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Understanding how differences in animal husbandry practices affect the reproducibility of research results is critical. We sought to understand how different beddings might influence dietary obesity studies. We compared the effects of paper and corncob bedding on weight gain, metabolism, and gut microbiome (GM) of mice fed a high-fat diet (HFD) or a normal diet (ND) and evaluated effects on fecal and cecal microbiomes collected from these cohorts after euthanasia. Male C57BL/6J mice at 5 wk age were allowed to acclimate to the facility and the assigned bedding for one week before being placed on HFD or remaining on the ND for 12 wk. Fecal pellets and cecal samples were collected and frozen for batched 16S sequencing. Mice had similar body weight, visceral gonadal white adipose tissue (GWAT), subcutaneous inguinal white adipose tissue (IWAT), liver and spleen weights and metabolic changes regardless of the bedding type. Baseline microbiota differences were detected one week after bedding assignment. After 12 wk, the GM showed significant differences depending on both bedding and diet. The effects of the bedding were not significantly different between endpoint fecal and cecal GM, despite the inherent differences in microbiota in fecal and cecal samples. A correlation was detected between diet and the relative abundance of Bacteroidetes and Verrucomicrobia: Akkermansia. In conclusion, this study demonstrates the importance of considering bedding type when performing dietary experiments.

Obesity-induced inflammation is a risk factor for metabolic impairment leading to diabetes and cardiovascular disease. We, and others, have shown that sex differences exist in adipose tissue (AT) and myeloid inflammatory responses to high-fat diet (HFD) and lipolysis. However, the causal cellular mechanisms behind this sexual dimorphism are not well defined. Our objective was to investigate sex differences in lipid storage and metabolism that drive sexually dimorphic inflammatory responses. C57Bl/6J mice were fed a normal diet or 60%kcal%fat (HFD) for 16 weeks. AT macrophages (ATMs) were sorted for RNA sequencing. Animals were gonadectomized (GX) prior to starting HFD and gonadal white AT (GWAT) was collected for lipidomics. To directly model androgen receptor (AR) activation, GX mice were given dihydrotestosterone (DHT) to study AR-specific effects. RNA sequencing identified upregulated genes (Lpl, Ctsb, and Cd36) linked to a metabolically-activated macrophage only in male HFD ATMs. Furthermore, pathways associated with mitochondrial depolarization and fatty acid (FA) metabolism differed significantly by sex. GWAT lipidomics identified shifts in lipid species both by sex and hormone status, and differences were also observed in acylcarnitines and saturation of ceramide species that are implicated in inflammation. In addition, males showed elevated levels of key precursor free FAs (palmitic, linoleic, and arachidonic acid) when compared to female and GX mice. DHT treatment did not completely mimic male pro-inflammatory responses but induced GWAT crown-like structures in both sexes. DHT failed to upregulate inflammatory markers (Il6 and Mcp1) but showed impaired expression of adipogenic genes (Pparg and Pgc1α) in GX mice. Altogether, our data suggest there are sex-specific alterations in GWAT lipid storage and metabolism that may drive sexually dimorphic ATM polarization, which is only partially reversed by AR activation. Disclosure R. Mohan: None. M. Varghese: None. S. Abrishami: None. K. Singer: None. Funding National Institutes of Health - NIDDK (R01DK115583)

BM adipocytes (BMAd) are a unique cell population derived from BM mesenchymal progenitors and marrow adipogenic lineage precursors. Although they have long been considered to be a space filler within bone cavities, recent studies have revealed important physiological roles in hematopoiesis and bone metabolism. To date, the approaches used to study BMAd function have been confounded by contributions by nonmarrow adipocytes or by BM stromal cells. To address this gap in the field, we have developed a BMAd-specific Cre mouse model to deplete BMAds by expression of diphtheria toxin A (DTA) or by deletion of peroxisome proliferator-activated receptor gamma (Pparg). We found that DTA-induced loss of BMAds results in decreased hematopoietic stem and progenitor cell numbers and increased bone mass in BMAd-enriched locations, including the distal tibiae and caudal vertebrae. Elevated bone mass appears to be secondary to enhanced endosteal bone formation, suggesting a local effect caused by depletion of BMAd. Augmented bone formation with BMAd depletion protects mice from bone loss induced by caloric restriction or ovariectomy, and it facilitates the bone-healing process after fracture. Finally, ablation of Pparg also reduces BMAd numbers and largely recapitulates high-bone mass phenotypes observed with DTA-induced BMAd depletion.

