POS0100 ACTIVATION OF THE CELLULAR INTEGRATED STRESS RESPONSE IN LABIAL SALIVARY GLANDS FROM SJÖGREN’S SYNDROME PATIENTS

Background

Sjögren’s syndrome (SS) is a chronic autoimmune disease characterized by inflammation of the exocrine glands and severe symptoms of eye and mouth dryness. Disorders in the saliva secretion process have been associated with oxidative and endoplasmic reticulum (ER) stress in combination with inflammatory responses. The integrated stress response (ISR) is a mechanism that allows cells to modify their gene expression program to restore homeostasis and promote their survival against various extrinsic and intrinsic stress signals, such as hypoxia, nutrient deprivation, viral infections, inflammatory factors (cytokines, chemokines, inflammasomes), and accumulation of unfolded proteins in the ER, among others (1). The ISR is regulated by four kinases: PERK, PKR, HRI and GCN2, that dimerize and autophosphorylate to become active and each one responds to different stress stimuli. The signaling pathways that are activated in response to stress factors stimulate the phosphorylation of eIF2α, which causes a transient inhibition of global protein synthesis and induction of synthesis of some specific genes like ATF4 and NRF2. ATF4 induces the transcription of genes involved in metabolism and nutrient uptake, redox status, and regulation of apoptosis. Dephosphorylation of eIF2α is the ISR termination signal to restore protein synthesis and is mediated by the PP1 complex, which recruits the catalytic subunit PP1c and one of its two regulatory subunits: GADD34 or CREP.

Objectives

To evaluate the presence and functional state (phosphorylation) of the ISR sensing kinases: PERK, PKR, HRI and GCN2; the levels of eIF2α /p-eIF2α and the key ISR transcription factors ATF4 and NRF2, as well as subunits of the complex involved in the ISR termination: PP1c, GADD34 and CREP in labial salivary glands (LSG) of SS-patients.

Methods

Biopsies of LSG from 12 SS-patients and 11 control subjects were studied. The levels of mRNA, protein and phospho (p)-protein of the ISR components were determined by RT-qPCR and Western blotting.

Results

Our results show increased levels of p-PERK/PERK ratio (11/11), PKR (7/11), p-PKR (7/11), p-PKR/PKR ratio (7/11), eIF2α (5/11), p-eIF2α (5/11) and ATF4 (11/11) in LSG from SS-patients compared to control subjects. No significant changes were found in mRNA levels of HRI, GCN2, and GADD34 between LSG from SS-patients and control subjects. Decreased protein levels of HRI (8/12), p-GCN2 (6/11), eIF2α (6/11), p-eIF2α (6/11), NRF2 (11/12), and p-NRF2 (12/12) were found in LSG showing scarce parenchyma and high fibrosis and fat infiltration. On the other hand, PP1c and CREP showed decreased mRNA and protein levels in all SS-patients LSG. Interestingly, Ro autoantibodies and focus score were negatively correlated with PP1c and NRF2 mRNA and protein levels whereas positively correlated with PKR mRNA levels.

Conclusion

The overexpression and activation of some ISR kinases together with the decrease in the PP1c/CREP phosphatase complex suggests a continuous activation of ISR, resulting in p-eIF2α to remain activated in LSG from SS-patients. This would explain the high protein levels of ATF4 and of target genes involved in the antioxidant response in LSG from SS patients suggesting that ISR activation plays a key role in pro-survival response to cellular stress.

References

[1]Pakos-Zebrucka K, Koryga I, Mnich K, Ljujic M, Samali A, Gorman AM. The integrated stress response. EMBO Rep. 2016;17(10):1374-95.

Acknowledgements

This work was supported by Fondecyt-Chile 1210055; Enlace-VID Universidad de Chile [ENL04/20 to MJG]; Fondecyt Iniciacion 11201058 and PhD fellowship Conicyt Chile.

Disclosure of Interests

None declared

POS0455 TOFACITINIB DECREASES INFLAMMATORY MARKERS AND MITOCHONDRIAL MORPHOLOGICAL DAMAGE IN SALIVARY GLANDS OF A MURINE MODEL OF SJÖGREN’S SYNDROME

Background

Altered homeostasis of salivary gland (SG) epithelial cells in Sjögren’s syndrome (SS) patients could be the initiating factor that leads to inflammation, as well as secretory dysfunction. Mitochondria are important organelles involved in cellular metabolism and their dysfunction can induce a loss of homeostasis and inflammation. Altered mitochondrion can release mitochondrial components that can act as damage-associated molecular patterns (DAMPs) and induce an inflammatory response via pattern recognition receptors (PRRs) such as the NLRP3 inflammasome, TLR9, cGAS/STING, and ZBP1 (1). Previously we determined that SG from SS patients showed and altered autophagy, which is associated to an increased pro-inflammatory cytokines expression. Interestingly, increased expression of pro-inflammatory markers such as IL-6, was reversed by JAK inhibitor tofacitinib in three-dimensional (3D)-acini deficient in autophagy (2). It is not clear whether the alterations in autophagy found in SG patients include alterations in mitochondrial clearance (mitophagy) that may lead to the accumulation of damaged mitochondria and enhanced inflammation. In this context, recent results of our laboratory showed, for the first time, severe ultrastructural alterations of mitochondria in SG cells from SS patients (1). However, it remains to be determined if these alterations are related to inflammation and if an anti-inflammatory agent could regulate these processes.

Objectives

To analyze the effect of tofacitinib on the mitochondrial ultrastructure in submandibular glands of a murine model of SS. In addition, to evaluate the effect of tofacitinib on the expression and activation of some PRRs involved in the recognition of mitochondrial DAMPs in the same murine model.

