Body adipose content is independently associated with a higher risk of organ failure and nosocomial infection in the nonobese patient postinjury

Diet-induced obesity promotes infection by impairment of the innate antimicrobial defense function of dermal adipocyte progenitors

Infections are a major complication of obesity, but the mechanisms responsible for impaired defense against microbes are not well understood. Here, we found that adipocyte progenitors were lost from the dermis during diet-induced obesity (DIO) in humans and mice. The loss of adipogenic fibroblasts from mice resulted in less antimicrobial peptide production and greatly increased susceptibility to Staphylococcus aureus infection. The decrease in adipocyte progenitors in DIO mice was explained by expression of transforming growth factor-β (TGFβ) by mature adipocytes that then inhibited adipocyte progenitors and the production of cathelicidin in vitro. Administration of a TGFβ receptor inhibitor or a peroxisome proliferator-activated receptor-γ agonist reversed this inhibition in both cultured adipocyte progenitors and in mice and subsequently restored the capacity of obese mice to defend against S. aureus skin infection. Together, these results explain how obesity promotes dysfunction of the antimicrobial function of reactive dermal adipogenesis and identifies potential therapeutic targets to manage skin infection associated with obesity.

Impact of weight reduction on selected immune system response among Hepatitis C virus Saudi patients

Background

Recently, about 2.35% of the world populations are estimated to be chronically infected with hepatitis C virus (HCV). Previous cohort studies indicated that obesity increases risk of hepatic steatosis and fibrosis in non-diabetic patients with chronic hepatitis C infection due to diminished response to anti-viral therapy and as a result obesity is considered as an important factor in the progression of chronic HCV. However, there is a strong association between BMI and the human immune system among HCV patients.

Objective

This study aimed to examine effects of weight reduction program on selected immune parameters among HCV Saudi patients.

Material and methods

One-hundred obese Saudi patients with chronic HCV infection participated in this study, their age ranged from 50–58 years and their body mass index (BMI) ranged from 30–35 kg/m². All Subjects were included in two groups: The first group received weight reduction program in the form of treadmill aerobic exercises in addition to diet control whereas, the second group received no therapeutic intervention. Parameters of CD3, CD4 and CD8 were quantified; Leukocyte, differential counts and BMI were measured before and after 3 months, at the end of the study.

Results

The mean values of BMI, white blood cells, total neutrophil count, monocytes, CD3, CD4 and CD8 were significantly decreased in the training group as a result of weight loss program; however the results of the control group were not significant. Also, there were significant differences between both groups at the end of the study.

Conclusion

Weight loss modulates immune system parameters of patients with HCV.

Impact of Body Mass Index on the Outcomes of Open Reduction for Mandibular Fractures

PURPOSE

Little is known about the impact of body mass index (BMI) on the postoperative outcomes of open reduction for mandibular fractures. The aim of this study was to investigate the relationship between BMI and short-term outcomes of surgery for mandibular fractures.

MATERIALS AND METHODS

We searched the Japanese Diagnosis Procedure Combination database to identify patients who underwent open reduction for mandibular fractures from July 2010 to March 2013. BMI was divided into three groups: less than 18.5 kg/m(2) (underweight), 18.5 to 24.9 kg/m(2) (normal weight), and 25 kg/m(2) or greater (overweight). The outcomes included postoperative complication rates, duration of anesthesia, length of stay, and total costs. We analyzed the relationships between BMI and the outcomes by multivariable regression analyses.

RESULTS

We analyzed 309 patients who underwent open reduction for mandibular fractures during the study period. The group with a BMI of 25 kg/m(2) or greater had a significantly longer hospital stay (3.8 days; 95% confidence interval, 0.5 to 7.1 days, P = .03) than the group with a normal BMI. BMI was not significantly associated with duration of anesthesia, postoperative complication rates, or total costs.

CONCLUSIONS

Regarding open reduction for mandibular fractures, overweight status may be associated with a prolonged length of stay, but may have little impact on operating time, postoperative morbidity, or overall costs.

Obesity: impact of infections and response to vaccines

Obesity is a common condition that has rapidly increased in both the industrialised and developing world in recent decades. Obese individuals show increased risk factors for severe infections and significant immune system dysregulation that may impair the immune response to vaccines. The main aim of this paper was to review the current knowledge regarding the association between obesity and the risk and outcome of infections as well as immune response to vaccines. The results showed that obesity is a highly complex clinical condition in which the functions of several organ and body systems, including the immune system, are modified. However, only a small minority of the biological mechanisms that lead to reduced host defences have been elucidated. Relevant efforts for future research should focus on obese children, as the available data on this population are scarce compared with the adult population. Even if most vaccines are given in the first months of life when obesity is rare, some vaccines require booster doses at preschool age, and other vaccines, such as the influenza vaccine, are recommended yearly in the obese population, but it is not known whether response to vaccines of obese patients is impaired. The reduced immune response of obese patients to vaccination can be deleterious not only for the patient but also for the community.