SummaryTo investigate roles for bone marrow adipocyte (BMAd) lipolysis in bone homeostasis, we created a BMAd-specific Cre mouse model in which we knocked out adipose triglyceride lipase (ATGL, Pnpla2). BMAd-Pnpla2-/- mice have impaired BMAd lipolysis, and increased size and number of BMAds at baseline. Although energy from BMAd lipid stores is largely dispensable when mice are fed ad libitum, BMAd lipolysis is necessary to maintain myelopoiesis and bone mass under caloric restriction. BMAd-specific Pnpla2 deficiency compounds the effects of caloric restriction on loss of trabecular bone, likely due to impaired osteoblast expression of collagen genes and reduced osteoid synthesis. RNA sequencing analysis of bone marrow adipose tissue reveals that caloric restriction induces dramatic elevations in extracellular matrix organization and skeletal development genes, and energy from BMAd is required for these adaptations. BMAd-derived energy supply is also required for bone regeneration upon injury, and maintenance of bone mass with cold exposure.

Obesity is associated with systemic inflammation and immune cell recruitment to metabolic tissues. Sex differences have been observed where male mice challenged with high fat diet (HFD) exhibit greater adipose tissue inflammation than females demonstrating a role for sex hormones in differential inflammatory responses. Circulating monocytes that respond to dietary lipids and chemokines and produce cytokines are the primary source of recruited adipose tissue macrophages (ATMs). In this study, we investigated sexual dimorphism in biological pathways in HFD-fed ATMs from male and female mice by RNA-seq. We also conducted chemotaxis assays to investigate sex differences in the migration of monocytes isolated from bone marrow from male and female mice toward a dietary saturated lipid — palmitate (PA), and a chemokine — monocyte chemoattractant protein 1 (MCP1), factors known to stimulate myeloid cells in obesity. ATM RNA-Seq demonstrated sex differences of both metabolic and inflammatory activation, including pathways for chemokine signaling and leukocyte trans-endothelial migration. In vivo monocyte transfer studies demonstrated that male monocytes traffic to female adipose tissue to generate ATMs more readily. In chemotaxis assays, lean male monocytes migrated in greater numbers than females toward PA and MCP1. With short-term HFD, male and female monocytes migrated similarly, but in chronic HFD, male monocytes showed greater migration than females upon PA and MCP1 stimulation. Studies with monocytes from toll-like receptor 4 knockout mice (Tlr4-/-) demonstrated that both males and females showed decreased migration than WT in response to PA and MCP1 implying a role for TLR4 in monocyte influx in response to meta-inflammation. Overall, these data demonstrate the role of sexual dimorphism in monocyte recruitment and response to metabolic stimuli that may influence meta-inflammation in obesity.

Aging, like obesity, is associated with metabolic and inflammatory alterations within adipose tissue in older individuals. Younger females are protected from adipose inflammation, but older post-menopausal females exhibit exaggerated visceral adiposity correlated with increased disease risk. Obesity accelerates the onset and progression of age-associated diseases, but it is unclear if aging and obesity drive adipose tissue dysfunction in a sexually dimorphic fashion. We investigated adipose tissue metabolism and inflammation in a diet-induced obesity model in young and old mice. We identified age related sex differences in adipose tissue macrophages (ATMs), fibrosis and lipid metabolism in male and female visceral fat depot (GWAT). Although aging normalized body weights between the sexes, females remained protected from proinflammatory ATMs and stimulated lipolysis failed to adversely affect the inflammatory state even with obesity. Older obese males had augmented CD11c+ ATMs and higher insulin levels, while females showed increased visceral adiposity and exaggerated Pparγ, and Pgc1α expression. Obesity in aging demonstrated similar expression of GWAT p53, p16, p21, Timp1 and Tgfβ1 in both sexes. Our studies suggest that even with aging, female GWAT shows an attenuated inflammatory response compared to males due to an efficient oxidative metabolism combined with an active tissue remodeling state.