Methods

Six-month-old female NOD.B10Sn-H2b/J mice (Jackson Laboratories, USA) were used with 4-5 mice per group. Procedures were approved by the Universidad de Chile Animal Care and Use Committee. 30 mg/kg/day tofacitinib citrate was administered by oral gavage. After 28 days of tofacitinib or vehicle administration, their submandibular glands were obtained, which were processed to evaluate the mitochondrial ultrastructure by electron microscopy or lysed in RIPA buffer to obtain proteins. The protein levels of PRRs: NLRP3, TLR9, ZBP-1, and cGAs, as well as molecules activated downstream of cGAS and ZBP-1 such as TBK1, pTBK1, pSTING, and STING were determined by Western blotting.

Results

The results show that the mitochondria of the glandular epithelial cells of NOD.B10Sn-H2b/J mice treated with vehicle (control) present alterations such as swelling, disruption of membranes and crest disorganization that previously were reported in patients with SS (1). Interestingly, tofacitinib treatment improves the architecture of mitochondria. On the other hand, the protein levels of PRRs such as NLRP3 and cGAS decreased in mice treated with tofacitinib, as well as pTBK1.

Conclusion

The altered morphology of mitochondria together with the increased protein levels of PRRs and downstream markers of these PRRs suggests release of mitochondrial DAMPs in submandibular glands of NOD.B10Sn-H2b/J mice. The improvement in mitochondrial morphology as well as the decrease in PRRs activation under tofacitinib treatment suggest a potential use of this anti-inflammatory agent in mitochondrial alterations associated with inflammation. Many questions remain to be addressed, such as determining which mitochondrial DAMP might be being released and whether this is associated with impaired mitochondrial function in SS.

References

[1]Barrera, M. J., et al (2021). Dysfunctional mitochondria as critical players in the inflammation of autoimmune diseases: Potential role in Sjögren’s syndrome. Autoimmunity reviews, 20(8), 102867.

[2]Barrera, M. J., et al (2021). Tofacitinib counteracts IL-6 overexpression induced by deficient autophagy: implications in Sjögren’s syndrome. Rheumatology (Oxford, England), 60(4), 1951–1962.

Acknowledgements

This work was supported by Fondecyt Iniciación 11201058 and Fondecyt-Chile 1210055.

Disclosure of Interests

None declared.

The Pbo Cluster from Pseudomonas syringae pv. Phaseolicola NPS3121 Is Thermoregulated and Required for Phaseolotoxin Biosynthesis

The bean (Phaseolus vulgaris) pathogen Pseudomonas syringae pv. phaseolicola NPS3121 synthesizes phaseolotoxin in a thermoregulated way, with optimum production at 18 °C. Gene PSPPH_4550 was previously shown to be thermoregulated and required for phaseolotoxin biosynthesis. Here, we established that PSPPH_4550 is part of a cluster of 16 genes, the Pbo cluster, included in a genomic island with a limited distribution in P. syringae and unrelated to the possession of the phaseolotoxin biosynthesis cluster. We identified typical non-ribosomal peptide synthetase, and polyketide synthetase domains in several of the pbo deduced products. RT-PCR and the analysis of polar mutants showed that the Pbo cluster is organized in four transcriptional units, including one monocistronic and three polycistronic. Operons pboA and pboO are both essential for phaseolotoxin biosynthesis, while pboK and pboJ only influence the amount of toxin produced. The three polycistronic units were transcribed at high levels at 18 °C but not at 28 °C, whereas gene pboJ was constitutively expressed. Together, our data suggest that the Pbo cluster synthesizes secondary metabolite(s), which could participate in the regulation of phaseolotoxin biosynthesis.

POS0180 TYPE I INTERFERON DEPENDENT HSA-MIR-145-5P DOWNREGULATION MODULATES MUC1 AND TLR4 OVEREXPRESSION IN SALIVARY GLANDS FROM PRIMARY SJÖGREN’S SYNDROME PATIENTS

Background:

Primary Sjögren’s syndrome (pSS) is an autoimmune and inflammatory disease that mainly affects the salivary glands (SG) and is characterized by an overactivation of the type I interferon pathway (IFNs I). IFNs I are known to regulate the levels of microRNAs (miRNAs), non-coding RNAs whose levels are altered in pSS. IFNs I can decrease the levels of miR-145-5p, a miRNA with anti-inflammatory roles that has been reported downregulated in SG of from pSS patients [1]. This miRNA has TLR4 and MUC1 transcripts as predicted targets. MUC1 and TLR4 are two proteins overexpressed in SG of pSS patients that contribute, through various mechanisms, to the inflammatory state and glandular dysfunction [2-3]. Thus, we propose that IFNs I may contribute to a self-perpetuating inflammation loop through a hsa-miR-145-5p dependent MUC1 and TLR4 overexpression in the SG of pSS patients.

Objectives:

to evaluate whether mRNA levels of MUC1 and TLR4 are modulated by hsa-miR-145-5p in a IFNs I dependent manner.

Methods:

13 pSS patients and 9 controls SG biopsies were analyzed. hsa-miR-145-5p levels were determined by TaqMan assays and MUC1, TLR4, IFN-α and IFN-β mRNA levels by RT-qPCR. Additionally, in vitro assays using type I IFNs and chemically synthesized hsa-miR-145-5p mimics and inhibitors were performed to study its effect on MUC1 and TLR4 expression. JAK1 and STAT1 mRNA levels were also measured.

Results:

By Taqman assays we validated the decreased hsa-miR-145-5p levels (p=0.0001) in SG of pSS patients compared to controls. The decreased hsa-miR-145-5p levels correlated inversely with the increased mRNA levels of IFN-β (p=0.0192) in SG of pSS-patients. The hsa-miR-145-5p downregulation also correlated inversely with the overexpression of its predicted targets MUC1 (p=0.010) and TLR4 (p=0.0004). In vitro assays showed that IFN-β induces the overexpression of JAK1 (<p=0.0001) and STAT1 (p=<0.0001) leading to the downregulation of hsa-mir-145-5p (p=<0.0001) and increased MUC1 (p=<0.0001) and TLR4 mRNA levels (p=<0.0001). Functional assays suggest a regulation of hsa-miR-145-5p on MUC1 and TLR4 expression as MUC1 and TLR4 mRNA levels were decreased in HSG cells transfected with hsa-miR-513c-3p mimic and increased in HSG cells transfected with the miRNA inhibitor.

