Alterations in Monocyte Phenotypes and Functions after a Hip Fracture in Elderly Individuals: A 6-Month Longitudinal Study.

BACKGROUND: Healthy elderly individuals are particularly prone to catastrophic events at any moment of their lives. One stressful event for individuals aged 65 and older is a fall that results in a fracture of the hip (HF). HF causes a state of inflammation that may affect immune responses. In this connection, we have reported that HF induced alterations in neutrophil functions. OBJECTIVE: To assess the impact of HF on classical (cM), intermediate (iM) and non-classical (ncM) monocyte subsets. METHODS: Distribution, functions (chemotaxis, phagocytosis, superoxide production and cytokine production), phenotype and activation (NF-x03BA;B and PI3K) were evaluated in monocyte subsets before surgery and 6 weeks and 6 months after the event. RESULTS: The distribution of cM and ncM was unchanged, but iM transiently increased before surgery. Sustained increases (iM response to CCL2 and CX3CL1) and decreases (cM and ncM response to CCL2) in chemotaxis were observed. Phagocytosis and superoxide production were impaired in cM but not in iM or ncM. Sustained expression of HLA-DR occurred in cM but not in iM and ncM. Sustained decreased expression of CD11b occurred only in ncM. Sustained decreases (cM and ncM) and increases (iM) in CCR2 expression were observed. An elevated expression of CX3CR1 was found only in iM. cM produced elevated quantities of TNFα. There was a transient oxidative burst of production before surgery in iM and a sustained decrease in ncM. IL-10 production was severely impaired in cM and decreased in iM prior to surgery. Sustained activation (cM), inhibition (ncM) and transient activation (iM) of NF-x03BA;B were observed. Activation of PI3K was severely impaired in cM and ncM but was sustained in iM. CONCLUSION: HF had more impact on cM and ncM functions than on iM. HF triggered a switch in cM functions from phagocytic to inflammatory elevated TNFα-producing cells. These changes may impact clinical outcomes of HF with respect to inflammation, opportunistic infections and physical recovery.

Predictors of the antibody response to influenza vaccination in older adults with type 2 diabetes.

OBJECTIVE: Type 2 diabetes mellitus (T2DM) is one of the most prevalent chronic inflammatory diseases of the elderly. Its development is related to the alteration of the immune system with aging characterized by immunosenescence and inflamm-aging. In turn, T2DM also alters the immune response. As a consequence, older people with T2DM are more susceptible to influenza and to its complications as compared with healthy controls. Vaccination against influenza has shown poor efficacy in the older population and even less efficacy in patients with diabetes. We studied here the antibody response to vaccination in healthy and diabetic elderly participants. RESEARCH DESIGN AND METHODS: In 2 groups of elderly participants (healthy N=119 and T2DM N=102), we measured the immunogenicity of influenza vaccine by hemagglutination inhibition assays. We assessed several blood and functional parameters as potential predictors of the vaccine efficacy. RESULTS: We found no difference between antibody responses in diabetic elderly compared with healthy elderly. Among the biological and functional determinants, the cytomegalovirus (CMV) serostatus played a more prominent role in determining the magnitude of response. We concluded that in addition to age and diabetic status, immunological history such as CMV status should be taken into account. None of the other biological or functional parameters studied could be reliably linked to the vaccine antibody response in older adults who are not frail including those with well-controlled diabetes. CONCLUSIONS: Our data strongly suggest that influenza vaccine should be administered to elderly patients with T2DM; however, the immune determinants of the antibody response to influenza vaccination should be further investigated.

Frailty, Inflammation and Immunosenescence.

Frailty is a still-evolving concept of a complex phenomenon. There are several algorithms and strategies for assessing frailty syndrome, but currently, no universally accepted definition or measurement protocol has been determined. Consequently, the biological cause(s) of frailty are also poorly defined. Much circumstantial experimental data point to the dysregulation of several key physiological systems, including the neuroendocrine, musculoskeletal, metabolic and immune/inflammatory systems, resulting from alterations in functional reserves. Immune dysregulation and inflammation as causes of frailty have gained some support from the results of longitudinal studies, but a true causal relationship has not been established. This chapter will describe the immune/inflammatory alterations found in frailty and their putative causal relationships with this state.

Altered neutrophil functions in elderly patients during a 6-month follow-up period after a hip fracture.

BACKGROUND: Fracture of the hip (HF) is a significant cause of morbidity and mortality in elderly individuals. HF is an acute stress that triggers a state of inflammation which may affect immune responses and physical recovery. METHODS: Longitudinal study of the impact of HF on the functions of polymorphonuclear neutrophils (PMNs) in elderly subjects. Data were recorded prior to surgery, 6weeks and 6months later. RESULTS: PMN functions were severely impaired shortly after HF (chemotaxis, phagocytosis, superoxide production) but there was a time-related recovery of some PMN functions (chemotaxis, phagocytosis) over time, except in the case of superoxide production. Whereas FcγRII (CD32) expression remained unchanged, FcγRIII (CD16) increased from low values before surgery to levels of controls 6months post-surgery. This was also the case for the C5a complement receptor and CD11b. TLR2 and TLR4 expressions were unchanged. Cytokine and chemokine secretions by stimulated PMN were altered. TNFα and IL-10 secretions were increased following HF but IL-8 secretion was decreased. Impaired PMN functions prior to surgery were related to alterations in PI3K and NF-κB signaling pathways. Recovery of these functions paralleled increased PI3K activity, although superoxide production remained low. Sustained activation of the NF-κB pathway by TNFα has been reported to involve upregulation of IKKß kinase activity. Activated IKKß kinase inhibits ERK1/2 and results in concomitant downstream inhibition of NADPH oxidase complex which can account for sustained impaired production of ROS in HF patients. CONCLUSION: Our data showed that the stress caused by HF negatively affects initial PMN responses shortly after the event and that may negatively influence clinical outcomes such as resolving long-term inflammation and recovery, as well as explaining susceptibility to opportunistic infections.

Aging, immunosenescence and membrane rafts: the lipid connection.

The decreased efficiency of immune responses in older people is partly a consequence of alterations in T lymphocyte functions caused by modifications in the early events of signal transduction. Several alterations in the signaling pathways of T lymphocytes have been described in older humans and animals. A unifying cause could be modifications in the physicochemical properties of the plasma membrane resulting from changes in its lipid composition and the distribution and function of lipid rafts (LR). The latter serve to assemble the initial components of the signaling cascade. Accumulating data suggest that the function of plasma membrane LR is altered with aging; we hypothesize that this would significantly contribute to immune dysregulation. The role of aging and cholesterol in LR functions in T lymphocytes is reviewed and discussed here.