Vasodilator Dysfunction in Human Obesity: Established and Emerging Mechanisms.

ABSTRACT: Human obesity is associated with insulin resistance and often results in a number of metabolic abnormalities and cardiovascular complications. Over the past decades, substantial advances in the understanding of the cellular and molecular pathophysiological pathways underlying the obesity-related vascular dysfunction have facilitated better identification of several players participating in this abnormality. However, the complex interplay between the disparate mechanisms involved has not yet been fully elucidated. Moreover, in medical practice, the clinical syndromes stemming from obesity-related vascular dysfunction still carry a substantial burden of morbidity and mortality; thus, early identification and personalized clinical management seem of the essence. Here, we will initially describe the alterations of intravascular homeostatic mechanisms occurring in arteries of obese patients. Then, we will briefly enumerate those recognized causative factors of obesity-related vasodilator dysfunction, such as vascular insulin resistance, lipotoxicity, visceral adipose tissue expansion, and perivascular adipose tissue abnormalities; next, we will discuss in greater detail some emerging pathophysiological mechanisms, including skeletal muscle inflammation, signals from gut microbiome, and the role of extracellular vesicles and microRNAs. Finally, it will touch on some gaps in knowledge, as well as some current acquisitions for specific treatment regimens, such as glucagon-like peptide-1 enhancers and sodium-glucose transporter2 inhibitors, that could arrest or slow the progression of this abnormality full of unwanted consequences.

Fetal growth restriction is a host specific response to infection with an impaired spiral artery remodeling-inducing strain of Porphyromonas gingivalis.

Porphyromonas gingivalis is a periodontal pathogen implicated in a range of pregnancy disorders that involve impaired spiral artery remodeling (ISAR) with or without fetal growth restriction (FGR). Using a rodent periodontitis model, we assessed the ability of P. gingivalis to produce ISAR and FGR in Sprague Dawley (SD) and Wistar (WIS) rats. Both infected SD and WIS rats developed ISAR, but only WIS rats developed FGR despite both rat strains having equivalent microbial loads within the placenta. Neither maternal systemic inflammation nor placental (fetal) inflammation was a feature of FGR in WIS rats. Unique to infected WIS rats, was loss of trophoblast cell density within the junctional zone of the placenta that was not present in SD tissues. In addition, infected WIS rats had a higher proportion of junctional zone trophoblast cells positive for cytoplasmic high temperature requirement A1 (Htra1), a marker of cellular oxidative stress. Our results show a novel phenomenon present in P. gingivalis-induced FGR, with relevance to human disease since dysregulation of placental Htra1 and placental oxidative stress are features of preeclamptic placentas and preeclampsia with FGR.

A Cardiovascular Disease-Linked Gut Microbial Metabolite Acts via Adrenergic Receptors.

Using untargeted metabolomics (n = 1,162 subjects), the plasma metabolite (m/z = 265.1188) phenylacetylglutamine (PAGln) was discovered and then shown in an independent cohort (n = 4,000 subjects) to be associated with cardiovascular disease (CVD) and incident major adverse cardiovascular events (myocardial infarction, stroke, or death). A gut microbiota-derived metabolite, PAGln, was shown to enhance platelet activation-related phenotypes and thrombosis potential in whole blood, isolated platelets, and animal models of arterial injury. Functional and genetic engineering studies with human commensals, coupled with microbial colonization of germ-free mice, showed the microbial porA gene facilitates dietary phenylalanine conversion into phenylacetic acid, with subsequent host generation of PAGln and phenylacetylglycine (PAGly) fostering platelet responsiveness and thrombosis potential. Both gain- and loss-of-function studies employing genetic and pharmacological tools reveal PAGln mediates cellular events through G-protein coupled receptors, including α2A, α2B, and ß2-adrenergic receptors. PAGln thus represents a new CVD-promoting gut microbiota-dependent metabolite that signals via adrenergic receptors.

Oral-bacterial-induced arterial and venous thrombus in rats: Pathological and immunological studies.

