Gastric inflammatory myofibroblastic tumor presented with severe anemia and inflammation: a case report.

BACKGROUND: Inflammatory myofibroblastic tumor (IMT) is a rare stromal tumor, often found in children and young adults, and most commonly occurs in the lungs. Surgical resection is considered the standard treatment for localized IMT, although only limited data exist. Gastric IMT in adults is extremely rare, and there are no established guidelines for its treatment. CASE PRESENTATION: A 69-year-old male presented with persistent fatigue and weakness. Laboratory examination revealed severe anemia and inflammation. Upper gastrointestinal endoscopy at admission revealed a 40-mm type I softish tumor in the lesser curvature of the gastric body, without apparent hemorrhage. Repeated biopsies, including partial resection with snare, failed to give a definitive diagnosis. Computed tomography (CT) revealed a massive lesion at the gastric body, protruding into the gastric lumen, which was consistent with the gastric tumor. After admission, the patient developed anemia refractory to frequent blood transfusions despite the absence of apparent gastrointestinal bleeding. In addition, the patient had recurrent fevers of 38 °C or higher, and persistent high inflammatory levels. Fluorodeoxyglucose-positron emission tomography (FDG-PET) CT 1 month after the first visit exhibited an increased FDG uptake in the gastric tumor. In addition, this CT scan revealed a rapid increase in tumor size to 75 mm. It was suspected that the undiagnosed gastric tumor caused these serious clinical symptoms, and he underwent distal gastrectomy and cholecystectomy. The gross image of the tumor showed an 80-mm cauliflower-like shape with a gelatinous texture. The histopathological diagnosis was IMT. The postoperative course was uneventful, and the patient's symptoms subsided drastically, improving both anemia and systemic inflammation. The patient has shown no recurrence or relapse of the symptoms over one and a half years. CONCLUSIONS: In this case, the tumor resection finally enabled the diagnosis of IMT and resolved the clinical symptoms. Despite its predominantly benign morphological nature, some cases of IMT present clinically adverse courses. Surgical treatment may lead to its final diagnosis and improvement of clinical symptoms.

Reduced Rate of Disease Flares in Japanese Patients with Systemic Lupus Erythematosus: An Altered Balance between the Use of Glucocorticoids and Immunosuppressants in Recent Decades.

Objective This study examined whether or not the disease control in Japanese patients with systemic lupus erythematosus (SLE) had improved in recent years and its possible association with altered balance between the use of glucocorticoids and immunosuppressants. Methods We enrolled Japanese patients with SLE who visited our medical center during 2013-2017 (Group A, 75 patients) and compared them with patients encountered during 1999-2003 (Group B, 69 patients; not overlapping with Group A). Patient background characteristics, doses of glucocorticoids, and the use of immunosuppressants at the times of SLE onset and disease flares were reviewed from the medical records. Disease flare was defined as new British Isles Lupus Assessment Group 2004 A or B scores in at least one system. Results Lupus nephritis and neuropsychiatric manifestations were less frequently observed in Group A than in Group B (p=0.042 and p=0.045, respectively). Although the initial glucocorticoid dosage was similar between the groups, the inclusion rate of immunosuppressants in the initial SLE treatment was significantly higher in Group A than in Group B (56% vs. 6% in Group B, p<0.001). The median number of SLE flares per person-year was significantly lower in Group A than in Group B (0 vs. 0.3, respectively, p<0.001), and a propensity score-matched analysis indicated the association of SLE flare with the non-use of immunosuppressants in the initial treatment (p=0.012). The rates of infectious diseases and other complications were similar between the groups. Conclusion The recent aggressive use of immunosuppressants in Japan resulted in a reduction in the rate of SLE flare.

Performance of the Revised Classification Criteria for Systemic Autoimmune Rheumatic Diseases and Their Overlap Syndromes.

