Javier A. Mas-Rosario

Curcumin has antioxidant properties resulting from its radical scavenging ability and inhibition of inflammation‐associated factors. However, its lack of solubility, instability, and poor bioavailability are impediments to its therapeutic use. As potential alternatives, we synthesized and performed chemical analysis of thirty diarylidene‐N‐methyl‐4‐piperidone (DANMP), diheteroarylidene‐N‐methyl‐4‐piperidone (DHANMP), and spirobibenzopyran (SBP) derivatives, one of which was also characterized by single crystal X‐ray diffraction. All compounds were evaluated for antioxidant activity via 2,2‐Diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging assay and for drug‐like properties in silico. A subset of five compounds was investigated in terms of aqueous solubilities, which were significantly improved compared to that of curcumin. In vitro assessments of cellular and anti‐inflammatory effects were conducted via real time polymerase chain reaction (RT‐PCR) and Griess assays to evaluate the presence of inflammatory/activated (M1) markers and production of nitric oxide (NO) species, which are associated with inflammation. The five compounds reduced levels of markers and NO to extents similar to or better than curcumin in inflamed cells, and showed no adverse effects on cell viability. We show that these compounds possess anti‐inflammatory properties and may be used as curcumin‐substitutes with improved characteristics.

Uncontrolled inflammation is responsible for acute and chronic diseases in the lung. Regulating expression of pro-inflammatory genes in pulmonary tissue using small interfering RNA (siRNA) is a promising approach to combatting respiratory diseases. However, siRNA therapeutics are generally hindered at the cellular level by endosomal entrapment of delivered cargo and at the organismal level by inefficient localization in pulmonary tissue. Here we report efficient anti-inflammatory activity in vitro and in vivo using polyplexes of siRNA and an engineered cationic polymer (PONI-Guan). PONI-Guan/siRNA polyplexes efficiently deliver siRNA cargo to the cytosol for highly efficient gene knockdown. Significantly, these polyplexes exhibit inherent targeting to inflamed lung tissue following intravenous administration in vivo. This strategy achieved effective (>70%) knockdown of gene expression in vitro and efficient (>80%) silencing of TNF-α expression in lipopolysaccharide (LPS)-challenged mice using a low (0.28 mg/kg) siRNA dosage.

There is a significant need for new small molecule anti-inflammatory compounds. Curcumin, a small molecule natural product from the Turmeric (Curcuma longa) plant, has well-known anti-oxidant properties, resulting from its radical scavenging ability and inhibition of inflammation-associated factors. However, its lack of solubility, instability, and poor bioavailability and biodistribution characteristics are an impediment to its use. To circumvent these issues while retaining curcumin’s biological activity, we synthesized twenty-one diarylidene-N-methyl-4-piperidones (DANMPs), four diheteroarylidene-N-methyl-4-piperidones (DHANMPs), and five spirobibenzopyran (SBP) derivatives. All were screened in terms of anti-oxidant activity via a cell-free 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and for drug-like properties in silico. In the former, some compounds possessed improved radical scavenging behavior versus ascorbic acid, which was used as a benchmark. Conformity to simulated Lipinski’s parameters and Absorption, Distribution, Metabolism, and Excretion (ADME) studies indicated the DANMPs, DHANMPs, and SBPs to be potentially useful compounds. A subset of molecules was investigated in terms of their aqueous solubilities, which were significantly improved compared to that of curcumin. In vitro assessments of the cellular and anti-inflammatory effects of these compounds were conducted using RAW264.7 macrophages. RT-PCR and Griess assays were used to evaluate the presence of inflammatory/activated (M1) markers and production of nitric oxide (NO) species, which are associated with inflammation, respectively. While the compounds did not affect non-stimulated (naïve) macrophages, they did reduce levels of markers and NO to extents similar to or better than curcumin in inflamed cells. Our results indicate that these pharmacophores possess anti-inflammatory properties and can be used as curcumin-substitutes with improved characteristics. Further investigation into their mechanisms of action and potential use in the treatment of inflammatory diseases is merited.

Macrophages are white blood cells that play disparate roles in homeostasis and immune responses. They can reprogram their phenotypes to pro-inflammatory (M1) or anti-inflammatory (M2) states in response to their environment. About 8–15% of the macrophage transcriptome has circadian oscillations, including genes closely related to their functioning. As circadian rhythms are associated with cellular phenotypes, we hypothesized that polarization of macrophages to opposing subtypes might differently affect their circadian rhythms. We tracked circadian rhythms in RAW 264.7 macrophages using luminescent reporters. Cells were stably transfected with Bmal1:luc and Per2:luc reporters, representing positive and negative components of the molecular clock. Strength of rhythmicity, periods and amplitudes of time series were assessed using multiple approaches. M1 polarization decreased amplitudes and rhythmicities of Bmal1:luc and Per2:luc, but did not significantly affect periods, while M2 polarization increased periods but caused no substantial alterations to amplitudes or rhythmicity. As macrophage phenotypes are also altered in the presence of cancer cells, we tested circadian effects of conditioned media from mouse breast cancer cells. Media from highly aggressive 4T1 cells caused loss of rhythmicity, while media from less aggressive EMT6 cells yielded no changes. As macrophages play roles in tumors, and oncogenic features are associated with circadian rhythms, we tested whether conditioned media from macrophages could alter circadian rhythms of cancer cells. Conditioned media from RAW 264.7 cells resulted in lower rhythmicities and periods, but higher amplitudes in human osteosarcoma, U2OS-Per2:luc cells. We show that phenotypic changes in macrophages result in altered circadian characteristics and suggest that there is an association between circadian rhythms and macrophage polarization state. Additionally, our data demonstrate that macrophages treated with breast cancer-conditioned media have circadian phenotypes similar to those of the M1 subtype, and cancer cells treated with macrophage-conditioned media have circadian alterations, providing insight to another level of cross-talk between macrophages and cancer.

Immunotherapy has become a promising new approach for cancer treatment due to the immune system’s ability to remove tumors in a safe and specific manner. Many tumors express anti-inflammatory factors that deactivate the local immune response or recruit peripheral macrophages into pro-tumor roles. Because of this, effective and specific ways of activating macrophages into anti-tumor phenotypes is highly desirable for immunotherapy purposes. Here, the use of a small molecule TLR agonist as a macrophage activator for anti-cancer therapy is reported. This compound, referred to as PBI1, demonstrated unique activation characteristics and expression patterns compared to treatment with LPS, through activation of TLR4. Furthermore, PBI1 treatment resulted in anti-tumor immune behavior, enhancing macrophage phagocytic efficiency five-fold versus non-treated macrophages. Additive effects were observed via use of a complementary strategy (anti-CD47 antibody), resulting in ∼10-fold enhancement of phagocytosis, suggesting this small molecule approach could be used in conjunction with other therapeutics.