Contrasting mechanisms by which social isolation and restraint impair healing in male mice.

Stress modulates vital aspects of immune functioning in both human and non-human animals, including tissue repair. For example, dermal wounds heal more slowly and are associated with prolonged inflammation and increased bacterial load in mice that experience chronic physical restraint. Social stressors also negatively affect healing; however, previous studies suggest that the affected healing mechanisms may be stress model-specific. Here, the effects of either social isolation or physical restraint on dermal wound healing (3.5 mm wounds on the dorsum) were compared in hairless male mice. Social isolation beginning 3 weeks prior to wounding delayed healing comparably to physical restraint (12 h/day for eight days), in spite of marked differences in metabolic and hormonal consequences (i.e. body mass) between the two stress models. Additionally, isolated mice exhibited reductions in wound bacterial load and inflammatory gene expression (interleukin-1beta [IL-1ß], monocyte chemoattractant protein [MCP]), whereas restraint significantly increased both of these parameters relative to controls. Experimentally augmenting bacterial concentrations in wounds of isolated mice did not ameliorate healing, whereas this treatment accelerated healing in controls. This work indicates that social isolation and restraint stressors comparably impair healing, but do so through disparate mechanisms and at different phases of healing.

The effects of social isolation on wound healing mechanisms in female mice.

Various stressors impair wound healing in humans and rodents. For example, social isolation delays wound closure in rodents, but the healing mechanisms that underlie this delay have yet to be identified. Here, the effects of three weeks of social isolation on hypothalamic-pituitary-adrenal axis responses and healing factors involved in the inflammatory and proliferative phases of wound healing were assessed in adult female hairless mice. Social isolation reduced basal circulating corticosterone concentrations and increased body and thymus weights compared with group-housed controls. Isolation impaired dermal wound closure by up to 30% and reduced initial total wound bacterial load relative to controls. Inflammatory gene expression in the wounds was not affected by the observed differences in wound bacterial load. However, isolation reduced wound gene expression of keratinocyte growth factor and vascular endothelial growth factor, which are involved in keratinocyte proliferation/migration and angiogenesis during the proliferative phase of healing. These data indicate that social isolation induces healing impairments that may be attributed to reductions in growth factors necessary for proper skin cell proliferation and blood vessel growth during healing. This healing impairment occurred in the absence of both high wound bacterial load and elevated circulating glucocorticoids, which have previously been hypothesized to be required for stress-impaired healing in mice.

Effect of nonsurgical periodontal therapy and strict plaque control on preterm/low birth weight: a randomized controlled clinical trial.

OBJECTIVE: This randomized controlled clinical trial was carried out to assess the effect of comprehensive nonsurgical periodontal treatment and strict plaque control performed during pregnancy on the reduction of preterm and/or low birth weight rates (PTLBW). MATERIAL AND METHODS: Three hundred and three women were randomly allocated to receive periodontal treatment either during pregnancy (n = 147, test group) or after delivery (n = 156, control group). During pregnancy, the control group received only one session of supragingival scaling and oral hygiene instruction. In contrast, the test group received comprehensive periodontal treatment including multiple sessions of scaling and root planing, oral hygiene instructions, and frequent maintenance visits. RESULTS: At baseline, periodontal inflammation was observed in approximately 50% of sites and attachment loss affected <15% of sites. Compared to controls, women in the test group had significant reductions in the percentage of sites with plaque (48.5% vs. 10.3%, p < 0.001), gingival bleeding (23.3% vs. 2.5%, p < 0.001), calculus (21.3% vs. 4.1%, p < 0.001), bleeding on probing (38.1% vs. 2.6%, p < 0.001) and probing depth ≥3 mm (19.97% vs. −2.45%, p < 0.001). No significant differences were observed between the groups in the occurrence of PT (11.7% vs. 9.1%, p = 0.57), LBW (5.6 % vs. 4.1%, p = 0.59), and PTLBW (4.15% vs. 2.60%, p = 0.53). CONCLUSIONS: Comprehensive periodontal treatment and strict plaque control significantly improved periodontal health; however, no reduction of PTLBW rates was observed. Thus, remaining periodontal inflammation posttreatment cannot explain the lack of effect of periodontal treatment on PTLBW. Clinical relevance This study demonstrated that periodontal diseases may be successfully treated during pregnancy. Our results do not support a potential beneficial effect of periodontal treatment on PTLBW.