Using network analysis to examine links between individual depressive symptoms, inflammatory markers, and covariates.

BACKGROUND: Studies investigating the link between depressive symptoms and inflammation have yielded inconsistent results, which may be due to two factors. First, studies differed regarding the specific inflammatory markers studied and covariates accounted for. Second, specific depressive symptoms may be differentially related to inflammation. We address both challenges using network psychometrics. METHODS: We estimated seven regularized Mixed Graphical Models in the Netherlands Study of Depression and Anxiety (NESDA) data (N = 2321) to explore shared variances among (1) depression severity, modeled via depression sum-score, nine DSM-5 symptoms, or 28 individual depressive symptoms; (2) inflammatory markers C-reactive protein (CRP), interleukin 6 (IL-6), and tumor necrosis factor α (TNF-α); (3) before and after adjusting for sex, age, body mass index (BMI), exercise, smoking, alcohol, and chronic diseases. RESULTS: The depression sum-score was related to both IL-6 and CRP before, and only to IL-6 after covariate adjustment. When modeling the DSM-5 symptoms and CRP in a conceptual replication of Jokela et al., CRP was associated with 'sleep problems', 'energy level', and 'weight/appetite changes'; only the first two links survived covariate adjustment. In a conservative model with all 38 variables, symptoms and markers were unrelated. Following recent psychometric work, we re-estimated the full model without regularization: the depressive symptoms 'insomnia', 'hypersomnia', and 'aches and pain' showed unique positive relations to all inflammatory markers. CONCLUSIONS: We found evidence for differential relations between markers, depressive symptoms, and covariates. Associations between symptoms and markers were attenuated after covariate adjustment; BMI and sex consistently showed strong relations with inflammatory markers.

Biosynthetic gene cluster of simocyclinone, a natural multihybrid antibiotic.

The entire simocyclinone biosynthetic cluster (sim gene cluster) from the producer Streptomyces antibioticus Tü6040 was identified on six overlapping cosmids (1N1, 5J10, 2L16, 2P6, 4G22, and 1K3). In total, 80.7 kb of DNA from these cosmids was sequenced, and the analysis revealed 49 complete open reading frames (ORFs). These ORFs include genes responsible for the formation and attachment of four different moieties originating from at least three different pools of primary metabolites. Also in the sim gene cluster, four ORFs were detected that resemble putative regulatory and export functions. Based on the putative function of the gene products, a model for simocyclinone D8 biosynthesis was proposed. Biosynthetic mutants were generated by insertional gene inactivation experiments, and culture extracts of these mutants were analyzed by high-performance liquid chromatography. Production of simocyclinone D8 was clearly detectable in the wild-type strain but was not detectable in the mutant strains. This indicated that indeed the sim gene cluster had been cloned.

An ATP-binding cassette transporter and two rRNA methyltransferases are involved in resistance to avilamycin in the producer organism Streptomyces viridochromogenes Tü57.

Three different resistance factors from the avilamycin biosynthetic gene cluster of Streptomyces viridochromogenes Tü57, which confer avilamycin resistance when expressed in Streptomyces lividans TK66, were isolated. Analysis of the deduced amino acid sequences showed that AviABC1 is similar to a large family of ATP-binding transporter proteins and that AviABC2 resembles hydrophobic transmembrane proteins known to act jointly with the ATP-binding proteins. The deduced amino acid sequence of aviRb showed similarity to those of other rRNA methyltransferases, and AviRa did not resemble any protein in the databases. Independent expression in S. lividans TK66 of aviABC1 plus aviABC2, aviRa, or aviRb conferred different levels of resistance to avilamycin: 5, 10, or 250 microg/ml, respectively. When either aviRa plus aviRb or aviRa plus aviRb plus aviABC1 plus aviABC2 was coexpressed in S. lividans TK66, avilamycin resistance levels reached more than 250 microg/ml. Avilamycin A inhibited poly(U)-directed polyphenylalanine synthesis in an in vitro system using ribosomes of S. lividans TK66(pUWL201) (GWO), S. lividans TK66(pUWL201-Ra) (GWRa), or S. lividans TK66(pUWL201-Rb) (GWRb), whereas ribosomes of S. lividans TK66 containing pUWL201-Ra+Rb (GWRaRb) were highly resistant. aviRa and aviRb were expressed in Escherichia coli, and both enzymes were purified as fusion proteins to near homogeneity. Both enzymes showed rRNA methyltransferase activity using a mixture of 16S and 23S rRNAs from E. coli as the substrate. Coincubation experiments revealed that the enzymes methylate different positions of rRNA.