Obesity-induced chronic inflammation is associated with metabolic disease. Results from mouse models utilizing a high-fat diet (HFD) have indicated that an increase in activated macrophages, including CD11c+ adipose tissue macrophages (ATMs), contributes to insulin resistance. Obesity primes myeloid cell production from hematopoietic stem cells (HSCs) and Toll-like receptor 4 (TLR4), and the downstream TIR domain-containing adapter protein-inducing interferon-β (TRIF)- and MyD88-mediated pathways regulate production of similar myeloid cells after lipopolysaccharide stimulation. However, the role of these pathways in HFD-induced myelopoiesis is unknown. We hypothesized that saturated fatty acids and HFD alter myelopoiesis by activating TLR4 pathways in HSCs, differentially producing pro-inflammatory CD11c+ myeloid cells that contribute to obesity-induced metabolic disease. Results from reciprocal bone marrow transplants (BMTs) with Tlr4-/- and WT mice indicated that TLR4 is required for HFD-induced myelopoiesis and production of CD11c+ ATMs. Experiments with homozygous knockouts of Irakm (encoding a suppressor of MyD88 inactivation) and Trif in competitive BMTs revealed that MyD88 is required for HFD expansion of granulocyte macrophage progenitors and that Trif is required for pregranulocyte macrophage progenitor expansion. A comparison of WT, Tlr4-/-, Myd88-/-, and Trif-/- mice on HFD demonstrated that TLR4 plays a role in the production of CD11c+ ATMs, and both Myd88-/- and Trif-/- mice produced fewer ATMs than WT mice. Moreover, HFD-induced TLR4 activation inhibited macrophage proliferation, leading to greater accumulation of recruited CD11c+ ATMs. Our results indicate that HFD potentiates TLR4 and both its MyD88- and TRIF-mediated downstream pathways within progenitors and adipose tissue and leads to macrophage polarization.

Men have a statistically higher risk of metabolic and cardiovascular disease than premenopausal women, but the mechanisms mediating these differences are elusive. Chronic inflammation during obesity contributes to disease risk and is significantly more robust in males. Prior work demonstrated that compared with obese males, obese females have reduced proinflammatory adipose tissue macrophages (ATMs). Given the paucity of data on how sex hormones contribute to macrophage responses in obesity, we sought to understand the role of sex hormones in promoting obesity-induced myeloid inflammation. We used gonadectomy, estrogen receptor–deficient alpha chimeras, and androgen-insensitive mice to model sex hormone deficiency. These models were evaluated in diet-induced obesity conditions (high-fat diet [HFD]) and in vitro myeloid assays. We found that ovariectomy increased weight gain and adiposity. Ovariectomized females had increased ATMs and bone marrow myeloid colonies compared with sham-gonadectomized females. In addition, castrated males exposed to HFD had improved glucose tolerance, insulin sensitivity, and adiposity with fewer Ly6chi monocytes and bone marrow myeloid colonies compared with sham-gonadectomized males, although local adipose inflammation was enhanced. Similar findings were observed in androgen-insensitive mice; however, these mice had fewer CD11c+ ATMs, implying a developmental role for androgens in myelopoiesis and adipose inflammation. We concluded that gonadectomy results in convergence of metabolic and inflammatory responses to HFD between the sexes, and that myeloid estrogen receptor alpha contributes minimally to diet-induced inflammatory responses, whereas loss of androgen-receptor signaling improves metabolic and inflammatory outcomes. These studies demonstrate that sex hormones play a critical role in sex differences in obesity, metabolic dysfunction, and myeloid inflammation.

