Birgitta Schmidt

Lipid mediator class switching during acute inflammation: signals in resolution

Leukotrienes (LTs) and prostaglandins (PGs) amplify acute inflammation, whereas lipoxins (LXs) have unique anti-inflammatory actions. Temporal analyses of these eicosanoids in clinical and experimental exudates showed early coordinate appearance of LT and PG with polymorphonuclear neutrophil (PMN) recruitment. This was followed by LX biosynthesis, which was concurrent with spontaneous resolution. Human peripheral blood PMNs exposed to PGE2 (as in exudates) switched eicosanoid biosynthesis from predominantly LTB4 and 5-lipoxygenase (5-LO)–initiated pathways to LXA4, a 15-LO product that “stopped” PMN infiltration. These results indicate that first-phase eicosanoids promote a shift to anti-inflammatory lipids: functionally distinct lipid-mediator profiles switch during acute exudate formation to “reprogram” the exudate PMNs to promote resolution.

Multi-pronged inhibition of airway hyper-responsiveness and inflammation by lipoxin A 4

The prevalence of asthma continues to increase and its optimal treatment remains a challenge. Here, we investigated the actions of lipoxin A4 (LXA4) and its leukocyte receptor in pulmonary inflammation using a murine model of asthma. Allergen challenge initiated airway biosynthesis of LXA4 and increased expression of its receptor. Administration of a stable analog of LXA4 blocked both airway hyper-responsiveness and pulmonary inflammation, as shown by decreased leukocytes and mediators, including interleukin-5, interleukin-13, eotaxin, prostanoids and cysteinyl leukotrienes. Moreover, transgenic expression of human LXA4 receptors in murine leukocytes led to significant inhibition of pulmonary inflammation and eicosanoid-initiated eosinophil tissue infiltration. Inhibition of airway hyper-responsiveness and allergic airway inflammation with a stable LXA4 analog highlights a unique counter-regulatory profile for the LXA4 system and its leukocyte receptor in airway responses. Moreover, our findings suggest that lipoxin and related pathways offer novel multi-pronged therapeutic approaches for human asthma.

Infection regulates pro-resolving mediators that lower antibiotic requirements.

Underlying mechanisms for how bacterial infections contribute to active resolution of acute inflammation are unknown. Here, we performed exudate leukocyte trafficking and mediator-metabololipidomics of murine peritoneal Escherichia coli infections with temporal identification of pro-inflammatory (prostaglandins and leukotrienes) and specialized pro-resolving mediators (SPMs). In self-resolving E. coli exudates (105 colony forming units, c.f.u.), the dominant SPMs identified were resolvin (Rv) D5 and protectin D1 (PD1), which at 12 h were at significantly greater levels than in exudates from higher titre E. coli (107 c.f.u.)-challenged mice. Germ-free mice had endogenous RvD1 and PD1 levels higher than in conventional mice. RvD1 and RvD5 (nanograms per mouse) each reduced bacterial titres in blood and exudates, E. coli-induced hypothermia and increased survival, demonstrating the first actions of RvD5. With human polymorphonuclear neutrophils and macrophages, RvD1, RvD5 and PD1 each directly enhanced phagocytosis of E. coli, and RvD5 counter-regulated a panel of pro-inflammatory genes, including NF-κB and TNF-α. RvD5 activated the RvD1 receptor, GPR32, to enhance phagocytosis. With self-limited E. coli infections, RvD1 and the antibiotic ciprofloxacin accelerated resolution, each shortening resolution intervals (Ri). Host-directed RvD1 actions enhanced ciprofloxacin’s therapeutic actions. In 107 c.f.u. E. coli infections, SPMs (RvD1, RvD5, PD1) together with ciprofloxacin also heightened host antimicrobial responses. In skin infections, SPMs enhanced vancomycin clearance of Staphylococcus aureus. These results demonstrate that specific SPMs are temporally and differentially regulated during infections and that they are anti-phlogistic, enhance containment and lower antibiotic requirements for bacterial clearance.