Objectives: Our study investigated the pathological outcome of experimental thrombi that incorporate oral bacteria. Material and methods: A small artery and vein in the rats' groins were injected with a solution containing periodontal bacteria Porphyromonas gingivalis and followed up for 28 days. In all, 18 limbs of nine male rats (500-650 g) were used for the arterial study, and eight limbs of four rats were used for the veins. Two densities of the bacterial solution and two arterial thicknesses sizes were used in the arterial study. Both proximal and distal arteries and veins were ligated loosely using a monofilament nylon suture before bacterial suspensions or control solutions were injected into the ligated vessels. Results: After 7, 14-18, and 28 days, the rats were sacrificed. Pathology and immunohistochemistry were performed. All specimens exhibited thrombus formation and an acute inflammation reaction with granulocytes at 7 days and then settled down to chronic fibrous change with plasma cells or macrophages at 28 days in the arterial thrombus. CD3 (Pan T-cells), CD79a (Pan B cells in the rats), and IgG were observed in the process of the healing of the arterial thrombus. Venous changes showed relatively clear recanalization that appeared at 7 days, which is slightly different from the artery. Granulocytes were present from 7 to 28 days. Conclusions: Periodontal bacteria act as an inflammatory core in the vessels, but not as an infectious agent, in our experiments, because of their low ability to invade tissues.

Cryopreserved Venous Allografts in Supra-inguinal Reconstructions: A Single Centre Experience.

OBJECTIVE: This study introduces a novel technique for supra-inguinal arterial reconstructions with cryopreserved femoral vein and caval allografts with a low re-infection rate and an acceptable graft re-intervention rate on early mid term analysis. METHODS: Patients treated from February 2012 to March 2018 with cryopreserved venous allograft reconstructions owing to infection in the supra-inguinal area were reviewed retrospectively. The primary end points were re-infection and the treatment related mortality rate. Secondary end points were 30 and 90 day and overall mortality and graft re-intervention rate. RESULTS: Of the 23 patients treated with cryopreserved venous allografts for infection in aorto-iliac area, 21 (91%) patients underwent reconstruction with cryopreserved femoral veins and two (9%) with vena cava. Indications for treatment were aortic graft infections (n = 12 [52%]), mycotic aneurysms (n = 5 [22%]), femorofemoral prosthetic infections (n = 3 [13%]), anastomotic pseudo-aneurysms (n = 2 [9%]), and aortic thrombosis with intestinal spillage (n = 1 [4%]). In hospital and 90 day mortality were 9% (n = 2); overall treatment related mortality during the median follow up of 15 months was 13% (n = 3). During the follow up, two allografts were re-operated on owing to anastomotic dilatation and one because of re-infection, resulting in a re-intervention rate of 13% (n = 3). None of the grafts was lost and there were no amputations. At the end of follow up 17 patients (74%) were alive. Kaplan-Meier estimation for survival was 76% (95% confidence interval [CI] 57%-95%) at one year and 70% (95% CI 49%-91%) at two years. CONCLUSION: Cryopreserved venous allografts appear to be an infection resistant and reasonably safe reconstruction material in the aorto-iliac axis based upon the early mid term analysis from a single centre experience. Further research is needed to compare their performance with other biological reconstruction material.

The gut microbiome and cardiovascular disease: current knowledge and clinical potential.

Cardiovascular disease (CVD) is the leading cause of death worldwide. The human body is populated by a diverse community of microbes, dominated by bacteria, but also including viruses and fungi. The largest and most complex of these communities is located in the gastrointestinal system and, with its associated genome, is known as the gut microbiome. Gut microbiome perturbations and related dysbiosis have been implicated in the progression and pathogenesis of CVD, including atherosclerosis, hypertension, and heart failure. Although there have been advances in the characterization and analysis of the gut microbiota and associated bacterial metabolites, the exact mechanisms through which they exert their action are not well understood. This review will focus on the role of the gut microbiome and associated functional components in the development and progression of atherosclerosis. Potential treatments to alter the gut microbiome to prevent or treat atherosclerosis and CVD are also discussed.

Systematic Review and Meta-Analysis on the Management of Open Abdominal Aortic Graft Infections.

OBJECTIVE: Aortic graft infection (AGI) is a disastrous complication with an incidence of 0.2-6% in operated patients. With little or no high quality evidence, the best treatment option remains unclear. Therefore, the literature on the management of open abdominal AGI was systematically reviewed to determine optimal treatment. METHODS: In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a systematic review and meta-analysis was conducted for AGI. MEDLINE, Embase, and the Cochrane Database of Systematic Reviews were searched. Methodological quality was assessed using the Methodological Index for Non-randomised Studies (MINORS) score. Primary outcomes were 30 day mortality and one year survival. Secondary outcomes were survival, infection recurrence, limb salvage, and graft patency. RESULTS: Of 1574 studies identified, 32 papers were included in the study. The overall quality of the studies was moderate, with an average MINORS score of 11.9. Pooled overall 30 day mortality and one year survival were 13.5% (95% CI 10.5-16.4) and 73.6% (95% CI 68.8-78.4), respectively. The lowest 30 day mortality and highest one year survival were found for in situ repair compared with extra-anatomic repair and for prosthetic grafts compared with venous grafts or arterial allografts. The infection recurrence rate was highest for prosthetic grafts. CONCLUSIONS: There is a lack of well designed, qualitative comparative studies making conclusive recommendations impossible. The current best available data suggests that partial graft removal should be avoided and the lowest 30 day mortality and best one year survival are achieved with in situ repair using prosthetic grafts. Initiatives such as the MAGIC database to collaboratively collect prospective data are an important step forward in obtaining more solid answers on this topic.

