Relapse in patients with antineutrophil cytoplasmic antibody-associated vasculitis undergoing dialysis: a single-centre retrospective study in South Korea

OBJECTIVES

The disease activity of antineutrophil cytoplasmic antibody-associated vasculitis (AAV) can decrease after dialysis, and relapse after dialysis is not well-studied. We investigated the clinical manifestations and factors associated with relapse in patients with AAV undergoing dialysis.

METHODS

This retrospective study included data of patients with AAV undergoing dialysis due to renal involvement from July 2005 to March 2021 in a single tertiary centre in Seoul, Korea. Cox regression analysis was performed to identify relapse-associated factors.

RESULTS

The study cohort included 38 patients with a median age of 64.0 years; 28 (73.7%) were female, and 35 (92.1%) patients were diagnosed with microscopic polyangiitis (MPA). At diagnosis, the mean Birmingham vasculitis activity score (BVAS) was 18.3 and 66.3% of the patients exhibited pulmonary manifestations. During follow-up, 12 patients experienced AAV relapse, including nine patients with diffuse alveolar haemorrhage (DAH), two patients with aggravated interstitial lung disease, and one patient with DAH accompanied with neuropathy. Clinical features including age, sex, and baseline BVAS did not significantly differ between the relapse and non-relapse groups. By univariable analysis, lung infiltration, DAH, corticosteroid pulse therapy for induction, and mean corticosteroid dose were significantly associated with relapse. Multivariable analysis revealed that DAH (adjusted hazard ratio 5.509, 95% CI 1.569-19.339; P=0.008) and mean corticosteroid dose (adjusted hazard ratio 1.381, 95% CI 1.161-1.642; P<0.001) were significantly associated with relapse.

CONCLUSIONS

In patients with AAV undergoing dialysis, DAH and mean corticosteroid dose were significantly associated with relapse, highlighting the importance of close monitoring.

Recovery and long-term renal outcome of patients with anti-neutrophil cytoplasmic antibody-associated vasculitis who are on dialysis at presentation

Objective

Renal involvement in anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) can lead to severe renal dysfunction requiring dialysis at diagnosis. We aimed to study the clinical and pathologic characteristics of patients with AAV dependent on dialysis at presentation and the long-term renal outcomes of patients who recovered from dialysis.

Methods

This retrospective study analyzed data of patients diagnosed with AAV who were on dialysis from July 2005 to May 2021 at a single tertiary center in Korea.

Results

Thirty-four patients were included in the study (median age 64.5 years, females 61.8%), of which 13 discontinued and 21 continued dialysis. The proportion of normal glomeruli (p<0.001) and interstitial fibrosis (p=0.024) showed significant differences between both groups. Multivariable analysis showed that the proportion of normal glomeruli was associated with dialysis discontinuation (odds ratio=1.29, 95% confidence interval 0.99~1.68, p=0.063), although without statistical significance. Treatment modalities, including plasmapheresis, did not show significance with dialysis discontinuation. In the follow-up analysis of 13 patients who had discontinued dialysis for a median of 81 months, 12 did not require dialysis, and their glomerular filtration rate values significantly increased at follow-up time compared to when they stopped dialysis (37.5 [28.5~45.5] vs. 24.0 [18.5~30.0] mL/min/1.73 m²; p=0.008).

Conclusion

Approximately 38% of AAV patients on dialysis discontinued dialysis, and the recovered patients had improved renal function without dialysis during longer follow-up. Patients with AAV on dialysis should be given the possibility of dialysis discontinuation and renal recovery, especially those with normal glomeruli in kidney pathology.

When MRI would be useful in patients without evidence of sacroiliitis on radiographs?

We aimed to identify when magnetic resonance imaging (MRI) would be useful to diagnose patients with suspected axial spondyloarthropathy (AxSpA) without evidence of sacroiliitis on radiographs. We retrospectively reviewed electronic medical records of patients who underwent pelvis MRI after radiographs at the rheumatology clinic in a single tertiary center in Korea. Patients underwent imaging from January 2020 to July 2022. We collected data including complete blood count, erythrocyte sedimentation rate, C-reactive protein (CRP), human leukocyte antigen (HLA)-B27, history of acute anterior uveitis (AAU), peripheral arthritis, dactylitis, inflammatory bowel disease (IBD), enthesopathy, and psoriasis. A total of 105 patients who showed no evidence of sacroiliitis on radiographs were included. The median age of patients was 41.0 years, and 44.8% were male. Of them, 34 showed sacroiliitis on MRI (group 1), and 71 showed no evidence of sacroiliitis even on MRI (group 2). Known AxSpA-related clinical features including AAU, peripheral arthritis, dactylitis, IBD, enthesopathy, and psoriasis were not different between the two groups. HLA-B27 positivity (79.4% vs. 40.0%, p < 0.001), median white blood cell count (7700 vs. 6300, p = 0.007), mean platelet count (307.7 ± 69.7 vs. 265.3 ± 68.9 × 103/µL, p = 0.005), and median CRP level (0.38 vs. 0.10, p = 0.001) showed significant differences between the two groups. In a multivariate analysis, HLA-B27 positivity and platelet count were significantly associated with sacroiliitis on MRI. In our cohort, sacroiliitis was observed on MRI in one-third of patients without radiographic evidence. MRI could be recommended to evaluate sacroiliitis in patients with positive HLA-B27 and a high platelet count.

