TNF-α-driven inflammation and mitochondrial dysfunction define the platelet hyperreactivity of aging.

Aging and chronic inflammation are independent risk factors for the development of atherothrombosis and cardiovascular disease. We hypothesized that aging-associated inflammation promotes the development of platelet hyperreactivity and increases thrombotic risk during aging. Functional platelet studies in aged-frail adults and old mice demonstrated that their platelets are hyperreactive and form larger thrombi. We identified tumor necrosis factor α (TNF-α) as the key aging-associated proinflammatory cytokine responsible for platelet hyperreactivity. We further showed that platelet hyperreactivity is neutralized by abrogating signaling through TNF-α receptors in vivo in a mouse model of aging. Analysis of the bone marrow compartments showed significant platelet-biased hematopoiesis in old mice reflected by increased megakaryocyte-committed progenitor cells, megakaryocyte ploidy status, and thrombocytosis. Single-cell RNA-sequencing analysis of native mouse megakaryocytes showed significant reprogramming of inflammatory, metabolic, and mitochondrial gene pathways in old mice that appeared to play a significant role in determining platelet hyperreactivity. Platelets from old mice (where TNF-α was endogenously increased) and from young mice exposed to exogenous TNF-α exhibited significant mitochondrial changes characterized by elevated mitochondrial mass and increased oxygen consumption during activation. These mitochondrial changes were mitigated upon TNF-α blockade. Similar increases in platelet mitochondrial mass were seen in platelets from patients with myeloproliferative neoplasms, where TNF-α levels are also increased. Furthermore, metabolomics studies of platelets from young and old mice demonstrated age-dependent metabolic profiles that may differentially poise platelets for activation. Altogether, we present previously unrecognized evidence that TNF-α critically regulates megakaryocytes resident in the bone marrow niche and aging-associated platelet hyperreactivity and thrombosis.

Postoperative Changes in the Systemic Inflammatory Milieu in Older Surgical Patients.

Dysregulated inflammation is a central component of wound healing following surgery. We prospectively enrolled older patients (n = 25, age 65 ± 7 years) undergoing elective total knee arthroplasty or total hip arthroplasty secondary to advanced osteoarthritis (OA) and healthy controls (n = 48). Inflammatory, proangiogenic (vascular endothelial growth factor [VEGF], monocyte chemoattractant protein-1 [MCP-1], and interleukin-8 [IL-8]), and antiangiogenic (interferon γ [IFN-γ] and IL-4) factors were measured using a high-sensitivity biochip. Patients with OA had significantly higher baseline VEGF (10.5 ± 1.2 pg/mL vs 4.8 ± 0.2 pg/mL, P < .001), MCP-1 (130.6 ± 7.7 pg/mL vs 88.6 ± 3.9 pg/mL, P < .0001), and IL-8 (4.0 ± 0.5 pg/mL vs 2.6 ± 0.1 pg/mL, P < .05). Postoperatively, the levels of VEGF (10.5 ± 1.2 pg/mL vs 18.8 ± 1.5 pg/mL, P < .001) and MCP-1 (130.6 ± 7.7 pg/mL vs 153.1 ± 11.5 pg/mL, P < .05) increased significantly. Baseline and postoperative MCP-1 levels correlated positively and significantly with age. The levels of IFN-γ and IL-4 (which has anti-inflammatory properties) did not significantly differ at baseline in patients with OA compared to controls and did not significantly rise postoperatively. We conclude that systemic levels of pro-inflammatory and angiogenic proteins are increased in patients with OA and rise further postoperatively, while proteins that restrain inflammation and angiogenesis do not coordinately rise. These findings implicate imbalance in inflammatory pathways in OA that may contribute to its pathobiology.

Platelet-Monocyte Aggregates and C-Reactive Protein are Associated with VTE in Older Surgical Patients.

Emerging evidence implicates platelets as key mediators of venous thromboembolism (VTE). Nevertheless, the pathways by which platelets and circulating procoagulant proteins synergistically orchestrate VTE remain incompletely understood. We prospectively determined whether activated platelets and systemic procoagulant factors were associated with VTE in 32 older orthopedic surgery patients. Circulating platelet-monocyte aggregates (PMAs), p-selectin expression (P-SEL), and integrin αIIbß3 activation (PAC-1 binding) were assessed pre-operatively and 24 hours post-operatively. The proinflammatory and procoagulant molecule C-reactive protein (CRP), which induces PMA formation in vitro, along with plasma d-dimer and fibrinogen levels were also measured. The primary outcome was VTE occurring within 30 days post-operatively. Overall, 40.6% of patients developed VTE. Patients with VTE had a significant increase in circulating PMAs and CRP post-operatively, compared to those without VTE. Changes in PMA and CRP in VTE patients were significantly correlated (r(2) = 0.536, p = 0.004). In contrast, P-SEL expression and PAC-1 binding, fibrinogen levels, and d-dimers were not associated with VTE. This is the first study to identify that increased circulating PMAs and CRP levels are early markers associated with post-surgical VTE. Our findings also provide new clinical evidence supporting the interplay between PMAs and CRP in patients with VTE.

Prevalence of Anal Dysplasia in Patients With Inflammatory Bowel Disease.

BACKGROUND & AIMS: Although the prevalence of anal dysplasia is higher in some immunosuppressed populations, the prevalence in patients with inflammatory bowel disease (IBD) is unknown. We examined the prevalence of abnormal anal cytology among IBD patients, and its relation to the human papilloma virus (HPV). METHODS: Adults with IBD and age-matched healthy controls (HC) were recruited. IBD patients were categorized as nonimmunosuppressed (IBD-N) or immunosuppressed (IBD-I). Anal Papanicolaou tests were performed for HPV testing and classification by a cytopathologist as follows: negative, atypical squamous cells of undetermined significance (ASC-US), low-grade squamous intraepithelial lesion, high-grade squamous intraepithelial lesion, cancer, or unsatisfactory. RESULTS: A total of 270 subjects (100 IBD-I, 94 IBD-N, and 76 HC) were recruited. ASC-US were detected in 19 subjects, with a trend toward a higher prevalence among IBD subjects compared with HC (8.8% vs 2.6%; P = .10). The prevalence did not differ with respect to immunosuppression. Crohn's disease (CD) subjects had a higher prevalence of ASC-US compared with others with IBD (P = .02). Among those with CD, female sex and disease duration longer than 10 years were risk factors. There were no cases of low-grade squamous intraepithelial lesion, high-grade squamous intraepithelial lesion, or anal cancer in the cohort. HPV was present in 5.3% and 1.5% of subjects with and without ASC-US, respectively (P = .26). CONCLUSIONS: Although there was a trend toward abnormal anal Papanicolaou tests in IBD subjects compared with HC, there was no difference based on immunosuppression. The presence of HPV did not correlate with abnormal anal cytology. Risk factors associated with this increased trend include female CD subjects and those with a longer duration of CD. ClinicalTrials.gov number: NCT01860963; https://clinicaltrials.gov/ct2/show/NCT01860963.