Postmortem Retrieval of Arterial Allografts: Preliminary Results.

BACKGROUND: Cryopreserved arterial allografts are vascular substitutes used for arterial reconstructions in a septic field. Their use remains however limited by the shortage of donors. One of the possibilities to address this lack of grafts is to multiply the sources of retrieval. The objective of this preliminary study was the evaluation of the early clinical results and the microbiological safety of arterial grafts retrieved after death. METHODS: In addition to the standard conditions of arterial sampling, the criteria of inclusion for postmortem retrieval comprised the refrigeration of the body of the donor within 4 hr following the death, a 24-hr time limit from the death, and the availability of an adapted place for retrieval (surgical unit or death chamber respecting the required aseptic conditions). We only retrieved the femoral axes (FAs) and the aortoiliac bifurcation. The conditions of retrieval, transportation, preparation, and conservation were identical to those of cryopreserved arterial allografts harvested during standard multiple organs retrieval. We evaluated the bacteriological risk of contamination and the patency of the grafts in the short and medium term. RESULTS: In 2015 and 2016, 6 donors were included. Eleven FAs and 2 aortic bifurcations were harvested. The bacteriological samples done on arrival in bank and after thawing were negative in the 6 donors, but one of the 6 donors presented a bacterial contamination of other removed tissues, and the arterial grafts obtained from this donor were destroyed as a precaution (3 grafts). The quality of the grafts evaluated by the surgeon during harvesting was good in all the cases. The indications of allografts were arterial reconstruction in a septic field (n = 8) and aorto-hepatic bypass during hepatic transplantation (n = 1). One graft was unhopefully thawed without being used. At the end of the follow-up, 8 out of 9 grafts were patent. Two ruptures occurred in a context of locally persistent sepsis (crural abscess due to Salmonella typhi and persistent groin wound disunion with a polymicrobial flora). One allograft thrombosis was observed (aorto-hepatic bypass for transplantation). These complications were unrelated to the mode of graft harvesting. No aneurysmal evolution was observed. CONCLUSIONS: The preliminary results of this protocol are encouraging because the immediate quality of the grafts was good with a risk of microbiological contamination identical with that of the usual harvesting mode. This mode of harvesting looks promising to reduce the shortage in arterial allografts and could be extended to harvest thoracic aortic allografts. However, results at a larger scale are necessary to confirm these data.

Bacterial signatures in thrombus aspirates of patients with lower limb arterial and venous thrombosis.

OBJECTIVE: Increasing data supports the role of bacterial inflammation in adverse events of cardiovascular and cerebrovascular diseases. In our previous research, DNA of bacterial species found in coronary artery thrombus aspirates and ruptured cerebral aneurysms were mostly of endodontic and periodontal origin, where Streptococcus mitis group DNA was the most common. We hypothesized that the genomes of S mitis group could be identified in thrombus aspirates of patients with lower limb arterial and deep venous thrombosis. METHODS: Thrombus aspirates and control blood samples taken from 42 patients with acute or acute-on-chronic lower limb ischemia (Rutherford I-IIb) owing to arterial or graft thrombosis (n = 31) or lower limb deep venous thrombosis (n = 11) were examined using a quantitative real-time polymerase chain reaction to detect all possible bacterial DNA and DNA of S mitis group in particular. The samples were considered positive, if the amount of bacterial DNA in the thrombus aspirates was 2-fold or greater in comparison with control blood samples. RESULTS: In the positive samples the mean difference for the total bacterial DNA was 12.1-fold (median, 7.1), whereas the differences for S mitis group DNA were a mean of 29.1 and a median of 5.2-fold. Of the arterial thrombus aspirates, 57.9% were positive for bacterial DNA, whereas bacterial genomes were found in 75% of bypass graft thrombosis with 77.8% of the prosthetic grafts being positive. Of the deep vein thrombus aspirates, 45.5% contained bacterial genomes. Most (80%) of bacterial DNA-positive cases contained DNA from the S mitis group. Previous arterial interventions were significantly associated with the occurrence of S mitis group DNA (P = .049, Fisher's exact test). CONCLUSIONS: This is the first study to report the presence of bacterial DNA, predominantly of S mitis group origin, in the thrombus aspirates of surgical patients with lower limb arterial and deep venous thrombosis, suggesting their possible role in the pathogenesis of thrombotic events. Additional studies will, however, be needed to reach a final conclusion.

