NLRP3 protects mice from radiation-induced colon and skin damage via attenuating cGAS-STING signaling.

In the present study, the effects of NLRP3 on radiation-induced tissue damage, including colon and skin damage in mice, and the possible mechanisms were explored in vivo and in vitro. The mice were subjected to whole abdomen radiation by timed exposure to X-ray at a cumulative dose of 14 Gy. The survival rate showed that NLRP3 deficiency increased the mortality rate in mice. Furthermore, colon damage, evaluated by H&E staining and barrier function analysis, were significantly aggravated by NLRP3 deficiency. Enhanced phosphorylation of p-TBK1 and p-IRF3 in colonic tissue as well as elevated IFN-ß levels in the serum indicated hyperactivation of cGAS-STING signaling. Moreover, radiation-induced expression of p-TBK1, p-IRF3, and IFN-ß in BMDMs increased in vitro after NLRP3 knockout. Thus, our study outcomes suggest that NLRP3 may protect mice from radiation-induced tissue damage via attenuating cGAS-STING signaling.

Poly-ADP-ribose polymerase inhibition enhances ischemic and diabetic wound healing by promoting angiogenesis.

OBJECTIVE: Chronic nonhealing wounds are a major health problem for patients in the United States and worldwide. Diabetes and ischemia are two major risk factors behind impaired healing of chronic lower extremity wounds. Poly-ADP-ribose polymerase (PARP) is found to be overactivated with both ischemic and diabetic conditions. This study seeks a better understanding of the role of PARP in ischemic and diabetic wound healing, with a specific focus on angiogenesis and vasculogenesis. METHODS: Ischemic and diabetic wounds were created in FVB/NJ mice and an in vitro scratch wound model. PARP inhibitor PJ34 was delivered to the animals at 10 mg/kg/d through implanted osmotic pumps or added to the culture medium, respectively. Animal wound healing was assessed by daily digital photographs. Animal wound tissues, peripheral blood, and bone marrow cells were collected at different time points for further analysis with Western blot and flow cytometry. Scratch wound migration and invasion angiogenesis assays were performed using human umbilical vein endothelial cells (HUVECs). Measurements were reported as mean ± standard deviation. Continuous measurements were compared by t-test. P < .05 was considered statistically significant. RESULTS: A significant increase in PARP activity was observed under ischemic and diabetic conditions that correlated with delayed wound healing and slower HUVEC migration. The beneficial effect of PARP inhibition with PJ34 on ischemic and diabetic wound healing was observed in both animal and in vitro models. In the animal model, the percentage of wound healing was significantly enhanced from 43% ± 6% to 71% ± 9% (P < .05) by day 7 with the addition of PJ34. PARP inhibition promoted angiogenesis at the ischemic and diabetic wound beds as evidenced by significantly higher levels of endothelial cell markers (vascular endothelial growth factor receptor 2 [VEGFR2] and endothelial nitric oxide synthase) in mice treated with PJ34 compared with controls. Flow cytometry analysis of peripheral blood mononuclear cells showed that PARP inhibition increased mobilization of endothelial progenitor cells (VEGFR2+/CD133+ and VEGFR2+/CD34+) into the systemic circulation. Furthermore, under in vitro hyperglycemia and hypoxia conditions, PARP inhibition enhanced HUVEC migration and invasion in Boyden chamber assays by 80% and 180% (P < .05), respectively. CONCLUSIONS: Delayed healing in ischemic and diabetic wounds is caused by PARP hyperactivity, and PARP inhibition significantly enhanced ischemic and diabetic wound healing by promoting angiogenesis.

Protein tyrosine phosphatase 1B impairs diabetic wound healing through vascular endothelial growth factor receptor 2 dephosphorylation.

OBJECTIVE: Impaired wound healing is a major complication of diabetes mellitus. The mechanisms that govern wound healing, however, are complex and incompletely understood. In the present study, we determined the inhibitory role of protein tyrosine phosphatase 1B (PTP1B) in the process of diabetic wound healing. APPROACH AND RESULTS: First, by comparing the wound healing process in PTP1B knockout (PTP1B(-/-)) mice, ob/ob mice and their wild-type littermates in the presence or absence of streptozotocin treatment, we showed that the inhibition of mouse wound healing in streptozotocin-induced diabetic conditions is because of the upregulation and activation of PTP1B. Second, the impaired wound healing in ob/ob mice and streptozotocin-treated wild-type mice was rescued by a PTP1B inhibitor. Third, PTP1B, which is upregulated under hyperglycemic condition, inhibited the tube formation, proliferation, and migration of human microvascular endothelial cells induced by vascular endothelial growth factor, whereas this inhibition was largely abolished by the PTP1B inhibitor. Finally, mechanism study further indicated that PTP1B likely suppressed the proliferation, migration, and tube formation of vascular endothelial cells through dephosphorylation of vascular endothelial growth factor receptor 2. CONCLUSIONS: Our study demonstrated that PTP1B negatively modulated the diabetic wound healing process by dephosphorylating the endothelial cell vascular endothelial growth factor receptor 2 and that the specific inhibitor of PTP1B might serve as a potential novel therapeutic tool for diabetic wound healing.

