcoma cell line with APLP2 reduced irradiation-mediated G2/M arrest and apoptosis. IFN-gamma (a cytokine produced by LAK, NK and T cells) was found to up-regulate APLP2 production in a Ewing’s sarcoma cell line in vitro. This effect of IFN-gamma may contribute to the known ability of IFN-gamma to protect tumor cells from LAK-mediated lysis. Overall, our findings from these studies increase our understanding of mechanisms regulating immune recognition of Ewing’s sarcoma cells.

Hypocalcemia induced by foscarnet (Foscavir) infusion in dogs

Foscarnet (Foscavir) is an antiviral drug for intravenous (i.v.) treatment of cytomegalovirus (CMV) retinitis in immunocompromised patients. The drug forms complexes with divalent metal ions such as Ca2+ and serum calcium levels may be affected during its i.v. infusion. In this study, the effect on calcium homeostasis was investigated during daily 8-hr infusions of foscarnet in dogs. After priming infusions of 40 or 80 mg/kg administered during 0.5 hr, maintenance infusion rates were 46 or 91 mg/kg/hr (total daily doses of 410 or 810 mg/kg). At the low infusion rate, foscarnet was administered for 5 consecutive days. The mean plateau serum concentration was 0.56 mmol/liter and the main clinical sign was vomiting. Total serum calcium was reduced from about 2.5 to 2.0 mmol/liter and ionized calcium from 1.3 to 0.9 mmol/liter. Parathyroid hormone (PTH) levels in serum were elevated three to six times while calcitriol (1,25-(OH)2D3) levels were unaffected. At the high infusion rate, treatment was discontinued after 1-2 days of dosing due to pronounced adverse clinical signs such as extensive vomitings, apathy, ataxia, and muscle spasms. The mean serum plateau concentration of foscarnet at this dose level was 1.2 mmol/liter. Total serum calcium was reduced from 2.5 to 1.6 mmol/liter and ionized calcium from 1.3 to 0.7 mmol/liter. PTH as well as 1,25-(OH)2D3 levels in serum were elevated. Total and ionized calcium levels were normalized within 16 hr after stopping drug treatment. The results showed that foscarnet infusion affects calcium homeostasis and that calcium monitoring might be considered in the clinical use of the drug.

Determination of ampicillin in biological fluids by coupled-column liquid chromatography and post-column derivatization

A rapid and sensitive high-performance liquid chromatographic method has been developed for the determination of ampicillin in plasma and urine. The method involves a simple deproteinization step and separation on a coupled-column chromatographic system followed by post-column derivatization and fluorescence detection. The method has been used for the determination of ampicillin in various clinical studies. The high sensitivity makes it especially useful for small sample volumes, e.g. samples from pediatric patients.

Determination of phosphonoformate (foscarnet) in biological fluids by ion-pair reversed-phase liquid chromatography

Bioanalytical liquid chromatographic methods for the determination of phosphonoformate (foscarnet) have been developed. Biological fluids, after simple pre-treatment (ultrafiltration and/or treatment with charcoal), were injected into a reversed-phase liquid chromatographic system with electrochemical detection. Foscarnet was retained as an ion pair with tetrahexylammonium; addition of pyrophosphate was necessary in order to obtain an acceptable peak. This additive could also be used for the fine regulation of the retention to achieve the necessary selectivity.