Helminth-Induced and Th2-Dependent Alterations of the Gut Microbiota Attenuate Obesity Caused by High-Fat Diet

BACKGROUND & AIMS

Epidemiological and animal studies have indicated an inverse correlation between the rising prevalence of obesity and metabolic syndrome and exposure to helminths. Whether helminth-induced immune response contributes to microbiota remodeling in obesity remains unknown. The aim of this study is to explore the immune-regulatory role of helminth in the prevention of HFD-induced obesity through remodeling gut microbiome.

METHODS

C57BL/6J WT and STAT6-/- mice were infected with Heligmosomoides polygyrus and followed by high fat diet (HFD) feeding for 6 weeks. The host immune response, body weight, and fecal microbiota composition were analyzed. We used adoptive transfer of M2 macrophages and microbiota transplantation approaches to determine the impact of these factors on HFD-obesity. We also examined stool microbiota composition and short chain fatty acids (SCFAs) concentration and determined the expression of SCFA-relevant receptors in the recipient mice.

RESULTS

Helminth infection of STAT6-/- (Th2-deficient) mice and adoptive transfer of helminth-induced alternatively activated (M2) macrophages demonstrated that the helminth-associated Th2 immune response plays an important role in the protection against obesity and induces changes in microbiota composition. Microbiota transplantation showed that helminth-induced, Th2-dependent alterations of the gut microbiota are sufficient to confer protection against obesity. Collectively, these results indicate that helminth infection protects against HFD-induced obesity by Th2-dependent, M2 macrophage-mediated alterations of the intestinal microbiota.

CONCLUSION

Our findings provide new mechanistic insights into the complex interplay between helminth infection, the immune system and the gut microbiota in a HFD-induced obesity model and holds promise for gut microbiome-targeted immunotherapy in obesity prevention.

Helminth infection protects against high fat diet-induced obesity via induction of alternatively activated macrophages

Epidemiological studies indicate an inverse correlation between the prevalence of the so-called western diseases, such as obesity and metabolic syndrome, and the exposure to helminths. Obesity, a key risk factor for many chronic health problems, is rising globally and is accompanied by low-grade inflammation in adipose tissues. The precise mechanism by which helminths modulate metabolic syndrome and obesity is not fully understood. We infected high fat diet (HFD)-induced obese mice with the intestinal nematode parasite Heligmosomoides polygyrus and observed that helminth infection resulted in significantly attenuated obesity. Attenuated obesity corresponded with marked upregulation of uncoupling protein 1 (UCP1), a key protein involved in energy expenditure, in adipose tissue, suppression of glucose and triglyceride levels, and alteration in the expression of key genes involved in lipid metabolism. Moreover, the attenuated obesity in infected mice was associated with enhanced helminth-induced Th2/Treg responses and M2 macrophage polarization. Adoptive transfer of helminth-stimulated M2 cells to mice that were not infected with H. polygyrus resulted in a significant amelioration of HFD-induced obesity and increased adipose tissue browning. Thus, our results provide evidence that the helminth-dependent protection against obesity involves the induction of M2 macrophages.

Frostbite of the upper extremity

Human capacity for physiologic adaptation to cold is minimal; we survive by insulating ourselves with protective clothing. In addition to the irreversible direct injury caused by ice crystallization, the authors have outlined four possible mechanisms by which indirect injury may damage tissue. Other than rapid rewarming, there is no uniformly accepted protocol for the treatment of frostbite injury. Attempting to sort out the world's literature on frostbite in an effort to present a comprehensive treatment protocol is a daunting task. In addition to the probably irreversible direct injury caused by ice crystallization, the authors have outlined at least four possible mechanisms by which indirect injury may damage tissue. The literature is full of various treatment protocols that allegedly are beneficial despite addressing different mechanisms. Mills described 10 different categories of medications, each addressing one of four possible mechanisms, used in the clinical treatment of frostbite injury over a 30-year period. Analyzing this information is even more confusing when one realizes that there is little uniformity in animal models employed to generate these data. This is further complicated by the lack of clinical correlation with the most common experimental model--liquid nitrogen rapid freezing. The risk of frostbite is highest when psychiatric disturbance, intoxication, or unplanned circumstances lead to cold exposure without adequate protective clothing. As tissue freezes, both direct and indirect factors cause injury. Most therapies have been aimed at limiting indirect injury, in an attempt to limit progressive tissue loss. Rapid rewarming is universally accepted, but the benefits of other modalities are still controversial. Traditionally, observation and delayed amputation have been employed to manage frostbite. More recently, triple-phase bone scans have been used to distinguish between tissue that is irreversibly destined for necrosis and tissue that is at-risk for necrosis, but potentially salvageable. Early operation can be used to provide at-risk tissue with a new blood supply and preserve both function and length in the upper extremity.