Conclusion:

Our findings suggest that IFNs I could induce the downregulation of hsa-miR-145-5p leading to the overexpression of MUC1 and TLR4 in SG from pSS patients. TLR4 is activated by ectopic mucins in the SG extracellular matrix from pSS patients which induces pro-inflammatory cytokines secretion [3]. Furthermore, the high levels of the MUC1-SEC and MUC1-Y isoforms observed in SG from pSS patients may favor cytokine synthesis through the immuno-enhancing peptide of MUC1-SEC or through the formation of a MUC1-SEC/MUC1-Y complex [4]. Therefore, IFNs I may contribute to the development of SS through amplification and perpetuation of inflammation due to a hsa-miR-145-5p dependent MUC1 and TLR4 overexpression.

References:

[1]I. Alevizos, et al,. Arthritis Rheum, 2011;63:535-44.

[2]HH. Sung, et al,. Oral Dis. 2015;21(6):730-8.

[3]MJ. Barrera, et al,. Rheumatology (Oxford). 2015;54(8):1518-27

[4]LM. Herbert, et al,. Cancer Res. 2004;64(21):8077-84.

Acknowledgements:

Fondecyt 1210055, Fondecyt 1160015, Fondecyt Iniciación 11170049, Fondecyt Iniciación 11201058, CONICYT fellowship (DJ, PC)

Disclosure of Interests:

None declared

Effect of Metabolites Produced by Bacillus atrophaeus and Brevibacterium frigoritolerans Strains on Postharvest Biocontrol of Alternaria alternata in Tomato (Solanum lycopersicum L.)

In the present study, the antifungal activity of metabolites produced by Bacillus atrophaeus B5 and a new Brevibacterium strain against Alternaria alternata was evaluated. Assays in vitro and in vivo on tomato fruit during postharvest were made. Based on the 16S rDNA gene sequence analysis, the new strain (strain B7) was identified as Brevibacterium frigoritolerans. Metabolites produced by both bacterial strains reduced the spore germination of A. alternata in vitro and decreased the severity of the alternaria rot disease on tomato fruit during postharvest. This is the first report that demonstrates the potential of B. frigoritolerans B7 as a biocontrol agent against this fungal phytopathogen. The use of metabolites produced by B. atrophaeus B5 and B. frigoritolerans B7 represents a new approach to reduce the use of chemical pesticides and control fungal decay during the postharvest stage.

THU0229 HSA-MIR-513C-3P OVEREXPRESSION DECREASES XBP-1S CORRELATING WITH INCREASED INFLAMMATION AND AUTOANTIBODIES IN SALIVARY GLANDS FROM SJÖGREN’S SYNDROME PATIENTS

Background:

Endoplasmic reticulum (ER) stress and the Unfolded Protein Response (UPR) are linked to inflammation in a variety of human pathologies including autoimmune diseases. Salivary glands (SG) from Sjögren’s syndrome (SS) patients have high levels of IFN-gamma among other cytokines, which trigger or exacerbate protein unfolding or misfolding, inducing ER stress. In this study, we focused on the IRE1α/XBP-1 pathway of the UPR, whose transcription factor is XBP-1s, which induces genes linked to regulation of the secretory pathway. We recently found that SG of SS patients have reduced levels of XBP-1s transcripts associated with an increased DNA methylation of XBP-1 promoter [1]. We postulate that other epigenetic mechanisms, such as miRNAs, could coexist with promoter DNA hyper-methylation to regulate XBP-1s expression.

Objectives:

Due to hsa-miR-513c-3p overexpression has been reported in SG from SS patients [2] and that XBP-1 is a predicted target of hsa-miR-513c-3p, the aim of this study was to evaluate whether mRNA levels of XBP-1s is modulated by hsa-miR-513c-3p and also if IFN-gamma modify the expression hsa-miR-513c-3p and XBP-1s.

Methods:

SG biopsies from 16 SS-patients with low and high focus score and 5 controls were analyzed. hsa-miR-513c-3p levels were measured by Taqman miRNA assays, whereas XBP-1s mRNA levels were determined by qRT-PCR. Additionally,in vitroassays using IFN-gamma and chemically synthesized hsa-miR-513c-3p mimics and inhibitors were performed to study its effect on XBP-1s expression.

Results:

By Taqman assays we validated the overexpression of hsa-miR-513c-3p in SG from 8 SS patients with low (p=0.03) and 8 SS-patients with high (p=0.003) focus score, compared with SG from 5 controls. In the same samples, a decrease of XBP-1s transcript levels was observed in SG from SS-patients with low (p=0.002) and high (p=0.026) focus score. XBP1s transcript levels were negatively correlated with hsa-miR-513c-3p (r=-0.47, p=0.014), Ro (r=-0.73, p=0.0009), ANA (r=-0.7, p=0.0033) and focus score (r=-0.72, p=0.001). Stimulation of 3D-acini with 1 ng/mL IFN-gamma increase the hsa-miR-513c-3p levels (p=0.014) and decrease the XBP-1s transcript levels (p=0.027). A negative correlation was found between hsa-miR-513c-3p and XBP-1s transcript levels in 3D-acini stimulated with IFN-gamma (r=-0.87, p=0.0001). The XBP-1s transcript levels were decreased in HSG cells transfected with hsa-miR-513c-3p mimic and increased in HSG cells transfected with the miRNA inhibitor.

