Natural immunoglobulin M initiates an inflammatory response important for both hepatic ischemia reperfusion injury and regeneration in mice.

Complement plays a role in both hepatic ischemia reperfusion (IR) injury (IRI) and liver regeneration, but it is not clear how complement is activated in either process. We investigated the role of self-reactive immunoglobulin M (IgM) antibodies in activating complement after hepatic IR and liver resection. Natural IgM antibodies that recognize danger-associated molecular patterns (neoepitopes) activate complement following both hepatic IR and liver resection. Antibody-deficient Rag1-/- mice were protected from hepatic IRI, but had increased hepatic injury and an impaired regenerative response after 70% partial hepatectomy (PHx). We identified two IgM monoclonal antibodies (mAbs) that specifically reversed the effect of Rag1 deficiency in both models; B4 (recognizes Annexin IV) and C2 (recognizes subset of phospholipids). Focusing on the B4-specific response, we demonstrated sinusoidal colocalization of IgM and C3d in Rag1-/- mice that were reconstituted with B4 mAb, and furthermore that the Annexin IV neoepitope is specifically and similarly expressed after both hepatic IR and PHx in wild-type (WT) mice. A single-chain antibody construct (scFv) derived from B4 mAb blocked IgM binding and reduced injury post-IR in WT mice, although, interestingly, B4scFv did not alter regeneration post-PHx, indicating that anti-Annexin IV antibodies are sufficient, but not necessary, for the regenerative response in the context of an entire natural antibody repertoire. We also demonstrated expression of the B4 neoepitope in postischemic human liver samples obtained posttransplantation and a corollary depletion in IgM recognizing the B4 and C2 neoepitopes in patient sera following liver transplantation. Conclusion: These data indicate an important role for IgM in hepatic IRI and regeneration, with a similar cross-species injury-specific recognition system that has implications for the design of neoepitope targeted therapeutics. (Hepatology 2018;67:721-735).

Disseminated blastomycosis in coalworkers' pneumoconiosis.

Blastomyces dermatitidis is a thermally dimorphic fungus that can cause pulmonary, extrapulmonary, or disseminated infections. Though it can infect both immune-competent and immunocompromised hosts, the disease can be severe in immunocompromised hosts. Exposure to silica dust is associated with silicosis, and this is associated with impaired immunity and an increased risk of mycobacterial and fungal infections. The fungal infections commonly associated with pneumoconiosis are pulmonary aspergillosis, histoplasmosis, coccidioidomycosis, and cryptococcosis. However, there is a dearth of data on the association of pneumoconiosis and blastomycosis. Clinical deterioration and new cavitary lesions in patients with pneumoconiosis should alert clinicians of new pulmonary infection. Traditional sputum sampling may lead to poor diagnostic yield, because the organism is frequently surrounded by a fibrotic wall. Aggressive diagnostic testing with lung or skin biopsies may be warranted. We present the first reported case of disseminated blastomycosis in a patient with coalworkers' pneumoconiosis.

Heat shock protein-mediated protection against Cisplatin-induced hair cell death.

Cisplatin is a highly successful and widely used chemotherapy for the treatment of various solid malignancies in both adult and pediatric patients. Side effects of cisplatin treatment include nephrotoxicity and ototoxicity. Cisplatin ototoxicity results from damage to and death of cells in the inner ear, including sensory hair cells. We showed previously that heat shock inhibits cisplatin-induced hair cell death in whole-organ cultures of utricles from adult mice. Since heat shock protein 70 (HSP70) is the most upregulated HSP in response to heat shock, we investigated the role of HSP70 as a potential protectant against cisplatin-induced hair cell death. Our data using utricles from HSP70 (-/-) mice indicate that HSP70 is necessary for the protective effect of heat shock against cisplatin-induced hair cell death. In addition, constitutive expression of inducible HSP70 offered modest protection against cisplatin-induced hair cell death. We also examined a second heat-inducible protein, heme oxygenase-1 (HO-1, also called HSP32). HO-1 is an enzyme responsible for the catabolism of free heme. We previously showed that induction of HO-1 using cobalt protoporphyrin IX (CoPPIX) inhibits aminoglycoside-induced hair cell death. Here, we show that HO-1 also offers significant protection against cisplatin-induced hair cell death. HO-1 induction occurred primarily in resident macrophages, with no detectable expression in hair cells or supporting cells. Depletion of macrophages from utricles abolished the protective effect of HO-1 induction. Together, our data indicate that HSP induction protects against cisplatin-induced hair cell death, and they suggest that resident macrophages mediate the protective effect of HO-1 induction.

Dissecting the complement pathway in hepatic injury and regeneration with a novel protective strategy.

Liver resection is commonly performed under ischemic conditions, resulting in two types of insult to the remnant liver: ischemia reperfusion injury (IRI) and loss of liver mass. Complement inhibition is recognized as a potential therapeutic modality for IRI, but early complement activation products are also essential for liver regeneration. We describe a novel site-targeted murine complement inhibitor, CR2-CD59, which specifically inhibits the terminal membrane attack complex (MAC), and we use this protein to investigate the complement-dependent balance between liver injury and regeneration in a clinical setting of pharmacological inhibition. CR2-CD59 did not impact in vivo generation of C3 and C5 activation products but was as effective as the C3 activation inhibitor CR2-Crry at ameliorating hepatic IRI, indicating that the MAC is the principle mediator of hepatic IRI. Furthermore, unlike C3 or C5 inhibition, CR2-CD59 was not only protective but significantly enhanced hepatocyte proliferation after partial hepatectomy, including when combined with ischemia and reperfusion. Remarkably, CR2-CD59 also enhanced regeneration after 90% hepatectomy and improved long-term survival from 0 to 70%. CR2-CD59 functioned by increasing hepatic TNF and IL-6 levels with associated STAT3 and Akt activation, and by preventing mitochondrial depolarization and allowing recovery of ATP stores.