Effects of bariatric surgery on telomere length and T-cell aging

Mode of delivery predicts postpartum maternal leukocyte telomere length

BACKGROUND

Recent studies have suggested that pregnancy accelerates biologic aging, yet little is known about how biomarkers of aging are affected by events during the peripartum period. Given that immune shifts are known to occur following surgery, we explored the relation between mode of delivery and postpartum maternal leukocyte telomere length (LTL), a marker of biologic aging.

STUDY DESIGN

Postpartum maternal blood samples were obtained from a prospective cohort of term, singleton livebirths without hypertensive disorders or peripartum infections between 2012 and 2018. The primary outcome was postpartum LTLs from one blood sample drawn between postpartum week 1 and up to 6 months postpartum, measured from thawed frozen peripheral blood mononuclear cells using quantitative PCR in basepairs (bp). Multivariable linear regression models compared LTLs between vaginal versus cesarean births, adjusting for age, body mass index, and nulliparity as potential confounders. Analyses were conducted in two mutually exclusive groups: those with LTL measured postpartum week 1 and those measured up to 6 months postpartum. Secondarily, we compared multiomics by mode of delivery using machine-learning methods to evaluate whether other biologic changes occurred following cesarean. These included transcriptomics, metabolomics, microbiomics, immunomics, and proteomics (serum and plasma).

RESULTS

Of 67 included people, 50 (74.6 %) had vaginal and 17 (25.4 %) had cesarean births. LTLs were significantly shorter after cesarean in postpartum week 1 (5755.2 bp cesarean versus 6267.8 bp vaginal, p = 0.01) as well as in the later draws (5586.6 versus 5945.6 bp, p = 0.04). After adjusting for confounders, these differences persisted in both week 1 (adjusted beta -496.1, 95 % confidence interval [CI] -891.1, -101.1, p = 0.01) and beyond (adjusted beta -396.8; 95 % CI -727.2, -66.4. p = 0.02). Among the 15 participants who also had complete postpartum multiomics data available, there were predictive signatures of vaginal versus cesarean births in transcriptomics (cell-free [cf]RNA), metabolomics, microbiomics, and proteomics that did not persist after false discovery correction.

CONCLUSION

Maternal LTLs in postpartum week 1 were nearly 500 bp shorter following cesarean. This difference persisted several weeks postpartum, even though other markers of inflammation had normalized. Mode of delivery should be considered in any analyses of postpartum LTLs and further investigation into this phenomenon is warranted.

Distinct B cell profiles characterise healthy weight and obesity pre- and post-bariatric surgery

BACKGROUND/OBJECTIVES

Obesity-associated metabolic dysfunction and inflammation can be ameliorated by bariatric surgery. While obesity is also linked to impaired B cell activation, differentiation, and persistence in response to infection and vaccination little is known about post-operative immune B cell compartment and to what extent dysregulation in B cell pathways can be reversed. To bridge this gap in knowledge, we carried out in-depth evaluation of B cell composition in individuals with obesity prior to and following bariatric surgery compared to lean controls.

SUBJECTS/METHODS

We recruited individuals with obesity (BMI at least 35 kg/m2) before bariatric surgery (n = 21) and followed them up 6 months post-operatively (n = 17). As controls we recruited age- and sex-matched lean (BMI < 25) individuals (n = 18). We carried out comprehensive immunophenotyping of peripheral blood B cells as well as interrogated their association with inflammatory and metabolic parameters.

RESULTS

In obesity the balance of antigen-inexperienced and memory B cells in the peripheral blood is altered, with an expansion of naïve and a reduction in total memory B cells. 6 months following bariatric surgery this balance is restored. However, post-operative patients are uniquely characterised by an increase in B cell subsets associated with chronic inflammation - CD11c+CXCR5-IgD-CD27- double negative 2 (DN2) B cells and CD27+CD38++ plasmablasts. Correlations between B cells subsets, inflammatory and metabolic parameters were distinct in lean people and individuals with obesity pre- and post-bariatric surgery.