Conclusion:

IFN-gamma-induced upregulation of hsa-miR-513c-3p is consistent with the presence of STAT1-binding elements in its promoter region. Our findings suggest that the combined action of miRNAs and DNA methylation modulated by IFN-gamma could explain the altered expression of XBP-1s, a key transcription factor involved in cellular proteostasis, affecting secretory function in LSG from SS-patients. Our results confirm previous correlations found between XBP-1s protein levels and clinical parameters of SS-patients, suggesting an association of XBP-1s with inflammation and impaired SG function.

References:

[1]D. Sepúlveda,et al, Rheumatology (Oxford), 2018;57:1021-32.

[2]I. Alevizos,et al,. Arthritis Rheum, 2011;63:535-44.

Acknowledgments :

Fondecyt 1160015, Fondecyt Iniciación 11170049, Fondecyt Postdoctorado 3170023, CONICYT fellowship (PC, DJ).

Disclosure of Interests: :

None declared

Una región interpromotora incrementa la transcripción del gen argK, que codifica para la ornitina carbamoiltransferasa resistente a la faseolotoxina en Pseudomonas syringae pv. phaseolicola

Pseudomonas syringae pv. phaseolicola, es el agente causal del tizón del halo del frijol, una enfermedad que se caracteriza por presentar lesiones acuosas rodeadas por un halo clorótico, el cual es producido por la acción de la faseolotoxina, una toxina no específica del hospedero, producida de manera óptima entre 18°C a 20°C. Para protegerse de su propia toxina, P. syringae pv. phaseolicola posee una ornitina carbamoyl-transferasa (OCTasa) resistente a la faseolotoxina (ROCT) codificada por argK, que es expresada bajo las condiciones de síntesis de la faseolotoxina. El promotor de argK es divergente al promotor de phtABC y ambos comparten una región interpromotora. El objetivo del presente estudio fue evaluar la función de la región interpromotora sobre la transcripción de argK en P. syringae pv. phaseolicola. Para esto, se llevaron a cabo deleciones de la región interpromotora y se evaluó la transcripción de argK en un sistema heterólogo. También se determinó el efecto de múltiples copias de la región interpromotora sobre la producción de la faseolotoxina. Los resultados obtenidos  mostraron que  esta región es necesaria para incrementar la transcripción de argK. Adicionalmente, cuando se ponen múltiples copias de esta región, se interfiere con la termorregulación de la faseolotoxina a 28°C en la cepa de P. syringae pv. phaseolicola NPS3121.

Identification and characterization of a new Bacillus atrophaeus strain B5 as biocontrol agent of postharvest anthracnose disease in soursop (Annona muricata) and avocado (Persea americana)

Anthracnose is a fungal disease caused by Colletotrichum species that is detrimental to numerous fruit, including soursop and avocado. The use of fungicides to maintain the high quality of fruit creates a potential health risk. One alternative to this problem is the biological control, which has been applied successfully during postharvest. The Bacillus species are one of the most studied biological agents against postharvest pathogens because accomplish their biocontrol performance by producing a variety of metabolites. In this study, we evaluated the activity of metabolites contained in the cell free supernatant, obtained from Bacillus strain B5 culture, against micelial growth and spore germination of two virulent strains of C. gloeosporioides isolated from soursop and avocado. On the basis of 16S rDNA gene sequence analysis, this strain was identified as Bacillus atrophaeus. A preventive treatment using cell free supernatant, reduced severity and incidence of anthracnose disease on harvested soursop and avocado fruit. B. atrophaeus strain B5 harbors genes involved in the production of antibiotics such as surfactin, bacillomycin and iturin, which could be contributing to the efficiency of the preventive treatment during postharvest. The antagonistic role of metabolites contained in the cell free supernatant against anthracnose disease, provide a new approach by which to attack this problem and can help reduce the use of chemical pesticides, environmental pollution, leading to the safer fruit preservation.

Temperature-mediated biosynthesis of the phytotoxin phaseolotoxin by Pseudomonas syringae pv. phaseolicola depends on the autoregulated expression of the phtABC genes

Pseudomonas syringae pv. phaseolicola produces phaseolotoxin in a temperature dependent manner, being optimally synthesized between 18°C and 20°C, while no detectable amounts are present above 28°C. The Pht cluster, involved in the biosynthesis of phaseolotoxin, contains 23 genes that are organized in five transcriptional units. The function of most of the genes from the Pht cluster is still unknown and little information about the regulatory circuitry leading to expression of these genes has been reported. The purpose of the present study was to investigate the participation of pht genes in the regulation of the operons coded into the Pht cluster. We conducted Northern blot, uidA fusions and reverse transcription-PCR assays of pht genes in several mutants unable to produce phaseolotoxin. This allowed us to determine that, in P. syringae pv. phaseolicola NPS3121, genes phtABC are essential to prevent their own expression at 28°C, a temperature at which no detectable amounts of the toxin are present. We obtained evidence that the phtABC genes also participate in the regulation of the phtD, phtM and phtL operons. According to our results, we propose that PhtABC and other Pht product activities could be involved in the synthesis of the sulfodiaminophosphinyl moiety of phaseolotoxin, which indirectly could be involved in the transcriptional regulation of the phtA operon.

MUC1/SEC and MUC1/Y overexpression is associated with inflammation in Sjögren's syndrome

OBJECTIVES

To evaluate the expression and localization of MUC1/SEC and MUC1/Y isoforms in labial salivary glands (LSG) from Sjögren's syndrome patients (SS patients), as well as their in vitro expression induced by cytokines.

SUBJECTS AND METHODS

Labial salivary gland from 27 primary SS patients and 22 non-SS sicca subjects were studied. Relative MUC1/SEC and MUC1/Y mRNA levels were determined by qPCR and protein levels by Western blotting. Induction of mucin mRNAs was assayed in vitro. Immunohistochemistry was used for localization.