Objective We evaluated the performance of the revised classification criteria for assessing different systemic autoimmune rheumatic diseases and their overlap syndromes. Methods A total of 652 patients with or highly suspected of having systemic lupus erythematosus (SLE), systemic sclerosis (SSc), polymyositis (PM)/dermatomyositis (DM) or rheumatoid arthritis (RA) were included in this study. The 1997 revised American College of Rheumatology (ACR) and the 2019 European League Against Rheumatism (EULAR)/ACR criteria for SLE, the 1980 ACR and the 2013 ACR/EULAR criteria for SSc, the criteria by Bohan and Peter and the 2017 EULAR/ACR criteria for PM/DM, and the 1987 revised ACR and 2011 ACR/EULAR criteria for RA were used for disease classification. Results The old and new criteria and a clinical diagnosis were used to respectively classify 103, 106 and 105 SLE patients; 35, 47 and 58 SSc patients; 18, 23 and 33 PM/DM patients; and 297, 389 and 468 RA patients. Sensitivity increased from 82.9% to 92.4% in SLE, from 56.9% to 79.3% in SSc, from 54.5% to 66.7% in PM/DM, and from 62.6% to 80.8% in RA. SLE-SSc was the predominant type of clinical overlap syndrome, while SLE-RA was the most classifiable. Conclusion The revised classification criteria for all the diseases showed an improved sensitivity, and SLE-overlap syndrome was predominant, regardless of the criteria sets.

[Early endoscopic diagnosis can save lives and reduce the extent of colon resection for acute fulminant amebic colitis: a case report with review].

A man in his 50s was referred to the hospital with fever, right lower abdominal pain, and bloody diarrhea. Based on computed tomography images and characteristic varioliform erosions observed during the colonoscopic examination, the patient was diagnosed with fulminant amebic colitis. Intravenous metronidazole was administered immediately. After symptom improvement, a second colonoscopic examination revealed inflammation localized to the right hemicolon. A right colectomy was performed on the 75th hospital day, and the patient was discharged without further problems. Prompt antiamebic therapy based on early endoscopic diagnosis was effective in quelling colonic inflammation in a life-threatening case of acute fulminant amebic colitis. Moreover, colonoscopic reexamination was useful in determining the extent of inflammation and minimizing colon resection.

Clinical characteristics of patients with spondyloarthritis and inflammatory bowel disease versus inflammatory bowel disease-related arthritis.

The purpose of this study was to clarify the clinical characteristics of spondyloarthritis (SpA) patients with inflammatory bowel disease (IBD) compared to those without IBD. Furthermore, among patients with SpA and IBD, we aimed to clarify what clinical characteristics lead rheumatologists to diagnose "IBD-related arthritis." Utilizing SpA and psoriatic arthritis (PsA) patients' data from an international, cross-sectional, observational study, we analyzed information on demographics and disease characteristics, dichotomizing patients by IBD status. The presence or absence of IBD was determined based on data collection of treating rheumatologists. Patients with SpA (including PsA) and IBD were also categorized based on treating rheumatologists' definitive diagnosis in regard to SpA type, and compared by whether the patients had IBD-related arthritis or not. Among 4465 SpA patients, 287 (6.4%, 95%CI 5.7-7.2%) were identified with IBD. Compared to SpA patients without IBD, patients with SpA and IBD had a longer diagnostic delay (5.1 vs. 2.9 years, p < 0.001). In patients with SpA and IBD, 111 (38.7%, 95%CI 33.0-44.6%) were diagnosed with IBD-related arthritis. Multivariable analyses showed that HLA-B27 positivity [OR = 0.35, (95%CI 0.15-0.80)], psoriasis [OR = 0.14, (95%CI 0.04-0.50)], IBD as first symptom of SpA [OR = 3.32, (95%CI 1.84-6.01)], and need for IBD-specific treatment [OR = 5.41, (95%CI 2.02-14.50)] were independently associated with the definitive diagnosis of IBD-related arthritis. Collaboration with gastroenterologists is needed to shorten the diagnostic delay in patients with SpA and IBD. The recognition of the factors for the diagnosis of "IBD-related arthritis" may lead to the elucidation of the pathogenesis.

