Acetate acts as a metabolic immunomodulator by bolstering T-cell effector function and potentiating antitumor immunity in breast cancer

Acetate metabolism is an important metabolic pathway in many cancers and is controlled by acetyl-CoA synthetase 2 (ACSS2), an enzyme that catalyzes the conversion of acetate to acetyl-CoA. While the metabolic role of ACSS2 in cancer is well described, the consequences of blocking tumor acetate metabolism on the tumor microenvironment and antitumor immunity are unknown. We demonstrate that blocking ACSS2, switches cancer cells from acetate consumers to producers of acetate thereby freeing acetate for tumor-infiltrating lymphocytes to use as a fuel source. We show that acetate supplementation metabolically bolsters T-cell effector functions and proliferation. Targeting ACSS2 with CRISPR-Cas9 guides or a small-molecule inhibitor promotes an antitumor immune response and enhances the efficacy of chemotherapy in preclinical breast cancer models. We propose a paradigm for targeting acetate metabolism in cancer in which inhibition of ACSS2 dually acts to impair tumor cell metabolism and potentiate antitumor immunity.

Alterations in bone metabolites with age in C57BL/6 mice model

Understanding the pathophysiology behind age-related diseases is an urgent need as the elderly population continues to grow. With age, there is a high risk of musculoskeletal deterioration and associated morbidity and mortality. Although the exact mechanism behind age-related degeneration is unknown, it is well established that alteration in cellular metabolism is one of the important contributing factors. Alteration in signaling pathways with age leads to the accumulation or depletion of several metabolites that play a vital role in musculoskeletal pathophysiology. This study aimed to identify age-related changes in bone tissue metabolites in C57BL/6 mice. We then correlated the differentially expressed metabolites with their functions in bone biology. In both aged males and females, hydroxyproline, glutamine, and alpha-linolenic acid levels were decreased. In aged females, Ornithine (p value = 0.001), L-Proline (p value = 0.008), Uridine (p value = 0.001), Aspartic Acid (p value = 0.004) levels were significantly decreased, and glutamate (p value = 0.002) was elevated. In aged males, N-acetyl-D-glucosamine (pvalue = 0.010), Adrenic acid (pvalue = 0.0099), Arachidonic acid (p value = 0.029) and Allantoin (p value = 0.004) levels were decreased. Metabolic pathway analysis revealed that purine and D-glutamine and D-glutamate metabolism were significantly altered in both sexes, while arginine biosynthesis in females and lipid metabolism in males were highly affected. These differences in metabolic signaling might be one of the reasons for the discrepancy in musculoskeletal disease manifestation between the two sexes. Understanding the role of these metabolites play in the aging bone will allow for new sex-specific targeted therapies against the progression of musculoskeletal diseases.

The microbiome-derived metabolite TMAO drives immune activation and boosts responses to immune checkpoint blockade in pancreatic cancer

The composition of the gut microbiome can control innate and adaptive immunity and has emerged as a key regulator of tumor growth, especially in the context of immune checkpoint blockade (ICB) therapy. However, the underlying mechanisms for how the microbiome affects tumor growth remain unclear. Pancreatic ductal adenocarcinoma (PDAC) tends to be refractory to therapy, including ICB. Using a nontargeted, liquid chromatography-tandem mass spectrometry-based metabolomic screen, we identified the gut microbe-derived metabolite trimethylamine N-oxide (TMAO), which enhanced antitumor immunity to PDAC. Delivery of TMAO intraperitoneally or via a dietary choline supplement to orthotopic PDAC-bearing mice reduced tumor growth, associated with an immunostimulatory tumor-associated macrophage (TAM) phenotype, and activated effector T cell response in the tumor microenvironment. Mechanistically, TMAO potentiated the type I interferon (IFN) pathway and conferred antitumor effects in a type I IFN-dependent manner. Delivering TMAO-primed macrophages intravenously produced similar antitumor effects. Combining TMAO with ICB (anti-PD1 and/or anti-Tim3) in a mouse model of PDAC significantly reduced tumor burden and improved survival beyond TMAO or ICB alone. Last, the levels of bacteria containing CutC (an enzyme that generates trimethylamine, the TMAO precursor) correlated with long-term survival in patients with PDAC and improved response to anti-PD1 in patients with melanoma. Together, our study identifies the gut microbial metabolite TMAO as a driver of antitumor immunity and lays the groundwork for potential therapeutic strategies targeting TMAO.

Tryptophan-derived microbial metabolites activate the aryl hydrocarbon receptor in tumor-associated macrophages to suppress anti-tumor immunity

The aryl hydrocarbon receptor (AhR) is a sensor of products of tryptophan metabolism and a potent modulator of immunity. Here, we examined the impact of AhR in tumor-associated macrophage (TAM) function in pancreatic ductal adenocarcinoma (PDAC). TAMs exhibited high AhR activity and Ahr-deficient macrophages developed an inflammatory phenotype. Deletion of Ahr in myeloid cells or pharmacologic inhibition of AhR reduced PDAC growth, improved efficacy of immune checkpoint blockade, and increased intra-tumoral frequencies of IFNγ⁺CD8⁺ T cells. Macrophage tryptophan metabolism was not required for this effect. Rather, macrophage AhR activity was dependent on Lactobacillus metabolization of dietary tryptophan to indoles. Removal of dietary tryptophan reduced TAM AhR activity and promoted intra-tumoral accumulation of TNFα⁺IFNγ⁺CD8⁺ T cells; provision of dietary indoles blocked this effect. In patients with PDAC, high AHR expression associated with rapid disease progression and mortality, as well as with an immune-suppressive TAM phenotype, suggesting conservation of this regulatory axis in human disease.

