Deactivation of endothelium and reduction in angiogenesis in psoriatic skin and synovium by low dose infliximab therapy in combination with stable methotrexate therapy: a prospective single-centre study

Psoriasis and psoriatic arthritis are inflammatory diseases that respond well to anti-tumour necrosis factor-α therapy. To evaluate the effects of anti-tumour necrosis factor-α treatment on expression of adhesion molecules and angiogenesis in psoriatic lesional skin and synovial tissue, we performed a prospective single-centre study with infliximab therapy combined with stable methotrexate therapy. Eleven patients with both active psoriasis and psoriatic arthritis received infusions of infliximab (3 mg/kg) at baseline, and at weeks 2, 6, 14 and 22 in an open-label study. In addition, patients continued to receive stable methotrexate therapy in dosages ranging from 5 to 20 mg/week. Clinical assessments, including Psoriasis Area and Severity Index (PASI) and Disease Activity Score (DAS), were performed at baseline and every 2 weeks afterward. In addition, skin biopsies from a target psoriatic plaque and synovial tissue biopsies from a target joint were taken before treatment and at week 4. Immunohistochemical analysis was performed to detect the number of blood vessels, the expression of adhesion molecules and the presence of vascular growth factors. Stained sections were evaluated by digital image analysis. At week 16, the mean PASI was reduced from 12.3 ± 2.4 at baseline to 1.8 ± 0.4 (P ≤ 0.02). The mean DAS was reduced from 6.0 ± 0.5 to 3.6 ± 0.6 (P ≤ 0.02). We found some fluctuations in DAS response as compared with the change in PASI, with the latter exhibiting a steady decrease over time. After 4 weeks the cell infiltrate was reduced in both skin and synovium. There was a significant reduction in the number of blood vessels in dermis and synovium at week 4. A significant reduction in the expression of α_vβ₃ integrin, a marker of neovascularization, was also found in both skin and synovium at week 4. In addition, a significant reduction in the expression of adhesion molecules was observed in both skin and synovium at week 4. We also observed a trend toward reduced expression of vascular endothelial growth factor in both skin and synovium. In conclusion, low-dose infliximab treatment leads to decreased neoangiogenesis and deactivation of the endothelium, resulting in decreased cell infiltration and clinical improvement in psoriasis and psoriatic arthritis.     

Interferon-alpha promotes survival of human primary B-lymphocytes via phosphatidylinositol 3-kinase

Signaling pathways for the antiviral and antiproliferative biological effects of type I interferons (IFN) are well established. In this report we demonstrate a novel signaling pathway for IFN-alpha, as it induced rapid phosphorylation of both PKB/Akt and its substrate forkhead. The PI3-kinase inhibitor LY294002 abolished these phosphorylations. PI3-kinase has been implicated in cell survival mediating its effect through the second messenger PIP3 and the subsequent activation of PKB/Akt. We could show that IFN-alpha inhibited spontaneous apoptosis of primary B-lymphocytes, in the absence of a mitogenic stimulus. This effect was inhibited by LY294002. Thus, our data suggests that IFN-alpha promotes survival of peripheral B-lymphocytes via the PI3-kinase-PKB/Akt pathway. In addition, IFN-alpha stimulation of anti-IgM activated cells resulted in downregulated expression of the cell cycle inhibitor p27/Kip1.     

Chromosomally encoded arsenical resistance of the moderately thermophilic acidophile Acidithiobacillus caldus

Arsenical resistance is important to bioleaching microorganisms because these organisms release arsenic from minerals such as arsenopyrite during bioleaching. The acidophile Acidithiobacillus caldus KU was found to be resistant to the arsenical ions arsenate, arsenite, and antimony via an inducible, chromosomally encoded resistance mechanism. Because no apparent alteration of the toxic ions was observed, Acidithiobacillus (At.) caldus was tested to determine if it was resistant as a result of decreased accumulation of toxic ions. Reduced accumulation of arsenate and arsenite by induced At. caldus cells supported this hypothesis. It was also found that, with the addition of an energy source, induced At. caldus could transport arsenate and arsenite out of the cell against a concentration gradient. The lack of efflux in the absence of an added energy source and in the presence of inhibitors suggested that efflux was energy dependent. Induced At. caldus also expressed arsenate reductase activity, indicating that At. caldus has an arsenical resistance mechanism that is analogous to previously described systems from other Bacteria. Southern hybridization analysis showed that At. caldus and other gram-negative acidophiles carry an Escherichia coli arsB homologue on the chromosome.     