Tofacitinib Treatment of Refractory Cutaneous Leukocytoclastic Vasculitis: A Case Report.

Introduction: To date, there is no treatment with proven efficacy for cutaneous leukocytoclastic vasculitis (CLV). Several reports have suggested that CLV responds favorably to corticosteroids, colchicine, nonsteroidal anti-inflammatory drugs (NSAIDs), azathioprine, and hydroxychloroquine (HCQ). To the best of our knowledge, the oral small molecule Janus kinase inhibitor, tofacitinib, plays an important role in the treatment of autoimmune and inflammatory diseases. Therefore, tofacitinib may be a prospective therapy in patients with CLV. Case Presentation: A 29-year-old woman presented to our hospital with a 5-year history of symmetric skin lesions mainly affecting both lower extremities. The results for anti-neutrophil cytoplasmic antibodies (ANCA), anti-extracted nuclear antigens (ENA) autoantibodies, anti-double-stranded deoxyribonucleic acid (dsDNA) antibodies, and antinuclear antibodies (ANA) were all negative. The definite diagnosis of CLV was determined by a skin biopsy. However, the patient exhibited a poor response to prednisone, HCQ, methotrexate, colchicine, azathioprine, and tripterygium wilfordii polyglycoside tablets (TGTs) treatments. She was then treated with oral tofacitinib (5 mg twice daily) and oral prednisone (25 mg daily). Outcomes: Her skin lesions gradually improved over a period of 4 weeks. Two months later, the skin ulcers completely resolved. No evidence of recurrence of skin ulcers was observed during a 6-month follow-up. Conclusion: We present the first case of a female patient receiving short-term tofacitinib therapy for refractory CLV. Tofacitinib may be a promising oral alternative for patients with CLV. However, its efficacy and safety require further appraisal through clinical trials.

Despite antiatherogenic metabolic characteristics, SCD1-deficient mice have increased inflammation and atherosclerosis.

OBJECTIVE: Absence of stearoyl-CoA desaturase-1 (SCD1) in mice reduces plasma triglycerides and provides protection from obesity and insulin resistance, which would be predicted to be associated with reduced susceptibility to atherosclerosis. The aim of this study was to determine the effect of SCD1 deficiency on atherosclerosis. METHODS AND RESULTS: Despite an antiatherogenic metabolic profile, SCD1 deficiency increases atherosclerosis in hyperlipidemic low-density lipoprotein receptor (LDLR)-deficient mice challenged with a Western diet. Lesion area at the aortic root is significantly increased in males and females in two models of SCD1 deficiency. Inflammatory changes are evident in the skin of these mice, including increased intercellular adhesion molecule (ICAM)-1 and ulcerative dermatitis. Increases in ICAM-1 and interleukin-6 are also evident in plasma of SCD1-deficient mice. HDL particles demonstrate changes associated with inflammation, including decreased plasma apoA-II and apoA-I and paraoxonase-1 and increased plasma serum amyloid A. Lipopolysaccharide-induced inflammatory response and cholesterol efflux are not altered in SCD1-deficient macrophages. In addition, when SCD1 deficiency is limited to bone marrow-derived cells, lesion size is not altered in LDLR-deficient mice. CONCLUSIONS: These studies reinforce the crucial role of chronic inflammation in promoting atherosclerosis, even in the presence of antiatherogenic biochemical and metabolic characteristics.

Clinical and biochemical characteristics of prolidase deficiency in siblings.

Two brothers with recurrent skin ulcers of the lower limbs, subnormal intelligence, developmental abnormalities, and poliosis were found to excrete large quantities of several imidodipeptides in their urine. Glycylproline was the most prominent imidodipeptide excreted and was also detected in their blood. Prolidase activity was markedly deficient in red blood cells from both patients (4.1% and 3.7% of control mean) and skin fibroblasts from the one brother so examined (3.7% of control mean). A total of 20 patients with prolidase deficiency, including the two in this report, have been described in the literature. Their manifestations and various attempts at treatment are reviewed.

Patterns of matrix metalloproteinase and TIMP expression in chronic ulcers.

