Innate immunity and aging

Systemic Factors Affecting Human Beta-Defensins in Oral Cavity

Human beta-defensins are host defense peptides with broad antimicrobial and inflammatory functions. In the oral cavity, these peptides are produced mainly by the keratinocytes of the epithelium; however, fibroblasts, monocytes, and macrophages also contribute to oral human beta-defensin expressions. The resident and immune cells of the oral cavity come into contact with various microbe-associated molecular patterns continuously and simultaneously. The overall antimicrobial cellular response is highly influenced by local and environmental factors. Recent studies have produced evidence showing that not only systemic chronic diseases but also systemic factors like hyperglycemia, pregnancy, the long-term use of certain vitamins, and aging can modulate oral cellular antimicrobial responses against microbial challenges. Therefore, the aim of this narrative review is to discuss the role of systemic factors on oral human beta-defensin expressions.

Impact of age on the host response to sepsis in a murine model of fecal-induced peritonitis

INTRODUCTION

Despite older adults being more vulnerable to sepsis, most preclinical research on sepsis has been conducted using young animals. This results in decreased scientific validity since age is an independent predictor of poor outcome. In this study, we explored the impact of aging on the host response to sepsis using the fecal-induced peritonitis (FIP) model developed by the National Preclinical Sepsis Platform (NPSP).

METHODS

C57BL/6 mice (3 or 12 months old) were injected intraperitoneally with rat fecal slurry (0.75 mg/g) or a control vehicle. To investigate the early stage of sepsis, mice were culled at 4 h, 8 h, or 12 h to investigate disease severity, immunothrombosis biomarkers, and organ injury. Mice received buprenorphine at 4 h post-FIP. A separate cohort of FIP mice were studied for 72 h (with buprenorphine given at 4 h, 12 h, and then every 12 h post-FIP and antibiotics/fluids starting at 12 h post-FIP). Organs were harvested, plasma levels of Interleukin (IL)-6, IL-10, monocyte chemoattract protein (MCP-1)/CCL2, thrombin-antithrombin (TAT) complexes, cell-free DNA (CFDNA), and ADAMTS13 activity were quantified, and bacterial loads were measured.

RESULTS

In the 12 h time course study, aged FIP mice demonstrated increased inflammation and injury to the lungs compared to young FIP mice. In the 72 h study, aged FIP mice exhibited a higher mortality rate (89%) compared to young FIP mice (42%) (p < 0.001). Aged FIP non-survivors also exhibited a trend towards elevated IL-6, TAT, CFDNA, CCL2, and decreased IL-10, and impaired bacterial clearance compared to young FIP non-survivors.

CONCLUSION

To our knowledge, this is the first study to investigate the impact of age on survival using the FIP model of sepsis. Our model includes clinically-relevant supportive therapies and inclusion of both sexes. The higher mortality rate in aged mice may reflect increased inflammation and worsened organ injury in the early stage of sepsis. We also observed trends in impaired bacterial clearance, increase in IL-6, TAT, CFDNA, CCL2, and decreased IL-10 and ADAMTS13 activity in aged septic non-survivors compared to young septic non-survivors. Our aging model may help to increase the scientific validity of preclinical research and may be useful for identifying mechanisms of age-related susceptibility to sepsis as well as age-specific treatment strategies.

Risk factors for serious infections in inpatients with systemic lupus erythematosus

OBJECTIVES

To investigate the risk factors for serious infections among hospitalized systemic lupus erythematosus (SLE) patients, and to provide the advice for preventing serious infections in SLE patients.

METHODS

Information of SLE patients hospitalized from March 2017 to February 2019 at the Department of Rheumatology and Immunology, Xiangya Hospital, Central South University was obtained. The patients were assigned into a serious infection group and a non-serious infection group. The risk factors for serious infections among SLE inpatients were identified by comparison between the 2 groups and multivariate logistic regression analysis.

RESULTS

There were 463 SLE inpatients in total, and 144 were in the serious infection group and 319 in the non-serious infection group. Multivariate logistic regression analysis showed that age ≥54.50 years old (OR=4.958, P<0.001), cardiovascular involvement (OR=6.287, P<0.001), hematologic involvement (OR=2.643, P=0.003), serum albumin <20 g/L (OR=2.340, P=0.036), C-reaction protein (CRP)/erythrocyte sedimentation rate (ESR)≥0.12 (OR=2.430, P=0.002), glucocorticoid dose ≥8.75 mg/d prednisone-equivalent (OR=2.465, P=0.002), and the combined use of immunosuppressive agents (OR=2.847, P=0.037) were the risk factors for serious infections in SLE inpatients.