The presence of periopathogenic bacteria in subgingival and atherosclerotic plaques - An age related comparative analysis.

INTRODUCTION: There is a known connection between periodontitis and atherosclerosis and the presence of periopathogens in blood vessels. However, changes of the oral microflora related to the aging process and its possible effects on atherosclerosis, have yet to be analyzed. The aim of this study was to assess temporal changes in the frequency of periodontal bacteria in the subgingival plaque and in atherosclerotic blood vessels of patients with atherosclerosis. METHODOLOGY: The study included 100 patients with atherosclerosis and periodontitis, divided into two groups, below and over 60 years of age. Clinical examinations were performedand subgingival plaque specimens were collected as well as biopsy specimens from the following arteries: coronary (34), carotid (29), abdominal (10), femoral (10), mammary (13) and iliac (4). Subgingival and artery specimens were subjected to PCR detection of 5 major periodontal pathogens: Porphyromonas gingivalis (Pg), Prevotella intermedia (Pi), Aggregatibacter actinomycetemcomitans (Aa), Tannerella forsythensis (Tf) and Treponema denticola (Td). RESULTS: Tf was the most and Td the least frequent bacteria in both age groups and in both types of samples. The frequencies of bacteria in subgingival versus atherosclerotic samples were: Tf (76%:53%), Pi (71%:31%), Pg (60%:38%), Aa (39%:14%) and Td (21%:6%). Only Aa and Pi showed a significant difference of prevalence between younger and older patients. The most colonized artery was a. coronaria, followed by a. carotis, a. abdominalis, a. mammaria, and a. femoralis. CONCLUSIONS: Patient's age and the distance of a given blood vessel from the oral cavity influenced microbiological findings in the atherotic plaque.

"In situ" endografting in the treatment of arterial and graft infections.

OBJECTIVE: Endografts (eg, aortic aneurysm device or covered stent) are increasingly being used to temporize or treat arterial and graft infections in inaccessible areas, in patients with compromised anatomy, or in the presence of active bleeding or rupture. This summary examines the evidence for "in situ" endografting in the treatment these conditions. METHODS: A two-level search strategy of the literature (MEDLINE, PubMed, Google Scholar, and The Cochrane Library) was performed for relevant articles listed between January 2000 and December 2015. The review was confined to patients with primary and secondary bacterial or viral arterial infections, with or without fistulization and infection of bypass grafts and arteriovenous accesses. For the purposes of this summary, endografts can be considered to be an aortic aneurysm device or a covered stent. RESULTS: There are no societal guidelines. Endografts have been successfully applied to mycotic arterial aneurysms, aortoenteric, aortobronchial, and arterioureteric fistulae, and to anastomotic bleeds secondary to infection. Multiple reports indicate success at the control of hemorrhage in all locations. Short-term outcomes are good, but fatal infection-related complications, especially if antibiotic therapy is halted, are well reported and necessitate a more definitive plan for the long term. CONCLUSIONS: Stent grafts remain an important and viable option for the treatment of mycotic aneurysms, aortoesophageal and aortobronchial fistulae, and infected pseudoaneurysms in anatomically or technically inaccessible locations. In patients with a short life span (<6 months), no further intervention is generally required. In patients with a predicted life span >6 months, careful consideration should be given to a more definitive procedure. Life-long appropriate antibiotic therapy is strongly recommended for any patient receiving an endograft in an infected field.

Absence of mycobacterial DNA in peripheral blood and artery specimens in patients with Takayasu arteritis.