Multiple Serotypes of the Moderate Thermophile Thiobacillus caldus, a Limitation of Immunological Assays for Biomining Microorganisms

Phylogenetic and phenotypic analysis indicates that a moderately thermophilic isolate, C-SH12, from Australia belongs to the species Thiobacillus caldus. Antiserum generated against whole cells of T. caldus KU recognized protein antigens common to cell lysates of the three T. caldus strains KU, BC13, and C-SH12 but did not recognize whole cells of isolate C-SH12. Differences in the lipopolysaccharide (LPS) of strain C-SH12 and those of the other two T. caldus strains were found, and the anti-KU antiserum did not recognize the LPS from strain C-SH12. These data indicate that this T. caldus isolate belongs to a serotype different from that of strains KU and BC13.     

Flagellar sensilla of the eusocial gall-inducing thrips Kladothrips intermedius and its kleptoparasite, Koptothrips dyskritus (Thysanoptera: Phlaeothripinae)

Insect antennal flagella host a multitude of sensory organs fulfilling different functions. Chemoreception, for example, is essential for insects in many contexts. Both olfaction and contact chemoreception are involved in host-plant selection, as well as in the integrity of insect societies, especially for nestmate recognition. Kladothrips intermedius is a eusocial gall-inducing thrips with two castes: dispersers and soldiers. Koptothrips dyskritus is a specialist in invading Kl. intermedius galls, killing the occupants, and thereby gaining the food and shelter offered by galls. In this study, we compared the morphology and ultrastructure of the flagellar sensilla of Kl. intermedius and Ko. dyskritus via scanning and transmission electron microscopy in order to facilitate future investigations of their sensory ecology, with an emphasis on chemical ecology. The two species show a very similar sensillar array. There are a few mechanosensory trichoid and a second type of mechanosensory sensilla, thermo-hygroreceptive sensilla, olfactory single-walled basiconic and double-walled coeloconic sensilla as well as contact chemoreceptive chaetic sensilla. The latter are sexually dimorphic in Kl. intermedius. Dispersers and soldiers of Kl. intermedius do not present noteworthy morphological differences, but the ultrastructural investigations revealed that soldiers have fewer ORNs, possibly an adaptation to their gall-cloistered lifestyle.     

The neuroblastoma ALK(I1250T) mutation is a kinase-dead RTK in vitro and in vivo

Activating mutations in the kinase domain of anaplastic lymphoma kinase (ALK) have recently been shown to be an important determinant in the genetics of the childhood tumor neuroblastoma. Here we discuss an in-depth analysis of one of the reported gain-of-function ALK mutations-ALK(I1250T)-identified in the germ line DNA of one patient. Our analyses were performed in cell culture-based systems and subsequently confirmed in a Drosophila model. The results presented here indicate that the germ line ALK(I1250T) mutation is most probably not a determinant for tumor initiation or progression and, in contrast, seems to generate a kinase-dead mutation in the ALK receptor tyrosine kinase (RTK). Consistent with this, stimulation with agonist ALK antibodies fails to lead to stimulation of ALK(I1250T) and we were unable to detect tyrosine phosphorylation under any circumstances. In agreement, ALK(I1250T) is unable to activate downstream signaling pathways or to mediate neurite outgrowth, in contrast to the activated wild-type ALK receptor or the activating ALK(F1174S) mutant. Identical results were obtained when the ALK(I1250T) mutant was expressed in a Drosophila model, confirming the lack of activity of this mutant ALK RTK. We suggest that the ALK(I1250T) mutation leads to a kinase-dead ALK RTK, in stark contrast to assumed gain-of-function status, with significant implications for patients reported to carry this particular ALK mutation.     

