TGF-ß-induced fibrosis: A review on the underlying mechanism and potential therapeutic strategies.

Transforming growth factor-beta (TGF-ß) plays multiple homeostatic roles in the regulation of inflammation, proliferation, differentiation and would healing of various tissues. Many studies have demonstrated that TGF-ß stimulates activation and proliferation of fibroblasts, which result in extracellular matrix deposition. Its increased expression can result in many fibrotic diseases, and the level of expression is often correlated with disease severity. On this basis, inhibition of TGF-ß and its activity has great therapeutic potential for the treatment of various fibrotic diseases such as pulmonary fibrosis, renal fibrosis, systemic sclerosis and etc. By understanding the molecular mechanism of TGF-ß signaling and activity, researchers were able to develop different strategies in order to modulate the activity of TGF-ß. Antisense oligonucleotide was developed to target the mRNA of TGF-ß to inhibit its expression. There are also neutralizing monoclonal antibodies that can target the TGF-ß ligands or αvß6 integrin to prevent binding to receptor or activation of latent TGF-ß respectively. Soluble TGF-ß receptors act as ligand traps that competitively bind to the TGF-ß ligands. Many small molecule inhibitors have been developed to inhibit the TGF-ß receptor at its cytoplasmic domain and also intracellular signaling molecules. Peptide aptamer technology has been used to target downstream TGF-ß signaling. Here, we summarize the underlying mechanism of TGF-ß-induced fibrosis and also review various strategies of inhibiting TGF-ß in both preclinical and clinical studies.

A Synthetic Curcuminoid Analogue, 2,6-Bis-4-(Hydroxyl-3-Methoxybenzylidine)-Cyclohexanone (BHMC) Ameliorates Acute Airway Inflammation of Allergic Asthma in Ovalbumin-Sensitized Mice.

2,6-Bis-(4-hydroxyl-3-methoxybenzylidine) cyclohexanone (BHMC), a synthetic curcuminoid analogue, has been shown to exhibit anti-inflammatory properties in cellular models of inflammation and improve the survival of mice from lethal sepsis. We further evaluated the therapeutic effect of BHMC on acute airway inflammation in a mouse model of allergic asthma. Mice were sensitized and challenged with ovalbumin (OVA), followed by intraperitoneal administration of 0.1, 1, and 10 mg/kg of BHMC. Bronchoalveolar lavage fluid, blood, and lung samples were collected, and the respiratory function was measured. OVA sensitization and challenge increased airway hyperresponsiveness (AHR) and pulmonary inflammation. All three doses of BHMC (0.1-10 mg/kg) significantly reduced the number of eosinophils, lymphocytes, macrophages, and neutrophils, as well as the levels of Th2 cytokines (IL-4, IL-5 and IL-13) in bronchoalveolar lavage fluid (BALF) as compared to OVA-challenged mice. However, serum level of IgE was not affected. All three doses of BHMC (0.1-10 mg/kg) were effective in suppressing the infiltration of inflammatory cells at the peribronchial and perivascular regions, with the greatest effect observed at 1 mg/kg which was comparable to dexamethasone. Goblet cell hyperplasia was inhibited by 1 and 10 mg/kg of BHMC, while the lowest dose (0.1 mg/kg) had no significant inhibitory effect. These findings demonstrate that BHMC, a synthetic nonsteroidal small molecule, ameliorates acute airway inflammation associated with allergic asthma, primarily by suppressing the release of inflammatory mediators and goblet cell hyperplasia to a lesser extent in acute airway inflammation of allergic asthma.

Advax delta inulin adjuvant overcomes immune immaturity in neonatal mice thereby allowing single-dose influenza vaccine protection.

