The present invention relates to compounds, compositions, and methods for the study, diagnosis, and treatment of traits, diseases and conditions that respond to the modulation of cyclic nucleotide type 4 phosphodiesterase (PDE4B) gene expression and/or activity, including PDE4B1, PDE4B2, and PDE4B3 gene expression and/or activity. The present invention is also directed to compounds, compositions, and methods relating to traits, diseases and conditions that respond to the modulation of expression and/or activity of genes involved in cyclic nucleotide type 4 phosphodiesterase (PDE4B) gene expression pathways or other cellular processes that mediate the maintenance or development of such traits, diseases and conditions, including but not limited to IL-6, IL-7, IL-8, IL-15, TNF-alpha and matrix metalloproteinases (MMPs), such as MMP-I, MMP-2, MMP-3, MMP-9 and MMP-12. Specifically, the invention relates to double stranded nucleic acid molecules including small nucleic acid molecules, such as short interfering nucleic acid (siNA), short interfering RNA (siRNA), double-stranded RNA (dsRNA), micro-RNA (miRNA), and short hairpin RNA (shRNA), and multifunctional siNA molecules capable of mediating RNA interference (RNAi) against cyclic nucleotide type 4 phosphodiesterase (PDE4B) gene expression, including cocktails of such small nucleic acid molecules and lipid nanoparticle (LNP) formulations of such small nucleic acid molecules. The present invention also relates to small nucleic acid molecules, such as siNA, siRNA, antisense and others that can inhibit the function of endogenous RNA molecules or RNAi pathway components (RNAi inhibitors), such as endogenous micro-RNA (miRNA) (e.g, miRNA inhibitors) or endogenous short interfering RNA (siRNA), (e.g., siRNA inhibitors) or that can inhibit the function of RISC (e.g., RISC inhibitors), to modulate PDE4B gene expression by interfering with the regulatory function of such endogenous RNAs or proteins associated with such endogenous RNAs (e.g., RISC) including cocktails of such small nucleic acid molecules and lipid nanoparticle (LNP) formulations of such small nucleic acid molecules. Such small nucleic acid molecules are useful, for example, in providing compositions to prevent, inhibit, or reduce inflammatory, respiratory, and autoimmune diseases, traits, and conditions, and/or other disease states associated with PDE4B gene expression or activity in a subject or organism.