With the increasing prevalence of obesity in women of reproductive age there is a need to understand the ramifications of this on offspring. The purpose of this study is to investigate the programming effects of maternal obesity during preconception and the preconception/gestational period on adiposity and adipose tissue inflammation in offspring using an animal model. Adult female C57Bl/6J mice were assigned either normal diet, high fat diet (HFD) prior to pregnancy, or HFD prior to and through pregnancy. Some offspring were maintained on normal diet while others started HFD later in life. Offspring were assessed for body composition and metabolic responses. Lipid storing tissues were evaluated for expansion and inflammation. Male offspring from the preconception group had the greatest weight gain, most subcutaneous adipose tissue, and largest liver mass when introduced to postnatal HFD. Male offspring of the preconception/gestation group had worsened glucose tolerance and an increase in resident (CD11c−) adipose tissue macrophages (ATMs) when exposed to postnatal HFD. Female offspring had no significant difference in any parameter between the diet treatment groups. In conclusion, this study demonstrates that prenatal and pregnancy windows have independent programming effects on offspring. Preconception exposure affects body composition and adiposity while gestation exposure affects metabolism and tissue immune cell phenotypes.

Objective: We aimed to examine if myeloid leukocyte profiles are associated with metabolic impairment in children and adolescents with obesity, and if sex, age, or race influence this relationship.Methods: 282 children ages 8–17 were evaluated. Predictor measures were absolute neutrophil counts (ANC), absolute monocyte count, monocyte subtypes and C reactive protein (CRP). Outcome variables were waist circumference, fasting glucose and insulin, HOMA-IR, HbA1c (%) and lipid profiles. Pearson correlation coefficients were used to determine associations between predictor and outcome variables. Wilcoxon two-sample tests were used to evaluate differences by sex.Results: CRP (p < 0.0001), ANC (p < 0.0018), and classical monocytes (p = 0.05) were significantly higher in children with obesity. CRP, ANC and classical monocytes showed positive correlations with waist circumference, insulin, HOMA-IR and triglycerides. CRP was positively associated with ANC overall (p = 0.05). ANC demonstrated positive correlation with monocytes (p < 0.001). The associations between predictor and outcome variables were influenced by sex, race, and age.Conclusions: CRP and myeloid leukocyte populations, specifically classical monocytes and neutrophils associate with both body composition and metabolic parameters in children with obesity suggesting that these cells may play a critical role in metabolic impairment. Race, gender and age interactions between monocytes and metabolic parameters were significant.

Background Weight loss by surgery or lifestyle changes is strongly recommended for obese individuals to improve metabolic health, but the underlying impairments that persist from a history of obesity remain unclear. Recent investigations demonstrate a persistent inflammatory state with weight loss and bariatric surgery, but the mechanism and impact are not fully understood. Additionally, these studies have not been performed in females although women are the majority of individuals undergoing weight loss interventions. Methods The goal of this study was to determine the sex differences in metabolically induced inflammation after dietary weight loss (WL) or bariatric surgery. Following a 60% high-fat diet (HFD) for 12 weeks, C57Bl/6j mice underwent either a dietary switch to normal chow for WL or vertical sleeve gastrectomy (VSG) and were evaluated 8 weeks after intervention. WL effects on myelopoiesis were further evaluated with bone marrow chimeras. Results Both sexes had a decrease in adiposity and total weight following WL or VSG intervention. With HFD, females had very little inflammation and no further increase with WL, but males had persistent inflammation even after WL despite metabolic improvement. Interestingly, after VSG, myeloid inflammation was increased in the livers of males and to a lesser extent in females. Conclusions These studies demonstrate that regardless of sex, it is critical to assess an individuals’ history of obesity rather than just rely on current weight status in medical decision-making. There are long-lasting effects on tissue inflammation in both sexes especially with surgical weight loss. Dietary change is overall most effective to improve meta-inflammation in obese males on its own or in combination with surgical weight loss.

