Macrophage Polarization during MRONJ Development in Mice.

Macrophages are important regulators of bone remodeling, and M1 polarization is observed in the setting of medication-related osteonecrosis of the jaws (MRONJ). Here, we characterize the phenotype of macrophages during early stages of MRONJ development in zoledronate (ZA)-treated mice with periodontal disease and explore the role of rosiglitazone, a drug that has been reported to lower the M1/M2 macrophage ratio, in MRONJ burden. Mice received ZA, and experimental periodontal disease (EPD) was induced around their second left maxillary molar. The mice were euthanized 1, 2, or 4 wk later. Micro-computed tomography and histologic and immunohistochemical analyses were carried out. In a separate experiment, mice were treated with ZA in the absence or presence of rosiglitazone, EPD was induced for 5 wk, and the MRONJ burden was assessed. An M1 predilection was noted in ZA versus vehicle (Veh) mice at 1, 2, or 4 wk after ligature placement. M1 cells were found to be positive for MMP-13, and their presence coincided with disruption of the surrounding collagen network in ZA mice. Rosiglitazone caused a reversal in the M1/M2 polarization in Veh and ZA mice. Rosiglitazone did not cause significant radiographic changes 5 wk after EPD in Veh or ZA animals. Importantly, percentage osteonecrosis and bone exposure were decreased in the rosiglitazone-treated versus nontreated ZA sites 5 wk after EPD. Our data point to an important role of M1 macrophage polarization with an overexpression of MMP-13 in the early phases of MRONJ development and provide insight into the use of interventional approaches promoting an M2 phenotype as a preventative means to alleviate MRONJ burden.

Nivolumab-induced lichenoid granulomatous stomatitis in a patient with advanced melanoma: A case report.

Lichenoid granulomatous reactions (LGR) are granulomatous inflammations of the skin and oral mucosa, also sharing features of lichenoid lesions. Thus, the present study refers to lichenoid granulomatous dermatitis (LGD) and lichenoid granulomatous stomatitis (LGS). LGR is a condition that can be triggered by drugs, diseases or environmental causes. In the present case study, anti-PD1 (nivolumab) medication had a detrimental effect on the oral mucosa, which clinicaly and histologicaly proved to be LGS. Checkpoint inhibitors consitute a cornerstone in the current treatment of several types of cancer, of which cutaneous melanoma is the best example. Oral lichenoid responses following anti-PD-1 therapy have been recorded in few case reports and small case series. To the best of our knowledhe, this is the first case of LGS being reported as a side effect of immune checkpoint inhibitor treatment.

Antiresorptive-Type and Discontinuation-Timing Affect ONJ Burden.

Osteonecrosis of the jaws (ONJ), a severe side effect of antiresorptive medications, is characterized by exposed, nonhealing bone in the oral cavity. Treatment options for ONJ range from management of symptomology to surgical resection of the affected area. Antiresorptive discontinuation, often termed a "drug holiday," has been used for managing ONJ patients. Antiresorptives can be discontinued prior to oral surgical procedures, such as tooth extraction, to prevent ONJ development or in patients with established ONJ to accelerate healing. Here, our objective was to test these clinical scenarios using the potent bisphosphonate, zoledronic acid (ZA), and the denosumab surrogate for rodents, OPG-Fc, in a rat model of ONJ. Animals were pretreated with antiresorptives or saline, after which we induced ONJ using periapical disease and tooth extraction. In our first experimental design, antiresorptives were discontinued 1 wk prior to tooth extraction, and animals were evaluated 4 wk later for clinical, radiographic, and histologic features of ONJ. In the second experiment, ONJ was established and antiresorptives were discontinued for 4 wk. Discontinuation of OPG-Fc, but not ZA, prior to tooth extraction ameliorated subsequent ONJ development. In contrast, discontinuation of either ZA or OPG-Fc in rats with established ONJ did not lead to ONJ resolution. In conclusion, our findings suggest that antiresorptive discontinuation is dependent on both the type of antiresorptive and the timing of discontinuation.

p38 Expression and Modulation of STAT3 Signaling in Oral Cancer.