CONCLUSIONS

Bariatric surgery patients display a unique B cell profile 6 months post-operatively; this bears minimal resemblance to that of pre-operative patients and only partially overlaps with that of lean controls. Post-operative differences in the B cell compartment compared to lean controls are detected despite global amelioration of inflammation and restoration of metabolic health. Collectively, this indicates that bariatric surgery creates a specific immunometabolic state with potential implications for health outcomes.

Influence of bariatric surgery on the peripheral blood immune system of female patients with morbid obesity revealed by high-dimensional mass cytometry

Introduction

Obesity is associated with low-grade chronic inflammation, altered levels of adipocytokines, and impaired regulation of gastrointestinal hormones. Secreted, these factors exert immunostimulatory functions directly influencing peripheral immune cells.

Methods

In the realm of this study, we aimed to investigate the composition and activation status of peripheral blood immune cells in female patients with morbid obesity compared to lean controls using high-dimensional mass cytometry. Besides, we also assessed the influence of bariatric surgery with respect to its ability to reverse obesity-associated alterations within the first-year post-surgery.

Results

Patients with morbid obesity showed typical signs of chronic inflammation characterized by increased levels of CRP and fibrinogen. Apart from that, metabolic alterations were characterized by increased levels of leptin and resistin as well as decreased levels of adiponectin and ghrelin compared to the healthy control population. All these however, except for ghrelin levels, rapidly normalized after surgery with regard to control levels. Furthermore, we found an increased population of monocytic CD14⁺, HLA-DR^-, CD11b⁺, CXCR3⁺ cells in patients with morbid obesity and an overall reduction of the HLA-DR monocytic expression compared to the control population. Although CD14⁺, HLA-DR^-, CD11b⁺, CXCR3⁺ decreased after surgery, HLA-DR expression did not recover within 9 - 11 months post-surgery. Moreover, compared to the control population, patients with morbid obesity showed a perturbed CD4+ T cell compartment, characterized by a strongly elevated CD127⁺ memory T cell subset and decreased naïve T cells, which was not recovered within 9 - 11 months post-surgery. Although NK cells showed an activated phenotype, they were numerically lower in patients with morbid obesity when compared to healthy controls. The NK cell population further decreased after surgery and did not recover quantitatively within the study period.

Conclusions

Our results clearly demonstrate that the rapid adaptions in inflammatory parameters and adipocytokine levels that occur within the first year post-surgery do not translate to the peripheral immune cells. Apart from that, we described highly affected, distinct immune cell subsets, defined as CD127⁺ memory T cells and monocytic CD14⁺, HLA-DR, CD11b⁺, CXCR3⁺ cells, that might play a significant role in understanding and further decoding the etiopathogenesis of morbid obesity.

Association of telomere length with risk of complications in adult spinal deformity surgery: a pilot study of 43 patients

OBJECTIVE

Risk stratification is a critical element of surgical planning. Early tools were fairly crude, while newer instruments incorporate disease-specific elements and markers of frailty. It is unknown if discrepancies between chronological and cellular age can guide surgical planning or treatment. Telomeres are DNA-protein complexes that serve an important role in protecting genomic DNA. Their shortening is a consequence of aging and environmental exposures, with well-established associations with diseases of aging and mortality. There are compelling data to suggest that telomere length can provide insight toward overall health. The authors sought to determine potential associations between telomere length and postoperative complications.

METHODS

Adults undergoing elective surgery for spinal deformity were prospectively enrolled. Telomere length was measured from preoperative whole blood using quantitative polymerase chain reaction and expressed as the ratio of telomere (T) to single-copy gene (S) abundance (T/S ratio), with higher T/S ratios indicating longer telomere length. Demographic and patient data included age, BMI, and results for the following rating scales: the Adult Spinal Deformity Frailty Index (ASD-FI), Oswestry Disability Index (ODI), Scoliosis Research Society-22r (SRS-22r), American Society of Anesthesiology (ASA) classification, and Charlson Comorbidity Index (CCI). Operative and postoperative complication data (medical or surgical within 90 days) were also collected.