Prognostic value of proteinuria monitoring in anti-neutrophil cytoplasmic antibody-associated vasculitis

OBJECTIVE

To determine the prognostic significance of proteinuria monitoring in patients with anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV).

METHODS

We retrospectively analyzed the data of kidney biopsy-confirmed patients with AAV. Proteinuria was evaluated by a urine dipstick test. Poor renal outcome was defined as stage 4/5 chronic kidney disease (CKD) (estimated glomerular filtration rate < 30 mL/min/1.73 m2).

RESULTS

We enrolled 77 patients with a median follow-up duration of 36 months (interquartile range, 18-79) in this study. Excluding 8 patients on dialysis at 6 months, 59/69 (85.5%) achieved remission after induction therapy. Patients were then divided into two groups according to the presence of proteinuria at 6 months after induction therapy (n = 29 with proteinuria, 40 without proteinuria). There was no significant difference in the rate of relapse or death according to the presence of proteinuria (p = 0.304 relapse, 0.401 death). In contrast, patients with proteinuria had significantly lower kidney function than those without proteinuria (41 vs. 53.5 mL/min/1.73 m2, p = 0.003). Multivariate analysis revealed that eGFR values at 6 months (hazard ratio [HR] 0.925; 95% CI 0.875-0.978, p = 0.006) and proteinuria at 6 months (HR 4.613; 95% CI 1.230-17.298, p = 0.023) were significantly associated with stage 4/5 CKD.

CONCLUSION

The presence of proteinuria at 6 months after induction therapy and low renal function was significantly associated with a higher risk of stage 4/5 CKD in patients with AAV. Monitoring for proteinuria after induction therapy may help predict poor renal outcomes in patients with AAV.

Integrated genomic approaches identify upregulation of SCRN1 as a novel mechanism associated with acquired resistance to erlotinib in PC9 cells harboring oncogenic EGFR mutation

Therapies targeting the tyrosine kinase activity of Epidermal Growth Factor Receptor (EGFR) have been proven to be effective in treating a subset of non-small cell lung cancer (NSCLC) patients harboring activating EGFR mutations. Inevitably these patients develop resistance to the EGFR-targeted tyrosine kinase inhibitors (TKIs). Here, we performed integrated genomic analyses using an in vitro system to uncover alternative genomic mechanisms responsible for acquired resistance to EGFR-TKIs. Specifically, we identified 80 genes whose expression is significantly increased in the erlotinib-resistant clones. RNAi-based systematic synthetic lethal screening of these candidate genes revealed that suppression of one upregulated transcript, SCRN1, a secernin family member, restores sensitivity to erlotinib by enhancing inhibition of PI3K/AKT signaling pathway. Furthermore, immunohistochemical analysis revealed increased levels of SCRN1 in 5 of 11 lung tumor specimens from EGFR-TKIs resistant patients. Taken together, we propose that upregulation of SCRN1 is an additional mechanism associated with acquired resistance to EGFR-TKIs and that its suppression serves as a novel therapeutic strategy to overcome drug resistance in these patients.

Influence of a ring-shaped pump beam on temperature distribution and thermal lensing in end-pumped solid state lasers

A simple method for reducing thermal lensing in an end-pumped solid state laser using a ring-shaped pump beam is reported. Analytical expressions for the temperature distribution and the thermal lensing focal length in a laser medium end-pumped by a beam with a ring-shaped intensity profile are derived. The results indicate that thermal effects including thermal lensing can be significantly reduced due to a more uniform temperature distribution. This approach has been applied to a Nd:YVO₄ amplifier operating at 1064 nm confirming that the brightness of the output beam can be remarkably improved at high power levels due to the better beam quality for the ring-shaped pumping compared to the conventional quasi-top-hat pumping. The prospects for power scaling and further improvement in laser performance will be discussed.

Analysis of comedone, sebum and porphyrin on the face and body for comedogenicity assay

BACKGROUND/PURPOSE

Many ingredients used in cosmetics evoke a comedogenic response. Rabbit ear model (REM) is a useful method that can replace human in examining materials and products in early developmental stage. However, a number of studies pointed out its disadvantage that it overreacts to comedogenic materials. The purpose of this study was to find the most appropriate region for evaluating comedogenicity in human skin.

METHODS

Sixty-six female subjects (age 32.48 ± 10 years; range 20-52 years) with mild to moderate facial acne lesions were included in this study. The whole face, upper chest, and back of volunteers were photographed. Lesion (closed and open comedones) counting, instrumentation of sebum secretion level, and analysis of porphyrin number were performed. The entire study was performed under environmental conditions of specific relative temperature and humidity, controlled and maintained identically for each volunteer.