p38 protein belongs to Mitogen-activated protein kinases family that link extracellular stimuli with intracellular responses participating in numerous of fundamental cell processes. Persistent activation of STAT3 has been associated with cell proliferation, differentiation and apoptosis in oral squamous cell carcinoma (OSCC). This study examines the effects of p38 modulation on STAT3 signaling and cellular activities in OSCC cells and investigates possible correlation of p38 expression with tumor degree of differentiation. Phospho-p38 immunostaining was performed in 60 OSCC including well, moderately and poorly differentiated tumors. Semiquantitative analysis was used, by calculating intensity, percentage and combined scores. Protein expression levels of STAT3 (total, tyrosine and serine phosphorylated), p38 and cyclin D1 were assessed in two OSCC cell lines. p38 inhibition was achieved by pharmacological agent(SB2023580). Cell proliferation and viability rates were also evaluated. Phospho-p38 immunoexpression was intense in almost all tumor specimens, nevertheless did not correlate with tumor differentiation. Inhibition of p38 with SB203580 did not appear to affect tyrosine or serine phosphorylated STAT3 as well as cyclin D1 levels in both cell lines. Moreover, p38 inhibition resulted in mild dose-dependent decreases in cell growth and viability in both cell lines. p38 is highly expressed in OSCC but does not seem to mediate the oncogenic STAT3 pathway. However, changes found in proliferation and viability may suggest that p38 functions as potent regulator of HNSCC. Understanding the complexity of p38 signaling and cross-talk between other major molecules, may guide the development of novel pharmacologic therapies for cancer treatment and prevention.

Zoledronate Impairs Socket Healing after Extraction of Teeth with Experimental Periodontitis.

Osteonecrosis of the jaws (ONJ) is a rare but severe complication of antiresorptive medications, such as bisphosphonates, used in the treatment of bone malignancy or osteoporosis. Tooth extraction and dental disease have been strongly associated with ONJ development. Here, we investigated molecular and cellular markers of socket healing after extraction of healthy or teeth with experimental periodontitis (EP) in Wistar-Han rats treated with zoledronic acid (ZA). We included 4 experimental groups: vehicle-treated animals with extraction of healthy teeth or teeth with ligature-induced EP and ZA-treated animals with extraction of healthy teeth or teeth with EP. Animals were pretreated with vehicle or ZA for a week, and EP was induced. Four weeks later, the second maxillary molars were extracted; sockets were allowed to heal for 4 wk; animals were euthanized; and maxillae were isolated. Radiographically, extraction sockets in groups 1, 2, and 3 demonstrated normal healing. Contrary incomplete socket healing was noted after extraction of teeth with EP in ZA-treated rats of group 4. Histologically, persistent inflammation and extensive osteonecrosis were seen in group 4. Disorganization of the collagen network, collagen type III predominance, and lack of collagen fiber insertion in the necrotic bone were associated with impaired socket healing. Cells positive for MMP-9, MMP-13, and α-SMA expression were present at the areas of epithelial invagination and adjacent to osteonecrotic bone. Importantly, human biopsies from patients with ONJ showed similar findings. Our data emphasize the importance of dental disease and tooth extraction in ONJ pathogenesis and help delineate an altered profile in wound-healing markers during ONJ development.

ERK1/2, JNK and STAT3 activation and correlation with tumor differentiation in oral SCC.

Signal transducer and activator of transcription 3 (STAT3) and mitogen activated protein kinases (MAPKs), including ERK and JNK, have been implicated in oral squamous cell carcinoma (OSCC) development and progression. Our purpose was to evaluate the levels of activated STAT3, ERK1/2 and JNK by immunohistochemistry in OSCC and to investigate possible correlations of these molecules with each other as well as with the degree of tumor differentiation. Immunohistochemical assessment of the phosphorylated levels of STAT3(tyrosine/ serine), ERK1/2 and JNK was performed in 60 OSCC, including well, moderately and poorly differentiated tumors. Semiquantitative scoring system was used, by calculating intensity of immunostaining, percentage of positive cells and combined scores. Statistics included Fisher's test, Student's T-Test and Kruskal-Wallis analysis, Spearman's correlation coefficient and multivariate logistic regression analyses. Immunohistochemical levels of both pSTAT3(tyr) and pERK1/2 showed statistically significant differences between well and poorly differentiated tumors with the latter receiving higher mean percentage, intensity and total scores. On the other hand, pJNK showed statistically significantly higher intensity levels in moderately compared to poorly differentiated tumors. pSTAT3(ser) immunoexpression did not appear to correlate with tumor differentiation. Between different molecules, more pronounced, pERK1/2 levels exhibited statistically significant positive correlation with pSTAT3(ser), pSTAT3(tyr) and pJNK expression. ERK1/2 and STAT3 activation (as assessed by tyrosine but not serine phosphorylation) could contribute to a less differentiated phenotype in OSCC, while JNK activation may have an opposite, although possibly less pronounced, effect. Positive correlations between MAPK and STAT3 levels may indicate a direct crosstalk and/or regulation by common upstream pathways.