RESULTS

Relative MUC1/SEC and MUC1/Y mRNA and protein levels were significantly higher in LSG from SS patients. These mRNAs were induced by cytokines. MUC1/SEC and MUC1/Y were detected in acini apical region of control LSGs, and significant cytoplasmic accumulation was observed in acini of SS patients. MUC1/Y localized in acinar nuclei and cytoplasm of inflammatory cells of LSG from SS patients. A strong positive correlation was observed between cellular MUC1/SEC levels and glandular function determined by scintigraphy.

CONCLUSIONS

We show for the first time that MUC1/SEC and MUC1/Y are expressed in LSG of both SS patients and non-SS sicca subjects. The observed overexpression and aberrant localization of MUC1/SEC and MUC1/Y and their induction by pro-inflammatory cytokines may favor the perpetuation of the inflammatory environment that disrupts the salivary glandular homeostasis in SS patients.

High-peak-power pulse generation from a monolithic master oscillator power amplifier at 1.5 μm

We present an experimental study on the generation of high-peak-power short optical pulses from a fully integrated master-oscillator power-amplifier emitting at 1.5 μm. High-peak-power (2.7 W) optical pulses with short duration (100 ps) have been generated by gain switching the master oscillator under optimized driving conditions. The static and dynamic characteristics of the device have been studied as a function of the driving conditions. The ripples appearing in the power-current characteristics under cw conditions have been attributed to mode hopping between the master oscillator resonant mode and the Fabry-Perot modes of the entire device cavity. Although compound cavity effects have been evidenced to affect the static and dynamic performance of the device, we have demonstrated that trains of single-mode short optical pulses at gigahertz frequencies can be conveniently generated in these devices.

Gene expression of Pht cluster genes and a putative non-ribosomal peptide synthetase required for phaseolotoxin production is regulated by GacS/GacA in Pseudomonas syringae pv. phaseolicola

Pseudomonas syringae pv. phaseolicola is the causal agent of halo blight disease of beans (Phaseolus vulgaris L.), which is characterized by watersoaked lesions surrounded by a chlorotic halo resulting from the action of a non-host specific toxin known as phaseolotoxin. This toxin inhibits the enzyme ornithine carbamoyltransferase involved in the arginine biosynthesis pathway. It was previously reported that genes within the Pht cluster were involved in the regulation and synthesis of phaseolotoxin. The GacS/GacA two-component signal transduction system controls important pathogenicity and virulence mechanisms in several Gram-negative bacteria. Tox(-) phenotype gacA(-) and gacS(-) mutants were obtained and gacA(-) transcriptome analysis revealed that this response activator controls expression of genes within the Pht cluster as well as another gene located in a different region in the bacterial chromosome and that has been unambiguously shown to be directly involved in phaseolotoxin biosynthesis. Results presented in this work suggest that phaseolotoxin biosynthesis involve elements within and outside the Pht Cluster, and that the GacS/GacA two-component system exerts control over them.

[Generalized epileptic seizures in an infant due to passive exposure to cocaine]

BACKGROUND

The differential diagnosis of afebrile seizures in the first year of life is extensive.

CASE REPORT

A 7-month old infant presented two afebrile generalized tonic-clonic seizures in 23 hours; her psychomotor and growth development followed a normal course. Laboratory analysis, cerebral echography and electroencephalogram were normal. Urine toxicology was positive for cocaine on two occasions. A negative urine sample was obtained 48 hours later. The parents denied drug abuse but explained a recent exposure to smoke some hours before the episode. The patient had no seizures in the following six months, with normal psychomotor development.

DISCUSSION

Passive inhalation of cocaine is associated with seizures in infants. There is no perception of the risk of passive exposure to cocaine in our country, despite the increasing consumption of crack in young adults. Urine toxicology should be systematically included in the study of a first afebrile seizure in an infant.

Normal neurological outcome after congenital thyrotoxicosis: prognostic value of observation of general movements

We followed up a patient born preterm with congenital thyrotoxicosis by observing her general movements (GMs) in accordance with Prechtl's method. Initially a chaotic pattern was observed. Along with the normalization of thyroid hormones, the GM pattern changed to a poor repertoire at four weeks of life, full-blown writhing movements at six weeks and fidgety movements at the age of four months. This is the first report of chaotic GMs in a neonate reflecting transient neurological dysfunction related to congenital thyrotoxicosis, with subsequent normal neurological and cognitive outcome.

Severe alterations in expression and localisation of {alpha}6{beta}4 integrin in salivary gland acini from patients with Sjogren syndrome

OBJECTIVES

In salivary glands from patients with Sjögren syndrome, overexpression of laminins 1 and 5 and disorganisation of the acinar basal lamina have been reported. Laminin 5 mediates association of the basal lamina with epithelial cells by forming adhesion complexes upon interaction with alpha6beta4 integrin. In the present work, mRNA and protein levels of alpha6beta4 integrin were determined and its localisation in salivary glands evaluated in patients with Sjögren syndrome.

METHODS

Salivary glands of 12 patients with Sjögren syndrome and 8 controls were studied. The mRNA and protein levels of alpha6beta4 were determined by semiquantitative reverse transcriptase (RT)-PCR and western blot analysis, respectively. The subcellular localisation of alpha6beta4 and laminin were evaluated by confocal microscopy.

RESULTS

In patients, no significant differences in alpha6 and beta4 mRNA levels were detected. However, beta4 integrin protein levels were significantly lower, whereas, changes in alpha6, were highly variable. In controls, alpha6beta4 was detected in the basolateral and basal surface of serous and mucous acini, respectively. In patients, alterations in alpha6beta4 distribution were particularly dramatic for acini with strong basal lamina disorganisation. alpha6beta4 was also detected in the cytoplasm and lateral plasma membrane in serous and mucous acini.

CONCLUSION

Mild alterations in the basal lamina correlated with lateral redistribution of alpha6beta4 integrin and the formation of new cell-cell adhesions that help maintain acinar organisation and promote cell survival. Conversely, in cases with severe basal lamina alterations, lateral alpha6beta4 redistribution was no longer sufficient to maintain acinar cell survival. Thus, maintenance of equilibrium between cell-cell and cell-basal lamina attachment is required to sustain gland cell survival.