Lipoxins and novel 15-epi-lipoxin analogs display potent anti-inflammatory actions after oral administration

Lipoxins (LX) and aspirin‐triggered 15‐epi‐lipoxins (ATL) exert potent anti‐inflammatory actions. In the present study, we determined the anti‐inflammatory efficacy of endogenous LXA4 and LXB4, the stable ATL analog ATLa2, and a series of novel 3‐oxa‐ATL analogs (ZK‐996, ZK‐990, ZK‐994, and ZK‐142) after intravenous, oral, and topical administration in mice. LXA4, LXB4, ATLa2, and ZK‐994 were orally active, exhibiting potent systemic inhibition of zymosan A‐induced peritonitis at very low doses (50 ng kg−1–50 μg kg−1). Intravenous ZK‐994 and ZK‐142 (500 μg kg−1) potently attenuated hind limb ischemia/reperfusion‐induced lung injury, with 32±12 and 53±5% inhibition (P<0.05), respectively, of neutrophil accumulation in lungs. The same dose of ATLa2 had no significant protective action. Topical application of ATLa2, ZK‐994, and ZK‐142 (∼20 μg cm−2) prevented vascular leakage and neutrophil infiltration in LTB4/PGE2‐stimulated ear skin inflammation. While ATLa2 and ZK‐142 displayed approximately equal anti‐inflammatory efficacy in this model, ZK‐994 displayed a slower onset of action. In summary, native LXA4 and LXB4, and analogs ATLa2, ZK‐142, and ZK‐994 retain broad anti‐inflammatory effects after intravenous, oral, and topical administration. The 3‐oxa‐ATL analogs, which have enhanced metabolic and chemical stability and a superior pharmacokinetic profile, provide new opportunities to explore the actions and therapeutic potential for LX and ATL.

Atypical genital nevi. A clinicopathologic analysis of 56 cases

Atypical genital nevi are rare melanocytic lesions that most commonly arise on the vulva of young women. They are currently regarded as nevi of special sites, in that despite histologically worrisome features, their clinical behavior is reportedly benign. However, only few studies with limited follow-up data are available. To better characterize the clinical presentation and behavior of these lesions and to further delineate their histologic features, we retrieved 56 atypical genital nevi arising in the lower female genital tract from our departmental and consultation files. The 56 lesions arose in 55 female patients with a median age of 26 years (range, 6 to 54 y). The dominant histologic feature was a lentiginous and nested junctional component composed of prominent round or fusiform nests, which often showed retraction artifact and/or cellular dyscohesion. Cytologic atypia was mild in 11 cases (20%), moderate in 34 (60%), and severe in 11 (20%). Ten cases (18%) showed focal pagetoid spread, with extension to the granular layer and stratum corneum in 1 case. The atypical junctional melanocytic proliferation was associated with a large common dermal nevus component that dominated the lesion in 26 cases (46%). Adnexal spread (46%) and nuclear atypia of melanocytes situated in the superficial dermis (39%) were relatively common, but dermal mitoses (7%) were uncommon and maturation was present in all cases. A broad zone of dense eosinophilic fibrosis within the superficial dermis was a frequent finding (41%). Clinical follow-up was available in 45 cases (80%) with a median follow-up period of 3.5 years (range, 1 to 16 y). Only 1 lesion recurred, 1.5 years after the initial excision. The original nevus in this patient had only mild cytologic atypia and was present at the margins of excision. The recurrent/persistent nevus was reexcised, and there was no further clinical recurrence in 11.5 additional years of follow-up. Our data support the hypothesis that atypical genital nevi have a benign clinical course despite their occasionally striking cytologic and architectural atypia. Awareness and recognition of this group of melanocytic lesions is important to avoid over diagnosis as melanoma with subsequent wide excision and possibly sentinel lymph node biopsy.

Dysplastic naevi with moderate to severe histological dysplasia : a risk factor for melanoma

Background  The risk of malignant melanoma associated with histologically dysplastic naevi (HDN) has not been defined. While clinically atypical naevi appear to confer an independent risk of melanoma, no study has evaluated the extent to which HDN are predictive of melanoma.

Management of Nevus Sebaceous and the Risk of Basal Cell Carcinoma: An 18‐Year Review

Abstract:  Nevus sebaceous (NS) is a common congenital hamartoma of the skin, usually found on the head and neck. It may undergo malignant transformation to basal cell carcinoma (BCC). However the incidence and lifetime risk of malignant transformation is unknown. We performed an 18‐year review of all NS excisions at our institution, to report the number of cases of BCC and other neoplasms within excised NS. The aim is to inform physicians who must weigh the risks in recommending excision of a NS in a pediatric patient population with the risk of malignancy. After a database query for years 1990–2008, charts were reviewed and data were extracted on demographics and surgical history relating to NS. Thirty‐one NS with abnormal findings were reviewed microscopically by a dermatopathologist. There were 651 NS distinct lesions among 631 patients and 690 excisions. Twenty‐one intralesional diagnoses were found in 18 patients. Five patients (0.8%) had BCC (mean age 12.5 yrs, range 9.7–17.4 yrs). Seven (1.1%) had syringocystadenoma papilliferum (SP) (mean age 8.8 yrs, range 1.7–16.9 yrs), a lesion that may undergo malignant transformation. Malignant transformation of NS can occur in childhood or adolescence. We believe all NS should be excised, however timing of excision can be flexible. Our data do not support age cutoffs or morphologic changes to determine optimal excision time. In conjunction with the treating physician, the parent and patient may weigh the small risk of malignant transformation of NS against the morbidity associated with excision and anesthesia.

