Mini‐review: Wound healing of amnion and macrophages

Modulation of macrophages by a phillyrin-loaded thermosensitive hydrogel promotes skin wound healing in mice

BACKGROUND

Impaired wound healing in traumatic skin injuries remains a severe clinical challenge due to impaired re-vascularization, harmful bacteria infection, and inflammation dysregulation. Macrophages are recognized as prominent immune cells in tissue regeneration and wound healing. Consequently, the modulation of macrophages provides a promising therapeutic target for wound healing disorders. Here, we aimed to explore whether a novel constructed combination of thermosensitive hydrogel Pluronic F-127 (PF-127) and phillyrin (PH, the main active compound of forsythia suspensa) could improve skin wound healing.

METHODS

Firstly, the biological effects of pH on the phenotype and inflammation of macrophages were assessed by flow cytometry and ELISA. The biocompatibility of the PF-127 plus PH combination was investigated on keratinocytes and red blood cells. The biological effect of PF-127/PH hydrogel on the migratory ability of keratinocytes in vitro was evaluated using the scratch and transwell migration assays. In addition,S. aureusandE. coliwere employed to test the antibacterial properties of the PF-127 plus PH combination. Finally, PF-127 plus PH scaffold was appliedto the full-thickness skin defect in mice. Histomorphological evaluation and immunochemistry were performed to explore the wound-healing activity of PF-127/PH hydrogel.

RESULTS

PH can promote the polarization of macrophages from the M1 (pro-inflammatory) phenotype to the M2 (anti-inflammatory) phenotype. The PF-127/PH hydrogel was highly biocompatible and showed a potent stimulative effect on the migration of keratinocytesin vitro. The combination of PF-127 and PH exerted a pronounced antibacterial activity onS. aureusandE. coli in vitro.PF-127/PH hydrogel potently accelerates the healing of full-thickness skin defects by promoting skin cell proliferation, accelerating angiogenesis, and inhibiting inflammation.

CONCLUSIONS

Our study suggests that PF-127/PH hydrogel has excellent potential for treating traumatic skin defects.

FPR1 Antagonist (BOC-MLF) Inhibits Amniotic Epithelial-mesenchymal Transition

OBJECTIVE

Premature rupture of membranes (PROM) is a common pregnancy disorder that is closely associated with structural weakening of fetal membranes. Studies have found that formyl peptide receptor 1 (FPR1) activates inflammatory pathways and amniotic epithelialmesenchymal transition (EMT), stimulates collagen degradation, and leads to membrane weakening and membrane rupture. The purpose of this study was to investigate the anti-inflammatory and EMT inhibitory effects of FPR1 antagonist (BOC-MLF) to provide a basis for clinical prevention of PROM.

METHODS

The relationship between PROM, FPR1, and EMT was analyzed in human fetal membrane tissue and plasma samples using Western blotting, PCR, Masson staining, and ELISA assays. Lipopolysaccharide (LPS) was used to establish a fetal membrane inflammation model in pregnant rats, and BOC-MLF was used to treat the LPS rat model. We detected interleukin (IL)-6 in blood from the rat hearts to determine whether the inflammatory model was successful and whether the anti-inflammatory treatment was effective. We used electron microscopy to analyze the structure and collagen expression of rat fetal membrane.

RESULTS

Western blotting, PCR and Masson staining indicated that the expression of FPR1 was significantly increased, the expression of collagen was decreased, and EMT appeared in PROM. The rat model indicated that LPS caused the collapse of fetal membrane epithelial cells, increased intercellular gaps, and decreased collagen. BOC-MLF promoted an increase in fetal membrane collagen, inhibited EMT, and reduced the weakening of fetal membranes.

CONCLUSION

The expression of FPR1 in the fetal membrane of PROM was significantly increased, and EMT of the amniotic membrane was obvious. BOC-MLF can treat inflammation and inhibit amniotic EMT.

The role of intraamniotic inflammation in threatened midtrimester miscarriage

BACKGROUND

The assessment and management of patients with threatened midtrimester miscarriage is a clinical challenge because the etiology of this condition is poorly understood.

OBJECTIVE

This study aimed to examine the frequency of intraamniotic infection or inflammation and the effect of antibiotics in patients presenting with regular uterine contractions and intact membranes before 20 weeks of gestation.

STUDY DESIGN

This retrospective study comprised patients who met the following criteria: (1) singleton gestation, (2) gestational age before 20 weeks, (3) the presence of regular uterine contractions confirmed by a tocodynamometer (8 or more contractions in 60 minutes), (4) intact amniotic membranes, and (5) transabdominal amniocentesis performed for the evaluation of the microbiologic and inflammatory status of the amniotic cavity. Samples of amniotic fluid were cultured for aerobic and anaerobic bacteria and genital mycoplasmas, and polymerase chain reaction was performed to detect Ureaplasma species. Amniotic fluid was tested for white blood cell counts and matrix metalloproteinase-8 concentrations to diagnose intraamniotic inflammation. Patients with intraamniotic inflammation, or intraamniotic infection, were treated with antibiotics (a combination of ceftriaxone, clarithromycin, and metronidazole). Treatment success was defined as the resolution of intraamniotic infection/inflammation at the follow-up amniocentesis or delivery after 34 weeks of gestation.

RESULTS

1) Intraamniotic inflammation was present in 88% (15/17) of patients, whereas infection was detectable in only 2 cases; 2) objective evidence of resolution of intraamniotic inflammation after antibiotic treatment was demonstrated in 100% (4/4) of patients who underwent a follow-up amniocentesis; 3) 30% (5/15) of women receiving antibiotics delivered after 34 weeks of gestation (3 of the 5 patients had a negative follow-up amniocentesis, and 2 of the women were without a follow-up amniocentesis); 4) the overall treatment success of antibiotics was 40% (6/15; 4 cases of objective evidence of resolution of intra-amniotic inflammation and 5 cases of delivery after 34 weeks of gestation).

CONCLUSION

The prevalence of intraamniotic inflammation in patients who presented with a threatened midtrimester miscarriage was 88% (15/17), and, in most cases, microorganisms could not be detected. Antibiotic treatment, administered to patients with intraamniotic inflammation, was associated with either objective resolution of intraamniotic inflammation or delivery after 34 weeks of gestation in 40% (6/15) of the cases.