A possible secondary immune response in adipose tissue during weight cycling: The ups and downs of yo-yo dieting

Body weight variability and the risk of liver-related outcomes in type 2 diabetes and steatotic liver disease: a cohort study

OBJECTIVE

The objective of this study was to evaluate the effects of body weight variability (BWV) on the occurrence of adverse liver outcomes in individuals with type 2 diabetes (T2D) and metabolic dysfunction-associated steatotic liver disease (MASLD).

METHODS

A total of 549 patients with T2D and MASLD had BWV parameters assessed during the first 2 years of follow-up. The associations between increasing BWV and liver outcomes (clinical cirrhosis or a liver stiffness measurement on transient elastography > 15 kPa, performed after a median of 7 years of cohort entry) were examined by multivariable logistic regressions. Interaction/subgroup analyses were performed according to participants' physical activity during the initial 2-year period.

RESULTS

Individuals were followed up for an additional median 9.7 years, over which 34 liver outcomes occurred (14 with clinical cirrhosis and 20 with liver stiffness measurement > 15 kPa). A 1-SD increase in weight SD and average real variability was associated with 52% higher (95% CI: 4%-128%) odds of having an adverse liver outcome. Otherwise, in interaction/subgroup analyses, an increased BWV was associated with a higher likelihood of outcomes only in sedentary individuals.

CONCLUSIONS

Increased BWV was associated with adverse liver outcomes in individuals with T2D and MASLD; however, in those who were physically active, it was not hazardous.

Single cell RNA-sequencing suggests a novel lipid associated mast cell population following weight cycling

Our recent study showed weight cycled mice have increased adipose mast cells compared to obese mice by single cell RNA-sequencing. Here, we aimed to confirm and elucidate these changes. Further analysis of our dataset showed that our initial mast cell cluster could subcluster into two unique populations: one with very high expression of classical mast cell markers and another with elevated lipid handling and antigen presentation genes. This new mast cell cluster accounted for most of the mast cells in the weight cycled group although it was not possible to detect the different populations by new studies with flow cytometry or Toluidine blue staining in mice, possibly due to a downregulation in classical mast cell genes. Interestingly, a pilot study in humans did suggest the existence of two mast cell populations in subcutaneous adipose tissue from obese women that appear similar to the murine populations detected by sequencing; one of which was significantly correlated with weight variance. Together, these data suggest that weight cycling may induce a unique population of mast cells similar to lipid associated macrophages. Future studies will focus on isolation of these cells to better determine their lineage, differentiation, and functional roles.

Weight cycling based on altered immune microenvironment as a result of metaflammation

As a result of the obesity epidemic, more people are concerned about losing weight; however, weight regain is common, leading to repeated weight loss and weight cycling. The health benefits of early weight loss are nullified by weight regain after weight cycling, which has much more severe metabolic consequences. Weight cycling alters body composition, resulting in faster fat recovery and slower muscle reconstruction. This evident fat accumulation, muscle loss, and ectopic fat deposition destroy the intestinal barrier, increase the permeability of the small intestinal epithelium, and cause the lipotoxicity of lipid metabolites and toxins to leak into extraintestinal tissues and circulation. It causes oxidative stress and hypoxia in local tissues and immune cell infiltration in various tissues, all contributing to the adaptation to this metabolic change. Immune cells transmit inflammatory responses in adipose and skeletal muscle tissue by secreting cytokines and adipokines, which mediate immune cell pathways and cause metaflammation and inefficient metabolic degradation. In this review, we focus on the regulatory function of the immunological microenvironment in the final metabolic outcome, with a particular emphasis on the cellular and molecular processes of local and systemic metaflammation induced by weight cycling-induced changes in body composition. Metaflammation in adipose and muscle tissues that is difficult to relieve may cause weight cycling. As this chronic low-grade inflammation spreads throughout the body, metabolic complications associated with weight cycling are triggered. Inhibiting the onset and progression of metabolic inflammation and enhancing the immune microenvironment of adipose and muscle tissues may be the first step in addressing weight cycling.

Obesogenic Memory Maintains Adipose Tissue Inflammation and Insulin Resistance

Background:

Obesity is characterized by visceral adipose tissue (AT) inflammation. Immunosuppressive regulatory T cells (Tregs), phagocytic M2-like macrophages, and innate lymphoid cells type 2 (ILC2) control lean AT inflammation to maintain systemic insulin sensitivity, while the loss of these cells in obesity leads to AT inflammation and insulin resistance (IR).