Functional characterization of the gene cluster from Pseudomonas syringae pv. phaseolicola NPS3121 involved in synthesis of phaseolotoxin

Pseudomonas syringae pv. phaseolicola is the causal agent of halo blight disease of beans (Phaseolus vulgaris L.), which is characterized by water-soaked lesions surrounded by a chlorotic halo resulting from the action of a non-host-specific toxin known as phaseolotoxin. This phytotoxin inhibits the enzyme ornithine carbamoyltransferase involved in arginine biosynthesis. Different evidence suggested that genes involved in phaseolotoxin production were clustered. Two genes had been previously identified in our laboratory within this cluster: argK, which is involved in the immunity of the bacterium to its own toxin, and amtA, which is involved in the synthesis of homoarginine. We sequenced the region around argK and amtA in P. syringae pv. phaseolicola NPS3121 to determine the limits of the putative phaseolotoxin gene cluster and to determine the transcriptional pattern of the genes comprising it. We report that the phaseolotoxin cluster (Pht cluster) is composed of 23 genes and is flanked by insertion sequences and transposases. The mutation of 14 of the genes within the cluster lead to a Tox(-) phenotype for 11 of them, while three mutants exhibited low levels of toxin production. The analysis of fusions of selected DNA fragments to uidA, Northern probing, and reverse transcription-PCR indicate the presence of five transcriptional units, two monocistronic and three polycistronic; one is internal to a larger operon. The site for transcription initiation has been determined for each promoter, and the putative promoter regions were identified. Preliminary results also indicate that the gene product of phtL is involved in the regulation of the synthesis of phaseolotoxin.

Patterns and variability in electrophoretic polypeptide profiles of human saliva in a healthy population

Electrophoretic polypeptide profiles of normal human saliva differ markedly between different reports. Since both methodological variations and polymorphism may explain these differences, in this study we aimed to establish whether or not the salivary electrophoretic polypeptide profiles of subjects from a healthy population share discrete molecular features. To this end, parotid, submandibular/sublingual and whole salivas were collected separately from each of 40 young and 34 elderly clinically healthy adults and processed for SDS-polyacrylamide gel electrophoresis and Coomassie blue staining. Each type of glandular saliva displayed a different group of invariant (i.e. present in every subject) electrophoretic polypeptide bands while whole saliva showed a profile that reflected mostly the combined contribution of the major salivary glands. Some minor variant (i.e. absent in some subjects) bands were identified in each type of saliva. Regarding those interindividual variations, no age- or sex-dependence was appreciated. Altogether, these results demonstrate the occurrence of distinctive electrophoretic polypeptide patterns, in addition to some minor variations, for each type of normal saliva, thus providing a background for further populational studies on salivary polypeptide profiles.

Basal lamina disorganisation of the acini and ducts of labial salivary glands from patients with Sjogren's syndrome: association with mononuclear cell infiltration

OBJECTIVE

To study the expression of laminin and type IV collagen as biomarkers of the organisation of the basal lamina of acini and ducts in labial salivary glands from patients with Sjögren's syndrome, and to relate this organisation to inflammatory cell invasion of acini and ducts.

METHODS

Immunohistochemistry for laminin and type IV collagen was undertaken on sections of labial salivary glands from 30 patients with Sjögren's syndrome, 10 control subjects, and 24 controls with chronic sialoadenitis. Immunohistochemistry reaction, alterations to cell morphology, and the presence of inflammatory cells in acini and ducts were evaluated and scored using a semiquantitative method.

RESULTS

Changes in the expression of laminin and type IV collagen in the basal lamina of acini and ducts of labial salivary glands from patients with Sjögren's syndrome were more pronounced than in labial salivary glands from control groups. A remarkable characteristic was the disorganisation of the basal lamina in the labial salivary glands in Sjögren's syndrome. The pattern of immunoreactivity of the basal lamina of other structures (for example, blood vessels) did not change. In Sjögren's syndrome, invasion of cytotoxic T lymphocytes was only observed in acini and ducts which had a disorganised basal lamina.

CONCLUSIONS

The high state of disorganisation of the basal lamina of acini and ducts could allow invasion of cytotoxic T lymphocytes in Sjögren's syndrome, contributing to cell death and ductal hyperplasia.

Essential residues in the chromate transporter ChrA ofPseudomonas aeruginosa

The chrA gene of Pseudomonas aeruginosa plasmid pUM505 encodes the hydrophobic protein ChrA, which confers resistance to chromate by the energy-dependent efflux of chromate ions. Chromate-sensitive mutants were isolated by in vivo random mutagenesis. Transport experiments with cell suspensions of selected mutants showed that 51CrO4(2-) extrusion was drastically lowered as compared to suspensions of the strain with the wild-type plasmid, confirming that the mutations affected a chromate efflux system. DNA sequence analysis showed that most point mutations affected amino acids clustered in the N-terminal half of ChrA, altering either cytoplasmic regions or transmembrane segments, and replaced residues moderately to highly conserved in ChrA homologs. PhoA and LacZ translational fusions were used to confirm the membrane topology at the N-terminal half of the ChrA protein.

Differential expression of matrix metalloproteinases in labial salivary glands of patients with primary Sjögren's syndrome

OBJECTIVE

To determine the enzymatic activity and cellular localization of matrix metalloproteinases (MMPs) 2, 3, and 9 in labial salivary glands from patients with different degrees of severity of primary Sjogren's syndrome (primary SS).

METHODS

Gelatinase activity was determined by zymography and quantified by densitometry. The specificity of MMPs was determined using protease inhibitors and chelators, as well as activators of the latent forms of these enzymes. The cellular localization of MMPs was carried out using monoclonal antibodies that recognize their latent and active forms.