Differences in resuscitation in morbidly obese burn patients may contribute to high mortality

The rising number of obese patients poses new challenges for burn care. These may include adjustments in calculations of burn size, resuscitation, ventilator wean, nutritional goals as well as challenges in mobilization. The authors have focused this observational study on resuscitation in the obese patient population in the first 48 hours after burn injury. Previous trauma studies suggest a prolonged time to reach end points of resuscitation in the obese compared to nonobese injured patients. The authors hypothesize that obese patients have worse outcomes after thermal injury and that differences in the response to resuscitation contribute to this disparity. The authors retrospectively analyzed data prospectively collected in a multicenter trial to compare resuscitation and outcomes in patients stratified by National Institutes of Health/World Health Organization body mass index (BMI) classification (BMI: normal weight, 18.5-24.9; overweight, 25-29.9, obese, 30-39.9; morbidly obese, ≥40). Because of the distribution of body habitus in the obese, total burn size was recalculated for all patients by using the method proposed by Neaman and compared with Lund-Browder estimates. The authors analyzed patients by BMI class for fluids administered and end points of resuscitation at 24 and 48 hours. Multivariate analysis was used to compare morbidity and mortality across BMI groups. The authors identified 296 adult patients with a mean TBSA of 41%. Patient and injury characteristics were similar across BMI categories. No significant differences were observed in burn size calculations by using Neaman vs Lund-Browder formulas. Although resuscitation volumes exceeded the predicted formula in all BMI categories, higher BMI was associated with less fluid administered per actual body weight (P = .001). Base deficit on admission was highest in the morbidly obese group at 24 and 48 hours. Furthermore, the morbidly obese patients did not correct their metabolic acidosis to the extent of their lower BMI counterparts (P values .04 and .03). Complications and morbidities across BMI groups were similar, although examination of organ failure scores indicated more severe organ dysfunction in the morbidly obese group. Compared with being normal weight, being morbidly obese was an independent risk factor for death (odds ratio = 10.1; confidence interval, 1.94-52.5; P = .006). Morbidly obese patients with severe burns tend to receive closer to predicted fluid resuscitation volumes for their actual weight. However, this patient group has persistent metabolic acidosis during the resuscitation phase and is at risk of developing more severe multiple organ failure. These factors may contribute to higher mortality risk in the morbidly obese burn patient.

Abdominal adiposity is the main determinant of the C-reactive response to injury in subjects undergoing inguinal hernia repair

Background

Obesity and serum C-reactive protein (CRP) (a sensitive marker of inflammatory activity) are associated with most chronic diseases. Abdominal adiposity along with age is the strongest determinant of baseline CRP levels in healthy subjects. The mechanism of the association of serum CRP with disease is uncertain. We hypothesized that baseline serum CRP is a marker of inflammatory responsiveness to injury and that abdominal adiposity is the main determinant of this responsiveness. We studied the effect of abdominal adiposity, age and other environmental risk factors for chronic disease on the CRP response to a standardised surgical insult, unilateral hernia repair to not only test this hypothesis but to inform the factors which must be taken into account when assessing systemic inflammatory responses to surgery.

Methods

102 male subjects aged 24-94 underwent unilateral hernia repair by a single operator. CRP was measured at 0, 6, 24 and 48 hrs. Response was defined as the peak CRP adjusted for baseline CRP.

Results

Age and waist:hip ratio (WHR) were associated both with basal CRP and CRP response with similar effect sizes after adjustment for a wide-range of covariates. The adjusted proportional difference in CRP response per 10% increase in WHR was 1.50 (1.17-1.91) p = 0.0014 and 1.15(1.00-1.31) p = 0.05 per decade increase in age. There was no evidence of important effects of other environmental cardiovascular risk factors on CRP response.

Conclusion

Waist:hip ratio and age need to be considered when studying the inflammatory response to surgery. The finding that age and waist:hip ratio influence baseline and post-operative CRP levels to a similar extent suggests that baseline CRP is a measure of inflammatory responsiveness to casual stimuli and that higher age and obesity modulate the generic excitability of the inflammatory system leading to both higher baseline CRP and higher CRP response to surgery. The mechanism for the association of baseline CRP and waist:hip ratio to chronic disease outcomes could be through this increase in inflammatory system excitability.

Obesity and the risk and outcome of infection

The interactions between obesity and infectious diseases have recently received increasing recognition as emerging data have indicated an association between obesity and poor outcome in pandemic H1N1 influenza infection. Obesity is an established risk factor for surgical-site infections, nosocomial infections, periodontitis and skin infections. Several studies indicate that acute pancreatitis is more severe in the obese. Data are controversial and limited as regards the association between obesity and the risk and outcome of community-acquired infections such as pneumonia, bacteremia and sepsis and obesity and the course of HIV infection. As the cause-effect relationship between obesity and infection remains obscure in many infectious diseases, further studies are warranted. The consequences of obesity may have substantial effects on the global burden of infectious diseases.