A fatal case of empyema thoracis by Nocardia farcinica in an immunocompromised patient

Empyema thoracis by Nocardia farcinica infection is uncommon. Here we report a rare and fatal infection in a 27-year-old HIV- seropositive male who presented with cough, expectoration, and breathlessness. Nocardia farcinica was isolated from sputum and pus from the pleural cavity. Confirmation of the isolate and minimum inhibitory concentrations (MIC) for various antibiotics was done at the Aerobic Actinomycetes Reference Laboratory, Centres for Disease Control and Prevention (CDC), Atlanta. Patient was treated with suitable antibiotics and antiretroviral drugs in spite of which he eventually succumbed to the disease.

Meningitis due to Rhodotorula glutinis in an HIV infected patient

Rhodotorula spp, though considered a common saprophyte, recently has been reported as causative agent of opportunistic mycoses. We present a case of meningitis in an immunocompromised human immunodeficiency virus infected patient who presented with longstanding fever. He was diagnosed as a case of chronic meningitis. Diagnosis was confirmed by cell cytology, India ink preparation, Gram staining and culture of cerebrospinal fluid (CSF) sample. CSF culture grew Rhodotorula glutinis. Therapy with amphotericin B was successful in eliminating the yeast from CSF and the patient was discharged after recovery.

Growth of textured nanocrystalline cobalt ferrite thin films by pulsed laser deposition

Cobalt ferrite thin films have been deposited on fused quartz substrates by pulsed laser deposition at various substrate temperatures, T(s) (25 degrees C, 300 degrees C, 550 degrees C and 750 degrees C). Single phase, nanocrystalline, spinel cobalt ferrite formation is confirmed by X-ray diffraction (XRD) for T(s) > or = 300 degrees C. Conventional XRD studies reveal strong (111) texturing in the as deposited films with T(s) > or = 550 degrees C. Bulk texture measurements using X-ray orientation distribution function confirmed (111) preferred orientation in the films with T(s) > or = 550 degrees C. Grain size (13-16 nm for T(s) > or = 300 degrees C) estimation using grazing incidence X-ray line broadening analysis shows insignificant grain growth with increasing T(s), which is in good agreement with grain size data obtained from transmission electron microscopy.

Review of clinical and laboratory features of human brucellosis

Infection with Brucella spp. continues to pose a human health risk globally despite strides in eradicating the disease from domestic animals. Brucellosis has been an emerging disease since the discovery of Brucella melitensis by Sir David Bruce in 1887. Although many countries have eradicated B. abortus from cattle, in some areas B. melitensis and B. suis have emerged as causes of this infection in cattle, leading to human infections. Currently B. melitensis remains the principal cause of human brucellosis worldwide including India. The recent isolation of distinct strains of Brucella from marine mammals as well as humans is an indicator of an emerging zoonotic disease. Brucellosis in endemic and non-endemic regions remains a diagnostic puzzle due to misleading non-specific manifestations and increasing unusual presentations. Fewer than 10% of human cases of brucellosis may be clinically recognized and treated or reported. Routine serological surveillance is not practiced even in Brucella - endemic countries and we suggest that this should be a part of laboratory testing coupled with a high index of clinical suspicion to improve the level of case detection. The screening of family members of index cases of acute brucellosis in an endemic area should be undertaken to pick up additional unrecognised cases. Rapid and reliable, sensitive and specific, easy to perform and automated detection systems for Brucella spp. are urgently needed to allow early diagnosis and adequate antibiotic therapy in time to decrease morbidity / mortality. The history of travel to endemic countries along with exposure to animals and exotic foods are usually critical to making the clinical diagnosis. Laboratory testing is indispensable for diagnosis. Therefore alertness of clinician and close collaboration with microbiologist are essential even in endemic areas to correctly diagnose and treat this protean human infection. Existing treatment options, largely based on experience gained > 30 years ago, are adequate but not optimal. In our experience, an initial combination therapy with a three drug-regimen followed by a two-drug regimen for at least six weeks and a combination of two drugs with a minimum of six weeks seems warranted to improve outcome in children and adult patients respectively with laboratory monitoring. A safe and effective vaccine in humans is not yet available. Prevention is dependent upon the control of the disease in animal hosts, effective heat treatment of dairy produce and hygienic precautions to prevent occupational exposure. This review compiles the experiences and diagnostic and treatment paradigms currently employed in fighting this disease.

Pre- and posttreatment MR imaging findings in lead encephalopathy

A 41-year-old man suspected of having lead poisoning was evaluated with MR imaging before and after British antilewisite therapy. The MR imaging findings showed bilateral symmetric involvement of the occipital lobe, affecting predominantly the gray-white matter junction and the subcortical white matter. A right cerebellar lesion was noted, with focal hyperintensities involving the gray-white matter. Similar lesions were seen in the temporal, parietal, and frontal regions. These lesions resolved after chelation therapy.