The objective of this study was to demonstrate the presence of mycobacterial nucleic acid sequences in peripheral blood and arteries from patients with Takayasu arteritis (TA). Polymerase chain reaction was performed to detect mycobacterial DNA from three different nucleic acid sequences including the insertion sequence (IS) 6110, the 65-kDa heat shock protein gene (HSP65), and the 16S ribosomal RNA (rRNA) gene in peripheral blood from 32 TA patients and in arterial specimens from 10 TA patients. Twenty-eight HIV-negative patients with pulmonary tuberculosis prior to therapy were tested for IS6110 in peripheral blood as positive controls, and 24 blood donors were evaluated as healthy controls (HC). All TA patients were negative for the insertion sequence IS6110 and for HSP65 and 16S rRNA genes in blood samples and in arterial specimens. IS6110 sequence was found in peripheral blood from 22 (78.5 %) patients with pulmonary tuberculosis but not in HC. In conclusion, the strategy of mycobacterial-specific nucleic acid amplification in the peripheral blood and arterial specimens of TA patients was unable to lend support to the association between TA and tuberculosis long suggested in the literature.

Femoral vein repair of arterial infections: technical tips to reduce procedure time.

INTRODUCTION: Success with the neoaortoiliac system (NAIS) bypass has previously been reported. Drawbacks to this procedure include prolonged operative times and significant morbidity. The aim of this study was to evaluate whether a 2-team approach in addition to a consistent anastomosis technique reduces the operative time of the NAIS procedure. METHODS: A single-center retrospective review was performed for operations using femoral vein in arterial reconstruction from 2003 to 2012. RESULTS: A total of 40 patients, 25 men and 15 women, were included for analysis. Median operative time for all operations was 300 minutes (interquartile range). Thirty-day mortality was 7.5% (n = 3). Assisted primary patency at 1 year was 100%. CONCLUSION: A 2-surgical team approach can reduce the operative time by up to 50%. This improves the attractiveness of this procedure, particularly when recalling that the treatment is definitive by virtue of its eradication of the source of infection.

Evaluation of decontamination process of heart valve and artery tissues in European Homograft Bank (EHB): a retrospective study of 1,055 cases.

To evaluate the efficiency of decontamination practice in European Homograft Bank (EHB), the data of the cardiovascular tissues received during recent 2 years were retrospectively analysed in this study. After initial assessment, the tissues were incubated in a 3-antibiotics' cocktail at 4°C for 20-48 h. The states of contamination were evaluated before and after incubation with the focus on the differences in donor type, tissue type, germ type and incubation time. Amongst 1,055 eligible tissues, 77.2% were hearts and 22.8% were arteries. 82.2% of the tissues were retrieved from the multi-organ donors (MOD), 15.4% from the recipients of heart transplantation (RHT) and 2.4% from the non-heart beating donors (NHBD). The initial contamination rate was 27.4% with a significantly higher incidence in arteries. The RHT tissues had the lowest contamination rate comparing to that of MOD and NHBD. Staphylococcus species was the major source of contamination. After antibiotic incubation, 76.8% of the contaminated tissues were disinfected, which was significantly higher for the hearts than the arteries. The RHT tissues had the highest decontamination rate than that of MOD and NHBD tissues. Propionibacterium acnes was detected in 48.1% of the remaining contaminated cases. The average incubation time of the Propionibacterium-positive tissues was significantly shorter than that of decontaminated tissues. In conclusion, the current decontamination protocol of EHB is sufficient for most of the initially contaminated bacteria, whereas it is inadequate for Propionibacterium acnes. This may be related to the slow-growing nature of this bacterium and thereby the relative shorter antibiotic incubation time.

Does a species of Rickettsia play a role in the pathophysiology of Buerger's disease?

Rickettsia is an intracellular pathogen that attaches to vascular endothelial cell membranes and its genome integrates into the DNA of the host and thereby inhibits apoptosis of the endothelial cells. Rickettsia can infect the body following a flea/louse bite. Rickettsia was suggested as one etiology of Buerger's disease long ago. We report a patient with Buerger's disease for whom a left below-knee amputation was done. Twenty-five biopsies for DNA extraction were obtained from the arteries, veins and microvasculature of the amputated limb. Three samples were positive for Rickettsia. The finding may explain the proliferation of endothelial cells in the pathology of Buerger's disease, segmental nature of the disease, involving small- and medium-sized vessels, and the prevalence of Buerger's disease among the low socioeconomic class of the society. Understanding the infectious etiology of Buerger's disease would be invaluable, since early antibiotic therapy or even vaccination might have prevented the limb loss in the current and other cases of Buerger's disease. The authors suggest that paraffin blocks of Buerger's disease biopsies be investigated for Rickettsia infection, focusing specifically on the area of endothelial cell proliferation for DNA extraction. These results should be compared with other biopsies from a variety of other peripheral vascular diseases.

