Immunosénescence et infections, mythe ou réalité ?

Relationships Between Age, Frailty, Length of Care Home Residence and Biomarkers of Immunity and Inflammation in Older Care Home Residents in the United Kingdom

Aging is associated with changes to the immune system, collectively termed immunosenescence and inflammageing. However, the relationships among age, frailty, and immune parameters in older people resident in care homes are not well described. We assessed immune and inflammatory parameters in 184 United Kingdom care home residents aged over 65 years and how they relate to age, frailty index, and length of care home residence. Linear regression was used to identify the independent contribution of age, frailty, and length of care home residence to the various immune parameters as dependent variables. Participants had a mean age (±SD) of 85.3 ± 7.5 years, had been residing in the care home for a mean (±SD) of 1.9 ± 2.2 years at the time of study commencement, and 40.7% were severely frail. Length of care home residence and frailty index were correlated but age and frailty index and age and length of care home residence were not significantly correlated. All components of the full blood count, apart from total lymphocytes, were within the reference range; 31% of participants had blood lymphocyte numbers below the lower value of the reference range. Among the components of the full blood count, platelet numbers were positively associated with frailty index. Amongst plasma inflammatory markers, C-reactive protein (CRP), interleukin-1 receptor antagonist (IL-1ra), soluble E-selectin and interferon gamma-induced protein 10 (IP-10) were positively associated with frailty. Plasma soluble vascular cell adhesion molecule 1 (sVCAM-1), IP-10 and tumor necrosis factor receptor II (TNFRII) were positively associated with age. Plasma monocyte chemoattractant protein 1 was positively associated with length of care home residence. Frailty was an independent predictor of platelet numbers, plasma CRP, IL-1ra, IP-10, and sE-selectin. Age was an independent predictor of activated monocytes and plasma IP-10, TNFRII and sVCAM-1. Length of care home residence was an independent predictor of plasma MCP-1. This study concludes that there are independent links between increased frailty and inflammation and between increased age and inflammation amongst older people resident in care homes in the United Kingdom. Since, inflammation is known to contribute to morbidity and mortality in older people, the causes and consequences of inflammation in this population should be further explored.

[Undernutrition of the elderly]

Malnutrition remains a particularly important issue in elderly. Physiological ageing induces many changes but ageing cannot entirely explain a Protein-Energy Malnutrition (PEM). Nutritionnal screening is indicated once a year in community medicine or in the first 48hours in case of an acute disease or of hospitalization. The Mini Nutritional Assessment is recommended for screening and for the diagnostic of malnutrition. Possible aetiologies are large and must be investigated in order to be careful not to dismiss curable disease and to be able to take corrective actions. PEM is associated to functional decline, length of stay in hospital and to morbi-mortality. Recommendations for dietary intakes in healthy old subjects are about 30 kcal/kg/day and 1 g/kg/day of protein and are strongly enhanced in case of acute or chronic diseases. The nutritional strategy depends on spontaneous food intake, medical situation, patient profile and opinion. Appropriate nutritional care could reduce morbidity-mortality and prevent functional decline in various disease contexts.

Cytomegalovirus colitis mimicking rectal carcinoma in an immunocompetent elderly woman

Cytomegalovirus (CMV) colitis is uncommon in immunocompetent patients, despite a high seroprevalence rate of CMV in the general population. CMV infection has been described in individuals with compromised immune systems: in AIDS, under corticosteroid and immune modulating treatment, with cancer or haematological malignancies. Its most frequent clinical presentation is a necrotising ulcerative form; pseudotumoural CMV colitis has been described as highly exceptional. We report a case of CMV colitis mimicking rectal carcinoma in an immunocompetent elderly woman. The immunosenescence and protein-energy malnutrition increase incidence and severity of infectious diseases in elderly individuals. Immunosenescence may affect all aspects of immunity; severe protein malnutrition modifies mostly cellular immunity, growing susceptibility to infections.

Symptomatic cytomegalovirus gastrointestinal infection with positive quantitative real-time PCR findings in apparently immunocompetent patients: a case series

Cytomegalovirus (CMV) gastrointestinal disease rarely occurs in immunocompetent patients, and is mainly diagnosed on the basis of histopathological findings. Real-time PCR for CMV DNA quantification is considered to be a useful diagnostic tool, but its place in the diagnostic strategy is not clearly defined. The goal of the study was to describe the clinical and paraclinical features of apparently immunocompetent patients with CMV gastrointestinal disease diagnosed according to quantitative PCR results. In this retrospective study conducted in a 1500-bed tertiary-care centre, we reviewed the case records of apparently immunocompetent patients with positive findings of CMV DNA in gastrointestinal biopsies with compatible symptoms and endoscopic findings. A total of 13 patients were included between January 2007 and December 2010. The median age was 81 years, and 54% of patients had underlying immune-modulating conditions. Diarrhoea, haematochezia and dysphagia were the main reported symptoms, and ulcers were the main endoscopic findings. The mean value of CMV DNA load in gastrointestinal biopsies was 3845 copies/μg total DNA (range, 15-15 500 copies/μg total DNA). The highest values were found in two patients who were diagnosed with adenocarcinoma in the subsequent course of CMV infection. Clinical features were similar to those in previous series in which diagnosis was based on histopathological analysis. Elderly people are more commonly affected, and a link with immune senescence is possible. Quantification of CMV DNA seems to be a useful tool for diagnosis when combined with clinical and endoscopic findings, but further studies are necessary to interpret quantitative values.