Prediction of disease flare by biomarkers after discontinuing biologics in patients with rheumatoid arthritis achieving stringent remission.

To elucidate the disease-flare process in rheumatoid arthritis (RA) after discontinuing biological disease-modifying antirheumatic drugs (bDMARDs), we first focused on RA-flare prediction after achieving stringent remission criteria. Patients with RA who maintained a simplified disease activity index ≤ 3.3 for ≥ 3 months during November 2014-January 2018 in our medical centre in Tokyo, Japan, were eligible. The primary endpoint was flare (disease activity score 28-erythrocyte sedimentation rate ≥ 3.2 with increase from baseline > 0.6) within 2 years after bDMARD discontinuation. Comprehensive clinical assessments, ultrasonographic evaluation of 40 joints, and blood sampling for 12 biomarkers were performed every 2-3 months for 2 years unless patients experienced flare. Flare-positive and flare-negative patients were compared using univariate and Kaplan-Meier analyses. Thirty-six patients (80.6% female, median disease duration, 5.2 years; median treatment period with discontinued bDMARD, 2 years; median remission duration, 18 months) were enrolled. Twenty patients (55.6%) experienced RA flare 43-651 (median, 115) days after the first skipped date of bDMARDs. Two patients who withdrew without disease flare were excluded from the comparison. Clinical and ultrasonographic evaluations did not show significant between-group differences; Kaplan-Meier analysis showed that higher baseline soluble tumour necrosis factor receptor 1 (sTNFR1) concentration impacted subsequent disease flare (p = 0.0041); higher baseline interleukin (IL)-2 concentration was exclusively beneficial to patients with lower sTNFR1 (p = 0.0058), resulting in remission maintenance in 83.3% of patients with lower sTNFR1 and higher IL-2. We demonstrated the usefulness of combined biomarker evaluation for predicting sustained remission after bDMARD discontinuation in RA.

Spontaneous regression of mismatch repair-deficient colorectal cancers: Case series.

Spontaneous regression (SR) has been reported in various malignant tumors. However, SR in colorectal cancer (CRC) is particularly rare and the mechanism remains unclear. We here report three cases of CRCs displaying SR, which were experienced at two institutions. Intriguingly, all of these cases displayed the common endoscopic characteristics; superficial elevated lesion accompanied by a central depression (0-IIa + IIc, in the Paris classification), with a nonpolypoid growth, located in the ascending colon. Furthermore, immunohistology of biopsy specimens revealed the lack of DNA mismatch repair proteins within the CRC lesions, suggesting that these were mismatch repair-deficient (dMMR) CRCs. One of the major features of dMMR cancers is an increase in the number of tumor-infiltrating lymphocytes. Thus, the dMMR phenotype might be associated with SR of CRCs through the activation of anti-tumor host immune responses.

Finger Joint Cartilage Evaluated by Semiquantitative Ultrasound Score in Patients With Rheumatoid Arthritis.

OBJECTIVE: Joint destruction in rheumatoid arthritis (RA) includes both bone and cartilage lesions. Since joint space narrowing (JSN) is not a direct evaluation of cartilage using radiography, we aimed to examine the validity of ultrasound (US) cartilage evaluation using a semiquantitative method in patients with RA. METHODS: We enrolled 103 patients with RA who were in remission or showing low disease activity and 42 healthy subjects. The cartilage thickness of the bilateral metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints of the second to fifth fingers was measured by US, and the recorded images were scored semiquantitatively using a scale of 0-2. In addition, the JSN of the corresponding joints was scored using a hand radiograph. The relationships between total cartilage thickness, its semiquantitative score, and JSN score were assessed using Spearman's rank correlation coefficients. RESULTS: Total cartilage thickness was significantly thinner in patients with RA compared to healthy subjects for both the MCP and PIP joints (both P < 0.001). The semiquantitative sum of 16 joints ranged from 2 to 26 (median 8) in patients with RA, which was significantly greater than the 0-11 (median 4) in healthy subjects (P < 0.001). In patients with RA, the semiquantitative score showed a significant negative correlation with cartilage thickness (ρ = -0.64, P < 0.001) and a significant positive correlation with JSN score (ρ = 0.66, P < 0.001). Furthermore, these scores showed a significant correlation with RA disease duration. CONCLUSION: A simplified and direct evaluation of finger joint cartilage damage by semiquantitative US score is valid and useful for patients with RA.