Controlled proteolysis is needed for cell migration, angiogenesis, and matrix remodeling during normal wound repair. Our objective has been to investigate how chronic leg ulcers differ from normally healing wounds (pinch graft donor sites) with respect to their metalloproteinase expression patterns. Using in situ hybridization and immunohistochemistry, we found that collagenase-1 (MMP-1), stromelysin-1 (MMP-3) and stromelysin-2 (MMP-10) were expressed in keratinocytes bordering both acute and chronic wounds. Unlike MMP-1, signal for collagenase-3 (MMP-13) was not detected in keratinocytes but exclusively in fibroblasts deep in the ulcer bed of chronic wounds, suggesting that while MMP-1 production is important for migration, MMP-13 plays a role in matrix remodeling. Tissue inhibitor of metalloproteinase (TIMP)-1 was not detected in the epidermis of any chronic wound sample while it was expressed in keratinocytes bordering normally healing wounds. TIMP-3 was abundantly expressed in stromal fibroblast- and macrophage-like cells surrounding vessels and sweat glands in both types of wounds. Our results suggest that there are no qualitative differences in the expression of MMPs-1, -3 and -10 in the epidermis of chronic vs normally healing wounds. However, the number of stromal cells expressing MMP-1 and MMP-3 was greater in chronic vs acute wounds, whereas MMP-10 was never detected in the dermis. TIMP-1 expression near the basement membrane in acute, but not in chronic, wounds suggests that the balance between MMPs and their inhibitors may be altered in poorly healing wounds. Analogous to chronic cutaneous wounds, MMP-1 and -3 are abundantly expressed in chronic small and large bowel ulcers, while the migrating surface epithelium is negative for TIMP-1 expression.

Expression of telomerase reverse transcriptase in radiation-induced chronic human skin ulcer.

The objective of this study was to investigate the expression of the catalytic subunit of telomerase, telomerase reverse transcriptase (TRT), and the possible relationship between the TRT expression and poor healing or cancer transformation in radiation-induced chronic human skin ulcer. Rabbit antibody to human TRT and SP immunohistochemical method were used to detect TRT expression in 24 cases of formalin-fixed, paraffin-embedded chronic human skin ulcer tissues induced by radiation, 5 cases of normal skin, 2 of burned skin, and 8 of cancer. The positive rate of TRT expression in chronic radiation ulcers was 58.3% (14/24), of which it was strongly positive in 41.7% cases (10/24) and weakly positive in 16.7% (4/24). TRT expression was 0% in normal (0/5) and burned skin (0/2), and 100% in cancer cases (8/8). The strongly positive expression of TRT was observed almost always in the cytoplasm and nucleus of squamous epithelial cells of the epidermis but it was negative or only weakly positive in the smooth muscle and endothelia of small blood vessels and capillaries, and in fibroblasts. Chronic inflammatory cells, plasmacytes, and lymphocytes were weakly positive for TRT. TRT expression could be involved in the poor healing caused by sclerosis of small blood vessels and lack of granulation tissue and in the cancer transformation of chronic radiation ulcer.

Telomerase activity in radiation-induced chronic human skin ulcers.

An increasing activity of telomerase is considered to be a reliable molecular biological marker for malignancy. There is much research work on telomerase detection in malignant tumors, but no such investigation was carried out in chronic skin ulcers induced by radiation. We investigated the levels of telomerase activity in radiation-induced chronic human skin ulcers and the possible relationship between the enzyme and cancer transformation. We used the nonisotopic telomere repeat amplification protocol (TRAP) in 20 cases of chronic human skin ulcers induced by radiation, 5 cases of normal skin, 2 of burned skin, and 5 of carcinoma. Our results showed that the positive rate for telomerase activity was 30% in chronic radiation skin ulcers, 0% in normal and burned skin, and 100% in carcinoma. The telomerase activity in radiation ulcers was weaker than that detected in carcinoma. We suggest that the telomerase activity assay could be used as a marker for predicting the prognosis and the effect of treatment in chronic human skin ulcers induced by radiation.

Corticosteroid treatment of prolidase deficiency skin lesions by inhibiting iminodipeptide-primed neutrophil superoxide generation.