The 5' untranslated regions of the rat A2A adenosine receptor gene function as negative translational regulators

The rat A2A adenosine receptor (A2A-R) gene contains two promoters, P1 and P2, which produce transcript 1 and transcript 2, respectively. These transcripts differ in the lengths of their 5' untranslated regions (5'UTR1: 514 bp, initiated from P1; 5'UTR2: 221 bp, initiated from P2) but encode the same protein. In the present study, we demonstrate that transcript 2 is present in various tissues at different levels, whereas transcript 1 is found only in the striatum. In the striatum, the level of transcript 2 is approximately 300-fold higher than that of transcript 1. The 5'UTR of both transcripts suppresses the expression of A2A-R and a firefly luciferase reporter gene at the translational level; this suppression is not observed after mutational inactivation of an "out-of-frame" upstream AUG codon. Translational suppression by the 5'UTR was also confirmed in cells using a bicistronic strategy. Collectively, these data suggest that P2 is the major promoter of the rat A2A-R gene. The 5'UTR of the rat A2A-R gene exerts an inhibitory effect on translation by an upstream open reading frame. Because the 5'UTR of the A2A-R gene possesses strong interspecies homology, translational suppression may be a general mechanism by which the expression of the A2A-R gene is regulated.

The problem scar

Through deeper understanding of the physiology of wound healing and physico-chemical principles of scarring, biomedical science facilitates the development of new strategies in treatment and prevention of problem scars. It is important for practicing physicians and surgeons to be better aware of the full range of available techniques to control scar formation, and for any medical intervention to be planned in such a way that potential problems are apprehended and minimized or avoided. This article describes the clinical applications of recent research in scar control in order to provide such guidance.

Prediction of adverse perinatal outcome by maternal serum screening for Down syndrome in an Asian population

OBJECTIVE

To investigate the association between adverse perinatal outcomes and abnormal elevations of serum marker levels (alpha-fetoprotein [AFP] and free beta-hCG) or a false-positive screen for Down syndrome.

METHODS

Pregnancy outcome information was available for 5885 Taiwanese women under 35 years of age who had second-trimester maternal serum screening for Down syndrome, using AFP and free beta-hCG, and delivered a chromosomally normal fetus. Those with AFP at least 2.0 multiples of the median (MoM), free beta-hCG at least 2.5 MoM, or a false-positive screen (risk ratio at least 1:270) were identified, and the risk for adverse perinatal outcome was assessed.

RESULTS

A serum AFP level at least 2.0 MoM (n = 176, 3.0%) was significantly associated with the occurrence of preterm delivery, low Apgar scores, small-for-gestational-age infants, low birth weight or very low birth weight, fetal death, premature rupture of membranes, oligohydramnios, and a higher incidence of perinatal mortality. A serum free beta-hCG level at least 2.5 MoM (n = 416, 7.1%) was significantly associated with low birth weight, an abnormally adherent placenta, and the occurrence of meconium-stained amniotic fluid. A higher incidence of fetal structural anomalies other than neural tube or abdominal wall defects, large-for-gestational-age infants, and postpartum hemorrhage was observed for a calculated risk of at least 1:270 (n = 311, 5.3%) independent of the other biochemical markers.

CONCLUSION

Asian women with unexplained elevations of serum AFP or free beta-hCG, or a false-positive screen for Down syndrome are at increased risk for various adverse perinatal outcomes. Careful fetal ultrasound examination and thoughtful strategy for perinatal management are warranted for these patients.

Silicone implants and the inhibition of cancer

The safety of augmentation mammaplasty and its relationship to breast cancer has been a much debated topic. The authors previously showed a decreased incidence of breast cancer in rats who had received silicone implants 2 weeks before carcinogen stimulation. The present study was designed to determine (1) whether this protective effect is influenced by the location of the implant, and (2) whether tumor incidence could also be altered in spontaneous mammary tumor-forming animals, the C3H/OuJ mice. (1) A total of 110 rats received either a silicone implant or a sham operation in one of three locations: inframammary region, dorsum, or intraperitoneal cavity. Methylnitrosoured (MNU) injections occurred 14 days after implantation. Animals were examined weekly for tumor growth and were killed 250 days after MNU injection. Animals with silicone implants beneath the mammary gland had a statistically significant lower incidence of breast cancer formation (11.5 percent) compared with both dorsally implanted animals (45.8 percent) and sham controls (64 percent). (2) Sixty C3H/OuJ mice underwent implantation of either a silicone implant, free silicone gel, silicone sheet, or a sham operation. At 50 weeks of age, after weekly examinations, the animals were killed. The cancer incidence in mice with silicone implants was 17 percent compared with 50 percent found in sham controls. Exposure to a silicone prosthesis at an early age does not seem to increase tumor incidence and may even have a locally protective effect against breast cancer formation.