Obesity is a global health epidemic, closely associated with cardiovascular diseases (CVD), hypertension, type 2 diabetes, and atherosclerosis. Obese adipose tissue is a site and source for inflammation that is strongly associated with these metabolic diseases. In obese mice models, males exhibit profound adipose tissue macrophage (ATM) accumulation in gonadal white adipose tissue (GWAT) linked to insulin resistance, while females are protected even with enhanced adiposity. This dampened inflammation may directly explain reduced metabolic and cardiovascular disease in young women. However, it is not clear what metabolic and inflammatory responses occur in post-menopausal models. We hypothesized an increased inflammatory response would occur in obese older females. We challenged male and female C57Bl6/j mice to 16-24 weeks of 60% high fat diet (HFD) starting at 6 weeks of age (young) or 10 month of age (old). Animal body weights and metabolic depot (adipose and liver) weights were measured at the completion of diet challenge. Flow cytometry was used to determine ATM populations in visceral (GWAT) compared to subcutaneous inguinal WAT (IWAT). Lipolysis was stimulated with a beta3 adrenergic receptor (ADRB3) agonist CL-316, 243 and free fatty acids (FFA), glycerol, and triglyceride (TG) levels assessed in serum and liver. Obesity in young mice led to fat accumulation in GWAT and IWAT of both males and females. In old male animals, fat pads did not expand, and liver weights were as a result larger than in females. Both young and old females had reduced adipose inflammation compared to males. ADRB3 activation had no effect on adipose tissue weights but significantly increased liver weights in obese young females. Obese CL treated young and old female mice showed elevated FFA compared to levels induced in males. Lipolysis promoted appearance of crown like structures (CLS) in both obese young and old males and females, due to CD11c- ATM accumulation. Obesity during aging continues to lead to enhanced inflammation in males along with steatosis but females continue to be protected with appropriate storage of fatty acids with very little induced inflammation. Sex differences in inflammation that persist in aging demonstrate that differences in meta-inflammation may explain sex differences in metabolic and cardiovascular diseases regardless of age and need to be further explored for targeted treatment strategies.

Males are known to have profound adipose tissue macrophage (ATM) accumulation in gonadal white adipose tissue (GWAT) during obesity, whereas females are protected from such an inflammatory response even with increased adiposity. The inflammatory tone in males is linked to insulin resistance and might be the underlying cause for sex differences in metabolic disease. Factors regulating the meta-inflammatory response remain unclear but enhanced lipid storage in females may explain the reduced inflammatory response to high-fat diets. In this study, we evaluated lean and obese females with stimulated lipolysis to understand whether a stress release of free fatty acids (FFAs) could induce female ATMs. We demonstrate that in both lean and obese females, GWAT CD11c(−) resident ATMs accumulate with β-3 adrenergic receptor–stimulated lipolysis. Lipolysis elevated serum FFA, triglyceride, and IL-6 levels in females that corresponded to significant phosphorylated hormone-sensitive lipase and adipose triglyceride lipase protein expression in obese female GWAT compared with males. Increased lipolytic response in obese females was associated with crown-like structures and induced Il6, Mcp1, Arg1, and Mgl1 expression in obese female GWAT, suggesting an environment of lipid clearance and adipose remodeling. With this finding we next investigated whether lipid storage and lipolytic mediators differed by sex. Diacylglycerol, ceramides, phospholipids, and certain fatty acid species associated with inflammation were elevated in male GWAT compared with obese female GWAT. Overall, our data demonstrate a role for GWAT lipid storage and lipolytic metabolites to induce inflammation in males and induce remodeling in females that might explain sex differences in overall metabolic health.