RESULTS

Forty-three patients were enrolled, including 31 women (53%), with a mean age of 66 years and a mean BMI of 28.5. The mean number of levels fused was 11, with 21 (48.8%) combined anterior-posterior approaches. Twenty-two patients (51.2%) had a medical or surgical complication. Patients with a postoperative complication had a significantly lower T/S ratio (0.712 vs 0.813, p = 0.008), indicating shorter telomere length, despite a mild difference in age compared with patients without a postoperative complication (68 vs 63 years, p = 0.069). Patients with complications also had higher CCI scores than patients without complications (2.3 vs 3.8, p = 0.004). There were no significant differences in sex, BMI, ASD-FI score, ASA class, preoperative ODI and SRS-22r scores, number of levels fused, or use of three-column osteotomies. In a multivariate model including age, frailty, ASA class, use of an anterior-posterior approach, CCI score, and telomere length, the authors found that short telomere length was significantly associated with postoperative complications. Patients whose telomere length fell in the shortest quartile had the highest risk (OR 18.184, p = 0.030).

CONCLUSIONS

Short telomere length was associated with an increased risk of postoperative complications despite only a mild difference in chronological age. Increasing comorbidity scores also trended toward significance. Larger prospective studies are needed; however, these data provide a compelling impetus to investigate the role of biological aging as a component of surgical risk stratification.

Telomere length dynamics measured by flow-FISH in patients with obesity undergoing bariatric surgery

Obesity has negative effects on comorbidities, health-related quality of life and survival. Telomere length (TL) changes after bariatric surgery have been reported, but the studies are contradictory, and analyses using state-of-the art techniques for TL measurement, such as flow-FISH, are sparse. We measured TL dynamics via flow-FISH in patients undergoing bariatric surgery and compared their TL with 105 healthy individuals. Patients with obesity who underwent bariatric surgery were included. Lymphocyte and granulocyte absolute and age-adjusted (aa) TL were analyzed by flow-FISH before (preoperative cohort, n = 45) and after surgery (follow-up cohort, n = 35) at month 5.5 ± 3.9 (mean ± standard deviation [SD]). The initial lymphocyte aaTL was significantly shorter (-0.37 kb ± 0.18 kb, P = 0.045) in patients with obesity, while the granulocyte aaTL was not different from that in the healthy comparison population (0.28 kb ± 0.17 kb, P = 0.11). The telomere dynamics after surgery showed an increase in mean TL in both lymphocytes and granulocytes of patients with a pronounced BMI loss of ≥ 10 kg/m². We did not find any association between TL increase after surgery and age, sex or the type of procedure selected for bariatric surgery. We confirmed that patients suffering from obesity have significantly shorter lymphocyte TL using flow-FISH. Along with and dependent on the degree of weight reduction after bariatric surgery, TL significantly increased in both lymphocytes and granulocytes after a mean of 5.5 months. Our results show that bariatric surgery affects not only body weight but also biomarkers of aging, such as TL.

The role of bariatric and metabolic surgery in the development, diagnosis, and treatment of endometrial cancer

The obesity pandemic continues to contribute to a worsening burden of disease worldwide. The link between obesity and diseases such as diabetes, cardiovascular disease, and cancer has been well established, yet most patients living with obesity remain untreated or undertreated. Metabolic and bariatric surgery is the most effective and durable treatment for obesity, is safe, and may have a protective benefit with respect to cancer incidence. In this review, an overview of the link between obesity, metabolic surgery, and cancer is discussed with emphasis on indications for endometrial cancer, the malignancy most strongly associated with obesity. Considerable evidence from retrospective and prospective cohort studies supports a decreased risk of endometrial cancer in patients with obesity who undergo bariatric surgery compared with nonsurgical controls. Survivors of endometrial cancer are at increased risk of poor health outcomes associated with obesity, and women with endometrial cancer are more likely to die of cardiovascular disease and other obesity-related illnesses than of the malignancy itself. Recent advances in anticancer drug therapies have targeted pathways that may also be therapeutically altered with metabolic surgery. Metabolic surgery has significant potential to enter the treatment paradigm for endometrial cancer, and gynecologic oncologist visits present an opportunity to identify patients who may benefit the most.

