The IL-33:ST2 axis is unlikely to play a central fibrogenic role in idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a devastating interstitial lung disease (ILD) with limited treatment options. Interleukin-33 (IL-33) is proposed to play a role in the development of IPF however the exclusive use of prophylactic dosing regimens means that the therapeutic benefit of targeting this cytokine in IPF is unclear.

METHODS

IL-33 expression was assessed in ILD lung sections and human lung fibroblasts (HLFs) by immunohistochemistry and gene/protein expression and responses of HLFs to IL-33 stimulation measured by qPCR. In vivo, the fibrotic potential of IL-33:ST2 signalling was assessed using a murine model of bleomycin (BLM)-induced pulmonary fibrosis and therapeutic dosing with an ST2-Fc fusion protein. Lung and bronchoalveolar lavage fluid were collected for measurement of inflammatory and fibrotic endpoints. Human precision-cut lung slices (PCLS) were stimulated with transforming growth factor-β (TGFβ) or IL-33 and fibrotic readouts assessed.

RESULTS

IL-33 was expressed by fibrotic fibroblasts in situ and was increased by TGFβ treatment in vitro. IL-33 treatment of HLFs did not induce IL6, CXCL8, ACTA2 and COL1A1 mRNA expression with these cells found to lack the IL-33 receptor ST2. Similarly, IL-33 stimulation had no effect on ACTA2, COL1A1, FN1 and fibronectin expression by PCLS. Despite having effects on inflammation suggestive of target engagement, therapeutic dosing with the ST2-Fc fusion protein failed to reduce BLM-induced fibrosis measured by hydroxyproline content or Ashcroft score.

CONCLUSIONS

Together these findings suggest the IL-33:ST2 axis does not play a central fibrogenic role in the lungs with therapeutic blockade of this pathway unlikely to surpass the current standard of care for IPF.

Evaluation of various inclusion rates of organic zinc either as polysaccharide or proteinate complex on the growth performance, plasma, and excretion of nursery pigs1

Three experiments were conducted to evaluate the effects of feeding dietary concentrations of organic Zn as a Zn-polysaccharide (Quali Tech Inc., Chaska, MN) or as a Zn-proteinate (Alltech Inc., Nicholasville, KY) on growth performance, plasma concentrations, and excretion in nursery pigs compared with pigs fed 2,000 ppm inorganic Zn as ZnO. Experiments 1 and 2 were growth experiments, and Exp. 3 was a balance experiment, and they used 306, 98, and 20 crossbred pigs, respectively. Initially, pigs averaged 17 d of age and 5.2 kg BW in Exp. 1 and 2, and 31 d of age and 11.2 kg BW in Exp. 3. The basal diets for Exp. 1, 2, and 3 contained 165 ppm supplemental Zn as ZnSO4 (as-fed basis), which was supplied from the premix. In Exp. 1, the Phase 1 (d 1 to 14) basal diet was supplemented with 0, 125, 250, 375, or 500 ppm Zn as Zn-polysaccharide (as-fed basis) or 2,000 ppm Zn as ZnO (as-fed basis). All pigs were then fed the same Phase 2 (d 15 to 28) and Phase 3 (d 29 to 42) diets. In Exp. 2, both the Phase 1 and 2 basal diets were supplemented with 0, 50, 100, 200, 400, or 800 ppm Zn as Zn-proteinate (as-fed basis) or 2,000 ppm Zn as ZnO (as-fed basis). For the 28-d Exp. 3, the Phase 2 basal diet was supplemented with 0, 200, or 400 ppm Zn as Zn-proteinate, or 2,000 ppm Zn as ZnO (as-fed basis). All diets were fed in meal form. In Exp. 1, 2, and 3, pigs were bled on d 14, 28, or 27, respectively, to determine plasma Zn and Cu concentrations. For all three experiments, there were no overall treatment differences in ADG, ADFI, or G:F (P = 0.15, 0.22, and 0.45, respectively). However, during wk 1 of Exp. 1, pigs fed 2,000 ppm Zn as ZnO had greater (P < or = 0.05) ADG and G:F than pigs fed the basal diet. In all experiments, pigs fed a diet containing 2,000 ppm Zn as ZnO had higher plasma Zn concentrations (P < 0.10) than pigs fed the basal diet. In Exp. 1 and 3, pigs fed 2,000 ppm Zn as ZnO had higher fecal Zn concentrations (P < 0.01) than pigs fed the other dietary Zn treatments. In conclusion, organic Zn either as a polysaccharide or a proteinate had no effect on growth performance at lower inclusion rates; however, feeding lower concentrations of organic Zn greatly decreased the amount of Zn excreted.

AGE-SPECIFIC REPRODUCTIVE SUCCESS: EVIDENCE FOR THE SELECTION HYPOTHESIS

Age-specific reproductive success has been demonstrated in many species. Three hypotheses have been raised to explain this general phenomenon: the experience hypothesis based on age-specific reproductive experience, the effort hypothesis based on age-specific reproductive effort, and the selection hypothesis based on progressive disappearance of phenotypes due to variation in individual productivity and survival. We used data from a long-term study of Leach's storm-petrels (Oceanodroma leucorhoa) to present a single test of mutually exclusive predictions about the relationship between early breeding success and longevity. There should be no correlation between early breeding success and longevity under the experience hypothesis, a negative correlation under the effort hypothesis, and a positive correlation under the selection hypothesis. We found a significant (P < 0.0001) positive relationship between success in the first two breeding attempts and longevity in this population of long-lived seabirds, strongly suggesting that low-productivity parents were also less likely to survive early breeding. These data provide some of the strongest support to date for the selection hypothesis.