Men have a higher risk of metabolic and cardiovascular disease than pre-menopausal women, but the mechanisms of these differences are elusive. Chronic myeloid inflammation during obesity contributes to metabolic disease risk and is significantly more robust in males. Given the paucity of data on male sex hormones contributing to macrophage responses in obesity, our objective was to understand the role of androgens in promoting obesity-induced myeloid inflammation. Male and female C57Bl/6J mice were fed a 60% high fat diet for 24 weeks. Glucose tolerance and insulin sensitivity were measured. Monocyte transfer experiments assessed sex differences in bone marrow myeloid responses to obesity independent of host sex. Gonadectomy, mice deficient of androgen receptor signaling (ARtfm) and monocyte specific androgen receptor (AR) knockout mice (LysMAR-/y) were used to model androgen deficiency. Compared to males, females had dampened inflammatory responses with reduced CD11c+ ATMs and cytokines, even with increased adiposity. RNASeq demonstrated sex differences in gene pathways of both metabolic and inflammatory activation in ATMs. Male monocytes transferred into females remained primed for pro-inflammatory response and induced an increase in adiposity. Castrated males exposed to high fat diet had impaired glucose tolerance and increased insulin sensitivity with increased adiposity and lower numbers of CD11c+ ATMs. These same findings were seen in ARtfm mice. Testosterone enhanced palmitate-stimulated myeloid colony production, and this response was dampened in castrated, ARtfm, and LysMAR-/y mice. These studies demonstrate that androgens play a critical role in enhanced metabolic dysfunction and enhanced myeloid inflammation in response to obesogenic cues. Androgen driven myeloid inflammation leads to metabolic dysfunction in a cell-autonomous manner driving sex-differences in obesity induced meta-inflammation. Disclosure C.A. Griffin: None. S. Abrishami: None. M. Varghese: None. K. Singer: None.

Men and post-menopausal women are at greater risk for cardiovascular diseases and diabetes than younger women. In obese rodent models, males exhibit profound adipose tissue macrophage (ATM) accumulation in gonadal white adipose tissue (GWAT) linked to insulin resistance, while females are protected even with enhanced adiposity. We hypothesize that these inflammatory differences may be a result of altered lipolysis responses and that females would have enhanced ATM accumulation when lipolysis is induced. Lipolysis was stimulated with a beta3 adrenergic receptor (ADRB3) agonist CL-316, 243 in C57Bl6/j male and female mice fed 16 weeks of 60% high fat diet (HFD). GWAT leukocytes were isolated after 18 h and evaluated by flow cytometry. Lipogenic, lipolytic, oxidative and inflammatory gene expression along with immunofluorescence were performed. ADRB3 activation did not alter adipose tissue weights, but significantly reduced liver weights in obese females. Obese CL treated female mice showed elevated serum free fatty acid (FFA) and triglyceride (TG) levels compared to levels induced in males. Lipid overload impaired TG storage and utilization genes- Lpl, Fasn, Acsl1, Hsl, and Glut4 expression in obese females. Lipolysis promoted appearance of crown like structures (CLS) in males and females but only induced Il6 proinflammatory cytokine and Mcp1 chemokine expression in obese female GWAT. Activated lipolysis triggered CD11c- ATM accumulation in lean females but in both obese male and female GWAT. Obese males showed a marked reduction in GWAT dendritic cells (DC) but a significant reduction in both GWAT and inguinal WAT DCs of obese females. While obese females are resistant to inflammation, this study shows that induced lipolysis elevates FFA levels, alters lipid metabolism and increased CD11c- ATMs and CLSs in obese females. Elucidating the link between lipolysis and inflammation can better explain sex differences in overall metabolic health leading to targeted treatment strategies. Disclosure M. Varghese: None. S. Abrishami: None. K. Singer: None.

