Multiple myeloma (MM) is a fatal malignancy ranking second in prevalence among hematological tumors. Continuous efforts are being made to develop innovative and more effective treatments. The preclinical evaluation of new therapies relies on the use of murine models of the disease.

Galectin-3 is a human lectin involved in many cellular processes including differentiation, apoptosis, angiogenesis, neoplastic transformation, and metastasis. We evaluated galectin-3C, an N-terminally truncated form of galectin-3 that is thought to act as a dominant negative inhibitor, as a potential treatment for multiple myeloma (MM). Galectin-3 was expressed at varying levels by all 9 human MM cell lines tested. In vitro galectin-3C exhibited modest anti-proliferative effects on MM cells and inhibited chemotaxis and invasion of U266 MM cells induced by stromal cell-derived factor (SDF)-1α. Galectin-3C facilitated the anticancer activity of bortezomib, a proteasome inhibitor approved by the FDA for MM treatment. Galectin-3C and bortezomib also synergistically inhibited MM-induced angiogenesis activity in vitro. Delivery of galectin-3C intravenously via an osmotic pump in a subcutaneous U266 cell NOD/SCID mouse model of MM significantly inhibited tumor growth. The average tumor volume of bortezomib-treated animals was 19.6% and of galectin-3C treated animals was 13.5% of the average volume of the untreated controls at day 35. The maximal effect was obtained with the combination of galectin-3C with bortezomib that afforded a reduction of 94% in the mean tumor volume compared to the untreated controls at day 35. In conclusion, this is the first study to show that inhibition of galectin-3 is efficacious in a murine model of human MM. Our results demonstrated that galectin-3C alone was efficacious in a xenograft mouse model of human MM, and that it enhanced the anti-tumor activity of bortezomib in vitro and in vivo. These data provide the rationale for continued testing of galectin-3C towards initiation of clinical trials for treatment of MM.

Neisseria gonorrhoeae is an exclusively human pathogen that commonly infects the urogenital tract resulting in gonorrhoea. Empirical treatment of gonorrhoea with antibiotics has led to multidrug resistance and the need for new therapeutics. Inactivation of lipooligosaccharide phosphoethanolamine transferase A (EptA), which attaches phosphoethanolamine to lipid A, results in attenuation of the pathogen in infection models. Small molecules that inhibit EptA are predicted to enhance natural clearance of gonococci via the human innate immune response.

Gonorrhea, caused by the bacterium Neisseria gonorrhoeae (Gc), is characterized by neutrophil influx to infection sites. Gc has developed mechanisms to resist killing by neutrophils that include modifications to its surface lipooligosaccharide (LOS). One such LOS modification is sialylation: Gc sialylates its terminal LOS sugars with cytidine-5'-monophosphate-N-acetylneuraminic acid (CMP-NANA) scavenged from the host using LOS sialyltransferase (Lst), since Gc cannot make its own sialic acid. Sialylation enables sensitive strains of Gc to resist complement-mediated killing in a serum-dependent manner. However, little is known about the contribution of sialylation to complement-independent, direct Gc-neutrophil interactions. In the absence of complement, we found sialylated Gc expressing opacity-associated (Opa) proteins decreased the oxidative burst and granule exocytosis from primary human neutrophils. In addition, sialylated Opa+ Gc survived better than vehicle treated or Δlst Gc when challenged with neutrophils. However, Gc sialylation did not significantly affect Opa-dependent association with or internalization of Gc by neutrophils. Previous studies have implicated sialic acid-binding immunoglobulin-type lectins (Siglecs) in modulating neutrophil interactions with sialylated Gc. Blocking neutrophil Siglecs with antibodies that bind to their extracellular domains eliminated the ability of sialylated Opa+ Gc to suppress oxidative burst and resist neutrophil killing. These findings highlight a new role for sialylation in Gc evasion of human innate immunity, with implications for the development of vaccines and therapeutics for gonorrhea.

PFOS induces Sertoli cell injury using testicular cells isolated from rodent testes, but it remains unknown if PFOS has similar effects in humans. Herein, we maintained human Sertoli cells in a mitotically active state in vitro, thus enabling transfection experiments that altered gene expression to explore the molecular mechanism(s) underlying toxicant-induced cell injury. Human Sertoli cells obtained from men at ages 15, 23, 36 and 40 were cultured in vitro. These differentiated Sertoli cells remained mitotically active when cultured in the presence of 10% FBS (fetal bovine serum), with a replication time of ~1-3 weeks. At ~80% confluency, they were used for studies including toxicant exposure, immunoblotting, immunofluorescence analysis, tight junction (TJ)-permeability assessment, and overexpression of BTB (blood-testis barrier) regulatory genes such as FAK and its phosphomimetic mutants. PFOS was found to induce Sertoli cell injury through disruptive effects on actin microfilaments and microtubule (MT) organization across the cell cytosol. As a consequence, these cytoskeletal networks failed to support cell adhesion at the BTB. Overexpression of a FAK phosphomimetic and constitutively active mutant p-FAK-Y407E in these cells was capable of rescuing the PFOS-induced injury through corrective cellular organization of cytoskeletal elements.

Acute myocardial infarction (MI) causes inflammation, collagen deposition, and reparative fibrosis in response to myocyte death and, subsequently, a pathological myocardial remodelling process characterized by excessive interstitial fibrosis, driving heart failure (HF). Nonetheless, how or when to limit excessive fibrosis for therapeutic purposes remains uncertain. Galectin-3, a major mediator of organ fibrosis, promotes cardiac fibrosis and remodelling. We performed a preclinical assessment of a protein inhibitor of galectin-3 (its C-terminal domain, Gal-3C) to limit excessive fibrosis resulting from MI and prevent ventricular enlargement and HF.