A synthetic eicosanoid LX-mimetic unravels host-donor interactions in allogeneic BMT-induced GvHD to reveal an early protective role for host neutrophils

Lipoxin A4 (LXA4) and aspirin‐triggered 15‐epi‐LXA4 are potent endogenous lipid mediators thought to define the inflammatory set‐point. We used single prophylactic administrations of a synthetic aspirin‐triggered lipoxin A4 signal mimetic, ATLa, to probe dynamics of early host‐donor interactions in a mouse model for the inflammation‐associated multifactorial disease of allogeneic bone marrow transplant (BMT) ‐induced graft‐vs.‐host disease (GvHD). We first demonstrated that both host and donor are responsive to the ATLa signals. The simple and restricted regimen of a single prophylactic administration of ATLa [100 ng/mL to donor cells or 1 µg(∼50 µg/kg) i.v. to host] was sufficient to delay death. Clinical indicators of weight, skin lesions, diarrhea and eye inflammation were monitored. Histological analyses on day 45 post‐BMT showed that the degree of cellular trafficking, particularly neutrophil infiltrate, and protection of end‐organ target pathology are different, depending on whether the host or donor was treated with ATLa. Taken together, these results chart some ATLa protective effects on GvHD cellular dynamics over time and identify a previously unrecognized effect of host neutrophils in the early phase post‐BMT as important determinants in the dynamics of GvHD onset and progression.—DevchandP. R., SchmidtB. A., PrimoV. C., ZhangQ.‐Y., ArnaoutM. A., SerhanC. N., NikolicB. A synthetic eicosanoid LX‐mimetic unravels host‐donor interactions in allogeneic BMT‐induced GvHD to reveal an early protective role for host neutrophils. FASEB J. 19, 203–210 (2005)

Outcomes in pediatric atypical spitz tumors treated without sentinel lymph node biopsy.

Abstract:  The diagnosis of atypical Spitz tumor (AST) in a pediatric patient conveys an uncertain potential for malignancy. Although pediatric melanoma is rare, AST may be treated aggressively with sentinel lymph node biopsy (SLNB) and subsequent completion lymphadenectomy. These procedures have unclear therapeutic benefit and potential morbidity. We aimed to collect outcomes on children with AST treated with excision alone to assist in the management of these lesions. We queried our institution’s pathology database for AST specimens submitted between 1994 and 2009. A dermatopathologist reviewed pathology slides to confirm AST diagnosis. Clinical information was obtained from medical records, and outcomes surveys were administered to children with AST. Twenty‐nine patients met AST diagnostic criteria and were included in this study. Mean age at first excision was 9.0 ± 4.2 (range 2.3–17.5), and 19 patients underwent more than one excision procedure to achieve clear margins. No patient had SLNB. Fourteen patients (48%) with mean follow‐up time of 8.4 years (range 3.5–15.8) completed clinical outcomes surveys. Outcomes with mean follow‐up time of 2.8 years (range 0.02–8.1 years) were obtained for 10 additional patients from medical records. There were no reports of recurrence, additional lesions, or metastases in these 24 patients. We report one of the largest series of children with AST treated using excision alone and who remain disease free after a significant follow‐up period. Our data suggest that SLNB is not warranted in the routine management of pediatric AST. We recommend complete excision with clear margins and careful clinical follow‐up.

Resolvins suppress tumor growth and enhance cancer therapy.

Cancer therapy reduces tumor burden by killing tumor cells, yet it simultaneously creates tumor cell debris that may stimulate inflammation and tumor growth. Thus, conventional cancer therapy is inherently a double-edged sword. In this study, we show that tumor cells killed by chemotherapy or targeted therapy (“tumor cell debris”) stimulate primary tumor growth when coinjected with a subthreshold (nontumorigenic) inoculum of tumor cells by triggering macrophage proinflammatory cytokine release after phosphatidylserine exposure. Debris-stimulated tumors were inhibited by antiinflammatory and proresolving lipid autacoids, namely resolvin D1 (RvD1), RvD2, or RvE1. These mediators specifically inhibit debris-stimulated cancer progression by enhancing clearance of debris via macrophage phagocytosis in multiple tumor types. Resolvins counterregulate the release of cytokines/chemokines, including TNF&agr;, IL-6, IL-8, CCL4, and CCL5, by human macrophages stimulated with cell debris. These results demonstrate that enhancing endogenous clearance of tumor cell debris is a new therapeutic target that may complement cytotoxic cancer therapies.