Radical reactions induced by ketoprofen in phospholipid membranes under ultraviolet light irradiation.

2-(3-Benzoylphenyl)propanoic acid (ketoprofen), one of the nonsteroidal anti-inflammatory drugs, causes photocontact dermatitis by ultraviolet (UV) light as a side effect. In this study, we examined radical reactions induced by ketoprofen in the lipid membranes under UV irradiation using egg yolk phosphatidylcholine (egg-PC) liposomal membranes containing 5- or 16-doxyl stearic acid (5- or 16-DSA), which carry nitroxyl radical at the 5- or 16-position of the fatty acid chain, respectively. When the suspension of liposomal membrane was mixed with ketoprofen and irradiated with UV, electron spin resonance signal of 5- and 16-DSA in the membrane decreased. The decay consisted of fast decay and subsequent slow decay. The overall decay for 5-DSA was faster than that for 16-DSA. The rate of slower decay of 16-DSA increased with ketoprofen concentration. The bulk lipid in the membrane affected the rate of slower decay of 5-DSA; the rate increased with the amount of egg-PC and decreased in the rigid membrane composed of dipalmitoylphosphatidylcholine. When spin trapping studies with α-(4-pyridyl 1-oxide)-N-tert-butylnitrone (POBN) and 5,5-dimetyl-1-pyrroline-N-oxide (DMPO) were performed in ketoprofen solution, C-centered radical adducts of POBN and superoxide anion radical adducts of DMPO were detected after UV irradiation. POBN suppressed the signal decay of 5-DSA in the liposomal membrane, whereas superoxide dismutase accelerated it. These results support that ketoprofen penetrates the lipid membrane and induces a radical reaction near the polar region in the membrane, and that ketoprofen-related C-centered radical is involved in the radical reaction.

Association of age with the non-achievement of clinical and functional remission in rheumatoid arthritis.

Patient-reported outcome (PRO) is included in the remission criteria of rheumatoid arthritis (RA). We aimed to determine the effect of age on PRO and the subsequent achievement of clinical and functional RA remission criteria. Three hundred and one patients with non-rheumatic diseases were evaluated using the 0-10 cm visual analog scale (VAS) assessment for musculoskeletal symptoms and a functional health assessment questionnaire-disability index (HAQ-DI). These assessments were compared with those obtained from 149 patients with RA with negative tender/swollen joint counts and normal serum C-reactive levels (objective clinical remission). Of the 301 patients, 32.2%, 26.6%, and 41.2% were classified as non-elderly (< 65 years), early elderly (65-74 years), and late-elderly (≥ 75 years) patients, respectively. VAS > 1 cm and HAQ-DI ≥ 0.5 were observed in 7.3% and 14.5%, respectively, in late-elderly patients, whereas ≤ 1.0% of non-elderly and early elderly patients for the both. Among 149 RA patients in objective remission, however, > 20% and > 10% of early elderly patients (and even non-elderly patients) had VAS > 1 cm and HAQ-DI ≥ 0.5, respectively, and 34.0% and 35.8% of late-elderly patients with RA had VAS > 1 cm and HAQ-DI ≥ 0.5, respectively. Multivariate logistic analysis revealed that age and RA were associated with the non-achievement of VAS ≤ 1 cm and HAQ-DI < 0.5. Therefore, the effect of age, which was independent of the presence of RA even without any objective disease activity, on PRO and the non-achievement of clinical and functional remission criteria was demonstrated.

Macrophages fine-tune pupil shape during development.