Pathogens and atherosclerosis: update on the potential contribution of multiple infectious organisms to the pathogenesis of atherosclerosis.

It is currently unclear what causes the chronic inflammation within atherosclerotic plaques. One emerging paradigm suggests that infection with bacteria and/or viruses can contribute to the pathogenesis of atherosclerosis either via direct infection of vascular cells or via the indirect effects of cytokines or acute phase proteins induced by infection at non-vascular sites. This paradigm has been supported by multiple epidemiological studies that have established positive associations between the risk of cardiovascular disease morbidity and mortality and markers of infection. It has also been supported by experimental studies showing an acceleration of the development of atherosclerosis following infection of hyperlipidaemic animal models. There are now a large number of different infectious agents that have been linked with an increased risk of cardiovascular disease. These include: Chlamydia pneumoniae, Porphyromonas gingivalis, Helicobacter pylori , influenza A virus, hepatitis C virus, cytomegalovirus, and human immunodeficiency virus. However, there are significant differences in the strength of the data supporting their association with cardiovascular disease pathogenesis. In some cases, the infectious agents are found within the plaques and viable organisms can be isolated suggesting a direct effect. In other cases, the association is entirely based on biomarkers. In the following review, we evaluate the strength of the data for individual or groups of pathogens with regard to atherosclerosis pathogenesis and their potential contribution by direct or indirect mechanisms and discuss whether the established associations are supportive of the infectious disease paradigm. We also discuss the failure of antibiotic trials and the question of persistent infection.

Endovascular treatment of a symptomatic mycotic aneurysm of the peroneal artery.

A 69-year-old man was referred to our facility owing to the sudden onset of a compression-like pain in the right leg, without limb-threatening acute ischemia. The duplex scan examination, followed by a selective leg angiography, showed the presence of a peroneal artery aneurysm. A diagnosis of mycotic aneurysm was made on the basis of the patient's clinical condition, positive blood cultures, and the unusual location of the lesion. Endovascular repair was performed by using a coil embolization and covered stent release. The patient was discharged in good general condition with complete pain relief. In previously published data, only four cases of peroneal artery aneurysm with a mycotic etiology have been reported. In this case, the endovascular treatment was safe and resolutive.

Trichosporon fungal arteritis causing rupture of vascular anastamosis after commercial kidney transplantation: a case report and review of literature.

This is a case report of a ruptured vascular anastomosis resulting from fungal arteritis in a commercial renal transplantation. The diagnosis was made quite early posttransplantation (at the 18th posttransplant day); this was proved by histopathologic examination and culture of the vessel wall,which showed Trichosporon fungal infection. The patient underwent operation for control of the bleeding and removal of the graft and of the diseased iliac vascular segment. On reviewing the literature, we found 17 reports of fungal arteritis in solid-organ transplant recipients; our case was the first one to report Trichosporon species as the causative agent. Infection could result from surgical or graft contamination or from preexistent infection in the patient. There is a consensus that the standard of care should include removal of the graft and the diseased iliac vascular segment with an appropriate vascular graft, because simple suturing of the disrupted infected anastomosis generally ends with disastrous recurrent rupture. A high index of suspicion is required to ensure both early diagnosis and appropriate treatment to prevent tragic loss of recipient life.

Phosphorylated dihydroceramides from common human bacteria are recovered in human tissues.

Novel phosphorylated dihydroceramide (PDHC) lipids produced by the periodontal pathogen Porphyromonas gingivalis include phosphoethanolamine (PE DHC) and phosphoglycerol dihydroceramides (PG DHC) lipids. These PDHC lipids mediate cellular effects through Toll-like receptor 2 (TLR2) including promotion of IL-6 secretion from dendritic cells and inhibition of osteoblast differentiation and function in vitro and in vivo. The PE DHC lipids also enhance (TLR2)-dependent murine experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis. The unique non-mammalian structures of these lipids allows for their specific quantification in bacteria and human tissues using multiple reaction monitoring (MRM)-mass spectrometry (MS). Synthesis of these lipids by other common human bacteria and the presence of these lipids in human tissues have not yet been determined. We now report that synthesis of these lipids can be attributed to a small number of intestinal and oral organisms within the Bacteroides, Parabacteroides, Prevotella, Tannerella and Porphyromonas genera. Additionally, the PDHCs are not only present in gingival tissues, but are also present in human blood, vasculature tissues and brain. Finally, the distribution of these TLR2-activating lipids in human tissues varies with both the tissue site and disease status of the tissue suggesting a role for PDHCs in human disease.