Tissue Distribution of Doxycycline in Animal Models of Tuberculosis.

Doxycycline, an FDA-approved tetracycline, is used in tuberculosis in vivo models for the temporal control of mycobacterial gene expression. In these models, animals are infected with recombinant Mycobacterium tuberculosis carrying genes of interest under transcriptional control of the doxycycline-responsive TetR-tetO unit. To minimize fluctuations of plasma levels, doxycycline is usually administered in the diet. However, tissue penetration studies to identify the minimum doxycycline content in food achieving complete repression of TetR-controlled genes in tuberculosis (TB)-infected organs and lesions have not been conducted. Here, we first determined the tetracycline concentrations required to achieve silencing of M. tuberculosis target genes in vitro Next, we measured doxycycline concentrations in plasma, major organs, and lung lesions in TB-infected mice and rabbits and compared these values to silencing concentrations measured in vitro We found that 2,000 ppm doxycycline supplemented in mouse and rabbit feed is sufficient to reach target concentrations in TB lesions. In rabbit chow, the calcium content had to be reduced 5-fold to minimize chelation of doxycycline and deliver adequate oral bioavailability. Clearance kinetics from major organs and lung lesions revealed that doxycycline levels fall below concentrations that repress tet promoters within 7 to 14 days after doxycycline is removed from the diet. In summary, we have shown that 2,000 ppm doxycycline supplemented in standard mouse diet and in low-calcium rabbit diet delivers concentrations adequate to achieve full repression of tet promoters in infected tissues of mice and rabbits.

Direct profiling of the phospholipid composition of adult Caenorhabditis elegans using whole-body imaging mass spectrometry.

A protocol for the direct analysis of the phospholipid composition in the whole body of adult soil nematode, Caenorhabditis elegans (C. elegans), was developed, which combined freeze-cracking of the exoskeletal cuticle and matrix-assisted laser desorption/ionization-imaging mass spectrometry (MALDI-IMS). Biomolecules in the m/z range from 700 to 900 were more effectively detected in the freeze-cracked than from simple frozen adult nematode bodies. Different distribution of biomolecules was observed in a nematode body when the matrix was applied with a sublimation deposition method. The whole-body IMS technique was applied on genetically deficient mutant C. elegans to combine whole-body lipidomics and genetics, by comparing the fatty acid compositions, especially of the phosphatidylcholine (PC) species, between the wild-type and fat-1 mutants, which lack the gene encoding an n-3 fatty acid desaturase. A significant reduction of PC(20:5/20:5) and PC(20:4/20:5) and a marked increase of PC(20:4/20:4), PC(20:3/20:4), and PC(20:3/20:3) were detected in the fat-1 mutants in positive ion mode. In addition, phospholipid compositions other than PCs were analyzed in negative ion mode. A loss of a possible phosphatidylinositol (PI) with 18:0/20:5 and a compensative accumulation of putative PI(18:0/20:4) were detected in the fat-1 mutants. In conclusion, the whole-body MALDI-IMS technique is useful for the profiling of multiple biomolecules in C. elegans in both intra- and inter-individual levels.

Decreased level of phosphatidylcholine (16:0/20:4) in multiple myeloma cells compared to plasma cells: a single-cell MALDI-IMS approach.

Lipid metabolic changes under diseased conditions, particularly in solid tumors, are attracting increased attention. However, in non-solid tumors, including most hematopoietic tumors, lipid analyses are scarce. Multiple myeloma (MM) is a plasma cell disorder arising from bone marrow, and the lipid status of MM cells has not been reported yet. In this study, we analyzed flow cytometry-sorted single MM cells and normal plasma cells (NPCs) using matrix-assisted laser desorption/ionization-imaging mass spectrometry (MALDI-IMS), a two-dimensional label-free mass spectrometry technique for biomolecular analysis, to obtain specific lipid information. We isolated 1.31-5.77% of MM cells and 0.03-0.24% of NPCs using fluorescence-activated cell sorting (FACS). Analysis of purified cells using MALDI-IMS at the single-cell level revealed that the peak intensity and ion signals of phosphatidylcholine [PC (16:0/20:4) + H](+) at m/z 782.5 were significantly decreased in MM cells compared to NPCs. By examining particular cell populations rather than cell mixtures, our method can become a suitable tool for the analysis of rare cell populations at the single-cell level and advance the understanding of MM progression.

Alterations of human skin microbiome and expansion of antimicrobial resistance after systemic antibiotics.