Uveitis in the Aging Eye: Incidence, Patterns, and Differential Diagnosis

Uveitis is a vision threatening inflammation of the eye that carries considerable morbidity. It is responsible for 10% of legal blindness in the United States and up to 25% in the developing world. Uveitis in patients more than 60 years of age is less common. The aging body has a changing response of the immune system, which might reflect a different pattern of uveitis in the elderly population. In this paper we review the incidence and patterns of uveitis in the elderly as reported in the literature and discuss changes with time. We also delineate a thorough differential diagnosis of de novo uveitis in the elderly.

Diagnostic criteria for urinary tract infection in hospitalized elderly patients over 75 years of age: a multicenter cross-sectional study

INTRODUCTION

Urinary tract infection (UTI) is one of the most frequent infections in geriatric patients. Nevertheless, the diagnosis remains difficult because of the high prevalence of asymptomatic bacteriuria (AB). We studied the diagnosis criteria used by physicians in geriatric patients 75 years of age or more.

METHOD

A multicenter study was carried out in October 2009 in acute care wards (geriatrics, infectious diseases, internal medicine). During 1 week, the local investigator collected all positive urine microscopy and culture in geriatric patients 75 years of age or more and filled out a questionnaire on the final diagnosis (AB, cystitis, pyelonephritis, prostatitis), symptoms, clinical signs, and other infectious diagnosis.

RESULTS

Two hundred and forty-one questionnaires were filled out in 48 wards. Physicians diagnosed AB in 91 patients (37.8%), cystitis in 72 (29.9%), pyelonephritis in 48 (19.9%), prostatitis in 20 (8.3%). 28.2% of patients were asymptomatic; 35% presented with clinical signs. General signs were significantly associated with invasive infection and the absence of functional signs with AB. Among the patients presenting with an invasive UTI, 27.9% also presented with another infection. This other infection was not statistically associated with AB, cystitis, or invasive UTI.

CONCLUSION

Too many urine microscopy and culture procedures are not justified, and too many patients are diagnosed with several infections. Usual functional and clinical signs are important for the diagnosis but are infrequent. It seems necessary to review the range of clinical presentations and diagnostic criteria for UTI in geriatric patients.

Innate immunosenescence: effect of aging on cells and receptors of the innate immune system in humans

Components of the innate immune response, including neutrophils and macrophages, are the first line of defense against infections. Their role is to initiate an inflammatory response, phagocyte and kill pathogens, recruit natural killer cells (NK), and facilitate the maturation and migration of dendritic cells that will initiate the adaptive immune response. Extraordinary advances have been made in the last decade on the knowledge of the receptors and mechanisms used by cells of the innate immunity not only to sense and eliminate the pathogen but also to communicate each other and collaborate with cells of adaptive immunity to mount an effective immune response. The analysis of innate immunity in elderly humans has evidenced that aging has a profound impact on the phenotype and functions of these cells. Thus altered expression and/or function of innate immunity receptors and signal transduction leading to defective activation and decreased chemotaxis, phagocytosis and intracellular killing of pathogens have been described. The phenotype and function of NK cells from elderly individuals show significant changes that are compatible with remodeling of the different NK subsets, with a decrease in the CD56bright subpopulation and accumulation of the CD56dim cells, in particular those differentiated NK cells that co-express CD57, as well as a decreased expression of activating natural cytotoxicity receptors. These alterations can be responsible of the decreased production of cytokines and the lower per-cell cytotoxicity observed in the elderly. Considering the relevance of these cells in the initiation of the immune response, the possibility to reactivate the function of innate immune cells should be considered in order to improve the response to pathogens and to vaccination in the elderly.

