Interleukin-10 (IL-10) is a critical cytokine used by immune cells to suppress inflammation. Paradoxically, immune cell–derived IL-10 can drive insulin resistance in obesity by suppressing adipocyte energy expenditure and thermogenesis. However, the source of IL-10 necessary for the suppression of adipocyte thermogenesis is unknown. We show here that CD4 + Foxp3 + regulatory T cells (Tregs) are a substantial source of IL-10 and that Treg-derived IL-10 can suppress adipocyte beiging. Unexpectedly, Treg-specific loss of IL-10 resulted in increased insulin sensitivity and reduced obesity in high-fat diet–fed male mice. Mechanistically, we determined that Treg-specific loss of the transcription factor Blimp-1, a driver of IL-10 expression by Tregs, phenocopied the Treg-specific IL-10–deficient mice. Loss of Blimp-1 expression in Tregs resulted in reduced ST2 + KLRG1 + , IL-10-secreting Tregs, particularly in the white adipose tissue. Blimp-1–deficient mice were protected from glucose intolerance, insulin resistance, and diet-induced obesity, through increased white adipose tissue browning. Taken together, our data show that Blimp-1–regulated IL-10 secretion by Tregs represses white adipose tissue beiging to maintain adipose tissue homeostasis.

Objective: To explore the use of ChatGPT by educators and students in a medical school setting. Method: This study used the public version of ChatGPT launched by OpenAI on November 30, 2022 (https://openai.com/blog/chatgpt/). We employed prompts to ask ChatGPT to 1) generate a content outline for a session on the topics of cholesterol, lipoproteins, and hyperlipidemia for medical students; 2) produce a list of learning objectives for the session; and 3) write assessment questions with and without clinical vignettes related to the identified learning objectives. We assessed the responses by ChatGPT for accuracy and reliability to determine the potential of the chatbot as an aid to educators and as a know-it-all medical information provider for students. Results: ChatGPT can function as an aid to educators, but it is not yet suitable as a reliable information resource for educators and medical students. Conclusion: ChatGPT can be a useful tool to assist medical educators draft course and session content outlines and create assessment questions. At the same time, caution must be taken as ChatGPT is prone to providing incorrect information; expert oversight and caution are necessary to ensure the information generated is accurate and beneficial to students. Therefore, it is premature for medical students to use the current version of ChatGPT as a know-it-all information provider. In the future, medical educators should work with programming experts to explore and grow the full potential of AI in medical education.

Chronic obesity occurs when there is imbalance between caloric intake and energy expenditure. It is now clear that immune cells, through their communication with adipocytes, can drive or suppress adipocyte energy expenditure, thus regulating weight gain and obesity. Adipose tissue resident regulatory T cells (aTregs) are a dominant, unique CD4+ T cell population in the adipose tissue depots of mice and humans. Here we show that the transcription factor Activating Transcription Factor 3 (Atf3), defines a population of aTregs that secrete opioid-like peptides called Methionine-Enkephalins (Met-Enk). We show that aTreg-derived Met-Enk increases adipocyte function and energy expenditure by upregulating Uncoupling Protein 1 (Ucp-1) and other genes associated with adipocyte thermogenesis. Loss of Atf3 expression in aTregs, resulted in loss of Met-Enk expressing aTregs and conversely, resulted in increased Interelukin-10 (IL-10)-secreting aTregs. Physiologically, Atf3+ aTregs are required to maintain metabolic homeostasis and loss of Atf3+ aTregs increased insulin resistance in mice. Taken together, our data reveal that distinct aTreg populations with unique gene expression and cytokine secretion profiles, work together to modulate adipocyte function and energy expenditure.

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Visceral adipose tissue regulatory T cells (VAT Tregs) protect against systemic inflammation and metabolic disease by limiting expansion of pro-inflammatory Th1 cells and M1 macrophages, and by preserving insulin sensitivity and glucose tolerance. Although their basic markers and roles have been studied, less is known about the transcriptional machinery regulating their differentiation and function. B lymphocyte-induced maturation protein-1 (Blimp-1) is a transcriptional regulator known to be involved in the development, polarization, and maintenance of various immune cells including CD4+ T cells. Using Blimp-1 reporter mice, we discovered that Blimp-1 is constitutively expressed in a subset of VAT Tregs compared to lymphoid Tregs, and that Blimp-1+ VAT Tregs are phenotypically distinct from their Blimp-1− counterparts. Blimp-1 is not required for VAT Treg development, however Treg-specific deletion of Blimp-1 led to unique changes in VAT Treg markers in lean versus obese adipose tissue. In addition, Blimp-1 knockout mice fed high fat diet had fewer adipose-resident NK cells and increased CD8 T cells. Surprisingly, loss of Blimp-1+ Tregs led to less adipose tissue IL-10, increased expression of thermogenic genes, reduced body fat, decreased weight, and improved insulin sensitivity. Based on these data, we hypothesize that Blimp-1+ Treg dependent IL-10 production suppresses adipocyte beiging, and that loss of these cells results in increased thermogenesis, greater weight loss and improved insulin sensitivity in obese mice.