CONCLUSIONS

SLE patients with older age, cardiovascular involvement, hematologic involvement, low serum albumin are prone to suffering serious infections. Increased CRP/ESR ratio indicates serious infections in SLE inpatients. High-dose glucocorticoid and the combined use of immunosuppressive agents can increase the risk of serious infections in SLE inpatients.

Effect of Age on Bleeding on Probing (BOP) as an Indicator of Periodontal Inflammation in Patients Enrolled in Supportive Periodontal Therapy

PURPOSE

To assess the effect of age on the mean percentage of bleeding on probing (BOP) during supportive periodontal therapy (SPT) in patients enrolled in SPT for at least 5 years. Materials and Methods: This study was performed as a retrospective analysis of data collected from SPT patients initially diagnosed with gingivitis or mild to severe periodontitis. Two groups of patients were selected: in group A, younger adults (age ≤ 35 years) were included while group B consisted of older SPT patients (age ≥ 65 years). BOP in the two groups was compared according to both disease severity and % compliance with SPT visits. Results: BOP in all patients (n = 236) was 19.2% (± 12.4). Group A (n = 110) presented mean BOP levels of 19.7% (± 11.8), while lower BOP levels of 18.7% (± 13.0) were found in group B (n = 126; p = 0.5272). Older patients demonstrating high % compliance had lower mean BOP levels (14.2% ± 9.5) than younger patients (18.0% ±  11.7; p = 0.0841). Similarly, BOP was lower in older patients with moderate (group B: 18.4% ± 12.1, group A: 19.3% ± 14.6, p = 0.0541) or severe periodontitis (group B: 22.4% ± 11.4, group A: 23.2% ±  14.0; p = 0.3440). In patients with moderate or severe periodontitis and higher % compliance with SPT, the mean BOP was statistically significantly lower in older patients than in younger patients (moderate: 14.4% ± 11.9 vs 19.4% ± 15.1, p < 0.0001; severe: 13.2% ± 11.1 vs 18.3% ± 17.5, p = 0.0170). Conclusion: Older patients enrolled in SPT may present lower levels of BOP. This finding should be considered when determining SPT intervals with elderly patients.

Evidence for possible association of vitamin D status with cytokine storm and unregulated inflammation in COVID-19 patients

OBJECTIVES

We present evidence for a possible role of Vitamin D (VitD) deficiency in unregulated cytokine production and inflammation leading to complications in COVID-19 patients.

DESIGN

The time-adjusted case mortality ratio (T-CMR) was estimated as the ratio of deceased patients on day N to the confirmed cases on day N-8. The adaptive average of T-CMR (A-CMR) was calculated as a metric of COVID-19 associated mortality. A model based on positivity change (PC) and an estimated prevalence of COVID-19 was used to determine countries with similar screening strategies. A possible association of A-CMR with the mean concentration of 25-hydroxyvitamin D (25(OH)D) in elderly individuals in countries with similar screening strategy was investigated. We considered high C-reactive protein (CRP) in severe COVID-19 patients (CRP ≥ 1 mg/dL) as a surrogate of a cytokine storm. We considered high-sensitivity CRP (hs-CRP) in healthy subjects as hs-CRP ≥ 0.2 mg/dL.

RESULTS

A link between 25(OH)D and A-CMR in countries with similar screening strategy is evidence for VitD's possible role in reducing unregulated cytokine production and inflammation among patients with severe COVID-19. We observed an odds ratio (OR) of 1.8 with 95% confidence interval (95% CI) (1.2 to 2.6) and an OR of 1.9 with 95% CI (1.4 to 2.7) for hs-CRP in VitD deficient elderly from low-income families and high-income families, respectively. COVID-19 patient-level data show an OR of 3.4 with 95% CI (2.15 to 5.4) for high CRP in severe COVID-19 patients.

CONCLUSION

We conclude that future studies on VitD's role in reducing cytokine storm and COVID-19 mortality are warranted.