T and B Cell Composition and Cytokine Producing Capacity Before and After Bariatric Surgery

Morbid obesity is associated with a chronic state of low-grade inflammation, which may lead to accelerated differentiation of T and B cells. These differentiated immune cells are strongly cytotoxic and have an increased pro-inflammatory cytokine producing capacity. Furthermore, the anti-inflammatory function of the T and B cells decreases. The aim of this study was to evaluate the effect of morbid obesity on the subset profile and cytokine producing capacity of T and B cells. Subsequently, we assessed whether bariatric surgery affected the subset profile and cytokine producing capacity of these cells. We determined the proportion of T and B cell subsets and their cytokine producing capacity in peripheral blood collected from 23 morbidly obese patients before and three months after bariatric surgery using flow-cytometry. We compared this with the results of 25 lean controls. Both CD4+ and CD8+ T cells showed a more differentiated subset profile in morbidly obese patients as compared to lean controls, which was not recovered three months after bariatric surgery. The B cell composition of morbidly obese patients after bariatric surgery adjusted towards the profile of lean controls. However, the IL-2 and IFN-γ producing capacity of CD8+ T cells and the IL-2, IFN-γ, TNF-α and IL-10 producing capacity of B cells was not restored three months after bariatric surgery. In conclusion, the data suggest that the immune system has the capacity to recover from the detrimental effects of morbid obesity within three months after bariatric surgery in terms of cell composition; however, this was not seen in terms of cytokine producing capacity. The full restoration of the immune system after bariatric surgery may thus take longer.

The tumor suppression theory of aging

Despite continued increases in human life expectancy, the factors determining the rate of human biological aging remain unknown. Without understanding the molecular mechanisms underlying aging, efforts to prevent aging are unlikely to succeed. The tumor suppression theory of aging introduced here proposes somatic mutation as the proximal cause of aging, but postulates that oncogenic transformation and clonal expansion, not functional impairment, are the relevant consequences of somatic mutation. Obesity and caloric restriction accelerate and decelerate aging due to their effect on cell proliferation, during which most mutations arise. Most phenotypes of aging are merely tumor-suppressive mechanisms that evolved to limit malignant growth, the dominant age-related cause of death in early and middle life. Cancer limits life span for most long-lived mammals, a phenomenon known as Peto's paradox. Its conservation across species demonstrates that mutation is a fundamental but hard limit on mammalian longevity. Cell senescence and apoptosis and differentiation induced by oncogenes, telomere shortening or DNA damage evolved as a second line of defense to limit the tumorigenic potential of clonally expanding cells, but accumulating senescent cells, senescence-associated secretory phenotypes and stem cell exhaustion eventually cause tissue dysfunction and the majority, if not most, phenotypes of aging.

Childhood Adiposity Associated With Expanded Effector Memory CD8+ and Vδ2+Vγ9+ T Cells

CONTEXT

Adult obesity is associated with chronic low-grade inflammation and may give rise to future chronic disease. However, it is unclear whether adiposity-related inflammation is already apparent in childhood.

OBJECTIVE

To study associations between child adiposity measures with circulating monocytes and naive and memory subsets in CD4, CD8, and γδ T cell lineages.

METHODS

Ten-year-old children (n = 890) from the Generation R Cohort underwent dual-energy x-ray absorptiometry and magnetic resonance imaging for body composition (body mass index [BMI], fat mass index [FMI], android-to-gynoid fat mass ratio, visceral fat index, liver fat fraction). Blood samples were taken for detailed immunophenotyping of leukocytes by 11-color flow cytometry.