We studied the pathogenetic role of iminodipeptides, and the effects of corticosteroids on the skin lesions of two adult female siblings with prolidase deficiency. The elder sister had had severe skin ulcers and mental retardation since childhood, while the younger sister had shown milder clinical manifestations since late adolescence. The ulcers showed vascular wall thickening and neutrophil infiltration. Oral prednisolone at moderate doses was not effective, but corticosteroid pulse therapy followed by a moderate dose of prednisolone improved the preulcerative indurated lesions and ulcers. A 2-year follow-up of the younger patient indicated that N-formyl methionyl leucyl phenylalanine-induced neutrophil superoxide generation was elevated, in parallel with an increase in the serum iminodipeptide level, when the skin ulcers and preulcerative indurated lesions were most active. Corticosteroid pulse therapy downregulated the superoxide generation by neutrophils. The serum iminodipeptide level, however, did not decrease during 25 days after pulse therapy. These findings suggest that iminodipeptides may play an important part in aggravating the skin lesions by priming neutrophil superoxide generation, and that high-dose corticosteroids improve the skin lesions, probably by inhibiting the infiltration, and superoxide generation by, neutrophils. Neutrophil superoxide generation was more prominent in the elder sister, suggesting that clinical severity may depend on the response of neutrophils to the iminodipeptides. Chronic stimulation by superoxide may cause thickening of cerebral blood vessels and eventual mental retardation.

Iminopeptiduria, skin ulcerations, and edema in a boy with prolidase deficiency.

A 12-year-old boy with recurrent skin ulceration, chronic generalized lymphedema, and mild mental retardation was found to excrete massive amounts of dipeptides, most (but not all) of which had proline or hydroxyproline as the carboxyl terminal residue. Glycylproline predominated. Prolidase deficiency was demonstrated in red blood cells and in fibroblastic cells. Prolidase activity was present in continuous lymphoid cell cultures at the same low level observed in control cells.

Inhibitor(s) of prostaglandin biosynthesis and epidermal injury.

Inhibition of the activity of sheep vesicular gland prostaglandin synthetase (a rare limiting enzyme in the biosynthesis of prostaglandins) was demonstrated in the presence of homogenates prepared from skin lesions characterized histologically by epidermal disruption. These inhibitory effects were not observed in homogenates of skin lesions characterized by a lack of epidermal disruption.

[Spontaneous Peripheral Proteolysis/1st Communication: method and results of clinical examinations (author's transl)]. / Spontane periphere Proteolyse. 1. Mitteilung: Methodik und klinische Untersuchungsergebnisse

With a modificated Astrup-fibrin plate-method also an inhibition of proteolysis can be registrated. In various medical areas a spontaneous peripheral proteolysis had been found, especially so in chronical bacterial infections.

Prolidase deficiency: biochemical study of erythrocyte and skin fibroblast prolidase activity in Italian patients.

BACKGROUND AND METHODS: Prolidase deficiency (PD), a rare, autosomally inherited disorder causing iminodipeptiduria is associated with a number of clinical manifestations, the principle feature being chronic skin ulceration. The enzyme prolidase cleaves iminodipeptides containing C-terminal prolyl or hydroxyprolyl residues and is important in the final stages of protein catabolism. We report clinical and biochemical findings in 8 Italian patients with proven prolidase deficiency. There was considerable heterogeneity in age at onset of symptoms (varying from 3-17 years), mental retardation and clinical manifestations (asymptomless to very severe). Prolidase activity was determined in hemolysates of patient erythrocytes and cultured dermal fibroblasts. RESULTS: Prolidase activity was found to be deficient, especially against gly-pro. Erythrocyte and fibroblast enzyme was also separated into two forms, a major isoform (I) and a minor one (II) by fast protein liquid chromatography, and activity against different iminodipeptide substrates was tested. Isoform I activity was markedly reduced in all patients as compared to normal controls, while isoform II activity appeared to be unaltered. CONCLUSIONS: We were unable to find any correlation between degree of enzyme activity loss and severity of symptoms.

Skin-specific caspase-1-transgenic mice show cutaneous apoptosis and pre-endotoxin shock condition with a high serum level of IL-18.

To study the pathophysiological roles of overexpressed caspase-1 (CASP1), originally designated as IL-1 beta-converting enzyme, we generated transgenic mice in which human CASP1 is overexpressed in their keratinocytes. The transgenic mice spontaneously developed recalcitrant dermatitis and skin ulcers, characterized by the presence of massive keratinocyte apoptosis. The skin of the mice contained the active form of human CASP1 and expressed mRNA for caspase-activated DNase, an effector endonuclease responsible for DNA fragmentation. Their skin and sera showed elevated levels of mature IL-18 and IL-1 beta, but not of IFN-gamma. The plasma from these animals induced IFN-gamma production by IL-18-responsive NK cells. Administration of heat-killed Propionibacterium acnes, a potent in vivo type 1 cell inducer, caused IFN-gamma-mediated lethal liver injury in the transgenic mice, which was completely inhibited by treatment with neutralizing anti-IL-18 Ab. These results indicated that in vivo overexpression of CASP1 caused spontaneous apoptotic tissue injury and rendered mice highly susceptible to exogenous type 1 cell-inducing condition in collaboration with endogenously accumulated proinflammatory cytokines.