Publisher Correction: Blocking elevated p38 MAPK restores efferocytosis and inflammatory resolution in the elderly.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Blocking elevated p38 MAPK restores efferocytosis and inflammatory resolution in the elderly.

Increasing age alters innate immune-mediated responses; however, the mechanisms underpinning these changes in humans are not fully understood. Using a human dermal model of acute inflammation, we found that, although inflammatory onset is similar between young and elderly individuals, the resolution phase was substantially impaired in elderly individuals. This arose from a reduction in T cell immunoglobulin mucin receptor-4 (TIM-4), a phosphatidylserine receptor expressed on macrophages that enables the engulfment of apoptotic bodies, so-called efferocytosis. Reduced TIM-4 in elderly individuals was caused by an elevation in macrophage p38 mitogen-activated protein kinase (MAPK) activity. Administering an orally active p38 inhibitor to elderly individuals rescued TIM-4 expression, cleared apoptotic bodies and restored a macrophage resolution phenotype. Thus, inhibiting p38 in elderly individuals rejuvenated their resolution response to be more similar to that of younger people. This is the first resolution defect identified in humans that has been successfully reversed, thereby highlighting the tractability of targeting pro-resolution biology to treat diseases driven by chronic inflammation.

Treatment of periodontitis reduces systemic inflammation in type 2 diabetes.

AIMS: To assess the impact of periodontal treatment on systemic inflammation in type 2 diabetes. MATERIALS AND METHODS: Adults with type 2 diabetes (n = 83) and without diabetes (controls, n = 75) were recruited, and participants with periodontitis received periodontal treatment and 12 months' follow-up. Biomarkers for periodontal inflammation (gingival crevicular fluid interleukin-6, tumour necrosis factor-α, interleukin-1ß, interferon-γ, matrix metalloproteinase-8, matrix metalloproteinase-9, adiponectin) and serum markers of inflammation and diabetes control (glycated haemoglobin, high sensitivity C-reactive protein, interleukin-6, tumour necrosis factor-α, interleukin-1ß, interferon-γ, leptin, adiponectin) were measured. Structural equation modelling was used to evaluate periodontal treatment effects on oral and systemic inflammation. RESULTS: Periodontal treatment resulted in significant improvements in clinical status and reductions in gingival crevicular fluid biomarkers from baseline to month 12. Structural equation modelling identified that, at baseline, individuals with diabetes and periodontitis had significantly higher systemic inflammation than non-diabetic controls with periodontitis (Δ = 0.20, p = .002), with no significant differences between groups for oral inflammation. There was a greater reduction in systemic inflammation following periodontal treatment in individuals with diabetes and periodontitis compared to those with periodontitis but not diabetes (Δ = -0.25, p = .01). CONCLUSIONS: Diabetes and periodontitis together appear to increase systemic inflammation, with evidence of reductions following periodontal treatment.

A Prototype Antibody-based Biosensor for Measurement of Salivary MMP-8 in Periodontitis using Surface Acoustic Wave Technology.

Periodontitis is an economically important disease which is highly prevalent worldwide. Current diagnostic approaches are time-consuming and require interpretation of multiple aspects of clinical and radiographic assessment. Chair-side monitoring of inflammatory mediators of periodontitis could provide immediate information about disease activity, which can inform patient management. We aimed to develop a novel prototype biosensor to measure salivary matrix metalloproteinase-8 (MMP-8) using specific antibodies and surface acoustic wave (SAW) technology. The analytical performance of the prototype biosensor was compared to standard enzyme-linked immunosorbent assay (ELISA) using unstimulated saliva samples obtained from patients with periodontitis before and after non-surgical treatment (N = 58), patients with gingivitis (N = 54) and periodontally healthy volunteers (N = 65). Receiver operator characteristic (ROC) analysis for distinguishing periodontitis from health revealed an almost identical performance between the sensor and ELISA assays (area under curve values (AUC): ELISA 0.93; SAW 0.89). Furthermore, both analytical approaches yielded readouts which distinguished between heath, gingivitis and periodontitis, correlated identically with clinical measures of periodontal disease and recorded similar post-treatment decreases in salivary MMP-8 in periodontitis. The assay time for our prototype device is 20 minutes. The prototype SAW biosensor is a novel and rapid method of monitoring periodontitis which delivers similar analytical performance to conventional laboratory assays.

Inflammatory Resolution Triggers a Prolonged Phase of Immune Suppression through COX-1/mPGES-1-Derived Prostaglandin E2.

Acute inflammation is characterized by granulocyte infiltration followed by efferocytosing mononuclear phagocytes, which pave the way for inflammatory resolution. Until now, it was believed that resolution then leads back to homeostasis, the physiological state tissues experience before inflammation occurred. However, we discovered that resolution triggered a prolonged phase of immune suppression mediated by prostanoids. Specifically, once inflammation was switched off, natural killer cells, secreting interferon γ (IFNγ), infiltrated the post-inflamed site. IFNγ upregulated microsomal prostaglandin E synthase-1 (mPGES-1) alongside cyclo-oxygenase (COX-1) within macrophage populations, resulting in sustained prostaglandin (PG)E2 biosynthesis. Whereas PGE2 suppressed local innate immunity to bacterial infection, it also inhibited lymphocyte function and generated myeloid-derived suppressor cells, the net effect of which was impaired uptake/presentation of exogenous antigens. Therefore, we have defined a sequence of post-resolution events that dampens the propensity to develop autoimmune responses to endogenous antigens at the cost of local tissue infection.