Neonates are at high risk for influenza morbidity and mortality due to immune immaturity and lack of priming by prior influenza virus exposure. Inactivated influenza vaccines are ineffective in infants under six months and to provide protection in older children generally require two doses given a month apart. This leaves few options for rapid protection of infants, e.g. during an influenza pandemic. We investigated whether Advax™, a novel polysaccharide adjuvant based on delta inulin microparticles could help overcome neonatal immune hypo-responsiveness. We first tested whether it was possible to use Advax to obtain single-dose vaccine protection of neonatal pups against lethal influenza infection. Inactivated influenza A/H1N1 vaccine (iH1N1) combined with Advax™ adjuvant administered as a single subcutaneous immunization to 7-day-old mouse pups significantly enhanced serum influenza-specific IgM, IgG1, IgG2a and IgG2b levels and was associated with a 3-4 fold increase in the frequency of splenic influenza-specific IgM and IgG antibody secreting cells. Pups immunized with Advax had significantly higher splenocyte influenza-stimulated IFN-γ, IL-2, IL-4, and IL-10 production by CBA and a 3-10 fold higher frequency of IFN-γ, IL-2, IL-4 or IL-17 secreting T cells by ELISPOT. Immunization with iH1N1+Advax induced robust protection of pups against virus challenge 3 weeks later, whereas pups immunized with iH1N1 antigen alone had no protection. Protection by Advax-adjuvanted iH1N1 was dependent on memory B cells rather than memory T cells, with no protection in neonatal µMT mice that are B-cell deficient. Hence, Advax adjuvant overcame neonatal immune hypo-responsiveness and enabled single-dose protection of pups against otherwise lethal influenza infection, thereby supporting ongoing development of Advax™ as a neonatal vaccine adjuvant.

Severe acute respiratory syndrome-associated coronavirus vaccines formulated with delta inulin adjuvants provide enhanced protection while ameliorating lung eosinophilic immunopathology.

UNLABELLED: Although the severe acute respiratory syndrome-associated coronavirus (SARS-CoV) epidemic was controlled by nonvaccine measures, coronaviruses remain a major threat to human health. The design of optimal coronavirus vaccines therefore remains a priority. Such vaccines present major challenges: coronavirus immunity often wanes rapidly, individuals needing to be protected include the elderly, and vaccines may exacerbate rather than prevent coronavirus lung immunopathology. To address these issues, we compared in a murine model a range of recombinant spike protein or inactivated whole-virus vaccine candidates alone or adjuvanted with either alum, CpG, or Advax, a new delta inulin-based polysaccharide adjuvant. While all vaccines protected against lethal infection, addition of adjuvant significantly increased serum neutralizing-antibody titers and reduced lung virus titers on day 3 postchallenge. Whereas unadjuvanted or alum-formulated vaccines were associated with significantly increased lung eosinophilic immunopathology on day 6 postchallenge, this was not seen in mice immunized with vaccines formulated with delta inulin adjuvant. Protection against eosinophilic immunopathology by vaccines containing delta inulin adjuvants correlated better with enhanced T-cell gamma interferon (IFN-γ) recall responses rather than reduced interleukin-4 (IL-4) responses, suggesting that immunopathology predominantly reflects an inadequate vaccine-induced Th1 response. This study highlights the critical importance for development of effective and safe coronavirus vaccines of selection of adjuvants based on the ability to induce durable IFN-γ responses. IMPORTANCE: Coronaviruses such as SARS-CoV and Middle East respiratory syndrome-associated coronavirus (MERS-CoV) cause high case fatality rates and remain major human public health threats, creating a need for effective vaccines. While coronavirus antigens that induce protective neutralizing antibodies have been identified, coronavirus vaccines present a unique problem in that immunized individuals when infected by virus can develop lung eosinophilic pathology, a problem that is further exacerbated by the formulation of SARS-CoV vaccines with alum adjuvants. This study shows that formulation of SARS-CoV spike protein or inactivated whole-virus vaccines with novel delta inulin-based polysaccharide adjuvants enhances neutralizing-antibody titers and protection against clinical disease but at the same time also protects against development of lung eosinophilic immunopathology. It also shows that immunity achieved with delta inulin adjuvants is long-lived, thereby overcoming the natural tendency for rapidly waning coronavirus immunity. Thus, delta inulin adjuvants may offer a unique ability to develop safer and more effective coronavirus vaccines.