Tissue macrophages, which are ubiquitously present innate immune cells, play versatile roles in development and organogenesis. During development, macrophages prune transient or unnecessary synapses in neuronal development, and prune blood vessels in vascular development, facilitating appropriate tissue remodeling. In the present study, we identified that macrophages contributed to the development of pupillary morphology. Csf1op/op mutant mice, in which ocular macrophages are nearly absent, exhibited abnormal pupillary edges, with abnormal protrusions of excess iris tissue into the pupillary space. Macrophages located near the pupillary edge engulfed pigmented debris, which likely consisted of unnecessary iris protrusions that emerge during smoothening of the pupillary edge. Indeed, pupillary edge macrophages phenotypically possessed some features of M2 macrophages, consistent with robust tissue engulfment and remodeling activities. Interestingly, protruding irises in Csf1op/op mice were only detected in gaps between regressing blood vessels. Taken together, our findings uncovered a new role for ocular macrophages, demonstrating that this cell population is important for iris pruning during development.

Development and exacerbation of pulmonary nontuberculous mycobacterial infection in patients with systemic autoimmune rheumatic diseases.

Objectives: To examine the development and exacerbation of pulmonary nontuberculous mycobacterial (NTM) infection in patients with systemic autoimmune rheumatic diseases (SARD).Methods: We conducted a case-control study. Seventeen of 7013 patients with SARD fulfilling the criteria for pulmonary NTM infection were enrolled in the NTM group. The control group was matched for age, sex, and SARD at a ratio of 2:1.Results: Eight patients with rheumatoid arthritis, four with systemic vasculitis, three with Sjögren's syndrome, and one each with dermatomyositis and systemic lupus erythematosus were included in the NTM group. Mycobacterium avium was detected in 12 (71%) patients, M. chelonae in 2, and M. intracellulare, M. abscessus, and M. kansasii in 1 patient each. Preexisting lung disease was more common in the NTM group than in the control group (88% versus 38%, p = .0009), particularly bronchiectasis (65% versus 29%, p = .033). The body mass index and serum albumin level were significantly lower in the NTM group than in the control group. Six patients (35%) experienced NTM exacerbation during observation. Clinical immune status at the time of NTM diagnosis, as indicated by the peripheral blood leukocyte/lymphocyte count and serum immunoglobulin G level, was unremarkable and comparable between patients with and without exacerbation, as were the treatments for SARD.Conclusions: In patients with SARD, pulmonary NTM infection may develop and exacerbate without clinically apparent immunosuppression.

Global assessments of disease activity are age-dependent determinant factors of clinical remission in rheumatoid arthritis.

OBJECTIVE: The aim of the study is to assess the factors associated with clinical remission of patients with rheumatoid arthritis (RA) in daily clinical practice. METHODS: This analysis was based on the data of 304 RA patients in our center between May 2014 and March 2015. The following information was included: tender, swollen, and symptomatic joint counts, patient's and physician's global assessments, functional disability, laboratory and radiographic data, and RA treatments received. RESULTS: The patients were predominantly female (77.6%), with a median age of 71 years and a median disease duration of 5.8 years. Clinical remission rate, determined using the simplified disease activity index (SDAI), was 49.7%. Patient's and physician's global assessments (/10cm) showed a higher score among patients who did not achieve SDAI remission than among those who did (median: 3.2 versus 0.3, p < 0.0001; and median: 1.8 versus 0.3, p < 0.0001, respectively). The contribution of serum C-reactive protein values (mg/dL) to SDAI was limited (median: 0.19 versus 0.06; p < 0.0001), as well as tender or swollen joint counts (median = 0 or 1). On multivariate analysis of factors not directly related to the disease activity, age was an independent risk factor for non-remission, and global assessment scores by patients and physicians showed an age-dependent increase, while counts of tender, swollen and symptomatic joints were comparable among elderly and non-elderly patients. CONCLUSION: Global assessment of disease activity was age-dependent and independent of joint counts, and it provides a critical determinant of clinical non-remission.