RESULTS

Labial glands from control subjects and patients showed gelatinase activity for MMP-2 and MMP-9. Activation studies revealed that both enzymes were predominantly present in their latent forms. The highest levels of MMP-9 activity were detected in patients with severe, active, primary SS (except for patients with severe clinical symptoms for extended periods) and correlated with structural and functional glandular changes. MMP-2 activity was almost the same in patients and controls. MMPs were detected by immunolocalization only in acinar and ductal cells and were homogeneously distributed throughout patients' glands. MMP-2 and MMP-9 expression paralleled their gelatinase activity. MMP-3, detectable only with immunologic methods, was absent in control subjects but abundantly expressed in patients. Importantly, MMP protein levels in acinar and ductal cells were independent of either the presence or the proximity of mononuclear infiltrate cells.

CONCLUSION

MMP-3 and MMP-9 expression, as well as MMP-9 catalytic activity, were increased in tissue samples from SS patients in a manner that correlated with the severity of the disease. Most important, increased MMP activity stemmed from exocrine epithelial cells and was not due to infiltrating lymphocytes. Thus, changes in salivary glands as a consequence of proteolysis may lead to severe glandular destruction.

[Salivary gland scintigraphy en Sjogren syndrome and its relation with the result of lip biopsy. Comparative study with a control population]

BACKGROUND

Salivary gland scintigraphy allows a non invasive, morphological and functional assessment of parotid and submaxillary salivary glands.

AIM

To describe the main features of salivary gland scintigraphy in patients with Sjögren syndrome, rheumatic fibromyalgia and normal controls and compare the results with lip biopsy.

PATIENTS AND METHODS

Sixty one normal controls, 66 patients with Sjögren syndrome and 18 patients with rheumatic fibromyalgia were studied. For the diagnosis of Sjögren syndrome and fibromyalgia rheumatica, the Modified European and American College of Rheumatology criteria were used, respectively. Lip biopsies were obtained in 52 patients with Sjögren syndrome. Scintigraphy was done with a gamma camera and computer after the administration of 99mTc-pertechnetate, obtaining images during 30 min and creating time/activity curves. Scintigraphy was classified as normal, with mild or severe alterations.

RESULTS

Scintigraphy was normal in 74% of control subjects and in 26%, it had mild alterations. In 72% of patients with rheumatic fibromyalgia, scintigraphy was normal whereas in 28%, it had mild alterations. In 27% of patients with Sjögren syndrome, scintigraphy was normal, in 27% it had mild alterations and in 46%, severe alterations. There was a positive and significant correlation between pathological alterations of salivary glands and scintigraphic alterations (r = 0.642, p < 0.001).

CONCLUSIONS

Severe scintigraphic alterations of salivary glands strongly support the diagnosis of Sjögren syndrome. Mild alterations are non specific and a normal scintigraphy does not exclude the diagnosis.

[Standardization of ELISA IgM and IgA for immunodiagnosis of human trichinosis]

An ELISA test for trichinosis using as antigen a larvae soluble fraction from Trichinella spiralis was carried out for the detection of IgM and IgA specific antibodies in 45 serum samples from patients confirmed or suspected to have trichinosis by strong clinical and epidemiological evidences. All the patients had positive serology detected by precipitin test, bentonite floculation test, indirect hemagglutination test and ELISA IgG test. The cut-off value was determined using two criteria. Criterion A was determined in each plate, using three positive controls and two negative ones; the average of the negative controls and the weakest positive control, multiplied by a 1.2 factor was, considered the cut-off value. Criterion B was determined using the average plus three standard deviations from 64 apparently healthy persons serum samples. In both cases, three serum dilutions (1:10, 1:100 and 1:500) were used. The sensitivity of ELISA IgM was 100.0, 93.3 and 82.2% using serum dilutions of 1:10, 1:100 and 1:500 respectively (criterion A) and 100.0, 97.8 and 95.6% for the same dilutions (criterion B), whereas the values for ELISA IgA were: 100.0, 91.1 and 86.7% (criterion A) and 100.0, 100.0 and 91.1% (criterion B). In order to find out the specificity of ELISA IgM and ELISA IgA, additional 118 serum samples from individuals with other parasitoses, such as cysticercosis (18) hydatidosis (39), fascioliasis (12), toxocariasis (30), Chagas' disease (12) and individuals with non-specific eosinophilia (7), were also tested. ELISA IgM presented a specificity of 92.3, 93.4 and 97.3% (criterion A) and 96.2, 97.8 and 97.8% (criterion B) whereas the results for ELISA IgA were 97.8, 98.9 and 99.4% (criterion A) and 98.4% for the 1:10 and 1:100 dilutions and 100.0% for the 1:500 dilution (criterion B). The positive predictive values of ELISA IgM were 76.3, 77.8 and 88.1% (criterion A) and 86.5, 91.7 and 91.5% (criterion B) whereas the negative ones were 100.0, 98.3 and 95.7% (criterion A) and 100.0, 99.4 and 98.9% (criterion B). The positive predictive values of ELISA IgA were 91.8, 95.3 and 97.5% (criterion A) and 93.8, 93.8 and 100.0% (criterion B) whereas the negatives ones were: 100.0, 97.8 and 96.8% (criterion A) and 100.0, 100.0 and 97.8% (criterion B). The use of ELISA IgM and ELISA IgA in the immunodiagnosis of trichinosis is discussed.

[Protein diffusion patterns in human saliva]

BACKGROUND

There are two modes of saliva protein diffusion on a cellulose flat matrix. The monophasic mode of diffusion consists in a homogeneous distribution of salivary protein components on the matrix. On the contrary, in the biphasic mode, an area occupied by nondiffusible proteins is surrounded by an area occupied by diffusible proteins.

AIM

To study protein diffusion patterns of saliva obtained from normal human volunteers.

MATERIAL AND METHODS

Saliva was obtained from 33 subjects aged 67.5 +/- 12 years old (29 female). Forty microliters of saliva were deposited in the center of cellulose disks for protein diffusion assays.