RESULTS

Several statistically significant associations were observed. A 1-SD increase in total FMI was associated with +8.4% (95% CI 2.0, 15.2) Vδ2+Vγ9+ and +7.4% (95% CI 2.4, 12.5) CD8+TEMRO cell numbers. A 1-SD increase in visceral fat index was associated with +10.7% (95% CI 3.3, 18.7) Vδ2+Vγ9+ and +8.3% (95% CI 2.6, 14.4) CD8+TEMRO cell numbers. Higher android-to-gynoid fat mass ratio was only associated with higher Vδ2+Vγ9+ T cells. Liver fat was associated with higher CD8+TEMRO cells but not with Vδ2+Vγ9+ T cells. Only liver fat was associated with lower Th17 cell numbers: a 1-SD increase was associated with -8.9% (95% CI -13.7, -3.7) Th17 cells. No associations for total CD8+, CD4+ T cells, or monocytes were observed. BMI was not associated with immune cells.

CONCLUSION

Higher Vδ2+Vγ9+ and CD8+TEMRO cell numbers in children with higher visceral fat index could reflect presence of adiposity-related inflammation in children with adiposity of a general population.

Telomere length in patients with obesity submitted to bariatric surgery: A systematic review

BACKGROUND

Patients with obesity show evidence of increased levels of inflammation, oxidative stress and premature ageing. Telomere length (TL) is a key marker of cellular ageing, and patients with obesity often present shorter TL. Bariatric surgery (BS) is currently the most effective treatment for severe obesity. The aim of this systematic review was to explore whether the beneficial health effects observed after surgery in obese patients correspond to a restoration in TL or slower rates of shortening. As a secondary aim, we evaluated, at baseline and post-surgery, the relationship between TL and different factors that could play a role in TL changes along time.

METHODS

Searches for relevant articles were performed in MEDLINE, Web of Knowledge and SCOPUS. Prospective longitudinal studies that evaluated leukocyte TL in adult patients who had undergone BS were included. Data were extracted and evaluated by two independent researchers. The protocol was registered in PROSPERO with the number CRD42020197711.

RESULTS

Seven studies based on independent samples that fulfilled our inclusion criteria were included. Obese patients showed shorter telomeres compared to healthy individuals. Long-term studies (>2 years) seem to suggest an improvement in TL after surgery presumably due to the improvement of the inflammatory and oxidative levels of the patients induced by weight loss.

CONCLUSION

Studies seem to point towards a beneficial long-term effect of BS on TL recovery. However, the scarce number of studies and the heterogeneity in the variables analysed in the different cohorts make it difficult to draw a firm conclusion. More studies are needed to evaluate long-term changes to TL following BS.

Effects of Morbid Obesity and Metabolic Syndrome on the Composition of Circulating Immune Subsets

Morbid obesity is characterized by chronic, low-grade inflammation, which is associated with ‘inflamm-aging’. The presence of metabolic syndrome (MetS) might accelerate this phenomenon of metaflammation. In this study, we assessed the effects of morbid obesity and MetS on the composition of a broad spectrum of immune cells present within the circulation. A total of 117 morbidly obese patients (MOP) without MetS (MetS-), 127 MOP with MetS (MetS+) and 55 lean controls (LC) were included in this study. Absolute numbers of T cell, B cell, NK cell and monocyte subsets were assessed within peripheral blood using flow cytometry. Both absolute cell numbers and proportion of cells were evaluated correcting for covariates age, body mass index and cytomegalovirus serostatus. Although the absolute number of circulating CD4+ T cells was increased in the MetS+ group, the CD4+ T cell composition was not influenced by MetS. The CD8+ T cell and B cell compartment contained more differentiated cells in the MOP, but was not affected by MetS. Even though the absolute numbers of NK cells and monocytes were increased in the MOP as compared to LC, there was no difference in proportions of NK and monocyte subsets between the three study groups. In conclusion, although absolute numbers of CD4+ and CD8+ T cells, B cells, NK cells and monocytes are increased in MOP, obesity-induced effects of the composition of the immune system are confined to a more differentiated phenotype of CD8+ T cells and B cells. These results were not affected by MetS.