Treatment of intermittent hypoxia increases phosphorylated tau in the hippocampus via biological processes common to aging.

Sleep-disordered breathing produces cognitive impairments, and is possibly associated with Alzheimer disease (AD). Intermittent hypoxia treatment (IHT), an experimental model for sleep-disordered breathing, results in cognitive impairments in animals via unknown mechanisms. Here, we exposed mice to IHT protocols, and performed biochemical analyses and microarray analyses regarding their hippocampal samples. In particular, we performed gene ontology (GO)-based microarray analysis to elucidate effects of IHT on hippocampal functioning, which were compared with the effects of various previously-reported experimental conditions on that (ref. Gene Expression Omnibus, The National Center for Biotechnology Information). Our microarray analyses revealed that IHT and aging shared alterations in some common GO, which were also observed with kainic acid treatment, Dicer ablation, or moderate glutamate excess. Mapping the altered genes using the Kyoto Encyclopedia of Genes and Genomes PATHWAY database indicated that IHT and aging affected several pathways including "MAPK signaling pathway", "PI3K-Akt signaling pathway", and "glutamatergic synapse". Consistent with the gene analyses, in vivo analyses revealed that IHT increased phosphorylated tau, reflecting an imbalance of kinases and/or phosphatases, and reduced proteins relevant to glutamatergic synapses. In addition, IHT increased phosphorylated p70 S6 kinase, indicating involvement of the mammalian target of rapamycin signaling pathway. Furthermore, IHT mice demonstrated hyperactivity in Y-maze tests, which was also observed in AD models. We obtained important data or something from the massive amount of microarray data, and confirmed the validity by in vivo analyses: the IHT-induced cognitive impairment may be partially explained by the fact that IHT increases phosphorylated tau via biological processes common to aging. Moreover, as aging is a major risk factor for AD, IHT is a novel model for investigating the pathological processes contributing to AD onset.

Concordance of Patient-Reported Joint Symptoms, Physician-Examined Arthritic Signs, and Ultrasound-Detected Synovitis in Rheumatoid Arthritis.

OBJECTIVE: Ultrasonography has been prevalently used as a valid and objective modality for joint examination in patients with rheumatoid arthritis (RA). This study aimed to examine and compare the concordance between ultrasound, clinical assessment, and patient-reported assessment of joint synovitis in RA. METHODS: Fifty patients with RA (84% female, median age 69 years, median disease duration 31 months, and median Disease Activity Score in 28 joints 3.8) completed the self-evaluation of joint symptoms, including pain and considerable stiffness in the (proximal) interphalangeal, metacarpophalangeal, wrist, elbow, shoulder, knee, and ankle joints. These joints were also examined by a physician in order to assess the presence of tenderness or swelling; the presence of imaging synovitis was assessed by ultrasonography. RESULTS: In a total of 1,492 evaluated joints, symptoms (pain and stiffness), tenderness, and swelling were noted in 288 (19.3%), 182 (12.2%), and 220 (14.7%) joints, respectively, while ultrasound indicated synovitis in 317 (21.2%) joints. Overall concordance with ultrasound findings was lowest for joint tenderness (κ = 0.30), followed by symptoms (κ = 0.39), and by swelling (κ = 0.43), irrespective of the evaluated joint, except for the elbow. Moreover, the percentages of inflamed joints detected only on the basis of symptoms, tenderness, or swelling were 18.6%, 2.2%, and 8.5%, respectively, of all joints with signs of synovitis on ultrasonography. CONCLUSION: Joint swelling showed the best concordance with ultrasonography, followed by patient-reported joint symptoms, and joint tenderness. Joint symptoms, rather than tenderness evaluation, may be a better clinical indicator of synovitis in RA patients.

CCAAT/enhancer binding protein ß is dispensable for development of lung adenocarcinoma.