Obesity-induced chronic inflammation is associated with metabolic disease. Results from mouse models utilizing a high-fat diet (HFD) have indicated that an increase in activated macrophages, including CD11c(+) adipose tissue macrophages (ATMs), contributes to insulin resistance. Obesity primes myeloid cell production from hematopoietic stem cells (HSCs) and Toll-like receptor 4 (TLR4), and the downstream TIR domain–containing adapter protein–inducing interferon-β (TRIF)- and MyD88-mediated pathways regulate production of similar myeloid cells after lipopolysaccharide stimulation. However, the role of these pathways in HFD-induced myelopoiesis is unknown. We hypothesized that saturated fatty acids and HFD alter myelopoiesis by activating TLR4 pathways in HSCs, differentially producing pro-inflammatory CD11c(+) myeloid cells that contribute to obesity-induced metabolic disease. Results from reciprocal bone marrow transplants (BMTs) with Tlr4(−/−) and WT mice indicated that TLR4 is required for HFD-induced myelopoiesis and production of CD11c(+) ATMs. Experiments with homozygous knockouts of Irakm (encoding a suppressor of MyD88 inactivation) and Trif in competitive BMTs revealed that MyD88 is required for HFD expansion of granulocyte macrophage progenitors and that Trif is required for pregranulocyte macrophage progenitor expansion. A comparison of WT, Tlr4(−/−), Myd88(−/−), and Trif(−/−) mice on HFD demonstrated that TLR4 plays a role in the production of CD11c(+) ATMs, and both Myd88(−/−) and Trif(−/−) mice produced fewer ATMs than WT mice. Moreover, HFD-induced TLR4 activation inhibited macrophage proliferation, leading to greater accumulation of recruited CD11c(+) ATMs. Our results indicate that HFD potentiates TLR4 and both its MyD88- and TRIF-mediated downstream pathways within progenitors and adipose tissue and leads to macrophage polarization.

Overnutrition during critical windows of development plays a significant role in life-long metabolic disease risk. Early exposure to excessive nutrition may result in altered programming leading to increased susceptibility to obesity, inflammation, and metabolic complications. This study investigated the programming effects of high-fat diet (HFD) exposure during the lactation period on offspring adiposity and inflammation. Female C57Bl/6J dams were fed a normal diet or a 60% HFD during lactation. Offspring were weaned onto a normal diet until 12 weeks of age when half were re-challenged with HFD for 12 weeks. Metabolic testing was performed throughout adulthood. At 24 weeks, adipose depots were isolated and evaluated for macrophage profiling and inflammatory gene expression. Males exposed to HFD during lactation had insulin resistance and glucose intolerance as adults. After re-introduction to HFD, males had increased weight gain and worsened insulin resistance and hyperglycemia. There was increased infiltration of pro-inflammatory CD11c+ adipose tissue macrophages, and bone marrow was primed to produce granulocytes and macrophages. Bone density was lower due to enhanced marrow adiposity. This study demonstrates that maternal HFD exposure during the lactational window programs offspring adiposity, inflammation, and impaired glucose homeostasis.

Diet-induced obesity is associated with an infiltration of monocytes into the adipose tissue in male mouse models. These monocytes differentiate into inflammatory macrophages that drive insulin resistance. This increase in circulating monocytes originates in the bone marrow (BM) where hematopoietic stem cells (HSC) and myeloid-restricted progenitors (GMPs and PreGMs) expand. HSCs isolated from BM of male mice on high-fat diet (HFD) for 16 weeks show myeloid lineage skewing that lasts through successive bone marrow transplants (BMT). This suggests that HFD induces changes to the HSC niche - a multicellular structure that produces regulatory signals that are critical for maintaining the HSC pool. While BM adipocytes expand with HFD exposure, the niche cells promoting myelopoiesis with HFD are unknown. We chose to investigate two cell populations that have been implicated in driving myelopoiesis in other conditions; the BM endothelial cell (BMEC), a critical HSC niche cell, and neutrophils. We hypothesize that HFD induces HSC expansion and reprogramming through neutrophil-BMEC communication. Using 60% HFD in C57Bl/6J mice we evaluated circulating and BM neutrophils and Ly6C monocytes; HSCs and progenitors, and BMECs during short- and long-term HFD exposure. We found that as early as 24 hours after mice went on HFD there is a significant spike in circulating mature neutrophils that return to normal levels by 72 hours only to expand again by 16 weeks HFD. Ly6Chi monocytes rose only after 1 month of HFD exposure. BMECs do not appear to be altered in number with HFD in short- or long-term assays. Further qualitative analysis of BMECs, MAT, and neutrophils are necessary to determine which cells are critical for regulating the HSC niche in HFD.