Elucidation of the function of two glycosyltransferase genes (lanGT1 and lanGT4) involved in landomycin biosynthesis and generation of new oligosaccharide antibiotics.

BACKGROUND: The genetic engineering of antibiotic-producing Streptomyces strains is an approach that became a successful methodology in developing new natural polyketide derivatives. Glycosyltransferases are important biosynthetic enzymes that link sugar moieties to aglycones, which often derive from polyketides. Biological activity is frequently generated along with this process. Here we report the use of glycosyltransferase genes isolated from the landomycin biosynthetic gene cluster to create hybrid landomycin/urdamycin oligosaccharide antibiotics. RESULTS: Production of several novel urdamycin derivatives by a mutant of Streptomyces fradiae Tü2717 has been achieved in a combinatorial biosynthetic approach using glycosyltransferase genes from the landomycin producer Streptomyces cyanogenus S136. For the generation of gene cassettes useful for combinatorial biosynthesis experiments new vectors named pMUNI, pMUNII and pMUNIII were constructed. These vectors facilitate the construction of gene combinations taking advantage of the compatible MunI and EcoRI restriction sites. CONCLUSIONS: The high-yielding production of novel oligosaccharide antibiotics using glycosyltransferase gene cassettes generated in a very convenient way proves that glycosyltransferases can be flexible towards the alcohol substrate. In addition, our results indicate that LanGT1 from S. cyanogenus S136 is a D-olivosyltransferase, whereas LanGT4 is a L-rhodinosyltransferase.

Function of glycosyltransferase genes involved in urdamycin A biosynthesis.

BACKGROUND: Urdamycin A, the principle product of Streptomyces fradiae Tü2717, is an angucycline-type antibiotic. The polyketide-derived aglycone moiety is glycosylated at two positions, but only limited information is available about glycosyltransferases involved in urdamycin biosynthesis. RESULTS: To determine the function of three glycosyltransferase genes in the urdamycin biosynthetic gene cluster, we have carried out gene inactivation and expression experiments. Inactivation of urdGT1a resulted in the predominant accumulation of urdamycin B. A mutant lacking urdGT1b and urdGT1c mainly produced compound 100-2. When urdGT1c was expressed in the urdGT1b/urdGT1c double mutant, urdamycin G and urdamycin A were detected. The mutant lacking all three genes mainly accumulated aquayamycin and urdamycinone B. Expression of urdGT1c in the triple mutant led to the formation of compound 100-1, whereas expression of urdGT1a resulted in the formation of compound 100-2. Co-expression of urdGT1b and urdGT1c resulted in the production of 12b-derhodinosyl-urdamycin A, and co-expression of urdGT1a, urdGT1b and urdGT1c resulted in the formation of urdamycin A. CONCLUSIONS: Analysis of glycosyltransferase genes of the urdamycin biosynthetic gene cluster led to an unambiguous assignment of each glycosyltransferase to a certain biosynthetic saccharide attachment step.

Cloning of an avilamycin biosynthetic gene cluster from Streptomyces viridochromogenes Tü57.

A 65-kb region of DNA from Streptomyces viridochromogenes Tü57, containing genes encoding proteins involved in the biosynthesis of avilamycins, was isolated. The DNA sequence of a 6.4-kb fragment from this region revealed four open reading frames (ORF1 to ORF4), three of which are fully contained within the sequenced fragment. The deduced amino acid sequence of AviM, encoded by ORF2, shows 37% identity to a 6-methylsalicylic acid synthase from Penicillium patulum. Cultures of S. lividans TK24 and S. coelicolor CH999 containing plasmids with ORF2 on a 5.5-kb PstI fragment were able to produce orsellinic acid, an unreduced version of 6-methylsalicylic acid. The amino acid sequence encoded by ORF3 (AviD) is 62% identical to that of StrD, a dTDP-glucose synthase from S. griseus. The deduced amino acid sequence of AviE, encoded by ORF4, shows 55% identity to a dTDP-glucose dehydratase (StrE) from S. griseus. Gene insertional inactivation experiments of aviE abolished avilamycin production, indicating the involvement of aviE in the biosynthesis of avilamycins.