Lung cancer is the leading cause of cancer death worldwide. Although disruption of normal proliferation and differentiation is a vital component of tumorigenesis, the mechanisms of this process in lung cancer are still unclear. A transcription factor, C/EBPß is a critical regulator of proliferation and/or differentiation in multiple tissues. In lung, C/EBPß is expressed in alveolar pneumocytes and bronchial epithelial cells; however, its roles on normal lung homeostasis and lung cancer development have not been well described. Here we investigated whether C/EBPß is required for normal lung development and whether its aberrant expression and/or activity contribute to lung tumorigenesis. We showed that C/EBPß was expressed in both human normal pneumocytes and lung adenocarcinoma cell lines. We found that overall lung architecture was maintained in Cebpb knockout mice. Neither overexpression of nuclear C/EBPß nor suppression of CEBPB expression had significant effects on cell proliferation. C/EBPß expression and activity remained unchanged upon EGF stimulation. Furthermore, deletion of Cebpb had no impact on lung tumor burden in a lung specific, conditional mutant EGFR lung cancer mouse model. Analyses of data from The Cancer Genome Atlas (TCGA) revealed that expression, promoter methylation, or copy number of CEBPB was not significantly altered in human lung adenocarcinoma. Taken together, our data suggest that C/EBPß is dispensable for development of lung adenocarcinoma.

Ectopic blastema induction by nerve deviation and skin wounding: a new regeneration model in Xenopus laevis.

Recently, the accessory limb model (ALM) has become an alternative study system for limb regeneration studies in axolotls instead of using an amputated limb. ALM progresses limb regeneration study in axolotls because of its advantages. To apply and/or to compare knowledge in axolotl ALM studies to other vertebrates is a conceivable next step. First, Xenopus laevis, an anuran amphibian, was investigated. A Xenopus frog has hypomorphic regeneration ability. Its regeneration ability has been considered intermediate between that of non-regenerative higher vertebrates and regenerative urodele amphibians. Here, we successfully induced an accessory blastema in Xenopus by skin wounding and rerouting of brachial nerve bundles to the wound site, which is the regular ALM surgery. The induced Xenopus ALM blastemas have limited regenerative potential compared with axolotl ALM blastemas. Comparison of ALM blastemas from species with different regenerative potentials may facilitate the identification of the novel expression programs necessary for the formation of cartilage and other tissues during limb regeneration.

Nerve independent limb induction in axolotls.

Urodele amphibians can regenerate their limbs. During limb regeneration, dermal fibroblasts are transformed into undifferentiated cells called blastema cells. These dermis-blastema cells show multipotency. Such so-called endogenous reprogramming of cell differentiation is one of the main targets of amphibian limb regeneration studies. It is well recognized that nerve presence controls the initiation of limb regeneration. Accordingly, nerve factors have been sought in amphibian limb regeneration. To investigate it, a relatively new study system called the accessory limb model (ALM) was developed. Using ALM, two signaling cascades (Fgf and Gdf5 signaling) came under focus. In the present study, Growth and differentiation factor-5 (Gdf5) application to wounded skin initiated limb regeneration responses and resulted in induction of a blastema-like structure in the absence of a nerve. However, the Gdf5-induced structure showed defects as a regeneration blastema, such as absence of detectable Prrx1 expression by in situ hybridization. The defects could be remedied by additional Fibroblasts growth factor (Fgf) inputs. These two inputs (Gdf5 and Fgfs) were sufficient to substitute for the nerve functions in the induction of limb regeneration. Indeed, Fgf2, Fgf8, and Gdf5 applications with the contralateral skin graft resulted in limb formation without nerve supply. Furthermore, acquisition of cartilage differentiation potential of dermal fibroblasts was tested in an in vivo and in vitro combination assay. Dermal fibroblasts cultured with Gdf5 were difficult to participate in cartilage formation when the cultured cells were grafted into cartilage forming region. In contrast, dermal fibroblasts cultured with Fgf2 and Fgf8 became easier to participate into cartilage formation in the same procedure. These results contribute to our understanding of molecular mechanisms of the early phase of amphibian limb regeneration.