RESULTS

Thirty three whole saliva samples and 31 submandibular/sublingual samples showed a biphasic diffusion pattern. On the contrary, 62 out of 66 samples of parotid saliva displayed a monophasic diffusion pattern. In one parotid saliva samples and 2 submandibular/sublingual samples, the diffusion pattern could not be established. Patterns of salivary protein diffusion were highly consistent within the same individual. Eighty percent of subjects had an unequivocal pattern of saliva protein diffusion.

CONCLUSIONS

The monophasic mode of saliva protein diffusion is a feature of parotid saliva, whereas the biphasic mode is characteristic of submandibular/sublingual and whole saliva.

[Distal renal tubular acidosis and nephrolithiasis in 3 cases of primary Sjögren syndrome]

Tubulo interstitial nephritis, the main manifestation of renal involvement in Sjögren syndrome, may lead to a tubular dysfunction that is usually subclinical. We report three women, aged 32, 35 and 35 years old, with a primary Sjögren syndrome and symptomatic type I or distal tubular acidosis. Two patients had nephrolithiasis and one a nephrocalcinosis. Two had a basal hyperchloremic metabolic acidosis. The ammonium chloride acidification test was abnormal in all, demonstrating a distal tubular defect. None had proximal tubular dysfunction. All had an urinary pH over 6.5 and hypocitraturia and none had hypercalciuria. Renal calculi were composed of calcium oxalate and calcium phosphate in two patients and calcium phosphate and ammonium phosphate in the other. All women had positive antinuclear antibodies with mottled pattern, two had anti Ro antibodies and positive rheumatoid factor and one had hypergammaglobulinemia. None had anti La antibodies, crioglobulinemia or monoclonal proteins.

[Synovial chondromatosis: review of 25 monoarticular cases]

We report 25 patients (20 female) aged 34 to 74 years old, with monoarticular synovial chondromatosis. Affected joints were the knee in 25 cases, the ankle in one case and the elbow in one case. Chronic articular pain was the main symptom, followed by swelling, limitation in motion range, free palpable bodies and symptomatic popliteal cysts. X ray examination showed free calcified osteochondroid bodies in 48% of patients and secondary osteoarthritis in 36%. Bone scintiscan showed an increased focal uptake. All pathological samples had chondroid or osteochondroid nodules; 64% had small blood vessels, thickened with concentric collagen laminae and 20% had isolated chondrocytes. Malignant degeneration was not observed. Surgical or artroscopic synovectomy was the procedure of choice in 20 knees. In the affected elbow and ankle, extraction of free bodies was the sole procedure. No recurrences were observed. It is concluded that synovial chondromatosis must be considered in the differential diagnosis of chronic articular pain and monoarthritis.

[Radiation synovectomy with yttrium 90 and rhenium 186 in rheumatoid arthritis, long term follow-up and effects on synovial membrane]

Despite the progress in the treatment of rheumatoid arthritis (RA), many patients continue to suffer from persistent and painful synovitis. We assessed the clinical results of 64 intraarticular injections of Yttrium 90 in the knee and 56 injections of Rhenium 186 in the wrist in 71 patients with RA, older than 40 years, without relief of synovitis after six months of systemic or local treatment and with a radiological stage I or II of their joints. We obtained good results in 75% of knees and 100 of wrists during a follow up period of 8 to 60 months. A repeated histological examination of the synovial membrane of 14 joints in which good results were obtained disclosed a reduction in inflammation and transitory synovial cell hyperplasia that ended in a dense fibrosis. It is concluded that radiation synovectomy continues to be an effective therapy for selected patients with RA and synovitis. The observed histopathological changes may aid the interpretation of magnetic resonance imaging of the treated joints.

[Migratory regional osteoporosis. Effect of treatment with calcitonin. Report of 2 cases]

We report two cases of regional migratory osteoporosis. One is a 41 years old male, with the classical form, presenting with successive episodes of painful osteoporosis lasting for 5 months at the hip, knee and distal epiphysis of the right metatarsophalangeal joints. The second case is a 40 years old female presenting with an unusual disseminated form, lasting for 30 months, with successive and simultaneous episodes of polyarticular and costal painful osteoporosis. An increased bone fraction of serum alkaline phosphatases and urine hydroxyproline/creatinine and calcium/creatinine ratios were detected. Imaging showed localized periarticular or costal osteoporosis. Bone biopsies disclosed a severe osteopenia with accelerated bone reabsorption. Bone scintigraphy precociously detected location, migration and evolution of lesions. Patients were treated with subcutaneous calcitonin, 100 U/day during 1 month and on alternative days posteriorly; this treatment alleviated pain but did not prevent the appearance of new crisis. Our observations suggest that regional migratory osteoporosis presentation may range from oligoarticular to disseminated forms and that calcitonin has a precocious and persistent analgesic effect.

Effects of cyclosporine on tubular acidification function in patients with idiopathic uveitis

Renal tubular acidification function was studied in 12 patients treated with cyclosporine (Cy) for idiopathic uveitis (IU) and in 5 patients with IU not treated with Cy. After intravenous bicarbonate loading fractional bicarbonate excretion was similar in both groups indicating normal proximal tubular acidification function. Plasma renin activity, plasma aldosterone and transtubular potassium gradient were similar in both groups. Distal hydrogen ion secretion evaluated by the ability to increase urine-blood (U-B) pCO2 in a highly alkaline urine was impaired in Cy-treated patients (31.8 +/- 3.2 mm Hg) as compared to controls (47.9 +/- 0.5 mm Hg) (p < 0.005). We conclude that Cy therapy is associated with a distal acidification defect with a low U-B pCO2 gradient during sodium bicarbonate loading. Because none of our Cy-treated patients spontaneously developed over metabolic acidosis one could classify them as having an incomplete form of distal tubular acidosis.