Trends in social inequality in breastfeeding duration in Denmark 2002-2019.

AIMS: The aim of the present study was to analyse trends in full breastfeeding for at least 4 months across socioeconomic position in Denmark over a 17-year-long period from 2002 to 2019 using parental education as the indicator of socioeconomic position. METHODS: The study used data on full breastfeeding collected between 2002 and 2019 by community health nurses in the collaboration Child Health Database, n=143,075. Data were linked with five categories of parental education from population registers. Social inequality was calculated as both the relative (odds ratio) and absolute social inequality (slope index of inequality). A trend test was conducted to assess changes in social inequality over time. RESULTS: A social gradient in full breastfeeding was found for the entire study period. The odds ratio for not being fully breastfed for at least 4 months ranged from 3.30 (95% confidence interval 2.83-3.84) to 5.09 (95% confidence interval 4.28-6.06) during the study period for infants of parents with the lowest level of education (primary school) compared with infants of parents with the highest level of education (5+ years of university education). The slope index of inequality was between -38.86 and -48.81 during the entire study period, P=0.80. This indicated that both the relative and absolute social inequality in full breastfeeding to at least 4 months of age was unchanged in the study period from 2002 to 2019. CONCLUSIONS: This study showed a persistent relative and absolute social inequality in full breastfeeding for at least 4 months from 2002 to 2019 in Denmark.

A novel approach for production of an active N-terminally truncated Ulp1 (SUMO protease 1) catalytic domain from Escherichia coli inclusion bodies.

The SUMO fusion system is widely used to facilitate recombinant expression and production of difficult-to-express proteins. After purification of the recombinant fusion protein, removal of the SUMO-tag is accomplished by the yeast cysteine protease, SUMO protease 1 (Ulp1), which specifically recognizes the tertiary fold of the SUMO domain. At present, the expression of the catalytic domain, residues 403-621, is used for obtaining soluble and biologically active Ulp1. However, we have observed that the soluble and catalytically active Ulp1403-621 inhibits the growth of E. coli host cells. In the current study, we demonstrate an alternative route for producing active Ulp1 catalytic domain from a His-tagged N-terminally truncated variant, residues 416-621, which is expressed in E. coli inclusion bodies and subsequently refolded. Expressing the insoluble Ulp1416-621 variant is advantageous for achieving higher production yields. Approximately 285 mg of recombinant Ulp1416-621 was recovered from inclusion bodies isolated from 1 L of high cell-density E. coli batch fermentation culture. After Ni2+-affinity purification of inactive and denatured Ulp1416-621 in 7.5 M urea, different refolding conditions with varying l-arginine concentration, pH, and temperature were tested. We have successfully refolded the enzyme in 0.25 M l-arginine and 0.5 M Tris-HCl (pH 7) at room temperature. Approximately 80 mg of active Ulp1416-621 catalytic domain can be produced from 1 L of high cell-density E. coli culture. We discuss the applicability of inclusion body-directed expression and considerations for obtaining high expression yields and efficient refolding conditions to reconstitute the active protein fold.

Interferon lambda 4 signals via the IFNλ receptor to regulate antiviral activity against HCV and coronaviruses.

The IFNL4 gene is a recently discovered type III interferon, which in a significant fraction of the human population harbours a frameshift mutation abolishing the IFNλ4 ORF. The expression of IFNλ4 is correlated with both poor spontaneous clearance of hepatitis C virus (HCV) and poor response to treatment with type I interferon. Here, we show that the IFNL4 gene encodes an active type III interferon, named IFNλ4, which signals through the IFNλR1 and IL-10R2 receptor chains. Recombinant IFNλ4 is antiviral against both HCV and coronaviruses at levels comparable to IFNλ3. However, the secretion of IFNλ4 is impaired compared to that of IFNλ3, and this impairment is not due to a weak signal peptide, which was previously believed. We found that IFNλ4 gets N-linked glycosylated and that this glycosylation is required for secretion. Nevertheless, this glycosylation is not required for activity. Together, these findings result in the paradox that IFNλ4 is strongly antiviral but a disadvantage during HCV infection.