N and P colimitation of N2-fixing and N-supplied fynbos legumes from the Cape Floristic Region

Background and aims

Legume species in the fynbos vegetation of the Cape Floristic Region, that fix N₂ in soils with low P, may have evolved for enhanced acquisition and efficient use of P. It was hypothesized that N₂-fixing and combined-N supplied (N-supplied) A. linearis, P. calyptrata and C. genistoides are adapted to low P and would be relatively unresponsive to increased P of 100 μM.

Methods

18 legume species were evaluated for their nodulation response to low P availability. The N X P interaction was then examined in A. linearis, P. calyptrata and C. genistoides reliant on either N₂-fixation or 300 μM N (NH₄NO₃), and receiving 0.1, 1.0, 10 and 100 μM P (NaH₂PO₄).

Results

In the species selection experiment, A. linearis, P. calyptrata and C. genistoides, with the greatest nodule fresh weight (FW) and nodule FW to root FW ratio, were the most prolific nodulating species. In the N X P experiment, with low P supply, the biomass of N₂-fixing P. calyptrata and C. genistoides was consistently greater than that of N-supplied plants. In contrast, with high P supply of 100 μM P, all N-supplied plants accumulated more biomass than the corresponding N₂-fixing plants. High P-use efficiency, poor down-regulation of P uptake and P storage was evident in A. linearis and P. calyptrata.

Conclusion

The growth response to P and the significant N X P interactions indicate that N₂-fixing and N-supplied plants were not adapted to low P, but rather colimited by both N and P.     

Second messengers and divergent HD-GYP phosphodiesterases regulate 3′,3′-cGAMP signaling

3′,3′-cyclic GMP-AMP (cGAMP) is the third cyclic dinucleotide (CDN) to be discovered in bacteria. No activators of cGAMP signaling have yet been identified, and the signaling pathways for cGAMP have been inferred to display a narrow distribution based upon the characterized synthases, DncV and Hypr GGDEFs. Here, we report that the ubiquitous second messenger cyclic AMP (cAMP) is an activator of the Hypr GGDEF enzyme GacB from Myxococcus xanthus. Furthermore, we show that GacB is inhibited directly by cyclic di-GMP, which provides evidence for cross-regulation between different CDN pathways. Finally, we reveal that the HD-GYP enzyme PmxA is a cGAMP-specific phosphodiesterase (GAP) that promotes resistance to osmotic stress in M. xanthus. A signature amino acid change in PmxA was found to reprogram substrate specificity and was applied to predict the presence of non-canonical HD-GYP phosphodiesterases in many bacterial species, including phyla previously not known to utilize cGAMP signaling.     

The Ultrastructural Characteristics of the Pheromone Gland Cells of Dendrolimus pini (Insecta: Lepidoptera)

Abstract In the females of Dendrolimus pini the pheromone-producing epithelium is present ventrally between the 8th and 9th abdominal segments. The epithelium is about 40 μm thick. The cells possess extensive microvillar borders, both apically towards the cuticle and laterally, towards the adjoining cells. In the spaces between the cells in the upper half of the epithelium there are loosely arranged cuticular lamellae adjacent to the microvillous borders. The epithelial cells have large, basally situated nuclei, whereas the apical parts have extensive arrangements of tightly packed and orderly arranged smooth endoplasmic reticulum. Clear vesicles and microbod–ies are present in the cytoplasm. The gland has a structural potential for high pheromone-producing capacity (the well-developed endoplasmic reticulum) as well as an effective emission apparatus (the microvillous borders/cuticular lamellae). These two elements could facilitate a pulsed pheromone emission that is effective in arousing the sensory system of males.