Although systemic antibiotics are critical in controlling infections and reducing morbidity and mortality, overuse of antibiotics is presumed to contribute to negative repercussions such as selection of antimicrobial-resistant organisms and collateral damage to commensal microbes. In a prospective, randomized study of four clinically relevant antibiotic regimens [doxycycline (20 mg or 100 mg), cephalexin, or trimethoprim/sulfamethoxazole], we investigated microbial alterations on skin after administration of systemic antibiotics to healthy human volunteers. Samples from different skin and oral sites, as well as stool, were collected before, during, and up to 1 year after antibiotic use, and shotgun metagenomic sequencing was performed. Taxonomic analysis showed that subjects receiving doxycycline 100 mg and trimethoprim/sulfamethoxazole (TMP/SMX) exhibited greater changes to their skin microbial communities, as compared to those receiving other regimens or untreated controls. Oral and stool microbiota also demonstrated fluctuations after antibiotics. Bacterial culturing in combination with whole-genome sequencing revealed specific emergence, expansion, and persistence of antibiotic-resistant staphylococci harboring tetK or tetL and dfrC or dfrG genes in all subjects who received doxycycline 100 mg or TMP/SMX, respectively. Last, analysis of metagenomic data revealed an increase of genes involved in gene mobilization, indicating stress responses of microbes to antibiotics. Collectively, these findings demonstrate direct, long-lasting effects of antibiotics on skin microbial communities, highlighting the skin microbiome as a site for the development and persistence of antibiotic resistance and the risks of overprescribing.

Palmitic acid, verified by lipid profiling using secondary ion mass spectrometry, demonstrates anti-multiple myeloma activity.

Recent studies indicate that lipid metabolic changes affect the survival of multiple myeloma (MM) cells. Time-of-flight secondary ion mass spectrometry (TOF-SIMS), an imaging mass spectrometry technique, is used to visualize the subcellular distribution of biomolecules including lipids. We therefore applied this method to human clinical specimens to analyze the membrane fatty acid composition and determine candidate molecules for MM therapies. We isolated MM cells and normal plasma cells (PCs) from bone marrow aspirates of MM patients and healthy volunteers, respectively, and these separated cells were analyzed by TOF-SIMS. Multiple ions including fatty acids were detected and their ion counts were estimated. In MM cells, the mean intensity of palmitic acid was significantly lower than the mean intensity in PCs. In a cell death assay, palmitic acid reduced U266 cell viability dose-dependently at doses between 50 and 1000 µM. The percentage of apoptotic cells increased from 24h after palmitic acid administration. In contrast, palmitic acid had no effect on the viability of normal peripheral blood mononuclear cells (PBMCs). The results of this study indicated that palmitic acid is a potential candidate for novel therapeutic agents that specifically attack MM cells.

Intravascular large B-cell lymphoma manifesting as cholecystitis: report of an Asian variant showing gain of chromosome 18 with concurrent deletion of chromosome 6q.

Intravascular large B-cell lymphoma (IVLBCL), which involves the lumen of small vessels, is a rare variant of extranodal diffuse large B-cell lymphomas. Herein, we present a case of IVLBCL manifesting as cholecystitis in a 77-year-old Japanese man. He presented with fever, fatigue, and weight loss. Physical examination revealed tenderness of the right upper quadrant. The white blood cell count and C-reactive protein levels were elevated. Computed tomography revealed gallbladder thickening and pericholecystic fluid collection; these observations were consistent with the diagnosis of cholecystitis. Serum soluble interleukin-2 receptor levels were highly elevated, and gallium scintigraphy revealed an abnormal accumulation in the spleen, implying lymphoma. Consequently, G-banding analysis of the patient's bone marrow aspirates revealed the presence of different abnormal clones, including those with gain of chromosome 18 and deletion of chromosome 6q. As cholecystectomy was necessary, a concurrent splenectomy was performed to diagnose the disease definitively. Histopathologically, atypical large lymphoid cells were observed to be localized in the vasculature in both the spleen and gallbladder; the atypical cells expressed high levels of CD20, CD5, and CD10, immunohistochemically. These findings were consistent with IVLBCL. The patient underwent post-operative treatment with rituximab, cyclophosphamide, adriamycin, vincristine, and prednisolone. However, a pancreatic fistula developed during chemotherapy, causing left pleural effusion and peritoneal effusion; the patient developed sepsis from multidrug-resistant microorganisms, and subsequently died of multi-organ failure 6 months after the diagnosis. No obvious recurrence of the tumor was found during autopsy. We discuss the characteristic karyotype and immunohistochemical status observed in this case.