Examination of non-involved skin, previously involved skin, and peripheral blood for herpes simplex virus DNA in patients with recurrent herpes-associated erythema multiforme.

The association between infection with HSV and the subsequent development of erythema multiforme is well established, although the role that the virus plays in the pathogenesis of this disorder is not known. HSV DNA has been detected in cutaneous lesions of herpes-associated erythema multiforme (HAEM), and it has been suggested that the tissue damage seen in these lesions is virus-specific. In the current, prospective study, we examined biopsies of lesional, non-involved, and previously involved but healed skin, in addition to specimens of peripheral blood, from patients with HAEM, for HSV DNA by using the polymerase chain reaction. HSV DNA was detected in lesional skin of 10 of 11 patients compared to 2 of 11 non-involved skin biopsies obtained at the same time. HSV was present in 4 of 6 blood specimens obtained during the acute episode. Five patients returned 3 months after the acute episode resolved for biopsies of previously involved skin. HSV was detected in 4 of these 5 biopsies. Thus, the presence of HSV DNA in the skin of patients with HAEM appears to be predominantly in areas of clinical involvement; the virus remains in those cutaneous sites for up to 3 months without evidence of clinical disease; and HSV DNA may be detected in the peripheral blood cells during acute HAEM. Based on these findings, we suggest that the virus plays a role in lesion development, that the skin may function as a site of viral persistence, and that hematogenous spread of viral DNA may be an important factor in the development of HAEM.

Human herpesvirus 6 is present in lesions of Langerhans cell histiocytosis.

Langerhans cell histiocytosis (LCH) is a disease characterized by Langerhans cell infiltration of skin and bone, with its most severe form manifested by multifocal infiltration of many organs. The etiology is unknown, although viral infection has been proposed as a potential pathogenic factor. Human herpesvirus 6 (HHV-6), a recently described member of the human herpesvirus family, has been associated with atypical or malignant lymphocytic processes, and immune disorders. Based on these observations, we suspected that HHV-6 may play a role in the pathogenesis of LCH. Lesional tissue of 30 patients with LCH was retrospectively examined for the presence of HHV-6 by using the polymerase chain reaction. Tissue specimens from 63 patients with other benign and malignant histiocytic and lymphocytic diseases served as controls. In addition, all specimens were examined with control primers specific for herpes simplex virus (HSV). HHV-6 DNA was detected in lesions of 14 of 30 patients with LCH (47%). On clinical subgroup analysis, HHV-6 DNA was found in 10 of 16 patients with extraosseous disease (63%) and in four of 14 patients with disease limited to bone (29%). In each case, the prevalence of HHV-6 in LCH lesions was statistically significant, when compared to the control population. HSV DNA was not found in any of the LCH or control specimens. Although the presence of a virus alone does not establish a causal role in the disease, it supports the possibility of an etiologic relationship. From this study, we emphasize the need for further investigation of the potential HHV-6-mediated pathogenesis of LCH.

Examination of cutaneous T-cell lymphoma for human herpesviruses by using the polymerase chain reaction.

The etiology of cutaneous T-cell lymphoma remains unknown, although an association with viral infection, in particular certain retroviruses and human herpesviruses, has been suggested. The purpose of this study was to examine skin biopsies of cutaneous T-cell lymphoma for the presence of Epstein-Barr virus, herpes simplex virus type 1 and type 2, and human herpesvirus-6 by using the polymerase chain reaction. Lesional skin biopsies from 30 patients with cutaneous T-cell lymphoma were studied. Control specimens included biopsies from 9 patients with lymphomatoid papulosis and 10 patients with pityriasis lichenoides et varioliformis acuta. DNA extracted from each specimen, as well as from a known positive control for each virus, was examined by using the polymerase chain reaction with viral-specific primers. Each DNA specimen was also amplified with control primers for human beta globin. The specificity of the amplified products was confirmed by Southern analysis. Neither Epstein-Barr virus nor herpes simplex virus was detected in any of the patient specimens examined. Human herpesvirus-6 was detected in one specimen of cutaneous T-cell lymphoma and one specimen of lymphomatoid papulosis. These results do not support a role for any of these herpesviruses in the pathogenesis of cutaneous T-cell lymphoma.