Objective:

The objective of this study was to determine if weight loss following obesity would correct AT inflammation and systemic metabolism.

Results:

After six months of high fat diet (HFD) in male C57/Bl6 mice, flow analyses of epidydimal AT stromal vascular fraction (SVF) revealed depleted Tregs by 50%, doubling of CD8⁺ T cells, tripling of pro-inflammatory M1-like macrophages, and an 80% drop in ILC2 cells associated with changes in pro-inflammatory adipocyte and macrophage gene expression. Despite normalization of body weight, fat, and adipocyte size, mice ingesting 3 months of high-fat diet (HFD) followed by 3 months of chow-diet remained more insulin resistant and glucose intolerant than chow-fed animals. Adipocytes, AT Tregs, CD8⁺ T cells, ILC2 cells, and M1-like macrophages all failed to normalize with weight loss.

Conclusions:

Persistent AT inflammation contributes to the maintenance of IR despite body weight and fat normalization in previously obese mice. These findings highlight the importance of obesity prevention to avoid the consequences of “obesogenic memory.”

Adaptive Immunity and Metabolic Health: Harmony Becomes Dissonant in Obesity and Aging

Adipose tissue (AT) is the primary energy reservoir organ, and thereby plays a critical role in energy homeostasis and regulation of metabolism. AT expands in response to chronic overnutrition or aging and becomes a major source of inflammation that has marked influence on systemic metabolism. The chronic, sterile inflammation that occurs in the AT during the development of obesity or in aging contributes to onset of devastating diseases such as insulin resistance, diabetes, and cardiovascular pathologies. Numerous studies have shown that inflammation in the visceral AT of humans and animals is a critical trigger for the development of metabolic syndrome. This work underscores the well-supported conclusion that the inflammatory immune response and metabolic pathways in the AT are tightly interwoven by multiple layers of relatively conserved mechanisms. During the development of diet-induced obesity or age-associated adiposity, cells of the innate and the adaptive immune systems infiltrate and proliferate in the AT. Macrophages, which dominate AT-associated immune cells in mouse models of obesity, but are less dominant in obese people, have been studied extensively. However, cells of the adaptive immune system, including T cells and B cells, contribute significantly to AT inflammation, perhaps more in humans than in mice. Lymphocytes regulate recruitment of innate immune cells into AT, and produce cytokines that influence the helpful-to-harmful inflammatory balance that, in turn, regulates organismal metabolism. This review describes inflammation, or more precisely, metabolic inflammation (metaflammation) with an eye toward the AT and the roles lymphocytes play in regulation of systemic metabolism during obesity and aging. © 2017 American Physiological Society. Compr Physiol 7:1307-1337, 2017.

Persimmon vinegar ripening with the mountain-cultivated ginseng ingestion reduces blood lipids and lowers inflammatory cytokines in obese adolescents

[Purpose]

This study investigated the effect of the vinegar, which is made of 4-year-old mountain-cultivated ginseng ripened into 4-year-matured persimmon vinegar, on the blood lipids level and inflammatory cytokines concentration in obese female adolescents.

[Methods]

Subjects ingested the vinegar, so-called 'mountain-cultivated ginseng persimmon vinegar (MPV)', without meals every day for 6 weeks with activities control. Subjects were grouped into control (CON), persimmon vinegar (PV), and MPV with 10 people in each group. Blood lipids, triglyceride (TG), total-cholesterol (TC), and high density lipoprotein-cholesterol (HDL-C) were analyzed. Also, glutamic oxaloacetic transaminase (GOT) and glutamate pyruvate transaminase (GPT) were analyzed for the hepatotoxicity. Blood cytokines, interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) were analyzed.

[Results]

Subjects showed a high reduction in body weight and body fat. Their blood lipid level was effectively improved, and the secretion of inflammatory cytokine was suppressed as well, except for TNF-α. However, the change ratio of the cytokines was high in PV and MPV. Such results were similar to those from research subjects who took persimmon vinegar only (PV), but the effect of the vinegar (MPV) was more remarkable. Besides, this mixture was found to have no effect on the hepatotoxicity.

[Conclusion]

The significance of this study is that all the experiments were conducted without controlling research subjects' daily lives, and it is suggested that the vinegar may be recommended as a kind of health supplement food to suppress obesity. Especially, since these two products are traditional foods of Korean people, which have been taken for ages, it is expected that the fusing of two foods may be better applied to ordinary people who are concerned about obesity.