Stapleless vs Stapled Gastric Bypass vs Hypocaloric Diet: a Three-Arm Randomized Controlled Trial of Body Mass Evolution with Secondary Outcomes for Telomere Length and Metabolic Syndrome Changes

BACKGROUND

Obesity and metabolic syndrome (MetS) reduce life expectancy and are challenging to resolve. This randomized controlled trial (RCT) of patients with obesity and MetS undergoing surgical vs nonsurgical treatment compared changes in BMI, and secondarily, telomere length (as a biomarker of life expectancy) and changes in MetS components (insulin resistance, dyslipidemia, hypertension).

METHODS

Study design was a single-center, prospective, three-arm RCT. Group 1 patients underwent novel unstapled laparoscopic one anastomosis gastric bypass with an obstructive stapleless pouch and anastomosis (LOAGB-OSPAN); Group 2, stapled laparoscopic mini-gastric bypass-one anastomosis gastric bypass (LMGB-OAGB); and Group 3, nonsurgical weight loss therapy via a hypocaloric diet with energy restriction (HDER). The primary outcome measure was change in BMI; secondary outcome measures included change in leukocyte telomere length and other MetS components.

RESULTS

Of 96 participants screened, 60 were randomly allocated to 3 groups: LOAGB-OSPAN group (n = 20), LMGB-OAGB group (n = 20), and HDER group (n = 20). At post-treatment month 12, respective BMI changes: BMI -12.13 (-8.34, -15.93); -16.04 (-11.7, 20.37); -2,76 (-3.84, -9.36) (p < 0.01). The two surgical groups experienced significant change in telomere length: LOAGB-OSPAN 2.02 (1.61, 2.41), p = 0.001; LMGB-OAGB 2.07 (1.72, 2.43), p = 0.001; and HDER 0.28 (0.22, 0.78), p = 0.26. The surgical groups were also more effective in treating MetS components. There were no deaths. Adverse events: LOAGB-OSPAN (n = 2) (Clavien-Dindo grade II); LMGB-OAGB (n = 8) (grade I (n = 6) and grade II (n = 2).

CONCLUSIONS

Compared with hypocaloric diet therapy, both bariatric procedures resulted in greater BMI loss, and secondarily, a significant increase in telomere length, and greater MetS resolution.

TRIAL REGISTRATION

ClinicalTrials.gov , NCT03667469, registered on 11 September 2018.

The Immunophenotyping Changes of Peripheral CD4+ T Lymphocytes and Inflammatory Markers of Class III Obesity Subjects After Laparoscopic Gastric Sleeve Surgery - A Follow-Up Study

Purpose

Obesity is a chronic disorder characterized by a low-grade inflammatory state and immune cell irregularities. The study aimed to follow up on the changes in the peripheral CD4+ T lymphocytes and the pro-inflammatory cytokines; IL-6, TNF-alpha, MCP-1, and IL-10 at baseline and 12 weeks post-surgical intervention by the laparoscopic gastric sleeve (LGS) in morbidly obese patients (class III obesity subjects).

Materials and Methods

A prospective longitudinal research included 24 class III obesity subjects with a BMI > 40 kg/m². The subjects were enrolled from the Metabolic/Surgical Department at Hamad Medical Corporation (HMC)-Qatar. Fasting blood samples were collected at admission to LGS for weight loss and after 12 weeks of LGS. The immunophenotype of CD4+ T-cell populations; naïve (CD45RA⁺and CD27⁺), central memory T cells (CD45RO⁺ and CD27⁺), and effector memory (CD45RO⁺and CD27^-) and T-regulatory cell (CD4+CD25+ FoxP3+) were identified using flow cytometry. Plasma pro-inflammatory cytokines and adipokines were evaluated. A control group of lean subjects was used to compare changes of T-regulatory and inflammatory biomarkers with postoperative changes in obese patients.