The herpes-specific immune response of individuals with herpes-associated erythema multiforme compared with that of individuals with recurrent herpes labialis.

Infection with herpes simplex virus (HSV) is the most common precipitating factor in the development of erythema multiforme (EM). It is not known why only a few of the many individuals who experience recurrent HSV infection also develop herpes-associated EM (HAEM), although a difference in the HSV-specific immune response has been postulated. The purpose of this study was to compare the HSV-specific immune response of individuals with HSV infection alone with that of individuals with HAEM. There were 21 patients in each of the two groups. Four parameters of the HSV-specific immune response were examined: (1) anti-HSV IgG titers were measured by ELISA; (2) antibody neutralization was assessed using a plaque assay; and (3) antibody-dependent complement-mediated cytotoxicity, and (4) antibody-dependent cellular cytotoxicity were investigated using a previously described in vitro HSV-specific cytotoxicity assay. No statistically significant differences were detected between the two patient groups. Thus, a difference in these HSV-specific immune mechanisms does not explain the development of HAEM in some individuals with recurrent HSV infection.

Detection of herpes simplex virus DNA in the peripheral blood during acute recurrent herpes labialis.

BACKGROUND: Although herpes simplex virus (HSV) has been detected in the peripheral blood of immunocompromised patients and in neonates with disseminated disease, the extent to which this virus may be present in the blood during a localized infection in otherwise healthy adults is unknown. OBJECTIVE: The purpose of this study was to determine whether HSV may be detected in the peripheral blood during acute recurrent herpes labialis. METHODS: Peripheral blood mononuclear cells (PBMCs) were obtained from otherwise healthy adults with recurrent herpes labialis, both during an acute episode and several weeks after the lesions had healed. The PBMCs were examined for the presence of HSV with the polymerase chain reaction (PCR) and viral culture. RESULTS: By PCR, HSV DNA was detected in 7 of 34 specimens from an acute episode but in none of 24 specimens in the convalescent stage (p less than 0.004). PBMCs from seven donors, who were seronegative for HSV, were also negative for HSV by PCR. Viral cultures of 22 PBMC specimens were negative (including four specimens that were positive by PCR). CONCLUSION: The presence of HSV DNA in the blood is a transient phenomenon limited to the period of active infection in a minority of patients with herpes labialis, although it may be important in the development of disseminated disease as well as in the pathogenesis of herpes-associated cutaneous processes such as erythema multiforme.

Herpes simplex virus in childhood erythema multiforme.

Although an association between herpes simplex virus (HSV) infection and erythema multiforme (EM) minor has been documented in adults, this has not been reported in the pediatric population. This study assessed the potential role of HSV infection in the pathogenesis of EM minor in children. Erythema multiforme skin lesions from 20 children, aged 1 to 16 years, were examined for the presence of HSV by using the polymerase chain reaction. The children included all fit strict clinical criteria for EM minor. Ten had a clinical history of an antecedent herpes infection ("herpes-associated EM"), and 10 did not ("idiopathic EM"). Herpes simplex virus DNA was detected in skin lesions of 8 of 10 children with herpes-associated EM and in 8 of 10 with idiopathic EM. Control skin biopsies from children with other bullous inflammatory diseases were negative. In addition, no HSV could be detected in a biopsy of normal uninvolved skin of a child in whom HSV was present in lesional skin. In situ hybridization on selected biopsies by means of an HSV-specific riboprobe confirmed the presence of HSV and localized it to the epidermis. It is concluded that HSV is a significant precipitating factor for EM minor in children, as it is in adults, and that clinicians should maintain a high index of suspicion of HSV even in the absence of a known history of herpes infection.