OBJECTIVE: Gram-negative septic shock has a clinical mortality rate approaching 50%. The cause of death is secondary to a systemic inflammatory response syndrome with resulting cardiovascular collapse, ischemic damage to vital organs, and multiple-organ systems failure. Renal tubule cell injury occurs early in septic shock but is not clinically appreciated. Since renal tubule cells appear to play a critical role in the immunoregulation of stress states, renal cell therapy during septic shock may alter the detrimental multiple-organ consequences of systemic Gram-negative infection. The development of a tissue-engineered bioartificial kidney consisting of a conventional hemofiltration cartridge in series with a renal tubule assist device (RAD) containing 109 renal proximal tubule cells may be a new therapeutic approach to this clinical disorder. DESIGN: Laboratory study. SETTING: University medical school. SUBJECTS: Pigs weighing 30-35 kg. INTERVENTIONS: To assess the effect of the bioartificial kidney and the RAD in septic shock, pigs were administered 30 x 10(10) bacteria/kg body weight of Escherichia coli into the peritoneal cavity and within 1 hr were immediately placed in a continuous venovenous hemofiltration extracorporeal circuit with either a sham RAD without cells or a RAD with cells. MEASUREMENTS AND MAIN RESULTS: In this animal model, septic shock resulted within hours in acute tubule necrosis in the kidneys of all animals. Renal cell therapy resulted in significantly higher cardiac outputs and renal blood flow rates in treated animals compared with sham controls. RAD treatment also was associated with significantly lower plasma circulating concentrations of interleukin-6 and interferon-gamma compared with sham-treated animals. IL-6 release rates from peripheral blood mononuclear cells isolated from RAD-treated animals were significantly higher after endotoxin stimulation than those isolated from control animals. These physiologic and molecular alterations were associated with nearly a doubling of the average survival time in the RAD-treated group compared with the sham control group. CONCLUSION: These results demonstrate that renal cell therapy ameliorates cardiac and vascular dysfunction, alters systemic cytokine abnormalities, and improves survival time in a large animal model of Gram-negative septic shock. A cell therapeutic approach with a tissue-engineered bioartificial kidney may be a new treatment modality for this current unmet medical need.

The bioartificial kidney (BAK) consists of a conven- tional hemofiltration cartridge in series with a renal tubule assist device (RAD) containing 10 9 porcine renal proximal tubule cells. BAK replaces filtration, transport, and metabolic and endocrinologic activities of a kidney. Previous work in an acutely uremic dog model demonstrated that BAK ameliorated endotoxin (lipopolysaccharide (LPS))-induced hypotension and altered plasma cytokine levels. To further assess the role of BAK in sepsis in acute renal failure, dogs were nephrecto- mized and 48 h later administered intraperitoneally with 30 10 10 bacteria/kg of E. coli. One hour after bacterial adminis- tration, animals were placed in a continuous venovenous he- mofiltration circuit with either a sham RAD without cells (n 6) or a RAD with cells (n 6). BP, cardiac output, heart rate, pulmonary capillary wedge pressure, and systemic vascular resistance were measured throughout the study. All animals tested were in renal failure, with blood urea nitrogen and serum creatinine concentrations greater than 60 and 6 mg/dl, respec- tively. RAD treatment maintained significantly better cardio- vascular performance, as determined by arterial BP (P 0.05) and cardiac output (P 0.02), for longer periods than sham RAD therapy. Consistently, all sham RAD-treated animals, except one, expired within 2 to 9 h after bacterial administra- tion, whereas all RAD-treated animals survived more than 10 h. Plasma levels of TNF-, IL-10, and C-reactive protein (CRP) were measured during cell RAD and sham RAD treat- ment. IL-10 levels were significantly higher (P 0.01) during the entire treatment interval in the RAD animals compared with sham controls. These data demonstrated in a pilot large animal experiment that the BAK with RAD altered plasma cytokine levels in acutely uremic animals with septic shock. This change was associated with improved cardiovascular per- formance and increased survival time. These results demon- strate that the addition of cell therapy to hemofiltration in an acutely uremic animal model with septic shock ameliorates cardiovascular dysfunction, alters systemic cytokine balance, and improves survival time.