Seroepidemiology of Toxoplasma gondii infection in elderly people in a northern Mexican city

Whereas it is well-known that the seroprevalence of infection with Toxoplasma gondii increases with age, details of the seroepidemiology of infection in elderly people are largely unknown. Anti-T. gondii IgG and IgM antibody levels were determined in 483 subjects aged ≥60 years old in Durango City, Mexico, using enzyme-linked immunosorbent assays. Socio-demographic, clinical, and behavioral characteristics from each participant were also obtained. In total, 58 (12%) of 483 participants (mean age 70.35±6.63 years) had anti-T. gondii IgG antibodies, and 14 (2.9%) also had anti-T. gondii IgM antibodies. Seroprevalence of infection varied significantly with age, birthplace, and educational level. Seroprevalence increased with age, especially in women (p=0.01), and was higher in subjects born outside of Durango State than those born within Durango State (p=0.008). Seroprevalence was higher in men with up to 12 years of education than in men with more than 12 years of education (p=0.01). Multivariate analysis of behavioral data showed a positive association of T. gondii infection with the presence of cats in the neighborhood, as well as consumption of boar, pigeon, iguana, and armadillo meats, and chorizo. Gender-specific analysis showed the described associations in women but not in men. In contrast, consumption of beef showed a negative association with T. gondii infection. This is the first report of the seroprevalence and contributing factors for T. gondii infection in elderly people, and of an association of the consumption of armadillo and iguana meats with T. gondii infection. Our results will provide the basis for the design of optimal preventive measures against T. gondii infection.

Human microbial ecology: lactobacilli, probiotics, selective decontamination

Health care-associated infections are closely associated with different medical interventions which interrupt the balance of human microbiota. The occasional predominance of opportunistic pathogens may lead to their translocation into the lymph nodes and bloodstream, causing endogenous (primary or secondary) hospital infections. The question is raised as to if there is a possibility for prevention of the imbalance of GI microbiota during medical interventions in critically ill patients. Prophylactic selective decontamination of the digestive tract (SDD) simultaneously applies three to four different antimicrobials for the suppression of enteric aerobic microbes, which are potentially pathogenic microorganisms. However, there is no convincing evidence that the indigenous beneficial intestinal microbiota are preserved, resulting in reduced mortality of high-risk patients. In this overview, we have evaluated the antimicrobial treatment guidelines of the Infectious Diseases Society of America (IDSA) for intra-abdominal infections in adults and seniors according to their safety for different Lactobacillus spp. The data from our group and in the literature have shown that all tested lactobacilli strains (nearly one hundred) were insusceptible to metronidazole while different species of lactobacilli of the three fermentation groups expressed particular antibiotic susceptibility to vancomycin, cefoxitin, ciprofloxacin and some new tetracyclines. We have relied on microbial ecology data showing that the GI tracts of adults and the elderly are simultaneously colonised at least with several (four to a maximum of 12) Lactobacillus species expressing variable intrinsic insusceptibility to the aforementioned antimicrobials, according to the provided data in table. This finding offers the possibility of preserving the colonisation of the intestine with some beneficial lactobacilli during antimicrobial treatment in critically ill patients with health care-associated infections. Several probiotic Lactobacillus spp. strains are intrinsically resistant to antimicrobials and can be used during antibacterial therapy, however, their application as an additive to antimicrobial treatment in critically ill patients needs to be investigated in well-designed clinical trials.

Factors that may impact on immunosenescence: an appraisal

The increasing ratio of ageing population poses new challenges to healthcare systems. The elderly frequently suffer from severe infections. Vaccination could protect them against several infectious diseases, but it can be effective only if cells that are capable of responding are still present in the repertoire. Recent vaccination strategies in the elderly might achieve low effectiveness due to age-related immune impairment. Immunosenescence affects both the innate and adaptive immunity.Beside individual variations of genetic predisposition, epigenetic changes over the full course of human life exert immunomodulating effects. Disturbances in macrophage-derived cytokine release and reduction of the natural killer cell mediated cytotoxicity lead to increased frequency of infections. Ageing dampens the ability of B cells to produce antibodies against novel antigens. Exhausted memory B lymphocyte subsets replace naïve cells. Decline of cell-mediated immunity is the consequence of multiple changes, including thymic atrophy, reduced output of new T lymphocytes, accumulation of anergic memory cells, and deficiencies in cytokines production. Persistent viral and parasitic infections contribute to the loss of immunosurveillance and premature exhaustion of T cells. Reduced telomerase activity and Toll-like receptor expression can be improved by chemotherapy. Reversion of thymic atrophy could be achieved by thymus transplantation, depletion of accumulated dysfunctional naive T cells and herpesvirus-specific exhausted memory cells. Administration of interleukin (IL)-2, IL-7, IL-10, keratinocyte growth factor, thymic stromal lymphopoietin, as well as leptin and growth hormone boost thymopoiesis. In animals, several strategies have been explored to produce superior vaccines. Among them, virosomal vaccines containing polypeptide antigens or DNA plasmids as well as new adjuvanted vaccine formulations elicit higher dendritic cell activity and more effective serologic than conventional vaccines responses in the elderly. Hopefully, at least some of these approaches can be translated to human medicine in a not too far future.