Results

The means (SD) of age and BMI of class III obesity subjects was 32.32 (8.36) years and 49.02 (6.28) kg/m^2, respectively. LGS caused a significant reduction in BMI by 32%, p<0.0001. LGS intervention significantly decreased CD4+ T-lymphocytes and effector memory (TEM) cells but increased T-regulatory (Treg), naïve, and central memory (TCM) cells, with all p values < 0.05. The increase of Treg cells postoperative is significantly lower compared to lean subjects, p < 0.05. A significant reduction of plasma IL-6, TNF-α, and MCP-1, but IL-10 significantly increased after LGS, with all p<0.05. Adiponectin/leptin ratio improved after LGS by 2.9 folds, p<0.0001.

Conclusion

Weight loss by LGS accomplished a substantial rise of Treg and decreased EM T-lymphocytes with a shift from pro-inflammatory to the anti-inflammatory pattern.

Uremia-Associated Immunological Aging and Severity of COVID-19 Infection

One year after the start of the COVID-19 pandemic it has become clear that some groups of individuals are at particular high risk of a complicated course of infection resulting in high morbidity and mortality. Two specific risk factors are most prominent, old age and the presence of co-morbidity. Recent studies have shown that patients with compromised renal function, especially those treated with renal replacement therapy or having received a kidney transplant are at a much higher risk for severe COVID infection and increased mortality. This may be in part due to the increased prevalence of co-morbid conditions in these patients but specific alterations in their immune system, reflecting premature immunological aging, may be equally important. In this review the different aspects, in particular thymus function and memory T cell expansion, of uremia-associated immunological aging are reviewed with respect to COVID 19 infection. In essence, the decreased generation of naïve T cells may be instrumental in suboptimal anti-viral immune responses while the relatively uncontrolled expansion of effector T cells may facilitate the feared phase of the COVID-19 infection with excessive and live-threatening inflammation of the lung parenchyma.

Acyl-CoA-binding protein (ACBP): a phylogenetically conserved appetite stimulator

Recently, we reported that, in mice, hunger causes the autophagy-dependent release of a protein called "acyl-CoA-binding protein" or "diazepam binding inhibitor" (ACBP/DBI) from cells, resulting in an increase in plasma ACBP concentrations. Administration of extra ACBP is orexigenic and obesogenic, while its neutralization is anorexigenic in mice, suggesting that ACBP is a major stimulator of appetite and lipo-anabolism. Accordingly, obese persons have higher circulating ACBP levels than lean individuals, and anorexia nervosa is associated with subnormal ACBP plasma concentrations. Here, we investigated whether ACBP might play a phylogenetically conserved role in appetite stimulation. We found that extracellular ACBP favors sporulation in Saccharomyces cerevisiae, knowing that sporulation is a strategy for yeast to seek new food sources. Moreover, in the nematode Caenorhabditis elegans, ACBP increased the ingestion of bacteria as well as the frequency pharyngeal pumping. These observations indicate that ACBP has a phylogenetically ancient role as a 'hunger factor' that favors food intake.

The Impact of Obesity and Lifestyle on the Immune System and Susceptibility to Infections Such as COVID-19

Background: COVID-19 is a global challenge to healthcare. Obesity is common in patients with COVID-19 and seems to aggravate disease prognosis. In this review we explore the link between obesity, chronic disease, lifestyle factors and the immune system, and propose societal interventions to enhance global immunity. Search Strategy and Selection Criteria: We performed three literature searches using the keywords (1) coronavirus AND comorbidities, (2) comorbidities AND immune system, and (3) lifestyle factors AND immune system. Results were screened for relevance by the main author and a total of 215 articles were thoroughly analyzed. Results: The relationship between obesity and unfavorable COVID-19 prognosis is discussed in light of the impact of chronic disease and lifestyle on the immune system. Several modifiable lifestyle factors render us susceptible to viral infections. In this context, we make a case for fostering a healthy lifestyle on a global scale. Conclusions: Obesity, additional chronic disease and an unhealthy lifestyle interactively impair immune function and increase the risk of severe infectious disease. In adverse metabolic and endocrine conditions, the immune system is geared toward inflammation. Collective effort is needed to ameliorate modifiable risk factors for obesity and chronic disease on a global scale and increase resistance to viruses like SARS-CoV-2.