RESULTS

In case of closed comedone, forehead showed a significant correlation with frontal cheek, lateral cheek, chin, and upper back. Meanwhile, significant correlations were observed between frontal cheek and chin as well as lateral cheek and chest. As for open comedone, forehead showed a significant correlation with chin site. A significant correlation was also observed between front cheek and lateral cheek as well as between upper chest and back. Analyzing the correlation between the occurrence of comedones and sebum in each region, a significant correlation between closed comedone and sebum was observed in frontal and lateral cheek. Analyzing the correlation between the occurrence of comedones and porphyrine in each region, a significant correlation between open comedone and porphyrin was observed in chin.

CONCLUSION

When evaluating the comedogenicity of cosmetics ingredients or products, this study recommends using both of the methods of testing on back and directly testing on face according to the characteristics of the materials. In case of mild potent ingredients or products in particular, verification through usability test that the directly test on face will help securing reliability.

Alterations in AMPA receptor phosphorylation in the rat striatum following acute and repeated cocaine administration

Protein phosphorylation is an important mechanism for the posttranslational modulation of ionotropic glutamate receptors and is subject to regulation by changing synaptic inputs. In this study, we investigated the regulation of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor GluR1 subunit phosphorylation by cocaine exposure in the rat dorsal striatum in vivo. We found that acute cocaine challenge followed by 6 days of repeated systemic injections of cocaine (20 mg/kg once daily) enhanced the sensitivity of the GluR1 subunit in its phosphorylation at serine 831 (Ser831) in the dorsal striatum. This enhancement of the sensitivity of Ser831 phosphorylation was reduced, at the receptor and ion channel level, by blocking (1) group I metabotropic glutamate receptors (mGluRs), (2) N-methyl-D-aspartate receptors, and (3) L-type voltage-operated Ca(2+) channels. Similar reduction of the enhancement was also induced, at the protein kinase level, by inhibiting (1) protein kinase C, (2) calcium/calmodulin-dependent protein kinases, and (3) c-Jun N-terminal kinases. In addition, inhibition of protein phosphatase 1/2A or calcineurin increased GluR1-Ser831 phosphorylation in the dorsal striatum of normal rats, whereas inhibition of these phosphatases did not further enhance the Ser831 phosphorylation in rats pretreated with 7 daily injections of cocaine. These data suggest that the phosphorylation of AMPA receptor GluR1 subunits at Ser831 is subject to upregulation by acute and repeated cocaine administration. Complex signaling integrations among glutamate receptors, Ca(2+) channels, protein kinases, and protein phosphatases participate in this upregulation.

Yeast thiol-dependent protector protein expression enhances the resistance of Escherichia coli to hydrogen peroxide

A soluble protein from Saccharomyces cerevisiae specifically provides protection against a thiol-containing oxidation system but not against an oxidation system without thiol. This 25-kDa protein was thus named thiol-dependent protector protein (TPP). The role of TPP in the cellular defense against oxidative stress was investigated in Escherichia coli containing an expression vector with a yeast genomic DNA fragment that encodes TPP (strain YP) and mutants in which the catalytically essential amino acid cysteine (Cys-47) has been replaced with alanine (strain YPC47A) or tryptophan (Trp-82) has been replaced with phenylalanine (strain YPW82F) by a site directed mutagenesis. There was a distinct difference between these three strains in regards to growth inhibition kinetics, viability, modulation of activities of superoxide dismutase and catalase, and the accumulation of oxidized proteins. These results suggest that TPP may play a direct role in the cellular defense against oxidative stress by functioning as an antioxidant protein.

Translocation of recombinant p47phox cytosolic component of the phagocyte oxidase by in vitro phosphorylation

Activation of superoxide-generating NADPH oxidase system of human neutrophils involves phosphorylation-dependent translocation of p47phox and other cytosolic components to the plasma membrane. In contrast to the stimulation of the NADPH oxidase in intact cells, however, the activation of cell-free system requires the addition of anionic amphiphiles such as sodium dodecyl sulfate (SDS) and arachidonate. In this system, translocation of p47phox is also an essential step for activation, but phosphorylation is not required. The basis of this difference in oxidase activation is not yet clear. We now report that in a cell-free oxidase system, phosphorylated recombinant p47phox can be translocated to the membrane in the absence of SDS or arachidonate. These findings suggest that both phosphorylation and SDS could cause a common change in conformation or charge of p47phox that may result in the association of p47phox with the plasma membrane.

A computer algorithm for spatio-temporal patterns in interactive neuron populations

A computer algorithm has been developed which enables numerical computations to be performed for interactive neuron populations whose spatio-temporal behaviors are represented by a set of certain integro-differential equations. The computation is based on the fact that the eigenfunctions of a symmetric Hilbert-Schmidt operator form a set of complete orthonormal functions in L2 space. This algorithm differs from the ones which computes the value of the solution at each (x,t) point in that it computes the coefficients corresponding to the eigenfunctions. Therefore it is shown that the error in the coefficient of one eigenfunction does not propagate to that of another eigenfunction from one sampling time to the next one. This enables us to analyze the temporal behavior of one spatial frequency which is not affected by that of the other spatial frequencies.