Role of neutrophil-lymphocyte-ratio in the mortality of males diagnosed with COVID-19

BACKGROUND AND OBJECTIVES

With this study, for the first time among patients diagnosed with COVID-19, the neutrophil-lymphocyte-ratios of men and women were compared.

MATERIALS AND METHODS

The study was conducted with 80 patients and the data was gained retrospectively on the electronic documents of the hospital.

RESULTS

The neutrophil-lymphocyte-ratio was statistically significant and higher in the male than the women for all ages and geriatric patients (p<0.05).

CONCLUSION

The higher neutrophil-lymphocyte-ratio in older males diagnosed with COVID-19 could be a causative reason for the higher mortality rates in men. We hope that these findings would be helpful for further studies.

Age- and Sex-associated Differences in Phenotypic and Functional Characteristics of Peripheral Blood Lymphocytes in Chimpanzees (Pan troglodytes)

Chimpanzees are the closest phylogenetic relatives to humans, sharing more than 98% genetic sequence identity. These genetic similarities prompted the belief that chimpanzees can serve as an ideal model for human disease conditions and vaccine development. However, in light of the recent NIH decision to phase out biomedical research in chimpanzees and retire NIH-supported chimpanzees, data from the present study will continue to provide value for the care of aged and sick chimpanzees located in zoos, sanctuaries, and primate centers. Surprisingly little information has been published regarding the normal chimpanzee immune system, and most extant studies have been based on small numbers of animals. In the current study, we provide a better understanding of the chimpanzee immune system with regard to age and sex. We examined immune parameters of chimpanzees (n = 94; 51 female, 43 male; age, 6 to 47 y) by using flow cytometry, immune function analysis, and cytokine analysis. Because lymphocytes are key mediators of cellular immune responses, particularly to intracellular pathogens such as viruses, we surveyed the phenotypic and functional attributes of T and B lymphocytes in this healthy and age-stratified population of chimpanzees. We noted a significantly higher percentage of CD16+T cells in male compared with female chimpanzees but no significant changes in percentages of CD3+, CD4+, CD8+, or CD4+CD8+ T cells with age or sex. In addition, aging was associated with decreased proliferative responses to mitogens in both sexes. Sex-specific differences also were present in the percentage of NK cells but not in their cytotoxic activity and in circulating cytokine levels in plasma. Going forward, the data presented here regarding immune cell changes associated with aging in healthy chimpanzees will serve to enhance the care of geriatric and ill animals.

The role of nutrition in enhancing immunity in aging

Aging is associated with declined immune function, particularly T cell-mediated activity, which contributes to increased morbidity and mortality from infectious disease and cancer in the elderly. Studies have shown that nutritional intervention may be a promising approach to reversing impaired immune function and diminished resistance to infection with aging. However, controversy exists concerning every nutritional regimen tested to date. In this article, we will review the progress of research in this field with a focus on nutrition factor information that is relatively abundant in the literature. While vitamin E deficiency is rare, intake above recommended levels can enhance T cell function in aged animals and humans. This effect is believed to contribute toward increased resistance to influenza infection in animals and reduced incidence of upper respiratory infection in the elderly. Zinc deficiency, common in the elderly, is linked to impaired immune function and increased risk for acquiring infection, which can be rectified by zinc supplementation. However, higher than recommended upper limits of zinc may adversely affect immune function. Probiotics are increasingly being recognized as an effective, immune-modulating nutritional factor. However, to be effective, they require an adequate supplementation period; additionally, their effects are strain-specific and among certain strains, a synergistic effect is observed. Increased intake of fish or n-3 PUFA may be beneficial to inflammatory and autoimmune disorders as well as to several age-related diseases. Conversely, the immunosuppressive effect of fish oils on T cell-mediated function has raised concerns regarding their impact on resistance to infection. Caloric restriction (CR) is shown to delay immunosenescence in animals, but this effect needs to be verified in humans. Timing for CR initiation may be important to determine whether CR is effective or even beneficial at all. Recent studies have suggested that CR, which is effective at improving the immune response of unchallenged animals, might compromise the host's defense against pathogenic infection and result in higher morbidity and mortality. The studies published thus far describe a critical role for nutrition in maintaining the immune response of the aged, but they also indicate the need for a more in-depth, wholestic approach to determining the optimal nutritional strategies that would maintain a healthy immune system in the elderly and promote their resistance to infection and other immune-related diseases.